Resistance Exercise Minimal Dose Strategies for Increasing Muscle Strength in the General Population: an Overview

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.

The Connection Between Resistance Training, Climbing Performance, and Injury Prevention

BACKGROUND

Climbing is an intricate sport composed of various disciplines, holds, styles, distances between holds, and levels of difficulty. In highly skilled climbers the potential for further strength-specific adaptations to increase performance may be marginal in elite climbers. With an eye on the upcoming 2024 Paris Olympics, more climbers are trying to maximize performance and improve training strategies. The relationships between muscular strength and climbing performance, as well as the role of strength in injury prevention, remain to be fully elucidated. This narrative review seeks to discuss the current literature regarding the effect of resistance training in improving maximal strength, muscle hypertrophy, muscular power, and local muscular endurance on climbing performance, and as a strategy to prevent injuries.

MAIN BODY

Since sport climbing requires exerting forces against gravity to maintain grip and move the body along the route, it is generally accepted that a climber`s absolute and relative muscular strength are important for climbing performance. Performance characteristics of forearm flexor muscles (hang-time on ledge, force output, rate of force development, and oxidative capacity) discriminate between climbing performance level, climbing styles, and between climbers and non-climbers. Strength of the hand and wrist flexors, shoulders and upper limbs has gained much attention in the scientific literature, and it has been suggested that both general and specific strength training should be part of a climber`s training program. Furthermore, the ability to generate sub-maximal force in different work-rest ratios has proved useful, in examining finger flexor endurance capacity while trying to mimic real-world climbing demands. Importantly, fingers and shoulders are the most frequent injury locations in climbing. Due to the high mechanical stress and load on the finger flexors, fingerboard and campus board training should be limited in lower-graded climbers. Coaches should address, acknowledge, and screen for amenorrhea and disordered eating in climbers.

CONCLUSION

Structured low-volume high-resistance training, twice per week hanging from small ledges or a fingerboard, is a feasible approach for climbers. The current injury prevention training aims to increase the level of performance through building tolerance to performance-relevant load exposure and promoting this approach in the climbing field.

Enhanced skeletal muscle contractile function and corticospinal excitability precede strength and architectural adaptations during lower-limb resistance training

PURPOSE

Evolving investigative techniques are providing greater understanding about the early neuromuscular responses to resistance training among novice exercisers. The aim of this study was to investigate the time-course of changes in muscle contractile mechanics, architecture, neuromuscular, and strength adaptation during the first 6-weeks of lower-limb resistance training.

METHODS

Forty participants: 22 intervention (10 males/12 females; 173.48 ± 5.20 cm; 74.01 ± 13.13 kg) completed 6-week resistance training, and 18 control (10 males/8 females; 175.52 ± 7.64 cm; 70.92 ± 12.73 kg) performed no resistance training and maintained their habitual activity. Radial muscle displacement (Dm) assessed via tensiomyography, knee extension maximal voluntary contraction (MVC), voluntary activation (VA), corticospinal excitability and inhibition via transcranial magnetic stimulation, motor unit (MU) firing rate, and muscle thickness and pennation angle via ultrasonography were assessed before and after 2, 4, and 6-weeks of dynamic lower-limb resistance training or control.

RESULTS

After 2-weeks training, Dm reduced by 19-25% in the intervention group; this was before any changes in neural or morphological measures. After 4-weeks training, MVC increased by 15% along with corticospinal excitability by 16%; however, there was no change in VA, corticospinal inhibition, or MU firing rate. After 6-weeks training there was further MVC increase by 6% along with muscle thickness by 13-16% and pennation angle by 13-14%.

CONCLUSION

Enhanced contractile properties and corticospinal excitability occurred before any muscle architecture, neural, and strength adaptation. Later increases in muscular strength can be accounted for by architectural adaptation.

Unilateral high-load resistance training influences strength changes in the contralateral arm undergoing low-load training

OBJECTIVES

Within-subject training models have become common within the exercise literature. However, it is currently unknown if training one arm with a high load would impact muscle size and strength of the opposing arm training with a low load.

DESIGN

Parallel group.

METHODS

116 participants were randomized to one of three groups that completed 6-weeks (18 sessions) of elbow flexion exercise. Group 1 trained their dominant arm only, beginning with a one-repetition maximum test (≤5 attempts), followed by four sets of exercise using a weight equivalent to 8-12 repetition maximum. Group 2 completed the same training as Group 1 in their dominant arm, while the non-dominant arm completed four sets of low-load exercise (30-40 repetition maximum). Group 3 trained their non-dominant arm only, performing the same low-load exercise as Group 2. Participants were compared for changes in muscle thickness and elbow flexion one-repetition maximum.

RESULTS

The greatest changes in non-dominant strength were present in Groups 1 (Δ 1.5 kg; untrained arm) and 2 (Δ1.1 kg; low-load arm with high load on opposite arm), compared to Group 3 (Δ 0.3 kg; low-load only). Only the arms being directly trained observed changes in muscle thickness (≈Δ 0.25 cm depending on site).

CONCLUSIONS

Within-subject training models are potentially problematic when investigating changes in strength (though not muscle growth). This is based on the finding that the untrained limb of Group 1 saw similar changes in strength as the non-dominant limb of Group 2 which were both greater than the low-load training limb of Group 3.

Fast and Medium Tempo Resistance Training with a Low Number of Repetitions in Trained Men: Effects on Maximal Strength and Power Output

This study aimed to investigate the effects of high load fast and medium tempo back squats using a low number of repetitions on maximal strength and power output. Seventeen participants completed a countermovement jump test and 1-repetition maximum (1-RM) assessment before and after an eight-week intervention. All participants were randomly divided into a fast tempo (FAS: 1/0/1/0) and a medium tempo (MED: 2/0/2/0) resistance training (RT) group and performed three repetitions per set of a Smith back squat exercise with 85% 1-RM intensity. Maximal strength, jump height, peak power and force of the two groups were significantly improved (p < 0.05). In addition, peak velocity significantly increased after the intervention in the FAS group (p < 0.05), but not in the MED group (p > 0.05). A significant interaction effect between training groups was observed for jump height (F (_{1, 30}) = 5.49, p = 0.026, η² = 0.155). However, no significant group by time interaction effects were found between training groups for maximal strength (F (_{1, 30}) = 0.11, p = 0.742, η² = 0.004). Therefore, the two groups showed similar effects in maximal strength, but, compared with the MED group, FAS resistance training with low repetitions caused favorable adaptations in power output in trained men.

Does performing resistance exercise to failure homogenize the training stimulus by accounting for differences in local muscular endurance?

