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Many individuals do not participate in resistance exercise, with perceived lack of time being a key barrier. Minimal dose strategies, which generally reduce weekly exercise volumes to less than recommended guidelines, might improve muscle strength with minimal time investment. However, minimal dose strategies and their effects on muscle strength are still unclear. Here our aims are to define and characterize minimal dose resistance exercise strategies and summarize their effects on muscle strength in individuals who are not currently engaged in resistance exercise. The minimal dose strategies overviewed were: "Weekend Warrior," single-set resistance exercise, resistance exercise "snacking," practicing the strength test, and eccentric minimal doses. "Weekend Warrior," which minimizes training frequency, is resistance exercise performed in one weekly session. Single-set resistance exercise, which minimizes set number and session duration, is one set of multiple exercises performed multiple times per week. "Snacks," which minimize exercise number and session duration, are brief bouts (few minutes) of resistance exercise performed once or more daily. Practicing the strength test, which minimizes repetition number and session duration, is one maximal repetition performed in one or more sets, multiple days per week. Eccentric minimal doses, which eliminate or minimize concentric phase muscle actions, are low weekly volumes of submaximal or maximal eccentric-only repetitions. All approaches increase muscle strength, and some approaches improve other outcomes of health and fitness. "Weekend Warrior" and single-set resistance exercise are the approaches most strongly supported by current research, while snacking and eccentric minimal doses are emerging concepts with promising results. Public health programs can promote small volumes of resistance exercise as being better for muscle strength than no resistance exercise at all. [ABSTRACT FROM AUTHOR]

Background: Findings from original research, systematic reviews, and meta-analyses have demonstrated the effectiveness of resistance training (RT) on markers of performance and health. However, the literature is inconsistent with regards to the dosage effects (frequency, intensity, time, type) of RT to maximize training-induced improvements. This is most likely due to moderating factors such as age, sex, and training status. Moreover, individuals with limited time to exercise or who lack motivation to perform RT are interested in the least amount of RT to improve physical fitness. Objectives: The objective of this review was to investigate and identify lower than typically recommended RT dosages (i.e., shorter durations, lower volumes, and intensity activities) that can improve fitness components such as muscle strength and endurance for sedentary individuals or beginners not meeting the minimal recommendation of exercise. Methods: Due to the broad research question involving different RT types, cohorts, and outcome measures (i.e., high heterogeneity), a narrative review was selected instead of a systematic meta-analysis approach. Results: It seems that one weekly RT session is sufficient to induce strength gains in RT beginners with < 3 sets and loads below 50% of one-repetition maximum (1RM). With regards to the number of repetitions, the literature is controversial and some authors report that repetition to failure is key to achieve optimal adaptations, while other authors report similar adaptations with fewer repetitions. Additionally, higher intensity or heavier loads tend to provide superior results. With regards to the RT type, multi-joint exercises induce similar or even larger effects than single-joint exercises. Conclusion: The least amount of RT that can be performed to improve physical fitness for beginners for at least the first 12 weeks is one weekly session at intensities below 50% 1RM, with < 3 sets per multi-joint exercise. [ABSTRACT FROM AUTHOR]

Outcomes following anterior cruciate ligament reconstruction (ACLR) need improving, with poor return-to-sport rates and a high risk of secondary re-injury. There is a need to improve rehabilitation strategies post-ACLR, if we can support enhanced patient outcomes. This paper discusses how to optimise the early-stage rehabilitation process post-ACLR. Early-stage rehabilitation is the vital foundation on which successful rehabilitation post-ACLR can occur. Without high-quality early-stage (and pre-operative) rehabilitation, patients often do not overcome major aspects of dysfunction, which limits knee function and the ability to transition through subsequent stages of rehabilitation optimally. We highlight six main dimensions during the early stage: (1) pain and swelling; (2) knee joint range of motion; (3) arthrogenic muscle inhibition and muscle strength; (4) movement quality/neuromuscular control during activities of daily living (5) psycho-social-cultural and environmental factors and (6) physical fitness preservation. The six do not share equal importance and the extent of time commitment devoted to each will depend on the individual patient. The paper provides recommendations on how to implement these into practice, discussing training planning and programming, and suggests specific screening to monitor work and when the athlete can progress to the next stage (e.g. mid-stage rehabilitation entry criteria). [ABSTRACT FROM AUTHOR]

Background: Resistance exercise training is widely used by general and athletic populations to increase skeletal muscle hypertrophy, power and strength. Endogenous sex hormones influence various bodily functions, including possibly exercise performance, and may influence adaptive changes in response to exercise training. Hormonal contraceptive (HC) use modulates the profile of endogenous sex hormones, and therefore, there is increasing interest in the impact, if any, of HC use on adaptive responses to resistance exercise training. Objective: Our aim is to provide a quantitative synthesis of the effect of HC use on skeletal muscle hypertrophy, power and strength adaptations in response to resistance exercise training. Methods: A systematic review with meta-analysis was conducted on experimental studies which directly compared skeletal muscle hypertrophy, power and strength adaptations following resistance exercise training in hormonal contraceptive users and non-users conducted before July 2023. The search using the online databases PUBMED, SPORTDiscus, Web of Science, Embase and other supplementary search strategies yielded 4669 articles, with 8 articles (54 effects and 325 participants) meeting the inclusion criteria. The methodological quality of the included studies was assessed using the "Tool for the assessment of study quality and reporting in exercise". Results: All included studies investigated the influence of oral contraceptive pills (OCP), with no study including participants using other forms of HC. The articles were analysed using a meta-analytic multilevel maximum likelihood estimator model. The results indicate that OCP use does not have a significant effect on hypertrophy [0.01, 95% confidence interval (CI) [− 0.11, 0.13], t = 0.14, p = 0.90), power (− 0.04, 95% CI [− 0.93, 0.84], t = − 0.29, p = 0.80) or strength (0.10, 95% CI [− 0.08, 0.28], t = 1.48, p = 0.20). Discussion: Based on the present analysis, there is no evidence-based rationale to advocate for or against the use of OCPs in females partaking in resistance exercise training to increase hypertrophy, power and/or strength. Rather, an individualised approach considering an individual's response to OCPs, their reasons for use and menstrual cycle history may be more appropriate. Registration: The review protocol was registered on PROSPERO (ID number and hyperlink: CRD42022365677). [ABSTRACT FROM AUTHOR]

Background: The primary aim of our systematic review and meta-analysis was to investigate the effect of resistance training on academic outcomes in school-aged youth. Methods: We conducted a systematic search of six electronic databases (CINAHL Complete, PsycINFO, SCOPUS, Ovid MEDLINE, SPORTDiscus and EMBASE) with no date restrictions. Studies were eligible if they: (a) included school-aged youth (5–18 years), and (b) examined the effect of resistance training on academic outcomes (i.e., cognitive function, academic achievement, and/or on-task behaviour in the classroom). Risk of bias was assessed using the appropriate Cochrane Risk of Bias Tools, funnel plots and Egger's regression asymmetry tests. A structural equation modelling approach was used to conduct the meta-analysis. Results: Fifty-three studies were included in our systematic review. Participation in resistance training (ten studies with 53 effect sizes) had a small positive effect on the overall cognitive, academic and on-task behaviours in school-aged youth (standardized mean difference (SMD) 0.19, 95% confidence interval (CI) 0.05–0.32). Resistance training was more effective (SMD 0.26, 95% CI 0.10–0.42) than concurrent training, i.e., the combination of resistance training and aerobic training (SMD 0.11, 95% CI − 0.05–0.28). An additional 43 studies (including 211 effect sizes) examined the association between muscular fitness and cognition or academic achievement, also yielding a positive relationship (SMD 0.13, 95% CI 0.10–0.16). Conclusion: This review provides preliminary evidence that resistance training may improve cognitive function, academic performance, and on-task behaviours in school-aged youth. PROSPERO Registration: CRD42020175695. [ABSTRACT FROM AUTHOR]

