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Folding paper is a seemingly simple act that requires planning, bimanual coordination, and manual strength and control to produce specific forces. Although paper folding has been used as an assessment tool and as a way to promote spatial skills, this study represents the first attempt to document when paper folding emerges across early childhood. Seventy-seven children (ages 18 months to 7 years) and an adult reference group (24 college-aged adults) completed three pre-specified folds on a single piece of paper. Dependent variables included whether children attempted each fold and, if so, the accuracy of each fold. Grip strength, pinch strength, and developmental level were examined as potential correlates of paper folding. The results demonstrated that paper folding emerges as early as 27 months of age but becomes more accurate with age. At least 50% of children between 4 and 5.5 years of age completed folds. Additionally, children with more age-appropriate problem-solving skills attempted more folds, independent of age. These findings provide a descriptive framework for the ages at which paper folding emerges and suggest that paper-folding interventions could be implemented at even earlier ages than what previously has been examined. [ABSTRACT FROM AUTHOR]

Purpose: To identify the main training characteristics and competitive demands in women's road cycling. Methods: A systematic search was conducted on 5 databases according to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. The articles had to be primary studies, written after 1990 with a sample of competitive women between the ages of 15 and 50. The Quality Assessment Tool for Quantitative Studies and the Oxford Levels of Evidence scales were used. Results: The search yielded 1713 articles, of which 20 were included. Studies on training and competitive demands (n = 5) found that both external and internal loads are higher in women than in men. Studies on strength and endurance training (n = 5) showed that both velocity-based and heavy-load strength training programs performed at least 2 days per week and including 3 to 4 lower-body exercises improved performance. Altitude-training studies (n = 3) found that "Live High–Train Low" was effective to increase performance during the first 9 days after the training camp. The 7 remaining studies focused on a range of topics. The methodological quality was strong for 12 studies and moderate for 8. In contrast, the level of evidence was high in 7 and low in the other 13. Conclusions: Endurance training and competitive demands in women's road cycling are higher than those of men. Strength training is effective in women when the frequency, intensity, and number of exercises are appropriate, while altitude training should be completed a few days before competing. Further studies are warranted to better define the participants' competitive level, using a methodological design with a higher level of evidence. [ABSTRACT FROM AUTHOR]

Objective: Individual unsupervised home-based exercise programs can enhance muscle strength, physical function, gait, and balance in older adults. However, the effectiveness of such programs may be limited by the lack of supervision. This study aims to verify the effectiveness of individual unsupervised home-based programs, compare the effects of individual unsupervised home-based to supervised programs, and verify the influence of supervision over individual unsupervised home-based programs on the physical function of older adults. Methods: A systematic literature search was performed in four electronic databases, and the trials involved randomized controlled comparing the home-based programs to supervised, control groups, or home-based + supervised evaluating the muscle strength, physical function, gait, and balance in older adults. Results: Eleven studies met the inclusion criteria. The meta-analysis revealed no differences between home-based program versus supervised program in gait, mobility, and balance, revealing a trend of significance to supervised program on strength (standardized mean difference [SMD] = 0.27, p =.05). The analysis revealed effects in mobility (SMD = 0.40, p =.003), balance (SMD = 0.58, p =.0002), and muscle strength (SMD = 0.36, p =.02) favoring home-based program versus control group. Significant effects between home-based program versus home-based + supervised program were observed in balance (SMD = 0.74, p =.002) and muscle strength (SMD = 0.58, p =.01) in favor of home-based + supervised program. Conclusion: Home-based programs effectively improve older adults' physical function compared with control groups. However, supervised programs were more effective for muscle strength. [ABSTRACT FROM AUTHOR]

Clear definition, identification, and reporting of adverse event (AE) monitoring during training interventions are essential for decision making regarding the safety of training and testing in youths. Purpose: To document the extent to which AEs, resulting from intervention studies targeting muscle strengthening training (MST) in youth, are reported by researchers. Methods: Electronic databases (CINAHL, PubMed, SPORTDiscus, and Web of Science) were searched for English peer-reviewed articles published before April 2018. Inclusion criteria were: (1) average age <16 years, (2) use of MST, (3) statement(s) linked to the presence/absence of AEs, and (4) randomized controlled trials or quasi-experimental designs. Risk of reporting bias for AEs followed recommendations by the Cochrane Collaboration group. Results: One hundred and ninety-one full-text articles were screened. One hundred and thirty met all MST criteria, out of which only 44 (33.8%; n = 1278, age = 12.1 [1.1] y) included a statement as to the presence/absence of adverse events. The 86 other studies (66.2%) included no such statement. Of the reporting 44 studies, 18 (40.1%) indicated one or more adverse events. Of the 93 reported adverse events, 55 (59.1%) were linked to training or testing. Conclusions: Most MST studies in youth do not report presence/absence of adverse events, and when reported, adverse events are not well defined. [ABSTRACT FROM AUTHOR]

