Interset Rest Research Articles

Reducing the Loss of Velocity and Power in Women Athletes via Rest Redistribution.

To examine rest redistribution (RR) effects on back squat kinetics and kinematics in resistance-trained women. Twelve women from strength and college sports (5.0 [2.2]y training history) participated in the randomized crossover design study with 72hours between sessions (3 total). Participants completed 4 sets of 10 repetitions using traditional sets (120-s interset rest) and RR (30-s intraset rest in the middle of each set; 90-s interset rest) with 70% of their 1-repetition maximum. Kinetics and kinematics were sampled via force plate and 4 linear position transducers. The greatest value of repetitions 1 to 3 (peak repetition) was used to calculate percentage loss, [(repetition 10-peak repetition)/(peak repetition) × 100], and maintenance, {100-[(set mean-peak repetition)/(peak repetition)] × 100}, of velocity and power for each set. Repeated-measures analysis of variance was used for analyses (P < .05). Mean and peak force did not differ between conditions. A condition × repetition interaction existed for peak power (P = .049) but not for peak velocity (P = .110). Peak power was greater in repetitions 7 to 9 (P < .05; d = 1.12-1.27) during RR. The percentage loss of velocity (95% confidence interval, -0.22% to -7.22%; P = .039) and power (95% confidence interval, -1.53% to -7.87%; P = .008) were reduced in RR. Mean velocity maintenance of sets 3 (P = .036; d = 1.90) and 4 (P = .015; d = 2.30) and mean power maintenance of set 4 (P = .006; d = 2.65) were greater in RR. By redistributing a portion of long interset rest into the middle of a set, velocity and power were better maintained. Therefore, redistributing rest may be beneficial for reducing fatigue in resistance-trained women.

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.

Rest Redistribution Functions as a Free and Ad-Hoc Equivalent to Commonly used Velocity-Based Training Thresholds During Clean Pulls at Different Loads.

This study determined whether redistributing total rest time into shorter, but more frequent rest periods could maintain velocity and power output during 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 during 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. The total number of repetitions performed above 10 and 20% velocity loss thresholds, mean and peak velocity maintenance (the average of all 18 repetitions relative to the best repetition; MVM, PVM), and decline (the worst repetition relative to the best repetition; MVD, PVD) were calculated. For MVM, PVM, MVD, and PVD, there were small-to-moderate effect sizes in favour of RR80 and RR100, but large effects favouring RR120, compared to their respective TS protocols. The number of repetitions within a 20% velocity loss threshold was 17.7 ± 0.6 during RR and 16.5 ± 2.4 during TS (effect size 0.69); and the number of repetitions within a 10% velocity loss threshold was about 13.1 ± 3.7 during RR and 10.7 ± 3.6 during TS (effect size 0.66). Therefore, RR generally allowed for a better overall maintenance of velocity and power, especially at heavy loads. Coaches who wish to implement velocity-based training, but who do not wish to purchase or use the associated equipment, may consider rest-redistribution to encourage similar training stimuli.

The Effects of Acute Bouts of Whole Body Vibration on Central Hemodynamics in Frail Older Adults: A Pilot Study

Introduction: This study investigates whether an acute bout of whole body vibration (WBV): (i) improves measures of central hemodynamics and (ii) can be completed without inducing orthostatic intolerance in frail older adults. Methods: Nine rest home residents participated in a cross-over design incorporating WBV and non-vibrational control conditions (CON) on 2 separate testing days. The order of the two testing conditions was randomized. Participants completed 10 sets of 60 seconds of WBV training or CON with an inter-set rest period of 60 seconds. Results: During training, no interaction or between-condition effects were observed for any variable. Following training, there was an interaction effect reported for augmentation index (AIx) (P < 0.019) and a significant large increase in AIx for WBV (P = 0.020, Eta = 0.202). Three participants exhibited one-off notable decreases in either central systolic or diastolic blood pressure. Conclusion: An acute bout of WBV is a safe training method for frail older adults.

Validity and Reliability of a 10 Hz GPS for Assessing Variable and Mean Running Speed.

