The effects of different doses of caffeine on maximal strength and strength-endurance in women habituated to caffeine

Purpose

The main goal of this study was to assess the acute effects of 3 and 6 mg of caffeine intake per kg of body mass (b.m.) on maximal strength and strength-endurance in women habituated to caffeine.

Methods

Twenty-one healthy resistance-trained female students (23.0 ± 0.9 years, body mass: 59.0 ± 6.6 kg), with a daily caffeine intake of 5.8 ± 2.6 mg/kg/b.m. participated in a randomized, crossover, double-blind design. Each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 3 mg/kg/b.m. (CAF-3) and 6 mg/kg/b.m. (CAF-6) of caffeine. In each experimental session, the participants underwent a 1RM test and a strength-endurance test at 50 %1RM in the bench press exercise. Maximal load was measured in the 1RM test and the time under tension, number of preformed repetitions, power output and bar velocity were registered in the strength-endurance test.

Results

The one-way ANOVA showed a main effect of caffeine on 1RM bench press performance (F = 14.74; p < 0.01). In comparison to the PLAC (40.48 ± 9.21 kg), CAF-3 (41.68 ± 8.98 kg; p = 0.01) and CAF-6 (42.98 ± 8.79 kg; p < 0.01) increased 1RM bench press test results. There was also a significant increase in 1RM for CAF-6 when compared to CAF-3 (p < 0.01). There was a main effect of caffeine on time under tension during the strength-endurance test (F = 13.09; p < 0.01). In comparison to the PLAC (53.52 ± 11.44 s), CAF-6 (61.76 ± 15.39 s; p < 0.01) significantly increased the time under tension during the maximal strength-endurance test.

Conclusion

An acute dose of 3-to-6 mg/kg/b.m. of caffeine improves maximum strength. However, these doses of caffeine had minimal ergogenic effect on strength-endurance performance in women habituated to caffeine.

Morning fatigue and structured exercise interact to affect non-exercise physical activity of fit and healthy older adults

Background

Exercise training is crucial for maintaining physical and mental health in aging populations. However, as people participate in structured exercise training, they tend to behaviorally compensate by decreasing their non-exercise physical activity, thus potentially blunting the benefits of the training program. Furthermore, physical activity of older adults is substantially influenced by physical feelings such as fatigue. Nevertheless, how older people react to day-to-day fluctuations of fatigue and whether fatigue plays a role in non-exercise physical activity compensation is not known. Thus, the purpose of this study was twofold: (1) To explore whether the volume and intensity of habitual physical activity in older adults were affected by morning fatigue. (2) To investigate the effect of attending power and resistance exercise sessions on the levels of non-exercise physical activity later that day and the following day.

Methods

Twenty-eight older adults wore an accelerometer during a 4-week low-volume, low-intensity resistance and power training program with three exercise sessions per week and for 3 weeks preceding and 1 week following the program. During the same period, the participants were prompted every morning, using text messages, to rate their momentary fatigue on a scale from 0 to 10.

Results

Greater morning fatigue was associated with lower volume (p = 0.002) and intensity (p = 0.017) of daily physical activity. Specifically, one point greater on the fatigue scale was associated with 3.2 min (SE 1.0) less moderate-to-vigorous physical activity. Furthermore, attending an exercise session was associated with less moderate-to-vigorous physical activity later that day by 3.7 min (SE 1.9, p = 0.049) compared to days without an exercise session. During the next day, the volume of physical activity was greater, but only in participants with a body mass index up to 23 (p = 0.008).

Conclusions

Following low-volume exercise sessions, fit and healthy older adults decreased their non-exercise physical activity later that day, but this compensation did not carry over into the next day. As momentary morning fatigue negatively affects daily physical activity, we suggest that the state level of fatigue should be monitored during intensive exercise programs, especially in less fit older adults with increased fatigability.

The Effects of Set Structure Manipulation on Chronic Adaptations to Resistance Training: A Systematic Review and Meta-Analysis

BACKGROUND

The acute effects of resistance training (RT) set structure alteration are well established; however, less is known about their effects on chronic training adaptations.

OBJECTIVE

The aim of this systematic review and meta-analysis was to synthesise the available evidence on the effectiveness of traditional (TS), cluster (CS) and rest redistribution (RR) set structures in promoting chronic RT adaptations, and provide an overview of the factors which might differentially influence the magnitude of specific training adaptations between set structure types.

METHODS

This review was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines encompassing the literature search of five databases. Studies in English that compared muscular strength, endurance, and/or hypertrophy adaptations, as well as vertical jump performance, velocity and power at submaximal loads and shifts in the slopes of force-velocity profiles between TS and CS or RR set structures (i.e., alternative set structures) were included. Risk of bias assessment was performed using a modified Cochrane Collaboration's tool for assessing risk of bias in randomised trials. Random-effects meta-analyses and meta-regressions were performed where possible.