Background: Approximately a third of US adults meet the physical activity guidelines of engaging in resistance training 2 times per week, yet few studies have examined how to increase participation rates. The present randomized control trial compared a remotely delivered coaching intervention with an education only control group. Methods: Eligible participants completed 2 remotely delivered Zoom-based personal training sessions during a 1-week run-in period. Participants randomized to the intervention group received synchronous weekly behavioral video coaching sessions over Zoom, whereas the control group received no further contact. Days of resistance training completed were assessed at baseline (pre), 4 weeks (post), and 8 weeks (follow-up). Linear mixed models were used to examine group differences at each time point and within-group differences over time. Results: There were significant between-group differences favoring the intervention, at posttest for both the previous week (b = 0.71, SE = 0.23; P =.002) and the previous 4 weeks (b = 2.54, SE = 0.87; P =.003) but not at the follow-up period for either the last week (b = 0.15, SE = 0.23; P =.520) or the last 4 weeks (b = 0.68, SE = 0.88; P =.443). Conclusion: The present study showed that by providing participants with equipment, skill, and in the case of the intervention group, a remote coaching intervention, resistance training participation increased. [ABSTRACT FROM AUTHOR]

The purpose of the present systematic review and meta-analysis was to explore the effects of mental fatigue on upper and lower body strength endurance. Searches for studies were performed in the PubMed/MEDLINE and Web of Science databases. We included studies that compared the effects of a demanding cognitive task (set to induce mental fatigue) with a control condition on strength endurance in dynamic resistance exercise (i.e.. expressed as the number of performed repetitions at a given load). The data reported in the included studies were pooled in a random-effects meta-analysis of standardized mean differences. Seven studies were included in the review. We found that mental fatigue significantly reduced the number of performed repetitions for upper body exercises (standardized mean difference: -0.41; 95% confidence interval [-0.70. -0.12]; p = .006; I² = 0%). Mental fatigue also significantly reduced the number of performed repetitions in the analysis for lower body exercises (standardized mean difference: -0.39; 95% confidence interval [-0.75, -0.04]; p=.03; I²= 0%). Our results showed that performing a demanding cognitive task-which induces mental fatigue-impairs strength endurance performance. Collectively. our findings suggest that exposure to cognitive tasks that may induce mental fatigue should be minimized before strength endurance-based resistance exercise sessions. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effects of variable-resistance complex training (VRCT) versus traditional complex training (TCT) on strength, power, speed, and leg stiffness (Kleg) in rugby league players during a 6-week mesocycle. Methods: Twenty-four rugby league players competing in the British University and Colleges Sport Premier North Division were randomized to VRCT (n = 8), TCT (n = 8), or control (CON; n = 8). Experimental groups completed a 6-week lower-body complex training intervention (2×/wk) that involved alternating high-load resistance exercise with plyometric exercise within the same session. The VRCT group performed resistance exercises at 70% of 1-repetition maximum (1RM) + 0% to 23% of 1RM from band resistance with a 90-second intracontrast rest interval, whereas the TCT group performed resistance exercise at 93% of 1RM with a 4-minute intracontrast rest interval. Back-squat 1RM, countermovement jump peak power, reactive strength index, sprint times, and Kleg were assessed pretraining and posttraining. Results: VRCT and TCT significantly improved 1RM back squat, countermovement jump peak power, and 5-m sprint time (all P <.05). VRCT also improved Kleg, whereas TCT improved 10- and 20-m sprint times (all P <.05). Between groups, both VRCT and TCT improved 1RM back squat compared with CON (both P <.001). Additionally, VRCT improved Kleg compared with CON (right leg: P =.016) and TCT improved 20-m sprint time compared with CON (P =.042). Conclusions: VRCT and TCT can be implemented during the competitive season to improve strength, power, and 5-m sprint time. VRCT may lead to greater improvements in reactive strength index and Kleg, whereas TCT may enhance 10- and 20-m sprint times. [ABSTRACT FROM AUTHOR]

Background: The present study assessed the association between relative handgrip strength (RHGS) and hypertension incidence in healthy adults. Methods: We performed a case-cohort study on 3784 participants from Ravansar Non-Communicable Diseases cohort study. The absolute HGS was measured using a digital dynamometer. Hypertension was defined as systolic/diastolic blood pressure =140/90 mm Hg and/or use of antihypertensive medications. Cox regression analysis was utilized to estimate hazard ratios of incident hypertension events with RHGS. Results: Physical activity was significantly higher in the participants with hypertension compared with nonhypertensive participants (P <.001). High-level physical activity in the subjects with lower, middle, and upper RHGS was 19.6%, 33.1%, and 47.3%, respectively (P <.001). RHGS was significantly higher in individuals with greater skeletal muscle mass (P <.001). The men and women with the upper RHGS, had an 80% (hazard ratio: 0.2; 95% confidence interval, 0.1–0.3) and 70% (hazard ratio: 0.3; 95% confidence interval, 0.1–1.2), were lower risk of hypertension compared with those with the lower RHGS, respectively. This association remains significant after adjustment for confounding factors in men. Conclusion: The study demonstrated that middle and upper levels of RHGS were associated with a lower risk of hypertension incidence. RHGS may be a protective factor for hypertension. We suggested muscle strengthening exercises. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Resistance training (RT) programs promote skeletal muscle hypertrophy through the progressive physiological stress applied to an individual. Currently, the vast majority of studies regarding the hypertrophic response to RT have focused on either sedentary or untrained individuals. This critically appraised topic focuses on the hypertrophic response to high- and low-load RT in resistance-trained men. Clinical Question: In experienced male weightlifters, does high-load RT lead to greater increases in muscle mass than low-load RT? Summary of Key Findings: Six studies met the inclusion criteria, while 4 studies were included in the analysis. Each of the 4 studies showed that low-load RT elicited hypertrophic gains similar to high-load RT when sets were taken to failure. Three of the studies were not volume equated, indicating a dose–response relationship between training volume-load and skeletal muscle hypertrophy. One of the studies was volume equated, indicating that skeletal muscle hypertrophy could be achieved at levels comparable to those observed in high-load protocols as a result of high levels of metabolic stress and the concomitant recruitment of high-threshold motor units that can occur during fatiguing contractions. Clinical Bottom Line: Evidence suggests that low-load training produces hypertrophic gains similar to those observed in high-load RT protocols when sets are taken to failure in resistance-trained men. Strength of Recommendation: There is moderate to strong evidence to suggest that low-load RT elicits hypertrophic gains similar to those observed in high-load RT protocols when sets are taken to failure in resistance-trained men. [ABSTRACT FROM AUTHOR]