Our purpose was to assess the 10 Hz Viper GPS devices’ validity and reliability (STATSport) in both instantaneous and mean speed measuring in accelerations and decelerations in straight-line running conditions. Eight amateur team sport players participated in the study, performing firstly 21 x 40 m sprints at submaximal incremental speed, and secondly 21 x 40 m sprints, with the first stage consisting of submaximal incremental speed, and the second stage of subsequent submaximal decreasing speed. Criteria systems used to evaluate the GPS validity were a radar gun for instantaneous speed, and timing-gates for mean speed. Reliability was measured with two GPS devices carried by the same athlete, running 10 x (20 m + 20 m) sprints with a 180º change of direction and a 10 s inter-set rest interval. Results showed an agreement between GPS devices and the criteria systems measuring instantaneous speed (r = 0.98; standardized mean bias (SMB) = -0.07; standard typical error (STE) = 0.22) and mean speed (r = 0.99; SMB = 0.38; STE = 0.17). The reliability study presented a nearly perfect correlation between devices, a trivial SMB and a small STE (r = 0.97; SMB = 0.04; STE = 0.23). 10 Hz GPS devices are an adequate solution to monitor straight-line running speed in acceleration and deceleration conditions, but we would like to draw attention to the small errors and bias detected, such as the speed overestimation compared with timing gates.

Myofibrillar protein synthesis and muscle hypertrophy individualized responses to systematically changing resistance training variables in trained young men.

The manipulation of resistance training (RT) variables is used among athletes, recreational exercisers, and compromised populations (e.g., elderly) attempting to potentiate muscle hypertrophy. However, it is unknown whether an individual's inherent predisposition dictates the RT-induced muscle hypertrophic response. Resistance-trained young [26 (3) y] men (n = 20) performed 8 wk unilateral RT (2 times/wk), with 1 leg randomly assigned to a standard progressive RT [control (CON)] and the contralateral leg to a variable RT (VAR; modulating exercise load, volume, contraction type, and interset rest interval). The VAR leg completed all 4 RT variations every 2 wk. Bilateral vastus lateralis cross-sectional area (CSA) was measured, pre- and post-RT and acute integrated myofibrillar protein synthesis (MyoPS) rates were assessed at rest and over 48 h following the final RT session. Muscle CSA increase was similar between CON and VAR (P > 0.05), despite higher total training volume (TTV) in VAR (P < 0.05). The 0-48-h integrated MyoPS increase postexercise was slightly greater for VAR than CON (P < 0.05). All participants were considered "responders" to RT, although none benefited to a greater extent from a specific protocol. Between-subjects variability (MyoPS, 3.30%; CSA, 37.8%) was 40-fold greater than the intrasubject (between legs) variability (MyoPS, 0.08%; CSA, 0.9%). The higher TTV and greater MyoPS response in VAR did not translate to a greater muscle hypertrophic response. Manipulating common RT variables elicited similar muscle hypertrophy than a standard progressive RT program in trained young men. Intrinsic individual factors are key determinants of the MyoPS and change in muscle CSA compared with extrinsic manipulation of common RT variables.NEW & NOTEWORTHY Systematically manipulating resistance training (RT) variables during RT augments the stimulation of myofibrillar protein synthesis (MyoPS) and training volume but fails to potentiate muscle hypertrophy compared with a standard progressive RT. Any modest further MyoPS increase and higher training volumes do not reflect in a greater hypertrophic response. Between-subject variability was 40-fold greater than the variability promoted by extrinsic manipulation of RT variables, indicating that individual intrinsic factors are stronger determinants of the hypertrophic response.

The Effect of Self-Paced and Prescribed Inter-Set Rest Strategies on Performance in Strength Training.