The prescription of resistance exercise often involves administering a set number of repetitions to be completed at a given relative load. While this accounts for individual differences in strength, it neglects to account for differences in local muscle endurance and may result in varied responses across individuals. One way of potentially creating a more homogenous stimulus across individuals involves performing resistance exercise to volitional failure, but this has not been tested and was the purpose of the present study. Individuals completed 2 testing sessions to compare repetitions, ratings of perceived exertion (RPE), muscle swelling and fatigue responses to arbitrary repetition (SET) vs. failure (FAIL) protocols using either 60% or 30% one-repetition maximum. Statistical analyses assessed differences in the variability between protocols. Forty-six individuals (25 females and 21 males) completed the study. There was more variability in the number of repetitions completed during FAIL when compared to SET protocols. Performing the 60% 1RM condition to failure appeared to reduce the variability in muscle swelling (average variance: 60%-SET = .034, 60%-FAIL = .023) and RPE (average variance: 60%-SET = 4.0, 60%-FAIL = 2.5), but did not alter the variability in muscle fatigue. No differences in variability were present between the SET-30% and FAIL-30% protocols for any of the dependent variables. Performing resistance exercise to failure may result in a more homogenous stimulus across individuals, particularly when using moderate to high exercise loads. The prescription of resistance exercise should account for individual differences in local muscle endurance to ensure a similarly effective stimulus across individuals.Highlights There is a large variance in the number of repetitions individuals can complete even when exercising with the same relative load.Ratings of perceived exertion and muscle swelling responses become more homogenous when exercising to volitional failure as compared to using performing a set number of repetitions, particularly when moderate to higher loads are used.The prescription of exercise should take into consideration the individual's local muscle endurance as opposed to choosing an arbitrary number of repetitions to be completed at a given relative load.

Low-Load Resistance Training to Volitional Failure Induces Muscle Hypertrophy Similar to Volume-Matched, Velocity Fatigue

ABSTRACT

Terada, K, Kikuchi, N, Burt, D, Voisin, S, and Nakazato, K. Full title: Low-load resistance training to volitional failure induces muscle hypertrophy similar to volume-matched, velocity fatigue. J Strength Cond Res 36(6): 1576-1581, 2022-We investigated how resistance training (RT) to failure at low load affects acute responses and chronic muscle adaptations compared with low-load RT to velocity fatigue at equal work volume. Twenty-seven subjects performed 8 weeks of bench press twice weekly. Subjects were randomly assigned to one of 3 groups: low-load volitional failure (LVoF, n = 9), low-load velocity fatigue (LVeF, n = 8), and high-load (HL, n = 10). Resistance training comprised 3 sets to failure at 40% one repetition maximum (1RM) in the LVoF group, 3 sets to velocity fatigue (20% lifting velocity loss) at 40% 1RM in the LVeF group, and 3 sets of 8 repetitions at 80% 1RM in the HL group. We measured muscle strength, hypertrophy, endurance, and power at baseline and after the RT program. We also measured muscle swelling and blood lactate after each RT bout to investigate the acute response. There were no differences in total work volume between the LVoF and LVeF groups. Responses to RT were similar between LVoF and LVeF, whether looking at acute muscle swelling, increase in blood lactate, chronic hypertrophy, and strength gain. However, LVoF and LVeF RT triggered different responses to muscle function in comparison with HL training: LVoF and LVeF showed enhanced acute responses and greater chronic endurance gains, but lower chronic strength gains than HL. In conclusion, low-load RT to volitional failure induces muscle hypertrophy similar to volume-matched velocity fatigue.

Reproducibility of strength performance and strength-endurance profiles: A test-retest study

The present study was designed to evaluate the test-retest consistency of repetition maximum tests at standardized relative loads and determine the robustness of strength-endurance profiles across test-retest trials. Twenty-four resistance-trained males and females (age, 27.4 ± 4.0 y; body mass, 77.2 ± 12.6 kg; relative bench press one-repetition maximum [1-RM], 1.19 ± 0.23 kg•kg^-1) were assessed for their 1-RM in the free-weight bench press. After 48 to 72 hours, they were tested for the maximum number of achievable repetitions at 90%, 80% and 70% of their 1-RM. A retest was completed for all assessments one week later. Gathered data were used to model the relationship between relative load and repetitions to failure with respect to individual trends using Bayesian multilevel modeling and applying four recently proposed model types. The maximum number of repetitions showed slightly better reliability at lower relative loads (ICC at 70% 1-RM = 0.86, 90% highest density interval: [0.71, 0.93]) compared to higher relative loads (ICC at 90% 1-RM = 0.65 [0.39, 0.83]), whereas the absolute agreement was slightly better at higher loads (SEM at 90% 1-RM = 0.7 repetitions [0.5, 0.9]; SEM at 70% 1-RM = 1.1 repetitions [0.8, 1.4]). The linear regression model and the 2-parameters exponential regression model revealed the most robust parameter estimates across test-retest trials. Results testify to good reproducibility of repetition maximum tests at standardized relative loads obtained over short periods of time. A complementary free-to-use web application was developed to help practitioners calculate strength-endurance profiles and build individual repetition maximum tables based on robust statistical models.

Comparison of the effects of velocity-based vs. traditional resistance training methods on adaptations in strength, power, and sprint speed: A systematic review, meta-analysis, and quality of evidence appraisal

We estimated the effectiveness of using velocity feedback to regulate resistance training load on changes in muscle strength, power, and linear sprint speed in apparently healthy participants. Academic and grey literature databases were systematically searched to identify randomised trials that compared a velocity-based training intervention to a 'traditional' resistance training intervention that did not use velocity feedback. Standardised mean differences (SMDs) were pooled using a random effects model. Risk of bias was assessed with the Risk of Bias 2 tool and the quality of evidence was evaluated using the GRADE approach. Four trials met the eligibility criteria, comprising 27 effect estimates and 88 participants. The main analyses showed trivial differences and imprecise interval estimates for effects on muscle strength (SMD 0.06, 95% CI -0.51-0.63; I² = 42.9%; 10 effects from 4 studies; low-quality evidence), power (SMD 0.11, 95% CI -0.28-0.49; I² = 13.5%; 10 effects from 3 studies; low-quality evidence), and sprint speed (SMD -0.10, 95% CI -0.72-0.53; I² = 30.0%; 7 effects from 2 studies; very low-quality evidence). The results were robust to various sensitivity analyses. In conclusion, there is currently no evidence that VBT and traditional resistance training methods lead to different alterations in muscle strength, power, or linear sprint speed.

The role of the neural stimulus in regulating skeletal muscle hypertrophy

Resistance training is frequently performed with the goal of stimulating muscle hypertrophy. Due to the key roles motor unit recruitment and mechanical tension play to induce muscle growth, when programming, the manipulation of the training variables is oriented to provoke the correct stimulus. Although it is known that the nervous system is responsible for the control of motor units and active muscle force, muscle hypertrophy researchers and trainers tend to only focus on the adaptations of the musculotendinous unit and not in the nervous system behaviour. To better guide resistance exercise prescription for muscle hypertrophy and aiming to delve into the mechanisms that maximize this goal, this review provides evidence-based considerations for possible effects of neural behaviour on muscle growth when programming resistance training, and future neurophysiological measurement that should be tested when training to increase muscle mass. Combined information from the neural and muscular structures will allow to understand the exact adaptations of the muscle in response to a given input (neural drive to the muscle). Changes at different levels of the nervous system will affect the control of motor units and mechanical forces during resistance training, thus impacting the potential hypertrophic adaptations. Additionally, this article addresses how neural adaptations and fatigue accumulation that occur when resistance training may influence the hypertrophic response and propose neurophysiological assessments that may improve our understanding of resistance training variables that impact on muscular adaptations.