Background: Augmented feedback is often used during resistance training to enhance acute physical performance and has shown promise as a method of improving chronic physical adaptation. However, there are inconsistencies in the scientific literature regarding the magnitude of the acute and chronic responses to feedback and the optimal method with which it is provided. Objective: This systematic review and meta-analysis aimed to (1) establish the evidence for the effects of feedback on acute resistance training performance and chronic training adaptations; (2) quantify the effects of feedback on acute kinematic outcomes and changes in physical adaptations; and (3) assess the effects of moderating factors on the influence of feedback during resistance training. Methods: Twenty studies were included in this systematic review and meta-analysis. This review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Four databases were searched, and studies were included if they were peer-reviewed investigations, written in English, and involved the provision of feedback during or following dynamic resistance exercise. Furthermore, studies must have evaluated either acute training performance or chronic physical adaptations. Risk of bias was assessed using a modified Downs and Black assessment tool. Multilevel meta-analyses were performed to quantify the effects of feedback on acute and chronic training outcomes. Results: Feedback enhanced acute kinetic and kinematic outputs, muscular endurance, motivation, competitiveness, and perceived effort, while greater improvements in speed, strength, jump performance, and technical competency were reported when feedback was provided chronically. Furthermore, greater frequencies of feedback (e.g., following every repetition) were found to be most beneficial for enhancing acute performance. Results demonstrated that feedback improves acute barbell velocities by approximately 8.4% (g = 0.63, 95% confidence interval [CI] 0.36–0.90). Moderator analysis revealed that both verbal (g = 0.47, 95% CI 0.22–0.71) and visual feedback (g = 1.11, 95% CI 0.61–1.61) were superior to no feedback, but visual feedback was superior to verbal feedback. For chronic outcomes, jump performance might have been positively influenced (g = 0.39, 95% CI − 0.20 to 0.99) and short sprint performance was likely enhanced (g = 0.47, 95% CI 0.10–0.84) to a greater extent when feedback is provided throughout a training cycle. Conclusions: Feedback during resistance training can lead to enhanced acute performance within a training session and greater chronic adaptations. Studies included in our analysis demonstrated a positive influence of feedback, with all outcomes showing superior results than when no feedback is provided. For practitioners, it is recommended that high-frequency, visual feedback is consistently provided to individuals when they complete resistance training, and this may be particularly useful during periods of low motivation or when greater competitiveness is beneficial. Alternatively, researchers must be aware of the ergogenic effects of feedback on acute and chronic responses and ensure that feedback is standardised when investigating resistance training. [ABSTRACT FROM AUTHOR]

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

Eccentric resistance exercise emphasizes active muscle lengthening against resistance. In the past 15 years, researchers and practitioners have expressed considerable interest in accentuated eccentric (i.e., eccentric overload) and eccentric-only resistance exercise as strategies for enhancing performance and preventing and rehabilitating injuries. However, delivery of eccentric resistance exercise has been challenging because of equipment limitations. Previously, we briefly introduced the concept of connected adaptive resistance exercise (CARE)—the integration of software and hardware to provide a resistance that adjusts in real time and in response to the individual's volitional force within and between repetitions. The aim of the current paper is to expand this discussion and explain the potential for CARE technology to improve the delivery of eccentric resistance exercise in various settings. First, we overview existing resistance exercise equipment and highlight its limitations for delivering eccentric resistance exercise. Second, we describe CARE and explain how it can accomplish accentuated eccentric and eccentric-only resistance exercise in a new way. We supplement this discussion with preliminary data collected with CARE technology in laboratory and non-laboratory environments. Finally, we discuss the potential for CARE technology to deliver eccentric resistance exercise for various purposes, e.g., research studies, rehabilitation programs, and home-based or telehealth interventions. Overall, CARE technology appears to permit completion of eccentric resistance exercise feasibly in both laboratory and non-laboratory environments and thus has implications for researchers and practitioners in the fields of sports medicine, physiotherapy, exercise physiology, and strength and conditioning. Nevertheless, formal investigations into the impact of CARE technology on participation in eccentric resistance exercise and clinical outcomes are still required. [ABSTRACT FROM AUTHOR]

Background: Eccentric resistance training is recognised as an effective stimulus for enhancing measures of muscular strength and power in adult populations; however, its value in youth athletes is currently not well understood. Objective: The aim of this systematic review was to critically appraise the effects of eccentric resistance training on measures of physical performance (i.e. muscular strength, jump, sprint and change of direction) in youth athletes 18 years of age and under. Methods: Original journal articles published between 1950 and June 2022 were retrieved from electronic search engines of PubMed, SPORTDiscus and Google Scholar's advanced search option. Full journal articles investigating the acute and chronic effects of eccentric resistance training on measures of physical performance in youth athletes (i.e. a person 18 years of age or under who competes in sport) were included. The methodological quality and bias of each study were assessed prior to data extraction using a modified Downs and Black checklist. Results: The search yielded 749 studies, of which 436 were duplicates. Three-hundred studies were excluded based upon title and abstract review and a further 5 studies were removed following the modified Downs and Black checklist. An additional 14 studies were identified during backward screening. Accordingly, 22 studies were included in our systematic review. The Nordic hamstring exercise and flywheel inertial training were the most frequently used eccentric resistance training methods in youth athletes. Improvements in physical performance following the Nordic hamstring exercise are dependent upon an increase in the breakpoint angle, rather than training volume (sets and repetitions), and are further elevated with the addition of hip extension exercises or high-speed running. A minimum of 3 familiarisation trials is necessary to elicit meaningful adaptations following flywheel inertial training. Furthermore, an emphasis should be placed upon decelerating the rotating flywheel during the final one to two thirds of the eccentric phase, rather than gradually throughout the entire eccentric phase. Conclusions: The findings of this systematic review support the inclusion of eccentric resistance training in youth athletes to improve measures of muscular strength, jump, sprint and change of direction performance. The current eccentric resistance training methods are predominantly limited to the Nordic hamstring exercise and flywheel inertial training; however, the efficacy of accentuated eccentric loading to improve jump performance warrants attention in future investigations. [ABSTRACT FROM AUTHOR]