RESULTS

17 studies met the inclusion criteria, none had more than one risk of bias item assessed as high risk. Pooled results revealed that none of the set structures were more effective at inducing strength (standardised mean difference (SMD) = - 0.06) or hypertrophy (SMD = - 0.03). TS were more effective at improving muscular endurance compared to alternative set structures (SMD = - 0.38), whereas alternative set structures tended to be more effective for vertical jump performance gains (SMD = 0.13), but this effect was not statistically significant (p = 0.190). Greater velocity and power outputs at submaximal loads (SMD = 0.18) were observed when using alternative set structures compared to TS. In addition, alternative set structures promoted greater shifts of the slope of force-velocity profiles towards more velocity dominant profiles compared to TS (SMD = 0.28). Sub-group analyses controlling for each alternative set structure independently showed mixed results likely caused by the relatively small number of studies available for some outcomes.

CONCLUSION

Modifying TS to an alternative set structure (CS or RR) has a negligible impact on strength and hypertrophy. Using CS and RR can lead to greater vertical jump performance, velocity and power at submaximal loads and shifts to more velocity dominant force-velocity profiles compared to training using TS. However, TS may provide more favourable effects on muscle endurance when compared to CS and RR. These findings demonstrate that altering TS to alternative set structures may influence the magnitude of specific muscular adaptations indicating set structure manipulation is an important consideration for RT program design.

PROTOCOL REGISTRATION

The original protocol was prospectively registered (CRD42019138954) with the PROSPERO (International Prospective Register of Systematic Reviews).

The Influence of Movement Tempo on Acute Neuromuscular, Hormonal, and Mechanical Responses to Resistance Exercise-A Mini Review

Wilk, M, Tufano, JJ, and Zajac, A. The influence of movement tempo on acute neuromuscular, hormonal, and mechanical responses to resistance exercise-a mini review. J Strength Cond Res 34(8): 2369-2383, 2020-Resistance training studies mainly analyze variables such as the type and order of exercise, intensity, number of sets, number of repetitions, and duration and frequency of rest periods. However, one variable that is often overlooked in resistance training research, as well as in practice, is premeditated movement tempo, which can influence a myriad of mechanical and physiological factors associated with training and adaptation. Specifically, this article provides an overview of the available scientific literature and describes how slower tempos negatively affect the 1-repetition maximum, the possible load to be used, and the number of repetitions performed with a given load, while also increasing the total time under tension, which can mediate acute cardiovascular and hormonal responses. As a result, coaches should consider testing maximal strength and the maximal number of repetitions that can be performed with each movement tempo that is to be used during training. Otherwise, programming resistance training using various movement tempos is more of a trial-and-error approach, rather than being evidence or practice based. Furthermore, practical applications are provided to show how movement tempo can be adjusted for a variety of case study-type scenarios.

Traditional 3- to 5-Minute Interset Rest Periods May Not Be Necessary When Performing Fewer Repetitions Per Set: Using Clean Pulls as an Example

Jukic, I and Tufano, JJ. Traditional 3- to 5-minute interset rest periods may not be necessary when performing fewer repetitions per set: Using clean pulls as an example. J Strength Cond Res XX(X): 000-000, 2020-Three to 5 minutes of interset rest is often recommended for power-based exercises, but those recommendations are largely based on performing many repetitions per set, which can induce fatigue and require such lengthy rest periods. If the number of repetitions per set is reduced before fatigue ensues, interset rest periods may also be reduced without sacrificing performance. Therefore, the purpose of this study was to investigate the effects of this notion on barbell velocity and power output over multiple sets of clean pulls using different loads in strength-trained men. Fifteen strength-trained men performed 3 extended sets of 6 clean pulls using 80% (EXT80), 100% (EXT100), and 120% (EXT120) of power clean 1 repetition maximum with 180 seconds of interset rest and 9 short sets of 2 using 80% (SHT80), 100% (SHT100), and 120% (SHT120) with 45 seconds of interset rest. Peak velocity was greater during short set protocol than extended set protocol (80%: 1.74 ± 0.16 vs. 1.68 ± 0.15 m/s; 100%: 1.47 ± 0.15 vs. 1.41 ± 0.12 m/s; 120%: 1.21 ± 0.13 vs. 1.16 ± 0.15 m/s; p < 0.05). Furthermore, peak power was greater during SHT100 (1874.6 ± 267.5 vs. 1732.3 ± 250.4 W; p < 0.05) and SHT120 (1777.8 ± 226.1 vs. 1,650.4 ± 249.1 W; p < 0.05) than EXT100 and EXT120, respectively. Therefore, reducing the number of repetitions per set may allow for interset rest periods to also be reduced while better maintaining performance. However, the extent to which rest periods can be shortened warrants further investigation as total rest time was equal in this study.

