Training to Fatigue: The Answer for Standardization When Assessing Muscle Hypertrophy?

Effects of low-load blood flow restriction on the venous system in comparison to traditional low-load and high-load exercises

Purpose: Blood-Flow-Restriction (BFR) training provides the ability to achieve hypertrophy effects even though only light mechanical loads are applied. However, its impact on venous pressures and function are still unknown. Therefore, the present study investigates the influence of BFR-training on intravascular venous pressure and venous function in comparison to control exercises with low or high mechanical loads. Methods: In a randomized cross-over design, ten healthy men (27.6 ± 6.4 years) underwent three trials of unilateral knee-extensor exercise with three different training protocols, low-load- (LL-RT, 30% of the individual 1-repetition-maximum, 1RM), low-load BFR- (LL-BFR-RT, 30% 1RM, 50% limb occlusion pressure, LOP) and high-load resistance exercise (HL-RT, 75% 1RM). Exercise protocols contain about four sets of knee extension exercise (Range-of-Motion: 0-0-95°), separated by 60 s of rest. Each set was performed until volitional muscle failure. For analysis of changes in intravascular venous pressures and venous function, a venous catheter was placed at the exercising leg before each trial. Whereas venous pressures were recorded throughout the exercise trials, phlebodynamometric investigations were performed before and after each trial. Furthermore, subjective pain perception during and after exercise was accessed by visual analogue scale. One-way ANOVA was used to assess mean differences between training protocols, while two-way repeated-measures ANOVA (rANOVA; time x condition) was performed to compare changes in measures over time among conditions. Data were given as means ± standard deviation (SD). Results: In comparison to the exercise trials without venous occlusion, total workload was significantly lower in the LL-BFR-RT (LL-RT: 1745 ± 604 kg vs LL-BFR-RT: 1274 ± 237 kg vs HL-RT: 1847 ± 367 kg, p = 0.004) without indicating statistical differences in venous pressures during the exercise sets (interaction: p = 0.140) or pain perception (interaction: p = 0.574). Similarly, phlebodynamometric assessment of venous function (e.g. refill-time of the venous system pre-vs. post exercise trials-LL-RT: 29.7 ± 11.0 s vs 25.5 ± 9.6 s, LL-BFR-RT: 26.6 ± 13.0 s vs 27.3 ± 13.8 s, HL-RT: 25.9 ± 10.9 s vs 23.1 ± 8.2 s) revealed no time (p = 0.156), condition effect (p = 0.802) or their interactions (p = 0.382). Conclusion: The present study is the first one describing the acute effects of LL-BFR-RT to muscle failure on venous pressures and function in comparison to a LL- and HL-RT in the lower limbs. In contrast to the existing literature, LL-BFR-RT does not elevate the venous pressures during exercise higher than a comparative exercise without BFR and does not show any adverse effects on venous function after the exercise.

The Effects of Training Load During Dietary Intervention Upon Fat Loss: A Randomized Crossover Trial

Purpose: To date no studies have compared resistance training loading strategies combined with dietary intervention for fat loss. Methods: Thus, we performed a randomised crossover design comparing four weeks of heavier- (HL; ~80% 1RM) and lighter-load (LL; ~60% 1RM) resistance training, combined with calorie restriction and dietary guidance, including resistance trained participants (n=130; males=49, females=81). Both conditions performed low-volume, (single set of 9 exercises, 2x/week) effort matched (to momentary failure), but non-work-matched protocols. Testing was completed pre- and post-each intervention. Fat mass (kg) was the primary outcome, and a smallest effect size of interest (SESOI) was established at 3.3% loss of baseline bodyweight. Body fat percentage, lean mass, and strength (7-10RM) for chest press, leg press, and pull-down exercises were also measured. An 8-week washout period of traditional training with normal calorie interspersed each intervention. Results: Both interventions showed small statistically equivalent (within the SESOI) reductions in fat mass (HL: -0.67 kg [95%CI -0.91 to 0.42]; LL: -0.55 kg [95%CI -0.80 to -0.31]) which were also equivalent between conditions (HL - LL: -0.113 kg [95%CI -0.437 kg to 0.212 kg]). Changes in body fat percentage and lean mass were also minimal. Strength increases were small, similar between conditions, and within a previously determined SESOI for the population included (10.1%). Conclusions: Fat loss reductions are not impacted by resistance training load; both HL and LL produce similar, yet small, changes to body composition over a 4-week intervention. However, the maintenance of both lean mass and strength highlights the value of resistance training during dietary intervention.

Comparison of traditional vs. lighter load strength training on fat-free mass, strength, power and affective responses in middle and older-aged adults: A pilot randomized trial

OBJECTIVES

Strength training is widely recommended to improve strength, muscle mass and power. However, the feasibility and potential efficacy of strength training using lighter loads near failure on these outcomes in middle and older-aged adults remains unclear.

METHODS

23 community-living adults were randomized into two groups: Traditional strength training (ST) (8-12 repetitions) or a lighter load, higher repetitions (LLHR) (20-24 repetitions) group. Participants performed a full-body workout (twice a week) with 8 exercises at a perceived exertion of 7-8 (0-10 scale) for 10 weeks. Post-testing was performed by an assessor blinded to group assignments. An analysis of covariance (ANCOVA) was used to examine between group differences using baseline values as a covariate.

RESULTS

The study involved individuals with a mean age of 59 years, of which 61 % were women. The LLHR group demonstrated a high attendance rate of 92 % (9.5 %) and reported leg press exercise RPE of 7.1 (0.53), along with a session feeling scale of 2.0 (1.7). There was a trivial difference in fat free mass (FFM) favoring LLHR vs ST [0.27 kg 95 % CI (-0.87, 1.42)]. The ST group exhibited superior increases in leg press 1 repetition maximum (1RM) strength [-14 kg (-23, -5)], while the LLHR group showed greater strength endurance increases (65 % 1RM) [8 repetitions (2, 14)]. Leg press power [41 W (-42, 124)] and exercise efficacy [-3.8 (-21.2, 13.5)] demonstrated trivial between-group differences.

CONCLUSION

A pragmatic, full-body strength training program with lighter loads taken close to failure appears to be a viable option for promoting muscular adaptations in middle- and older-aged adults. These results are exploratory and require a larger trial for confirmation.

Acute muscular and cardiovascular responses to high load training with pre-exercise blood flow restriction

PURPOSE

The purpose of this study is to examine the acute muscular and cardiovascular responses to applying blood flow restriction (BFR) before high-load training.

METHODS

Forty trained individuals visited the lab on three occasions. On Visit 1, participants completed paperwork and performed strength assessments. During Visits 2 and 3, participants completed four exercise conditions (one in each arm during each visit) as follows: (1) traditional resistance training (TRAD), (2) low load training with BFR (LLBFR), (3) low repetition high load training with pre-exercise BFR (PreBFR), and (4) low repetition traditional training (LRTRAD). Blood pressure, muscle thickness (MT), and isometric strength (ISO) were measured before and after exercise.