Context: Aquatic plyometric training may provide benefits due to reduced joint loading compared with land plyometric training; however, the reduced loading may also limit performance gains. Objective: To systematically review the effect of aquatic plyometric training on strength, performance outcomes, soreness, and adverse events in healthy individuals. Evidence acquisition: Five databases were searched from inception to June 2020. Quality assessment and data extraction were independently completed by 2 investigators. When similar outcome measures were used, standardized mean differences were calculated. Evidence synthesis: A total of 19 randomized controlled trials with 633 participants (mean age, range 14-30 y) were included. Aquatic plyometric training was most commonly performed in waist to chest deep water (12/19 studies), 2 to 3 times per week for 6 to 12 weeks (18/19 studies), with final program foot contacts ranging from 120 to 550. Meta-analyses were not completed due to the clinical and statistical heterogeneity between studies. Compared with land plyometric training, aquatic plyometric training exercises and dosage were replicated (15/16 studies) and showed typically similar performance gains (3/4 knee extensor strength measures, 2/4 leg extensor strength measures, 3/4 knee flexor strength measures, 7/10 vertical jump measures, 3/3 sprint measures). In total, 2 of 3 studies monitoring muscle soreness reported significantly less soreness following training in water compared with on land. Compared with no active training (no exercise control group or passive stretching), most effect sizes demonstrated a mean improvement favoring aquatic plyometric training (23/32 measures). However, these were not significant for the majority of studies measuring isokinetic knee strength, vertical jump, and sprinting. The effect sizes for both studies assessing leg press strength indicated that aquatic plyometric training is significantly more effective than no training. Conclusion: Aquatic plyometric training appears similarly effective to land plyometric exercise for improving strength, jumping, and sprinting and may be indicated when joint impact loading needs to be minimized. However, the low quality of studies limits the strength of the conclusions. [ABSTRACT FROM AUTHOR]

Background: Despite the recognized health benefits, few older women participate in strength-training exercises. Methods: The purpose of this study was to examine factors related to older women's adherence to strength training after participation in the StrongWomen Program, a nationally disseminated community program. Adherence was defined as ≥4 months of twice-weekly strength training. Surveys were sent to 970 program participants from 23 states and to participants' corresponding program leaders. Five-hundred fifty-seven participants responded (57%). Results: Of respondents who completed surveys (527), 79% (415) adhered to strength training; adherers reported a mean of 14.1 ± 9.1 months of strength training. Logistic-regression analysis revealed that exercise adherence was positively associated with age (p = .001), higher lifetime physical activity levels (p = .045), better perceived health (p = .003), leader's sports participation (p = .028), and leader's prior experience leading programs (p = .006). Conclusion: These data lend insight to factors that may be related to exercise adherence among midlife and older women. [ABSTRACT FROM AUTHOR]

This paper is a meta-analysis of the role of nutritional supplements in strength training focusing on the effects of placebo treatments. We address specifically the results from meta-analysis of 334 findings from 37 studies of the effect of nutritional supplements and physical fitness interventions on strength, stamina, and endurance outcomes, controlling for main effects of the group on which the results were obtained (placebo, treatment, control, for pretest or posttest), with covariates for age, gender, randomization, double-blind procedures, study duration, training load, training frequency, and training status. Finding show that there are significant placebo effects accounting for a substantial portion of the effect size typically associated with treatment interventions. In addition to produce the best evaluations of treatment effects, both control and placebo groups should be included in a double-blind research design using participants who are well familiarized with the study procedures [ABSTRACT FROM AUTHOR]

