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Background: Spiroergometry is important for modern performance diagnostics, and reference values have been evaluated for bicycle and treadmill ergometers. The aim of this study is to assess the comparability of bicycle and hand-crank spiroergometry and its associated parameters, as hand-crank spiroergometry can be used during rehabilitation in patients with definitive or temporally impairment of the lower extremity. Methods: Thirty-seven healthy volunteers completed 2 exhausting performance diagnostics on hand-crank and bicycle spiroergometry. Participants' anthropometric characteristics, maximum power, multiple exertion criteria, maximum aerobic capacity, and maximum heart rate were detected, and ventilatory and metabolic thresholds were determined. Results: The maximum power, maximum heart rate, maximum aerobic capacity, and ventilatory thresholds were significant higher on the bicycle ergometer (P <.001). The metabolic thresholds occurred on higher lactate values on the hand-crank ergometer. Equations for calculating maximum aerobic capacity from the maximum power measured in either hand-crank or bicycle ergometer could be found through regression analysis. Conclusions: Although there are problems in interpreting results of different ergometries due to severe physiology differences, the equations can be used for patients who are temporally unable to complete the established ergometry due to a deficit in the lower extremity. This could improve training recommendations for patients and para-athletes in particular. [ABSTRACT FROM AUTHOR]

This study aimed to determine whether caffeine gum influenced perceptual-cognitive and physical performance during the extra-time period of simulated soccer match-play. Semiprofessional male soccer players (n = 12, age: 22 ± 3 years, stature: 1.78 ± 0.06 m, mass: 75 ± 9 kg) performed 120-min soccer-specific exercise on two occasions. In a triple-blind, randomized, crossover design, players chewed caffeinated (200 mg; caffeine) or control (0 mg; placebo) gum for 5 min following 90 min of soccer-specific exercise. Perceptual-cognitive skills (i.e., passing accuracy, reaction time, composure, and adaptability) were assessed using a soccer-specific virtual reality simulator, collected pre- and posttrial. Neuromuscular performance (reactive-strength index, vertical jump height, absolute and relative peak power output, and negative vertical displacement) and sprint performance (15 and 30 m) were measured at pretrial, half-time, 90 min, and posttrial. Caffeine gum attenuated declines in reaction time (pre: 90.8 ± 0.8 AU to post: 90.7 ± 0.8 AU) by a further 4.2% than placebo (pre: 92.1 ± 0.8 AU to post: 88.2 ± 0.8 AU; p <.01). Caffeine gum reduced composure by 4.7% (pre: 69.1 ± 0.8 AU to post: 65.9 ± 0.8 AU) versus placebo (pre: 68.8 ± 0.8 AU to post: 68.3 ± 0.8 AU; p <.01). Caffeine gum did not influence any other variables (p >.05). Where caffeine gum is consumed by players prior to extra-time, reaction time increases but composure may be compromised, and neuromuscular and sprint performance remain unchanged. Future work should assess caffeine gum mixes with substances like L-theanine that promote a relaxed state under stressful conditions. [ABSTRACT FROM AUTHOR]

This study investigated the test–retest reliability of running economy (RE) and metabolic and cardiorespiratory parameters related to endurance running performance using a multistage incremental treadmill test. On two occasions separated by 21–28 days, 12 male middle- and long-distance runners ran at 10, 11, 12, 13, and 14 km/hr for 8 min each stage, immediately followed by a ramp test to volitional exhaustion. Carbohydrate (10% maltodextrin solution) was consumed before and during the test to provide ∼1 g/min of exercise. RE, minute ventilation ( V ˙ E), oxygen consumption ( V ˙ O 2 ), carbon dioxide production ( V ˙ CO 2 ), respiratory exchange ratio (RER), heart rate (HR), ratings of perceived exertion (RPE), and blood glucose and lactate concentrations were recorded for each stage and at volitional exhaustion. Time-to-exhaustion (TTE) and peak oxygen consumption ( V ˙ O 2 peak) during the ramp test were also recorded. Absolute reliability, calculated as the coefficient of variation (CV) between repeated measures, ranged from 2.3% to 3.1% for RE, whereas relative reliability, calculated as the intraclass correlation coefficient (ICC), ranged from.42 to.79. V ˙ E , V ˙ O 2 , V ˙ O 2 peak , V ˙ CO 2 , RER, and HR had a CV of 1.1%–4.3% across all stages. TTE and RPE had a CV of 7.2% and 2.3%–10.8%, respectively, while glucose and lactate had a CV of 4.0%–17.8%. All other parameters, except for blood glucose, were demonstrated to have good-to-excellent relative reliability assessed by ICC. Measures of RE, V ˙ O 2 peak , and TTE were reliable during this two-phase multistage incremental treadmill test in a cohort of trained and highly trained male middle- and long-distance runners. [ABSTRACT FROM AUTHOR]

The main objective of this placebo-controlled, triple-blind, balanced crossover study was to assess the acute effects of phenylcapsaicin (PC) intake (2.5 mg) on intraocular pressure (IOP), ocular perfusion pressure (OPP), and heart rate (HR) during a 30-min cycling task performed at 15% of the individual maximal power. Twenty-two healthy young adults performed the cycling task 45 min after ingesting PC or placebo. IOP was measured with a rebound tonometer before exercise, during cycling (every 6 min), and after 5 and 10 min of recovery. OPP was assessed before and after exercise. HR was monitored throughout the cycling task. We found an acute increase of IOP levels related to PC consumption while cycling (mean difference = 1.91 ± 2.24 mmHg; p =.007, η p 2 =.30), whereas no differences were observed for OPP levels between the PC and placebo conditions (mean difference = 1.33 ± 8.70 mmHg; p =.608). Mean HR values were higher after PC in comparison with placebo intake (mean difference = 3.11 ± 15.87 bpm, p =.019, η p 2 =.24), whereas maximum HR did not differ between both experimental conditions (p =.199). These findings suggest that PC intake before exercise should be avoided when reducing IOP levels is desired (e.g., glaucoma patients or those at risk). Future studies should determine the effects of different ergogenic aids on IOP and OPP levels with other exercise configurations and in the long term. [ABSTRACT FROM AUTHOR]

Purpose: To examine associations between exercise heart rate (HRex) during a continuous-fixed submaximal fitness test (CF-SMFT) and an intermittent-variable protocol (semistandardized kicking drill [SSD]) in Australian Football athletes, controlling for external intensities, within-session scheduling, and environmental conditions. Methods: Forty-four professional male Australian Football athletes (22.8 [8.0] y) were monitored over 10 sessions involving a 3-minute CF-SMFT (12 km·h−1) as the first activity and a SSD administered 35.7 (8.0) minutes after the CF-SMFT. Initial heart rate and HRex were collected, with external intensities measured as average velocity (in meters per minute) and average acceleration–deceleration (in meters per second squared). Environmental conditions were sampled. A penalized hierarchical linear mixed model was tuned for a Bayesian information criterion minima using a 10-fold cross-validation, with out-of-sample prediction accuracy assessed via root-mean-squared error. Results: SSD average acceleration–deceleration, initial heart rate, temperature, and ground hardness were significant moderators in the tuned model. When model covariates were held constant, a 1%-point change in SSD HRex associated with a 0.4%-point change in CF-SMFT HRex (95% CI, 0.3–0.5). The tuned model predicted CF-SMFT HRex with an average root-mean-squared error of 2.64 (0.57) over the 10-fold cross-validation, with 74% and 86% of out-of-sample predictions falling within 2.7%-points and 3.7%-points, respectively, from observed values, representing the lower and upper limits for detecting meaningful changes in HRex according to the documented typical error. Conclusions: Our findings support the use of an SSD to monitor physiological state in Australian Football athletes, despite varied scheduling within session. Model predictions of CF-SMFT HRex from SSD HRex closely aligned with observed values, considering measurement imprecision. [ABSTRACT FROM AUTHOR]

Context: Blood flow restriction resistance exercise studies often require caffeine abstinence to avoid cardiovascular effects that could change the blood flow restriction stimulus. However, effects may be attenuated for habituated users. Objective: To compare cardiovascular responses to blood flow restriction resistance exercise when habituated users consume or abstain from caffeine. Design: Thirty participants completed a 3-visit within-subject study beginning with familiarization and caffeine intake questionnaire. Methods: Visits 2 and 3 consisted of blood flow restriction resistance exercise (3 sets bicep curls to failure, 30% 1-repetition max, 40% arterial occlusion pressure [AOP]), following participants' normal caffeine consumption (CAFF) or abstaining (ABS). AOP, systolic (SBP) and diastolic (DBP) blood pressure, and heart rate were measured preexercise and postexercise. Prevalues and preexercise to postexercise change scores for SBP, DBP, AOP (all millimeters of mercury), heart rate (in beats per minute), and repetitions were compared between conditions. Results are represented as mean (SD). Results: Preexercise AOP was similar for CAFF (137.8 [14.4]) and ABS (137.1 [14.9], BF10 = 0.2), although pre-SBP was higher for CAFF (115.4 [9.8]) than ABS (112.3 [9.4], BF10 = 1.9). Pre-DBP was similar between conditions. The exercise-induced change in AOP was greater for CAFF (18.4 [11.2]) than ABS (13.2 [14.9]), though evidence was anecdotal (BF10 = 0.7). Exercise-induced changes in SBP, DBP, and heart rate were similar between conditions (all BF10 ≤ 0.40). More repetitions were completed for CAFF (63 [26]) than ABS (57 [17], BF10 = 2.1). Conclusions: The findings of this study suggest that for habituated users, maintaining daily caffeine habits will not have substantial effects on common cardiovascular variables relevant to blood flow restriction. [ABSTRACT FROM AUTHOR]