RESULTS

Data are displayed as means (SD). Immediately following exercise, MT in TRAD was greater compared with PreBFR (mean difference = 0.18[0.30] cm, p < 0.001) and LRTRAD (mean difference = 0.28[0.30] cm, p < 0.001). In addition, LLBFR demonstrated greater MT compared with PreBFR (mean difference = 0.24[0.30] cm, p < 0.001]. Immediately following exercise, ISO was lower in TRAD compared with PreBFR (mean difference = 33.8[46.9]N, p < 0.001) and the LRTRAD condition (mean difference = 32.8[50.4]N, p < 0.001). In addition, ISO was lower in LLBFR compared with PreBFR (mean difference = 43.9 [47.4]N, p < 0.001) and LRTRAD (mean difference = 42.9 [43.8]N, p < 0.001). Immediately following exercise, systolic blood pressure was greater in TRAD compared with PreBFR and LRTRAD.

CONCLUSION

The application of BFR before engaging in high-load training does not seem to augment the muscular responses to exercise when compared with traditional high loads alone; however, it may pose less demand on the cardiovascular system.

Training in the Initial Range of Motion Promotes Greater Muscle Adaptations Than at Final in the Arm Curl

OBJECTIVE

The effects of ROM manipulation on muscle strength and hypertrophy response remain understudied in long-term interventions. Thus, we compared the changes in strength and regional muscle hypertrophy after training in protocols with different ranges of motion (ROM) in the seated dumbbell preacher curl exercise using a within-participant experimental design.

DESIGN AND METHODS

Nineteen young women had one arm randomly assigned to train in the initial ROM (INITIAL_ROM: 0°-68°; 0° = extended elbow) while the contralateral arm trained in the final ROM (FINAL_ROM: 68°-135°), three times per week over an eight-week study period. Pre- and post-training assessments included one repetition maximum (1RM) testing in the full ROM (0°-135°), and measurement of biceps brachii cross-sectional area (CSA) at 50% and 70% of humerus length. Paired t-tests were used to compare regional CSA changes between groups, the sum of CSA changes at 50% and 70% (CSA_summed), and the strength response between the training protocols.

RESULTS

The INITIAL_ROM protocol displayed a greater CSA increase than FINAL_ROM protocol at 70% of biceps length (p = 0.001). Alternatively, we observed similar increases between the protocols for CSA at 50% (p = 0.311) and for CSA_summed (p = 0.111). Moreover, the INITIAL_ROM protocol displayed a greater 1RM increase than FINAL_ROM (p < 0.001).

CONCLUSIONS

We conclude that training in the initial angles of elbow flexion exercise promotes greater distal hypertrophy of the biceps brachii muscle in untrained young women. Moreover, the INITIAL_ROM condition promotes a greater dynamic strength increase when tested at a full ROM compared to the FINAL_ROM.

Urinary Incontinence in Elite Female Athletes

PURPOSE OF REVIEW

To summarize the current understanding on the epidemiology, pathophysiology, and management strategies of urinary incontinence (UI) in female athletes, highlighting findings specific to nulliparous elite athletes.

RECENT FINDINGS

UI occurs in about 20-50% of female athletes of all ages and parity status, around 40% for younger nulliparous athletes, and is more prevalent in high-impact sports. Possible contributing factors to UI in female elite athletes include pelvic floor laxity and bladder neck descent, pelvic floor muscle fatigue, low energy availability, and hypermobility syndrome. In female elite athletes, urinary symptoms negatively affect quality of life, although the effects of symptoms on exercise participation are not well understood. Current management strategies are primarily conservative and centered on behavioral modifications and pelvic floor muscle physiotherapy. UI in female elite athletes appears to be multifactorial. Clarifying how individual factors influence UI in this population will inform athlete counseling, prevention, and treatment strategies.

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.

Neuromuscular and mean force changes during a fatiguing bout of exercise with and without blood flow restriction

Surface electromyography (EMG) and mean force can be used to identify motor unit excitation and fatigue. Low-load resistance training with blood flow restriction (LL+BFR) may result in earlier fatigue and maximal muscle fibre recruitment compared to low-load resistance training (LL). The purpose of this investigation was to examine EMG and force responses during LL versus LL+BFR. Thirteen males (mean ± standard deviation = 24±4 years) completed a bout (1×30) of leg extension muscle actions at 30% of their 1 repetition maximum LL and LL+BFR while force, EMG amplitude, and EMG mean power frequency (EMG MPF) were recorded. EMG amplitude increased (74.2%) and EMG MPF decreased (22.6%) similarly during both conditions. There was no significant difference in mean force during the first 3 repetitions between LL+BFR (477.3±132.3 N) and LL (524.3±235.1 N) conditions, but mean force was lower during the last 3 repetitions for LL+BFR (459.7±179.3 N) compared to LL (605.4±276.4 N). The results of the present study indicated that a fatiguing bout of leg extension muscle actions performed LL and LL+BFR elicited similar neuromuscular responses. There was a significant difference in mean force during the last 3 repetitions (LL>LL+BFR) that may have been due to differences in the time spent near peak force.

Longitudinal Effects of Traditional and Rest Redistribution Set Configurations on Explosive-Strength and Strength-Endurance Manifestations

ABSTRACT

Janicijevic, D, González-Hernández, JM, Jiménez-Reyes, P, Márquez, G, and García-Ramos, A. Longitudinal effects of traditional and rest redistribution set configurations on explosive-strength and strength-endurance manifestations. J Strength Cond Res XX(X): 000-000, 2022-This study aimed to compare the long-term effects of resistance training programs based on traditional and rest redistribution set configurations on explosive-strength and strength-endurance performance of lower-body and upper-body muscles. Thirty physically active men were randomly assigned to a traditional group (TRG: 6 sets of 5 repetitions with 3 minutes of interset rest) or a rest redistribution group (RRG: 30 sets of 1 repetition with 31 seconds of interrepetition rest). The training program lasted 6 weeks (2 sessions·wk-1), and in each training session, the squat and bench press exercises were performed with maximal concentric effort against approximately the 75% of the 1 repetition maximum. Before and after training, explosive-strength performance (peak velocity reached at submaximal loads during the countermovement jump and bench press throw) and strength-endurance performance (mean set velocity of 10 repetitions using both traditional and cluster sets in the squat and bench press) were assessed. Significant improvements in all dependent variables were observed after training for both the TRG (p ≤ 0.004; effect size [ES] = 0.63-3.06) and RRG (p ≤ 0.001; ES = 0.58-3.23). The magnitude of the changes was comparable for both groups with the only exception of the larger improvements observed in the RRG for the bench press mean set velocity using both traditional (ES = 0.77) and cluster (ES = 0.82) set configurations. Traditional and rest redistribution set configurations are equally effective to improve lower-body explosive strength, lower-body strength endurance, and upper-body explosive strength, whereas rest redistribution set configurations could induce greater adaptations in upper-body strength endurance.

