The ASSIST trial: Acute effects of manipulating strength exercise volume on insulin sensitivity in obese adults: A protocol for a randomized controlled, crossover, clinical trial.

Type 2 diabetes mellitus is a disease in which insulin action is impaired, and an acute bout of strength exercise can improve insulin sensitivity. Current guidelines for strength exercise prescription suggest that 8 to 30 sets could be performed, although it is not known how variations in exercise volume impact insulin sensitivity. Additionally, this means an almost 4-fold difference in time commitment, which might directly impact an individual's motivation and perceived capacity to exercise. This study will assess the acute effects of high- and low-volume strength exercise sessions on insulin sensitivity. After being thoroughly familiarized, 14 obese individuals of both sexes (>40 year old) will undergo 3 random experimental sessions, with a minimum 4-day washout period between them: a high-volume session (7 exercises, 3 sets per exercise, 21 total sets); a low-volume session (7 exercises, 1 set per exercise, 7 total sets); and a control session, where no exercise will be performed. Psychological assessments (feeling, enjoyment, and self-efficacy) will be performed after the sessions. All sessions will be held at night, and the next morning, an oral glucose tolerance test will be performed in a local laboratory, from which indexes of insulin sensitivity will be derived. We believe this study will aid in strength exercise prescription for individuals who claim not to have time to exercise or who perceive high-volume strength exercise intimidating to adhere to. This trial was prospectively registered (ReBEC #RBR-3vj5dc5 https://ensaiosclinicos.gov.br/rg/RBR-3vj5dc5).

Randomized Controlled Trial to Study the Acute Effects of Strength Exercise on Insulin Sensitivity in Obese Adults.

An acute session of strength exercise (SE) ameliorates insulin sensitivity (IS) for several hours; however, the effects of SE volume (i.e., number of sets) have not been studied thoroughly. Although it is intuitive that some SE is better than none, and more is better than some for the improvement of IS, high-volume sessions might be challenging for diseased populations to complete, especially obese adults, for whom even a brisk walk can be challenging. This protocol details a randomized clinical trial to assess the acute effects of SE on IS in obese adults. The inclusion criteria are body mass index >30 kg/m2, central obesity (waist circumference >88 cm and >102 cm for women and men, respectively), and age >40 years. Participants will be familiarized with the SE (7 exercises targeting major muscle groups) and then will perform three sessions in a randomized order: session 1 - high-volume session (3 sets/exercise); session 2 - low-volume session (1 set/exercise); session 3 - control session (no exercise). Diet will be controlled the day before and on the day of the sessions. Sessions will be completed at night, and an oral glucose tolerance test will be performed the next morning, from which several indexes of IS will be derived, such as the area under the curve (AUC) of glucose and insulin, the Matsuda index, the Cederholm index, the muscle IS index, and the Gutt index. Based on pilot studies, we expect ~15% improvement in IS (insulin AUC, and Matsuda and Cederholm indexes) after the high-volume session, and ~8% improvement after the low-volume session compared to the control session. This study will benefit individuals who find high-volume SE sessions challenging but still aim to improve their IS by investing 1/3 of their time and effort.

Simultaneous Upper- and Lower-Limb Postactivation Performance Enhancement After Clean and Jerk.

Studies on postactivation performance enhancement (PAPE) have used different exercises as a conditioning activity to investigate potentiation, but exclusively in upper limbs (UL) or lower (LL) limbs, or contralateral potentiation. A single exercise capable of inducing PAPE in both UL and LL is currently unknown. The present study explored the effect of the clean and jerk (C&J) as a conditioning activity for simultaneously producing PAPE interlimbs at the fourth, seventh, and 12th minutes postintervention. Twelve male weightlifters with 1-repetition maximum (1RM) in the C&J equivalent to ≥1.15 × body mass were randomly submitted to 2 experimental conditions (C&J and control [CON]). The C&J condition consisted of general warm-up (running on a treadmill and self-selected preparatory exercises) and 4 sets of 3 repetitions of C&J with 2 minutes between them (30%1RM, 50%1RM, 65%1RM, and 80%1RM) followed by a countermovement jump and a bench-press throw on a Smith machine after 4, 7, and 12 minutes, to measure the magnitude of PAPE in UL and LL. No previous exercise preceded countermovement-jump and bench-press-throw tests in the CON besides general warm-up. The main finding was that, regardless of time, the C&J resulted in greater height on countermovement jump and Smith machine bench-press throw when compared with the CON, presenting a similar effect size between UL and LL (34.6 [3.9] vs 33.4 [4.1] cm [+3.66%]; P = .038; effect size = 0.30 and 30.3 [4.7] vs 29.0 [5.1] cm [+4.44%]; P = .039; effect size = 0.26), respectively. Thus, C&J can be useful to produce PAPE simultaneously among members.