Purpose: During heavily congested schedules, professional soccer players can experience exacerbated fatigue responses, which are thought to contribute to an increased risk of injury. Given that match-induced residual fatigue can last up to 72 hours, many coaches naturally prioritize recovery in the days immediately following match day. While it is intuitive for coaches and training staff to decrease the amount of auxiliary training practices to focus on recovery, prescribing upper-body resistance training on the day after match play has recently emerged as a specific training modality in this context. While these sessions may be implemented to increase training stimulus, there are limited data available regarding the efficacy of such a practice to improve recovery kinetics. Methods: In this narrative review, the authors look at the theoretical implications of performing upper-body resistance training on the day after match play on the status of various physiological and psychological systems, including neuromuscular, metabolic, hormonal, perceptual, and immunological recovery. Results: The available evidence suggests that in most cases this practice, as currently implemented (ie, low volume, low intensity), is unlikely to be complementary (ie, does not accelerate recovery) but is potentially compatible (ie, does not impair recovery). Conclusion: Overall, because the perception of such sessions may be player dependent, their programming requires an individualized approach and should take into account match dynamics (eg, fixture scheduling, playing time, travel). [ABSTRACT FROM AUTHOR]

Purpose: To provide details on the nature and symptomatic profile of training maladaptation in competitive resistance-based athletes to examine whether there are symptoms that may be used as prognostic indicators of overtraining. Identifying prognostic tools to assess for training maladaptation is essential for avoiding severe overtraining conditions. Methods: A Web-based survey was distributed to a cross-sectional convenience sample of competitive athletes involved in sports with a significant resistance-training component. The 46-item anonymous survey was distributed via industry experts and social media from July to August 2019. Results: The final sample included 605 responses (completion rate: 84%). About 71% of the respondents indicated that they had previously experienced an unexplained decrease in performance. Among those, the majority reported a performance decrement lasting 1 wk to 1 mo (43.8%). General feelings of fatigue were the most frequent self-reported symptom of maladaptation. Acute training maladaptation, lasting <1 mo, was also accompanied by symptoms of musculoskeletal aches and pain. In the majority of cases (92.5%), training maladaptation was accompanied by additional nontraining stressors. A greater proportion of the respondents with more severe maladaptation (>4 mo) were training to muscle failure. Conclusion: The results from this study support the multifactorial nature of training maladaptation. The multidimensional nature of fatigue and individual variability in symptomatic responses precludes definitive prognostic symptoms or differential diagnostic factors of functional/nonfunctional overreaching or the overtraining syndrome in resistance exercise. [ABSTRACT FROM AUTHOR]

The authors aimed to compare the effects of creatine (Cr) supplementation combined with resistance training on skeletal muscle mass (SMM), total body water, intracellular water (ICW), and extracellular water (ECW) in resistance-trained men as well as to determine whether the SMM/ICW ratio changes in response to the use of this ergogenic aid. Twenty-seven resistance-trained men received either Cr (n = 14) or placebo (n = 13) over 8 weeks. During the same period, subjects performed two split resistance training routines four times per week. SMM was estimated from appendicular lean soft tissue assessed by dual-energy X-ray absorptiometry. Total body water, ICW, and ECW were determined by spectral bioelectrical impedance. Both groups showed improvements (p <.05) in SMM, total body water, and ICW, with greater values observed for the Cr group compared with placebo. ECW increased similarly in both groups (p <.05). The SMM/ICW ratio did not change in either group (p >.05), whereas the SMM/ECW ratio decreased only in the Cr group (p <.05). A positive correlation was observed (p <.05) between SMM and ICW changes (r =.71). The authors' results suggest that the increase in muscle mass induced by Cr combined with resistance training occurs without alteration of the ratio of ICW to SMM in resistance-trained men. [ABSTRACT FROM AUTHOR]

Purpose: The "11+ Kids" injury-prevention program has been shown to reduce injuries and related costs in youth football players less than 14 y of age. A major argument to convince coaches to use this exercise-based injury-prevention program is a potential performance enhancement of the players. Therefore, this study investigated the effects of the "11 + Kids" program on isokinetic strength. Methods: Two teams were randomly assigned to the intervention and control groups. The intervention group replaced their warm-up by the "11+ Kids" and the control group warmed up as usual. Two days before and after the 10-wk intervention, isokinetic strength of the hip adductors and abductors, knee flexors and extensors, and ankle invertors and evertors was tested. Results: Thirty-one players (mean age 11.5 [0.8] y) completed the study. The intervention group showed large improvements in all isokinetic strength measures (P < .001 for all measures; Cohen d = 0.8-1.4), whereas the control group only showed negligible to medium positive effects (P values ranging from .006 to .718; Cohen d = -0.1 to 0.7). The intervention was beneficial compared with the control group regarding isokinetic strength of the hip adductors (P < .001), knee flexors (P = .002), and ankle evertors (P < .001) and invertors (P = .005). Conclusions: Given the relatively short intervention period of 10 wk, the observed improvements relate to a practically meaningful effect of the intervention. The gain in strength may improve players' performance and may contribute to a reduction of injury risk in the long-term application. [ABSTRACT FROM AUTHOR]