Injuries and Strength Training Practices in Collegiate Tennis

Strength and conditioning practices may influence injury rates in the sport of tennis. Methods: Coaches reported the number injuries over the past year. Coaches were also surveyed on whether their training program included training related to upper-body or lower-body strength, power, muscle growth, and eccentric exercise. Separate regression analyses were run in the upper and lower body to examine the relationship between injuries and participation in training focused on strength, power, growth, and maximal eccentric exercise. A total of 111 coaches were surveyed. The most frequent injuries observed were ankle sprains (144 injures), followed by paraspinal muscle strains (126 injuries). When pooled, there were a total of 355 lower-body and 260 upper-body injuries. Strength and conditioning practices explained 9.9% of the variance of injury rates in the upper body (R² = 0.099). The only significant predictor of upper-body injury was participation in upper-body muscle growth training (β = 1.613, p = 0.013). In addition, training practices explained 11.1% of the variance of injury in the lower body (R² = 0.111). Coaches value injury prevention exercise, sports-specific training and flexibility and mobility training the most, with muscle growth and maximal power ranked lowest. Additionally, the most frequent injuries observed in collegiate tennis players were ankle sprains (144 injures), followed by paraspinal muscle strains (126 injuries).

Isolated Soy Protein Supplementation Combined With Resistance Training Improves Muscle Strength, Mass, and Physical Performance of Aging Female Mice

Background/Purpose: In recent years, the aging population has gradually increased, and the aging process is accompanied by health-associated problems, such as loss of muscle mass and weakness. Therefore, it is important to explore alternative strategies for improving the health status and physical fitness of the aged population. In this study, we investigated the effect of soy protein supplementation combined with resistance training on changes in the muscle mass, muscle strength, and functional activity performance of aging mice.

Methods: Female Institute of Cancer Research (ICR) mice were divided into four groups (n = 8 per group): sedentary control (SC), isolated soy protein (ISP) supplementation, resistance training (RT), and a combination of ISP and RT (ISP + RT). The mice in designated groups received oral ISP supplementation (0.123 g/kg/day), RT (5 days/week for a period of 4 weeks), or a combination of both ISP plus RT for 4 weeks. Afterward, we assessed muscle strength, endurance, and anaerobic endurance performance and analyzed blood biochemical and pathological tissue sections to investigate whether there were adverse effects or not in mice.

Results: ISP supplementation effectively improved the muscle mass, muscle endurance, and endurance performance of aging female mice. The RT group not only showed similar results with ISP but also increased muscle strength and glycogen content. Nevertheless, the combination of ISP supplementation and RT had greater beneficial effects on muscle strength, physical performance, and glycogen levels (p < 0.05). In addition, the combination of ISP supplementation and RT had significantly increased type II muscle percentage and cross-sectional area (p < 0.05).

Conclusion: Although ISP or RT alone improved muscle mass and performance, the combination of ISP with RT showed greater beneficial effects in aging mice. Our findings suggest that regular exercise along with protein supplementation could be an effective strategy to improve overall health and physical fitness among the elderly.

Stubborn Exercise Responders-Where to Next?

There is a wide variance in the magnitude of physiological adaptations after resistance or endurance training. The incidence of “non” or “poor” responders to training has been reported to represent as high as 40% of the project’s sample. However, the incidence of poor responders to training can be ameliorated with manipulation of either the training frequency, intensity, type and duration. Additionally, global non-response to cardio-respiratory fitness training is eliminated when evaluating several health measures beyond just the target variables as at least one or more measure improves. More research is required to determine if altering resistance training variables results in a more favourable response in individuals with an initial poor response to resistance training. Moreover, we recommend abandoning the term “poor” responders, as ultimately the magnitude of change in cardiorespiratory fitness in response to endurance training is similar in “poor” and “high” responders if the training frequency is subsequently increased. Therefore, we propose “stubborn” responders as a more appropriate term. Future research should focus on developing viable physiological and lifestyle screening tests that identify likely stubborn responders to conventional exercise training guidelines before the individual engages with training. Exerkines, DNA damage, metabolomic responses in blood, saliva and breath, gene sequence, gene expression and epigenetics are candidate biomarkers that warrant investigation into their relationship with trainability. Crucially, viable biomarker screening tests should show good construct validity to distinguish between different exercise loads, and possess excellent sensitivity and reliability. Furthermore “red flag” tests of likely poor responders to training should be practical to assess in clinical settings and be affordable and non-invasive. Early identification of stubborn responders would enable optimization of training programs from the onset of training to maintain exercise motivation and optimize the impact on training adaptations and health.

Neuromuscular Impact of Acute Hypertrophic Resistance Loading With and Without Blood-Flow Restriction

Exploring acute neuromuscular fatigue induced by different modalities of resistance exercise would help understand the adaptation subsequent to specific training programs. Therefore, we investigated the acute impact of high-intensity and low-intensity blood flow-restricted resistance exercise on the development of explosive torque throughout the torque-time curve. Seventeen healthy, young participants were included in a randomized, counterbalanced within-subjects design study, in which participants underwent two experimental conditions, separated by a 1-wk period. Low-intensity blood-flow restricted exercise and high-intensity resistance exercise were performed using dynamic elbow flexion at 20 and 75% of 1 repetition maximum, respectively. Maximal voluntary contraction (MVC) and the sequential rate of torque development (absolute and relative) were measured before and after exercise. Both protocols elicited a similar decrement in MVC (~ 25%) and in the peak rate of torque development after exercise (~ 45%). The absolute rate of torque development (0-50 and 50-100 ms) was also reduced (p<0.05) similarly between conditions. After normalizing torque values to MVC, this was only sustained for the rate of torque development 0-50ms (p<0.05). We found that both exercise protocols induced similar acute attenuation of the absolute rate of torque development up to the first 100 ms of MVC. We also demonstrated that the reduction in the rate of torque development between 50-100ms (in both protocols) was largely explained by an acute deficit in muscle strength post-exercise. Conversely, the impact of each protocol on the first 50ms of muscle torque did not depend on lower levels of muscle strength after exercise.

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.

Postoperative Rehabilitation and Return to Sport Following Multiligament Knee Reconstruction

Multiligament knee injuries (MLKIs) are debilitating injuries that increasingly occur in young athletes. Return to sport (RTS) has historically been considered unlikely due to the severity of these injuries. Reporting in the literature regarding objective outcomes following MLKI, including RTS, is lacking, as are clear protocols for both rehabilitation progressions and RTS testing. RTS following MLKI is a complex process that requires an extended recovery duration compared to other surgery types. Progressions through postoperative rehabilitation and RTS should be thoughtful, gradual, and criterion based. After effective anatomic reconstruction to restore joint stability, objective measures of recovery including range of motion, strength, movement quality, power, and overall conditioning guide decision-making throughout the recovery process. It is important to frame the recovery process of the athlete in the context of the severity of their injury, as it is typically slower and less linear. Improved reporting on objective outcomes will enhance our understanding of recovery expectations within this population by highlighting persistent deficits that may interfere with a full recovery, including RTS.