Purpose: To compare the standard Yo-Yo intermittent recovery (IR) test and an agility Yo-Yo IR test with a higher number of change-of-direction movements to cardiorespiratory match performance. Methods: The study included 11 professional male handball players (age 24.5 [4.6] y) of a German second-league team. The performance parameters of the players of the seasons 2016–17 to 2018–19 were analyzed. The Yo-Yo IR test was compared to a Yo-Yo IR test with multiple multidirectional changes of direction in response to visual stimuli, which was conducted on a SpeedCourt (Yo-Yo SC IR). Peak oxygen uptake (VO2peak) and maximum heart rate (HRmax) were measured. Between-methods differences of individual athletes were quantified with Bland–Altman plots. Results: HRmax was not statistically different during the Yo-Yo SC IR test compared to the Yo-Yo IR test (181 [10] vs 188 [8] beats·min−1; P =.16). Agreement between the 2 tests was moderate for HRmax and good for heart rates >180 beats·min−1. Mean average VO2peak was 51.7 (3.9) and 50.9 (2.8) mL·min–1·kg–1 for the Yo-Yo SC IR test and the Yo-Yo IR test (P =.693), respectively. Conclusions: A Yo-Yo test with multidirectional changes of direction in response to visual stimuli yielded good agreement with the frequently used linear running tests and can be used to assess players' VO2peak. The HRmax achieved during this test should be used with caution. [ABSTRACT FROM AUTHOR]

Purpose: To assess associations between sedentary time (ST), physical activity (PA), and cardiovascular health in early childhood. Method: Cross-sectional study including 160 children (age 6.1 y [SD 0.5], 86 boys, 93 maternal body mass index ≥ 30 kg/m2, and 73 gestational diabetes) assessed for pulse wave velocity, echocardiography, ultra-high frequency 48–70 MHz vascular ultrasound, and accelerometery. Results: Boys had 385 (SD 53) minutes per day ST, 305 (SD 44) minutes per day light PA, and 81 (SD 22) minutes per day moderate to vigorous PA (MVPA). Girls had 415 (SD 50) minutes per day ST, 283 (SD 40) minutes per day light PA, and 66 (SD 19) minutes per day MVPA. In adjusted analyses, MVPA was inversely associated with resting heart rate (β = −6.6; 95% confidence interval, −12.5 to −0.7) and positively associated with left ventricular mass (β = 6.8; 1.4–12.3), radial intima-media thickness (β = 11.4; 5.4–17.5), brachial intima-media thickness (β = 8.0; 2.0–14.0), and femoral intima-media thickness (β = 1.3; 0.2–2.3). MVPA was inversely associated with body fat percentage (β = −3.4; −6.6 to −0.2), diastolic blood pressure (β = −0.05; −0.8 to −0.1), and femoral (β = −18.1; −32.4 to −0.8) and radial (β = −13.4; −24.0 to −2.9) circumferential wall stress in boys only. ST and pulse wave velocity showed no significant associations. Conclusions: In young at-risk children, MVPA is associated with cardiovascular remodeling, partly in a sex-dependant way, likely representing physiological adaptation, but ST shows no association with cardiovascular health in early childhood. [ABSTRACT FROM AUTHOR]

Carbohydrate (CHO) supplementation during endurance exercise can improve performance. However, it is unclear whether low glycemic index (GI) CHO leads to differential ergogenic and metabolic effects compared with a standard high GI CHO. This study investigated the ergogenic and metabolic effects of CHO supplementation with distinct GIs, namely, (a) trehalose (30 g/hr), (b) isomaltulose (30 g/hr), (c) maltodextrin (60 g/hr), and (d) placebo (water). In this double-blind, crossover, counterbalanced, placebo-controlled study, 13 male cyclists cycled a total of 100 min at varied exercise intensity (i.e., 10-min stages at 1.5, 2.0, and 2.5 W/kg; repeated three times plus two 5-min stages at 1.0 W/kg before and after the protocol), followed by a 20-min time trial on four separated occasions. Blood glucose and lactate (every 20 min), heart rate, and ratings of perceived exertion were collected throughout, and muscle biopsies were taken before and immediately after exercise. The results showed that trehalose improved time-trial performance compared with placebo (total work done 302 ± 39 vs. 287 ± 48 kJ; p =.01), with no other differences between sessions (all p ≥.07). Throughout the 100-min protocol, blood glucose was higher with maltodextrin compared with the other supplements at all time points (all p <.05). Heart rate, ratings of perceived exertion, muscle glycogen content, blood glucose, and lactate were not different between conditions when considering the 20-min time trial (all p >.05). Trehalose supplementation throughout endurance exercise improved cycling performance and appears to be an appropriate CHO source for exercise tasks up to 2 hr. No ergogenic superiority between the different types of CHO was established. [ABSTRACT FROM AUTHOR]

Purpose: Successful participation in taekwondo (TKD) requires athletes to possess quick decision-making abilities and demonstrate technical proficiency during competition. Dehydration, occurring during both training and competition, is widely recognized to have various negative effects. Methods: This study investigated the impact of different levels of dehydration on cognitive function, as measured by the Vienna Test System, and the specific performance of kicking techniques among TKD athletes. Using a randomized crossover design, 12 participants were involved in the study. Before and after 1 hour of training at 80% of maximal heart rate, participants were weighed and provided urine samples. All participants were randomly assigned to 3 different hydration conditions: the euhydrated (EUH) group had unrestricted access to fluid consumption, while the hypohydrated (HYP) and severely HYP (S-HYP) groups experienced reductions of 2.0% and 4.0% of their initial body weight, respectively. Results: The EUH group exhibited better reaction speed in reaction-time test-form S1 than the HYP and S-HYP groups. Notably, the EUH group demonstrated a significantly higher success rate in the front-side kick (EUH 98%, HYP 90%, S-HYP 88%; P <.05). However, the success rates of back roundhouse kick and free head kick were similar among the 3 statuses. Furthermore, postexercise heart rates were found to be significantly higher in the HYP and S-HYP groups compared with the EUH group. Conclusions: This study provides insight into the negative effects of dehydration on cognitive function and TKD-specific performance. It is recommended that TKD athletes maintain optimal hydration levels during training and competition to ensure optimal performance. [ABSTRACT FROM AUTHOR]

Physical function is regarded as the cornerstone of healthy aging, and exercise is an important determinant of healthy aging. This study examined the feasibility and physiological (heart rate, blood pressure, blood lactate, and rate of perceived exertion) and psychological (enjoyment) response resulting from an acute progressive sled-push (SLP) exercise session using the novel XPO Sled Trainer in older adults and compared that with walking (WKC) condition. The exercise session comprised six exercise bouts at 75%, 85%, 100% (2×), and 125% (2×) of normal velocity with a 2-min rest between bouts. Thirty-six older adults were randomly allocated into either the SLP or WKC conditions. No adverse events were observed during the exercise session, and all participants completed the exercise protocol as prescribed. One-third of the participants in the SLP group reported minimal body discomfort. Significantly higher responses were observed for all physiological variables as the intensity of the exercise increased in the SLP group compared with the WKC group (p <.001). The SLP group presented a decline in enjoyment as the intensity of the exercise increased (during), but similar enjoyment level than the WKC group for the overall exercise session (p =.711). Our findings support the viability and safety of SLP exercise using the XPO Sled Trainer in older adults. Such exercise demonstrated an intensity-driven modality that may have potential to elucidate positive adaptations in the cardiovascular system of older adults with acceptable levels of enjoyment. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed at evaluating the effect of level of competition and drill typology on loads during the preseason period in male volleyball players. Methods: Internal (percentage of peak heart rate [HR] and summated HR zone) and external (PlayerLoad per minute, total and high accelerations per minute [tACCmin and hACCmin], decelerations per minute [tDECmin and hDECmin], and jumps per minute [tJUMPmin and hJUMPmin]) loads were monitored across a 5-week preseason period in 12 Division 1 (age: 22.5 [3.9] y; stature: 188 [6.2] cm; body mass: 85 [11.6] kg; training experience: 9.4 [4.2] y) and 12 Division 2 (age: 20.7 [2.9] y; stature: 186 [6.2] cm; body mass: 77.8 [9.6] kg; training experience: 5.6 [2.3] y) male volleyball players. Furthermore, differences in load were assessed for each drill typology (warm-up, conditioning, technical, tactical, and integral). Results: No effects (P >.05) of level of competition on the internal (except for summated HR zone, P =.05) and external loads (except for tJUMPmin, P =.002) were found. Differently, drill typologies showed an effect (P <.001) on all the investigated internal- and external-load measures. The main post hoc results revealed higher (P <.05) percentage of peak HR, summated HR zone, PlayerLoad per minute, and tACCmin in warm-up and conditioning drills, while higher (P <.05) hDECmin and hJUMPmin were found in tactical and integral drills. Conclusions: These results suggest that volleyball coaches use warm-up and conditioning drills when aiming at increasing the internal loads, PlayerLoad per minute, and tACCmin, while tactical and integral drills should be preferred to enhance the number of hDECmin and hJUMPmin. [ABSTRACT FROM AUTHOR]