To assess pacing strategies using prescribed and self-selected inter-set rest periods and their influence on performance in strength trained athletes. Sixteen strength-trained male athletes completed three randomised heavy-strength training sessions (five sets, five repetitions) with different inter-set rest periods. The inter-set rest periods were: 3 minute (3MIN), 5 minute (5MIN) and Self-Selected (SS). Mechanical (power, velocity, work and displacement), surface muscle activity (sEMG) and subjective (Rating of Perceived Exertion -RPE) and readiness to lift (RTL) data were recorded for each set. SS condition inter-set rest periods increased from sets 1 to 4 (207.52s > 277.71 s; p=0.01). No differences in mechanical performance were shown between the different inter-set rest period conditions. Power output (210 W; 8.03%) and velocity (0.03 m.s-1; 6.73%) decreased as sets progressed for all conditions (p<0.001) from set 1 to set 5. No differences in sEMG activity between conditions were shown, however vastus medialis sEMG decreased as the sets progressed for each condition (1.75%; p=0.005). All conditions showed increases in RPE as sets progressed (set 1: 6.1; set 5: 7.9) (p<0.001). Participants reported greater readiness to lift in the 5MIN condition (7.81) compared to the 3MIN (7.09) and SS (7.20) conditions (p<0.001). Self-selecting inter-set rest periods does not significantly change performance compared to 3MIN and 5 MIN conditions.. Given the opportunity, athletes will vary their inter-set rest periods to complete multiple sets of heavy strength training. Self-selection of inter-set rest periods may be a feasible alternative to prescribed inter-set rest periods.

Neuromuscular Factors Contributing to Reductions in Muscle Force After Repeated, High-Intensity Muscular Efforts

Multiple neuromuscular processes contribute to the loss of force production following repeated, high-intensity muscular efforts; however, the relative contribution of each process is unclear. In Experiment 1, 16 resistance trained men performed six sets of unilateral isometric plantar flexor contractions of the right leg (3 s contraction/2 s rest; 85% maximal voluntary contraction torque; 90-s inter-set rest) until failure with and without caffeine ingestion (3 mg kg-1) on two separate days. Corticospinal excitability and cortical silent period (cSP) were assessed before and immediately, 10 and 20 min after the exercise. In Experiment 2, electrically evoked tetanic force and persistent inward current (PIC)-mediated facilitation of the motor neuron pool (estimated using neuromuscular electrical stimulation with tendon vibration) were assessed before and after the same exercise intervention in 17 resistance trained men. Results showed decreases in peak plantar flexion torque (Experiment 1: -12.2%, Experiment 2: -16.9%), electrically evoked torque (20 Hz -15.3%, 80 Hz -15.3%, variable-frequency train -17.9%), and cSP (-3.8%; i.e., reduced inhibition) post-exercise which did not recover by 20 min. Electromyographic activity (EMG; -6%), corticospinal excitability (-9%), and PIC facilitation (-24.8%) were also reduced post-exercise but recovered by 10 min. Caffeine ingestion increased torque and EMG but did not notably affect corticospinal excitability, PIC amplification, or electrically evoked torque. The data indicate that a decrease in muscle function largely underpins the loss of force after repeated, high-intensity muscular efforts, but that the loss is exacerbated immediately after the exercise by simultaneous decreases in corticospinal excitability and PIC amplitudes at the motor neurons.

Endurance is Augmented By Greater Blood Flow Restriction Pressures: Muscle Size and Strength Are Not

PURPOSE: The importance of training to failure, especially when using low-loads (i.e., 30% 1RM) is well established. However, it remains unknown if lifting 15% 1RM can disrupt muscular blood flow enough to induce failure and stimulate adaptation. This study was designed to compare muscular adaptations between training with 15% 1RM and 70% 1RM, to determine if blood flow restriction (BFR) could augment the response to 15% 1RM, and if the effect of BFR is pressure dependent [40% versus 80% arterial occlusion pressure (AOP)]. METHODS: 40 untrained participants performed 4 sets of unilateral knee extension 2x/week for 8 weeks, with two conditions, one per leg. Conditions (label) were: 15% 1RM 0% AOP (15/0), 15% 1RM 40% AOP (15/40), 15% 1RM 80% AOP (15/80), 70% 1RM 0% AOP (70/0). Sets were stopped at 90 repetitions or volitional failure, as determined by an inability to maintain metronome cadence (2 s/contraction) or full repetitions. Inter-set rest was 30 s for 15/0, 15/40, 15/80 and 90 s for 70/0. A 10 cm wide nylon cuff was used for BFR. RESULTS: Data presented as [mean change (95% CI)]. There were condition x time interactions for 1RM (p<.001) and endurance (p=.028). 70/0 increased 1RM [3.15 (2.04, 4.25) kg]; 15/0 [-0.06 (-1.13, 1.01), 15/40 [0.066 (-1.06, 1.20), and 15/80 [0.68 (-0.41, 1.79) did not. Increased endurance was greatest for 15/80 [6.2 (4.3, 8.0)] compared to 15/0 [4.2 (2.4, 6.0)], 15/40 [4.7 (2.8, 6.5)], and 70/0 [4.0 (2.2, 5.9)]. There were main effects of time for isometric MVC [10.51 (3.87, 17.16) Nm, p=.002] and isokinetic MVC at 180°/s [change = 8.61 (5.54, 11.68) Nm, p<.001]. Isokinetic MVC at 60°/s did not change [2.45 (-1.84, 6.74) Nm, p=.261]. There were no condition x time interactions for muscle thickness sites (all p≥.313), which increased over time (all p<.001). There were main effects of condition for each site (70/0 was greater, all p<.001) except 30% lateral (p=.059). CONCLUSION: Most muscle strength and size changes appear similar despite large discrepancies in training load and restriction pressure. While the change in 1RM with high-load may be due to motor learning or practicing, the greater endurance adaptation favoring high restriction pressures should be explored further regarding underlying mechanisms. These results are relevant to mechanistic exploration, therapeutic purposes, and program design.