Lighter-Load Exercise Produces Greater Acute- and Prolonged-Fatigue in Exercised and Non-Exercised Limbs

Purpose: The present study compared the fatigue and perceptual responses to volume-load matched heavier- and lighter- load resistance exercise to momentary failure in both a local/exercised, and non-local/non-exercised limb. Methods: Eleven resistance-trained men undertook unilateral maximal voluntary contraction (MVC) testing for knee extension prior to and immediately, 24 hr- and 48 hr- post heavier (80% MVC) and lighter  (40% MVC) load dynamic unilateral knee extension exercise. Only the dominant leg of each participant was exercised to momentary failure using heavier and lighter loads, and perceptions of discomfort were measured immediately upon exercise cessation. Results: Point estimates and confidence intervals suggested that immediately post-exercise there was greater fatigue in both the exercised and non-exercised legs for the lighter- load condition. At 24 hr the exercised leg under the heavier-load condition had recovered to pre-exercise strength; however, the exercised leg under lighter- load condition had still not fully recovered by 48 hr. For the non-exercised leg, only the lighter-load condition induced fatigue; however, recovery had occurred by 48 hr. Median discomfort ratings were statistically significantly different (Z = -2.232, p = .026) between lighter and heavier loads (10 [IQR = 0] and 8 [IQR = 3], respectively). Conclusions: This study suggests that lighter-load resistance exercise induces greater fatigue in both the exercised- and non-exercised limbs, compared to heavier-load resistance exercise. These findings may have implications for exercise frequency as it may be possible to engage in heavier-load resistance exercise more frequently than a volume-load matched protocol using lighter loads.Abbreviations CI: Confidence intervals: ES: Effect size: MVC: Maximum voluntary contraction; Nm:Newton meters; RM: Repetition maximum; SD: Standard deviation; SI: Strength index.

Timing of Creatine Supplementation around Exercise: A Real Concern?

Creatine has been considered an effective ergogenic aid for several decades; it can help athletes engaged in a variety of sports and obtain performance gains. Creatine supplementation increases muscle creatine stores; several factors have been identified that may modify the intramuscular increase and subsequent performance benefits, including baseline muscle Cr content, type II muscle fibre content and size, habitual dietary intake of Cr, aging, and exercise. Timing of creatine supplementation in relation to exercise has recently been proposed as an important consideration to optimise muscle loading and performance gains, although current consensus is lacking regarding the ideal ingestion time. Research has shifted towards comparing creatine supplementation strategies pre-, during-, or post-exercise. Emerging evidence suggests greater benefits when creatine is consumed after exercise compared to pre-exercise, although methodological limitations currently preclude solid conclusions. Furthermore, physiological and mechanistic data are lacking, in regard to claims that the timing of creatine supplementation around exercise moderates gains in muscle creatine and exercise performance. This review discusses novel scientific evidence on the timing of creatine intake, the possible mechanisms that may be involved, and whether the timing of creatine supplementation around exercise is truly a real concern.

Effect Vladimir Janda Balance Training on Postural Sway and Leg Muscle Strength

Background: The majority of people who work as tea plantation pickers are powerful. They carry heavy loads of tea on their backs while the roads are quite dangerous and sometimes cause problems. A balance training program has proven to reduce postural sway, increasing leg muscle strength and improving balance strategies. Objective:The aim of this study was to determine the effect of  Vladimir Janda balance training methods with an external load on postural sway and leg muscle strength of tea pickers. Methods: The study design used was quasi-experimental with a randomized control group pretest-posttest design. Subjects were tea pickers consisting of a productive age group of 15 people and 15 people as a control treatment group. The Vladimir Janda method balance exercises were conducted over five weeks consisting of 5 phases. Phase I-IV were carried out 5 times a week, while the V phase was done 3 times a week and each session lasted 15 minutes. Postural sway was measured with a posturometer. Leg muscle strength was measured by a back-leg dynamometer. The statistical tests used were Independent T-test and the Mann-Whitney test. Results:The statistical test for the control and treatment groups using the Mann-Whitney test showed p = 0.001, meaning no external load effects on postural sway. Independent t-test showed p = 0.000, meaning there are differences in the effect between the treatment and control groups after being given balance exercises to increase leg muscle strength. Logistic regression test results obtained the ROC value of 0.917, meaning the Vladimir Janda balance training can affect the postural sway and knee extensor muscle strength by 91.7%. Conclusion: The Vladimir Janda balance exercise method can reduce postural sway and increase the strength of knee extensor muscles and ankle flexor Dorsi muscles. External loads can affect the postural sway.

Acute changes in muscle thickness, edema, and blood flow are not different between low-load blood flow restriction and non-blood flow restriction

The purpose of the present study was to examine the acute changes in muscle swelling (as assessed by muscle thickness and echo intensity) and muscle blood flow associated with an acute bout of low-load blood flow restriction (LLBFR) and low-load non-blood flow restriction (LL) exercise. Twenty women (mean ± SD; 22 ± 2years) volunteered to perform an acute exercise bout that consisted of 75 (1 × 30, 3 × 15) isokinetic, reciprocal, concentric-only, submaximal (30% of peak torque), forearm flexion and extension muscle actions. Pretest, immediately after (posttest), and 5-min after (recovery) completing the 75 repetitions, muscle thickness and echo intensity were assessed from the biceps brachii and triceps brachii muscles and muscle blood flow was assessed from the brachial artery. There were no between group differences for any of the dependent variables, but there were significant simple and main effects for muscle and time. Biceps and triceps brachii muscle thickness increased from pretest (2.13 ± 0.39 cm and 1.88 ± 0.40 cm, respectively) to posttest (2.58 ± 0.49 cm and 2.17 ± 0.43 cm, respectively) for both muscles and remained elevated for the biceps brachii (2.53 ± 0.43 cm), but partially returned to pretest levels for the triceps brachii (2.06 ± 0.41 cm). Echo intensity and muscle blood flow increased from pretest (98.0 ± 13.6 Au and 94.5 ± 31.6 ml min^-1 , respectively) to posttest (109.2 ± 16.9 Au and 312.2 ± 106.5 ml min^-1 , respectively) and pretest to recovery (110.1 ± 18.3 Au and 206.7 ± 92.9 ml min^-1 , respectively) and remained elevated for echo intensity, but partially returned to pretest levels for muscle blood flow. The findings of the present study indicated that LLBFR and LL elicited comparable acute responses as a result of reciprocal, concentric-only, forearm flexion and extension muscle actions.

Number of Repetitions Performed Before and After Reaching Velocity Loss Thresholds: First Repetition Versus Fastest Repetition-Mean Velocity Versus Peak Velocity

PURPOSE

To explore the effect of several methodological factors on the number of repetitions performed before and after reaching certain velocity loss thresholds (VLTs).

METHOD

Fifteen resistance-trained men (bench press 1-repetition maximum = 1.25 [0.16] kg·kg-1) performed with maximum intent a total of 182 sets (77 short sets [≤12 repetitions] and 105 long sets [>12 repetitions]) leading to failure during the Smith machine bench press exercise. Fifteen percent, 30%, and 45% VLTs were calculated, considering 2 reference repetitions (first and fastest repetitions) and 2 velocity variables (mean velocity [MV] and peak velocity [PV]).

RESULTS

The number of repetitions performed before reaching all VLTs were affected by the reference repetition and velocity variable (P ≤ .001). The fastest MV and PV during the short sets (75.3%) and PV during the long sets (72.4%) were predominantly observed during the first repetition, while the fastest MV during long sets was almost equally distributed between the first (37.1%) and second repetition (40.0%). Failure occurred before reaching the VLTs more frequently using PV (4, 8, and 33 occasions for 15%, 30%, and 45% VLTs, respectively) than MV (only 1 occasion for the 45% VLT). The participants rarely produced a velocity output above a VLT once this threshold was exceeded for the first time (≈10% and 30% of occasions during the short and long sets, respectively).