Purpose: The study aimed to conduct a comparative analysis of physical performance indicators and assess the levels of performance monotony and strain experienced by basketball referees. Methods: The study involved the participation of 12 basketball referees (mean age: 40.0 [4.9] y) affiliated with the International Basketball Federation. The investigation was carried out throughout 2 density tournaments, wherein the maximum heart rate, average heart rate, performance monotony, and performance strain were documented for 3 variables. Results: The findings indicated significant variations in the mean heart rate, maximum heart rate, total distance monotony, total distance strain, the total number of sprints monotony, the total number of sprints strain, calories monotony, and calories strain (P <.05). Decreasing the density of elite-level basketball competitions has been observed to reduce the monotony and strain experienced by referees. However, this action does not increase motion distance or speed zones. Conclusions: The environmental stressors experienced by senior-level athletes (World Cup) differ from those encountered by younger athletes (World Cup Under 19). Further investigation is required to ascertain the potential effects of competition monotony and strain on decision-making processes and the overall quality of refereeing. [ABSTRACT FROM AUTHOR]

This study sought to investigate the effect of cold ambient temperature on subcutaneous abdominal adipose tissue (SCAAT) lipolysis and blood flow during steady-state endurance exercise in endurance-trained cyclists. Ten males (age: 23 ± 3 years; peak oxygen consumption: 60.60 ± 4.84 ml·kg−1·min−1; body fat: 18.4% ± 3.5%) participated in baseline lactate threshold (LT) and peak oxygen consumption testing, two familiarization trials, and two experimental trials. Experimental trials consisted of cycling in COLD (3 °C; 42% relative humidity) and neutral (NEU; 19 °C; 39% relative humidity) temperatures. Exercise consisted of 25 min cycling at 70% LT and 25 min at 90% LT. In situ SCAAT lipolysis and blood flow were measured via microdialysis. Heart rate, core temperature, carbohydrate and fat oxidation, blood glucose, and blood lactate were also measured. Heart rate, core temperature, oxygen consumption, and blood lactate increased with exercise but were not different between COLD and NEU. SCAAT blood flow did not change from rest to exercise or between COLD and NEU. Interstitial glycerol increased during exercise (p <.001) with no difference between COLD and NEU. Fat oxidation increased (p <.001) at the onset of exercise and remained elevated thereafter with no difference between COLD and NEU. Carbohydrate oxidation increased with increasing exercise intensity and was greater at 70% LT in COLD compared to NEU (p =.030). No differences were observed between conditions for any other variable. Cycling exercise increased SCAAT lipolysis but not blood flow. Ambient temperature did not alter SCAAT metabolism, SCAAT blood flow, or fat oxidation in well-trained cyclists, though cold exposure increased whole-body carbohydrate oxidation at lower exercise intensities. [ABSTRACT FROM AUTHOR]

Purpose: The study had 3 purposes: (1) to develop an index using machine-learning techniques to predict the fitness status of soccer players, (2) to explore the index's validity and its relationship with a submaximal run test (SMFT), and (3) to analyze the impact of weekly training load on the index and SMFT outcomes. Methods: The study involved 50 players from an Italian professional soccer club. External and internal loads were collected during training sessions. Various machine-learning algorithms were assessed for their ability to predict heart-rate responses during the training drills based on external load data. The fitness index, calculated as the difference between actual and predicted heart rates, was correlated with SMFT outcomes. Results: Random forest regression (mean absolute error = 3.8 [0.05]) outperformed the other machine-learning algorithms (extreme gradient boosting and linear regression). Average speed, minutes from the start of the training session, and the work:rest ratio were identified as the most important features. The fitness index displayed a very large correlation (r =.70) with SMFT outcomes, with the highest result observed during possession games and physical conditioning exercises. The study revealed that heart-rate responses from SMFT and the fitness index could diverge throughout the season, suggesting different aspects of fitness. Conclusions: This study introduces an "invisible monitoring" approach to assess soccer player fitness in the training environment. The developed fitness index, in conjunction with traditional fitness tests, provides a comprehensive understanding of player readiness. This research paves the way for practical applications in soccer, enabling personalized training adjustments and injury prevention. [ABSTRACT FROM AUTHOR]

In articles on the methodology of studies investigating affective and enjoyment responses to high-intensity interval training, we noted that, occasionally, exercise conditions described as involving "high" intensity exhibited heart rates that were only as high as, or even lower than, heart rates recorded during comparator conditions described as being of "moderate" intensity. Drs. Vollaard, Metcalfe, Kinghorn, Jung, and Little suggest instead that exercise intensity in high-intensity interval-training studies can be defined in terms of percentages of peak workload. Although we maintain that defining exercise intensity in terms of percentages of maximal heart rate is a suboptimal way to quantify the degree of homeostatic perturbations in response to exercise, we are unconvinced that definitions of intensity relying solely on workload are appropriate for studies investigating affective and enjoyment responses to exercise. The reason is that affect is theorized to have evolved to relay information about homeostatic perturbations to consciousness. [ABSTRACT FROM AUTHOR]

Purpose: This preliminary study examined the influence of estimated menstrual-cycle (MC) phase on responses to soccer matches and training sessions in preparation for and during the FIFA (Fédération internationale de football association) Women's World Cup 2019. Methods: Twenty outfield players representing a national team were tracked over a 45-day period. External (10-Hz global positioning system; total and distance covered at high-metabolic power [≥20 W·kg−1]) and internal load measures (minutes ≥80% heart-rate maximum, sessional ratings of perceived exertion) were collected during all training and matches, with single-item wellness measures (fatigue, soreness, sleep quality, and sleep duration) collected each morning prior to activity. MC phase was estimated individually via an algorithm, informed from pretournament survey responses and ongoing symptom reporting (FitrWoman). Model comparison statistics were used to determine the impact of estimated MC phase in nonhormonal contraceptive users (n = 16). Results: Sessional rating of perceived exertion responses to total distances ≥5 km were higher during the luteal phase (+0.6–1.0 au; P ≤.0178) versus menstruation (phase 1), but no other observable dose–response trends were observed. Sleep, fatigue, and soreness ratings were not typically associated with MC phase, with the exception of exacerbated fatigue ratings in luteal versus follicular phase 48 hours postmatch (−0.73 au, P =.0275). Conclusions: Preliminary findings suggest that estimated MC phase may contribute to the understanding of the dose–response to soccer training and matches. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate acute psychophysiological responses to repeated-sprint training in hypoxia (RSH) combined with whole-body cryotherapy (WBC). Method: Sixteen trained cyclists performed 3 sessions in randomized order: RSH, WBC-RSH (WBC pre-RSH), and RSH-WBC (WBC post-RSH). RSH consisted of 3 sets of 5 × 10-second sprints with 20-second recovery at a simulated altitude of 3000 m. Power output, muscle oxygenation (tissue saturation index), heart-rate variability, and recovery perception were analyzed. Sleep quality was assessed on the nights following test sessions and compared with a control night using nocturnal ActiGraphy and heart-rate variability. Results: Power output did not differ between the conditions (P =.27), while the decrease in tissue saturation index was reduced for WBC-RSH compared to RSH-WBC in the last set. In both conditions with WBC, the recovery perception was higher compared to RSH (WBC-RSH: +15.4%, and RSH-WBC: +21.9%, P <.05). The number of movements during the RSH-WBC night was significantly lower than for the control night (−18.7%, P <.01) and WBC-RSH (−14.9%, P <.05). RSH led to a higher root mean square of the successive differences of R-R intervals and high-frequency band during the first hour of sleep compared to the control night (P <.05) and RSH-WBC (P <.01). Conclusions: Inclusion of WBC in an RSH session did not modify the power output but could improve prolonged performance in hypoxia by maintaining muscle oxygenation. A single RSH session did not deteriorate sleep quality. WBC, particularly when performed after RSH, positively influenced recovery perception and sleep. [ABSTRACT FROM AUTHOR]

Purpose: Monitoring player readiness to train and perform is an important practical concept in football. Despite an abundance of research in this area in the male game, to date, research is limited in female football. The aims of this study were, first, to summarize the current literature on the monitoring of readiness in female football; second, to summarize the current evidence regarding the monitoring of the menstrual cycle and its potential impact on physical preparation and performance in female footballers; and third, to offer practical recommendations based on the current evidence for practitioners working with female football players. Conclusions: Practitioners should include both objective (eg, heart rate and countermovement jump) and subjective measures (eg, athlete-reported outcome measures) in their monitoring practices. This would allow them to have a better picture of female players' readiness. Practitioners should assess the reliability of their monitoring (objective and subjective) tools before adopting them with their players. The use of athlete-reported outcome measures could play a key role in contexts where technology is not available (eg, in semiprofessional and amateur clubs); however, practitioners need to be aware that many single-item athlete-reported outcome measures instruments have not been properly validated. Finally, tracking the menstrual cycle can identify menstrual dysfunction (eg, infrequent or irregular menstruation) that can indicate a state of low energy availability or an underlying gynecological issue, both of which warrant further investigation by medical practitioners. [ABSTRACT FROM AUTHOR]