Background: There has been a rise in the participation, professionalism, and profile of female sports in recent years. Sprinting ability is an important quality for successful athletic performance in many female team sports. However, much of the research to date on improving sprint performance in team sports is derived from studies with male participants. Given the biological differences between the sexes, this may be problematic for practitioners when programming to enhance sprint performance in female team-sport athletes. Therefore, the aims of this systematic review were to investigate (1) the overall effect of lower body strength training on sprint performance, and (2) the effect of specific strength training modalities (i.e., reactive-; maximal-; combined-; special-strength) on sprint performance in female team-sport athletes. Methods: An electronic database search was performed using PubMed, MEDLINE, SPORTDiscus, CINAHL, The Cochrane Library, and SCOPUS to identify relevant articles. A random-effects meta-analysis was performed to establish standardised mean difference with 95% confidence intervals and the magnitude and direction of the effect. Results: Fifteen studies were included in the final analysis. The 15 studies represent a total sample size of 362 participants (intervention n = 190; control n = 172) comprising 17 intervention groups and 15 control groups. The overall effects revealed small improvements in sprint performance in favour of the experimental group over 0–10 m and moderate improvements over sprint distances of 0–20 m and 0–40 m. The magnitude of improvement in sprint performance was influenced by the strength modality (i.e., reactive-, maximal-, combined-, and special-strength) utilised in the intervention. Reactive- and combined-strength training methods had a greater effect than maximal- or special-strength modalities on sprint performance. Conclusion: This systematic review and meta-analysis demonstrated that, when compared with a control group (i.e., technical and tactical training), the different strength training modalities exhibited small to moderate improvements in sprint performance in female team-sport athletes. The results of a moderator analysis demonstrated that youth athletes (< 18 years) yielded a greater improvement in sprint performance compared with adults (≥ 18 years). This analysis also supports the use of a longer programme duration (> 8 weeks) with a higher total number of training sessions (> 12 sessions) to improve overall sprint performance. These results will serve to guide practitioners when programming to enhance sprint performance in female team-sport athletes. [ABSTRACT FROM AUTHOR]

Background: Balance and resistance training applied as single-mode interventions have proven to enhance measures of balance and/or muscular fitness in youth and youth athletes. Less is known on the effectiveness of combined or sequenced balance and resistance training in youth and youth athletes. Objective: The objective of this scoping review was to describe the effects of concurrently performed balance and resistance training (i.e., metastable resistance training) and different sequencing schemes of balance and resistance training on measures of balance and/or muscular fitness in healthy youth and youth athletes. We additionally aimed to identify knowledge gaps in the literature. Methods: According to the principles of a scoping review, we followed a broad research question, identified gaps in the literature, and reported findings on the level of single studies but did not aggregate and meta-analyze outcomes across studies. For this purpose, systematic literature searches were conducted in the electronic databases PubMed (including MEDLINE), Web of Science, and SPORTDiscus from inception until August 2022. We included metastable resistance training and sequenced balance and resistance training studies in healthy youth and youth athletes aged 6–18 years that investigated the training-induced effects on measures of balance (e.g., stork balance test) and muscular fitness (e.g., countermovement jump test) in contrast to active/passive controls. The Physiotherapy Evidence Database (PEDro) scale was used to assess the risk of bias. The Strength of Recommendation Taxonomy (SORT) was applied for the whole scoping review on levels A (high strength of recommendation) to C (low strength of recommendation) and for individual studies on levels 1 (high-quality evidence) to 3 (low-quality evidence). Results: The strength of recommendation for the scoping review was level B based on inconsistent or limited-quality evidence. Eleven randomized controlled trials were eligible to be included in this scoping review and each study was rated as 'limited-quality evidence'. A median PEDro score of 6 was computed across the included studies. Four studies examined the effects of metastable resistance training (e.g., plyometric training on unstable surfaces) on measures of balance and/or muscle fitness in youth athletes. The remaining seven studies investigated the impact of sequenced balance and resistance training (e.g., blocked balance training followed by blocked resistance training) on measures of balance and/or muscle fitness in youth and youth athletes. The duration of the intervention programs ranged from 6 to 10 weeks with 2-weekly to 3-weekly exercise sessions. Participants' age range was 10–18 years (mean 15 years). Ten studies examined young male and female athletes from different sports (i.e., basketball, handball, soccer) and one study physical education students. Metastable resistance training compared with plyometric training performed on stable surfaces showed no extra effect on measures of balance and muscular fitness. Stable plyometric training appears to be even more effective to improve jump performance. Sequenced balance and resistance training in the form of a mesocycle of balance followed by plyometric training seems to be particularly effective to improve measures of balance and muscular fitness in young athletes. This scoping review identified knowledge gaps that may indicate future research avenues: (i) comparative studies should be designed to examine how sex, age, maturity status, and expertise level impact on the adaptive potential following metastable resistance training or sequenced balance and resistance training in youth and youth athletes, (ii) at least one established measure of balance and muscular fitness should always be included in study designs to allow future comparison between studies and to aggregate (meta-analyze) findings across studies and (iii) studies are needed that examine neuromuscular and tendomuscular adaptations following these exercise types as well as dosage effects. Conclusions: According to the results of this scoping review, balance training should be an essential training component for youth that is incorporated with the resistance training exercises or introduced at least a month before resistance and plyometric training within a periodized training program. More research is needed to examine the moderating roles of age, maturity status, and sex. [ABSTRACT FROM AUTHOR]

Background: There is evidence that in older adults the combination of strength training (ST) and endurance training (ET) (i.e., concurrent training [CT]) has similar effects on measures of muscle strength and cardiorespiratory endurance (CRE) compared with single-mode ST or ET, respectively. Therefore, CT seems to be an effective method to target broad aspects of physical fitness in older adults. Objectives: The aim was to examine the effects of CT on measures of physical fitness (i.e., muscle strength, power, balance and CRE) in healthy middle-aged and older adults aged between 50 and 73 years. We also aimed to identify key moderating variables to guide training prescription. Study Design: We conducted a systematic review with meta-analysis of randomized controlled trials. Data Sources: The electronic databases PubMed, Web of Science Core Collection, MEDLINE and Google Scholar were systematically searched until February 2022. Eligibility Criteria for Selecting Studies: We included randomized controlled trials that examined the effects of CT versus passive controls on measures of physical fitness in healthy middle-aged and older adults aged between 50 and 73 years. Results: Fifteen studies were eligible, including a total of 566 participants. CT induced moderate positive effects on muscle strength (standardized mean difference [SMD] = 0.74) and power (SMD = 0.50), with a small effect on CRE (SMD = 0.48). However, no significant effects were detected for balance (p > 0.05). Older adults > 65 years (SMD = 1.04) and females (SMD = 1.05) displayed larger improvements in muscle strength compared with adults ≤ 65 years old (SMD = 0.60) and males (SMD = 0.38), respectively. For CRE, moderate positive effects (SMD = 0.52) were reported in those ≤ 65 years old only, with relatively larger gains in females (SMD = 0.55) compared with males (SMD = 0.45). However, no significant differences between all subgroups were detected. Independent single training factor analysis indicated larger positive effects of 12 weeks (SMD = 0.87 and 0.88) compared with 21 weeks (SMD = 0.47 and 0.29) of CT on muscle strength and power, respectively, while for CRE, 21 weeks of CT resulted in larger gains (SMD = 0.62) than 12 weeks (SMD = 0.40). For CT frequency, three sessions per week produced larger beneficial effects (SMD = 0.91) on muscle strength compared with four sessions (SMD = 0.55), whereas for CRE, moderate positive effects were only noted after four sessions per week (SMD = 0.58). A session duration of > 30–60 min generated larger improvements in muscle strength (SMD = 0.99) and power (SMD = 0.88) compared with > 60–90 min (SMD = 0.40 and 0.29, respectively). However, for CRE, longer session durations (i.e., > 60–90 min) seem to be more effective (SMD = 0.61) than shorter ones (i.e., > 30–60 min) (SMD = 0.34). ET at moderate-to-near maximal intensities produced moderate (SMD = 0.64) and small positive effects (SMD = 0.49) on muscle strength and CRE, respectively, with no effects at low intensity ET (p > 0.05). Finally, intra-session ST before ET produced larger gains in muscle strength (SMD = 1.00) compared with separate sessions (SMD = 0.55), whereas ET and ST carried out separately induced larger improvements in CRE (SMD = 0.58) compared with intra-session ET before ST (SMD = 0.49). Conclusions: CT is an effective method to improve measures of physical fitness (i.e., muscle strength, power, and CRE) in healthy middle-aged and older adults aged between 50 and 73 years, regardless of sex. Results of independent single training factor analysis indicated that the largest effects on muscle strength were observed after 12 weeks of training, > 30–60 min per session, three sessions per week, higher ET intensities and when ST preceded ET within the same session. For CRE, the largest effects were noted after 21 weeks of training, four sessions per week, > 60–90 min per session, higher ET intensities and when ET and ST sessions were performed separately. Regarding muscle power, the largest effects were observed after 12 weeks of training and > 30–60 min per session. [ABSTRACT FROM AUTHOR]