Effect of daily 3-s maximum voluntary isometric, concentric or eccentric contraction on elbow flexor strength

The present study compared a 3-second isometric maximal voluntary contraction (MVC), concentric MVC and eccentric MVC of the elbow flexors performed daily for 5 days a week for 4 weeks for changes in muscle strength and thickness. Young sedentary individuals were assigned to one of three training groups (n=13 per group) that performed either 3-second isometric, concentric or eccentric MVC once a day for 20 days, or to a control group (n=10) that had measurements without training. The participants in the isometric group performed isometric MVC at 55° (0.96rad) elbow flexion, and those in the concentric or eccentric group performed concentric MVC or eccentric MVC between 10° (0.17rad) and 100° (1.75rad) elbow flexion at 30°/s (0.52rad/s) on an isokinetic dynamometer. MVC isometric torque at 20° (0.35rad), 55° (0.96rad), and 90° (1.57 rad) elbow flexion, MVC concentric and eccentric torque at 30°/s (0.52rad/s) and 180°/s (3.14rad/s), and muscle thickness of biceps brachii and brachialis were measured before and several days after the 20^th exercise session. The control group did not show any changes. The eccentric group showed increases (p<0.01) in isometric (three angle average: 10.2±6.4%), concentric (two velocity average: 12.8±9.6%) and eccentric MVC torque (12.2±7.8%). An increase (p<0.05) was limited for isometric MVC torque (6.3±6.0%) in the concentric group, and for eccentric MVC torque (7.2±4.4%) in the isometric group. No significant changes in muscle thickness were evident for all groups. Performing one 3-second MVC a day increased muscle strength, but eccentric MVC produced more potent effects than isometric or concentric MVC.

Muscle growth adaptations to high-load training and low-load training with blood flow restriction in calf muscles

PURPOSE

To compare muscle growth adaptations between traditional high-load training and low-load training with blood flow restriction (BFR) in the calf muscles over 6 weeks.

METHODS

27 trained individuals performed calf exercise in both legs for 6 weeks. Each leg was randomly assigned to one of the two conditions: (1) Traditional (70% of 1RM) training (TRAD); and (2) Low-load (30% of 1RM) training with BFR. In addition, subjects performed standing calf raises with or without BFR. Measures were taken pre- and post-intervention.

RESULTS

For the posterior muscle site, there was no condition (BFR vs. TRAD) × time (pre vs. post) interaction (p = 0.15). In addition, there was no main effect for condition (p = 0.83) or time (p = 0.20). For the lateral muscle site, there was no condition × time interaction (p = 0.47). In addition, there was no main effect for condition (p = 0.10) or time (p = 0.57). For the medial muscle site, there was no condition × time interaction (p = 0.60). In addition, there was no main effect for condition (p = 0.44) or time (p = 0.72). For RPE, there was no condition × time interaction. However, there was a main effect for condition (p < 0.05) with BFR having higher RPE. For discomfort, there was no condition × time interaction. However, there was a main effect for condition (p < 0.001) with the BFR condition displaying higher discomfort.

CONCLUSION

No muscle growth was detected in the calf musculature. BFR was not more effective at eliciting muscle hypertrophy compared to traditional training. However, it was accompanied with higher exertion and discomfort.

Minimal-Dose Resistance Training for Improving Muscle Mass, Strength, and Function: A Narrative Review of Current Evidence and Practical Considerations

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.

The Minimum Effective Training Dose Required for 1RM Strength in Powerlifters

The aim of this multi-experiment paper was to explore the concept of the minimum effective training dose (METD) required to increase 1-repetition-maximum (1RM) strength in powerlifting (PL) athletes. The METD refers to the least amount of training required to elicit meaningful increases in 1RM strength. A series of five studies utilising mixed methods, were conducted using PL athletes & coaches of all levels in an attempt to better understand the METD for 1RM strength. The studies of this multi-experiment paper are: an interview study with elite PL athletes and highly experienced PL coaches (n = 28), an interview and survey study with PL coaches and PL athletes of all levels (n = 137), two training intervention studies with intermediate-advanced PL athletes (n = 25) and a survey study with competitive PL athletes of different levels (n = 57). PL athletes looking to train with a METD approach can do so by performing ~3-6 working sets of 1-5 repetitions each week, with these sets spread across 1-3 sessions per week per powerlift, using loads above 80% 1RM at a Rate of Perceived Exertion (RPE) of 7.5-9.5 for 6-12 weeks and expect to gain strength. PL athletes who wish to further minimize their time spent training can perform autoregulated single repetition sets at an RPE of 9-9.5 though they should expect that strength gains will be less likely to be meaningful. However, the addition of 2-3 back-off sets at ~80% of the single repetitions load, may produce greater gains over 6 weeks while following a 2-3-1 squat-bench press-deadlift weekly training frequency. When utilizing accessory exercises in the context of METD, PL athletes typically utilize 1-3 accessory exercises per powerlift, at an RPE in the range of 7-9 and utilize a repetition range of ~6-10 repetitions.

Skeletal Muscle Quality: A Biomarker for Assessing Physical Performance Capabilities in Young Populations

Muscle quality (MQ), defined as the amount of strength and/or power per unit of muscle mass, is a novel index of functional capacity that is increasingly relied upon as a critical biomarker of muscle health in low functioning aging and pathophysiological adult populations. Understanding the phenotypical attributes of MQ and how to use it as an assessment tool to explore the efficacy of resistance exercise training interventions that prioritize functional enhancement over increases in muscle size may have implications for populations beyond compromised adults, including healthy young adults who routinely perform physically demanding tasks for competitive or occupational purposes. However, MQ has received far less attention in healthy young populations than it has in compromised adults. Researchers and practitioners continue to rely upon static measures of lean mass or isolated measures of strength and power, rather than using MQ, to assess integrated functional responses to resistance exercise training and physical stress. Therefore, this review will critically examine MQ and the evidence base to establish this metric as a practical and important biomarker for functional capacity and performance in healthy, young populations. Interventions that enhance MQ, such as high-intensity stretch shortening contraction resistance exercise training, will be highlighted. Finally, we will explore the potential to leverage MQ as a practical assessment tool to evaluate function and enhance performance in young populations in non-traditional research settings.

The Influence of Movement Tempo During Resistance Training on Muscular Strength and Hypertrophy Responses: A Review

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.

A Retrospective Analysis to Determine Whether Training-Induced Changes in Muscle Thickness Mediate Changes in Muscle Strength

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.

Do exercise-induced increases in muscle size contribute to strength in resistance-trained individuals?