Anabolic Signaling Phosphorylation Does Not Explain Differential Muscle Protein Synthesis with Intra-Set Rest Manipulation

Power development is imperative for dynamic sport athletes. Cluster sets (CLU) are an effective method to allay the progressive decrement in power output normally observed in a traditional (TRD) resistance exercise strategy. CLU configurations incorporate a brief intra-set rest period to preserve velocity and power. Despite favorable performance, we previously established that TRD configurations elicit higher myofibrillar protein synthesis (MPS) rates when compared to CLU. However, it remains unclear if hallmark readouts related to mTORC1-signaling underlie this observation. PURPOSE: To elucidate anabolic signaling mechanisms driving differential MPS rates observed between CLU and TRD paradigms of the barbell back squat in trained men and women. METHODS: In randomized crossover design, 8 resistance-trained adults (7M, 1F; 23 ± 4 y; LBM, 63 ± 9 kg; back squat 1RM, 150 ± 26 kg) performed an acute bout of either CLU (4 sets × (2 × 5) repetitions, 30s intra-set rest, 90s inter-set rest) or TRD (4 sets × 10 repetitions, 120s inter-set rest) barbell back squats at ~70% 1RM. Volume load and total rest were matched between bouts. Participants ingested 20g of whey protein immediately before and after exercise. Muscle biopsies were collected at rest and at 0, 2, and 5 h post-exercise during primed-continuous L-[ring-13C6]phenylalanine infusions. Total and phosphorylated states of targeted proteins were assessed through immunoblotting. Data was normalized to an internal loading control. RESULTS: The phosphorylation of focal adhesion kinase (FAK) was doubled with TRD, but not significantly different, from CLU (TRD 2.1 ± 0.9-fold increase from baseline; CLU 1.3 ± 0.9-fold; p>0.05). Downstream targets of mTORC1 also showed no differences in phosphorylation between paradigms (4E-BP1: TRD 1.6 ± 0.3-fold, CLU 0.4 ± 0.2-fold; p706SK: TRD 1.5 ± 0.4-fold, CLU 0.9 ± 0.4-fold). Similarly, there was no difference in AMPK phosphorylation between conditions (TRD 1.3 ± 0.9-fold; CLU 0.9 ± 0.7-fold). CONCLUSION: Our data demonstrated that changes in protein phosphorylation as noted by various readouts within the mTORC1 pathway do not underpin the greater post-exercise muscle protein synthetic response with TRD versus CLU-style in resistance trained men and women.