There is an increasing interest in female athletic performance—especially concerning the impact of the female menstrual cycle on training response. Indeed, fluctuations in female sex hormones, estrogen and progesterone, during the menstrual cycle regulate protein metabolism and recovery processes in skeletal muscle and may thus impact exercise training-related outcomes. Studies demonstrate that anaerobic capacity and muscle strength are greatest during the follicular phase of the menstrual cycle, when estrogen levels peak. In addition, studies indicate that resistance training conducted in the follicular phase of the menstrual cycle (follicular phase-based resistance training) may be superior to luteal phase-based training in terms of enhancing muscle strength and mass. This raises the possibility that the physiological capabilities of skeletal muscle to adapt to exercise training are dependent on the menstrual cycle and can be important for female athletes in optimizing their training. In this paper, we critically review the current state of the art concerning the impact of menstrual cycle phase-based resistance training and highlight why follicular phase-based resistance training possibly is superior to luteal phase-based training in enhancing resistance training outcomes. Finally, we identify directions for further research. [ABSTRACT FROM AUTHOR]

Background: Carbohydrate (CHO) ingestion has an ergogenic effect on endurance training performance. Less is known about the effect of acute CHO ingestion on resistance training (RT) performance and equivocal results are reported in the literature. Objective: The current systematic review and meta-analysis sought to determine if and to what degree CHO ingestion influences RT performance. Methods: PubMed, MEDLINE, SportDiscus, Scopus, and CINAHL databases were searched for peer-reviewed articles written in English that used a cross-over design to assess the acute effect of CHO ingestion on RT performance outcomes (e.g., muscle strength, power, and endurance) in healthy human participants compared to a placebo or water-only conditions. The Cochrane Collaboration's risk of bias tool and GRADE approaches were used to assess risk of bias and certainty of evidence, respectively. Random effects meta-analyses were performed for total training session volume and post-exercise blood lactate and glucose. Sub-group meta-analysis and meta-regression were performed for categorical (session and fast durations) and continuous (total number of maximal effort sets, load used, and CHO dose) covariates, respectively. Results: Twenty-one studies met the inclusion criteria (n = 226 participants). Pooled results revealed a significant benefit of CHO ingestion in comparison to a placebo or control for total session training volume (standardised mean difference [SMD] = 0.61). Sub-group analysis revealed a significant benefit of CHO ingestion during sessions longer than 45 min (SMD = 1.02) and after a fast duration of 8 h or longer (SMD = 0.39). Pooled results revealed elevated post-exercise blood lactate (SMD = 0.58) and blood glucose (SMD = 2.36) with CHO ingestion. Meta-regression indicated that the number of maximal effort sets, but not CHO dose or load used, moderates the effect of CHO ingestion on RT performance (beta co-efficient [b] = 0.11). Carbohydrate dose does not moderate post-exercise lactate accumulation nor do maximal effort sets completed, load used, and CHO dose moderate the effect of CHO ingestion on post-exercise blood glucose. Conclusions: Carbohydrate ingestion has an ergogenic effect on RT performance by enhancing volume performance, which is more likely to occur when sessions exceed 45 min and where the fast duration is ≥ 8 h. Further, the effect is moderated by the number of maximal effort sets completed, but not the load used or CHO dose. Post-exercise blood lactate is elevated following CHO ingestion but may come at the expense of an extended time-course of recovery due to the additional training volume performed. Post-exercise blood glucose is elevated when CHO is ingested during RT, but it is presently unclear if it has an impact on RT performance. Protocol Registration: The original protocol was prospectively registered on the Open Science Framework (Project identifier: https://doi.org/10.17605/OSF.IO/HJFBW). [ABSTRACT FROM AUTHOR]

The primary aim of this narrative review was to outline the historical genesis of resistance training strategies that incorporate high-load, low-velocity exercises and low-load, high-velocity exercises in the same training session allowing for different "exercise sequences" to be simultaneously implemented. Discrepancies between scientific works and the terminology used within contemporary sport science publications are identified. Upon review of the literature, we propose "complex training" to be considered an umbrella term with 4 different implementations, generally used to indicate a method in which movement velocity or load is altered between sets and/or exercises within the same session with the aim of improving slow and fast force expression. We propose the following terminology for said implementations: contrast training—exercise sequence with alternating high-load and low-load (higher-velocity) exercises in a set-by-set fashion within the same session (corresponding with 'contrast pairs' and 'intra-contrast rest'); descending training—several sets of high-load (e.g., back squat) exercises completed before the execution of several sets of low-load, higher-velocity (e.g., vertical jump) exercises within the same session; ascending training—several sets of low-load, higher-velocity exercises completed before several sets of high-load exercises within the same session; and French contrast training—subset of contrast training in which a series of exercises are performed in sequence within a single session: heavy compound exercise, plyometric exercise, light-to-moderate load compound exercise that maximises movement speed (i.e., external power), and a plyometric exercise (often assisted). Finally, practical applications and training considerations are presented. [ABSTRACT FROM AUTHOR]

Background: There are some controversial findings regarding the benefits of combining protein supplementation with resistance training in order to optimize adaptations to training in older adults. Objective: The aim of this review was to summarize the evidence from meta-analyses assessing the effects of protein supplementation combined with resistance training on body composition and muscle strength in the older population. Methods: We included systematic reviews with meta-analyses of randomized clinical trials that examined the effects of protein and/or amino acid supplementation associated with resistance training compared with resistance training alone on lean body mass, muscle mass, and muscle strength in older people. The search was performed using the MEDLINE (PubMed), Embase, Cochrane Database of Systematic Reviews, Google Scholar, and OpenGrey databases. Methodological quality was assessed using the Assessing the Methodological Quality of Systematic Reviews 2 checklist, and the quality of evidence was determined using the Grading of Recommendations Assessment, Development and Evaluation system. The pooled effect estimates were computed from the standardized mean difference and the 95% confidence interval achieved by each meta-analysis, using random effects models. Results: Five reviews were included, all of moderate methodological quality. In the analyses, protein supplementation combined with resistance training was associated with greater increases in lean body mass and muscle mass when compared with resistance training alone. However, no differences were observed between the interventions on muscle strength increases. The quality of evidence ranged from moderate to very low. Conclusion: Protein supplementation associated with resistance training induces greater increases in lean body mass compared with resistance training alone. In addition, it is suggested that the use of protein supplementation enhances gains in muscle mass but does not promote greater increases in muscle strength. [ABSTRACT FROM AUTHOR]