Purpose: To investigate performance-determining variables of an on-snow sprint cross-country skiing competition and the evolvement in their relationship with performance as the competition progresses from the individual time trial (TT) to the final. Methods: Sixteen national-level male junior skiers (mean [SD] age, 18.6 [0.8] y; peak oxygen uptake [VO2peak], 67.6 [5.5] mL·min−1·kg−1) performed a simulated sprint competition (1.3 km) in the skating style, comprising a TT followed by 3 finals (quarterfinals, semifinals, and final) completed by all skiers. In addition, submaximal and incremental roller-ski treadmill tests, on-snow maximal speed tests, and strength/power tests were performed. Results: VO2peak and peak treadmill speed during incremental testing and relative heart rate, rating of perceived exertion, blood lactate concentrations, and gross efficiency during submaximal testing were all significantly correlated with performance in the TT and subsequent finals (mean [range] r values:.67 [.53–.86], all P <.05). Relative VO2peak and submaximal relative heart rate and blood lactate concentration were more strongly correlated with performance in the semifinals and final compared with the TT (r values:.74 [.60–.83] vs 0.55 [.51–.60], all P <.05). Maximal speed in uphill and flat terrain was significantly correlated with performance in the TT and subsequent finals (r values:.63 [.38–.70], all P <.05), while strength/power tests did not correlate significantly with sprint performance. Conclusions: VO2peak and high-speed abilities were the most important determinants of sprint cross-country skiing performance, with an increased importance of VO2peak as the competition format progressed toward the final. [ABSTRACT FROM AUTHOR]

Background: Submaximal fitness test (SMFT) outcome measures are frequently collected with a wide array of technologies and methodological approaches. Purpose: To examine the test–retest reliability of various SMFT outcome measures derived from different protocols and analytical techniques. Methods: Twenty-six semiprofessional adult soccer players performed 3 SMFT protocols, including 2 continuous (3 min, 11 and 12.8 km·h−1) and 1 intermittent (4 × 50 m, 18 km·h−1) twice, each separated by 7 days. Heart-rate (HR) indices (exercise HR, HR recovery) and scapula-mounted (PlayerLoad vector magnitude) and foot-mounted (flight time and contact time, stride length) microelectrical mechanical system–derived variables were collected using different time frames and analytical approaches adopted in the literature and practice. Absolute reliability was quantified as the group mean difference, typical error of measurement, also expressed as the coefficient of variation (where appropriate) and standardized units (ie, d). Intraclass correlation coefficient was used to quantify relative reliability. Results: The highest degrees of reliability were evident for exercise HR (typical error: 1.0%–1.6% points), the vertical component of PlayerLoad (expressed in arbitrary units; coefficient of variation: 5.5%–7.0%), and contact time (coefficient of variation: 1.5%–3.0%). These estimates were not influenced by SMFT protocol or analytical approach. All other measures displayed poorer reliability and/or were different between protocols and analytical methods. Conclusions: SMFT protocols impact the test–retest reliability of various outcome measures; however, exercise HR, vertical PlayerLoad, and contact time (derived from foot-mounted micro-electrical mechanical systems) appear to have stable measurement properties to assist the assessment of aerobic capacity and lower-limb neuromuscular status, respectively. [ABSTRACT FROM AUTHOR]

Purpose: To compare the energetic contribution and pacing in 2000- and 1500-m maximal rowing-ergometer performances. Methods: On separate visits (>48 h apart, random order), 18 trained junior (16.7 [0.4] y) male rowers completed 3 trials: a 7 × 4-minute graded exercise test, a 2000-m time trial (TT2000), and a 1500-m TT (TT1500). Respiratory gases were continuously measured throughout each trial. The submaximal power-to-oxygen-consumption relationship from the graded exercise test was used to determine the accumulated oxygen deficit for each TT. Differences in mean power output (MPO), relative anaerobic contribution, percentage of peak oxygen uptake, pacing index, maximum heart rate, rating of perceived exertion, and blood lactate concentration were assessed using linear mixed modeling. Results: Compared to TT2000 (324 [24] W), MPO was 5.2% (3.3%) higher in TT1500 (341 [29 W]; P <.001, η p 2 =.70). There was a 4.9% (3.3%) increase (P <.001, η p 2 =.71) in anaerobic contribution from 17.3% (3.3%) (TT2000) to 22.2% (4.3%) (TT1500). Compared to TT1500, maximum heart rate, rating of perceived exertion, and blood lactate concentration were all greater (P <.05) in TT2000. The pacing index was not different between trials. Percentage increase in MPO from TT2000 to TT1500 was negatively associated with pacing variance in TT1500 (R2 =.269, P =.027). Conclusions: Maximal ergometer performance over 1500 m requires a significantly greater anaerobic contribution compared with 2000 m. Junior male athletes adopt a consistent pacing strategy across both distances. However, those who experienced greater percentage increases in MPO over the shorter test adopted a more even pacing strategy. To prepare for 1500-m performance, greater emphasis should be placed on developing capacity for work in the severe domain and completing race simulations with a more even pacing strategy. [ABSTRACT FROM AUTHOR]

Guarana (GUA) seed extract, containing caffeine (CAF) and additional bioactive compounds, may positively affect mental performance, but evidence regarding exercise is limited. This investigation assessed acute GUA ingestion compared with CAF on endurance performance. Eleven endurance-trained noncyclists and cyclists (V ˙ O 2 peak = 49.7 ± 5.9, 60.4 ± 4.6 ml·kg·min−1) completed a double-blind, crossover experiment after ingesting (a) 100 mg CAF, (b) 500 mg GUA (containing 130 mg CAF), or (c) placebo (P) prior to 60-min fixed cycling workload (FIX) + 15-min time trial. Oxygen uptake, heart rate, respiratory exchange ratio, blood glucose, and lactate were not different (p ≥.052) during FIX. A significant interaction (p =.042) for perceived exertion was observed at 50-min FIX with lower rating (p =.023) for GUA versus CAF but not compared with P. Work accumulated over 15-min time trial was greater (p =.038) for GUA versus P due to higher early (1–11 min) work outputs. Work performance favored (effect size = 0.18; 95% confidence interval [0.003, 0.355], p =.046) GUA (241.4 ± 39.9 kJ) versus P (232.1 ± 46.6 kJ), but CAF (232.3 ± 43.9) was not different from GUA (effect size = 0.19; 95% confidence interval [−0.022, 0.410], p =.079) or P. Postexercise strength loss was not attenuated with GUA (−5.6 ± 8.5%) or CAF (−8.3 ± 9.4%) versus P (−10.3 ± 5.1%). Acute GUA ingestion improved work performance relative to P, but effects were trivial to small and unrelated to altered substrate oxidation or muscular strength. Ergogenicity may involve central mechanisms reducing perceived effort with GUA (containing 130 mg caffeine). Due to issues related to identical matching of dosage, whether GUA confers additional benefits beyond its CAF content cannot be determined at present. [ABSTRACT FROM AUTHOR]

Purpose: Interval-training sets may be applied in a different sequence within a swimming training session. The aim of this study was to investigate the effect of different set sequences on performance and physiological responses in a training session. Methods: Twelve highly trained male swimmers performed 4 sessions in randomized order. Each session included a different combination of 2 training sets: set A–set C, set C–set A, set B–set C, or set C–set B. Set A consisted of 8 × 200 m at speed corresponding to lactate threshold (30-s recovery), set B included 8 × 100 m at maximum aerobic speed (30-s recovery), and set C included 4 × 50-m all-out swimming (2-min recovery). Performance and physiological responses (lactate concentration, pH, base excess, bicarbonate, heart rate, and heart-rate variability) were measured. Results: Performance in each set was similar between sessions irrespective of set sequence. Blood lactate, heart rate, and acid–base responses during set C were similar in all sessions, but blood lactate was higher in sets A and B during C–A and C–B sessions (P =.01). The overall blood lactate and acid–base response was higher in C–A and C–B sessions compared with A–C and B–C sessions, respectively (P =.01). Heart-rate variability in each set, separately as well as the overall session effect, did not differ and was thus independent to the set sequence applied. Conclusions: Training sessions including all-out swimming as a first set increase the magnitude of metabolic responses to the subsequent aerobic-dominated training set. [ABSTRACT FROM AUTHOR]

We aimed to examine exercise intensity among older adults participating from home in remotely delivered EnhanceFitness (Tele-EF). Exercise intensity was assessed through Fitbit-measured heart rate and the Borg 10-point rating of perceived exertion over 1 week of a 16-week exercise program. Outcomes included mean minutes spent at or above the heart rate reserve calculated threshold for moderate intensity and mean rating of perceived exertion. Pearson and Spearman rank correlations were used to examine associations between baseline characteristics with exercise intensity. During the 60-min classes, the 55 participants achieved moderate intensity for a mean of 21.0 min (SD = 13.5) and had a mean rating of perceived exertion of 4.9 (SD = 1.2). There were no significant associations between baseline characteristics and exercise intensity. Older adults can achieve sustained moderate-intensity exercise during Tele-EF supervised classes. Baseline physical function, physical activity, and other health characteristics did not limit ability to exercise at a moderate intensity, though further investigation is warranted. [ABSTRACT FROM AUTHOR]

