Search

The authors present opinions based on their applied experiences of working with female athletes in combination with the existing evidence-based literature. Most of the existing menstrual cycle research focuses on a few steady-state time points within the pre-defined menstrual cycle phases, yet this disregards the day-to-day hormonal changes that women have to accommodate to perform optimally and consistently. The traditional research models are inadequate for studying symptoms and symptom management, and ultimately for supporting athletes to perform well throughout the entirety of their cycle. As such, the monitoring of the day-to-day variation, particularly during the transitions between menstrual cycle phases appears to be an important "overlooked" consideration. This is particularly pertinent considering the known intra-individual and inter-individual variation in menstrual cycle characteristics. Anecdotal and research evidence supports the idea that athletes can use non-pharmacological solutions to mitigate negative menstrual cycle symptoms and do not need to "grit their teeth and roll with it". However, further research (including case studies) is needed in this important research area. Such knowledge should be and needs to be widespread amongst practitioners and athletes as they should not have to figure this out alone. As such, researchers and practitioners need to put more work into understanding symptom aetiology, symptom clusters and their relationship with hormonal changes, menstrual cycle phases and transitions, with potential for a profound impact on individual athlete health and well-being. In so doing, those working with female athletes need to continue building on the recent progress made in educating athletes and practitioners; for example, normalising the discussion of and about the menstrual cycle and all of its implications. [ABSTRACT FROM AUTHOR]

In the current aging society, the occurrence of the locomotive syndrome, a condition in which the locomotive organs are impaired, is increasing. The locomotive system includes support (bones), mobility and impact absorption (joints and intervertebral disks), drive and control (muscles, nerves), and network (blood vessels). The impairment of any of those systems can lead to a major decrease in quality of life. In recent years, several studies on methods to improve and prevent conditions impairing the locomotive syndrome have been conducted. Almost in parallel with the structure supporting mobility and body functions, testosterone levels decrease with age. Testosterone is a hormone-regulating several pathways affecting each aspect of the locomotive syndrome. Testosterone is regulated by the pituitary gland triggering several processes in the body through genomic and non-genomic pathways, affecting muscles, bones, nerves, joints, intervertebral discs, and blood vessels. The purpose of this review is to investigate the role of testosterone in each of the systems involved in the locomotive syndrome. [ABSTRACT FROM AUTHOR]

Background: Both strength and endurance training are included in global exercise recommendations and are the main components of training programs for competitive sports. While an abundance of research has been published regarding concurrent strength and endurance training, only a small portion of this research has been conducted in females or has addressed their unique physiological circumstances (e.g., hormonal profiles related to menstrual cycle phase, menstrual dysfunction, and hormonal contraceptive use), which may influence training responses and adaptations. Objective: The aim was to complete a systematic review of the scientific literature regarding training adaptations following concurrent strength and endurance training in apparently healthy adult females. Methods: A systematic electronic search for articles was performed in July 2021 and again in December 2022 using PubMed and Medline. This review followed, where applicable, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of the included studies was assessed using a modified Downs and Black checklist. Inclusion criteria were (1) fully published peer-reviewed publications; (2) study published in English; (3) participants were healthy normal weight or overweight females of reproductive age (mean age between > 18 and < 50) or presented as a group (n > 5) in studies including both females and males and where female results were reported separately; (4) participants were randomly assigned to intervention groups, when warranted, and the study included measures of maximal strength and endurance performance; and (5) the duration of the intervention was ≥ 8 weeks to ensure a meaningful training duration. Results: Fourteen studies met the inclusion criteria (seven combined strength training with running, four with cycling, and three with rowing or cross-country skiing). These studies indicated that concurrent strength and endurance training generally increases parameters associated with strength and endurance performance in female participants, while several other health benefits such as, e.g., improved body composition and blood lipid profile were reported in individual studies. The presence of an "interference effect" in females could not be assessed from the included studies as this was not the focus of any included research and single-mode training groups were not always included alongside concurrent training groups. Importantly, the influence of concurrent training on fast-force production was limited, while the unique circumstances affecting females were not considered/reported in most studies. Overall study quality was low to moderate. Conclusion: Concurrent strength and endurance training appears to be beneficial in increasing strength and endurance capacity in females; however, multiple research paradigms must be explored to better understand the influence of concurrent training modalities in females. Future research should explore the influence of concurrent strength and endurance training on fast-force production, the possible presence of an "interference effect" in athletic populations, and the influence of unique circumstances, such as hormone profile, on training responses and adaptations. [ABSTRACT FROM AUTHOR]

The adaptogen Rhodiola rosea (RR) may mitigate stress responses and have beneficial effects on endurance capacity (EC) and mental performance. Heat acclimation (HA) improves EC in the heat, but the potential impact of RR on the HA process is unknown. Therefore, our intent was to determine if RR has a positive impact on HA. Twenty male subjects (age, 22.5 ± 3.0 years) completed 2 EC tests involving walking (6 km·h−1) until volitional exhaustion in a climate chamber (air temperature, 42 °C; relative humidity, 18%) before (H1) and after (H2) an 8-day HA period. One group (SHR; n = 10) ingested standardised extract SHR-5 of RR (a single daily dose of 432 mg), while a second group (PLC; n = 10) administered a placebo prior to each HA session. Efficacy of HA was evaluated on the basis of changes that occurred from H1 to H2 in the time to exhaustion (TTE), exercise heart rate (HR), core and skin temperatures ( Tc, Tsk), stress hormones, ratings of perceived exertion (RPE) and fatigue (RPF), and thermal sensation (TS). HA significantly increased TTE (133.1 ± 44.1 min in H1; 233.4 ± 59.8 min in H2; p < 0.0001) and decreased ( p < 0.0001) HR, Tc, Tsk, stress hormones as well as RPE, RPF, and TS. However, the magnitude of all these changes was similar ( p > 0.05) in the SHR and PLC groups. These results suggest that the use of RR during HA has no beneficial performance, physiological, or perceptual effects in young healthy males. [ABSTRACT FROM AUTHOR]

High levels of gamma glutamyltransferase (gamma-GT) and alanine aminotransferase (ALT), as well as fatty liver index (FLI) has been associated with higher cardiovascular disease risk factors in adults. The aim of this study was to examine the relationship between gamma-GT, ALT, and fatty liver index FLI levels across a gradient number of ideal cardiovascular health metrics in a representative sample of adults from the Chilean National Health Survey 2009–2010. Data from 1,023 men and 1,449 women (≥ 15 years) from the Chilean Health Survey 2009–2010 were analyzed. Ideal cardiovascular health was defined as meeting ideal levels of the following components: four behaviours (smoking, body mass index, physical activity and diet adherence) and three factors (total cholesterol, blood pressure and fasting glucose). Adults were grouped into three categories according to their number of ideal cardiovascular health metrics: ideal (5–7 metrics), intermediate (3–4 metrics), and poor (0–2 metrics). Blood levels of gamma-GT and ALT were measured and the FLI was calculated. A higher number of ideal cardiovascular health index metric was associated with lower gamma-GT, ALT and FLI (p from trend analysis <0.001). Also, adults meeting at least 3–4 metrics were predicted less likely to have prevalence of abnormal levels of gamma-GT and FLI (p<0.001) compared to adults who met only 0–2 metrics. These findings reinforce the usefulness of the ideal cardiovascular health metrics proposed by the American Heart Association as a tool to identify target subjects and promote cardiovascular health in South-American adults. [ABSTRACT FROM AUTHOR]

Objective • The primary aim of this study was to compare the effects of 12 weeks of 3 resistance training methods (traditional, circular and interval) compared with no exercise on the plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in nonathletic men with obesity. Materials and Methods • The study sample included 44 nonathletic men with obesity who were randomly assigned to one of four groups: traditional, circular, and interval resistance training or a control group. IL-6 and TNF-α cytokines were analyzed using commercial ELISA kits. Results • The results of mixed-design ANOVA with repeated measures showed that there was significant correspondence between the type of training used and time on TNF-α (F(1,40) = 2212.35; P = .001; estimates (ES) = 0.98) and IL-6 (F(1,40) = 2423.69; P = .001; ES = 0.98) levels. Results indicated that there was a significant difference between the resistance training groups and the control group in both TNF-α (F(3, 40) = 11.39; P = .001; ES = 0.46) and IL-6 (F(3, 40) = 4.65; P = .007; ES = 0.25) levels. Conclusion • All types of resistance training decreased biomarker outcomes compared with the control group. However, interval resistance training showed a significant difference from circular resistance training in IL-6 level, while there was no significant difference between the effects of the 3 types of resistance training on TNF-α levels. [ABSTRACT FROM AUTHOR]

Purpose: This article aimed to study the associations between aspects of endurance exercise training and sexual libido in healthy men using a cross-sectional online survey study design. Methods: A developed online survey questionnaire was used. The questionnaire was based on preexisting validated questionnaires and was used to assess elements of physical characteristics, exercise training habits, and libido of participants (n = 1077). Three evidence-based categories were created for the primary outcome of total libido score and low, normal, and high-response category sets. The high and normal categories were combined to form a high/normal score group, and the low category formed a low score group. Odds ratio (OR) values were calculated to examine group categorization. Results: Age, training intensity, and training duration of participants had significant (P < 0.02) univariate relationships, with libido scores, and were thus included in the multivariate model. In the multivariate model, training intensity (P < 0.0001) and duration (P < 0.002) components were the most significantly associated with libido group designation (high/normal vs low). Participants with the lowest (OR = 6.9, 95% confidence interval [CI] = 2.6-17.9) and mid-range training intensities (OR = 2.8, 95% CI = 1.4-5.3) had greater odds of high/normal libido state than those with the highest training intensity. Participants with the shorter (OR = 4.1, 95% CI = 1.6-10.0) and mid-range training durations (OR = 2.5, 95% CI = 1.3-4.8) at their current intensity also had greater odds of high/normal libido score than those with a greatest duration. Conclusion: Exposure to higher levels of chronic intense and greater durations of endurance training on a regular basis is significantly associated with a decreased libido scores in men. Clinicians who treat male patients for sexual disorders and/or council couples on infertility issues should consider the degree ofendurance exercise training a man is performing as a potential complicating factor. [ABSTRACT FROM AUTHOR]