Eccentric training as a method to enhance athletic performance is a topic of increasing interest to both practitioners and researchers. However, data regarding the effects of performing the eccentric actions of an exercise at increased velocities are limited. This narrative review aimed to provide greater clarity for eccentric methods and classification with regard to temporal phases of exercises. Between March and April 2021, we used key terms to search the PubMed, SPORTDiscus, and Google Scholar databases within the years 1950–2021. Search terms included 'fast eccentric', 'fast velocity eccentric', 'dynamic eccentric', 'accentuated eccentric loading', and 'isokinetic eccentric', analysing both the acute and the chronic effects of accelerated eccentric training in human participants. Review of the 26 studies that met the inclusion criteria identified that completing eccentric tempos of < 2 s increased subsequent concentric one repetition maximum performance, velocity, and power compared with > 4 s tempos. Tempos of > 4 s duration increased time under tension (TUT), whereas reduced tempos allowed for greater volume to be completed. Greater TUT led to larger accumulation of blood lactate, growth hormone, and testosterone when volume was matched to that of the reduced tempos. Overall, evidence supports eccentric actions of < 2 s duration to improve subsequent concentric performance. There is no clear difference between using eccentric tempos of 2–6 s if the aim is to increase hypertrophic response and strength. Future research should analyse the performance of eccentric actions at greater velocities or reduced time durations to determine more factors such as strength response. Tempo studies should aim to complete the same TUT for protocols to determine measures for hypertrophic response. [ABSTRACT FROM AUTHOR]

Background: Older adults experience considerable muscle and bone loss that are closely interconnected. The efficacy of progressive resistance training programs to concurrently reverse/slow the age-related decline in muscle strength and bone mineral density (BMD) in older adults remains unclear. Objectives: We aimed to quantify concomitant changes in lower-body muscle strength and BMD in older adults following a progressive resistance training program and to determine how these changes are influenced by mode (resistance only vs. combined resistance and weight-bearing exercises), frequency, volume, load, and program length. Methods: MEDLINE/PubMed and Embase databases were searched for articles published in English before 1 June, 2021. Randomized controlled trials reporting changes in leg press or knee extension one repetition maximum and femur/hip or lumbar spine BMD following progressive resistance training in men and/or women ≥ 65 years of age were included. A random-effects meta-analysis and meta-regression determined the effects of resistance training and the individual training characteristics on the percent change (∆%) in muscle strength (standardized mean difference) and BMD (mean difference). The quality of the evidence was assessed using the Cochrane risk-of-bias tool (version 2.0) and Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria. Results: Seven hundred and eighty studies were identified and 14 were included. Progressive resistance training increased muscle strength (∆ standardized mean difference = 1.1%; 95% confidence interval 0.73, 1.47; p ≤ 0.001) and femur/hip BMD (∆ mean difference = 2.77%; 95% confidence interval 0.44, 5.10; p = 0.02), but not BMD of the lumbar spine (∆ mean difference = 1.60%; 95% confidence interval − 1.44, 4.63; p = 0.30). The certainty for improvement was greater for muscle strength compared with BMD, evidenced by less heterogeneity (I2 = 78.1% vs 98.6%) and a higher overall quality of evidence. No training characteristic significantly affected both outcomes (p > 0.05), although concomitant increases in strength and BMD were favored by higher training frequencies, increases in strength were favored by resistance only and higher volumes, and increases in BMD were favored by combined resistance plus weight-bearing exercises, lower volumes, and higher loads. Conclusions: Progressive resistance training programs concomitantly increase lower-limb muscle strength and femur/hip bone mineral density in older adults, with greater certainty for strength improvement. Thus, to maximize the efficacy of progressive resistance training programs to concurrently prevent muscle and bone loss in older adults, it is recommended to incorporate training characteristics more likely to improve BMD. [ABSTRACT FROM AUTHOR]

Background: Weightlifting training (WLT) is commonly used to improve strength, power and speed in athletes. However, to date, WLT studies have either not compared training effects against those of other training methods, or been limited by small sample sizes, which are issues that can be resolved by pooling studies in a meta-analysis. Therefore, the objective of this systematic review with meta-analysis was to evaluate the effects of WLT compared with traditional resistance training (TRT), plyometric training (PLYO) and/or control (CON) on strength, power and speed. Methods: The systematic review included peer-reviewed articles that employed a WLT intervention, a comparison group (i.e. TRT, PLYO, CON), and a measure of strength, power and/or speed. Means and standard deviations of outcomes were converted to Hedges' g effect sizes using an inverse variance random-effects model to generate a weighted mean effect size (ES). Results: Sixteen studies were included in the analysis, comprising 427 participants. Data indicated that when compared with TRT, WLT resulted in greater improvements in weightlifting load lifted (4 studies, p = 0.02, g = 1.35; 95% CI 0.20–2.51) and countermovement jump (CMJ) height (9 studies, p = 0.00, g = 0.95; 95% CI 0.04–1.87). There was also a large effect in terms of linear sprint speed (4 studies, p = 0.13, g = 1.04; 95% CI − 0.03 to 2.39) and change of direction speed (CODS) (2 studies, p = 0.36, g = 1.21; 95% CI − 1.41 to 3.83); however, this was not significant. Interpretation of these findings should acknowledge the high heterogeneity across the included studies and potential risk of bias. WLT and PLYO resulted in similar improvements in speed, power and strength as demonstrated by negligible to moderate, non-significant effects in favour of WLT for improvements in linear sprint speed (4 studies, p = 0.35, g = 0.20; 95% CI − 0.23 to 0.63), CODS (3 studies, p = 0.52, g = 0.17; 95% CI − 0.35 to 0.68), CMJ (6 studies, p = 0.09, g = 0.31; 95% CI − 0.05 to 0.67), squat jump performance (5 studies, p = 0.08, g = 0.34; 95% CI − 0.04 to 0.73) and strength (4 studies, p = 0.20, g = 0.69; 95% CI − 0.37 to 1.75). Conclusion: Overall, these findings support the notion that if the training goal is to improve strength, power and speed, supplementary weightlifting training may be advantageous for athletic development. Whilst WLT and PLYO may result in similar improvements, WLT can elicit additional benefits above that of TRT, resulting in greater improvements in weightlifting and jumping performance. [ABSTRACT FROM AUTHOR]

Background: In resistance training, periodization is often used in an attempt to promote development of strength and muscle hypertrophy. However, it remains unclear how resistance training variables are most effectively periodized to maximize gains in strength and muscle hypertrophy. Objective: The aims of this study were to examine the current body of literature to determine whether there is an effect of periodization of training volume and intensity on maximal strength and muscle hypertrophy, and, if so, to determine how these variables are more effectively periodized to promote increases in strength and muscle hypertrophy, when volume is equated between conditions from pre to post intervention. Methods: Systematic searches were conducted in PubMed, Scopus and SPORTDiscus databases. Data from the individual studies were extracted and coded. Meta-analyses using the inverse-variance random effects model were performed to compare 1-repetition maximum (1RM) and muscle hypertrophy outcomes in (a) non-periodized (NP) versus periodized training and (b) in linear periodization (LP) versus undulating periodization (UP). Subgroup analyses examining whether results were affected by training status were performed. Meta-analyses of other periodization model comparisons were not performed, due to a low number of studies. Results: Thirty-five studies met the inclusion criteria. Results of the meta-analyses comparing NP and periodized training demonstrated an overall effect on 1RM strength favoring periodized training (ES 0.31, 95% confidence interval (CI) [0.04, 0.57]; Z = 2.28, P = 0.02). In contrast, muscle hypertrophy did not differ between NP and periodized training (ES 0.13, 95% CI [–0.10, 0.36]; Z = 1.10, P = 0.27). Results of the meta-analyses comparing LP and UP indicated an overall effect on 1RM favoring UP (ES 0.31, 95% CI [0.02, 0.61]; Z = 2.06, P = 0.04). Subgroup analyses indicated an effect on 1RM favoring UP in trained participants (ES 0.61, 95% CI [0.00, 1.22]; Z = 1.97 (P = 0.05)), whereas changes in 1RM did not differ between LP and UP in untrained participants (ES 0.06, 95% CI [–0.20, 0.31]; Z = 0.43 (P = 0.67)). The meta-analyses showed that muscle hypertrophy did not differ between LP and UP (ES 0.05, 95% CI [–0.20, 0.29]; Z = 0.36 (P = 0.72)). Conclusion: The results suggest that when volume is equated between conditions, periodized resistance training has a greater effect on 1RM strength compared to NP resistance training. Also, UP resulted in greater increases in 1RM compared to LP. However, subgroup analyses revealed that this was only the case for trained and not previously untrained individuals, indicating that trained individuals benefit from daily or weekly undulations in volume and intensity, when the aim is maximal strength. Periodization of volume and intensity does not seem to affect muscle hypertrophy in volume-equated pre-post designs. Based on this, we propose that the effects of periodization on maximal strength may instead be related to the neurophysiological adaptations accompanying resistance training. [ABSTRACT FROM AUTHOR]