Efeitos da dor experimental no desempenho dos músculos flexores do cotovelo após oito semanas de treinamento de força: um estudo piloto / Effects of experimental pain on elbow flexor muscles performance after eight weeks of strength training: a pilot study

INTRODUÇÃO: O treinamento de força tem sido recomendado na reabilitação clínica, bem como no condicionamento físico de atletas. Não é incomum, em ambos os casos, a presença de dor durante a prática; no entanto, até o momento, não há informação consensual em relação aos efeitos da dor muscular aguda nas adaptações ao treinamento de força. OBJETIVO: O objetivo deste estudo piloto foi avaliar os efeitos da dor induzida experimentalmente na adaptação da força muscular após um período de treinamento de 8 semanas. MÉTODO: O estudo incluiu cinco voluntários saudáveis do sexo masculino e não treinados. Os participantes foram submetidos a um protocolo de treinamento de força (3x/semana durante 8 semanas) para os músculos flexores do cotovelo. A dor muscular aguda foi induzida no início de cada sessão de treinamento, por meio de infusão intramuscular de 2,5 ml de solução salina hipertônica (6%) no ventre do músculo bíceps braquial. A força dinâmica máxima (1RM) e a contração isométrica voluntária máxima (CIVM) foram medidas antes e após quatro e oito semanas de treinamento. RESULTADOS: A força dinâmica máxima aumentou, em média, 37,3% e 78,4% após quatro e oito semanas, respectivamente. Entretanto, pouca ou nenhuma diferença foi encontrada na CIVM (-1,7% e -3,0% após quatro e oito semanas, respectivamente). CONCLUSÃO: Após 24 sessões de treinamento de força, com dor muscular aguda induzida a cada sessão, voluntários saudáveis aumentaram sua capacidade de produzir força dinâmica máxima em mais de 75%; entretanto, a força isométrica apresentou apenas pequenas variações negativas.

INTRODUCTION: Strength training has been recommended in clinical rehabilitation, as well as in the physical conditioning of athletes. It is not uncommon, in both cases, the presence of pain during practice; however, to date, there is no consensual information about the effects of acute muscle pain on strength training adaptations. OBJECTIVE: The aim of this pilot study was to evaluate the effects of experimentally induced pain on muscle strength adaptation after an 8-week training period. METHOD: The study included five untrained, healthy male volunteers. Participants were submitted to a strength training protocol (3x/week for 8 weeks) for the elbow flexor muscles. Acute muscle pain was induced at the beginning of each training session through an intramuscular infusion of 2.5 ml of hypertonic saline (6%) into the biceps brachii muscle belly. Maximal dynamic strength (1RM) and maximal voluntary isometric contraction (MVIC) were measured at pre- and after four and eight weeks of training. RESULTS: Maximal dynamic strength increased, on average, 37.3% and 78.4% after four and eight weeks, respectively. However, little, if any, difference was found in MVIC (-1.7% and ­ 3.0% after four and eight weeks, respectively). CONCLUSION: After 24 strength training sessions, with acute muscle pain induced every session, healthy volunteers increased their ability to produce maximal dynamic strength by more than 75%; however, isometric strength presented only small negative changes.

Can plyometric training change the pacing behaviour during 10-km running?

The effects of plyometric training (PT) on middle- and long-distance running performances are well established. However, its influence on pacing behaviour is still unclear. The aim of this study was to evaluate the effects of PT on pacing behaviour. In addition, verify whether the adaptations induced by PT would change ratings of perceived exertion (RPE) and/or affective feelings during the race. Twenty-eight male runners were assigned to two groups: control (C) and PT. PT held two weekly PT sessions for eight weeks. Drop jump (DJ) performance, 10-km running performance, pacing behaviour, RPE and affective feelings, VO2peak, ventilatory thresholds (VT1 and VT2), peak treadmill speed (PTS), and running economy (RE) were measured. For group comparisons, a mixed model analysis for repeated measures, effect size (ES) and 90% confidence interval (90% CI) were calculated for all dependent variables. Significant differences pre-to-post was observed for PT group in DP (7.2%; p ≤ 0.01; ES = 0.56 (0.28-0.85)) and RE (4.5%; p ≤ 0.05; ES = -0.52 ((-0.73 to -0.31)) without changes in pacing behaviour. While PT was effective for improving DJ and RE, there is no evidence that pacing behaviour, RPE or affective feelings are directly affected by these adaptations during a 10-km time trial run.