Eccentric-focused training promotes greater gains in muscle strength compared with other types of training in adults. However, for older adults, these findings are still not well understood. A systematic review and meta-analysis were performed using manuscripts that performed eccentric-focused and conventional resistance training for at least 4 weeks and evaluated maximum muscle strength through tests of maximum repetitions in weight machine exercises (knee extension and leg press exercises). Five studies were included (n = 138). Increases in muscle strength were found in both resistance training groups, without a difference between them through meta-analysis. However, a large effect size has been observed only in eccentric-focused training. The findings suggest that resistance training protocols are similar for improving maximal strength in older adults, despite larger effect sizes for eccentric-focused training. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the association between muscle quality index (MQI) and phase angle (PhA) after a program of progressive resistance training (RT) in older women. Sixty-six older women with previous RT experience (68.8 ± 4.6 years, 156.6 ±5.3 cm, 66.0 ± 13.0 kg, and 26.7 ± 4.6 kg/m²) underwent 12 weeks of RT (3 x/week, eight exercises, and 10-15 repetition maximum). Anthropometry, muscular strength (one-repetition maximum tests), and body composition (dual-energy X-ray absorptiometry and spectral bioimpedance) were measured pre- and posttraining. There were observed significant increases for PhA, MQI, muscular strength, muscle mass, and reactance, whereas no significant changes in body fat and resistance were found. A significant correlation was observed between the RT-induced relative changes in PhA and MQI (r = .620). We conclude that improvements in MQI induced by RT are associated with increases in PhA. Therefore, PhA may be a valid tool to track changes in MQI after 12 weeks of RT in older women. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to perform a systematic review with meta-analysis and meta-regressions evaluating the effects of isolated strength training (ST), compared with a control group, on total cholesterol (TC), triglycerides (TG), low-density (LDL), high-density lipoprotein (HDL), C-reactive protein (CRP), and adiponectin of adults. Methods: Embase, PubMed, Cochrane, and Scopus data sources were searched up to May 2017. Clinical trials that compared ST with a control group of adults older than 18 years, which evaluated blood TC, TG, LDL, HDL, CRP, or adiponectin as an outcome were included. Random effect was used and the effect size (ES) was calculated by using the standardized mean difference with a 95% confidence interval. Results: ST promotes a reduction in TC (ES: −0.399; P <.001), TG (ES: −0.204; P =.002), LDL (ES: −0.451; P <.001), and CRP (ES: −0.542; P =.01) levels. In addition, ST is associated to an increase in HDL (ES: 0.363; P <.001) and adiponectin concentrations (ES: 1.105; P =.01). Conclusion: ST promotes decreases in TC, TG, LDL, and CRP levels and increases HDL and adiponectin concentrations. Thus, progressive ST could be a potential therapeutic option for improving abnormalities in lipid and inflammatory outcomes in adults. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to compare the effects of resistance training (RT) performed two versus three times per week on phase angle (a cellular health indicator) in older women. A total of 39 women (69.1 ± 5.5 years) were randomly assigned to perform a RT program two (G2X) or three (G3X) days per week for 12 weeks. The RT was a whole-body program (eight exercises, one set, 10–15 repetitions). Phase angle, resistance, reactance, and total body water were assessed by bioimpedance spectroscopy. Intracellular water, reactance, and phase angle increased significantly in G2X (2.1%, 3.0%, and 5.6%, respectively) and G3X (5.0%, 6.9%, and 10.3%, respectively) from pretraining to posttraining, with no significant difference between groups. Bioimpedance resistance decreased similarly in both groups (G2X = −1.7% vs. G3X = −3.2%). We conclude that a single set RT program with a frequency of 2 days per week may be sufficient to promote an improvement in cellular health in older women. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of whey protein (WP) supplementation on muscular strength, hypertrophy, and muscular quality in older women preconditioned to resistance training (RT). In a randomized, double-blind, and placebo (PLA)-controlled design, 31 older women (67.4 ± 4.0 years, 62.0 ± 6.9 kg, 155.9 ± 5.7 cm, and 25.5 ± 2.4 kg/m2) received either 35 g of WP (n = 15) or 35 g of PLA (n = 16) over a 12-week study period while performing an RT program three times a week. Dietary intake, one-repetition maximum test, and skeletal muscle mass by dual-energy X-ray absorptiometry were assessed before and after the intervention period. Both groups showed significant (p <.05) improvements in skeletal muscle mass and total strength, and the WP group realized greater increases (p <.05) in these measures compared with PLA (skeletal muscle mass: WP = +4.8% vs. PLA = +2.3%; strength: WP = +8.7% vs. PLA = +4.9%). Muscular quality increased (p <.05) in both groups (WP = +2.9% vs. PLA = +1.5%) without statistical differences (p >.05) noted between conditions. We conclude that WP supplementation in combination with RT induces higher increases in both strength and hypertrophy in older women preconditioned to RT. [ABSTRACT FROM AUTHOR]

Regular participation in resistance training is important for older people to maintain their health and independence, yet participation rates are low. The study aimed to identify motivators and barriers to older people participating in resistance training. A systematic review was conducted including quantitative, qualitative, and mixed-method studies. Searches generated 15,920 citations from six databases, with 14 studies (n = 1,937 participants) included. In total, 92 motivators and 24 barriers were identified. Motivators specific to participating in resistance training included preventing deterioration (disability), reducing risk of falls, building (toning) muscles, feeling more alert, and better concentration. Looking too muscular and thinking participation increased the risk of having a heart attack, stroke, or death, despite the minimal likelihood of these occurring, were barriers. The analysis indicates that increasing participation in resistance training among older people should focus on the specific benefits valued by older people and the dissemination of accurate information to counter misperceptions. [ABSTRACT FROM AUTHOR]