Cytokine Response to Traditional and Cluster Sets in Resistance-trained Women

Resistance exercise that incorporates intra-set rest between repetition blocks (i.e., cluster sets [CS]) can produce a smaller metabolic stress and endocrine response than traditional sets (TS). PURPOSE: To examine the effect of CS on the acute cytokine response in resistance trained women. METHODS: 12 resistance-trained women (mean ± SE; 23.7 ± 1.1 years; 160.1 ± 1.5 cm; 62.5 ± 1.7 kg; 5 ± 1 years training) completed 3 sessions in the follicular phase. One-repetition maximum (1RM) back squat (BS) (98.7 ± 4.1 kg), and BS:body mass (1.6 ± 0.1) were determined in Session 1. For Session 2 (3 days post Session 1) and Session 3 (7 days post Session 2), subjects were randomly assigned to either 4 sets of 10 reps with 120 seconds (s) inter-set rest (TS) or 4 x (2 x 5 reps) with 30s intra-set rest and 90s inter-set rest (CS). All performed both protocols at 70% 1RM BS. Instructions were to perform every rep “as explosively as possible”. Blood was collected pre-exercise (PRE), immediately after sets 1, 2, 3, 4 (IP), and at 5 (+5), 15 (+15), 30 (+30), and 60 (+60) min post-exercise and analyzed for interleukin (IL)-1β, IL-2, IL-6, IL-8, IL 10, and IL-15. Data were analyzed using repeated measures ANOVAs (2 × 9). RESULTS: A significant main effect of time (p<0.05) was found for IL-1β, IL-2, IL-8, IL-10, and IL-15. Concentration of IL-1β was smaller at +5 (3.9 ± 0.4 ng/mL), +15 (3.6 ± 0.4) +30 (3.5 ± 0.3), and +60 (3.7 ± 0.4) compared to IP (4.1 ± 0.4). IL-2 was greater after set 1 (10.8 ± 1.0 ng/mL), and set 2 (11.0 ± 1.2) compared to PRE (10.2 ± 1.0), and smaller at +30 (9.9 ± 1.0) compared to IP (11.0 ± 1.0). IL-8 was greater after set 1 (8.4 ± 0.6 ng/mL), set 2 (8.6 ± 0.7), and set 3 (8.5 ± 0.7) compared to PRE (8.0 ± 0.6). IL-10 was smaller at +30 (31.3 ± 7.4 ng/mL) compared to PRE (34.0 ± 7.4), and also smaller at +15 (32.6 ± 7.9) +30 (31.3 ± 7.4), and +60 (33.4 ± 8.6) compared to IP (38.0 ± 8.6). IL-15 was greater at IP (15.5 ± 4.0 ng/mL) compared to PRE (13.4 ± 3.5), and smaller at PRE (13.4 ± 3.5), +30 (11.9 ± 3.3), and +60 (11.6 ± 3.2) compared to IP (15.5 ± 4.0). No condition × time point effects were observed. CONCLUSIONS: Both TS and CS induced an acute cytokine response in resistance-trained women; incorporating intra-set rest (CS) did not appear to affect this cytokine response. Supported in part by a grant from the National Strength and Conditioning Association Foundation.

Impact Of Exercise Intensity And Resting Intervals During Resistance Exercise On Acute Sparc Secretion In Healthy Young Males: A Pilot Study

PURPOSE: Recently, it is going noteworthy that an exercise-induced novel myokine, secreted protein acidic and rich in cysteine (SPARC) has the potential to prevent colon cancer. Moreover, regular resistance exercise (RE) has been known to reduce the mortality risk of cancer. From these points of view, RE might prevent colon tumorigenesis via increasing SPARC, while it is unclear whether resistance exercise can promote SPARC secretion in human. Thus, the purpose of this study was to investigate the both effects of exercise intensity and duration of rest interval between exercise sets on acute response of RE-induced SPARC secretion. METHODS: We designed two experiments in this study. In study 1, 7 subjects completed three experiments in a random order. They performed two RE at both 70% (High) and 35% (Low) of the individual’s one repetition maximum (1-RM), and stayed rest condition without RE (Rest). The RE consisted of 8 kinds of exercise (double arm curl, shoulder press, double knee extension, chest press, lat-pull down, triceps press down, parallel squat, and seated rowing), for 3 sets of 7 repetitions. We recruited different 7 subjects in study 2, and let them conduct three experiments in a random order: RE (the same 8 kinds of exercise as described in study 1, 16 repetitions × 3 sets at 50% 1-RM) with long inter-set rest interval (LIE, 150 s), RE with short inter-set rest interval (SIE, 50 s), and rest with no-exercise (NE). Blood samples were obtained before, immediate after, and 1h after RE in both study. RESULTS: In study 1, serum SPARC concentration immediately after RE was significantly increased from baseline in High trial (P < 0.05), and that level was significantly higher than those in Rest and Low trials (P < 0.05, in both). In study 2, serum SPARC level immediately after RE in SIE trial significantly elevated compared with baseline (P < 0.05), and the increase was also significantly higher than NE trial (P < 0.05). However, the elevated SPARC concentrations in both High and SIE trials were swiftly returned to baseline within 1 h after RE. CONCLUSIONS: Our findings indicate that RE can induce temporally SPARC secretion. It is also conceivable that increasing exercise load and/or shortening rest intervals between exercise sets during RE might enhance SPARC production.