The body of literature on tendinopathy management has come a long way in the last few decades and a variety of changes in the clinical approach have emerged from this research. One particular approach that shows promise has been called "heavy slow resistance" (HSR), and this has been the subject of investigation in a number of randomized controlled trials. While the premise for this approach is defensible, a critical examination of the implementation of these HSR protocols results in some concerns when compared to basic exercise science principles. This article lays out some considerations that will help future investigators to improve their exercise prescription approaches in this area. [ABSTRACT FROM AUTHOR]

Background: Engaging in both resistance and endurance exercise within the same training program, termed 'concurrent exercise training,' is common practice in many athletic disciplines that require a combination of strength and endurance and is recommended by a number of organizations to improve muscular and cardiovascular health and reduce the risk of chronic metabolic disease. Dietary protein ingestion supports skeletal muscle remodeling after exercise by stimulating the synthesis of muscle proteins and can optimize resistance exercise-training mediated increases in skeletal muscle size and strength; however, the effects of protein supplementation on acute and longer-term adaptive responses to concurrent resistance and endurance exercise are unclear. Objectives: The purpose of this systematic review is to evaluate the effects of dietary protein supplementation on acute changes in muscle protein synthesis and longer-term changes in muscle mass, strength, and aerobic capacity in responses to concurrent resistance and endurance exercise in healthy adults. Methods: A systematic search was conducted in five databases: Scopus, Embase, Medline, PubMed, and Web of Science. Acute and longer-term controlled trials involving concurrent exercise and protein supplementation in healthy adults (ages 18–65 years) were included in this systematic review. Main outcomes of interest were changes in skeletal muscle protein synthesis rates, muscle mass, muscle strength, and whole-body aerobic capacity (i.e., maximal/peak aerobic capacity [VO2max/peak]). The quality of studies was assessed using the National Institute of Health Quality Assessment for Controlled Intervention Studies. Results: Four acute studies including 84 trained young males and ten longer-term studies including 167 trained and 391 untrained participants fulfilled the eligibility criteria. All included acute studies demonstrated that protein ingestion enhanced myofibrillar protein synthesis rates, but not mitochondrial protein synthesis rates during post-exercise recovery after an acute bout of concurrent exercise. Of the included longer-term training studies, five out of nine reported that protein supplementation enhanced concurrent training-mediated increases in muscle mass, while five out of nine studies reported that protein supplementation enhanced concurrent training-mediated increases in muscle strength and/or power. In terms of aerobic adaptations, all six included studies reported no effect of protein supplementation on concurrent training-mediated increases in VO2max/peak. Conclusion: Protein ingestion after an acute bout of concurrent exercise further increases myofibrillar, but not mitochondrial, protein synthesis rates during post-exercise recovery. There is some evidence that protein supplementation during longer-term training further enhances concurrent training-mediated increases in skeletal muscle mass and strength/power, but not whole-body aerobic capacity (i.e., VO2max/peak). [ABSTRACT FROM AUTHOR]

Resistance training (RT) is the only non-pharmacological intervention known to consistently improve, and therefore offset age-related declines in, skeletal muscle mass, strength, and power. RT is also associated with various health benefits that are underappreciated compared with the perceived benefits of aerobic-based exercise. For example, RT participation is associated with reduced all-cause and cancer-related mortality and reduced incidence of cardiovascular disease, hypertension, and symptoms of both anxiety and depression. Despite these benefits, participation in RT remains low, likely due to numerous factors including time constraints, a high-perceived difficulty, and limited access to facilities and equipment. Identification of RT strategies that limit barriers to participation may increase engagement in RT and subsequently improve population health outcomes. Across the lifespan, declines in strength and power occur up to eight times faster than the loss of muscle mass, and are more strongly associated with functional impairments and risks of morbidity and mortality. Strategies to maximise healthspan should therefore arguably focus more on improving or maintaining muscle strength and power than on increasing muscle mass per se. Accumulating evidence suggests that minimal doses of RT, characterised by lower session volumes than in traditional RT guidelines, together with either (1) higher training intensities/loads performed at lower frequencies (i.e. low-volume, high-load RT) or (2) lower training intensities/loads performed at higher frequencies and with minimal-to-no equipment (i.e. resistance 'exercise snacking'), can improve strength and functional ability in younger and older adults. Such minimal-dose approaches to RT have the potential to minimise various barriers to participation, and may have positive implications for the feasibility and scalability of RT. In addition, brief but frequent minimal-dose RT approaches (i.e. resistance 'exercise snacking') may provide additional benefits for interrupting sedentary behaviour patterns associated with increased cardiometabolic risk. Compared to traditional approaches, minimal-dose RT may also limit negative affective responses, such as increased discomfort and lowered enjoyment, both of which are associated with higher training volumes and may negatively influence exercise adherence. A number of practical factors, including the selection of exercises that target major muscle groups and challenge both balance and the stabilising musculature, may influence the effectiveness of minimal-dose RT on outcomes such as improved independence and quality-of-life in older adults. This narrative review aims to summarise the evidence for minimal-dose RT as a strategy for preserving muscle strength and functional ability across the lifespan, and to discuss practical models and considerations for the application of minimal-dose RT approaches. [ABSTRACT FROM AUTHOR]