Purpose: To understand the mechanisms for the effects of resistance training on functional parameters, and to assess the injury risk of the involved tissues, it is necessary to examine the underlying morphological and structural changes of the respective tissues. Methods: The presented information on physiological adaptations have been deduced from cross-sectional studies comparing youth athletes with controls and children with adults as well as from longitudinal studies examining the effects of resistance training in untrained children and adolescents and in youth athletes. Results: The evidence indicates, that training induced changes in motor performance rely partly on enhanced neuromuscular control, and partly on morphological adaptation of muscles and tendons, such as changes in muscle, muscle fiber and tendon cross-sectional area, muscle composition, and tendon material properties, with the bone also adapting by increasing bone mineral content and cortical area. Conclusion: Although the training induced adaptations of the investigated tissues follows similar principles in children as in adults, the magnitude of the adaptive response appears to be more subtle. As studies investigating physiological adaptation in youth athletes are sparse, more research in this area is warranted to elucidate the specific physiological stimulus-response relationship necessary for effective training programs and injury prevention. [ABSTRACT FROM AUTHOR]

Recent studies have brought new insights into the evaluation of power-force-velocity profiles in both ballistic push-offs (eg, jumps) and sprint movements. These are major physical components of performance in many sports, and the methods the authors developed and validated are based on data that are now rather simple to obtain in field conditions (eg, body mass, jump height, sprint times, or velocity). The promising aspect of these approaches is that they allow for more individualized and accurate evaluation, monitoring, and training practices, the success of which is highly dependent on the correct collection, generation, and interpretation of athletes' mechanical outputs. The authors therefore wanted to provide a practical vade mecum to sports practitioners interested in implementing these power-force-velocity-profiling approaches. After providing a summary of theoretical and practical definitions for the main variables, the authors first detail how vertical profiling can be used to manage ballistic push-off performance, with emphasis on the concept of optimal force-velocity profile and the associated force-velocity imbalance. Furthermore, they discuss these same concepts with regard to horizontal profiling in the management of sprinting performance. These sections are illustrated by typical examples from the authors' practice. Finally, they provide a practical and operational synthesis and outline future challenges that will help further develop these approaches. [ABSTRACT FROM AUTHOR]

Evidence suggests that increasing protein distribution may be desirable to promote muscle protein synthesis (MPS) in combination with resistance exercise. However, there is a threshold above which additional protein consumption has limited benefit for MPS and may promote protein loss due to increased oxidation. This study aimed to measure daily protein intake and protein distribution in a cohort of rugby players. Twenty-five developing elite rugby union athletes (20.5 ± 2.3 years, 100.2 ± 13.3 kg, 184.4 ± 7.4 cm) were assessed at the start and end of a rugby preseason. Using a 7-day food diary the reported daily protein intake was 2.2 ± 0.7 g·kg·day-1 which exceeds daily recommendations. The reported carbohydrate intake was 3.6 ± 1.3 g·kg·day-1 which may reflect a suboptimal intake or dietary underreporting. In general, the rugby athletes were regularly consuming more than 20 g of protein; 3.8 ± 0.9 times per day (68 ± 18% of eating occasions). In addition to documenting current dietary intakes, an excess protein estimation score was calculated to determine how frequently the rugby athletes consumed protein above a known effective dose with a margin of error. 2.0 ± 0.9 eating occasions contained protein in excess of doses (20 g) known to promote MPS. Therefore, it is currently unclear whether the consumption of regular large doses of protein will benefit rugby athletes via increasing protein distribution, or whether high protein intakes may have unintended effects including a reduction in carbohydrate and/or energy intake. [ABSTRACT FROM AUTHOR]

This study compared sit to stand (STS) performance between older adults in a nine-week training program focusing on core stability exercises to enhance balance and postural control (EB) versus standard balance (SB) exercises. Repetitions in 30 s (STSreps) and kinematic performance (vertical and horizontal momentum, and margin of stability) were measured pre and postintervention in 23 older adults with at least one fall risk factor. Although both groups combined improved STSreps (P = .001) and vertical momentum (.008), a significant between-group difference was observed for completers only (MANCOVA of posttest group differences, with pretest scores as covariates; P = .04). EB demonstrated a greater but nonsignificant improvement in vertical momentum (P = .095). In conclusion, core stability training added to SB did not result in STS reps improvement. Compliance may modify these results and future larger sample studies should evaluate the impact of core stability training on STS biomechanics. [ABSTRACT FROM AUTHOR]