Introduction: That the vastus medialis oblique (VMO) is a functional unit of the vastus medialis (VM) is disputed. Delayed VMO activation predicts patellofemoral pain, which has higher rates in women.Methods: Single MUs and surface electromyogram (EMG) were collected from the VMO and VM of 9 men and 9 women. Men were tested once; women were tested during 5 menstrual phases. Coherence was assessed for motor unit (MU) firings within and between the VM and VMO using multilevel logistic models to determine statistical significance.Results: Compared with women, men have 741% (MU pairs) and 256% (MU-EMG pairs) greater odds of common drive (0-5 Hz) coherent oscillations. MU pairs from the VMO and the dual VM/VMO complex have 228% and 212% greater odds of coherent oscillations in the beta band (15-35 Hz) compared with VM pairs.Conclusions: The VM and VMO are neurologically different muscles; control of the VM complex is sexually dimorphic. [ABSTRACT FROM AUTHOR]

Research should equitably reflect responses in men and women. Including women in research, however, necessitates an understanding of the ovarian hormones and menstrual phase variations in both cellular and systems physiology. This review outlines recent advances in the multiplicity of ovarian hormone molecular signaling that elucidates the mechanisms for menstrual phase variability in exercise metabolism. The prominent endogenous estrogen, 17-β-estradiol (E2), molecular structure is bioactive in stabilizing plasma membranes and quenching free radicals and both E2 and progesterone (P4) promote the expression of antioxidant enzymes attenuating exercise-induced muscle damage in the late follicular (LF) and mid-luteal (ML) phases. E2 and P4 bind nuclear hormone receptors and membrane-bound receptors to regulate gene expression directly or indirectly, which importantly includes cross-regulated expression of their own receptors. Activation of membrane-bound receptors also regulates kinases causing rapid cellular responses. Careful analysis of these signaling pathways explains menstrual phase-specific differences. Namely, E2-promoted plasma glucose uptake during exercise, via GLUT4 expression and kinases, is nullified by E2-dominant suppression of gluconeogenic gene expression in LF and ML phases, ameliorated by carbohydrate ingestion. E2 signaling maximizes fat oxidation capacity in LF and ML phases, pending low-moderate exercise intensities, restricted nutrient availability, and high E2:P4 ratios. P4 increases protein catabolism during the luteal phase by indeterminate mechanisms. Satellite cell function supported by E2-targeted gene expression is countered by P4, explaining greater muscle strengthening from follicular phase-based training. In totality, this integrative review provides causative effects, supported by meta-analyses for quantitative actuality, highlighting research opportunities and evidence-based relevance for female athletes. [ABSTRACT FROM AUTHOR]

Cachexia in cancer patients is a condition marked by severe tissue wasting and a myriad of quality of life and health consequences. Cachexia is also directly linked to the issues of morbidity and survivability in cancer patients. Therapeutic means of mitigating cachexia and its effects are thus critical in cancer patient treatment. We present a discussion on the use of physical exercise activities in the context of such treatment as a means to disruption the tissue wasting effects (i.e., muscle tissue losses via anorexigenic pro-inflammatory cytokines) of cachexia. In addition we propose a theoretical model (Exercise Anti-Cachectic Hypothetical—"EACH" model) as to how exercise training may promote a disruption in the cycle of events leading to advancing cachexia and in turn promote an enhanced functionality and thus improved quality of life in cancer patients. [ABSTRACT FROM AUTHOR]

Objective: To provide background information on methodologic factors that influence and add variance to endocrine outcome measurements. Our intent is to aid and improve the quality of exercise science and sports medicine research endeavors of investigators inexperienced in endocrinology. Background: Numerous methodologic factors influence human endocrine (hormonal) measurements and, consequently, can dramatically compromise the accuracy and validity of exercise and sports medicine research. These factors can be categorized into those that are biologic and those that are procedural-analytic in nature. Recommendations: Researchers should design their studies to monitor, control, and adjust for the biologic and procedural-analytic factors discussed within this paper. By doing so, they will find less variance in their hormonal outcomes and thereby will increase the validity of their physiologic data. These actions can assist the researcher in the interpretation and understanding of endocrine data and, in turn, make their research more scientifically sound. [ABSTRACT FROM AUTHOR]

Our findings indicate that the participants of an 18 week intensive endurance exercise training program experienced significant (p < 0.001) reductions in resting testosterone (-25 to -45% decrease from pre-training), with some reaching the clinical criteria for androgen deficiency during the training regimen. Nonetheless, none of the participants displayed any running performance decrement, in fact, the opposite occurred (+18.6% improvement; p < 0.05). These preliminary findings suggest acute decreases in testosterone in and of itself may not be entirely indicative of a compromised exercise performance potential although elements of reproductive and bone health may still be compromised. [ABSTRACT FROM AUTHOR]

Physiological and psychological systems work together to determine energy intake and output, and thus maintain adipose tissue. In addition, adipose tissue secretes leptin and cytokines, which induces satiety and has been linked to catecholamines, cortisol, insulin, human growth hormone, thyroid hormones, gonadotropin and lipolysis. Thus, adipose tissue is acted upon by a number of physiological stimuli, including hormones, and simultaneously, is an active component in the regulation of its own lipid content. All of the hormones mentioned above are associated with each other and respond to exercise and exercise training. Thus, exercise is one of the major links between the hormonal modulators of energy intake and output. It appears that the sympathetic nervous system and the catecholamines are key components facilitating the lipolytic activity during exercise. These two neuroendocrine factors directly affect adipose metabolism and metabolic hormones that influence adipose metabolism. Acute low- and moderate-intensity exercise causes hormonal changes that facilitate lipolytic activity. Exercise training reduces these hormonal responses, but the sensitivity to these hormones increases so that lipolysis may be facilitated. Large amounts of adipose tissue blunt the metabolic hormonal responses to exercise, but the sensitivity of these hormones is increased; thus maintaining normal lipolytic activity. Although the physiological role of the endocrine system during exercise and training is significant, other training effects may have as great, or greater influence on lipolytic activity in adipose tissue. [ABSTRACT FROM AUTHOR]

This pilot study assessed the feasibility and combined effect of aerobic exercise (AE) and mindfulness meditation (MM), compared with MM alone and a control (CON) condition, on stress, anxiety, and depression in high-stress college-based young adults. Thirty-two participants (84.4% F, 20.5 ± 2.7 years, 23.9 ± 5.0 kg/m2) were randomized to a four-week, AE + MM (n = 16), MM (n = 10), or control intervention (n = 6). ANOVA revealed non-significant, but noteworthy group x time interactions (perceived stress: p = 0.09; anxiety/depression: p = 0.07). Both AE + MM and MM seem to be feasible strategies to reduce levels of stress, anxiety and depression in college-based young adults. [ABSTRACT FROM AUTHOR]

Increased levels of physical activity are associated with many positive health outcomes in men including reproductive health as recently reported by Vieira et al. [[1]] in I The Aging Male i . Based upon the work of Vieira et al. [[1]], we wondered whether these exercise-related reductions in testosterone reached the clinical diagnostic threshold for androgen deficiency (AD) and occurred across the life span of runners. Nonetheless, outcomes point to the possible existence of greater occurrences of AD in men habitually engaged in endurance-based exercise training over a longer period of time (i.e., hence also typically older). [Extracted from the article]

Background: Knowledge of the long-term effects of soccer training on hematological, hormonal, inflammatory, and muscle damage markers and physical performance may help to better design strength and conditioning programs for performance development and injury prevention for the individual player and the team. Objectives: The aim of this systematic review was to summarize and discuss evidence on the long-term effects of soccer training on selected hematological, hormonal, inflammatory, and muscle damage markers and physical performance in elite and professional soccer players. A second goal was to investigate associations between selected physiological markers and measures of performance. Methods: Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, a systematic literature search was conducted in four electronic databases (PubMed, ISI Web of Knowledge, Web of Science, and SPORTDiscus) from inception until August 2020 to identify articles related to soccer training effects. To be included in this systematic review, studies had to examine male elite (national level) and/or professional (international level) soccer players aged > 17 years and a soccer training period > 4 weeks, and report outcomes related to hematological, hormonal, inflammatory, muscle damage, and performance markers. Results: The search syntax initially identified 2420 records. After screening titles, abstracts, and full texts, 20 eligible studies were included in this systematic review, with training durations lasting between 4 and 18 weeks in 15 studies, around 6 months in four studies, and around 1 year in one study. Effects of long-term soccer training revealed parameter-specific increases or decreases in hematological, hormonal, inflammatory, and muscle damage markers and physical performance. Two studies showed a moderate increase in hematological markers such as hemoglobin (effect size [ES] = 0.67–0.93). Parameter-specific changes were noted for hormonal markers in the form of increases for total testosterone (ES = 0.20–0.67) and free testosterone (FT) (ES = 0.20–0.65) and decreases for cortisol (ES = − 0.28 to − 1.31). Finally, moderate to very large increases were found for muscle damage markers such as creatine kinase (ES = 0.94–6.80) and physical performance such as countermovement jump (CMJ) height (ES = 0.50–1.11) and squat jump (SJ) height (ES = 0.65–1.28). After long-term periods of soccer training, significant positive correlations were found between percentage change (Δ%) in FT and Δ% in CMJ height (r = 0.94; p = 0.04) and between Δ% in total testosterone/cortisol (TT/C) ratio and Δ% in SJ (r = 0.89; p = 0.03). Conclusions: Findings suggest that long-term soccer training induces increases/decreases in hematological, hormonal, inflammatory, and muscle damage markers and physical performance in male elite and professional soccer players. These fluctuations can be explained by different contextual factors (e.g., training load, duration of training, psychological factors, mood state). Interestingly, the observed changes in hormonal parameters (FT and TT/C) were related to vertical jump performance changes (e.g., CMJ and SJ). Anabolic hormones and TT/C can possibly be used as a tool to identify physical performance alteration after long-term soccer training. [ABSTRACT FROM AUTHOR]