Background: Both athletes and recreational exercisers often perform relatively high volumes of aerobic and strength training simultaneously. However, the compatibility of these two distinct training modes remains unclear. Objective: This systematic review assessed the compatibility of concurrent aerobic and strength training compared with strength training alone, in terms of adaptations in muscle function (maximal and explosive strength) and muscle mass. Subgroup analyses were conducted to examine the influence of training modality, training type, exercise order, training frequency, age, and training status. Methods: A systematic literature search was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed/MEDLINE, ISI Web of Science, Embase, CINAHL, SPORTDiscus, and Scopus were systematically searched (12 August 2020, updated on 15 March 2021). Eligibility criteria were as follows. Population: healthy adults of any sex and age; Intervention: supervised concurrent aerobic and strength training for at least 4 weeks; Comparison: identical strength training prescription, with no aerobic training; Outcome: maximal strength, explosive strength, and muscle hypertrophy. Results: A total of 43 studies were included. The estimated standardised mean differences (SMD) based on the random-effects model were − 0.06 (95% confidence interval [CI] − 0.20 to 0.09; p = 0.446), − 0.28 (95% CI − 0.48 to − 0.08; p = 0.007), and − 0.01 (95% CI − 0.16 to 0.18; p = 0.919) for maximal strength, explosive strength, and muscle hypertrophy, respectively. Attenuation of explosive strength was more pronounced when concurrent training was performed within the same session (p = 0.043) than when sessions were separated by at least 3 h (p > 0.05). No significant effects were found for the other moderators, i.e. type of aerobic training (cycling vs. running), frequency of concurrent training (> 5 vs. < 5 weekly sessions), training status (untrained vs. active), and mean age (< 40 vs. > 40 years). Conclusion: Concurrent aerobic and strength training does not compromise muscle hypertrophy and maximal strength development. However, explosive strength gains may be attenuated, especially when aerobic and strength training are performed in the same session. These results appeared to be independent of the type of aerobic training, frequency of concurrent training, training status, and age. PROSPERO: CRD42020203777. [ABSTRACT FROM AUTHOR]

Due to improvements in acute burn care over the last few decades, most patients with severe burns (up to 90% of the total body surface) survive. However, the metabolic and cardiovascular complications that accompany a severe burn can persist for up to 3 years post injury. Accordingly, there is now a greater appreciation of the need for strategies that can hasten recovery and reduce long-term morbidity post burn. Rehabilitation exercise training (RET) is a proven effective treatment to restore lean body mass, glucose and protein metabolism, cardiorespiratory fitness, and muscle strength in burn survivors. Despite this, very few hospitals incorporate RET in programs to aid the rehabilitation of patients with severe burns. Given that RET is a safe and efficacious treatment that restores function and reduces post-burn morbidity, we propose that a long-term exercise prescription plan should be considered for all patients with severe burns. In this literature review, we discuss the current understanding of burn trauma on major organ systems, and the positive benefits of incorporating RET as a part of the long-term rehabilitation of severely burned individuals. We also provide burn-specific exercise prescription guidelines for clinical exercise physiologists. [ABSTRACT FROM AUTHOR]

Background: If interplanetary travel is to be successful over the coming decades, it is essential that countermeasures to minimize deterioration of the musculoskeletal system are as effective as possible, given the increased duration of spaceflight associated with such missions. The aim of this review, therefore, is to determine the magnitude of deconditioning of the musculoskeletal system during prolonged spaceflight and recommend possible methods to enhance the existing countermeasures. Methods: A literature search was conducted using PubMed, Ovid and Scopus databases. 5541 studies were identified prior to the removal of duplicates and the application of the following inclusion criteria: (1) group means and standard deviations for pre- and post-spaceflight for measures of strength, muscle mass or bone density were reported (or provided by the corresponding author when requested via e-mail), (2) exercise-based countermeasures were included, (3) the population of the studies were human, (4) muscle function was assessed and (5) spaceflight rather than simulated spaceflight was used. The methodological quality of the included studies was evaluated using a modified Physiotherapy Evidence Database (PEDro) scale for quality, with publication bias assessed using a failsafe N (Rosenthal method), and consistency of studies analysed using I2 as a test of heterogeneity. Secondary analysis of studies included Hedges' g effect sizes, and between-study differences were estimated using a random-effects model. Results: A total of 11 studies were included in the meta-analyses. Heterogeneity of the completed meta-analyses was conducted revealing homogeneity for bone mineral density (BMD) and spinal muscle size (Tau2 < 0.001; I2 = 0.00%, p > 0.05), although a high level of heterogeneity was noted for lower body force production (Tau2 = 1.546; I2 = 76.03%, p < 0.001) and lower body muscle mass (Tau2 = 1.386; I2 = 74.38%, p < 0.001). The estimated variance (≤ -0.306) for each of the meta-analyses was significant (p ≤ 0.033), for BMD (− 0.48 to − 0.53, p < 0.001), lower body force production (− 1.75, p < 0.001) and lower body muscle size (− 1.98, p < 0.001). Spaceflight results in small reductions in BMD of the femur (Hedges g = − 0.49 [− 0.69 to – 0.28]), trochanter (Hedges g = − 0.53 [− 0.77 to – 0.29]), and lumbo-pelvic region (Hedges g = − 0.48 [− 0.73 to – 0.23]), but large decreases in lower limb force production (Hedges g = − 1.75 [− 2.50 to – 0.99]) and lower limb muscle size (Hedges g = − 1.98 [− 2.72 to – 1.23]). Conclusions: Current exercise countermeasures result in small reductions in BMD during long-duration spaceflight. In contrast, such exercise protocols do not alleviate the reductions in muscle function or muscle size, which may be attributable to the low to moderate loads reported by crewmembers and the interference effect associated with concurrent training. It is recommended that higher-load resistance exercise and the use of high-intensity interval training should be investigated, to determine if such modifications to the reported training practices result in more effective countermeasures to the deleterious effect of long-duration spaceflight on the muscular system. [ABSTRACT FROM AUTHOR]

Lack of time is among the more commonly reported barriers for abstention from exercise programs. The aim of this review was to determine how strength training can be most effectively carried out in a time-efficient manner by critically evaluating research on acute training variables, advanced training techniques, and the need for warm-up and stretching. When programming strength training for optimum time-efficiency we recommend prioritizing bilateral, multi-joint exercises that include full dynamic movements (i.e. both eccentric and concentric muscle actions), and to perform a minimum of one leg pressing exercise (e.g. squats), one upper-body pulling exercise (e.g. pull-up) and one upper-body pushing exercise (e.g. bench press). Exercises can be performed with machines and/or free weights based on training goals, availability, and personal preferences. Weekly training volume is more important than training frequency and we recommend performing a minimum of 4 weekly sets per muscle group using a 6–15 RM loading range (15–40 repetitions can be used if training is performed to volitional failure). Advanced training techniques, such as supersets, drop sets and rest-pause training roughly halves training time compared to traditional training, while maintaining training volume. However, these methods are probably better at inducing hypertrophy than muscular strength, and more research is needed on longitudinal training effects. Finally, we advise restricting the warm-up to exercise-specific warm-ups, and only prioritize stretching if the goal of training is to increase flexibility. This review shows how acute training variables can be manipulated, and how specific training techniques can be used to optimize the training response: time ratio in regard to improvements in strength and hypertrophy. [ABSTRACT FROM AUTHOR]

Linear loading, the two-for-two rule, percent of one repetition maximum (1RM), RM zones, rate of perceived exertion (RPE), repetitions in reserve, set-repetition best, autoregulatory progressive resistance exercise (APRE), and velocity-based training (VBT) are all methods of adjusting resistance training intensity. Each method has advantages and disadvantages that strength and conditioning practitioners should be aware of when measuring and monitoring strength characteristics. The linear loading and 2-for-2 methods may be beneficial for novice athletes; however, they may be limited in their capacity to provide athletes with variation and detrimental if used exclusively for long periods of time. The percent of 1RM and RM zone methods may provide athletes with more variation and greater potential for strength–power adaptations; however, they fail to account for daily changes in athlete's performance capabilities. An athlete's daily readiness can be addressed to various extents by both subjective (e.g., RPE, repetitions in reserve, set-repetition best, and APRE) and objective (e.g., VBT) load adjustment methods. Future resistance training monitoring may aim to include a combination of measures that quantify outcome (e.g., velocity, load, time, etc.) with process (e.g., variability, coordination, efficiency, etc.) relevant to the stage of learning or the task being performed. Load adjustment and monitoring methods should be used to supplement and guide the practitioner, quantify what the practitioner 'sees', and provide longitudinal data to assist in reviewing athlete development and providing baselines for the rate of expected development in resistance training when an athlete returns to sport from injury or large training load reductions. [ABSTRACT FROM AUTHOR]