Low-Load Resistance Exercise with Blood Flow Restriction Increases Hypoxia-Induced Angiogenic Genes Expression.

The aim of the study was to determine whether low-load exercise (LL) with blood flow restriction (LL-BFR) would induce similar changes in expression of genes involved in hypoxia and angiogenesis compared to LL and high-load exercise (HL). Twenty-four males (age: 21.3 ± 1.9 years, body height: 1.74 ± 0.8 m, body mass: 73 ± 1.8 kg) were allocated into three groups: low-load exercise (LL), low-load exercise with blood-flow restriction (LL-BFR), and high-load exercise (HL). For the LL-BFR group a pneumatic cuff was inflated at 80% of the arterial occlusion pressure. All participants performed bilateral knee extension exercise, twice a week, for 8 weeks. LL and LL-BFR groups performed 3-4 sets of 15 reps at 20% 1RM, whilst the HL group performed 3-4 sets of 8-10 reps at 80% 1RM with a 60-s rest interval between sets. The hypoxia-inducible factor-1 alpha (HIF-1α) and beta (HIF-1ß), vascular endothelial growth factor (VEGF), neuronal (nNOS), and inducible nitric oxide synthase (iNOS) genes expression were assessed before and after training. HIF-1α and HIF-1ß mRNA levels significantly increased in the LL-BFR group and exceeded those elicited by HL and LL groups (p < .0001). VEGF gene expression was increased in both LL-BFR and HL groups, however, LL-BFR elicited a greater increase than LL (p < .0001). nNOS and iNOS genes expression significantly increased in all groups with greatest increases being observed in the LL-BFR group (p < .0001). The findings suggest that LL-BFR induces greater increases in genes expression related to hypoxia and angiogenesis than traditional resistance training.

Effect of different training frequencies on maximal strength performance and muscle hypertrophy in trained individuals-a within-subject design.

Several studies comparing resistance training (RT) frequencies may have been affected by the large between-subject variability. This study aimed to compare the changes in lower limbs maximal dynamic strength (1RM) and quadriceps femoris cross-sectional area (CSA) after a RT with different weekly frequencies in strength-trained individuals using a within-subject design. Twenty-four men participated in a 9-week RT program, being randomly divided into two conditions: resistance training with equalized total training volume (RTEV) and with unequalized total training volume (RTUV). The RT protocol used the unilateral leg press 45° exercise and each subject's lower limb executed one of the proposed frequencies (one and three times/week). All conditions effectively increased 1RM and CSA (p<0.001); however, no significant differences were observed in the values of 1RM (p = 0.454) and CSA (p = 0.310) between the RT frequencies in the RTEV and RTUV conditions. Therefore, RT performed three times a week showed similar increases in 1RM and CSA to the program performed once a week, regardless of training volume equalization. Nevertheless, when the higher RT frequency allowed the application of a greater TTV (i.e., RTUV), higher effect size (ES) values (0.51 and 0.63, 1RM and CSA, respectively) were observed for the adaptations.

Effects of the association of different volumes of strength training with photobiomodulation therapy on insulin resistance: A protocol for a randomized, triple-blind, placebo-controlled trial.