Purpose: Less physical activity has been associated with systemic biomarkers of cartilage breakdown after anterior cruciate ligament reconstruction (ACLR). However, previous research lacks analysis of deleterious cartilage compositional changes and objective physical activity after ACLR. The purpose of this study was to determine the association between physical activity quantified via accelerometer-based measures of daily steps and time in moderate-to-vigorous physical activity (MVPA), and T1rho magnetic resonance imaging (MRI) of the femoral articular cartilage, a marker of proteoglycan density in individuals with ACLR. Methods: Daily steps and MVPA were assessed over 7 d using an accelerometer worn on the hip in 26 individuals between 6 and 12 months after primary unilateral ACLR. Resting T1rho MRI was collected bilaterally, and T1rho MRI interlimb ratios (ILR: ACLR limb/contralateral limb) were calculated for lateral and medial femoral condyle regions of interest. We conducted univariate linear regression analyses to determine associations between T1rho MRI ILRs and daily steps and MVPA with and without controlling for sex. Results: Greater T1rho MRI ILR of the central lateral femoral condyle, indicative of less proteoglycan density in the ACLR limb, was associated with greater time in MVPA (R 2 = 0.178, P = 0.032). Sex-adjusted models showed significant interaction terms between daily steps and sex in the anterior (P = 0.025), central (P = 0.002), and posterior (P = 0.002) medial femoral condyle. Conclusions: Lesser physical activity may be a risk factor for maintaining cartilage health after ACLR; additionally, the relationship between physical activity and cartilage health may be different between males and females. [ABSTRACT FROM AUTHOR]

Beta-alanine, caffeine, and nitrate are dietary supplements generally recognized by the sport and exercise science community as evidence-based ergogenic performance aids. Evidence supporting the efficacy of these supplements, however, is greatly skewed due to research being conducted primarily in men. The physiological differences between men and women, most notably in sex hormones and menstrual cycle fluctuations, make generalizing male data to the female athlete inappropriate, and potentially harmful to women. This narrative review outlines the studies conducted in women regarding the efficacy of beta-alanine, caffeine, and nitrate supplementation for performance enhancement. Only nine studies on beta-alanine, 15 on caffeine, and 10 on nitrate in healthy women under the age of 40 years conducted in normoxia conditions were identified as relevant to this research question. Evidence suggests that beta-alanine may lower the rate of perceived exertion and extend training bouts in women, leading to greater functional adaptations. Studies of caffeine in women suggest the physiological responder status and caffeine habituation may contribute to caffeine's efficacy, with a potential plateau in the dose–response relationship of performance enhancement. Nitrate appears to vary in influence based on activity type and primary muscle group examined. However, the results summarized in the limited literature for each of these three supplements provide no consensus on dosage, timing, or efficacy for women. Furthermore, the literature lacks considerations for hormonal status and its role in metabolism. This gap in sex-based knowledge necessitates further research on these ergogenic supplements in women with greater considerations for the effects of hormonal status. [ABSTRACT FROM AUTHOR]

Myllyaho, MM, Ihalainen, JK, Hackney, AC, Valtonen, M, Nummela, A, Vaara, E, Häkkinen, K, Kyröläinen, H, and Taipale, RS. Hormonal contraceptive use does not affect strength, endurance, or body composition adaptations to combined strength and endurance training in women. J Strength Cond Res 35(2): 449-457, 2021-This study examined the effects of a 10-week period of high-intensity combined strength and endurance training on strength, endurance, body composition, and serum hormone concentrations in physically active women using hormonal contraceptives (HCs, n = 9) compared with those who had never used hormonal contraceptives (NHCs, n = 9). Training consisted of 2 strength training sessions and 2 high-intensity running interval sessions per week. Maximal bilateral isometric leg press (Isom), maximal bilateral dynamic leg press (one repetition maximum [1RM]), countermovement jump (CMJ), a 3,000-m running test (3,000 m), body composition, and serum hormone levels were measured before and after training between days 1-5 of each subject's menstrual cycle. Both groups increased 1RM and CMJ: HC = 13.2% (p < 0.001) and 9.6% (p < 0.05), and NHC = 8.3% (p < 0.01) and 8.5% (p < 0.001). Hormonal contraceptive improved 3,000 m by 3.5% (p < 0.05) and NHC by 1% (n.s.). Never used hormonal contraceptive increased lean mass by 2.1% (p < 0.001), whereas body fat percentage decreased from 23.9 ± 6.7 to 22.4 ± 6.0 (-6.0%, p < 0.05). No significant changes were observed in body composition in HC. No significant between-group differences were observed in any of the performance variables. Luteinizing hormone concentrations decreased significantly (p < 0.05) over 10 weeks in NHC, whereas other hormone levels remained statistically unaltered in both groups. It seems that the present training is equally appropriate for improving strength, endurance, and body composition in women using HC as those not using HC without disrupting hypothalamic-pituitary-gonadal axis function. [ABSTRACT FROM AUTHOR]

Low energy availability (LEA) occurs inadvertently and purposefully in many athletes across numerous sports; and well planned, supervised periods with moderate LEA can improve body composition and power to weight ratio possibly enhancing performance in some sports. LEA however has the potential to have negative effects on a multitude of physiological and psychological systems in female and male athletes. Systems such as the endocrine, cardiovascular, metabolism, reproductive, immune, mental perception, and motivation as well as behaviors can all be impacted by severe (serious and/or prolonged or chronic) LEA. Such widely diverse effects can influence the health status, training adaptation, and performance outcomes of athletes leading to both direct changes (e.g., decreased strength and endurance) as well as indirect changes (e.g., reduced training response, increased risk of injury) in performance. To date, performance implications have not been well examined relative to LEA. Therefore, the intent of this narrative review is to characterize the effects of short‐, medium‐, and long‐term exposure to LEA on direct and indirect sports performance outcomes. In doing so we have focused both on laboratory settings as well as descriptive athletic case‐study‐type experiential evidence. [ABSTRACT FROM AUTHOR]

Context: Gait biomechanics are linked to biochemical changes that contribute to the development of posttraumatic knee osteoarthritis in individuals with anterior cruciate ligament reconstruction (ACLR). It remains unknown if modifying peak loading during gait using real-time biofeedback will result in acute biochemical changes related to cartilage metabolism. Objective: To determine if acutely manipulating peak vertical ground reaction force (vGRF) during gait influences acute changes in serum cartilage oligomeric matrix protein concentration (sCOMP) among individuals with ACLR. Design: Crossover study. Patients or Other Participants: Thirty individuals with unilateral ACLR participated (70% female, age = 20.43 ± 2.91 years old, body mass index = 24.42 ± 4.25, months post-ACLR = 47.83 ± 26.97). Additionally, we identified a subgroup of participants who demonstrated an increase in sCOMP after the control or natural loading condition (sCOMPCHANGE > 0 ng/mL, n = 22, 70% female, age = 20.32 ± 3.00 years old, body mass index = 24.73 ± 4.33, months post-ACLR = 47.27 ± 29.32). Main Outcome Measure(s): Serum was collected both prior to and immediately after each condition to determine SCOMPCHANGE. Intervention(s): All participants attended 4 sessions that involved 20 minutes of walking on a force-measuring treadmill consisting of a control condition (natural loading) followed by random ordering of 3 loading conditions with real-time biofeedback: (1) symmetric vGRF between limbs, (2) a 5% increase in vGRF (high loading) and (3) a 5% decrease in vGRF (low loading). A general linear mixed model was used to determine differences in sCOMPchange between altered loading conditions and the control group in the entire cohort and the subgroup. Results: The sCOMPCHANGE was not different across loading conditions for the entire cohort (F3.29 = 1.34, P = .282). Within the subgroup, sCOMPCHANGE was less during high loading (1.95 ± 24.22 ng/mL, t21 = -3.53, P = .005) and symmetric loading (9.93 ± 21.45 ng/mL, t21 =-2.86, P= .025) compared with the control condition (25.79 ± 21.40 ng/mL). Conclusions: Increasing peak vGRF during gait decreased sCOMP in individuals with ACLR who naturally demonstrated an increase in sCOMP after 20 minutes of walking. [ABSTRACT FROM AUTHOR]