The Use of Lifting Straps Alters the Entire Load-Velocity Profile During the Deadlift Exercise

Jukic, I, García-Ramos, A, Malecek, J, Omcirk, D, and Tufano, JJ. The use of lifting straps alters the entire load-velocity profile during the deadlift exercise. J Strength Cond Res 34(12): 3331-3337, 2020-This study aimed to compare the one repetition maximum (1RM) and load-velocity (LV) profile between deadlifts performed with (DLw) and without (DLn) lifting straps. The full individual LV relationship of 20 men (age: 24.3 ± 2.4 years; body height: 180.6 ± 6.9 cm; body mass: 85.8 ± 8.0 kg) was randomly evaluated during 2 separate sessions for the DLw and DLn via an incremental loading test. One repetition maximum was greater (p < 0.001; g = 0.56, 95% confidence interval = [0.32, 0.79]) for DLw (177.0 ± 28.9 kg) compared with DLn (160.6 ± 26.0 kg). A highly linear relationship between mean velocity (MV) and %1RM was observed for both conditions (R > 0.95; SEE < 6.18 %1RM for pooled data and R > 0.98; SEE < 3.6 %1RM for individual data). However, MV associated with each %1RM was greater for DLn, and these differences were accentuated as the loading magnitude increased (g = 0.30-1.18). One repetition maximum was strongly associated between both conditions (r = 0.875 [0.71, 0.95]), whereas MV at 1RM (r = 0.21 [-0.25, 0.60]) was unrelated between conditions. The slope of the LV profiles (r = 0.845 [0.64, 0.94]) was correlated, but differed (g = 0.41 [0.16, 0.66]) between DLw and DLn, whereas the mean test velocity of all loads was unrelated (r = 0.270 [-0.20, 0.64]). An individual LV profile should be created for each athlete in the same condition that are going to be used in training to obtain a more precise estimation of the submaximal relative loads.

Impact of Rest-Redistribution on Fatigue During Maximal Eccentric Knee Extensions

Redistributing long inter-set rest intervals into shorter but more frequent rest intervals generally maintains concentric performance, possibly due to improved energy store maintenance. However, eccentric actions require less energy than concentric actions, meaning that shorter but more frequent sets may not affect eccentric actions to the same degree as concentric actions. Considering the increased popularity of eccentric exercise, the current study evaluated the effects of redistributing long inter-set rest periods into shorter but more frequent rest periods during eccentric only knee extensions. Eleven resistance-trained men performed 40 isokinetic unilateral knee extensions at 60°·s-1 with 285 s of total rest using traditional sets (TS; 4 sets of 10 with 95 s inter-set rest) and rest-redistribution (RR; 20 sets of 2 with 15 s inter-set rest). Before and during exercise, muscle oxygenation was measured via near-infrared spectroscopy, and rating of perceived exertion (RPE) was recorded after every 10th repetition. There were no differences between protocols for peak torque (RR, 241.58±47.20 N; TS, 231.64±48.87 N; p=0.396) or total work (RR, 215.26±41.47 J; TS, 209.71±36.02 J; p=0.601), but moderate to large effect sizes existed in later repetitions (6,8,10) with greater peak torque during RR (d=0.66-1.19). For the entire session, RR had moderate effects on RPE (RR, 5.73±1.42; TS, 6.09±1.30; p=0.307; d=0.53) and large effects on oxygen saturation (RR, 5857.4±310.0; TS, 6495.8±273.8; p=0.002, d=2.13). Therefore, RR may maintain peak torque or total work during eccentric exercise, improve oxygen utilization at the muscle, and reduce the perceived effort.

Assisted Jumping in Healthy Older Adults: Optimizing High-Velocity Training Prescription

