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Pediatrics Jun 2020Resistance training is becoming more important as an integral part of comprehensive sport training regimens, school physical education classes, and after-school fitness... (Review)
Review
Resistance training is becoming more important as an integral part of comprehensive sport training regimens, school physical education classes, and after-school fitness programs. The increasing number of youth who are involved in sport activities, coupled with the health problems of inactivity and being overweight, have resulted in increased interest in resistance training. Secular declines in measures of muscular fitness in modern-day youth highlight the need for participation in youth resistance training for nonathletes as well as athletes. Parents often ask pediatricians to offer advice regarding the safety, benefits, and implementation of an effective resistance-training program. This report is a revision of the 2008 American Academy of Pediatrics policy statement and reviews current information and research on the benefits and risks of resistance training for children and adolescents.
Topics: Adolescent; Child; Humans; Physical Education and Training; Physical Fitness; Resistance Training
PubMed: 32457216
DOI: 10.1542/peds.2020-1011 -
Journal of Strength and Conditioning... Dec 2017Schoenfeld, BJ, Grgic, J, Ogborn, D, and Krieger, JW. Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and... (Meta-Analysis)
Meta-Analysis Review
Schoenfeld, BJ, Grgic, J, Ogborn, D, and Krieger, JW. Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. J Strength Cond Res 31(12): 3508-3523, 2017-The purpose of this article was to conduct a systematic review of the current body of literature and a meta-analysis to compare changes in strength and hypertrophy between low- vs. high-load resistance training protocols. Searches of PubMed/MEDLINE, Cochrane Library, and Scopus were conducted for studies that met the following criteria: (a) an experimental trial involving both low-load training [≤60% 1 repetition maximum (1RM)] and high-load training (>60% 1RM); (b) with all sets in the training protocols being performed to momentary muscular failure; (c) at least one method of estimating changes in muscle mass or dynamic, isometric, or isokinetic strength was used; (d) the training protocol lasted for a minimum of 6 weeks; (e) the study involved participants with no known medical conditions or injuries impairing training capacity. A total of 21 studies were ultimately included for analysis. Gains in 1RM strength were significantly greater in favor of high- vs. low-load training, whereas no significant differences were found for isometric strength between conditions. Changes in measures of muscle hypertrophy were similar between conditions. The findings indicate that maximal strength benefits are obtained from the use of heavy loads while muscle hypertrophy can be equally achieved across a spectrum of loading ranges.
Topics: Adaptation, Physiological; Humans; Hypertrophy; Muscle Strength; Muscle, Skeletal; Resistance Training
PubMed: 28834797
DOI: 10.1519/JSC.0000000000002200 -
Medicine and Science in Sports and... Mar 2009In order to stimulate further adaptation toward specific training goals, progressive resistance training (RT) protocols are necessary. The optimal characteristics of... (Review)
Review
In order to stimulate further adaptation toward specific training goals, progressive resistance training (RT) protocols are necessary. The optimal characteristics of strength-specific programs include the use of concentric (CON), eccentric (ECC), and isometric muscle actions and the performance of bilateral and unilateral single- and multiple-joint exercises. In addition, it is recommended that strength programs sequence exercises to optimize the preservation of exercise intensity (large before small muscle group exercises, multiple-joint exercises before single-joint exercises, and higher-intensity before lower-intensity exercises). For novice (untrained individuals with no RT experience or who have not trained for several years) training, it is recommended that loads correspond to a repetition range of an 8-12 repetition maximum (RM). For intermediate (individuals with approximately 6 months of consistent RT experience) to advanced (individuals with years of RT experience) training, it is recommended that individuals use a wider loading range from 1 to 12 RM in a periodized fashion with eventual emphasis on heavy loading (1-6 RM) using 3- to 5-min rest periods between sets performed at a moderate contraction velocity (1-2 s CON; 1-2 s ECC). When training at a specific RM load, it is recommended that 2-10% increase in load be applied when the individual can perform the current workload for one to two repetitions over the desired number. The recommendation for training frequency is 2-3 d x wk(-1) for novice training, 3-4 d x wk(-1) for intermediate training, and 4-5 d x wk(-1) for advanced training. Similar program designs are recommended for hypertrophy training with respect to exercise selection and frequency. For loading, it is recommended that loads corresponding to 1-12 RM be used in periodized fashion with emphasis on the 6-12 RM zone using 1- to 2-min rest periods between sets at a moderate velocity. Higher volume, multiple-set programs are recommended for maximizing hypertrophy. Progression in power training entails two general loading strategies: 1) strength training and 2) use of light loads (0-60% of 1 RM for lower body exercises; 30-60% of 1 RM for upper body exercises) performed at a fast contraction velocity with 3-5 min of rest between sets for multiple sets per exercise (three to five sets). It is also recommended that emphasis be placed on multiple-joint exercises especially those involving the total body. For local muscular endurance training, it is recommended that light to moderate loads (40-60% of 1 RM) be performed for high repetitions (>15) using short rest periods (<90 s). In the interpretation of this position stand as with prior ones, recommendations should be applied in context and should be contingent upon an individual's target goals, physical capacity, and training status.