Context: Military service members commonly sustain lower extremity stress fractures (SFx). How SFx risk factors influence bone metabolism is unknown. Understanding how SFx risk factors influence bone metabolism may help to optimize risk-mitigation strategies. Objective: To determine how SFx risk factors influence bone metabolism. Design: Cross-sectional study. Setting: Military service academy. Patients or other participants: Forty-five men (agepre = 18.56 ± 1.39 years, heightpre = 176.95 ± 7.29 cm, masspre = 77.20 ± 9.40 kg; body mass indexpre = 24.68 ± 2.87) who completed Cadet Basic Training (CBT). Individuals with neurologic or metabolic disorders were excluded. Intervention(s): We assessed SFx risk factors (independent variables) with (1) the Landing Error Scoring System (LESS), (2) self-reported injury and physical activity questionnaires, and (3) physical fitness tests. We assessed bone biomarkers (dependent variables; procollagen type I amino-terminal propeptide [PINP] and cross-linked collagen telopeptide [CTx-1]) via serum. Main outcome measure(s): A markerless motion-capture system was used to analyze trunk and lower extremity biomechanics via the LESS. Serum samples were collected post-CBT; enzyme-linked immunosorbent assays determined PINP and CTx-1 concentrations, and PINP : CTx-1 ratios were calculated. Linear regression models demonstrated associations between SFx risk factors and PINP and CTx-1 concentrations and PINP : CTx-1 ratio. Biomarker concentration mean differences with 95% confidence intervals were calculated. Significance was set a priori using α ≤ .10 for simple and α ≤ .05 for multiple regression analyses. Results: The multiple regression models incorporating LESS and SFx risk factor data predicted the PINP concentration (R2 = 0.47, P = .02) and PINP : CTx-1 ratio (R2 = 0.66, P = .01). The PINP concentration was increased by foot internal rotation, trunk flexion, CBT injury, sit-up score, and pre- to post-CBT mass changes. The CTx-1 concentration was increased by heel-to-toe landing and post-CBT mass. The PINP : CTx-1 ratio was increased by foot internal rotation, lower extremity sagittal-plane displacement (inversely), CBT injury, sit-up score, and pre- to post-CBT mass changes. Conclusions: Stress fracture risk factors accounted for 66% of the PINP : CTx-1 ratio variability, a potential surrogate for bone health. Our findings provide insight into how SFx risk factors influence bone health. This information can help guide SFx risk-mitigation strategies. [ABSTRACT FROM AUTHOR]

Background: Well programmed strength and conditioning training is an indispensable part of the long-term training process for athletes in individual and team sports to improve performance and prevent injuries. Yet, there is a limited number of studies available that examine the effects of resistance training (RT) on muscular fitness and physiological adaptations in elite female athletes. Objectives: This systematic review aimed to summarize recent evidence on the long-term effects of RT or combinations of RT with other strength-dominated exercise types on muscular fitness, muscle morphology, and body composition in female elite athletes. Materials and Methods: A systematic literature search was conducted in nine electronic databases (Academic Search Elite, CINAHL, ERIC, Open Access Theses and Dissertations, Open Dissertations, PsycINFO, PubMed/MEDLINE, Scopus, and SPORTDiscus) from inception until March 2022. Key search terms from the MeSH database such as RT and strength training were included and combined using the operators "AND," "OR," and "NOT". The search syntax initially identified 181 records. After screening for titles, abstracts, and full texts, 33 studies remained that examined the long-term effects of RT or combinations of RT with other strength-dominated exercise types on muscular fitness, muscle morphology, and body composition in female elite athletes. Results: Twenty-four studies used single-mode RT or plyometric training and nine studies investigated the effects of combined training programs such as resistance with plyometric or agility training, resistance and speed training, and resistance and power training. The training duration lasted at least 4 weeks, but most studies used ~ 12 weeks. Studies were generally classified as 'high-quality' with a mean PEDro score of 6.8 (median 7). Irrespective of the type or combination of RT with other strength-dominated exercise regimens (type of exercise, exercise duration, or intensity), 24 out of 33 studies reported increases in muscle power (e.g., maximal and mean power; effect size [ES]: 0.23 < Cohen's d < 1.83, small to large), strength (e.g., one-repetition-maximum [1RM]; ES: 0.15 < d < 6.80, small to very large), speed (e.g., sprint times; ES: 0.01 < d < 1.26, small to large), and jump performance (e.g., countermovement/squat jump; ES: 0.02 < d < 1.04, small to large). The nine studies that examined the effects of combined training showed significant increases on maximal strength (ES: 0.08 < d < 2.41, small to very large), muscle power (ES: 0.08 < d < 2.41, small to very large), jump and sprint performance (ES: 0.08 < d < 2.41, small to very large). Four out of six studies observed no changes in body mass or percentage of body fat after resistance or plyometric training or combined training (ES: 0.026 < d < 0.492, small to medium). Five out of six studies observed significant changes in muscle morphology (e.g., muscle thickness, muscle fiber cross-sectional area; ES: 0.23 < d < 3.21, small to very large). However, one study did not find any changes in muscle morphology (i.e., muscle thickness, pennation angle; ES: 0.1 < d < 0.19, small). Conclusion: Findings from this systematic review suggest that RT or combined RT with other strength-dominated exercise types leads to significant increases in measures of muscle power, strength, speed, and jump performance in elite female athletes. However, the optimal dosage of programming parameters such as training intensity and duration necessary to induce large effects in measures of muscular fitness and their physiological adaptations remain to be resolved in female elite athletes. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the psychophysiological responses during self-selected exercise intensity over the course of the menstrual cycle (MC). Methods: Seventeen healthy women with regular MCs completed three randomized treadmill bouts of 30 min of self-selected exercise intensity during menstruation, mid-follicular, and late luteal phases. Anxiety, menstrual distress (i.e., pain, behavior change, autonomic reaction, fluid retention, and negative affect) and profile of mood (i.e., tension, depression, and anger) were measured before exercise. Arousal, heart rate (HR), motivation, rating of perceived exertion and affective valence were measured before, during and after each exercise session. Results: Anger, anxiety, behavior change, pain, and negative affect were significantly greater (p <.05) during menstruation compared to the mid-follicular phase, whereas fluid retention, anger, behavior change, and autonomic reaction were greater (p <.05) during the late luteal phase compared with the mid-follicular phase. Participants felt more negative affective valence and less motivation to start exercise during menstruation compared with other MC phases. Average treadmill speed (5.8 ± 1.1 vs 6.0 ± 0.7 vs 5.9 ± 0.7 km/h–1, p =.36) and %HRmax (74.9 ± 3.2 vs 77.8 ± 5.4 vs 77.4 ± 7.1%, p =.40) did not differ between menstruation, mid-follicular, and late luteal phases. Also, noteworthy is that participants self-selected an intensity that exceeded the minimum levels recommended for health and cardiorespiratory fitness promotion (64–70% HRmax). Conclusions: Results of this study indicate that psychophysiological responses are negatively impacted mainly during menstruation and the late luteal phase of the MC. These findings may be helpful for professionals who work to promote the initiation and maintenance of exercise in women. [ABSTRACT FROM AUTHOR]

Abstract Background Aberrant mechanical loading during gait is hypothesized to contribute to the development of posttraumatic osteoarthritis following anterior cruciate ligament reconstruction. Our purpose was to determine if peak vertical ground reaction force and instantaneous vertical ground reaction force loading rate associate with the acute change in serum cartilage oligomeric matrix protein following a 20-minute bout of walking. Methods We enrolled thirty individuals with a unilateral anterior cruciate ligament reconstruction. Peak vertical ground reaction force and instantaneous vertical ground reaction force loading rate were extracted from the first 50% of the stance phase of gait during a 60-second trial. Blood samples were collected immediately before and after 20 min of treadmill walking at self-selected speed. The change in serum cartilage oligomeric matrix protein from pre- to post-walking was calculated. Stepwise linear regression models were used to determine the association between each outcome of loading and the change in serum cartilage oligomeric matrix protein after accounting for sex, gait speed, time since anterior cruciate ligament reconstruction, graft type, and history of concomitant meniscal procedure (ΔR2). Findings Lesser peak vertical ground reaction force (ΔR2 = 0.208; β = −0.561; P = 0.019) and instantaneous vertical ground reaction force loading rate (ΔR2 = 0.168; β = −0.519; P = 0.037) on the anterior cruciate ligament reconstructed limb associated with a greater increase in serum cartilage oligomeric matrix protein following 20 min of walking. Interpretation Mechanical loading may be a future therapeutic target for altering the acute biochemical response to walking in individuals with an anterior cruciate ligament reconstruction. Highlights • Lesser magnitude of loading associated with a greater biochemical response after walking. • Lesser instantaneous rate of loading was associated with a greater biochemical response. • Limb symmetry of loading characteristics was not associated with the biochemical response. [ABSTRACT FROM AUTHOR]