The Effects of Single versus Multiple Sets of Leg Presses on Myocardial Energy Expenditure

A popular trend in exercise regimes is to maximize the amount of work done in a minimum amount of time or maximize work by minimizing rest intervals. It is hoped that reduced rest time will result in dramatic fitness gains. To date, however, no differences in total energy expenditures have been found between high and low rest interval protocols. Unfortunately, total energy expenditures do reflect the metabolic strain experienced by the cardiac tissue. Rather, the rate pressure product [RPP = Systolic blood pressure × heart rate/1,000] has been recommended as a good index to assess cardiovascular metabolic stress, and to help determine the intensity and duration of exercise in developing fitness. PURPOSE: To determine if cardiac energy expenditure (i.e. RPP) differs between high rest (multiple sets) and low rest (single set) exercise protocols. METHODS: 14 untrained college students (5 male, 9 female; Age: 21.1 ± 0.2 years) participated in the study. Exercise intervention consisted of 2 days of multiple sets (4 sets,10 reps @ 150% body weight, 3 min interset rest) and 2 days of single set (40 reps @ 150% body weight) leg presses, randomly assigned in a balanced crossover order. At least 2 days separated each session and all sets were completed as fast as possible. HR and SBP were obtained on the right arm with an automated blood pressure machine at both pre-exercise and immediate post set completion. A paired T-test was used to compare the difference between the average final post set RPP of two trials of each exercise type. RESULTS: Multiple sets RPP (13.7± 0.8) was significantly less (t=6.5×10-5, p<0.05) than the single set RPP (17.5 ± 0.8). CONCLUSION: Contrary to total body energy expenditure research, a single set of exercise exerts more metabolic stress on the cardiovascular system than doing the same work with several rest intervals. Thus, single set of exercise could be used to train when attempting to train cardiac tissue, but multiple sets of exercise is recommended for people with compromised cardiovascular systems.

Changes in Bench Press Velocity and Power After 8 Weeks of High-Load Cluster- or Traditional-Set Structures.

Davies, TB, Halaki, M, Orr, R, Helms, ER, and Hackett, DA. Changes in bench press velocity and power after 8 weeks of high-load cluster- or traditional-set structures. J Strength Cond Res 34(10): 2734-2742, 2020-This study investigated the effects of high-load cluster- vs. traditional-set structures using the bench press on velocity and power. Twenty-one resistance-trained individuals (male = 12, female = 9) performed a 3-week familiarization block followed by randomization into 1 of 2 upper- and lower-body split training routines performed for 8 weeks. The bench press was the only exercise manipulated with subjects using either cluster-set (CLUS, n = 11) or traditional-set (TRAD, n = 10) structures during training sessions. Subjects performed 4 sets of 5 repetitions at 85% 1 repetition maximum (1RM) with CLUS having a 30-second inter-repetition, and 3-minute interset rest while TRAD had a 5-minute interset rest. A load-velocity profile of relative loads derived from a 1RM test was used to assess velocity and power (absolute and relative to body mass) on the bench press. Significant improvements over time were found across various loads ranging from 45 to 75% 1RM for absolute and relative peak power (p = 0.006-0.041), and mean power (p = 0.001-0.032). Significant decreases over time were found at 55% 1RM and 65% 1RM for peak velocity (p = 0.027 and p = 0.012, respectively) and mean velocity (p = 0.047 and p = 0.022, respectively). There were no significant group or group by time interactions found for all outcomes. Within the context of high-load resistance training, set structure seems to be of less importance for changes in bench press velocity and power provided there is an intention to lift with maximal concentric velocity.

Joint-Level Analyses of the Back Squat With and Without Intraset Rest.