CONCLUSIONS

The reference repetition and velocity variable are important factors to consider when implementing VLTs during resistance training. The fastest repetition (instead of the first repetition) and MV (instead of PV) are recommended.

Unilateral, bilateral, and alternating muscle actions elicit similar muscular responses during low load blood flow restriction exercise

PURPOSE

Compare acute muscular responses to unilateral, bilateral, and alternating blood flow restriction (BFR) exercise.

METHODS

Maximal strength was tested on visit one. On visits 2-4, 2-10 days apart, 19 participants completed 4 sets of knee extensions (30% one-repetition maximum) with BFR (40% arterial occlusion pressure) to momentary failure (inability to lift load) using each muscle action (counterbalanced order). Ultrasound muscle thickness was measured at 60% and 70% of the anterior thigh before (Pre), immediately (Post-0), and 5 min (Post-5) after exercise. Surface electromyography and tissue deoxygenation were measured throughout. Results, presented as means, were analyzed with a three-way (sex by time by condition) Bayesian RMANOVA.

RESULTS

There was a time by sex interaction (BF_inclusion: 5.489) for left leg 60% muscle thickness (cm). However, changes from Pre to Post-0 (males: 0.39 vs females: 0.26; BF₁₀: 0.839), Post-0 to Post-5 (males: - 0.05 vs females: - 0.06; BF₁₀: 0.456), and Pre to Post-5 (males: 0.34 vs females: 0.20; BF₁₀: 0.935) did not differ across sex. For electromyography (%MVC), there was a sex by condition interaction (BF_inclusion: 550.472) with alternating having higher muscle excitation for females (16) than males (9; BF₁₀: 5.097). Tissue deoxygenation (e.g. channel 1, µM) increased more for males (sets 1: 11.17; 2: 2.91; 3: 3.69; 4: 3.38) than females (sets 1: 4.49; 2: 0.24; 3: - 0.10; 4: - 0.06) from beginning to end of sets (all BF_inclusion ≥ 4.295e + 7). For repetitions, there was an interaction (BF_inclusion: 17.533), with alternating completing more than bilateral and unilateral for set one (100; 56; 50, respectively) and two (34; 16; 18, respectively).

CONCLUSION

Alternating, bilateral, and unilateral BFR exercise elicit similar acute muscular responses.

Resistance Training Load Effects on Muscle Hypertrophy and Strength Gain: Systematic Review and Network Meta-analysis

PURPOSE

This study aimed to analyze the effect of resistance training (RT) performed until volitional failure with low, moderate, and high loads on muscle hypertrophy and muscle strength in healthy adults and to assess the possible participant-, design-, and training-related covariates that may affect the adaptations.

METHODS

Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science databases were searched. Including only studies that performed sets to volitional failure, the effects of low- (>15 repetitions maximum (RM)), moderate- (9-15 RM), and high-load (≤8 RM) RTs were examined in healthy adults. Network meta-analysis was undertaken to calculate the standardized mean difference (SMD) between RT loads in overall and subgroup analyses involving studies deemed of high quality. Associations between participant-, design-, and training-related covariates with SMD were assessed by univariate and multivariate network meta-regression analyses.

RESULTS

Twenty-eight studies involving 747 healthy adults were included. Although no differences in muscle hypertrophy between RT loads were found in overall (P = 0.113-0.469) or subgroup analysis (P = 0.871-0.995), greater effects were observed in untrained participants (P = 0.033) and participants with some training background who undertook more RT sessions (P = 0.031-0.045). Muscle strength improvement was superior for both high-load and moderate-load compared with low-load RT in overall and subgroup analysis (SMD, 0.60-0.63 and 0.34-0.35, respectively; P < 0.001-0.003), with a nonsignificant but superior effect for high compared with moderate load (SMD, 0.26-0.28, P = 0.068).

CONCLUSIONS

Although muscle hypertrophy improvements seem to be load independent, increases in muscle strength are superior in high-load RT programs. Untrained participants exhibit greater muscle hypertrophy, whereas undertaking more RT sessions provides superior gains in those with previous training experience.

Resistance Training Performed to Failure or Not to Failure Results in Similar Total Volume, but With Different Fatigue and Discomfort Levels

ABSTRACT

Santos, WDNd, Vieira, CA, Bottaro, M, Nunes, VA, Ramirez-Campillo, R, Steele, J, Fisher, JP, and Gentil, P. Resistance training performed to failure or not to failure results in similar total volume, but with different fatigue and discomfort levels. J Strength Cond Res 35(5): 1372-1379, 2021-The purpose of this study was to compare the acute response to 4 sets of high velocity parallel squats performed to momentary failure (MF) or not to momentary failure (NF). Twelve women (24.93 ± 5.04 years) performed MF and NF protocols, in a randomized order with 2-3 interday rest. The protocol involved 4 sets of parallel squats executed at high velocity at 10RM load, with 2 minutes of rest interval between sets. During the NF protocol, the sets were interrupted when the subject lost more than 20% of mean propulsive velocity. The analysis involved the number of repetitions performed per set, total number of repetitions, movement velocity loss, power output loss, rating of perceived exertion (RPE), rating of perceived discomfort (RPD), and session rating of perceived exertion (sRPE). Compared with NF, MF resulted in a higher number of repetitions in the first set (11.58 ± 1.83 vs. 7.58 ± 1.72, p < 0.05), but a lower in the last set (3.58 ± 1.08 vs. 5.41 ± 1.08, p < 0.05). Total number of repetitions was similar between the protocols (MF 26.25 ± 3.47 vs. NF 24.5 ± 3.65, p > 0.05). In both protocols, there were significant decreases in maximum and mean movement velocity loss and power output loss, but higher decreases were observed in MF than NF (p < 0.05). Values for RPE, sRPE, and RPD were higher during MF than NF (p < 0.05). Controlling the movement velocity in NF protocol enabled performance of a similar total volume of repetitions with lower movement velocity and power output losses, RPE, sRPE, and RPD than during an MF protocol.

Equating Resistance-Training Volume Between Programs Focused on Muscle Hypertrophy

Calculating resistance-training volume in programs focused on muscle hypertrophy is an attempt to quantify the external workload carried out, then to estimate the dose of stimulus imposed on targeted muscles. The volume is usually expressed in some variables that directly affected the total training work, such as the number of sets, repetitions, and volume-load. These variables are used to try to quantify the training work easily, for the subsequent organization and prescription of training programs. One of the main uses of measures of volume quantification is seen in studies in which the purpose is to compare the effects of different training protocols on muscle growth in a volume-equated format. However, it seems that not all measures of volume are always appropriate for equating training protocols. In the current paper, it is discussed what training volume is and the potentials and shortcomings of each one of the most common ways to equate it between groups depending on the independent variable to be compared (e.g., weekly frequency, intensity of load, and advanced techniques).