This study aimed to determine how different resistance training protocols affect gremlin 1, macrophage migration inhibitory factor (MIF), cardiometabolic, and anthropometric measures in obese men. Forty-four males with obesity (weight: 93.2 ± 2.2 kg, BMI: 32.9 ± 1.2 kg/m2, age: 27.5 ± 9.4 years) were randomly assigned to traditional resistance training (TRT, n = 11), circuit resistance training (CRT, n = 11), interval resistance training (IRT, n = 11) or control (C, n = 11) groups. TRT group performed ten exercises at 50% of 1RM with 14 repetitions for three sets and 30 seconds rest interval between exercises and 1.5 min rest between sets, the CRT protocol included three circuits of 10 exercises, at an intensity of 50% of 1-RM, 14 repetitions with a minimum rest (< 15 s) between exercises and 3 min rest between sets, and the IRT group performed two sets of the same exercises with 50% of 1 RM, and 14 repetitions were followed with active rest of 25% of 1RM and 14 repetitions. All resistance training groups performed 60 min per session resistance exercises, 3 days per week, for 12 weeks. Measurements were taken at baseline and after 12 weeks of exercise training. Resistance training (TRT, CRT, and IRT) significantly decreased plasma levels of gremlin (TRT from 231.0 ± 5.8 to 210.0 ± 11.6 ng/ml, CRT from 226.0 ± 7.6 to 188.0 ± 7.7 ng/ml and, IRT from 227.0 ± 6.3 to 183.0 ± 9.0 ng/ml, effect size (ES): 0.50), MIF (TRT from 251.0 ± 7.4 to 260.0 ± 6.5 ng/ml, CRT from 248.0 ± 10.9 to 214.0 ± 9.0 ng/ml and, IRT from 247.0 ± 8.9 to 196.0 ± 6.9 ng/ml, ES: 0.55) and CRP (TRT from 28.4 ± 1.7 to 23.3 ± 2.1 nmol/l, CRT from 28.5 ± 2.2 to 21.1 ± 1.8 nmol/l, IRT from 28.1 ± 1.3 to 20.8 ± 1.3 nmol/l, ES: 0.49) compared to the control group (p <.05), but these reduction were greater in the CRT and IRT groups compared to the TRT group (p <.05). The CRT and IRT protocols had more beneficial improvement in gremlin 1, MIF, body composition, and cardiometabolic risk factors compared to the beneficial changes produced by TRT protocol. [ABSTRACT FROM AUTHOR]

The aim of this systematic review was to summarize the evidence on the acute and long-term effects of exercise training on PV, in both trained and untrained individuals and to examine associations between changes in %PVV and change in physical/physiological performance. Despite the status of participants and the exercise duration or intensity, all the acute studies reported a significant decrease of PV (effect size: 0.85

Individuals who undergo anterior cruciate ligament reconstruction (ACLR) are at higher risk of posttraumatic osteoarthritis. Altered joint tissue loading caused by aberrant gait biomechanics leads to deleterious changes in joint health linked to the onset of posttraumatic osteoarthritis. Knee braces have been used to modify joint tissue loading in individuals with joint injury, yet the effects of walking with a brace after ACLR on biomechanical, biochemical, and structural cartilage outcomes are unknown. To compare biomechanical, biochemical, and structural outcomes between braced and nonbraced walking in individuals with ACLR. Crossover study. Research laboratory. A total of 34 individuals with unilateral ACLR (18 females, 16 males; time since ACLR = 50.1 ± 36.8 months). Gait biomechanics were assessed during braced and unbraced conditions on separate days. Vertical ground reaction force, knee-flexion angle, and internal knee-extension moment waveforms were evaluated throughout the stance phase and compared between conditions. Percentage changes in serum cartilage oligomeric matrix protein (%ΔCOMP) and femoral cartilage cross-sectional area (%ΔCSA) measured via ultrasound were calculated after a 3000-step walking protocol. Braced walking increased the knee-flexion angle (largest difference = 3.56°; Cohen d effect size = 1.72) and knee-extension moment (largest difference = −0.48% body weight × height; Cohen d effect size = −1.14) compared with nonbraced walking but did not influence vertical ground reaction force. Whereas no difference (P =.20) in %ΔCOMP existed between the braced and nonbraced conditions in the entire cohort (n = 30 with complete blood data), a larger increase (P =.04) in %ΔCOMP was seen during nonbraced than braced walking in individuals who demonstrated increased COMP during nonbraced walking. No difference (P =.86) in %ΔCSA was present between the braced and nonbraced conditions. Braced walking may improve sagittal-plane gait biomechanics and %ΔCOMP in a subset of individuals who demonstrate a typical increased COMP response to load (ie, increase in COMP) after nonbraced walking. [ABSTRACT FROM AUTHOR]

The effects of acute consumption of L-Arginine (L-Arg) in healthy young individuals are not clearly defined, and no studies on the effects of L-Arg in individuals with abnormal body mass index undertaking strenuous exercise exist. Thus, we examined whether supplementation with L-Arg diminishes cardiopulmonary exercise testing responses, such as ventilation (VE), VE/VCO2, oxygen uptake (VO2), and heart rate, in response to an acute session of high-intensity interval exercise (HIIE) in overweight men. A double-blind, randomized crossover design was used to study 30 overweight men (age, 26.5 ± 2.2 years; body weight, 88.2 ± 5.3 kilogram; body mass index, 28.0 ± 1.4 kg/m2). Participants first completed a ramped-treadmill exercise protocol to determine VO2max velocity (vVO2max), after which they participated in two sessions of HIIE. Participants were randomly assigned to receive either 6 g of L-Arg or placebo supplements. The HIIE treadmill running protocol consisted of 12 trials, including exercise at 100% of vVO2max for 1 min interspersed with recovery intervals of 40% of vVO2max for 2 min. Measurements of VO2 (ml·kg−1·min−1), VE (L/min), heart rate (beat per min), and VE/VCO2 were obtained. Supplementation with L-Arg significantly decreased all cardiorespiratory responses during HIIE (placebo+HIIE vs. L-Arg+HIIE for each measurement: VE [80.9 ± 4.3 L/min vs. 74.6 ± 3.5 L/min, p <.05, ES = 1.61], VE/VCO2 [26.4 ± 1.3 vs. 24.4 ± 1.0, p <.05, ES = 1.8], VO2 [26.4 ± 0.8 ml·kg−1·min−1 vs. 24.4 ± 0.9 ml·kg−1·min−1, p <.05, ES = 2.2], and heart rate [159.7 ± 6.3 beats/min vs. 155.0 ± 3.7 beats/min, p <.05, d = 0.89]). The authors conclude consuming L-Arg before HIIE can alleviate the excessive physiological strain resulting from HIIE and help to increase exercise tolerance in participants with a higher body mass index who may need to exercise on a regular basis for extended periods to improve their health. [ABSTRACT FROM AUTHOR]

Introduction: An in-depth understanding of the healthy cartilage response to activities of daily living is needed to better understand the complex relationship between cartilage health and loading. The purpose was to assess the role of loading on the acute serum cartilage oligomeric matrix protein (COMP) response in recreationally active individuals. Methods: Forty individuals without previous lower extremity injury participated in this repeated-measures study in which each participant completed all conditions during independent data collection sessions separated by at least 1 wk. An antecubital blood draw was performed before and after walking, drop-landing, and control (i.e., sitting) conditions. Commercially available enzyme-linked immunosorbent assays measured COMP concentration. The acute COMP response was quantified as the percent change of COMP concentration from before to after each condition. A one-way, repeated-measures ANOVA compared the acute COMP response between conditions. Post hoc Pearson product–moment correlation and chi-square analysis determined the relationship between the walking and drop-landing acute COMP response within individuals. Results: Acute COMP response was greater after walking (+4.2, P = 0.008) and drop landing (+4.6%, P = 0.002) compared with control (−2.3%), but did not differ between the walking and drop-landing conditions (P = 0.596). The magnitudes of the acute COMP response during walking and drop landing were correlated (r = 0.56, P < 0.001). However, the direction (i.e., either increase or decrease) of COMP was not the same after the walking and drop-landing conditions (χ1 = 0.870, P = 0.351). Conclusions: Walking and drop landing produced a greater acute COMP response when compared with a control condition in healthy individuals, but the acute COMP response was similar between the two physical activity conditions, although the conditions differed in magnitude and frequency of loading. [ABSTRACT FROM AUTHOR]

We compared the acute response and recovery of ultrasonography (US) cartilage outcomes (i.e., thickness, cross-sectional area, and echo intensity) between walking, drop-landing and control conditions in 43 young adults with no history of lower extremity injury. A femoral cartilage US assessment was performed before and after each condition to determine the acute cartilage response and recovery at 15, 30 and 45 min. Percentage change scores from pre- to all post-time points were used for analysis. Acute cartilage response and recovery were analyzed with a 3 × 4 (condition × time) repeated-measures analysis of variance. Greater deformation of the medial and lateral femoral cartilage was observed immediately after both the walking and drop-landing conditions compared with the control condition. Cartilage deformation after the drop-landing condition required longer time to recover compared with the walking condition. The femoral cartilage deformation was not accompanied by concurrent alterations in cartilage echo intensity. [ABSTRACT FROM AUTHOR]

This is the first report of the psychobiology of stress in BASE jumpers, one of the most dangerous forms of extreme sport. We tested the hypotheses that indicators of emotional style (temperament) predict salivary cortisol reactivity, whereas indicators of intentional goal-setting (persistence and character) predict salivary alpha-amylase reactivity during BASE jumping. Ninety-eight subjects completed the Temperament and Character Inventory (TCI) the day before the jump, and 77 also gave salivary samples at baseline, pre-jump on the bridge over the New River Gorge, and post-jump upon landing. Overall BASE jumpers are highly resilient individuals who are highly self-directed, persistent, and risk-taking, but they are heterogeneous in their motives and stress reactivity in the Hypothalamic-Pituitary-Adrenal (HPA) stress system (cortisol reactivity) and the sympathetic arousal system (alpha-amylase reactivity). Three classes of jumpers were identified using latent class analysis based on their personality profiles, prior jumping experience, and levels of cortisol and alpha-amylase at all three time points. “Masterful” jumpers (class 1) had a strong sense of self-directedness and mastery, extensive prior experience, and had little alpha-amylase reactivity and average cortisol reactivity. “Trustful” jumpers (class 2) were highly cooperative and trustful individuals who had little cortisol reactivity coincident with the social support they experienced prior to jumping. “Courageous” jumpers (class 3) were determined despite anxiety and inexperience, and they had high sympathetic reactivity but average cortisol activation. We conclude that trusting social attachment (Reward Dependence) and not jumping experience predicted low cortisol reactivity, whereas persistence (determination) and not jumping experience predicted high alpha-amylase reactivity. [ABSTRACT FROM AUTHOR]