Background: Insulin resistance (IR) is the main risk factor for developing type 2 diabetes. Both strength training (ST) and photobiomodulation therapy (PBMt) reduce IR, but the effect of combining different volumes of ST with PBMt is unknown. Methods: Overweight/obese individuals will be assigned to 4 groups (n = 12/group): ST with volume following international guidelines (3 sets per exercise - high volume) or one-third of this volume (1 set per exercise - low volume), combined with PBMt or placebo. ST will be performed for 20 sessions over 10 weeks and will consist of 7 exercises. The PBMt will be applied after training sessions using blankets with light emitters (LEDs) placed over the skin on the frontal and the posterior region of the body, following the parameters recommended by the literature. The placebo group will undergo an identical procedure, but blankets will emit insignificant light. To measure plasma glucose and insulin concentrations, oral glucose tolerance tests (OGTT) will be performed before and after the training period. Thereafter, IR, the area under the curve of glucose and insulin, and OGTT-derived indices of insulin sensitivity/resistance will be calculated. Expected impact on the field: This study will determine the effects of different ST volumes on IR and whether the addition of PBMt potentiates the effects of ST. Because previously sedentary, obese, insulin-resistant individuals might not comply with recommended volumes of exercise, the possibility that adding PBMt to low-volume ST enhances ST effects on IR bears practical significance.

Blood-Flow-Restriction-Training-Induced Hormonal Response is not Associated with Gains in Muscle Size and Strength.

The aim of this study was to determine whether increases in post-exercise endocrine response to low-load resistance exercise with blood flow restriction and high-load resistance exercise would have association with increases in muscle size and strength after an 8-week training period. Twenty-nine untrained men were randomly allocated into three groups: low-load resistance exercise with (LL-BFR) or without blood flow restriction (LL), and high-load resistance exercise (HL). Participants from LL-BFR and LL groups performed leg extension exercise at 20% of one repetition maximum (1RM), four sets of 15 repetitions and the HL group performed four sets of eight repetitions at 80% 1RM. Before the first training session, growth hormone (GH), insulin-like growth factor 1 (IGF-1), testosterone, cortisol, and lactate concentration were measured at rest and 15 min after the exercise. Quadriceps CSA and 1RM knee extension were assessed at baseline and after an 8-week training period. GH increased 15 min after exercise in the LL-BFR (p = 0.032) and HL (p < 0.001) groups, with GH concentration in the HL group being higher than in the LL group (p = 0.010). There was a time effect for a decrease in testosterone (p = 0.042) and an increase in cortisol (p = 0.005), while IGF-1 remained unchanged (p = 0.346). Both muscle size and strength were increased after training in LL-BFR and HL groups, however, these changes were not associated with the acute post-exercise hormone levels (p > 0.05). Our data suggest that other mechanisms than the acute post-exercise increase in systemic hormones induced by LL-BFR and HL produce changes in muscle size and strength.

Weightlifting derivatives vs. plyometric exercises: Effects on unloaded and loaded vertical jumps and sprint performance.

The aim of this study was to compare the effects of weightlifting derivatives (WL) and plyometric exercises (PLYO) on unloaded and loaded vertical jumps and sprint performance. Initially, 45 resistance-trained men underwent a 4-week WL learning period. Then, the participants were randomly assigned to 1 of 3 groups (WL (n = 15), PLYO (n = 15), and control group (CG) (n = 15)) and followed a training period of 8 weeks. The WL group performed exercises to stimulate the entire force-velocity profile, while the PLYO group performed exercises with an emphasis in vertical- and horizontal-oriented. The CG did not perform any exercise. Pre- and post-training assessments included peak power output (PPO) and jump height (JH) in the squat jump (SJ), countermovement jump (CMJ), CMJ with 60% and 80% of the body mass (CMJ60% and CMJ80%, respectively), and mean sprinting speeds over 5, 10, 20, and 30 m distances. From pre- to post-training, PLYO significantly increased (p≤0.05) PPO and JH in the SJ, PPO during CMJ, and PPO and JH in the CMJ60%; however, no significant changes were observed in JH during CMJ, and PPO and JH in the CMJ80%. For WL and CG, no significant changes were observed in the unloaded and loaded vertical jumps variables. PLYO also resulted in significant improvements (p≤0.05) for 5, 10, and 20 m sprint speeds, but not for 30 m. For WL and CG, no significant changes were observed for all sprint speeds. In conclusion, these data demonstrate that PLYO was more effective than a technically-oriented WL program to improve unloaded and loaded vertical jumps and sprint performance.

Volume Load Rather Than Resting Interval Influences Muscle Hypertrophy During High-Intensity Resistance Training.