Acute exercise and cognition: A review with testable questions for future research into cognitive enhancement with blood flow restriction

Blood flow restriction, in combination with low load/intensity exercise, has consistently been shown to increase both muscle size and strength. In contrast, the effects of blood flow restricted exercise on cognition have not been well studied. Therefore, the purpose of this paper is 1) to review the currently available literature investigating the impact of blood flow restricted exercise on cognition and 2) to provide some hypotheses for how blood flow restriction might provide an additive stimulus for augmenting specific cognitive domains above exercise alone. Given the lack of research in this area, the effects of blood flow restricted exercise on cognition are still unclear. We hypothesize that blood flow restricted exercise could potentially enhance several cognitive domains (such as attention, executive functioning, and memory) through increases in lactate production, catecholamine concentration, and PGC-1α expression. We review work that suggests that blood flow restriction is not only a beneficial strategy to improve musculoskeletal function but could also be a favorable method for enhancing multiple domains of cognition. Nonetheless, it must be emphasized this is a hypothesis that currently has only minimal experimental support, and further investigations in the future are necessary to test the hypothesis.

Self-Selected Resistance Exercise Load: Implications for Research and Prescription

ABSTRACT

Barbosa-Netto, S, d'Acelino-e-Porto, OS, and Almeida, MB. Self-selected resistance exercise load: implications for research and prescription. J Strength Cond Res 35(2S): S166-S172, 2021-Resistance training has been widely used for maintaining or improving the quality of life and sports performance. It is not clear, however, whether the load commonly used in these exercises is equivalent to the number of repetitions determined for execution, that is, the level of effort applied to the self-selected load. Ergo, the aim of this study was to identify the number of maximum repetitions that strength training practitioners can perform with the load commonly used (self-selected) to perform 10 repetitions in their training routines. The sample consisted of 160 healthy trained men (25.7 ± 4.5 years, 81.2 ± 10.4 kg, 177.9 ± 6.2 cm). Subjects answered the question "What weight do you usually lift for 10 repetitions on free-weight bench press exercise?" The answer was considered the self-selected 10 repetitions load (S10RL). After a brief warm-up, each individual was instructed to perform as many repetitions as possible at S10RL (repetition maximum [RMS10RL]) at a single bout of free-weight bench press. The RMS10RL was analyzed with the single sample t test, adopting the reference value of 10 repetitions. Individuals performed 16 ± 5RMS10RL (median = 15), which represent a statistical difference for the 10-repetition reference value (p < 0.001). The most prevalent RMS10RL range was from 13 to 15 repetitions (31%), and only 22% performed between 10 and 12 repetitions. It was concluded that most individuals can perform a number of repetitions well above the 10 repetitions predicted for the selected load. Therefore, the training routines are not compatible with maximum effort.

Are We Exploring the Potential Role of Specialized Techniques in Muscle Hypertrophy?

Specialized resistance training techniques (e.g., drop-set, rest-pause) are commonly used by well-trained subjects for maximizing muscle hypertrophy. Most of these techniques were designed to allow a greater training volume (i.e., total repetitions×load), due to the supposition that it elicits greater muscle mass gains. However, many studies that compared the traditional resistance training configuration with specialized techniques seek to equalize the volume between groups, making it difficult to determine the inherent hypertrophic potential of these advanced strategies, as well as, this equalization restricts part of the practical extrapolation on these findings. In this scenario, the objectives of this manuscript were 1) to present the nuance of the evidence that deals with the effectiveness of these specialized resistance training techniques and - primarily - to 2) propose possible ways to explore the hypertrophic potential of such strategies with greater ecological validity without losing the methodological rigor of controlling possible intervening variables; and thus, contributing to increasing the applicability of the findings and improving the effectiveness of hypertrophy-oriented resistance training programs.

"Just One More Rep!" - Ability to Predict Proximity to Task Failure in Resistance Trained Persons

In resistance training, the use of predicting proximity to momentary task failure (MF, i.e., maximum effort), and repetitions in reserve scales specifically, is a growing approach to monitoring and controlling effort. However, its validity is reliant upon accuracy in the ability to predict MF which may be affected by congruence of the perception of effort compared with the actual effort required. The present study examined participants with at least 1 year of resistance training experience predicting their proximity to MF in two different experiments using a deception design. Within each experiment participants performed four trials of knee extensions with single sets (i.e., bouts of repetitions) to their self-determined repetition maximum (sdRM; when they predicted they could not complete the next repetition if attempted and thus would reach MF if they did) and MF (i.e., where despite attempting to do so they could not complete the current repetition). For the first experiment (n = 14) participants used loads equal to 70% of a one repetition maximum (1RM; i.e., the heaviest load that could be lifted for a single repetition) performed in a separate baseline session. Aiming to minimize participants between day variability in repetition performances, in the second separate experiment (n = 24) they used loads equal to 70% of their daily isometric maximum voluntary contraction (MVC). Results suggested that participants typically under predicted the number of repetitions they could perform to MF with a meta-analytic estimate across experiments of 2.0 [95%CIs 0.0 to 4.0]. Participants with at least 1 year of resistance training experience are likely not adequately accurate at gauging effort in submaximal conditions. This suggests that perceptions of effort during resistance training task performance may not be congruent with the actual effort required. This has implications for controlling, programming, and manipulating the actual effort in resistance training and potentially on the magnitude of desired adaptations such as improvements in muscular hypertrophy and strength.

Velocity Loss Thresholds Reliably Control Kinetic and Kinematic Outputs during Free Weight Resistance Training

Exercise velocity and relative velocity loss thresholds (VLTs) are commonly used in velocity-based resistance training. This study aims to quantify the between-day reliability of 10%, 20%, and 30% VLTs on kinetic and kinematic outputs, changes in external load, and repetition characteristics in well-trained athletes. Using a repeated, counter-balanced crossover design, twelve semi-professional athletes completed five sets of the back squat with an external load corresponding to a mean concentric velocity of ~0.70 m·s^-1 and a VLT applied. The testing sessions were repeated after four weeks of unstructured training to assess the long-term reliability of each VLT. A coefficient of variation (CV) <10% was used to classify outputs as reliable. Kinetic and kinematic outputs and external load were largely reliable, with only peak power during sets 2-5 within the 10% VLT condition demonstrating a CV >10% (CV: 11.14-14.92%). Alternatively, the repetitions completed within each set showed large variation (CV: 18.92-67.49%). These findings demonstrate that by utilizing VLTs, kinetic and kinematic outputs can be prescribed and replicated across training mesocycles. Thus, for practitioners wishing to reliably control the kinetic and kinematic stimulus that is being applied to their athletes, it is advised that a velocity-based approach is used.

Placing Greater Torque at Shorter or Longer Muscle Lengths? Effects of Cable vs. Barbell Preacher Curl Training on Muscular Strength and Hypertrophy in Young Adults

Muscular strength and hypertrophy following resistance training may be obtained in different degrees depending on the approach performed. This study was designed to compare the responses of the biceps brachii to two preacher curl exercises, one performed on a cable-pulley system (CAB; in which a greater torque was applied during the exercise when elbows were flexed and biceps shortened) and one performed with a barbell (BAR; in which greater torque was applied when the elbows were extended and biceps stretched). Thirty-five young adults (CAB: 13 men, 5 women; BAR: 12 men, 5 women; age = 24 ± 5 years) performed a resistance training program three times per week for 10 weeks, with preacher curl exercises performed in three sets of 8–12 repetitions. Outcomes measured included elbow flexion peak isokinetic torque at angles of 20°, 60°, and 100° (considering 0° as elbow extended), and biceps brachii thickness (B-mode ultrasound). Following the training period, there were significant increases for both groups in elbow flexion peak torque at the 20° (CAB: 30%; BAR = 39%; p = 0.046), 60° (CAB: 27%; BAR = 32%; p = 0.874), and 100° (CAB: 17%; BAR = 19%; p = 0.728), and biceps brachii thickness (CAB: 7%; BAR = 8%; p = 0.346). In conclusion, gains in muscular strength were greater for BAR only at longer muscle length, whereas hypertrophy was similar regardless of whether torque emphasis was carried out in the final (CAB) or initial (BAR) degrees of the range of motion of the preacher curl in young adults.