AIM

Previous work in non-resistance-trained individuals has found that an increase in muscle size has no additive effect on changes in strength. However, it is thought that muscle growth is of increased importance for resistance-trained individuals.

PURPOSE

Experiment 1: To examine changes in muscle thickness (MT) and one repetition maximum (1RM) strength following 8 weeks of bi-weekly 1RM practice or traditional training. Experiment 2: To determine whether increasing muscle size increases strength potential when followed by 4 weeks of 1RM training.

METHODS

Participants performed biceps curls for 8 weeks (Experiment 1). One arm performed 4 sets of as many repetitions as possible with approximately 70% of 1RM (TRAD), and the other arm performed a single 1RM. For experiment 2, both arms trained for muscle size and strength.

RESULTS

Experiment 1 (n = 25): for MT, the posterior probabilities favoured the hypothesis that MT changed more in the TRAD condition [mean difference: 50% site 0.15 (-0.09, 0.21) cm; 60% site 0.14 (0.06, 0.23) cm; 70% site 0.17 (0.10, 0.23) cm]. For 1RM strength, each condition changed equivalently. Experiment 2 (n = 18): for MT, the posterior probabilities favoured the hypothesis that MT changed similarly between conditions following a 4-week strength phase. For changes in 1RM strength, the evidence favoured neither hypothesis (i.e. null vs. alternative). Of note, the mean difference between conditions was small [0.72 (4.3) kg].

CONCLUSIONS

1RM training produces similar increases in strength as traditional training. Experiment 2 suggests that increases in muscle mass may not increase the 'potential' for strength gain.

Effects of Low-Load, Higher-Repetition vs. High-Load, Lower-Repetition Resistance Training Not Performed to Failure on Muscle Strength, Mass, and Echo Intensity in Healthy Young Men: A Time-Course Study

Ikezoe, T, Kobayashi, T, Nakamura, M, and Ichihashi, N. Effects of low-load, higher-repetition vs. high-load, lower-repetition resistance training not performed to failure on muscle strength, mass, and echo intensity in healthy young men: A time-course study. J Strength Cond Res 34(12): 3439-3445, 2020-The aim of this study was to compare the effects of low-load, higher-repetition training (LLHR) with those of high-load, lower-repetition training (HLLR) on muscle strength, mass, and echo intensity in healthy young men. Fifteen healthy men (age, 23.1 ± 2.6 years) were randomly assigned to 1 of the 2 groups: LLHR or HLLR group. Resistance training on knee extensor muscles was performed 3 days per week for 8 weeks. One repetition maximum (1RM) strength, maximum isometric strength, muscle thickness, and muscle echo intensity on ultrasonography of the rectus femoris muscle were assessed every 2 weeks. Analysis of variance showed no significant group × time interaction, and only a significant main effect of time was observed for all variables. The 8-week resistance training increased 1RM, maximum isometric muscle strength, and muscle thickness by 36.2-40.9%, 24.0-25.5%, and 11.3-20.4%, respectively, whereas it decreased echo intensity by 8.05-16.3%. Significant improvements in muscle strength, thickness, and echo intensity were observed at weeks 2, 4, and 8, respectively. The lack of difference in time-course changes between LLHR and HLLR programs suggests that low-load training can exert similar effects on muscle mass and characteristics as high-load training by increasing the number of repetitions, even when not performed to failure.

Does resistance training promote enough muscular strength increases to move weak older women to better strength categories?

We compared the magnitude of muscular strength changes among older women occupants of different strength tertiles in response to progressive resistance-training (RT). Additionally, we examined the possibility of older women initially characterized as weak (occupants of the lower tertile of strength status) can achieve a higher muscular strength level to be inserted into a better category (middle or upper tertiles). The present investigation was attended by 113 physically independent older women (>60 years old). Muscular strength was assessed by one-repetition maximum (1RM) tests on chest press, preacher curl, leg extension exercises, and by the isokinetic (ISOK) peak torque of knee extension and flexion at 60 and 180°/s angular velocities. The RT lasted 12 weeks (3 x/week) and consisted of eight exercises for the whole body. The participants were divided into tertiles (LOWER, MIDDLE, and UPPER) according to the performance at baseline for each strength measure. After RT, the LOWER tertile showed more significant magnitude gains than the UPPER tertile to the 1RM in leg extension and preacher curl and isokinetic measurements (6.9-36.3%). A considerable number of older women increased muscular strength enough to move from LOWER to MIDDLE or UPPER tertiles. From our results, it can be inferred that older women occupants of the lower strength tertile show more significant muscular strength gains when compared to their stronger counterparts. Moreover, 12 weeks of RT seem to be sufficient to transfer older women previously characterized as "weak" to a better category.

Is stronger better? Influence of a strength phase followed by a hypertrophy phase on muscular adaptations in resistance-trained men

Although used by resistance-trained individuals, it is unknown if increasing muscle strength prior to hypertrophy training leads to greater muscle growth and strength gains. We investigated muscle thickness and maximum strength in 26 resistance-trained men who were randomly assigned to either: STHT, consisted in a 3-week strength-oriented training period (4x1-3 repetition maximum [RM]) prior to a 5-week hypertrophy-oriented period (4x8-12RM), or HT, which comprised an 8-week hypertrophy-oriented training period. Vastus lateralis muscle thickness, and back squat and leg-press 1-RM were assessed at pre, third week, and after 8 weeks of training. When pre-to-post changes are compared, STHT induced greater muscle growth (p = 0.049; 95%CI = 0.15-3.2%; d = 0.81) and strength gains in the back squat (p = 0.015; 95%CI = 1.5-13%; d = 1.05) and leg-press 45° (p = 0.044; 95%CI = 0.16-9.9%; d = 0.79) compared to HT. Our results support the use of a period to increase muscle strength prior to an HT to increase muscle thickness and maximum strength in resistance-trained men.

The Basics of Training for Muscle Size and Strength: A Brief Review on the Theory

The periodization of resistance exercise is often touted as the most effective strategy for optimizing muscle size and strength adaptations. This narrative persists despite a lack of experimental evidence to demonstrate its superiority. In addition, the general adaptation syndrome, which provides the theoretical framework underlying periodization, does not appear to provide a strong physiological rationale that periodization is necessary. Hans Selye conducted a series of rodent studies which used toxic stressors to facilitate the development of the general adaptation syndrome. To our knowledge, normal exercise in humans has never been shown to produce a general adaptation syndrome. We question whether there is any physiological rationale that a periodized training approach would facilitate greater adaptations compared with nonperiodized approaches employing progressive overload. The purpose of this article is to briefly review currently debated topics within strength and conditioning and provide some practical insight regarding the implications these reevaluations of the literature may have for resistance exercise and periodization. In addition, we provide some suggestions for the continued advancement within the field of strength and conditioning.