ABSTRACT: Longo, AR, Silva-Batista, C, Pedroso, K, de Salles Painelli, V, Lasevicius, T, Schoenfeld, BJ, Aihara, AY, de Almeida Peres, B, Tricoli, V, and Teixeira, EL. Volume load rather than resting interval influences muscle hypertrophy during high-intensity resistance training. J Strength Cond Res 36(6): 1554-1559, 2022-Interset rest interval has been proposed as an important variable for inducing muscle mass and strength increases during resistance training. However, its influence remains unclear, especially when protocols with differing intervals have equalized volume. We aimed to compare the effects of long (LI) vs. short rest interval (SI) on muscle strength (one repetition maximum [1RM]) and quadriceps cross-sectional area (QCSA), with or without equalized volume load (VL). Twenty-eight subjects trained twice a week for 10 weeks. Each subject's leg was allocated to 1 of 4 unilateral knee extension protocols: LI, SI, SI with VL -matched by LI (VLI-SI), and LI with VL-matched by SI (VSI-LI). A 3-minute rest interval was afforded in LI and VSI-LI protocols, while SI and VLI-SI employed a 1-minute interval. All subjects trained with a load corresponding to 80% 1RM. One repetition maximum and QCSA were measured before and after training. All protocols significantly increased 1RM values in post-training (p < 0.0001; LI: 27.6%, effect size [ES] = 0.90; VLI-SI: 31.1%, ES = 1.00; SI: 26.5%, ES = 1.11; and VSI-LI: 31.2%, ES = 1.28), with no significant differences between protocols. Quadriceps cross-sectional area increased significantly for all protocols in post-training (p < 0.0001). However, absolute changes in QCSA were significantly greater in LI and VLI-SI (13.1%, ES: 0.66 and 12.9%, ES: 0.63) than SI and VSI-LI (6.8%, ES: 0.38 and 6.6%, ES: 0.37) (both comparisons, p < 0.05). These data suggest that maintenance of high loads is more important for strength increases, while a greater VL plays a primary role for hypertrophy, regardless of interset rest interval.

The Effect of Low-intensity Aerobic Training Combined with Blood Flow Restriction on Maximal Strength, Muscle Mass, and Cycling Performance in a Cyclist with Knee Displacement.

Low-intensity aerobic training combined with blood flow restriction (LI + BFR) has resulted in increases in aerobic and neuromuscular capacities in untrained individuals. This strategy may help cyclists incapable of training with high intensity bouts or during a rehabilitation program. However, there is a lack of evidence about the use of LI + BFR in injured trained cyclists. Thus, we investigated the effects of LI + BFR on aerobic capacity, maximal isometric strength, cross-sectional area of vastus lateralis (CSAVL), time to exhaustion test (TTE), and 20 km cycling time-trial performance (TT20 km) in a male cyclist with knee osteoarthritis (OA). After a 4-week control period, a 9-week (2 days/week) intervention period started. Pre- and post-intervention TT20 km, peak oxygen consumption (VO2peak), power output of the 1st and 2nd ventilatory thresholds (1st WVT and 2nd WVT), maximum power output (Wmax), TTE, muscle strength and CSAVL of both legs were measured. Training intensity was fixed at 30% of Wmax while the duration was progressively increased from 12 min to 24 min. There was a reduction in time to complete TT20 km (-1%) with increases in TT20 km mean power output (3.9%), VO2peak (11.4%), 2nd WVT (8.3%), Wmax (3.8%), TTE (15.5%), right and left legs maximal strength (1.3% and 8.5%, respectively) and CSAVL (3.3% and 3.7%, respectively). There was no alteration in 1st WVT. Based on the results, we suggest that LI + BFR may be a promising training strategy to improve the performance of knee-injured cyclists with knee OA.

Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training.