Purpose: In sprint biathlon, a J-shaped pacing pattern is commonly used. We investigated whether biathletes with a fast-start pacing pattern increase time-trial skiing and shooting performance by pacing more evenly. Methods: Thirty-eight highly trained biathletes (∼21 y, 27 men) performed an individual 7.5 (3 × 2.5 km for women) or 10-km (3 × 3.3 km for men) time trial on roller skis with a self-selected pacing strategy (day 1). Prone (after lap 1) and standing shooting (after lap 2) stages were performed using paper targets. Based on their pacing strategy in the first time trial (ratio between the initial ∼800-m segment pace on lap 1 and average ∼800-m segment pace on laps 1–3), participants were divided into an intervention group with the fastest starting pace (INT, n = 20) or a control group with a more conservative starting pace (CON, n = 18). On day 2, INT was instructed to reduce their starting pace, while CON was instructed to maintain their day 1 strategy. Results: INT increased their overall time-trial performance more than CON from day 1 to day 2 (mean ± 95% CI; 1.5% ± 0.7% vs 0.0% ± 0.9%, P =.02). From day 1 to day 2, INT reduced their starting pace (5.0% ± 1.5%, P <.01), with reduced ratings of perceived exertion during lap 1 (P <.05). For CON, no change was found for starting pace (−0.8% ± 1.2%) or ratings of perceived exertion between days. No differences were found for shooting performance for either group. Conclusion: Highly trained biathletes with a pronounced fast-start pattern improve skiing performance without any change in shooting performance by pacing more evenly. [ABSTRACT FROM AUTHOR]

Background: The global COVID-19 lockdown restricted daily routines due to the psychological fear of infection, which imposed an unknown universal threat on female college students, affecting physiological health and well-being. However, scant information concerning the efficacy of yogic practice on female college students during the stressful COVID-19 pandemic situation is available. Methods: In a randomized controlled trial (n = 74, age = 21.65 [4.05] y), a study was conducted with a well-conceptualized yogic module for 5 days/week for 3 months (40 min daily in the morning) among yogic volunteers. Pre–post analysis of anthropometric, physiological, and biochemical indices in pandemic-stressed female college students was done for the control and yoga groups. Results: After 3 months of yogic practice, significant reduction (P <.05) in heart rate (d = 0.64, meandiff = 5.43), systolic blood pressure (d = 0.59, meandiff = 5.32), cortisol (d = 0.59, meandiff = 6.354), and triglycerides (P <.01, d = 0.45, meandiff = 13.95) was observed. After yogic follow-up significant improvement (P <.01) in high-frequency (d = 0.56, meandiff = −7.3), total power (d = 0.46, meandiff = −1150) and time domain parameters of heart rate variability led to ameliorate the stress index. Superoxide dismutase (P <.01, d = 0.78, meandiff = 0.69), catalase (P <.05, d = 0.48, meandiff = −7.37), glutathione (P <.001, d = 0.83, meandiff = −4.15), high-density lipoprotein (P <.05, d = 0.48, meandiff = −11.07), and dopamine (P <.001, d = 0.97, meandiff = −135.4) values along with inflammatory markers (P <.001) significantly improved among yogic volunteers after regular practice. Conclusions: Our findings suggest that a 3-month well-conceptualized yogic intervention during COVID-19 may be considered as a prophylactic tool to improve female college students' universal psychophysiological health by ameliorating autonomic functions, cardiometabolic risk factors, and immune metabolisms in an economical and environment-friendly manner. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the interference effects of various resistance-training (RT) protocols on rowing ergometer performance. Methods: Fourteen semiprofessional male rowers randomly completed 5 protocols in separate sessions: (1) control—no RT session was performed, (2) upper-body high-fatigue—4 sets to failure during the bench pull exercise, (3) upper-body low-fatigue—4 sets of 6 repetitions during the bench pull exercise, (4) lower-body high-fatigue—4 sets to failure during the leg-press exercise, and (5) lower-body low-fatigue—4 sets of 6 repetitions during the leg-press exercise. All sets were performed against the 12-repetition-maximum load with 2 minutes of interset rest. Following the completion of the protocols, subjects performed an all-out 1000-m rowing ergometer test. Results: Compared with the control condition, rowing ergometer performance was not significantly affected after the low-fatigue RT protocols (upper body: P ≥.487; Δ = 0.0%–0.2%; lower body: P ≥.200; Δ = −0.2%–0.5%), while it significantly declined following high-fatigue RT protocols (upper body: P ≤.001; Δ = 1.0%–2.0%; lower body: P ≤.002; Δ = 2.1%–2.5%). The average heart rate was significantly lower for the control condition compared with all RT protocols (P ≤.043; Δ = 1.0%–1.5%). Conclusions: To minimize interference on rowing performance, coaches should prioritize the level of effort in RT protocols over specific exercises, specifically avoiding high-fatigue protocols that lead to failure before rowing practice. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of menstrual-cycle (MC) phase on measures of recovery status, that is, resting heart rate, perceived sleep quality, and physical and mental readiness to train, among female endurance athletes. Methods: Daily data were recorded during 1 to 4 MCs (ie, duration ≥21 and ≤35 d, ovulatory, luteal phase ≥10 d) of 41 trained-to-elite-level female endurance athletes (mean [SD]: age 27 [8] y, weekly training: 9 [3] h). Resting heart rate was assessed daily using a standardized protocol, while perceived sleep quality and physical and mental readiness to train were assessed using a visual analog scale (1–10). Four MC phases (early follicular phase [EFP], late follicular phase, ovulatory phase, and midluteal phase [MLP]) were determined using the calendar-based counting method and urinary ovulation-prediction test. Data were analyzed using linear mixed-effects models. Results: Resting heart rate was significantly higher in MLP (1.7 beats·min−1, P =.006) compared with EFP without significant differences between the other MC phases. Perceived sleep quality was impaired in MLP compared with late follicular phase (−0.3, P =.035). Physical readiness to train was lower both in ovulatory phase (−0.6, P =.015) and MLP (−0.5, P =.026) compared with EFP. Mental readiness to train did not show any significant differences between MC phases (P >.05). Conclusions: Although significant, the findings had negligible to small effect sizes, indicating that MC phase is likely not the main determinant of changes in measures of recovery status but, rather, one of the many possible stressors. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to examine the effect of a 6-day basketball tournament on the physical demands, perceptual–physiological responses, well-being, and game statistics of elite under-18 (years of age) players. Methods: Physical demands (player load [PL], steps, impacts, and jumps, all normalized by playing time), perceptual–physiological responses (heart rate and rating of perceived exertion), well-being (Hooper index), and game statistics of 12 basketball players were monitored during 6 consecutive games. Linear mixed models and Cohen d effect sizes were used to assess differences among games. Results: Significant changes were found for PL per minute, steps per minute, impacts per minute, peak heart rate, and Hooper index over the tournament. Pairwise comparisons showed that PL per minute was higher in game #1 than in games #4 (P =.011, large), #5 (P <.001, very large), and #6 (P <.001, very large). PL per minute recorded during game #5 was also lower than in games #2 (P =.041, large) and #3 (P =.035, large). The number of steps per minute was higher in game #1 than in all other games (all P <.05, large to very large). Impacts per minute were significantly higher in game #3 than in games #1 (P =.035, large) and #2 (P =.004, large). The only physiological variable that varied significantly was peak heart rate (higher in game #3 than in game #6; P =.025, large). The Hooper index gradually increased throughout the tournament, indicating poorer player well-being as the tournament advanced. Game statistics did not significantly change among games. Conclusions: The average intensities of each game and the players' well-being gradually decreased throughout the tournament. Conversely, physiological responses were mostly unaffected, and game statistics were unaffected. [ABSTRACT FROM AUTHOR]

Several devices (e.g. linear transducers) have been used for predicting resistance training intensity. However, subjective scales, such as rating of perceived exertion (RPE), are proposed as reliable and easier-to-use tools for monitoring intensity during resistance training. Accordingly. different perceptive scales have been presented in previous research for monitoring intensity during resistance training with elastic bands. The aim was to assess the accuracy and reliability of RPE for quantifying the potential maximal repetitions that could be performed at a given RPE (from 2 to 8 of 10) obtained in the first repetition. For this purpose, 13 recreationally active participants Cage: 26.33 [16.52] years, body mass index: 24.97 [5.08] kg/m² were involved in two familiarization and two experimental sessions. In each session, participants randomly performed one set at each intensity of the first repetition from 2/10 to 8/10 until volitional failure in three different exercises (fly, military press, and push-press). An individual grip width of the elastic band was chosen in each set. The number of repetitions and heart rate were assessed. Significance level was set at p < .05. Repetitions decreased when intensity increased (p < .01) and heart rate was higher in the global exercise (i.e., push-press; p < .05), but nonsignificant differences between intensities were reported. The level of experience influenced the number of repetitions performed (p <.05). Intersession reliability was set from good to excellent (range: 0.64-0.91) Therefore, the RPE of the first repetition is a relevant and reliable parameter related to the total number of repetitions performed for each RPE value in trained participants enrolled in elastic bands resistance training. [ABSTRACT FROM AUTHOR]

In humans, sleep is divided into nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. (1) The non-REM sleep consists of 3 stages (N1-N3), with N1 and N2 [...]