Purpose: To provide a joint-level analysis of traditional (TS) and cluster (CS) set structure during the back-squat exercise. Methods: Eight men (24 [3]y, 177.3 [7.9]cm, 82.7 [11.0]kg, 11.9 [3.5] % body fat, and 150.3 [23.0]kg 1-repetition maximum [1RM]) performed the back-squat exercise (80%1RM) using TS (4 × 6, 2-min interset rest) and CS (4 × [2 × 3], 30-s intraset rest, 90-s interset rest), randomly. Lower-limb kinematics were collected by motion capture, as well as kinetic data by bilateral force platforms. Results: CS attenuated the loss in mean power (TS -21.6% [3.9%]; CS -12.4% [7.5%]; P = .042), although no differences in gross movement pattern (sagittal-plane joint angles) within and between conditions were observed (P ≥ .05). However, joint power produced at the hip increased from repetition (REP) 1 through REP 6 during TS, while a decrease was noted at the knee. A similar pattern was observed in the CS condition but was limited to the hip. Joint power produced at the hip increased from REP 1 through REP 3 but returned to REP 1 values before a similar increase through REP 6, resulting in differences between conditions (REP 4, P = .018; REP 5, P = .022). Conclusions: Sagittal-plane joint angles did not change in either condition, although CS elicited greater power. Differing joint power contributions (hip and knee) suggest potential central mechanism that may contribute to enhanced power output during CS and warrant further study. Practitioners should consider incorporating CS into training to promote greater power adaptations and to mitigate fatigue.

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.

Variability and Impact of Self-Selected Interset Rest Periods During Experienced Strength Training.

We investigated the variability of strength trained athletes' self-selected rest periods between sets of heavy squat training. Sixteen strength-trained male athletes (Mage = 23, SD = 3 years) completed two squat training sessions 48 hours apart. Each training session consisted of five sets of 5RM squats, interspersed with self-selected interset rest periods. A Gymaware linear optical encoder collected kinetic data for each squat and temporal data for each interset rest period. The participants' subjective ratings of the experience were taken before (Readiness to Lift [RTL]) and after (Rating of Perceived Effort [RPE]) each set. Mean total rest time and mean power output differed significantly between sessions. For both sessions, interset rest period increased, and power output decreased between Sets 3, 4, and 5 (95% CI range [-101, -17]) compared with Set 1. In both sessions, RPE increased significantly in Set 3 compared with Set 1 (95% CI range = [0.68, 2.19]), while RTL decreased significantly from Set 3 (95% CI range [-2.99, -0.58]) compared to Set 1. Interset rest period and power output demonstrated fair reliability between sessions (mean intraclass correlation coefficient = 0.55), while RPE and RTL demonstrated good and excellent reliability, respectively (mean intraclass correlation coefficient = 0.63 and 0.80). In conclusion, highly trained strength athletes demonstrated a significant difference in their between session power output and total rest time when using self-selected interset rest periods, despite stability in their subjective ratings of fatigue and effort. Interset rest periods can be self-selected reliably to complete strength training in heavy squat protocol; however, power output may decline during the set.

Acute Effects of Whole-Body Vibration on the Pain Level, Flexibility, and Cardiovascular Responses in Individuals With Metabolic Syndrome.

The aim of the study was to assess the acute effect of whole-body vibration (WBV) exercise, with low frequency (5 Hz), on the pain level (PL), trunk flexibility, and cardiovascular responses (blood pressure [BP] and heart rate [HR]) in individuals with metabolic syndrome (MetS). Forty-four individuals were included in the study (control: 15) or in (WBV exercise: 29) groups. They were submitted to 3 bouts (1 minute each) of WBV exercise (5 Hz and peak-to-peak displacements of 2.5, 5.0, and 7.5 mm, corresponding to peak accelerations of 0.12, 0.25, and 0.35 g, respectively, sitting in a chair with the feet on the platform with knees flexed, followed by 1 minute of interset rest. The Control Group performed the same protocol, but the platform was turned off. The PL was measured through the visual analog pain scale, and the flexibility was measured through the anterior trunk flexion test. Significant improvements on PL (P = .031) and flexibility (P = .004) were found only in the WBV exercise group. The BP and HR remained at physiological levels. In conclusion, the WBV exercise would lead to physiological response decreasing PL and increasing flexibility as well as maintaining the cardiovascular responses in individuals with MetS.