Tufano, JJ, Vetrovsky, T, Stastny, P, Steffl, M, Malecek, J, and Omcirk, D. Assisted jumping in healthy older adults: optimizing high-velocity training prescription. J Strength Cond Res XX(X): 000-000, 2020-Because older adults benefit from power training, training strategies for athletes such as supramaximal velocity-assisted jumping could also be useful for older adults. However, optimizing-assisted exercise prescription in older adults remains uninvestigated. Therefore, the purpose of this study was to determine the effects of different bodyweight (BW) assistance levels on jumping force and velocity in healthy older adults. Twenty-three healthy older adults (67.6 ± 7.6 years, 167.0 ± 8.8 cm, 72.7 ± 14.3 kg, and 27.1 ± 6.9% body fat) performed 5 individual countermovement jumps at BW, 90, 80, 70, and 60% of BW. Jumps were performed on a force plate, which provided peak take-off force (TOF), flight time, and peak impact force. A linear position transducer measured peak concentric velocity (PV). The rating of perceived exertion (RPE) was also assessed after each condition. Take-off force was greater during BW than all other conditions, 90 and 80% were greater than 70 and 60%, but there were no differences between 80 and 90% or between 70 and 60%. The FT progressively increased at all assistance levels, and PV was faster for all assistance levels than BW, with no differences between assistance levels. Impact force was greater during BW than 80, 70, and 60% and was greater during 90% than 60%. The RPE was less than BW during all assistance conditions but was the least during 70%. Implementing assisted jumping between 70 and 80% of BW in older adults likely provides the ideal combination of force, velocity, and RPE.

Advances in accelerometry for cardiovascular patients: a systematic review with practical recommendations

Aims

Accelerometers are becoming increasingly commonplace for assessing physical activity; however, their use in patients with cardiovascular diseases is relatively substandard. We aimed to systematically review the methods used for collecting and processing accelerometer data in cardiology, using the example of heart failure, and to provide practical recommendations on how to improve objective physical activity assessment in patients with cardiovascular diseases by using accelerometers.

Methods and results

Four electronic databases were searched up to September 2019 for observational, interventional, and validation studies using accelerometers to assess physical activity in patients with heart failure. Study and population characteristics, details of accelerometry data collection and processing, and description of physical activity metrics were extracted from the eligible studies and synthesized. To assess the quality and completeness of accelerometer reporting, the studies were scored using 12 items on data collection and processing, such as the placement of accelerometer, days of data collected, and criteria for non‐wear of the accelerometer. In 60 eligible studies with 3500 patients (of those, 536 were heart failure with preserved ejection fraction patients), a wide variety of accelerometer brands (n = 27) and models (n = 46) were used, with Actigraph being the most frequent (n = 12), followed by Fitbit (n = 5). The accelerometer was usually worn on the hip (n = 32), and the most prevalent wear period was 7 days (n = 22). The median wear time required for a valid day was 600 min, and between two and five valid days was required for a patient to be included in the analysis. The most common measures of physical activity were steps (n = 20), activity counts (n = 15), and time spent in moderate‐to‐vigorous physical activity (n = 14). Only three studies validated accelerometers in a heart failure population, showing that their accuracy deteriorates at slower speeds. Studies failed to report between one and six (median 4) of the 12 scored items, with non‐wear time criteria and valid day definition being the most underreported items.

Conclusions

The use of accelerometers in cardiology lacks consistency and reporting on data collection, and processing methods need to be improved. Furthermore, calculating metrics based on raw acceleration and machine learning techniques is lacking, opening the opportunity for future exploration. Therefore, we encourage researchers and clinicians to improve the quality and transparency of data collection and processing by following our proposed practical recommendations for using accelerometers in patients with cardiovascular diseases, which are outlined in the article.

Rest Redistribution Does Not Alter Hormone Responses in Resistance-Trained Women

Merrigan, JJ, Tufano, JJ, Fields, JB, Oliver, JM, and Jones, MT. Rest redistribution does not alter hormone responses in resistance-trained women. J Strength Cond Res 34(7): 1867-1874, 2020-The purpose was to examine acute effects of rest redistribution (RR) on perceptual, metabolic, and hormonal responses during back squats. Twelve resistance-trained women (training age 5 ± 2 years; one repetition maximum [1-RM] per body mass, 1.6 ± 0.2) performed traditional (TS, 4 sets of 10 repetitions with 120 seconds interset rest) and RR sets (4 sets of two 5 repetition clusters with 30-second intraset rest and 90-second interset rest) in counterbalanced order, separated by 72 hours. Both conditions were performed at 70% 1RM with 360 seconds of total rest. Ratings of perceived exertion (RPE) were taken after each set. Blood was sampled at baseline, after each set, and at 5, 15, 30, and 60 minutes, as well as 24 and 48 hours after training. Alpha level was p ≤ 0.05. The RPE progressively increased throughout both conditions (p = 0.002) with a greater overall mean for TS (5.81 ± 0.14) than RR (4.71 ± 0.14; p = 0.003). Lactate increased above baseline and remained elevated through 15 minutes post in both conditions (4.00 ± 0.76; p = 0.001), with greater lactate levels for TS (6.33 ± 0.47) than RR (4.71 ± 0.53; p < 0.001). Total testosterone was elevated after set 2 (0.125 ± 0.02; p = 0.011), but no other time point, while free testosterone remained unchanged. Growth hormone continually rose from baseline to set 3 and returned to baseline by 60 minutes post (20.58 ± 3.19). Cortisol and creatine kinase did not change over time. No condition × time interactions existed for any hormone (p > 0.05). Use of rest redistribution resulted in lower perceived effort and lactate responses. Yet, hormone responses during rest redistribution were no different from TS.