Master athletes perform high volumes of exercise training yet display lower levels of physical functioning and exercise performance when compared with younger athletes. Several reports in the clinical literature show that long chain n-3 polyunsaturated fatty acid (LC n-3 PUFA) ingestion promotes skeletal muscle anabolism and strength in untrained older persons. There is also evidence that LC n-3 PUFA ingestion improves indices of muscle recovery following damaging exercise in younger persons. These findings suggest that LC n-3 PUFA intake could have an ergogenic effect in master athletes. However, the beneficial effect of LC n-3 PUFA intake on skeletal muscle in response to exercise training in both older and younger persons is inconsistent and, in some cases, generated from low-quality studies or those with a high risk of bias. Other factors such as the choice of placebo and health status of participants also confound interpretation of existing reports. As such, when considered on balance, the available evidence does not indicate that ingestion of LC n-3 PUFAs above current population recommendations (250–500 mg/day; 2 portions of oily fish per week) enhances exercise performance or recovery from exercise training in master athletes. Further work is now needed related to how the dose, duration, and co-ingestion of LC n-3 PUFAs with other nutrients such as amino acids impact the adaptive response to exercise training. This work should also consider how LC n-3 PUFA supplementation may differentially alter the lipid profile of cellular membranes of key regulatory sites such as the sarcolemma, mitochondria, and sarcoplasmic reticulum. [ABSTRACT FROM AUTHOR]

Background: In-season competition and tournaments for team sports can be both long and congested, with some sports competing up to three times per week. During these periods of time, athletes need to prepare technically, tactically and physically for the next fixture and the short duration between fixtures means that, in some cases, physical preparation ceases, or training focus moves to recovery as opposed to progressing adaptations. Objective: The aim of this review was to investigate the effect of training frequency on muscular strength to determine if a potential method to accommodate in-season resistance training, during busy training schedules, could be achieved by utilizing shorter more frequent training sessions across a training week. Methods: A literature search was conducted using the SPORTDiscus, Ovid, PubMed and Scopus databases. 2134 studies were identified prior to application of the following inclusion criteria: (1) maximal strength was assessed, (2) a minimum of two different training frequency groups were included, (3) participants were well trained, and finally (4) compound exercises were included within the training programmes. A Cochrane risk of bias assessment was applied to studies that performed randomized controlled trials and consistency of studies was analysed using I2 as a test of heterogeneity. Secondary analysis of studies included Hedges' g effect sizes (g) and between-study differences were estimated using a random-effects model. Results: Inconsistency of effects between pre- and post-intervention was low within-group (I2 = 0%), and moderate between-group (I2 ≤ 73.95%). Risk of bias was also low based upon the Cochrane risk of bias assessment. Significant increases were observed overall for both upper (p ≤ 0.022) and lower (p ≤ 0.008) body strength, pre- to post-intervention, when all frequencies were assessed. A small effect was observed between training frequencies for upper (g ≤ 0.58) and lower body (g ≤ 0.45). Conclusion: Over a 6–12-week period, there are no clear differences in maximal strength development between training frequencies, in well-trained populations. Such observations may permit the potential for training to be manipulated around competition schedules and volume to be distributed across shorter, but more frequent training sessions within a micro-cycle rather than being condensed into 1–2 sessions per week, in effect, allowing for a micro-dosing of the strength stimuli. [ABSTRACT FROM AUTHOR]

Objective: To investigate the role of muscle thickness changes on changes in strength following 6 weeks of unaccustomed resistance training, via retrospective analysis. Methods: 151 participants completed 6 weeks of no intervention (CONTROL), one-repetition maximum training (1RM-TRAIN), or traditional resistance training (TRAD-TRAIN). Groups were assigned by covariate adaptive randomization. 1RM-TRAIN and TRAD-TRAIN performed elbow flexion exercise on the dominant arm 3 times/week. One-repetition maximum strength and muscle thickness (B-mode ultrasound at 50, 60, and 70% of the anterior upper arm) were assessed pre- and post-training. Direct and indirect effects on strength via each training modality were quantified relative to CONTROL using indicator-coded, change-score mediation analyses for each muscle thickness site. Values are presented as regression coefficients (95% CI). Results: The effect of 1RM-TRAIN on muscle thickness was greater than CONTROL for 60% [0.09 (0.01, 0.17) cm] and 70% [0.09 (0.01,0.18) cm] models. All muscle thickness changes for TRAD-TRAIN were greater than CONTROL: 50% [0.24 (0.16, 0.33) cm], 60% [0.25 (0.17, 0.33) cm], 70% [0.23 (0.14, 0.32) cm]. All direct effects on strength were greater for 1RM-TRAIN versus CONTROL: 50% [1.90 (1.21, 2.58) kg], 60% [1.89 (1.19, 2.58) kg], 70% [1.81 (1.12, 2.51) kg]; and TRAD-TRAIN versus CONTROL: 50% [2.04 (1.29, 2.80) kg], 60% [1.98 (1.22, 2.75) kg], 70% [1.79 (1.05, 2.53) kg]. Compared to CONTROL, there was no indication of an effect of 1RM-TRAIN on strength through muscle thickness (i.e., indirect effect) for 50% [− 0.03 (− 0.17, 0.10)], 60% [− 0.01 (− 0.17, 0.17)], or 70% [0.07 (− 0.09, 0.28)] sites, nor of TRAD-TRAIN for 50% [− 0.11 (− 0.48,0.29)], 60% [− 0.04 (− 0.42, 0.40)], and 70% sites [0.17 (− 0.23,0.58)]. Conclusion: Training-induced changes in muscle thickness do not appear to appreciably mediate training-induced changes in the strength of untrained individuals during the first 6 weeks of training. [ABSTRACT FROM AUTHOR]

Hypertrophy and strength are two common long-term goals of resistance training that are mediated by the manipulation of numerous variables. One training variable that is often neglected but is essential to consider for achieving strength and hypertrophy gains is the movement tempo of particular repetitions. Although research has extensively investigated the effects of different intensities, volumes, and rest intervals on muscle growth, many of the present hypertrophy guidelines do not account for different movement tempos, likely only applying to volitional movement tempos. Changing the movement tempo during the eccentric and concentric phases can influence acute exercise variables, which form the basis for chronic adaptive changes to resistance training. To further elaborate on the already unclear anecdotal evidence of different movement tempos on muscle hypertrophy and strength development, one must acknowledge that the related scientific research does not provide equivocal evidence. Furthermore, there has been no assessment of the impact of duration of particular movement phases (eccentric vs. concentric) on chronic adaptations, making it difficult to draw definitive conclusions in terms of resistance-training recommendations. Therefore, the purpose of this review is to explain how variations in movement tempo can affect chronic adaptive changes. This article provides an overview of the available scientific data describing the impact of movement tempo on hypertrophy and strength development with a thorough analysis of changes in duration of particular phases of movement. Additionally, the review provides movement tempo-specific recommendations as well real training solutions for strength and conditioning coaches and athletes, depending on their goals. [ABSTRACT FROM AUTHOR]