Aberrant joint loading contributes to the development of posttraumatic knee osteoarthritis (PTOA) following anterior cruciate ligament reconstruction (ACLR); yet little is known about the association between joint loading due to daily walking and cartilage health post‐ACLR. Accelerometer‐based measures of daily steps and cadence (i.e., rate of steps/min) provide information regarding daily walking in a real‐world setting. The purpose of this study was to determine the association between changes in serum cartilage oligomeric matrix protein (COMP; %∆COMP), a mechanosensitive biomarker that is associated with osteoarthritis progression, following a standardized walking protocol and daily walking in individuals with ACLR and uninjured controls. Daily walking was assessed over 7 days using an accelerometer worn on the right hip in 31 individuals with ACLR and 21 controls and quantified as mean steps/day and time spent in ≥100 steps/min. Serum COMP was measured before and following a 3000‐step walking protocol at a preferred speed. %∆COMP was calculated as a change in COMP relative to the prewalking value. Linear regressions were used to examine associations between daily walking and %∆COMP after adjusting for preferred speed. Fewer daily steps (ΔR2 = 0.18, p = 0.02) and fewer minutes spent in ≥100 steps/min (ΔR2 = 0.16, p = 0.03) were associated with greater %∆COMP following walking in individuals with ACLR; no statistically significant associations existed in controls (daily steps: ΔR2 = 0.03, p = 0.47; time ≥100 steps/min: ΔR2 < 0.01, p = 0.81). Clinical significance: Individuals with ACLR who engage in less daily walking undergo greater %ΔCOMP, which may represent greater cartilage degradation or turnover in response to walking. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to examine the effects of fatiguing power loading on neuromuscular properties, force production, and metabolic capacities during four phases of the menstrual cycle (MC): menstruation (M), midfollicular (mid FOL), ovulation (OV), and midluteal (mid LUT). Methods: Sixteen eumenorrheic women performed sessions of maximal explosive leg press (2 × 10 at 60% one-repetition maximum load with 2-min recovery between sets). Serum hormones and neuromuscular responses were measured. Results: The loading protocol significantly decreased power (between −14.2% and −12.5%; P < 0.001) and maximal force production (between maximum voluntary force (MVC); −15.0% and −7.8%; P < 0.001–0.05), while decreasing activation level (between AL; −6.9% and −2.2%; P < 0.001–0.05) in all MC phases. The decreases in AL were greater during mid LUT (P < 0.01) compared with OV. Changes in MVC and AL were associated (r 2 = 0.53; P < 0.01) at all MC phases. The decrease in EMG during MVC did not differ between the MC phases; however, mean power frequency was higher during M (+7.7%; P < 0.05) and mid LUT (+3.1%; P < 0.05) compared with OV (−7.5%). Resting twitch force decreased during mid FOL (−6.9%; P < 0.05) and mid LUT (−16.2%; P < 0.001), and these values were significantly decreased (P < 0.05) compared with OV. In addition, resting twitch force at mid LUT was lower (P < 0.01) compared with M. Blood lactate levels increased more (P < 0.05) during M compared with mid LUT. Some serum hormone concentrations were associated with fatigue-induced changes in neuromuscular properties and force production, but these correlations behaved differently between the MC phases. Conclusions: OV may offer a more favorable hormonal milieu for acute neural responses, whereas mid FOL and mid LUT seem to be superior for acute muscular responses. [ABSTRACT FROM AUTHOR]

The energy costs of athletic training can be substantial, and deficits arising from costs unmet by adequate energy intake, leading to a state of low energy availability, may adversely impact athlete health and performance. Life history theory is a branch of evolutionary theory that recognizes that the way the body uses energy—and responds to low energy availability—is an evolved trait. Energy is a finite resource that must be distributed throughout the body to simultaneously fuel all biological processes. When energy availability is low, insufficient energy may be available to equally support all processes. As energy used for one function cannot be used for others, energetic "trade-offs" will arise. Biological processes offering the greatest immediate survival value will be protected, even if this results in energy being diverted away from others, potentially leading to their downregulation. Athletes with low energy availability provide a useful model for anthropologists investigating the biological trade-offs that occur when energy is scarce, while the broader conceptual framework provided by life history theory may be useful to sport and exercise researchers who investigate the influence of low energy availability on athlete health and performance. The goals of this review are: (1) to describe the core tenets of life history theory; (2) consider trade-offs that might occur in athletes with low energy availability in the context of four broad biological areas: reproduction, somatic maintenance, growth, and immunity; and (3) use this evolutionary perspective to consider potential directions for future research. [ABSTRACT FROM AUTHOR]

Background: Ageing is accompanied by decreases in physical capacity and physiological regulatory mechanisms including altered hormonal regulation compared with age-matched sedentary people. The potential benefits of exercise in restoring such altered hormone production and secretion compared to age-matched physically inactive individuals who are ageing remains unclear. Objectives: The aim of this systematic review was to summarise the findings of exercise training in modulating levels of ostensibly anabolic and catabolic hormones in adults aged > 40 years. Methods: We searched the following electronic databases (to July 2021) without a period limit: Cochrane Library, PubMed, Science Direct, Scopus, SPORTDiscus and Web of Science. Additionally, a manual search for published studies in Google Scholar was conducted for analysis of the 'grey literature' (information produced outside of traditional commercial or academic publishing and distribution channels). The initial search used the terms 'ageing' OR 'advanced age' OR 'old people' OR 'older' OR elderly' AND 'anabolic hormones' OR 'catabolic hormones' OR 'steroid hormones' OR 'sex hormones' OR 'testosterone' OR 'cortisol' OR 'insulin' OR 'insulin-like growth factor-1' OR 'IGF-1' OR 'sex hormone-binding globulin' OR 'SHBG' OR 'growth hormone' OR 'hGH' OR 'dehydroepiandrosterone' OR 'DHEA' OR 'dehydroepiandrosterone sulfate (DHEA-S)' AND 'exercise training' OR 'endurance training' OR 'resistance training' OR ' strength training' OR 'weight-lifting' OR 'high-intensity interval training' OR 'high-intensity interval exercise' OR 'high-intensity intermittent training' OR 'high-intensity intermittent exercise' OR 'interval aerobic training' OR 'interval aerobic exercise' OR 'intermittent aerobic training' OR 'intermittent aerobic exercise' OR 'high-intensity training' OR 'high-intensity exercise' OR 'sprint interval training' OR 'sprint interval exercise' OR 'combined exercise training' OR 'anaerobic training'. Only eligible full texts in English or French were considered for analysis. Results: Our search identified 484 records, which led to 33 studies for inclusion in the analysis. Different exercise training programs were used with nine studies using endurance training programs, ten studies examining the effects of high-intensity interval training, and 14 studies investigating the effects of resistance training. Most training programs lasted ≥ 2 weeks. Studies, regardless of the design, duration or intensity of exercise training, reported increases in testosterone, sex hormone-binding globulin (SHBG), insulin-like growth factor-1 (IGF-1), human growth hormone (hGH) or dehydroepiandrosterone (DHEA) (effect size: 0.19 < d < 3.37, small to very large) in both older males and females. However, there was no consensus on the effects of exercise on changes in cortisol and insulin in older adults. Conclusion: In conclusion, findings from this systematic review suggest that exercise training increases basal levels of testosterone, IGF-1, SHBG, hGH and DHEA in both male and females over 40 years of age. The increases in blood levels of these hormones were independent of the mode, duration and intensity of the training programs. However, the effects of long-term exercise training on cortisol and insulin levels in elderly people are less clear. [ABSTRACT FROM AUTHOR]

We investigated the effects of 12 weeks of high-intensity interval training (HIIT) on selected circulating adipokines and other cardiovascular diseases risks factors in men with obesity. Thirty men with obesity (age: 24.96±3.11 year, BMI: 30.92±1.04 kg/m2) were randomly assigned to HIIT and control groups. The HIIT group participated in a 12-week HIIT program (5×2 min interval bout at an intensity of 85–95% HRmax interspersed by 1 min passive recovery, three times per week), while the control group maintained their usual lifestyles. Blood lipids, insulin resistance, and select serum adipokines were assessed before and after 12 weeks of the intervention period. HIIT improved body composition and lipid profiles (p<0.05) and also decreased fasting insulin levels (p=0.001) and HOMA-IR (p=0.002) levels. Furthermore, HIIT increased levels of lipocalin-2 (p=0.002) while decreasing omentin-1 levels (p=0.001) in men with obesity. Changes in lcn2 and omentin-1 concentrations correlated with the changes in risk factors in the HIIT group (p<0.05). The results indicate that 12 weeks of supervised HIIT significantly improves both circulating concentrations of lcn2 and omentin-1, two recently described adipokines, and risk markers of cardiovascular diseases in men with obesity. Further research is necessary to understand the molecular mechanisms involved with these changes. [ABSTRACT FROM AUTHOR]