Previous observations demonstrate New Zealand blackcurrant (NZBC) extract to alter cardiovascular responses at rest without prior exercise. However, the prolonged effects of NZBC on blood pressure and heart rate variability following exercise are not known. Participants (n15 [five women], age: 31 ± 9 years, maximal oxygen uptake: 44 ± 9 ml·kg−1·min−1) undertook a control condition of 2 hr of lying supine rest. Subsequently, in a double-blind, placebo (PLA)-controlled, randomized crossover design participants completed 1 hr of treadmill exercise at 50% maximal oxygen uptake followed by 2-hr supine rest with blood pressure and heart rate variability measurement following a 7-day intake of NZBC and PLA. With NZBC, there was an increase in average fat oxidation (NZBC: 0.24 ± 0.11 vs. PLA: 0.17 ± 0.11 g/min, p =.005), and larger high-frequency relative power during the exercise (p =.037). In the 2-hr rest period, delta change for systolic pressure was larger with NZBC than PLA (Control vs. NZBC: −5.6 ± 6.4, Control vs. PLA: −3.5 ± 6.0 mmHg, p =.033) but was not different for diastolic or mean arterial pressure. There were no alterations in heart rate variabilities during the 2 hr following the exercise with NZBC. A 7-day intake of NZBC causes a larger postexercise hypotension response in young, physically active men and women following 1 hr of treadmill exercise at 50% maximal oxygen uptake. [ABSTRACT FROM AUTHOR]

Objective: To investigate the association between physical activity accumulated from early (age 22–27 y) to mid (age 40–45 y) adulthood and resting heart rate at age 41–46 years in women. Methods: Data were from 479 participants in the 1973–1978 cohort of the Australian Longitudinal Study on Women's Health. Participants reported physical activity every 3 years from age 22–27 years to 40–45 years. Linear regression models were used to investigate the associations of a cumulative physical activity score (average physical activity across 18 y; up to 7 surveys) and changes in physical activity from age 22–33 years to 34–45 years with resting heart rate at age 41–46 years. Results: Average resting heart rate at age 41–46 years was 75 (SD: 11) beats per minute. An inverse nonlinear dose–response association between cumulative physical activity and resting heart rate was observed. Overall, accumulation of physical activity was associated with lower resting heart rate regardless of the age when physical activity was accumulated. Women in the highest tertile of physical activity at both age 22–33 years and 34–45 years had a resting heart rate, on average, 8 beats per minute lower (95% confidence interval, −11.42 to −4.69) than those consistently in the lowest tertile of physical activity. Conclusion: Accumulating physical activity, irrespective of timing, appears to provide cardiovascular health benefits for women before the transition to menopause. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the long-term effect of body composition, physical activity, and cardiorespiratory fitness (CRF) from puberty on arterial health in late adolescent males. Methods: The cumulative burden of physical activity (measured with accelerometer), CRF (VO2peak0.82), and body composition (body mass index, fat mass, and fat percentage) from puberty to late adolescence (sum of 4 time points from 12 to 18 y) was assessed in 102 males. Additional analysis on the first (T1) and last (T4) time points was performed. Intima-media thickness (IMT), carotid-femoral pulse wave velocity, and augmentation index adjusted to heart rate of 75 beats per minute (bpm) as dependent variables were measured at T4 and analyzed in multivariable regression models adjusted for known risk factors including maturation, blood pressure, and smoking habits. Results: T1 and cumulative body composition measures were independently associated with IMT, while cumulative (β = −0.011, P =.036) and T4 (β = −0.0.031, P =.001) CRF revealed independent associations with IMT. Individuals with moderate to vigorous physical activity >60 minutes per day at T1 showed relationship (β = −1.091, P =.026) with IMT independently of late adolescent physical activity. No significant relationship was present for arterial function. Conclusion: Arterial structure in adolescent males is associated with physical activity at 12 years while relationship with CRF can be seen in late adolescence and cumulatively from puberty to late adolescence. [ABSTRACT FROM AUTHOR]

Acute ketone monoester (KE) supplementation can alter exercise responses, but the performance effect is unclear. The limited and equivocal data to date are likely related to factors including the KE dose, test conditions, and caliber of athletes studied. We tested the hypothesis that mean power output during a 20-min cycling time trial (TT) would be different after KE ingestion compared to a placebo (PL). A sample size of 22 was estimated to provide 80% power to detect an effect size dz of 0.63 at an alpha level of.05 with a two-tailed paired t test. This determination considered 2.0% as the minimal important difference in performance. Twenty-three trained cyclists (N = 23; peak oxygen uptake: 65 ± 12 ml·kg−1 min−1; M ± SD), who were regularly cycling >5 hr/week, completed a familiarization trial followed by two experimental trials. Participants self-selected and replicated their diet and exercise for ∼24 hr before each trial. Participants ingested either 0.35 g/kg body mass of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate KE or a flavor-matched PL 30 min before exercise in a randomized, triple-blind, crossover manner. Exercise involved a 15-min warm-up followed by the 20-min TT on a cycle ergometer. The only feedback provided was time elapsed. Preexercise venous [β-hydroxybutyrate] was higher after KE versus PL (2.0 ± 0.6 vs. 0.2 ± 0.1 mM, p <.0001). Mean TT power output was 2.4% (0.6% to 4.1%; mean [95% confidence interval]) lower after KE versus PL (255 ± 54 vs. 261 ± 54 W, p <.01; dz = 0.60). The mechanistic basis for the impaired TT performance after KE ingestion under the present study conditions remains to be determined. [ABSTRACT FROM AUTHOR]

Background: Soccer match outcomes rely on technical accuracy, intensity of play, and athlete motivation, and these parameters can be developed during sport-specific practice such as during small-sided games (SSGs). Verbal encouragement as a coaching technique improves exercise intensity and athlete enjoyment (indicative of motivation), but the impact on technical performance alongside these critical parameters remains unknown. Purpose: To examine the effects of verbal encouragement on technical performance, exercise intensity, and enjoyment during SSGs. Methods: Sixteen male youth soccer players (mean [SD]; age: 17.2 [0.4] y; height: 176.3 [7.0] cm; body mass: 68.0 [4.1] kg; body fat: 11.9% [2.2%]) completed 4 sessions of 4-per-side SSG without a goalkeeper. Two sessions were conducted as SSGs with verbal encouragement and 2 without verbal encouragement. Each SSG lasted 25 minutes (4 × 4-min work, 3-min passive recovery between bouts) on a 25 × 35-m pitch. Heart rate (HR) was continuously recorded, and rating of perceived exertion was collected after each SSG. Video analysis was used to quantify technical actions during SSG. Enjoyment was assessed after each SSG using the Physical Activity Enjoyment Scale. Results: Paired t tests revealed that SSGs with verbal encouragement induced higher HR (% maximum HR and mean HR), rating of perceived exertion, and Physical Activity Enjoyment Scale score than SSGs without verbal encouragement (all P <.001, all d ≥ 0.92, large). Compared with SSGs without verbal encouragement, SSGs with verbal encouragement resulted in an increased percentage of successful passes (P <.001, d = 0.73, medium) and number of interceptions (P <.001, d = 0.89, large) and fewer lost balls (P <.001, d = 0.68, medium). Conclusions: Coaches should use verbal encouragement during SSGs to improve physical effort, technical performance, and psychological status in soccer players. [ABSTRACT FROM AUTHOR]

Purpose: To identify differences in heart rate (HR) and concentration of blood lactate ([La]) relationships between laboratory- and field-based skate-roller-skiing tests. Methods: Fourteen world-class biathletes (8 women, 6 men) completed a laboratory- and field-based roller-skiing test using the skate technique. The laboratory-based test comprised 5 to 7 submaximal steps at a fixed incline and speed on a roller-skiing treadmill. The field-based test comprised 5 steps on a course where the final hill was designed to mimic the conditions of the laboratory test. HR and [La] were measured for each step. The HR associated with 2 mmol·L−1 (HR@2 mmol) and 4 mmol·L−1 (HR@4 mmol) of [La] was calculated using an interpolation method. A 1-way analysis of variance and Bland–Altman analyses with 95% limits of agreement (LoA) were used to determine if test type influenced HR@2 mmol or HR@4 mmol. A second-order polynomial was fitted to group-level data to highlight the HR–[La] relationships for laboratory- and field-based tests. Results: HR@2 mmol was lower for field tests than for laboratory tests (mean bias: 1.9%HRmax; 95% LoA: −4.5 to +8.3%HRmax; P <.001). HR@4 mmol was also lower for field tests compared to laboratory tests (mean bias: 2.4%HRmax; 95% LoA: −1.2 to +6.0%HRmax; P <.001). On the group level, the lactate threshold occurred at a lower HR during roller skiing in the field compared to the laboratory. Conclusions: The findings from this study confirm that for a given HR, [La] was greater in field- compared with laboratory-based conditions. These results might have implications for how coaches define training-intensity "zones" during skate roller skiing based on laboratory tests. [ABSTRACT FROM AUTHOR]