Can Hip Joint Position affect Quadriceps Muscle Responses during Knee Extension Exercise?

This study investigated the acute effects of seated and supine knee extension exercise on muscle swelling, torque, and work output. Twelve resistance-trained men performed two isokinetic concentric-only knee-extension training protocols at different hip positions in a counter-balanced order. They completed the knee extension exercise in the seated (hip angle at 85°) and supine (hip angle at 180°) positions. The torque and work output were assessed during each set. Moreover, muscle thickness of the middle and proximal vastus lateralis and rectus femoris were evaluated before and after each protocol and used as an indicator of muscle swelling. Middle rectus femoris and proximal vastus lateralis thickness increased significantly (p=0.01) with no difference between exercise variations. However, the middle vastus lateralis thickness increased (p=0.01) only after the seated knee extension exercise (~7%). Knee extensors' peak torque and work output were approximately 8% higher (p=0.04) in the seated when compared to the supine hip position. There was a similar decrease in torque and work output throughout both protocols (p=0.98). In conclusion, seated knee extension exercises produced greater torque, work output, and muscle swelling in the vastus lateralis when compared to the supine knee extension exercise.

Cluster-sets resistance training induce similar functional and strength improvements than the traditional method in postmenopausal and elderly women

OBJECTIVE

The aim of this study was to compare the effects of 12 weeks of traditional resistance training (TRT) or resistance training using Cluster-set (CS) on functional performance and physical fitness of postmenopausal and elderly women.

METHODS

Participants (61.1 ± 4.9 years, body mass 64.5 ± 1.8 kg, height 155.7 ± 4.7 cm) were randomized to TRT (n = 35) or CS (n = 31). Anthropometric measures, muscle strength and power, gait speed, core stability, flexibility, and functional performance tests were performed before and after 12 weeks of training. The difference between protocols was the structure of rest intervals. The TRT group performed 120 s of rest between sets of 8 repetitions, while the CS performed 30 s of rest after every 2 repetitions. Two-way ANOVA with repeated measures was applied for each variable and, when needed, the Bonferroni post hoc was used. Statistical significance was set at p < 0.05.

RESULTS

No group by time interaction was found for any variable. Regarding between-moment comparisons, there were significant improvements for 1 repetition maximum (RM) bench press (F = 104.6; η_p² = 0.62; p < 0.001), 1RM leg press (F = 74.6; η_p² = 0.53; p < 0.001), medicine ball throw (F = 64.0; η_p² = 0.26; p < 0.001), standing long jump (F = 27.6; η_p² = 0.30; p < 0.001), countermovement jump (F = 17.4; η_p² = 0.21; p < 0.001), squat jump (F = 23.2; η_p² = 0.26; p < 0.001), plank time (F = 31.6; η_p² = 0.33; p < 0.001), 6 m walking test (F = 18.0; η_p² = 0.22; p < 0.001), sit-to-stand test (F = 20.4; η_p² = 0.24; p < 0.001), sit and reach test (F = 56.8; η_p² = 0.47; p < 0.001) and 2 kg elbow curls (F = 15.9; η_p² = 0.19; p < 0.001).

CONCLUSION

Considering that both CS and TRT methods were equally effective to improve the physical fitness and functionality of elderly women, the decision of which protocol to use should be based on individual preferences and practical aspects.

Eccentric, but not concentric blood flow restriction resistance training increases muscle strength in the untrained limb

OBJECTIVES

Little is known regarding the variables or mechanisms mediating cross-education as a result of resistance training. Therefore, the purpose of the present study was to examine the effects of low-load eccentric-only blood flow restriction (Ecc-BFR) and low-load concentric-only BFR (Con-BFR) on indices of cross-education.

DESIGN

Thirty-six women were randomly assigned to 4-wks of unilateral resistance training with Ecc-BFR (n = 12), Con-BFR (n = 12) or control (no intervention, n = 12) group. Eccentric peak torque, concentric peak torque, maximal voluntary isometric contraction torque, muscle thickness, and muscle activation were assessed from the contralateral, untrained arm.

RESULTS

Muscle strength (collapsed across mode) increased from 0-wk to 2-wks (4.9%) and 4-wks (13.0%) for Ecc-BFR only. There were increases in muscle activation (collapsed across mode and group) regardless of training modality, but there were no changes in muscle size for any of the conditions.

CONCLUSIONS

The findings of the present study indicated that low-load Ecc-BFR increased muscle strength. The increases in muscle strength as a result of Ecc-BFR were not mode-specific. Thus, low-load Ecc-BFR provides a unique alternative to maintain muscle function in an untrained limb that may have application during limb immobilization and rehabilitation practices.

Are cluster sets an effective method to induce muscular hypertrophy in response to resistance training?

ABSTRACT There are a plethora of studies that have analyzed the effects of different resistance training methods on muscle hypertrophy. Recent studies have pointed out some potential advantage of training using cluster sets (CS) compared with traditional sets. It is still unclear whether CS are an effective method. The objective of this review was to investigate and discuss the current knowledge about the effect of CS on muscle hypertrophy. Four studies investigating the effect of CS on muscle hypertrophy were found. These studies demonstrated that CS induced similar or lower muscle hypertrophy than traditional sets. Thus, CS may lead to muscle hypertrophy, but did not provide a superior stimulus when compared to traditional sets of equated load.

Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men

Purpose

The purpose of this study was to evaluate muscular adaptations between low-, moderate-, and high-volume resistance training protocols in resistance-trained men.

Methods

Thirty-four healthy resistance-trained men were randomly assigned to one of three experimental groups: a low-volume group performing one set per exercise per training session (n = 11), a moderate-volume group performing three sets per exercise per training session (n = 12), or a high-volume group performing five sets per exercise per training session (n = 11). Training for all routines consisted of three weekly sessions performed on nonconsecutive days for 8 wk. Muscular strength was evaluated with one repetition maximum (RM) testing for the squat and bench press. Upper-body muscle endurance was evaluated using 50% of subjects bench press 1RM performed to momentary failure. Muscle hypertrophy was evaluated using B-mode ultrasonography for the elbow flexors, elbow extensors, mid-thigh, and lateral thigh.

Results

Results showed significant preintervention to postintervention increases in strength and endurance in all groups, with no significant between-group differences. Alternatively, while all groups increased muscle size in most of the measured sites from preintervention to postintervention, significant increases favoring the higher-volume conditions were seen for the elbow flexors, mid-thigh, and lateral thigh.

Conclusions

Marked increases in strength and endurance can be attained by resistance-trained individuals with just three 13-min weekly sessions over an 8-wk period, and these gains are similar to that achieved with a substantially greater time commitment. Alternatively, muscle hypertrophy follows a dose–response relationship, with increasingly greater gains achieved with higher training volumes.