Strength-Endurance Training Reduces the Hamstrings Strength Decline Following Simulated Football Competition in Female Players.

Hamstring strains are the most common injury in multiple sprint sports, with inadequate eccentric hamstring strength and fatigue identified as important risk factors. Resistance training interventions aimed at reducing injury risk typically focus on the development of maximum strength, while little is known about the impact of training on hamstring fatigue resistance. The present study compared the effects of strength endurance (SE) with a strength intervention (S) on the eccentric hamstring strength decline induced by a simulated soccer match. Twenty-one female soccer players were randomly assigned to a S group (n = 10) or a SE group (n = 11). Hamstrings and quadriceps isokinetic concentric and eccentric peak torque (PT) were assessed at 120°.s-1 and hamstrings-to-quadriceps ratio (HEcc:QCon) calculated, pre- and immediately post a 90-min simulated match (BEAST90). This was repeated following a 7-week intervention of either three to five sets of 6RM leg curl and stiff-leg deadlift with 3-min inter-set rest (S), or the same exercises performed using three sets of 12–20 RM with 45–90 s inter-set rest (SE). At baseline, the simulated match led to significant declines in hamstrings eccentric peak torque (EccPT) in both groups in both dominant (D) and non-dominant (ND) legs [SE: (D: -15.5, ND: -15.6%), P = 0.001 to 0.016; S: (D: -12.3%, ND: -15.5%), P = 0.001 to 0.018]. After the 7-week intervention, we observed a group∗intervention∗match interaction such that there was no significant decline in EccPT in the SE group following the simulated match (D: 5.3%, ND: 2.0%), but there remained significant declines in the S group (D: -14.2%, ND: -15.5%, P = 0.018–0.001). Similarly, in the SE group, there was a significant decrease in the HEcc:QCon in D before (-14.2%, P = 0.007), but not after the training intervention, whereas declines were observed in the S group both at baseline, and following the intervention (D: -13.9%, ND: -15.6%, P = 0.045). These results demonstrate that SE training can reduce the magnitude of the EccPT decline observed during soccer competition. As inadequate eccentric strength and fatigue are both risk factors for hamstring injury, SE training should be considered along with the development of peak eccentric strength, as a component of programs aimed at reducing injury risk in multiple-sprint sports.

Hypoxia During Resistance Exercise Does Not Affect Physical Performance, Perceptual Responses, or Neuromuscular Recovery.

Scott, BR, Slattery, KM, Sculley, DV, and Dascombe, BJ. Hypoxia during resistance exercise does not affect physical performance, perceptual responses, or neuromuscular recovery. J Strength Cond Res 32(8): 2174-2182, 2018-This study aimed to determine whether performing resistance exercise in hypoxia affects markers of physical performance, perceptual responses, and neuromuscular function. Fourteen male subjects (age: 24.6 ± 2.7 years; height: 179.7 ± 5.9 cm; body mass: 84.6 ± 11.6 kg) with >2 years resistance training experience performed moderate-load resistance exercise in 2 conditions: normoxia (FIO2 = 0.21) and hypoxia (FIO2 = 0.16). Resistance exercise comprised 3 sets of 10 repetitions of back squats and deadlifts at 60% of 1 repetition maximum (1RM), with 60 seconds inter-set rest. Physical performance was assessed by quantifying velocity and power variables during all repetitions. Perceptual ratings of perceived exertion, physical fatigue, muscle soreness, and overall well-being were obtained during and after exercise. Neuromuscular performance was assessed by vertical jump and isometric mid-thigh pull (IMTP) tasks for up to 48 hours after exercise. Although physical performance declined across sets, there were no differences between conditions. Similarly, perceived exertion and fatigue scores were not different between conditions. Muscle soreness increased from baseline at 24 and 48 hours after exercise in both conditions (p ≤ 0.001). Jump height and IMTP peak force were decreased from baseline immediately after exercise (p ≤ 0.026), but returned to preexercise values after 24 hours. These findings suggest that hypoxic resistance exercise does not affect exercise performance or perceived exercise intensity. In addition, neuromuscular recovery and perceptual markers of training stress were not affected by hypoxia, suggesting that hypoxic resistance training may not add substantially to the training dose experienced.