Effect of different interset rest intervals on mean velocity during the squat and bench press exercises

This study aimed to compare the effect of three interset rest intervals (1, 3, and 5 minutes) on (I) mean velocity during a resistance training session conducted in a Smith machine with the squat and bench press exercises, and (II) the pre- and post-exercise force-velocity relationship. Fifteen male university students completed three sessions (i.e., Rest 1', Rest 3', and Rest 5') consisting of three sets of five repetitions against the 10RM load during the squat and bench press exercises. The force-velocity relationship (maximal values of force [F₀], velocity [v₀], and power [P_max]) was evaluated at the beginning and at the end of each session with the countermovement jump and bench press throw exercises. During training, mean velocity was slower in sets 2 and 3 of the Rest 1' protocol compared to Rest 3' and Rest 5', but no significant differences were present between Rest 3' and Rest 5'. After training, there was a significant decrease in F₀ (p = 0.017) and P_max (p = 0.010), but not in v₀ (p = 0.259). These results support the Rest 3' as the most time-efficient protocol, among those analysed, for the maintenance of high mean velocities during training sessions not leading to failure.

Comparable endocrine and neuromuscular adaptations to variable vs. constant gravity-dependent resistance training among young women

Background

Variable resistance has been shown to induce greater total work and muscle activation when compared to constant resistance. However, little is known regarding the effects of chronic exposure to variable resistance training in comparison with constant resistance training. The aim of the present study was therefore to examine the effects of chain-loaded variable and constant gravity-dependent resistance training on resting hormonal and neuromuscular adaptations.

Methods

Young women were randomly assigned to variable resistance training (VRT; n = 12; age, 23.75 ± 3.64 years; and BMI, 26.80 ± 4.21 kg m⁻²), constant resistance training (CRT; n = 12; age, 23.58 ± 3.84 years; BMI, 25.25 ± 3.84 kg m⁻²), or control (Con; n = 12; age, 23.50 ± 2.93 years; BMI, 27.12 ± 12 kg m⁻²) groups. CRT performed 8-week total-body free-weight training three times per week with moderate-to-high intensity (65–80% 1RM; periodized). VRT was the same as CRT but included variable resistance via chains (15% of total load). Resting serum samples were taken before and after the 8-week intervention for GH, IGF-1, cortisol, myostatin, and follistatin analyses.

Results

Both VRT and CRT groups displayed moderate-to-large significant increases in GH (197.1%; ES = 0.78 vs. 229.9%; ES = 1.55), IGF-1 (82.3%; ES = 1.87 vs. 66%; ES = 1.66), and follistatin (58.8%; ES = 0.80 vs. 49.15%; ES = 0.80) and decreases in cortisol (− 19.9%; ES = − 1.34 vs. − 17.1%; ES = − 1.05) and myostatin (− 26.9%; ES = − 0.78 vs. − 23.2%; ES = − 0.82). Also, VRT and CRT resulted in large significant increases in bench press (30.54%; ES = 1.45 vs. 25.08%; ES = 1.12) and squat (30.63%; ES = 1.28 vs. 24.81%; ES = 1.21) strength, with no differences between groups.

Conclusions

Implementing chain-loaded VRT into a periodized resistance training program can be an effective alternative to constant loading during free-weight RT among untrained young women.

Effect of Robot-Assisted Gait Training on Selective Voluntary Motor Control in Ambulatory Children with Cerebral Palsy

This pilot study investigated the efficacy of a four week robot-assisted gait training in twelve childrenwith spastic diparesis. Short-term results and a 3-month follow-up showed statistically significantly increased selective motor control, walking farther distances, gross motor score, and decreased joint contractures.