Context: Of the individuals able to return to sport participation after an anterior cruciate ligament(ACL) injury, up to 25% will experience a second ACL injury. This population may be more sensitive to hormonal fluctuations, which may explain this high rate of second injury. Objective: To examine changes in 3-dimensional hip and knee kinematics and kinetics during a jump landing and to examine knee laxity across the menstrual cycle in women with histories of unilateral noncontact ACL injury. Design: Controlled laboratory study. Setting: Laboratory. Patients or Other Participants: A total of 20 women (age= 19.6 ± 1.3 years, height = 168.6 ± 5.3 cm, mass = 66.2 ± 9.1 kg) with unilateral, noncontact ACL injuries. Intervention(s): Participants completed a jump-landing task and knee-laxity assessment 3 to 5 days after the onset of menses and within 3 days of a positive ovulation test. Main Outcome Measure(s): Kinematics in the uninjured limb at initial contact with the ground during a jump landing, peak kinematics and kinetics during the loading phase of landing, anterior knee laxity via the KT-1000, peak vertical ground reaction force, and blood hormone concentrations (estradiol-β-17, progesterone, free testosterone). Results: At ovulation, estradiol-β-17 (t = -2.9, P = .009), progesterone (t =-3.4, P = .003), and anterior knee laxity (t = -2.3, P = .03) increased, and participants presented with greater knee-valgus moment (Z = -2.6, P = .01) and femoral internal rotation (t =-2.1, P = .047). However, during the menses test session, participants landed harder (greater peak vertical ground reaction force; t = 2.2, P = .04), with the tibia internally rotated at initial contact (t = 2.8, P = .01) and greater hip internal-rotation moment (Z = -2.4, P = .02). No other changes were observed across the menstrual cycle. Conclusions: Knee and hip mechanics in both phases of the menstrual cycle represented a greater potential risk of ACL loading. Observed changes in landing mechanics may explain why the risk of second ACL injury is elevated in this population. [ABSTRACT FROM AUTHOR]

PURPOSE: Sports medicine professionals commonly describe two functionally different units of the vastus medialis (VM), the VM, and the vastus medialis oblique (VMO), but the anatomical support is equivocal. The functional difference of the VMO is principle to rehabilitation programs designed to alleviate anterior knee pain, a pathology that is known to have a greater occurrence in women. The purpose of this study was to determine whether the motor units of the VM and VMO are differentially recruited and if this recruitment pattern has an effect of sex or menstrual cycle phase. METHODS: Single motor unit recordings from the VM and VMO were obtained for men and women during an isometric ramp knee extension. Eleven men were tested once. Seven women were tested during five different phases of the menstrual cycle, determined by basal body temperature mapping. The recruitment threshold and the initial firing rate at recruitment were determined from 510 motor unit recordings. RESULTS: The initial firing rate was lower in the VMO than that in the VM in women (P < 0.001) but not in men. There was no difference in recruitment thresholds for the VM and VMO in either sex or across the menstrual cycle. There was a main effect of menstrual phase on initial firing rate, showing increases from the early follicular to late luteal phase (P = 0.003). The initial firing rate in the VMO was lower than that in the VM during ovulatory (P = 0.009) and midluteal (P = 0.009) phases. CONCLUSION: The relative control of the VM and VMO changes across the menstrual cycle. This could influence patellar pathologies that have a higher incidence in women. [ABSTRACT FROM AUTHOR]

The objective of present study is to investigate the effects of walk training with and without blood flow restriction (BFR and no-BFR) on lipid profiles, inflammatory and haematological factors in over-weighed men. Participants were divided into BFR (n = 9) or no-BFR (n = 9) groups. Both groups were exposed to 8-week walk training on a treadmill: 3 sessions/week at a speed of 50 m/min, 5 sets × 2 min/session. There were differences in pre- to post-levels of (TG) and fibrinogen in the BFR group (p ≤ 0.05) that were accompanied by changes in red blood cells (RBC), haemoglobin (HGB) and haematocrit (HCT) levels (p ≤ 0.05). RBC levels were increased in the BFR group (p ≤ 0.05). The groups differed in their mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC). These findings suggest the efficiency of BFR walk training in individuals exposed to chronic diseases associated with overweight, such as metabolic syndrome. [ABSTRACT FROM AUTHOR]

This study evaluated the associations of adipokines with cardiovascular risk factors. Subjects/Methods: 60 normal weight (BMI ≤75th percentile) and 60 overweight (BMI ≥95th percentile) adolescents aged 10-14 years. Resting systolic and diastolic blood pressures (SBP, DBP) and waist circumference were obtained in duplicate. Circulating adiponectin, resistin, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), total cholesterol (TC), high-density lipoprotein (HDL), and triglycerides (TG) were measured from fasting plasma samples. Results: Simple correlations showed that SBP was significantly related (p < 0.05) to adiponectin (r = -0.185), resistin (r = 0.207), and IL-6 (r = 0.238); HDL was significantly related to adiponectin (r = 0.398) and TNF-α (r = -0.227). TG was only related to adiponectin (r = -0.292, p < 0.05). Multiple regression models controlling for puberty and ethnicity indicated that adiponectin (R2 = 0.152, p < 0.05), resistin (R2 = 0.152, p < 0.05), and IL-6 (R2 = 0.170, p < 0.05) were associated with SBP. The association between adiponectin and HDL was stronger in normal weight versus overweight adolescents (R2 = 0.336, p < 0.05). None of the other models showed differences in the associations by weight status. Conclusions: In adolescents, SBP but not DBP was associated with most adipokines. HDL, but not TC, was also associated with some adipokines. TG were only associated with adiponectin. Associations were mostly related to adiposity. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objective: While acute alterations in leptin, insulin, cortisol and growth hormone (GH) levels have been reported in children following weight change interventions, little is known about natural hormonal changes as children grow and how these changes are affected by unprovoked weight status changes. The purpose of this investigation was to compare changes in leptin, insulin, cortisol and GH levels in youth who maintained their weight status vs. those who moved from normal weight to overweight or vice versa. Methods: Data were collected from 120 youth at baseline (9.8±1.0 years) and two years later. Participants were selected from a larger cohort to represent all scenarios of weight status: normal weight [>5th and <85th body mass index (BMI) percentile] at both time points (NN), overweight (⩾85th BMI percentile) at both time points (OO), normal weight status who changed to overweight (NO) and overweight status which changed to normal weight (ON). Hormonal concentrations were measured from fasting venous blood. Results: In youth who changed their weight status, there were significant associations (p<0.05) between changes in BMI percentile and changes in leptin, insulin and cortisol (partial R2= 0.35, 0.13 and 0.11, respectively), after accounting for race, sex and changes in pubertal status and aerobic power. Our key findings were that youth who became overweight (NO) showed greater changes for leptin (+205% vs. -21%) and cortisol (-33% vs. +13%), p<0.05 than those who reverted from overweight to normal weight (ON). Conclusion: Natural changes in weight status in youth show a relationship with changes in leptin, insulin and cortisol levels and the hormonal changes appear to be more sensitive to increases, rather than reductions, in weight status. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if the ingestion of sodium citrate (CIT) alters blood levels of fluid and electrolyte regulatory hormones at rest and during exercise. Using a randomized, double-blinded, crossover design, 13 young, male well-trained runners performed continuous incremental running tests to volitional exhaustion on a treadmill 2 h after ingestion of 0.5 g·kg-1 body mass of CIT or placebo (PLC) in 1000 mL of solution. These trials were separated by 2 weeks. Baseline (before ingestion) aldosterone concentration did not differ between the 2 trials; however, it was 36.5% (p = 0.003) lower in the CIT trial compared with the PLC trial before the running test (i.e., after ingestion). The extent of the running-induced increase in aldosterone was 33% (p = 0.009) smaller in the CIT trial. There were no between-trial differences in the levels of adrenocorticotropic hormone, N-terminal pro-B-type natriuretic peptide, or renin activity at any stage of the study. However, a greater relative increase in plasma volume (mean ± SD, 6.41% ± 3.78% vs. 4.08% ± 3.33%; p = 0.042) was observed after administering the CIT compared with the PLC drink. Serum Na+ concentration increased (by 3.1 ± 1.2 mmol·L-1; p < 0.0001) after ingestion of the CIT but not the PLC drink. A higher Na+ level was observed in the CIT trial than in the PLC trial (142.4 ± 1.6 vs. 139.3 ± 1.4 mmol·L-1, p = 0.00001) after completion of the run. In conclusion, pre-exercise ingestion of CIT induces a decrease in serum aldosterone concentration in the resting condition and a blunting of the aldosterone response during incremental running exercise to volitional exhaustion. The observed effect of CIT on the serum aldosterone level may be mediated by an acute increase in plasma volume and serum Na+ concentration alterations. Cette étude se propose de vérifier si la consommation de citrate de sodium (CIT) modifie les taux des hormones responsables de l’équilibre hydrique et des électrolytes, au repos et à l’effort. Treize jeunes hommes bien entraînés à la course participent à un test d’effort progressif continu sur tapis roulant, jusqu’à épuisement, et ce, 2 h après avoir consommé 0,5 g·kg-1 de masse corporelle de CIT ou d’un placebo (PLC) dissous dans 1000 mL d’une solution. La stratégie de recherche consiste en un plan expérimental contrebalancé à double insu. Les deux essais sont réalisés à deux semaines d’intervalle. D’un essai à l’autre, la concentration d’aldostérone de référence avant la consommation de la boisson ne diffère pas; par contre, elle diminue de 36,5 % (p = 0,003) après la consommation de la boisson dans la condition CIT comparativement à la condition PLC avant le début du test. Dans la condition CIT, l’augmentation de la concentration d’aldostérone suscitée par la course est 33 % plus faible (p = 0,009). D’une condition à l’autre et à toutes les étapes de l’étude, on n’observe aucune différence des concentrations de l’hormone adrénocorticotrope, du fragment N-terminal du peptide natriurétique pro-B et de l’activité de la rénine. Cependant, on observe une plus grande augmentation du volume plasmatique relatif après la consommation du CIT comparativement à la consommation du PLC : moyenne ± écart-type, 6,41 ± 3,78 % comparativement à 4,08 ± 3,33 %; p = 0,042. La concentration sérique de Na+ augmente de 3,1 ± 1,2 mmol·L-1 (p < 0,0001) après la consommation du CIT, mais n’augmente pas après la consommation du PLC. Après la fin de la course, on observe une plus grande concentration de Na+ dans la condition CIT que dans la condition PLC : 142,4 ± 1,6 mmol·L-1 comparativement à 139,3 ± 1,4 mmol·L-1 (p = 0,00001). En conclusion, la consommation de CIT avant le début de l’exercice physique suscite une diminution de la concentration sérique d’aldostérone au repos et une atténuation de la réponse de l’aldostérone au cours du test d’effort progressif jusqu’à épuisement. L’effet noté du CIT sur la concentration sérique d’aldostérone est probablement dû à l’augmentation rapide du volume plasmatique et à la modification du taux sérique de Na+. [ABSTRACT FROM AUTHOR]