Functional and/or structural brain changes in response to resistance exercises and resistance training lead to cognitive improvements - a systematic review

BACKGROUND

During the aging process, physical capabilities (e.g., muscular strength) and cognitive functions (e.g., memory) gradually decrease. Regarding cognitive functions, substantial functional (e.g., compensatory brain activity) and structural changes (e.g., shrinking of the hippocampus) in the brain cause this decline. Notably, growing evidence points towards a relationship between cognition and measures of muscular strength and muscle mass. Based on this emerging evidence, resistance exercises and/or resistance training, which contributes to the preservation and augmentation of muscular strength and muscle mass, may trigger beneficial neurobiological processes and could be crucial for healthy aging that includes preservation of the brain and cognition. Compared with the multitude of studies that have investigated the influence of endurance exercises and/or endurance training on cognitive performance and brain structure, considerably less work has focused on the effects of resistance exercises and/or resistance training. While the available evidence regarding resistance exercise-induced changes in cognitive functions is pooled, the underlying neurobiological processes, such as functional and structural brain changes, have yet to be summarized. Hence, the purpose of this systematic review is to provide an overview of resistance exercise-induced functional and/or structural brain changes that are related to cognitive functions.

METHODS AND RESULTS

A systematic literature search was conducted by two independent researchers across six electronic databases; 5957 records were returned, of which 18 were considered relevant and were analyzed.

SHORT CONCLUSION

Based on our analyses, resistance exercises and resistance training evoked substantial functional brain changes, especially in the frontal lobe, which were accompanied by improvements in executive functions. Furthermore, resistance training led to lower white matter atrophy and smaller white matter lesion volumes. However, based on the relatively small number of studies available, the findings should be interpreted cautiously. Hence, future studies are required to investigate the underlying neurobiological mechanisms and to verify whether the positive findings can be confirmed and transferred to other needy cohorts, such as older adults with dementia, sarcopenia and/or dynapenia.

Blood flow restriction augments the skeletal muscle response during very low-load resistance exercise to volitional failure

The purpose of this study was to compare the acute muscular response with resistance exercise between the following conditions [labeled (% one-repetition maximum/% arterial occlusion pressure)]: high-load (70/0), very low-load (15/0), very low-load with moderate (15/40), and high (15/80) blood flow restriction pressures. Twenty-three participants completed four sets of unilateral knee extension to failure (up to 90 repetitions) with each condition, one condition per leg, each day. Muscle thickness and maximal voluntary contraction (MVC) were measured before (Pre), immediately after (Post-0), and 15 min after (Post-15) exercise and electromyography (EMG) amplitude during exercise. Pre to Post-0 muscle thickness changes in cm [95% CI] were greater with 15/40 [0.57 (0.41, 0.73)] and 15/80 [0.49 (0.35, 0.62)] compared to 70/0 [0.33 (0.25, 0.40)]. Pre to Post-0 MVC changes in Nm [95% CI] were higher with 15/40 [-127.0 (-162.1, -91.9)] and 15/80 [-133.6 (-162.8, -104.4)] compared to 70/0 [-48.4 (-70.1, -26.6)] and 15/0 [-98.4 (-121.9, -74.9)], which were also different. Over the first three repetitions, EMG increased across sets, whereas in the last three repetitions it did not. EMG was also different between conditions and was generally greater during 70/0. Repetitions decreased across sets reaching the lowest for 70/0, and for very low loads decreased with increased pressure. In trained participants exercising to failure, lower load and the application of restriction pressure augment changes in muscle thickness and torque. The EMG amplitude was augmented by load. Training studies should compare these conditions, as the results herein suggest some muscular adaptations may differ.

The impact of cuff width and biological sex on cuff preference and the perceived discomfort to blood-flow-restricted arm exercise

OBJECTIVE

To investigate the influence of cuff width, sex, and applied pressure on the perceived discomfort associated with blood flow restriction at rest and following exercise.

APPROACH

Experiment 1 (n  =  96) consisted of four sets of biceps exercise to failure with a narrow and wide cuff inflated to the same relative pressure. Experiment 2 (n  =  87) compared two wide cuffs, one of which was inflated to a relative pressure obtained from a narrow cuff. Experiment 3 (n  =  50) compared the discomfort of wide and narrow cuffs at rest. Effects are presented as median δ (95% credible interval).

MAIN RESULTS

There was no sex effect for any variable of interest. In Experiment 1, the narrow cuff resulted in less discomfort than the wide cuff (39.3 versus 42.5; median δ  -0.388 (-0.670, -0.109)). Participants also rated the narrow cuff as more preferable. Experiment 2 found that a wide cuff inflated to a narrow cuffs pressure resulted in greater discomfort than a wide cuff (44 versus 40.9; median δ: 0.420 (0.118, 0.716)). Experiment 3 found no difference between cuff widths.

SIGNIFICANCE

Blood flow restricted exercise with a narrow cuff results in less discomfort than a wider cuff inflated to the same relative pressure. This effect is not observed at rest and suggests that the wide cuff produces a differential environment compared to a narrow cuff when combined with exercise. Additionally, applying a pressure meant for a narrow cuff to a wide cuff augments the applied pressure and subsequent discomfort to blood flow restricted exercise.

Blood Flow Restriction Training in Rehabilitation: A Useful Adjunct or Lucy's Latest Trick?

New approaches that promise more for less rarely pan out despite the hopes of physical therapists. In this Viewpoint, the author discusses blood flow restriction training, an intervention claiming that some low-intensity exercise performed while wearing a blood pressure cuff will result in strength gains, improved performance, shorter postexercise recovery, and pain reduction. J Orthop Sports Phys Ther 2019;49(5):294-298. doi:10.2519/jospt.2019.0608.

Shorter But More Frequent Rest Periods: No Effect on Velocity and Power Compared to Traditional Sets Not Performed to Failure

Performing traditional sets to failure is fatiguing, but redistributing total rest time to create short frequent sets lessens the fatigue. Since performing traditional sets to failure is not always warranted, we compared the effects of not-to-failure traditional sets and rest redistribution during free-weight back squats in twenty-six strength-trained men (28 ± 5.44 y; 84.6 ± 10.5 kg, 1RM-to-body-mass ratio of 1.82 ± 0.33). They performed three sets of ten repetitions with 4 min inter-set rest (TS) and five sets of six repetitions with 2 min inter-set rest (RR6) at 70% of one repetition maximum. Mean velocity (p > 0.05; d = 0.10 (-0.35, 0.56)) and mean power (p > 0.05; d = 0.19 (-0.27, 0.64)) were not different between protocols, but the rating of perceived exertion (RPE) was less during RR6 (p < 0.05; d = 0.93 (0.44, 1.40)). Also, mean velocity and power output decreased (RR6: 14.10% and 10.95%; TS: 17.10% and 15.85%, respectively) from the first repetition to the last, but the percentage decrease was similar (velocity: p > 0.05; d = 0.16 (0.30, 0.62); power: p > 0.05; d = 0.22 (-0.24, 0.68)). These data suggest that traditional sets and rest redistribution maintain velocity and power output to a similar degree when traditional sets are not performed to failure. However, rest redistribution might be advantageous as RR6 displayed a lower RPE.