Strength testing or strength training: considerations for future research

Maximal strength testing is often performed to assess the efficacy of training programs or as a way to prescribe exercise load. Generally, it is believed that high load exercise is superior to low load exercise at increasing absolute strength, however this is not always the case (i.e. strength increases similarly between groups). We hypothesized that some of the discrepancy in the literature may be related to performing the strength test itself. To investigate this further we reviewed the literature looking for studies comparing high load and low load exercise. The included studies were separated into 'no extra practice' and 'practice'. No extra practice means the strength test was only performed at pre and post whereas practice refers to additional strength tests performed throughout the training intervention. Our results indicated that the differences between high load and low load exercise can be reduced when the group training with a low load is allowed additional exposure to the maximal strength test. This suggests that repeated exposure to strength tests may augment low load training adaptations and influence the outcomes. We discuss potential moderators of this relationship (e.g. how low is the low load, complexity of the skill) and offer considerations for future research. Based on this it would be recommended that when investigating the effects of low load training strength tests should be limited to pre and post intervention or if a control group is utilized then the control group should receive the same number of exposures to the strength test.

Contralateral effects of eccentric resistance training on immobilized arm

This study compared the effects of contralateral eccentric-only (ECC) and concentric-/eccentric-coupled resistance training (CON-ECC) of the elbow flexors on immobilized arm. Thirty healthy participants (18-34 y) were randomly allocated to immobilization only (CTRL; n = 10), immobilization and ECC (n = 10), or immobilization and CON-ECC group (n = 10). The non-dominant arms of all participants were immobilized (8 h·day^-1 ) for 4 weeks, during which ECC and CON-ECC were performed by the dominant (non-immobilized) arm 3 times a week (3-6 sets of 10 repetitions per session) with an 80%-120% and 60%-90% of one concentric repetition maximum (1-RM) load, respectively, matching the total training volume. Arm circumference, 1-RM and maximal voluntary isometric contraction (MVIC) strength, biceps brachii surface electromyogram amplitude (sEMG_RMS ), rate of force development (RFD), and joint position sense (JPS) were measured for both arms before and after immobilization. CTRL showed decreases (P < .05) in MVIC (-21.7%), sEMG_RMS (-35.2%), RFD (-26.0%), 1-RM (-14.4%), JPS (-87.4%), and arm circumference (-5.1%) of the immobilized arm. These deficits were attenuated or eliminated by ECC and CON-ECC, with greater effect sizes for ECC than CON-ECC in MVIC (0.29: +12.1%, vs -0.18: -0.1%) and sEMG_RMS (0.31:17.5% vs -0.15: -5.9%). For the trained arm, ECC showed greater effect size for MVIC than CON-ECC (0.47 vs 0.29), and increased arm circumference (+2.9%), sEMG_RMS (+77.9%), and RDF (+31.8%) greater (P < .05) than CON-ECC (+0.6%, +15.1%, and + 15.8%, respectively). The eccentric-only resistance training of the contralateral arm was more effective to counteract the negative immobilization effects than the concentric-eccentric training.

Effects of Testosterone on Serum Concentrations, Fat-free Mass, and Physical Performance by Population: A Meta-analysis

Testosterone (T) administration (TA) increases serum T and fat-free mass (FFM). Although TA-mediated increases in FFM may enhance physical performance, the data are largely equivocal, which may be due to differences in study populations, the magnitude of change in serum T and FFM, or the performance metrics. This meta-analysis explored effects of TA on serum T, FFM, and performance. Associations between increases in serum T and FFM were assessed, and whether changes in serum T or FFM, study population, or the performance metrics affected performance was determined. A systematic review of double-blind randomized trials comparing TA versus placebo on serum T, FFM, and performance was performed. Data were extracted from 20 manuscripts. Effect sizes (ESs) were assessed using Hedge's g and a random effects model. Data are presented as ES (95% confidence interval). No significant correlation between changes in serum T and FFM was observed (P = .167). Greater increases in serum T, but not FFM, resulted in larger effects on performance. Larger increases in testosterone (7.26 [0.76-13.75]) and FFM (0.80 [0.20-1.41]) were observed in young males, but performance only improved in diseased (0.16 [0.05-0.28]) and older males (0.19 [0.10-0.29]). TA increased lower body (0.12 [0.07-0.18]), upper body (0.26 [0.11-0.40]), and handgrip (0.13 [0.04-0.22]) strength, lower body muscular endurance (0.38 [0.09-0.68]), and functional performance (0.20 [0.00-0.41]), but not lower body power or aerobic endurance. TA elicits increases in serum T and FFM in younger, older, and diseased males; however, the performance-enhancing effects of TA across studies were small, observed mostly in muscular strength and endurance, and only in older and diseased males.

Resistance training-induced improvement in exercise tolerance is not dependent on muscle mass gain in post-menopausal women

Menopause transition may impair muscle function, decreasing exercise tolerance. The torque-duration relationship (hyperbolic curve) forms a practical framework within which exercise tolerance may be explored. In this regard, resistance training (RT) increases the curvature constant of this relationship (W'). Muscle hypertrophy and strength gains have been suggested as possible mediators of RT-induced improvement in W', however, it is unclear what the main mediator is. Higher-volume RT (HV-RT), beyond that recommended by RT-guidelines (i.e. three sets per exercise), may promote greater hypertrophy, but not higher strength gains. Hence, this study aimed to investigate whether greater hypertrophy in HV-RT maximises W' gain when compared to LVRT in postmenopausal women (PW). Fifty-eight PW were randomised to the control group (CTRL), HV-RT (six sets per exercise) or LV-RT (three sets per exercise). They underwent a 12-week RT program and were assessed for W', thigh lean body mass (TLBM) and maximal isometric voluntary contraction (MIVC). The TLBM gain was higher (P < 0.001) in the HV-RT (9.4%) than LV-RT (3.7%). However, both HV-RT and LV-RT similarly increased MIVC (9.7% vs. 16.5%, P = 0.063) and W' (26.4% vs. 34.6% P = 0.163). Additionally, the changes in W' were associated with the changes in TLBM (31%, P = 0.003) and MIVC (52%, P= <0.001). However, when the changes in TLBM and MIVC were inserted into the predictive model, only the MIVC (33%, P = 0.002) was a predictor of W'. Thus, although HV-RT promoted greater hypertrophy than LV-RT, HV-RT does not seem to maximise W' in PW.