Purpose: To examine the effects of a high-carbohydrate diet (HCHO), periodized-carbohydrate (CHO) diet (PCHO), and ketogenic low-CHO high-fat diet (LCHF) on training capacity. Methods: Elite male racewalkers completed 3 weeks of periodic training while adhering to their dietary intervention. Twenty-nine data sets were collected from 21 athletes. Each week, 6 mandatory training sessions were completed, with additional sessions performed at the athlete's discretion. Mandatory sessions included an interval session (10 × 1-km efforts on a 6-min cycle), tempo session (14 km with a 450-m elevation gain), 2 long walks (25–40 km), and 2 easy walks (8–12 km) where "sleep-low" and "train-low" dietary strategies were employed for PCHO. Racewalking speed, heart rate, rating of perceived exhaustion, and blood metabolites were collected around key sessions. Results: LCHF covered less total distance than HCHO and PCHO (P <.001); however, no differences in training load between groups were evident (P =.285). During the interval sessions, walking speed was slower in LCHF (P =.001), equating to a 2.8% and 5.6% faster speed in HCHO and PCHO, respectively. LCHF was also 3.2% slower in completing the tempo session than HCHO and PCHO (P =.001). Heart rate was higher (P =.002) and lactate concentrations were lower (P <.001) in LCHF compared to other groups, despite slower walking speeds during the interval session. No between-groups differences in rating of perceived exhaustion were evident (P =.077). Conclusion: Athletes adhering to an LCHF diet showed impaired training capacity relative to their high-CHO-supported counterparts, completing lower training volumes at slower speeds, with higher heart rates. [ABSTRACT FROM AUTHOR]

Thermoregulation is impaired in individuals with a spinal cord lesion (SCI), affecting sweat capacity, heat loss, and core temperature. This can be particularly problematic for athletes with SCI who exercise in hot and humid conditions, like those during the Tokyo 2020 Paralympic Games. Heat acclimation can support optimal preparation for exercise in such challenging environments, but evidence is limited in endurance athletes with SCI. We evaluated whether seven consecutive days of exercise in the heat would result in heat acclimation. Five elite para-cycling athletes with SCI participated (two females, three males, median (Q1-Q3) 35 (31–51) years, four with paraplegia and one with tetraplegia). All tests and training sessions were performed in a heat chamber (30°C and 75% relative humidity). A time-to-exhaustion test was performed on day 1 (pretest) and day 7 (posttest). On days 2–6, athletes trained daily for one hour at 50–60% of individual peak power (PPeak). Comparing pretest and posttest, all athletes increased their body mass loss (p=0.04), sweat rate (p=0.04), and time to exhaustion (p=0.04). Effects varied between athletes for core temperature and heart rate. All athletes appeared to benefit from our heat acclimation protocol, helping to optimize their preparation for the Tokyo 2020 Paralympic Games. [ABSTRACT FROM AUTHOR]

Objective Gastroschisis is the most common congenital abdominal wall defect, with an increasing incidence. It results in extrusion of abdominal contents with associated delayed intestinal motility. Abnormal heart rate characteristics (HRCs) such as decreased variability occur due to the inflammatory response to sepsis in preterm infants. This study aimed to test the hypothesis that infants with gastroschisis have decreased heart rate variability (HRV) after birth and that this physiomarker may predict outcomes. Study Design We analyzed heart rate data from and clinical variables for all infants admitted with gastroschisis from 2009 to 2020. Results Forty-seven infants were admitted during the study period and had available data. Complex gastroschisis infants had reduced HRV after birth. For those with sepsis and necrotizing enterocolitis, abnormal HRCs occurred early in the course of illness. Conclusion Decreased HRV was associated with complex gastroschisis. Infants in this group experienced complications that prolonged time to full enteral feeding and time on total parenteral nutrition. Key Points Infants with gastroschisis can be classified into two subcategories, simple and complex disease. Those with complex disease often require prolonged stays in the neonatal intensive care unit and costly hospitalizations. We hypothesized that infants with complex gastroschisis are more likely to have abnormal HRC due to intestinal inflammation. In this study, we identified associations between abnormal HRV, heart rate characteristicHRC, and the development of gastroschisis complications. Additionally, we described differences in clinical characteristics between infants with complex versus simple gastroschisis. [ABSTRACT FROM AUTHOR]

Background: Off-label intranasal administration of injectable dexmedetomidine has been widely applied in the pediatric sedation setting. However, the development of an improved drug delivery system that is easy to use is needed. We developed a novel dexmedetomidine nasal spray that can be administered directly without dilution or configuration for pediatric pre-anesthetic sedation. This nasal spray has a fixed dose and is stable during storage. To the best of our knowledge, this is the first licensed nasal spray preparation of dexmedetomidine worldwide. Objective: To evaluate the pre-anesthetic sedation efficacy and safety of the novel dexmedetomidine nasal spray in children. Methods: The study was conducted at 11 sites in China between 24 November 2021 and 20 May 2022 and was registered in ClinicalTrials.gov (NCT05111431, first registration date: 20/10/2021). Subjects (n = 159) between 2 and 6 years old who were to undergo elective surgery were randomized to the dexmedetomidine group (n = 107) or the placebo group (n = 52) in a 2:1 ratio. The dosage was 30 µg or 50 µg based on the stratified body weight. The primary outcome measure was the proportion of subjects who achieved the desired child-parent separation and Ramsay scale ≥ 3 within 45 min of administration. Safety was monitored via the assessments of adverse events, blood pressure, heart rate, respiratory rate and blood oxygen saturation. Results: The proportion of subjects achieving desired parental separation and Ramsay scale ≥ 3 within 45 min was significantly higher in the dexmedetomidine group (94.4%) vs the placebo group (32.0%) (P < 0.0001). As compared with placebo, dexmedetomidine treatment led to more subjects achieving Ramsay scale ≥ 3 or UMSS ≥ 2, and shorter time to reach desired parental separation, Ramsay scale ≥ 3 and UMSS ≥ 2 (all P < 0.0001). Adverse events were reported in 90.7% and 84.0% of subjects in the dexmedetomidine and placebo groups, respectively, and all the events were mild or moderate in severity. Conclusions: This novel dexmedetomidine nasal spray presented effective pre-anesthetic sedation in children with a tolerable safety profile. [ABSTRACT FROM AUTHOR]

Background: To analyze the effects of different anesthesia depths on perioperative heart rate variability and hemodynamics in middle-aged and elderly patients undergoing general anesthesia, and to provide a basis for clinical application. Methods: A total of 111 patients with gastric cancer who were treated with epidural anesthesia combined with general anesthesia were selected as the study subjects, and the patients were randomly divided into group A, group B and group C. The bispectral index (BIS) was maintained by adjusting the infusion speed of anesthetics, the BIS of group A was maintained at 50 ~ 59, the BIS of group B was maintained at 40 ~ 49, and the BIS of group C was maintained at 30 ~ 39. The high-frequency power (HFP), low-frequency power (LFP), total power (TP), mean arterial pressure (MAP), heart rate (HR), diastolic blood pressure (DBP), and systolic blood pressure (SBP) were measured before anesthesia induction (T1), immediately after intubation (T2), 3 min after intubation (T3), and 6 min after extubation (T4). The cognitive function of the patients was evaluated before and 48 h after surgery. Results: The HFP, LFP/HFP, TP, HR, DBP and SBP between the three groups at T1 ~ T3 are significantly difference from each other (P < 0.05). There were significant differences in spontaneous breathing recovery time, eye opening time and extubation time among group A, B and C groups, and group B had the lowest spontaneous breathing recovery time, eye opening time and extubation time (P < 0.05). There was no significant difference in the incidence of adverse reactions during anesthesia between the three groups. The cognitive function score of group B was significantly higher than that of group A and group C (P < 0.05). Conclusions: BIS maintenance of 40 ~ 49 has little effect on perioperative heart rate variability and hemodynamics in middle-aged and elderly patients undergoing general anesthesia, which is helpful for postoperative recovery. [ABSTRACT FROM AUTHOR]

ABSTRACT A common feature in cohort studies is when there is a baseline measurement of the continuous follow‐up or outcome variable. Common examples include baseline measurements of physiological characteristics such as blood pressure or heart rate in studies where the outcome is post‐baseline measurement of the same variable. Methods incorporating the propensity score are increasingly being used to estimate the effects of treatments using observational studies. We examined six methods for incorporating the baseline value of the follow‐up variable when using propensity score matching or weighting. These methods differed according to whether the baseline value of the follow‐up variable was included or excluded from the propensity score model, whether subsequent regression adjustment was conducted in the matched or weighted sample to adjust for the baseline value of the follow‐up variable, and whether the analysis estimated the effect of treatment on the follow‐up variable or on the change from baseline. We used Monte Carlo simulations with 750 scenarios. While no analytic method had uniformly superior performance, we provide the following recommendations: first, when using weighting and the ATE is the target estimand, use an augmented inverse probability weighted estimator or include the baseline value of the follow‐up variable in the propensity score model and subsequently adjust for the baseline value of the follow‐up variable in a regression model. Second, when the ATT is the target estimand, regardless of whether using weighting or matching, analyze change from baseline using a propensity score that excludes the baseline value of the follow‐up variable. [ABSTRACT FROM AUTHOR]