Acute effects of shorter but more frequent rest periods on mechanical and perceptual fatigue during a weightlifting derivative at different loads in strength-trained men

Traditional sets can be fatiguing, but redistributing rest periods to be shorter and more frequent may help maintain peak vertical barbell displacement (DISP) and reduce concentric repetition duration (CRDI), peak velocity decline (PVD) and perceptual exertion (RPE) across multiple repetitions, sets and loads during clean pulls. Fifteen strength-trained men performed: 3 traditional sets of 6 clean pulls using 80% (TS80), 100% (TS100) and 120% (TS120) of power clean 1RM with 180 seconds of inter-set rest; and 3 'rest redistribution' protocols of 9 sets of 2 clean pulls using 80% (RR80), 100% (RR100) and 120% (RR120) of power clean 1RM with 45 seconds of inter-set rest. DISP was greater during RR100 (g = 0.39) and RR120 (g = 0.56) compared to TS100 and TS120, respectively. In addition, PVD was less during RR120 than TS120 (g = 1.18), while CRDI was greater during TS100 (g = 0.98) and TS120 (g = 0.89) compared to RR100 and RR120, respectively. Also, RR protocols resulted in lower RPE across the sets at all loads (g = 1.11-1.24). Therefore, RR generally resulted in lower perceptual and mechanical fatigue, evidenced by lower RPE, PVD, CRDI and greater DISP than TS, and these differences became even more exaggerated as the barbell load and the number of sets performed increased.

Magnitude and Reliability of Velocity and Power Variables During Deadlifts Performed With and Without Lifting Straps

Jukic, I, García-Ramos, A, Malecek, J, Omcirk, D, and Tufano, JJ. Magnitude and reliability of velocity and power variables during deadlifts performed with and without lifting straps. J Strength Cond Res XX(X): 000-000, 2020-This study aimed to compare the magnitude and reliability of mean velocity (MV), peak velocity (PV), mean power (MP), and peak power (PP) between deadlifts performed with (DLw) and without (DLn) lifting straps. Sixteen resistance-trained men performed a DLn 1-repetition maximum (1RM) session followed by 4 experimental sessions (2 with each deadlift variant in a randomized order). Each experimental session comprised lifts at 20, 40, 60, and 80% of the DLn 1RM. No significant differences were found between DLw and DLn for MV, MP, PV, and PP at any load (p = 0.309-1.00; g = 0.00-0.19). All mechanical variables showed an acceptable reliability for both deadlift conditions at each relative load (coefficient of variation [CV] <8%; intraclass correlation coefficient [ICC] > 0.70; g < 0.5) with the only exception of MV at 60% 1RM for DLw (ICC = 0.62) and at 40% 1RM for DLn (ICC = 0.65). Furthermore, MV and PV generally had lower within-subject CV (CV = 3.56-5.86%) than MP and PP (CV = 3.82-8.05%) during both deadlift conditions. Our findings suggest that sport professionals might not need to consider implementing lifting straps with the aim to maximize velocity and power outputs with submaximal loads in a deadlift exercise. Because all mechanical variables measured showed an acceptable level of reliability for both DLw and DLn, they can all be used to track changes in performance during the deadlift exercise. However, velocity variables were slightly more consistent (lower CV), which makes them more appropriate to track DLw and DLn performance changes.

Can Post-Activation Performance Enhancement (PAPE) Improve Resistance Training Volume during the Bench Press Exercise?

Background: The aim of the present study was to evaluate the effects of post-activation performance enhancement (PAPE) on resistance training volume during the bench press exercise (BP). The study included 12 healthy strength-trained males (age 25.2 ± 2.1 years, body mass 92.1 ± 8.7 kg, BP one-repetition maximum (1RM) 28.8 ± 10.5 kg, training experience 6.3 ± 2.1 years). Methods: The experiment was performed following a randomized crossover design, where each participant performed two different exercise protocols with a conditioning activity (CA) consisting of the BP with three sets of three repetitions at 85% 1RM (PAPE), and a control without the CA (CONT). To assess the differences between PAPE and CONT, the participants performed three sets of the BP to volitional failure at 60% 1RM. The differences in the number of performed repetitions (REP), time under tension (TUT), peak power output (PP), mean of peak power output (PPMEAN), mean power output (MP), peak bar velocity (PV), mean of peak bar velocity (PVMEAN), and mean bar velocity (MV) between the CONT and PAPE conditions were examined using repeated measures ANOVA. Results: The post-hoc analysis for the main condition effect indicated significant increases in TUT (p < 0.01) for the BP following PAPE, compared to the CONT condition. Furthermore, there was a significant increase in TUT (p < 0.01) in the third set for PAPE compared to the CONT condition. No statistically significant main effect was revealed for REP, PP, PV, PPMEAN, PVMEAN, MP, and MV. Conclusion: The main finding of the study was that the PAPE protocol increased training volume based on TUT, without changes in the number of preformed REP.