Resistance Training Volume Enhances Muscle Hypertrophy, but Not Strength in Postmenopausal Women: A Randomized Controlled Trial

Nascimento de Oliveira Júnior, G, de Freitas Rodrigues de Sousa, J, Augusto da Silva Carneiro, M, Martins, FM, Santagnello, SB, Campos Souza, MV, and Orsatti, FL. Resistance training volume enhances muscle hypertrophy, but not strength in postmenopausal women: a randomized controlled trial. J Strength Cond Res XX(X): 000-000, 2020-Among several possible resistance training (RT) variables to be manipulated, the training volume has been considered as a critical variable to maximize RT-induced hypertrophy. Many of the studies that compared one set of RT with 3 sets have failed to show a difference in muscle hypertrophy in older adults. However, it is not clear whether further increases in RT volume (i.e., 6 sets) would result in even greater RT-related hypertrophy than 3 sets in older adults. This study aimed to investigate whether higher-volume RT (HV-RT) maximizes gains in lean body mass and muscle strength (MS) when compared with lower-volume RT (LV-RT) in postmenopausal women (PW). Fifty-eight PW were randomized into 1 of the 3 groups: control group (CT, no exercise), HV-RT (6 sets per exercise), and LV-RT (3 sets per exercise). Volunteers took part in a supervised training program (leg press 45°, leg extension, leg curl and standing calf raises) and were assessed for leg lean mass (LLM; dual X-ray absorptiometry) and lower limb MS (leg press and leg extension; 1 repetition maximum [1RM]) before and after 12 weeks of RT. Both HV-RT and LV-RT groups increased (p < 0.05) LLM and MS when compared with the CT group. Higher increases in LLM gains were observed for the HV-RT group when compared with the LV-RT group (6.1 and 2.3%, p < 0.001). Both HV-RT and LV-RT groups similarly increased 1RM in the leg press and leg extension. Thus, there seems to be a dose-response relationship between RT volume and muscle hypertrophy, but not for MS gains in PW.

Effects of In-Season Velocity- Versus Percentage-Based Training in Academy Rugby League Players

PURPOSE

To compare the effects of velocity-based training (VBT) vs percentage-based training (PBT) on strength, speed, and jump performance in academy rugby league players during a 7-wk in-season mesocycle.

METHODS

A total of 27 rugby league players competing in the Super League U19s Championship were randomized to VBT (n = 12) or PBT (n = 15). Both groups completed a 7-wk resistance-training intervention (2×/wk) that involved the back squat. The PBT group used a fixed load based on a percentage of 1-repetition maximum (1-RM), whereas the VBT group used a modifiable load based on individualized velocity thresholds. Biomechanical and perceptual data were collected during each training session. Back-squat 1-RM, countermovement jump, reactive strength index, sprint times, and back-squat velocity at 40-90% 1-RM were assessed pretraining and posttraining.

RESULTS

The PBT group showed likely to most likely improvements in 1-RM strength and reactive strength index, whereas the VBT group showed likely to very likely improvements in 1-RM strength, countermovement jump height, and back-squat velocity at 40% and 60% 1-RM. Sessional velocity and power were most likely greater during VBT compared with PBT (standardized mean differences = 1.8-2.4), while time under tension and perceptual training stress were likely lower (standardized mean differences = 0.49-0.66). The improvement in back-squat velocity at 60% 1-RM was likely greater following VBT compared with PBT (standardized mean difference = 0.50).

CONCLUSION

VBT can be implemented during the competitive season, instead of traditional PBT, to improve training stimuli, decrease training stress, and promote velocity-specific adaptations.

Assessing differential responders and mean changes in muscle size, strength, and the crossover effect to 2 distinct resistance training protocols

The objective of this study was to determine differences in 2 distinct resistance training protocols and if true variability can be detected after accounting for random error. Individuals (n = 151) were randomly assigned to 1 of 3 groups: (i) a traditional exercise group performing 4 sets to failure; (ii) a group performing a 1-repetition maximum (1RM) test; and (iii) a time-matched nonexercise control group. Both exercise groups performed 18 sessions of elbow flexion exercise over 6 weeks. While both training groups increased 1RM strength similarly (∼2.4 kg), true variability was only present in the traditional exercise group (true variability = 1.80 kg). Only the 1RM group increased untrained arm 1RM strength (1.5 kg), while only the traditional group increased ultrasound measured muscle thickness (∼0.23 cm). Despite these mean increases, no true variability was present for untrained arm strength or muscle hypertrophy in either training group. In conclusion, these findings demonstrate the importance of taking into consideration the magnitude of random error when classifying differential responders, as many studies may be classifying high and low responders as those who have the greatest amount of random error present. Additionally, our mean results demonstrate that strength is largely driven by task specificity, and the crossover effect of strength may be load dependent. Novelty Many studies examining differential responders to exercise do not account for random error. True variability was present in 1RM strength gains, but the variability in muscle hypertrophy and isokinetic strength changes could not be distinguished from random error. The crossover effect of strength may differ based on the protocol employed.

Re-examination of 1- vs. 3-Sets of Resistance Exercise for Pre-spaceflight Muscle Conditioning: A Systematic Review and Meta-Analysis

Background: Recommendations on resistance training (RT) set-volume protocols in preparation for spaceflight muscular strength conditioning remains equivocal. A meta-analysis was performed on the effects of single-set (S), or three-set (M3) RT on muscular strength per exercise for different body segments and joint types (multi-joint and single-joint). Methods: Computerized searches were performed on PubMed, MEDLINE and SPORTDiscus™. Twelve studies were considered appropriate according to pre-set eligibility criteria. Outcomes analyzed were pre-to-post-muscular strength change on; multi-joint and single-joint combined; upper body only; lower body only; multi-joint exercises only; single-joint exercises only. Results: Upper body exercise analysis on combined subjects and untrained subjects only reported greater but not significant strength gains with M3 (ES 0.37; 95% CI 0.09-0.82; P = 0.11 and ES 0.35; 95% CI-0.49 to 1.19; P = 0.42). Trained only subjects reported superior strength gains with M3 (ES 0.63; 95% CI 0.34-0.92; P = <0.0001). Lower body exercise on combined subjects and untrained subjects only reported superior strength gains with M3 (ES 0.35; 95% CI 0.10-0.60; P = 0.006 and ES 0.49; 95% CI 0.14-0.83; P = 0.005). Trained subjects only observed greater but not significant strength gains with M3 (ES 0.18; 95% CI -0.23 to 0.58; P = 0.39). Multi-joint exercise on combined subjects reported greater strength gains with M3 (ES 0.83; 95% CI 0.14-1.51; P = 0.02). Trained only subjects reported greater strength gains with M3 (ES 0.52; 95% CI 0.10-0.94; P = 0.02). Single-joint exercise on combined subjects and untrained only observed greater strength gains for M3 (ES 0.49; 95% CI 0.26-0.72; P = <0.0001 and ES 0.56; 95% CI 0.21-0.91; P = 0.002). Trained only subjects reported greater but not significant strength gains with M3 (ES 0.37; 95% CI -0.01 to 0.75; P = 0.06). Conclusion: For astronauts in space-flight preparation, the findings suggest that M3 training appears to be preferable over S for developing muscular strength. Nevertheless, depending on the physical conditioning of the crew member or tight pre-flight scheduling, S is still able to provide a positive strength training stimulus.

The impact of a familiarization session on the magnitude and stability of active and passive pelvic floor muscle forces measured through intravaginal dynamometry

AIMS

The aim of this study was to investigate the impact of task familiarization on (1) the magnitude and (2) the repeatability of active and passive properties of the female pelvic floor muscles (PFMs) measured using automated intra-vaginal dynamometry.