ABSTRACT: Lasevicius, T, Schoenfeld, BJ, Silva-Batista, C, Barros, TdS, Aihara, AY, Brendon, H, Longo, AR, Tricoli, V, Peres, BdA, and Teixeira, EL. Muscle failure promotes greater muscle hypertrophy in low-load but not in high-load resistance training. J Strength Cond Res 36(2): 346-351, 2022-The purpose of this study was to investigate the effects of an 8-week resistance training program at low and high loads performed with and without achieving muscle failure on muscle strength and hypertrophy. Twenty-five untrained men participated in the 8-week study. Each lower limb was allocated to 1 of 4 unilateral knee extension protocols: repetitions to failure with low load (LL-RF; ∼34.4 repetitions); repetitions to failure with high load (HL-RF; ∼12.4 repetitions); repetitions not to failure with low load (LL-RNF; ∼19.6 repetitions); and repetitions not to failure with high load (HL-RNF; ∼6.7 repetitions). All conditions performed 3 sets with total training volume equated between conditions. The HL-RF and HL-RNF protocols used a load corresponding to 80% 1 repetition maximum (RM), while LL-RF and LL-RNF trained at 30% 1RM. Muscle strength (1RM) and quadriceps cross-sectional area (CSA) were assessed before and after intervention. Results showed that 1RM changes were significantly higher for HL-RF (33.8%, effect size [ES]: 1.24) and HL-RNF (33.4%, ES: 1.25) in the post-test when compared with the LL-RF and LL-RNF protocols (17.7%, ES: 0.82 and 15.8%, ES: 0.89, respectively). Quadriceps CSA increased significantly for HL-RF (8.1%, ES: 0.57), HL-RNF (7.7%, ES: 0.60), and LL-RF (7.8%, ES: 0.45), whereas no significant changes were observed in the LL-RNF (2.8%, ES: 0.15). We conclude that when training with low loads, training with a high level of effort seems to have greater importance than total training volume in the accretion of muscle mass, whereas for high load training, muscle failure does not promote any additional benefits. Consistent with previous research, muscle strength gains are superior when using heavier loads.

Session Rating of Perceived Exertion as an Efficient Tool for Individualized Resistance Training Progression.

ABSTRACT: Gomes, RL, Lixandrão, ME, Ugrinowitsch, C, Moreira, A, Tricoli, V, and Roschel, H. Session rating of perceived exertion as an efficient tool for individualized resistance training progression. J Strength Cond Res 36(4): 971-976, 2022-The present study aimed to investigate the effects of an individualized resistance training (RT) progression model based on the session rating of perceived exertion (RPE) on gains in muscle mass and strength when compared with a conventional predetermined progression method (PP). Twenty previously trained young male subjects were randomly allocated to 1 of the 2 groups: RPE (n = 10) or PP (n = 10). Muscle cross-sectional area (CSA) and maximum dynamic strength were assessed at baseline and after 6 weeks. The RPE-based progression model resulted in a lower number of high-intensity sessions compared with the PP-based model. Despite this, both groups showed significant and similar increases in CSA (p < 0.0001; RPE = 6.55 ± 5.27% and PP = 9.65 ± 3.63%) and strength (p < 0.0001; RPE = 9.68 ± 4.57% and PP = 9.28 ± 4.01%) after the intervention period. No significant between-group difference was observed for total training volume (RPE = 45,366.00 ± 10,190.00 kg and PP = 47,779.00 ± 5,685.00 kg; p = 0.52). Our results showed that an RT progression model based on session-to-session physiological response assessments resulted in fewer high-intensity training sessions while allowing for similar gains in muscle strength and mass. Thus, trainees are encouraged to adopt session RPE as a potential tool to control workload progression throughout a training period and allowing the optimization of training stimulus on an individual basis.

Perceptual and Neuromuscular Responses Adapt Similarly Between High-Load Resistance Training and Low-Load Resistance Training With Blood Flow Restriction.

ABSTRACT: Teixeira, EL, Painelli, VdS, Schoenfeld, BJ, Silva-Batista, C, Longo, AR, Aihara, AY, Cardoso, FN, Peres, BdA, and Tricoli, V. Perceptual and neuromuscular responses adapt similarly between high-load resistance training and low-load resistance training with blood flow restriction. J Strength Cond Res 36(9): 2410-2416, 2022-This study compared the effects of 8 weeks of low-load resistance training with blood flow restriction (LL-BFR) and high-load resistance training (HL-RT) on perceptual responses (rating of perceived exertion [RPE] and pain), quadriceps cross-sectional area (QCSA), and muscle strength (1 repetition maximum [RM]). Sixteen physically active men trained twice per week, for 8 weeks. One leg performed LL-BFR (3 sets of 15 repetitions, 20% 1RM), whereas the contralateral leg performed HL-RT (3 sets of 8 repetitions, 70% 1RM). Rating of perceived exertion and pain were evaluated immediately after the first and last training sessions, whereas QCSA and 1RM were assessed at baseline and after training. Rating of perceived exertion was significantly lower (6.8 ± 1.1 vs. 8.1 ± 0.8, p = 0.001) and pain significantly higher (7.1 ± 1.2 vs. 5.8 ± 1.8, p = 0.02) for LL-BFR than that for HL-RT before training. Significant reductions in RPE and pain were shown for both protocols after training (both p < 0.0001), although no between-protocol differences were shown in absolute changes ( p = 0.10 and p = 0.48, respectively). Both LL-BFR and HL-RT were similarly effective in increasing QCSA (7.0 ± 3.8% and 6.3 ± 4.1%, respectively; both p < 0.0001) and 1RM (6.9 ± 4.1% and 13.7 ± 5.9%, respectively; both P < 0.0001), although absolute changes for 1RM in HL-RT were greater than LL-BFR ( p = 0.001). In conclusion, LL-BFR produces lower RPE values and a higher pain perception than HL-RT. However, consistent application of these approaches result in chronic adaptations so that there are no differences in perceptual responses over the course of time. In addition, muscle strength is optimized with HL-RT despite similar increases in muscle hypertrophy between conditions.