Cluster vs. traditional training programmes: changes in the force-velocity relationship

This randomised controlled study examined the force-velocity relationship changes (force and velocity axis intercepts, slope and estimated maximum power) in response to 5-week training programmes differing in the set configuration. For each session, the traditional group performed 4 sets of 8 repetitions with 5 min of rest between sets and exercises, while the cluster group completed 16 sets of 2 repetitions with 1 min of rest between sets and 5 min between exercises. Both programmes were performed with the 10-repetition maximum load, including bench press, parallel squat, lat pull-down and leg curl exercises. Individual force-velocity profiles were obtained for bench press and squat using a linear velocity transducer before and after the intervention, along with lactate and mechanical performance during the intervention. Results showed in bench press similar changes of the force-velocity profile after both protocols (no shift of the slope and higher force and velocity axis intercept values). For the squat, significant changes in the slope (P = 0.001) and the velocity intercept (P = 0.002) towards a velocity profile were observed after cluster but not after traditional training. These results suggest that set configuration may modulate changes of force-velocity relationship, especially for squat.

The Effects of the Movement Tempo on the One-Repetition Maximum Bench Press Results

Different tempos of movement can be used during resistance training, but programming them is often a trial-and-error practice, as changing the speed at which the exercise is performed does not always correspond with the tempo at which the 1-repetition-maximum occurred. Therefore, the aim of this study was to determine the effect of different movement tempos during the bench press (BP) exercise on the one-repetition maximum (1RM) load. Ninety men (age = 25.8 ± 5.3 years, body mass = 80.2 ± 14.9 kg), with a minimum one year of resistance training experience took part in the study. Using a randomized crossover design, each participant completed the BP 1RM test with five different movement tempos: V/0/V/0, 2/0/V/0, 5/0/V/0, 8/0/V/0 and 10/0/V/0. Repeated measures ANOVA compared the differences between the 1RM at each tempo. The 1RM load was significantly greater during V/0/V/0 and 2/0/V/0 compared to 5/0/V/0, 8/0/V/0, and 10/0/V/0 (p < 0.01). Furthermore, the 1RM load was significantly greater during 5/0/V/0 compared to 8/0/V/0 and 10/0/V/0 (p < 0.01), but there were no differences between either V/0/V/0 and 2/0/V/0 (p = 0.92) or between 8/0/V/0 and 10/0/V/0 (p = 0.08). Therefore, different movement tempos used during training should be accompanied by their own tempo-specific 1RM testing, as slower eccentric phases significantly decrease maximal concentric performance. Furthermore, 1RM test procedures should include information about the movement tempo used during the test protocol. In addition, the standardization of the tempo should be taken into account in investigations that use the 1 RM test to assess the effects of any treatment on maximal muscle strength.

The interplay between internal and external load parameters during different strength training sessions in resistance-trained men

External load influences internal load in resistance training (RT). The purpose of the present study was to compare the total volume-load, perceptual and stress responses during three different RT protocols. Twelve resistance-trained men completed three different RT protocols with the back squat and bench press exercises: (1) power (POW) (5 sets of 6 repetitions at 50%1RM, 2-min of rest), (2) hypertrophy (HYP) (5 sets-to-failure at 75%1RM, 2-min of rest), and (3) strength (STR) (5 sets-to-failure at 90%1RM, 3-min of rest). Volume-load (kg × reps.), session rating of perceived exertion (sRPE), training impulse (TRIMP; reps. × sRPE), cortisol, immunoglobulin A (IgA), lactate, and creatine kinase (CK) were assessed before and/or after the sessions. HYP was the most demanding session in terms of volume-load (p < 0.001), TRIMP (p < 0.001), cortisol (p = 0.001), lactate (p < 0.001), and CK (p = 0.001). Despite POW exhibited a greater volume-load than STR (p = 0.016), the latter exhibiting a greater sRPE (p < 0.001), and a greater post-session CK (p = 0.05). However, the TRIMP of STR and POW were not statistically different (152 vs. 260 AU; p = 0.089). These specific responses could be meditated by the presence of muscular failure. When pooling all the sessions, significant correlations were revealed among external and internal stress markers (r = 0.35-0.80; p ≤ 0.05). The use of TRIMP could be recommended as a simple and valid monitoring tool which integrates into a single parameter the internal and the external loads of RT sessions.

Reliability and Test-Retest Agreement of Mechanical Variables Obtained During Countermovement Jump