Topics: Adult; Athletic Performance; Evidence-Based Medicine; Humans; Hypertrophy; Muscle Contraction; Muscle, Skeletal; Physical Endurance; Resistance Training; Rest; Societies, Medical; United States
PubMed: 19204579
DOI: 10.1249/MSS.0b013e3181915670 -
Applied Physiology, Nutrition, and... Apr 2022The purpose of this paper was to conduct a systematic review and meta-analysis of studies that compared muscle hypertrophy and strength gains between resistance training... (Meta-Analysis)
Meta-Analysis Review
The purpose of this paper was to conduct a systematic review and meta-analysis of studies that compared muscle hypertrophy and strength gains between resistance training protocols employing very low (VLL < 30% of 1-repetition maximum (RM) or >35RM), low (LL30%-59% of 1RM, or 16-35RM), moderate (ML60%-79% of 1RM, or 8-15RM), and high (HL ≥ 80% of 1RM, or ≤7RM) loads with matched volume loads (sets × repetitions × weight). A pooled analysis of the standardized mean difference for 1RM strength outcomes across the studies showed a benefit favoring HL vs. LL and vs. ML and favoring ML vs. LL. The LL and VLL results showed little difference. A pooled analysis of the standardized mean difference for hypertrophy outcomes across all studies showed no differences between training loads. Our findings indicate that when the volume load is equal between conditions, the highest loads induce superior dynamic strength gains. Alternatively, hypertrophic adaptations were similar irrespective of the load magnitude. Training with higher loads elicits greater gains in 1RM muscle strength when compared to lower loads, even when the volume load is equal between conditions. Muscle hypertrophy is similar irrespective of the magnitude of the load, even when the volume load is equal between conditions.
Topics: Adaptation, Physiological; Humans; Hypertrophy; Muscle Strength; Muscle, Skeletal; Resistance Training
PubMed: 35015560
DOI: 10.1139/apnm-2021-0515 -
Sports Medicine (Auckland, N.Z.) Nov 2016A number of resistance training (RT) program variables can be manipulated to maximize muscular hypertrophy. One variable of primary interest in this regard is RT... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
A number of resistance training (RT) program variables can be manipulated to maximize muscular hypertrophy. One variable of primary interest in this regard is RT frequency. Frequency can refer to the number of resistance training sessions performed in a given period of time, as well as to the number of times a specific muscle group is trained over a given period of time.
OBJECTIVE
We conducted a systematic review and meta-analysis to determine the effects of resistance training frequency on hypertrophic outcomes.
METHODS
Studies were deemed eligible for inclusion if they met the following criteria: (1) were an experimental trial published in an English-language refereed journal; (2) directly compared different weekly resistance training frequencies in traditional dynamic exercise using coupled concentric and eccentric actions; (3) measured morphologic changes via biopsy, imaging, circumference, and/or densitometry; (4) had a minimum duration of 4 weeks; and (5) used human participants without chronic disease or injury. A total of ten studies were identified that investigated RT frequency in accordance with the criteria outlined.
RESULTS
Analysis using binary frequency as a predictor variable revealed a significant impact of training frequency on hypertrophy effect size (P = 0.002), with higher frequency being associated with a greater effect size than lower frequency (0.49 ± 0.08 vs. 0.30 ± 0.07, respectively). Statistical analyses of studies investigating training session frequency when groups are matched for frequency of training per muscle group could not be carried out and reliable estimates could not be generated due to inadequate sample size.