CONTEXT: In women's handball, the large numbers of throws and passes make the shoulder region vulnerable to overuse injuries. Repetitive throwing motions generate imbalance between shoulder internal- and external-rotator muscles. It has not yet been established whether sling-based training can improve shoulder external-rotator muscle strength. OBJECTIVE: This study investigated the effectiveness of a 6-wk strengthening program in improving shoulder functional profile in elite female high school handball players. DESIGN: Crossover study. SETTING: National elite handball training center. PARTICIPANTS: 25 elite female high school handball players. INTERVENTIONS: The program, completed twice per week for 6 wk, included sling-based strengthening exercises using a suspension trainer for external rotation with scapular retraction and scapular retraction alone. MAIN OUTCOMES: Maximal shoulder external- and internal-rotation strength, shoulder external- and internal-rotation range of motion (ROM), and maximal throwing velocity were assessed preintervention and postintervention for dominant and nondominant sides. RESULTS: After sling training, external- and internal-rotation strength increased significantly for both sides (P ≤ .001, and P = .004, respectively), with the result that there was no significant change in external- and internal-rotation strength ratios for either the dominant or the nondominant shoulder. No significant differences were observed for external-rotation ROM, while internal-rotation ROM decreased moderately, in particular in the dominant shoulder (P = .005). Maximal throwing velocity remained constant for the dominant arm, whereas a significant increase was found for the nondominant arm (P = .017). CONCLUSIONS: This 6-wk strengthening program was effective in improving shoulder external-rotator muscle strength but resulted in a decrease in the ROM in shoulder internal rotation, while throwing velocity remained stable. Adding a stretching program to this type of sling-based training program might help avoid potential detrimental effects on shoulder ROM [ABSTRACT FROM AUTHOR]

Background: Although several studies have examined associations of perceived benefits and barriers with physical activity, no studies have focused on them corresponding to strength-training recommendations for older adults. This study examined the associations among the perceived health benefits of strength training, perceived barriers to strength straining, and stages of change for strength-training behavior in older Japanese adults. Methods: This cross-sectional survey included a random sample of 1144 adults (60-74 years) from the city of Tokorozawa. Stage of change was the independent variable, with perceived health benefits (eg, strength training can reduce body pain) and perceived barriers (eg, facilities are needed for strength training) as dependent variables. Data were analyzed by analysis of covariance and Bonferroni's multiple comparison. Results: After adjusting for demographic variables, the perceived health-benefit score for precontemplation was significantly lower than for the other four stages. The perceived barrier scores in the precontemplation and contemplation stages were significantly higher than those in the preparation and maintenance stages. Conclusions: These results suggest that information about the health benefits for older adults and about the recommended type of strength training might be useful for the development of strategies to promote strength training among older adults. [ABSTRACT FROM AUTHOR]

Caloric restriction occurs when athletes attempt to reduce body fat or make weight. There is evidence that protein needs increase when athletes restrict calories or have low body fat. Purpose: The aims of this review were to evaluate the effects of dietary protein on body composition in energy-restricted resistance-trained athletes and to provide protein recommendations for these athletes. Methods: Database searches were performed from earliest record to July 2013 using the terms protein, and intake, or diet, and weight, or train, or restrict, or energy, or strength, and athlete. Studies (N = 6) needed to use adult (≥ 18 yrs), energy-restricted, resistance-trained (> 6 months) humans of lower body fat (males ≤ 23% and females ≤ 35%) performing resistance training. Protein intake, fat free mass (FFM) and body fat had to be reported. Results: Body fat percentage decreased (0.5-6.6%) in all study groups (N = 13) and FFM decreased (0.3-2.7kg) in nine of 13. Six groups gained, did not lose, or lost nonsignificant amounts of FFM. Five out of these six groups were among the highest in body fat, lowest in caloric restriction, or underwent novel resistance training stimuli. However, the one group that was not high in body fat that underwent substantial caloric restriction, without novel training stimuli, consumed the highest protein intake out of all the groups in this review (2.5-2.6g/kg). Conclusions: Protein needs for energy-restricted resistance-trained athletes are likely 2.3-3.1g/kg of FFM scaled upwards with severity of caloric restriction and leanness. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the effects of acute aerobic and strength exercises on selected executive functions. A counterbalanced, crossover, randomized trial was performed. Forty-two healthy women were randomly submitted to three different conditions: (1) aerobic exercise, (2) strength exercise, and (3) control condition. Before and after each condition, executive functions were measured by the Stroop Test and the Trail Making Test. Following the aerobic and strength sessions, the time to complete the Stroop "non-color word" and "color word" condition was lower when compared with that of the control session. The performance in the Trail Making Test was unchanged. In conclusion, both acute aerobic and strength exercises improve the executive functions. Nevertheless, this positive effect seems to be task and executive function dependent. [ABSTRACT FROM AUTHOR]

Postural disturbances are one of the first reported symptoms in patients with Multiple Sclerosis (MS). The purpose of this study was to investigate the effect of supervised resistance training on postural control in MS patients. Postural control was assessed using amount of sway variability [Root Mean Square (RMS)] and temporal structure of sway variability [Lyapunov Exponent (LyE)] from 15 MS patients. Posture was evaluated before and after completion of three months of resistance training. There were significant differences between MS patients pretraining and healthy controls for both LyE (p = .000) and RMS (p = .002), but no differences between groups after training. There was a significant decrease in RMS (p = .025) and a significant increase in LyE (p = .049) for MS patients pre- to posttraining. The findings suggested that postural control of MS patients could be affected by a supervised resistance training intervention. [ABSTRACT FROM AUTHOR]