The countermovement jump (CMJ) is often used as performance measure and monitoring tool. Traditionally, jump height (JH) is most often studied and reported, but other variables (e.g. force, velocity, power) can also be obtained during CMJ testing on a force plate. The aim of this study was to determine the intra-rater reliability of mechanical variables obtained during CMJs. For this, 41 physically active men (24 ± 4 years) performed four CMJs on a force plate with an interval of 48 to 168 hours (test-retest design). Six variables were analyzed: 1) jump height (JH), 2) peak force (PF), 3) peak power (PP), 4) velocity at takeoff (VTO), 5) rate of force (RFD) and 6) power (RPD) development. Five variables showed to be reliable (i.e. CV < 10%), except RFD (CV of 12.9%). Although JH exhibited an acceptable level of reliability (r = 0.94 and CV = 5.8%), better scores were observed for PF, VTO, and PP (CV ranging from 2.5 to 5.1%). The PF showed the best reliability scores (r = 0.99 and CV = 2.5%) and RPD, a relatively unexamined variable compared to the others, showed an acceptable level of reliability (r = 0.96 and CV = 7.8%). Therefore, JH, PF, PP, VTO, and RPD demonstrated acceptable scores of reliability. PF seems to be the most appropriate variable to use when small changes in performance are expected. Future studies should investigate the importance of RPD for performance evaluation.

Acute fatigue affects reaction times and reaction consistency in Mixed Martial Arts fighters

Mixed Martial Arts (MMA) is a multielement combat sport where fighters need to quickly react to an opponent’s movements under fatigued conditions. Research indicates that fast reaction time is important in many sports, but the effect of fatigue has shown negative, null, or even positive influences on reaction time. However, few studies have been conducted in a controlled setting, especially using MMA figthers, whose matches are frequently resolved in a split-second. Therefore, this study investigated whether acute neuromuscular fatigue affects reaction and movement times, and their consistency in MMA fighters (N = 45). Before and after an upper-body Wingate test, a simple visual reaction time task was completed. Results showed a significant negative effect of fatigue on the reaction times and their consistency, with longer reactions (1.5% change) and lower consistency (14.7% change) after the Wingate test. Further, greater amounts of fatigue during the Wingate test seemed to negatively affect the consistency of post-Wingate movement time. Due to cumulative fatigue and the dynamic nature of MMA, our data indicate that not only the decrements in aerobic and anaerobic power likely affect a fighter’s performance, but their reaction time and motor time may also be compromised during a fight.

Could inter-set stretching increase acute neuromuscular and metabolic responses during resistance exercise?

This study investigated the acute effects of inter-set static stretching (ISS) during resistance exercise (RE) on the subsequent neuromuscular and metabolic responses. Twelve resistance-trained men performed three different knee extension RE protocols comprised of seven sets of 10 repetitions in a counterbalanced fashion. The three protocols were: 1) ISS (subjects performed 25 sec of quadriceps stretching between sets during 40 sec rest interval); 2) control (CON, subject passively rested between sets for 40 sec); 3) traditional (TRA, subject passively rested between sets for 120 sec). Total work was lower (p < 0.05) in ISS than CON and TRA (p <0.05). The fatigue index was greater (p < 0.05) in ISS compared with CON and TRA. ISS also resulted in lower (p < 0.05) electromyography (EMG) amplitude during the 6th and 7th sets compared with TRA. Additionally, EMG frequency was lower (p < 0.05) from the 3rd to 5th sets during ISS compared to CON, and from the 3rd to 7th sets compared to TRA. Muscle swelling and blood lactate similarly increased (p > 0.05) in response to all protocols. These results indicate that ISS negatively impacts neuromuscular performance, and does not increase the metabolic stress compared to passive rest intervals.

Traditional sets versus rest-redistribution: a laboratory-controlled study of a specific cluster set configuration at fast and slow velocities

This study investigated redistributing long inter-set rest intervals into shorter but more frequent intervals at 2 different concentric velocities. Resistance-trained men performed 4 randomised isokinetic unilateral knee extension protocols, 2 at 60°·s^-1 and 2 at 360°·s^-1. At each speed, subjects performed 40 repetitions with 285 s of rest using traditional sets (TS; 4 sets of 10 with 95 s of inter-set rest) and rest-redistribution (RR; 20 sets of 2 with 15 s inter-set rest). Before and at 2, 5, and 10 min after exercise, tensiomyography (TMG) and oxygenation (near-infrared spectroscopy; NIRS) were measured. NIRS was also measured during exercise, and rating of perceived exertion (RPE) was recorded after every 10 repetitions. At both speeds, RR displayed greater peak torque, total work, and power output during latter repetitions, but there were no differences between TS or RR when averaging all 40 repetitions. The RPE was less during RR at both speeds (p < 0.05). RR increased select muscle oxygen saturation and blood flow at both speeds. There were no effects of protocol on TMG, but effect sizes favoured a quicker recovery after RR. RR was likely beneficial in maintaining performance compared with the latter parts of TS sets and limiting perceived and peripheral fatigue. Novelty Although effective at slow velocities, rest-redistribution was likely more effective during high-velocity movements in this study. Rest-redistribution maintained the ability to produce force throughout an entire range of motion. Rest-redistribution reduced RPE during both high-velocity and high-force movements.