CONCLUSIONS
When comparing studies that investigated training muscle groups between 1 to 3 days per week on a volume-equated basis, the current body of evidence indicates that frequencies of training twice a week promote superior hypertrophic outcomes to once a week. It can therefore be inferred that the major muscle groups should be trained at least twice a week to maximize muscle growth; whether training a muscle group three times per week is superior to a twice-per-week protocol remains to be determined.
Topics: Exercise; Humans; Hypertrophy; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Resistance Training
PubMed: 27102172
DOI: 10.1007/s40279-016-0543-8 -
Sports Medicine (Auckland, N.Z.) Mar 2023This systematic review with meta-analysis investigated the influence of resistance training proximity-to-failure on muscle hypertrophy. (Meta-Analysis)
Meta-Analysis
BACKGROUND AND OBJECTIVE
This systematic review with meta-analysis investigated the influence of resistance training proximity-to-failure on muscle hypertrophy.
METHODS
Literature searches in the PubMed, SCOPUS and SPORTDiscus databases identified a total of 15 studies that measured muscle hypertrophy (in healthy adults of any age and resistance training experience) and compared resistance training performed to: (A) momentary muscular failure versus non-failure; (B) set failure (defined as anything other than momentary muscular failure) versus non-failure; or (C) different velocity loss thresholds.
RESULTS
There was a trivial advantage for resistance training performed to set failure versus non-failure for muscle hypertrophy in studies applying any definition of set failure [effect size=0.19 (95% confidence interval 0.00, 0.37), p=0.045], with no moderating effect of volume load (p=0.884) or relative load (p=0.525). Given the variability in set failure definitions applied across studies, sub-group analyses were conducted and found no advantage for either resistance training performed to momentary muscular failure versus non-failure for muscle hypertrophy [effect size=0.12 (95% confidence interval -0.13, 0.37), p=0.343], or for resistance training performed to high (>25%) versus moderate (20-25%) velocity loss thresholds [effect size=0.08 (95% confidence interval -0.16, 0.32), p=0.529].
CONCLUSION
Overall, our main findings suggest that (i) there is no evidence to support that resistance training performed to momentary muscular failure is superior to non-failure resistance training for muscle hypertrophy and (ii) higher velocity loss thresholds, and theoretically closer proximities-to-failure do not always elicit greater muscle hypertrophy. As such, these results provide evidence for a potential non-linear relationship between proximity-to-failure and muscle hypertrophy.
Topics: Humans; Muscle, Skeletal; Resistance Training; Muscle Strength; Hypertrophy
PubMed: 36334240
DOI: 10.1007/s40279-022-01784-y -
Sports Medicine (Auckland, N.Z.) Jul 2022In resistance training, periodization is often used in an attempt to promote development of strength and muscle hypertrophy. However, it remains unclear how resistance... (Meta-Analysis)
Meta-Analysis
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.
Topics: Adaptation, Physiological; Humans; Hypertrophy; Muscle Strength; Muscle, Skeletal; Resistance Training
PubMed: 35044672
DOI: 10.1007/s40279-021-01636-1 -
European Journal of Sport Science Sep 2017Although the effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy have been investigated in several studies,... (Review)
Review
Although the effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy have been investigated in several studies, the findings are equivocal and the practical implications remain unclear. In an attempt to provide clarity on the topic, we performed a systematic literature search of PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, and Physiotherapy Evidence Database (PEDro) electronic databases. Six studies were found to have met the inclusion criteria: (a) an experimental trial published in an English-language peer-reviewed journal; (b) the study compared the use of short (≤60 s) to long (>60 s) inter-set rest intervals in a traditional dynamic resistance exercise using both concentric and eccentric muscle actions, with the only difference in resistance training among groups being the inter-set rest interval duration; (c) at least one method of measuring changes in muscle mass was used in the study; (d) the study lasted for a minimum of four weeks, employed a training frequency of ≥2 resistance training days per week, and (e) used human participants without known chronic disease or injury. Current evidence indicates that both short and long inter-set rest intervals may be useful when training for achieving gains in muscle hypertrophy. Novel findings involving trained participants using measures sensitive to detect changes in muscle hypertrophy suggest a possible advantage for the use of long rest intervals to elicit hypertrophic effects. However, due to the paucity of studies with similar designs, further research is needed to provide a clear differentiation between these two approaches.