This study examined the effect of dietary carbohydrate (CHO) consumption on the free testosterone to cortisol (fTC) ratio during a short-term intense micro-cycle of exercise training. The fTC ratio is a proposed biomarker for overreaching-overtraining (i.e., training stress or imbalance) in athletes. The ratio was studied in two groups, control-CHO (approximately 60% of daily intake, n = 12) and low-CHO (approximately 30% of daily intake, n = 8), of male subjects who performed three consecutive days of intensive training (approximately 70-75% maximal oxygen consumption, 60 min per day) with a dietary intervention (on the day before and during training). Resting, pre-exercise blood samples were collected under standardized-controlled conditions before each day of training (Pre 1, 2, 3) and on a fourth day after the micro-cycle (Rest). Bloods were analyzed for free testosterone and cortisol via radioimmunoassay procedures. Subjects performed no additional physical activity other than prescribed training. Statistical analysis (ANCOVA) revealed the fTC ratio decreased significantly (p < 0.01) from pre-study resting measurement (Pre 1) to the final post-study resting measurement (Rest) in the low-CHO group (-43%), but no change occurred (p > 0.05) in the control-CHO group (-3%). Findings suggest if the fTC ratio is utilized as a marker of training stress or imbalance it is necessary for a moderately high diet of CHO to be consumed to maintain validity of any observed changes in the ratio value. [ABSTRACT FROM AUTHOR]

Until recently, there has been less demand for and interest in female-specific sport and exercise science data. As a result, the vast majority of high-quality sport and exercise science data have been derived from studies with men as participants, which reduces the application of these data due to the known physiological differences between the sexes, specifically with regard to reproductive endocrinology. Furthermore, a shortage of specialist knowledge on female physiology in the sport science community, coupled with a reluctance to effectively adapt experimental designs to incorporate female-specific considerations, such as the menstrual cycle, hormonal contraceptive use, pregnancy and the menopause, has slowed the pursuit of knowledge in this field of research. In addition, a lack of agreement on the terminology and methodological approaches (i.e., gold-standard techniques) used within this research area has further hindered the ability of researchers to adequately develop evidenced-based guidelines for female exercisers. The purpose of this paper was to highlight the specific considerations needed when employing women (i.e., from athletes to non-athletes) as participants in sport and exercise science-based research. These considerations relate to participant selection criteria and adaptations for experimental design and address the diversity and complexities associated with female reproductive endocrinology across the lifespan. This statement intends to promote an increase in the inclusion of women as participants in studies related to sport and exercise science and an enhanced execution of these studies resulting in more high-quality female-specific data. [ABSTRACT FROM AUTHOR]

This study investigated the effect of oral contraceptive (OC) use on acute changes in steroid hormone concentrations and tryptophan (TRP) metabolites in response to strength exercise. Twenty-one women (age: 23 ± 3 years), 8 combined OC users (OC group) and 13 naturally cycling women (menstrual cycle [MC] group), participated. Testing was performed during the pill-free interval for the OC group and the follicular phase for the MC group. Subjects completed an intense strength exercise protocol (4 x 10 repetitions back squat). Blood samples were taken at baseline (T0), post-exercise (T1), and after 24 hours (T2) to determine serum concentrations of cortisol, estradiol, testosterone, TRP, and kynurenine (KYN). Statistical significance was defined asp <0.05. At T0, the OC group showed higher cortisol (OC: 493.7 ± 47.1 ng⋅ml-1, MC: 299.1 ± 62.7 ng⋅ml-1, p < 0.001) and blood lactate(OC: 1.81 ±0.61 mmol⋅L-1, MC: 1.06 ± 0.30 mmol⋅L-1, p = 0.001) and lower estradiol (OC: 31.12 ± 4.24 pg⋅mL-1, MC: 38.34 ± 7.50 pg⋅mL-1, p = 0.023) and KYN (OC: 1.15 ± 0.23 μmol⋅L-1, MC: 1.75 ± 0.50 μmol⋅L-1, p = 0.005). No significant interactions (group x time, p> 0.05) were found for the hormones and TRP metabolites assessed. Oral contraceptive use did not affect the physiological response of steroid hormones and TRP metabolites to acute strength exercise during the low hormone phase of the contraceptive or MC in healthy young women, even when some baseline concentrations differed between groups. Consequently, these findings provide important implications for practitioners testing heterogeneous groups of female athletes. [ABSTRACT FROM AUTHOR]

Mooses, M, Haile, DW, Ojiambo, R, Sang, M, Mooses, K, Lane, AR, and Hackney, AC. Shorter ground contact time and better running economy: evidence from female Kenyan runners. J Strength Cond Res 35(2): 481-486, 2021-Previously, it has been concluded that the improvement in running economy (RE) might be considered as a key to the continued improvement in performance when no further increase in V̇o2max is observed. To date, RE has been extensively studied among male East African distance runners. By contrast, there is a paucity of data on the RE of female East African runners. A total of 10 female Kenyan runners performed 3 × 1,600-m steady-state run trials on a flat outdoor clay track (400-m lap) at the intensities that corresponded to their everyday training intensities for easy, moderate, and fast running. Running economy together with gait characteristics was determined. Subjects showed moderate to very good RE at the first (202 ± 26 ml·kg-1·km-1) and second (188 ± 12 ml·kg-1·km-1) run trials, respectively. Correlation analysis revealed significant relationship between ground contact time (GCT) and RE at the second run (r = 0.782; p = 0.022), which represented the intensity of anaerobic threshold. This study is the first to report the RE and gait characteristics of East African female athletes measured under everyday training settings. We provided the evidence that GCT is associated with the superior RE of the female Kenyan runners. [ABSTRACT FROM AUTHOR]

Field-based, portable motion-capture systems can be used to help identify individuals at greater risk of lower extremity injury. Microsoft Kinect-based markerless motion-capture systems meet these requirements; however, until recently, these systems were generally not automated, required substantial data postprocessing, and were not commercially available. To validate the kinematic measures of a commercially available markerless motion-capture system. Descriptive laboratory study. Laboratory. A total of 20 healthy, physically active university students (10 males, 10 females; age = 20.50 ± 2.78 years, height = 170.36 ± 9.82 cm, mass = 68.38 ± 10.07 kg, body mass index = 23.50 ± 2.40 kg/m2). Participants completed 5 jump-landing trials. Kinematic data were simultaneously recorded using Kinect-based markerless and stereophotogrammetric motion-capture systems. Sagittal- and frontal-plane trunk, hip-joint, and knee-joint angles were identified at initial ground contact of the jump landing (IC), for the maximum joint angle during the landing phase of the initial landing (MAX), and for the joint-angle displacement from IC to MAX (DSP). Outliers were removed, and data were averaged across trials. We used intraclass correlation coefficients (ICCs [2,1]) to assess intersystem reliability and the paired-samples t test to examine mean differences (α ≤.05). Agreement existed between the systems (ICC range = −1.52 to 0.96; ICC average = 0.58), with 75.00% (n = 24/32) of the measures being validated (P ≤.05). Agreement was better for sagittal- (ICC average = 0.84) than frontal- (ICC average = 0.35) plane measures. Agreement was best for MAX (ICC average = 0.77) compared with IC (ICC average = 0.56) and DSP (ICC average = 0.41) measures. Pairwise comparisons identified differences for 18.75% (6/32) of the measures. Fewer differences were observed for sagittal- (0.00%; 0/15) than for frontal- (35.29%; 6/17) plane measures. Between-systems differences were equivalent for MAX (18.18%; 2/11), DSP (18.18%; 2/11), and IC (20.00%; 2/10) measures. The markerless system underestimated sagittal-plane measures (86.67%; 13/15) and overestimated frontal-plane measures (76.47%; 13/17). No trends were observed for overestimating or underestimating IC, MAX, or DSP measures. Moderate agreement existed between markerless and stereophotogrammetric motion-capture systems. Better agreement existed for larger (eg, sagittal-plane, MAX) than for smaller (eg, frontal-plane, IC) joint angles. The DSP angles had the worst agreement. Markerless motion-capture systems may help clinicians identify individuals at greater risk of lower extremity injury. [ABSTRACT FROM AUTHOR]