This study compared the weekly training load (TL) variation across different measures. Fifty-two runners reported their heart rate and distance ran for each training session during four weeks of training. Heart rate measures were used to calculate the weekly TRaining IMPulse (W-TRIMP), whereas the distance ran was used to calculate the weekly distance covered (W-DIST). At the end of each week, participants reported their weekly perceived TL (W-RPE). W-DIST was analyzed alone and combined with W-RPE and W-TRIMP. The weekly overall TL variation was compared using paired-t tests. Compared to W-DIST, the W-RPE (ES: −0.29), W-DIST combined with W-RPE (ES: −0.40) and W-DIST combined with W-TRIMP (ES: −0.31) presented a significant difference in week-to-week overall TL variation. Our results suggest that running coach and athletes include, at minimum, an RPE-based TL measure combined with W-DIST in their training routines. [ABSTRACT FROM AUTHOR]

Background and Aims The spleen serves as an important relay organ that releases cardioprotective factor(s) upon vagal activation during remote ischaemic conditioning (RIC) in rats and pigs. The translation of these findings to humans was attempted. Methods Remote ischaemic conditioning or electrical auricular tragus stimulation (ATS) were performed in 10 healthy young volunteers, 10 volunteers with splenectomy, and 20 matched controls. Venous blood samples were taken before and after RIC/ATS or placebo, and a plasma dialysate was infused into isolated perfused rat hearts subjected to global ischaemia/reperfusion. Results Neither left nor right RIC or ATS altered heart rate and heart rate variability in the study cohorts. With the plasma dialysate prepared before RIC or ATS, respectively, infarct size (% ventricular mass) in the recipient rat heart was 36 ± 6% (left RIC), 34 ± 3% (right RIC) or 31 ± 5% (left ATS), 35 ± 5% (right ATS), and decreased with the plasma dialysate from healthy volunteers after RIC or ATS to 20 ± 4% (left RIC), 23 ± 6% (right RIC) or to 19 ± 4% (left ATS), 26 ± 9% (right ATS); infarct size was still reduced with plasma dialysate 4 days after ATS and 9 days after RIC. In a subgroup of six healthy volunteers, such infarct size reduction was abrogated by intravenous atropine. Infarct size reduction by RIC or ATS was also abrogated in 10 volunteers with splenectomy, but not in their 20 matched controls. Conclusions In humans, vagal innervation and the spleen as a relay organ are decisive for the cardioprotective signal transduction of RIC and ATS. [ABSTRACT FROM AUTHOR]

Introduction: Inspiratory muscle fatigue has been shown to have effects on the autonomic nervous system and physical condition. This study aimed to evaluate the influence of an inspiratory muscle fatigue protocol on respiratory muscle strength and heart rate variability in healthy youths. Materials and Methods: A randomized controlled clinical trial, employing double-blinding, was conducted with twenty-seven participants aged 18-45 years, non-smokers and engaged in sports activity at least three times a week for a minimum of 1 year. Participants were randomly assigned to three groups: Inspiratory Muscle Fatigue group, Activation group, and Control group. Measurements of heart rate variability, diaphragmatic ultrasound, and maximum inspiratory pressure were taken at two stages: before the intervention and immediately after treatment. Results: In our results with respect to baseline to post-treatment, the inspiratory muscle fatigue group showed lower values in the Sniff contraction velocity variable (10.96 cm/s ± 1.99-8.34 cm/s ± 1.23; p < 0.01) and higher values in the activation group (10.59 cm/s ± 0.89-12.66 cm/s ± 1.15; p < 0.01) with respect to the control group (10.27 cm/s ± 1.48-9.97 cm/s ± 1.42). On the other hand, the inspiratory muscle fatigue group showed higher values in the Low frequency variable (49.37 n.u. ± 13.91 to 69.48 n.u. ± 8.22; p < 0.01) and lower values in the activation group (57.92 n.u. ± 8.37 to 41.59 n.u. ± 11.21; p < 0.01) with respect to the control group (50.83 n.u. ± 17.30 to 52.10 n.u. ± 20.64). Additionally, significant correlations were found between respiratory variables and heart rate variability variables. Conclusion: Acute fatigue of the inspiratory musculature appears to negatively impact heart rate variability and inspiratory muscle strength in healthy youths. [ABSTRACT FROM AUTHOR]

Understanding the evolving nature of coronary hemodynamics is crucial for early disease detection and monitoring progression. We require digital twins that mimic a patient's circulatory system by integrating continuous physiological data and computing hemodynamic patterns over months. Current models match clinical flow measurements but are limited to single heartbeats. To this end, we introduced the longitudinal hemodynamic mapping framework (LHMF), designed to tackle critical challenges: (1) computational intractability of explicit methods; (2) boundary conditions reflecting varying activity states; and (3) accessible computing resources for clinical translation. We show negligible error (0.0002–0.004%) between LHMF and explicit data of 750 heartbeats. We deployed LHMF across traditional and cloud-based platforms, demonstrating high-throughput simulations on heterogeneous systems. Additionally, we established LHMFC, where hemodynamically similar heartbeats are clustered to avoid redundant simulations, accurately reconstructing longitudinal hemodynamic maps (LHMs). This study captured 3D hemodynamics over 4.5 million heartbeats, paving the way for cardiovascular digital twins. [ABSTRACT FROM AUTHOR]

Effective regulation of emotions is essential in coping with everyday stressors. Although cognitive reappraisal and acceptance are both commonly employed to downregulate negative emotions, they differ in many aspects. Their effectiveness in real‐life situations can also be influenced by prior stress or a person's trait preferences for certain emotion regulation (ER) strategies. In the present study, we compared the effectiveness of both ER strategies in a laboratory setting, while focussing on the effect of stress and trait moderators. Ninety‐eight healthy participants aged 18–40 were randomly divided into three groups with instructions to use reappraisal, acceptance, or nothing while viewing distressing pictures from the IAPS database. Half of the participants in each group underwent a laboratory stressor (socially evaluated cold pressor test) 20–30 min before the ER task. The effectiveness of ER was measured subjectively on the visual analog scale, and by measuring heart rate, skin conductance, and pupil responses. The data show that cognitive reappraisal lowered subjectively experienced negative emotion, while acceptance did not. These group differences were however not supported by psychophysiological indicators. Secondly, although the laboratory stressor elicited cortisol stress responses in our participants, we did not find any effect on ER. Furthermore, the data has not supported the moderation effect by trait reappraisal and acceptance. The present findings show that deliberate usage of ER strategies when viewing emotionally charged pictures leads to a decrease in experienced emotion. On the other hand, the effects of stress and trait moderators were not supported, therefore they may be smaller and more variable than expected. [ABSTRACT FROM AUTHOR]

Background: Sympathetic nerve activity (SNA) plays a central role in the pathogenesis of several diseases such as sepsis and chronic kidney disease (CKD). Activation of microglia in the paraventricular nucleus of the hypothalamus (PVN) has been implicated in SNA. The mechanisms responsible for the adverse prognosis observed in sepsis associated with CKD remain to be determined. Therefore, we aimed to clarify the impact of increased SNA resulting from microglial activation on hemodynamics and organ damage in sepsis associated with CKD. Methods and results: In protocol 1, male Sprague–Dawley rats underwent either nephrectomy (Nx) or sham surgery followed by cecal ligation and puncture (CLP) or sham surgery. After CLP, Nx-CLP rats exhibited decreased blood pressure, increased heart rate, elevated serum creatinine and bilirubin levels, and decreased platelet count compared to Nx-Sham rats. Heart rate variability analysis revealed an increased low to high frequency (LF/HF) ratio in Nx-CLP rats, indicating increased SNA. Nx-CLP rats also had higher creatinine and bilirubin levels and lower platelet counts than sham-CLP rats after CLP. In protocol 2, Nx-CLP rats were divided into two subgroups: one received minocycline, an inhibitor of microglial activation, while the other received artificial cerebrospinal fluid (CSF) intracerebroventricularly via an osmotic minipump. The minocycline-treated group (Nx-mino-CLP) showed attenuated hypotensive and increased heart rate responses compared to the CSF-treated group (Nx-CSF-CLP), and the LF/HF ratio was also decreased. Echocardiography showed larger left ventricular dimensions and inferior vena cava in the Nx-mino-CLP group. In addition, creatinine and bilirubin levels were lower and platelet counts were higher in the Nx-mino-CLP group compared to the Nx-CSF-CLP group. Conclusions: In septic rats with concomitant CKD, SNA was significantly enhanced and organ dysfunction was increased. It has been suggested that the mechanism of exacerbated organ dysfunction in these models may involve abnormal systemic hemodynamics, possibly triggered by activation of the central sympathetic nervous system through activation of microglia in the PVN. [ABSTRACT FROM AUTHOR]