Topics: Humans; Hypertrophy; Muscle Strength; Muscle, Skeletal; Research Design; Resistance Training; Rest; Time Factors
PubMed: 28641044
DOI: 10.1080/17461391.2017.1340524 -
The Cochrane Database of Systematic... Dec 2013Fibromyalgia is characterized by chronic widespread pain that leads to reduced physical function. Exercise training is commonly recommended as a treatment for management... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Fibromyalgia is characterized by chronic widespread pain that leads to reduced physical function. Exercise training is commonly recommended as a treatment for management of symptoms. We examined the literature on resistance training for individuals with fibromyalgia. Resistance training is exercise performed against a progressive resistance with the intention of improving muscle strength, muscle endurance, muscle power, or a combination of these.
OBJECTIVES
To evaluate the benefits and harms of resistance exercise training in adults with fibromyalgia. We compared resistance training versus control and versus other types of exercise training.
SEARCH METHODS
We searched nine electronic databases (The Cochrane Library, MEDLINE, EMBASE, CINAHL, PEDro, Dissertation Abstracts, Current Controlled Trials, World Health Organization (WHO) International Clinical Trials Registry Platform, AMED) and other sources for published full-text articles. The date of the last search was 5 March 2013. Two review authors independently screened 1856 citations, 766 abstracts and 156 full-text articles. We included five studies that met our inclusion criteria.
SELECTION CRITERIA
Selection criteria included: a) randomized clinical trial, b) diagnosis of fibromyalgia based on published criteria, c) adult sample, d) full-text publication, and e) inclusion of between-group data comparing resistance training versus a control or other physical activity intervention.
DATA COLLECTION AND ANALYSIS
Pairs of review authors independently assessed risk of bias and extracted intervention and outcome data. We resolved disagreements between the two review authors and questions regarding interpretation of study methods by discussion within the pairs or when necessary the issue was taken to the full team of 11 members. We extracted 21 outcomes of which seven were designated as major outcomes: multidimensional function, self reported physical function, pain, tenderness, muscle strength, attrition rates, and adverse effects. We evaluated benefits and harms of the interventions using standardized mean differences (SMD) or mean differences (MD) or risk ratios or Peto odds ratios and 95% confidence intervals (CI). Where two or more studies provided data for an outcome, we carried out a meta-analysis.
MAIN RESULTS
The literature search yielded 1865 citations with five studies meeting the selection criteria. One of the studies that had three arms contributed data for two comparisons. In the included studies, there were 219 women participants with fibromyalgia, 95 of whom were assigned to resistance training programs. Three randomized trials compared 16 to 21 weeks of moderate- to high-intensity resistance training versus a control group. Two studies compared eight weeks of progressive resistance training (intensity as tolerated) using free weights or body weight resistance exercise versus aerobic training (ie, progressive treadmill walking, indoor and outdoor walking), and one study compared 12 weeks of low-intensity resistance training using hand weights (1 to 3 lbs (0.45 to 1.36 kg)) and elastic tubing versus flexibility exercise (static stretches to major muscle groups).Statistically significant differences (MD; 95% CI) favoring the resistance training interventions over control group(s) were found in multidimensional function (Fibromyalgia Impact Questionnaire (FIQ) total decreased 16.75 units on a 100-point scale; 95% CI -23.31 to -10.19), self reported physical function (-6.29 units on a 100-point scale; 95% CI -10.45 to -2.13), pain (-3.3 cm on a 10-cm scale; 95% CI -6.35 to -0.26), tenderness (-1.84 out of 18 tender points; 95% CI -2.6 to -1.08), and muscle strength (27.32 kg force on bilateral concentric leg extension; 95% CI 18.28 to 36.36).Differences between the resistance training group(s) and the aerobic training groups were not statistically significant for multidimensional function (5.48 on a 100-point scale; 95% CI -0.92 to 11.88), self reported physical function (-1.48 units on a 100-point scale; 95% CI -6.69 to 3.74) or tenderness (SMD -0.13; 95% CI -0.55 to 0.30). There was a statistically significant reduction in pain (0.99 cm on a 10-cm scale; 95% CI 0.31 to 1.67) favoring the aerobic groups.Statistically significant differences were found between a resistance training group and a flexibility group favoring the resistance training group for multidimensional function (-6.49 FIQ units on a 100-point scale; 95% CI -12.57 to -0.41) and pain (-0.88 cm on a 10-cm scale; 95% CI -1.57 to -0.19), but not for tenderness (-0.46 out of 18 tender points; 95% CI -1.56 to 0.64) or strength (4.77 foot pounds torque on concentric knee extension; 95% CI -2.40 to 11.94). This evidence was classified low quality due to the low number of studies and risk of bias assessment. There were no statistically significant differences in attrition rates between the interventions. In general, adverse effects were poorly recorded, but no serious adverse effects were reported. Assessment of risk of bias was hampered by poor written descriptions (eg, allocation concealment, blinding of outcome assessors). The lack of a priori protocols and lack of care provider blinding were also identified as methodologic concerns.