METHODS

Women attended three laboratory sessions at one-week intervals. After receiving initial task instruction and feedback at the start of the first session, standardized instructions were given while women performed maximal effort voluntary contractions of their PFMs with the dynamometer arms open at two different diameters and kept their PFMs relaxed while the dynamometer arms opened to 40 mm at two speeds. Outcomes included baseline force, peak force, relative peak forces (N), rate of force development (N/s) and stiffness. Between session effects were tested for all outcomes using one-way ANOVAs. Intra-class correlation coefficients (ICCs) and minimal detectable change values were computed within each session and between sessions 1 and 2 and sessions 2 and 3.

RESULTS

Twenty nulliparous women (mean age = 35 ± 15 years) participated. No differences in the mean values were found across the three visits for any outcomes. Within sessions, neither ICC nor minimal detectable change differed among sessions and between-session ICC values were not different between visits 1 and 2 and visits 2 and 3.

CONCLUSIONS

There is no evidence of a familiarization effect over a two-week period on the amplitude nor repeatability of dynamometric measures of active or passive PFM properties recorded from nulliparous women.

Effect of Resistance Training Frequency on Gains in Muscular Strength: A Systematic Review and Meta-Analysis

BACKGROUND

Current recommendations on resistance training (RT) frequency for gains in muscular strength are based on extrapolations from limited evidence on the topic, and thus their practical applicability remains questionable.

OBJECTIVE

To elucidate this issue, we conducted a systematic review and meta-analysis of the studies that compared muscular strength outcomes with different RT frequencies.

METHODS

To carry out this review, English-language literature searches of the PubMed/MEDLINE, Scopus, and SPORTDiscus databases were conducted. The meta-analysis was performed using a random-effects model. The meta-analysis models were generated with RT frequencies classified as a categorical variable as either 1, 2, 3, or 4+ times/week, or, if there were insufficient data in subgroup analyses, the training frequencies were categorized as 1, 2, or 3 times/week. Subgroup analyses were performed for potential moderators, including (1) training volume; (2) exercise selection for the 1 repetition maximum (RM) test (for both multi-joint and single-joint exercises); (3) upper and lower body strength gains; (4) training to muscular failure (for studies involving and not involving training to muscular failure); (5) age (for both middle-aged/older adults and young adults); and (6) sex (for men and for women). The methodological quality of studies was appraised using the modified Downs and Black checklist.

RESULTS

A total of 22 studies were found to meet the inclusion criteria. The average score on the Downs and Black checklist was 18 (range 13-22 points). Four studies were classified as being of good methodological quality, while the rest were classified as being of moderate methodological quality. Results of the meta-analysis showed a significant effect (p = 0.003) of RT frequency on muscular strength gains. Effect sizes increased in magnitude from 0.74, 0.82, 0.93, and 1.08 for training 1, 2, 3, and 4+ times per week, respectively. A subgroup analysis of volume-equated studies showed no significant effect (p = 0.421) of RT frequency on muscular strength gains. The subgroup analysis for exercise selection for the 1RM test suggested a significant effect of RT frequency on multi-joint (p < 0.001), but not single-joint, 1RM test results (p = 0.324). The subgroup analysis for upper and lower body showed a significant effect of frequency (p = 0.004) for upper body, but not lower body, strength gains (p = 0.070). In the subgroup analysis for studies in which the training was and was not carried out to muscular failure, no significant effect of RT frequency was found. The subgroup analysis for the age groups suggested a significant effect of training frequency among young adults (p = 0.024), but not among middle-aged and older adults (p = 0.093). Finally, the subgroup analysis for sex indicated a significant effect of RT frequency on strength gains in women (p = 0.030), but not men (p = 0.190).

CONCLUSIONS

The results of the present systematic review and meta-analysis suggest a significant effect of RT frequency as higher training frequencies are translated into greater muscular strength gains. However, these effects seem to be primarily driven by training volume because when the volume is equated, there was no significant effect of RT frequency on muscular strength gains. Thus, from a practical standpoint, greater training frequencies can be used for additional RT volume, which is then likely to result in greater muscular strength gains. However, it remains unclear whether RT frequency on its own has significant effects on strength gain. It seems that higher RT frequencies result in greater gains in muscular strength on multi-joint exercises in the upper body and in women, and, finally, in contrast to older adults, young individuals seem to respond more positively to greater RT frequencies. More evidence among resistance-trained individuals is needed as most of the current studies were performed in untrained participants.

Interpreting Adaptation to Concurrent Compared with Single-Mode Exercise Training: Some Methodological Considerations

Incorporating both endurance and resistance training into an exercise regime is termed concurrent training. While there is evidence that concurrent training can attenuate resistance training-induced improvements in maximal strength and muscle hypertrophy, research findings are often equivocal, with some suggesting short-term concurrent training may instead further enhance muscle hypertrophy versus resistance training alone. These observations have questioned the validity of the purported 'interference effect' on muscle hypertrophy with concurrent versus single-mode resistance training. This article aims to highlight some methodological considerations when interpreting the concurrent training literature, and, in particular, the degree of changes in strength and muscle hypertrophy observed with concurrent versus single-mode resistance training. Individual training status clearly influences the relative magnitude and specificity of both training adaptation and post-exercise molecular responses in skeletal muscle. The training status of participants is therefore likely a key modulator of the degree of adaptation and interference seen with concurrent training interventions. The divergent magnitudes of strength gain versus muscle hypertrophy induced by resistance training also suggests most concurrent training studies are likely to observe more substantial changes in (and in turn, any potential interference to) strength compared with muscle hypertrophy. Both the specificity and sensitivity of measures used to assess training-induced changes in strength and muscle hypertrophy also likely influence the interpretation of concurrent training outcomes. Finally, the relative importance of any modulation of hypertrophic versus strength adaptation with concurrent training should be considered in context with the relevance of training-induced changes in these variables for enhancing athletic performance and/or functional capacity. Taken together, these observations suggest that aside from various training-related factors, additional non-training-related variables, including participant training status and the measures used to assess changes in strength and muscle hypertrophy, are important considerations when interpreting the outcomes of concurrent training interventions.

The Effect of Weekly Set Volume on Strength Gain: A Meta-Analysis

Background

Strength training set organisation and its relationship to the development of muscular strength have yet to be clearly defined. Current meta-analytical research suggests that different population groups have distinctive muscular adaptations, primarily due to the prescription of the strength training set dose.

Objectives

We conducted a meta-analysis with restrictive inclusion criteria and examined the potential effects of low (LWS), medium (MWS) or high weekly set (HWS) strength training on muscular strength per exercise. Secondly, we examined strength gain variations when performing multi-joint or isolation exercises, and probed for a potential relationship between weekly set number and stage of subjects’ training (trained versus untrained).