Objective: Describe safety and efficacy of a supervised, low-to-moderate intensity strength training program adopted during pregnancy among women at increased risk for back pain. Methods: 32 women adopted strength training twice per week for 12 weeks. Data on musculoskeletal injuries, symptoms, blood pressure, and the absolute external load used for 5 of 6 exercises were obtained during each session. A submaximal lumbar extension endurance exercise test was performed at weeks 5, 10, and 13. Results: The mean (± SD) exercise session attendance rate was 80.5% (± 11.3%). No musculoskeletal injuries occurred. Potentially adverse symptoms (eg, dizziness) were infrequent (2.1% of sessions). Repeated-measures ANOVA showed large increases in the external load across 12 weeks (all P values < .001) and the percentage increases in external load from weeks 1 to 12 were 36% for leg press, 39% for leg curl, 39% for lat pull down, 41% for lumbar extension and 56% for leg extension. Training was associated with a 14% increase in lumbar endurance. Blood pressure was unchanged following acute exercise sessions and after 12 weeks of exercise training. Conclusion: The adoption of a supervised, low-to-moderate intensity strength training program during pregnancy can be safe and efficacious for pregnant women. [ABSTRACT FROM AUTHOR]

This study examined the effect of aerobic training on leg strength, power, and muscle mass in previously sedentary, healthy older men (70-80 yr). Training consisted of 30-45 min of cycle ergometry at 50-70% maximal oxygen consumption (VO2max), 3 times weekly for 16 wk, then 4 wk detraining, or assignment to a nontraining control group (n = 12 both groups). Training increased leg strength, leg power, upper leg muscle mass, and VO2max above pretraining values (21%, 12%, 4%, and 15%, respectively; p < .05). However, all gains were lost after detraining, except for some gain in VO2max. This suggests that cycle ergometry is sufficient stimulus to improve neuromuscular function in older men, but gains are quickly lost with detraining. For the older population cycle ergometry provides the means to not only increase aerobic fitness but also increase leg strength and power and upper leg muscle mass. However, during periods of inactivity neuromuscular gains are quickly lost. [ABSTRACT FROM AUTHOR]

It is unclear whether strength training (ST) or power training (PT) is the more effective intervention at improving muscle strength and power and physical function in older adults. The authors compared the effects of lower extremity PT with those of ST on muscle strength and power in 45 older adults (74.8 ± 5.7 yr) with self-reported difficulty in common daily activities. Participants were randomized to 1 of 3 treatment groups: PT, ST, or wait-list control. PT and ST trained 3 times/wk for 12 wk using knee-extension (KE) and leg-press (LP) machines at ∼70% of 1-repetition maximum (1RM). For PT, the concentric phase of the KE and LP was completed "as fast as possible," whereas for ST the concentric phase was 2-3 s. Both PT and ST paused briefly at the midpoint of the movement and completed the eccentric phase of the movement in 2-3 s. PT and ST groups showed significant improvements in KE and LP 1RM compared with the control group. Maximum KE and LP power increased approximately twofold in PT compared with ST. At 12 wk, compared with control, maximum KE and LP power were significantly increased for the PT group but not for the ST group. In older adults with compromised function, PT leads to similar increases in strength and larger increases in power than ST. [ABSTRACT FROM AUTHOR]

The current study examined exercise self-efficacy and exercise behavior during and after a strength-training intervention program with older adults. A model with crosslagged and contemporaneous paths was tested with structural equations. Within testing occasions, higher physical resistance was related to greater beliefs in efficacy and control over exercise. At 3 months into the intervention, those who had higher physical resistance were less likely to show subsequent changes in beliefs. Those who had higher self-efficacy and control beliefs at 6 months were more likely to report that they were still exercising at 9 and 12 months after the intervention. Findings indicate that exercise self-efficacy and exercise behavior are associated with one another and that beliefs developed during an intervention are important for maintenance of an exercise regimen. [ABSTRACT FROM AUTHOR]

Objective: To determine the effect of training intensity on the contributions of force and velocity to improvements in peak power (PP) after explosive resistance training in older adults. Methods: 112 healthy older adults (69 ± 6 yr) were randomized to explosive resistance training at 20% (G20), 50% (G50), or 80% (G80) maximal strength (1-repetition maximum) for 8-12 wk (twice weekly, 5 exercises, 3 sets of 8 explosive concentric/slow eccentric repetitions) using pneumatic resistance machines or a nontraining control group (CON). Results: Force at peak power (FPP) increased significantly and similarly among training groups compared with CON. Velocity at peak power (VPP) did not improve significantly and remained similar between all groups. Force contributed significantly more to PP production in G80 and G50 than in CON. The change in PP was independently predicted by changes in fat-free mass in G80 and by changes in both FPP and VPP in G50 and G20. Conclusion: Explosive resistance training in older adults results in the ability to produce higher PP outputs with heavier loads without loss of movement velocity. Moderate- to high-intensity training induced a greater relative contribution of force to PP production in this cohort. [ABSTRACT FROM AUTHOR]