AUTHORS' CONCLUSIONS
The evidence (rated as low quality) suggested that moderate- and moderate- to high-intensity resistance training improves multidimensional function, pain, tenderness, and muscle strength in women with fibromyalgia. The evidence (rated as low quality) also suggested that eight weeks of aerobic exercise was superior to moderate-intensity resistance training for improving pain in women with fibromyalgia. There was low-quality evidence that 12 weeks of low-intensity resistance training was superior to flexibility exercise training in women with fibromyalgia for improvements in pain and multidimensional function. There was low-quality evidence that women with fibromyalgia can safely perform moderate- to high-resistance training.
Topics: Adult; Exercise; Female; Fibromyalgia; Humans; Randomized Controlled Trials as Topic; Resistance Training
PubMed: 24362925
DOI: 10.1002/14651858.CD010884 -
The Cochrane Database of Systematic... Jul 2009Muscle weakness in old age is associated with physical function decline. Progressive resistance strength training (PRT) exercises are designed to increase strength. (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Muscle weakness in old age is associated with physical function decline. Progressive resistance strength training (PRT) exercises are designed to increase strength.
OBJECTIVES
To assess the effects of PRT on older people and identify adverse events.
SEARCH STRATEGY
We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialized Register (to March 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 2), MEDLINE (1966 to May 01, 2008), EMBASE (1980 to February 06 2007), CINAHL (1982 to July 01 2007) and two other electronic databases. We also searched reference lists of articles, reviewed conference abstracts and contacted authors.
SELECTION CRITERIA
Randomised controlled trials reporting physical outcomes of PRT for older people were included.
DATA COLLECTION AND ANALYSIS
Two review authors independently selected trials, assessed trial quality and extracted data. Data were pooled where appropriate.
MAIN RESULTS
One hundred and twenty one trials with 6700 participants were included. In most trials, PRT was performed two to three times per week and at a high intensity. PRT resulted in a small but significant improvement in physical ability (33 trials, 2172 participants; SMD 0.14, 95% CI 0.05 to 0.22). Functional limitation measures also showed improvements: e.g. there was a modest improvement in gait speed (24 trials, 1179 participants, MD 0.08 m/s, 95% CI 0.04 to 0.12); and a moderate to large effect for getting out of a chair (11 trials, 384 participants, SMD -0.94, 95% CI -1.49 to -0.38). PRT had a large positive effect on muscle strength (73 trials, 3059 participants, SMD 0.84, 95% CI 0.67 to 1.00). Participants with osteoarthritis reported a reduction in pain following PRT(6 trials, 503 participants, SMD -0.30, 95% CI -0.48 to -0.13). There was no evidence from 10 other trials (587 participants) that PRT had an effect on bodily pain. Adverse events were poorly recorded but adverse events related to musculoskeletal complaints, such as joint pain and muscle soreness, were reported in many of the studies that prospectively defined and monitored these events. Serious adverse events were rare, and no serious events were reported to be directly related to the exercise programme.
AUTHORS' CONCLUSIONS
This review provides evidence that PRT is an effective intervention for improving physical functioning in older people, including improving strength and the performance of some simple and complex activities. However, some caution is needed with transferring these exercises for use with clinical populations because adverse events are not adequately reported.
Topics: Activities of Daily Living; Aged; Humans; Muscle Weakness; Randomized Controlled Trials as Topic; Recovery of Function; Resistance Training
PubMed: 19588334
DOI: 10.1002/14651858.CD002759.pub2