Methods

Computerised searches were performed on PubMed, MEDLINE, SWETSWISE, EMBASE and SPORTDiscus™ using the terms ‘strength training’, ‘resistance training’, ‘single sets’, ‘multiple sets’ and ‘volume’. As of September 2016, 6962 potentially relevant studies were identified. After review, nine studies were deemed eligible per pre-set inclusion criteria. Primary data were pooled using a random-effect model. Outcomes for strength gain, strength gain with multi-joint and isolation exercise were analysed for main effects. Sensitivity analyses were calculated for several subgroups by separating the data set and by calculation of separate analyses for each subgroup. Heterogeneity between studies was assessed using the Cochran Q and I² statistics.

Results

Pre- versus post-training strength analysis comprised 61 treatment groups from nine studies. For combined multi-joint and isolation exercises, pre- versus post- training strength gains were greater with HWS compared with LWS [mean effect size (ES) 0.18; 95% CI 0.06–0.30; p = 0.003]. The mean ES for LWS was 0.82 (95% CI 0.47–1.17). The mean ES for HWS was 1.01 (95% CI 0.70–1.32). Separate analysis of the effects of pre- versus post-training strength for LWS or MWS observed marginally greater strength gains with MWS compared with LWS (ES 0.15; 95% CI 0.01–0.30; p = 0.04). The mean ES for LWS was 0.83 (95% CI 0.53–1.13). The mean ES for MWS was 0.98 (95% CI 0.62–1.34). For multi-joint exercises, greater strength gains were observed with HWS compared with LWS (ES 0.18; 95% CI 0.01–0.34; p = 0.04). The mean ES for LWS was 0.81 (95% CI 0.65–0.97). The mean ES for HWS was 1.00 (95% CI 0.77–1.23). For isolation exercises, greater strength gains were observed with HWS compared with LWS (ES 0.23; 95% CI 0.06–0.40; p = 0.008). The mean ES for LWS was 0.95 (95% CI 0.30–1.60). The mean ES for HWS was 1.10 (95% CI 0.26–1.94). For multi-joint and isolation exercise-specific one repetition maximum (1 RM), marginally greater strength gains were observed with HWS compared with LWS (ES 0.14; 95% CI −0.01 to 0.29; p = 0.06). The mean ES for LWS was 0.80 (95% CI 0.47–1.13). The mean ES for HWS was 0.97 (95% CI 0.68–1.26).

Conclusion

This meta-analysis presents additional evidence regarding a graded dose–response relationship between weekly sets performed and strength gain. The use of MWS and HWS was more effective than LWS, with LWS producing the smallest pre- to post-training strength difference. For novice and intermediate male trainees, the findings suggest that LWSs do not lead to strength gains compared with MWS or HWS training. For those trainees in the middle ground, not a novice and not advanced, the existing data provide a relationship between weekly sets and strength gain as set configurations produced different pre- to post-training strength increases. For well trained individuals, the use of either MWS or HWS may be an appropriate dose to produce strength gains.

The Association of Handgrip Strength and Mortality: What Does It Tell Us and What Can We Do With It?

The relationship between grip strength and mortality is often used to underscore the importance of resistance exercise in physical activity guidelines. However, grip strength does not appear to appreciably change following traditional resistance training. Thus, grip strength could be considered reflective of strength independent of resistance exercise. If true, grip strength is not necessarily informing us of the importance of resistance exercise as an adult, but potentially highlighting inherent differences between individuals who are stronger at "baseline" compared to their weaker counterpart. The purpose of this article is to discuss: (1) potential factors that may influence grip strength and (2) hypothesize strategies that may be able to influence grip strength and ultimately attain a higher baseline level of strength. Although there appears to be a limited ability to augment grip strength as an adult, there may be critical periods during growth/development during which individuals can establish a higher baseline. Establishing a high baseline of strength earlier in life may have long-term implications related to mortality and disease.

Reduced Volume 'Daily Max' Training Compared to Higher Volume Periodized Training in Powerlifters Preparing for Competition-A Pilot Study

The present study looked to examine reduced volume ‘daily max’ (near max loads) training compared to higher volume periodized training in powerlifters preparing for competition. Ten competitive powerlifters were split into 2 groups (MAX group and PER group) and participated in a 10-week training intervention either following a “daily max” training protocol or a traditional periodized training protocol while preparing for competition. All participants underwent 1RM testing for squat (SQ), bench press (BP) and deadlift (DL) prior to the 10-week intervention. The MAX group performed single sets of single repetitions using a load equating to an RPE rating of 9–9.5 while the PER group performed higher volume periodized training with loads ranging from 70%1RM up to 93%1RM as well as a taper at the final weeks of the training intervention. Both groups were tested after the 10-week training intervention at the Greek IPF-affiliate National Championships. In the PER group, powerlifting (PL) total increased for P1 and P3 by 2% and 6.5% respectively while P2 experienced no change. In the MAX group PL total increased for P1 and P2 by 4.8% and 4.2% respectively while it decreased by 0.5%, 3.4% and 5% for P3, P4 and P5 respectively. In the MAX group peri PL total increased for P1–4 by 3.6%, 4.2%, 4.5% and 1.8% respectively while it decreased by 1.2% for P5. The results of this pilot study show that single-set, single-rep, RPE based ‘daily max’ training may be a favorable strategy for some beginner-intermediate powerlifters preparing for competition while it may lead to performance decreases for others. Further, it suggests that performance may be comparable to traditional periodized training during shorter training cycles, though future work with larger samples is needed to further test this. Practically ‘daily max’ training may be useful for PL athletes looking to maintain strength during periods with limited training time available.

Effects of Consecutive Versus Non-consecutive Days of Resistance Training on Strength, Body Composition, and Red Blood Cells

Health authorities worldwide recommend 2–3 days per week of resistance training (RT) performed ∼48–72 h apart. However, the influence of recovery period between RT sessions on muscle strength, body composition, and red blood cells (RBCs) are unclear.

Aim: Examine the effects of three consecutive (C) or non-consecutive (NC) days of RT per week for 12 weeks on strength, body composition, and RBCs.

Methods: Thirty young, healthy and recreationally active males were randomly assigned to 3 C (∼24 h between sessions) or NC (∼48–72 h between sessions) days of RT per week for 12 weeks. Both groups performed three sets of 10 repetitions at 10-repetition maximum (RM) of leg press, latissimus pulldown, leg curl, shoulder press, and leg extension for each session. Ten RM and body composition were assessed pre- and post-RT. RBC parameters were measured on the first session before RT, and 0 and 24 h post-3rd session in untrained (week 1) and trained (week 12) states.

Results: No training × group interaction was found for all strength and body composition parameters (p = 0.075–0.974). Training increased strength for all exercises, bone mineral density, and total body mass via increased lean and bone mass (p < 0.001). There was no interaction (p = 0.076–0.994) and RT induced temporal changes in all RBC parameters (p < 0.001–0.003) except RBC corrected for plasma volume changes (time × training interaction; p = 0.001). Training increased hematocrit and lowered mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration (p = 0.001–0.041) but did not alter uncorrected RBC, hemoglobin, mean corpuscular volume and RBC distribution width (p = 0.178–0.797).

Conclusion: Both C and NC RT induced similar improvements in strength and body composition, and changes in RBC parameters.