Blood Flow Restriction Does Not Promote Additional Effects on Muscle Adaptations When Combined With High-Load Resistance Training Regardless of Blood Flow Restriction Protocol.

ABSTRACT: Teixeira, EL, Ugrinowitsch, C, de Salles Painelli, V, Silva-Batista, C, Aihara, AY, Cardoso, FN, Roschel, H, and Tricoli, V. Blood flow restriction does not promote additional effects on muscle adaptations when combined with high-load resistance training regardless of blood flow restriction protocol. J Strength Cond Res 35(5): 1194-1200, 2021-The aim of this study was to investigate, during high-load resistance training (HL-RT), the effect of blood flow restriction (BFR) applied during rest intervals (BFR-I) and muscle contractions (BFR-C) compared with HL-RT alone (no BFR), on maximum voluntary isometric contraction (MVIC), maximum dynamic strength (one repetition maximum [1RM]), quadriceps cross-sectional area (QCSA), blood lactate concentration ([La]), and root mean square of the surface electromyography (RMS-EMG) responses. Forty-nine healthy and untrained men (25 ± 6.2 years, 178.1 ± 5.3 cm and 78.8 ± 11.6 kg) trained twice per week, for 8 weeks. One leg of each subject performed HL-RT without BFR (HL-RT), whereas the contralateral leg was randomly allocated to 1 of 2 unilateral knee extension protocols: BFR-I or BFR-C (for all protocols, 3 × 8 repetitions, 70% 1RM). Maximum voluntary isometric contraction, 1RM, QCSA, and acute changes in [La] and RMS-EMG were assessed before and after training. The measurement of [La] and RMS-EMG was performed during the control sessions with the same relative load obtained after the 1RM test, before and after training. Similar increases in MVIC, 1RM, and QCSA were demonstrated among all conditions, with no significant difference between them. [La] increased for all protocols in pre-training and post-training, but it was higher for BFR-I compared with the remaining protocols. Increases in RMS-EMG occurred for all protocols in pre-training and post-training, with no significant difference between them. In conclusion, despite of a greater metabolic stress, BFR inclusion to HL-RT during rest intervals or muscle contraction did not promote any additive effect on muscle strength and hypertrophy.

Self-selected Rest Interval Improves Vertical Jump Postactivation Potentiation.

ABSTRACT: do Carmo, EC, De Souza, EO, Roschel, H, Kobal, R, Ramos, H, Gil, S, and Tricoli, V. Self-selected rest interval improves vertical jump postactivation potentiation. J Strength Cond Res 35(1): 91-96, 2021-This study compared the effects of self-selected rest interval (SSRI) and fixed rest interval (FRI) strategies on postactivation potentiation (PAP) in countermovement jump (CMJ) performance. Twelve strength-trained men (age: 25.4 ± 3.6 years; body mass: 78.8 ± 10.5 kg; height: 175 ± 7.0 cm; half-squat 1 repetition maximum: 188.7 ± 33.4 kg) performed 3 experimental conditions: (a) FRI: CMJ test; 4-minute rest interval; 5 repetition maximum (5RM) back squat; 4-minute rest interval; and CMJ test, (b) SSRI: CMJ test; 4-minute rest interval; 5RM back squat; SSRI; and CMJ test, and (c) control: CMJ test; 8-minute rest interval and CMJ test. In SSRI, subjects were instructed to rest until they felt fully recovered and able to exercise at maximal intensity based on the perceived readiness scale. Significant changes in pre-post CMJ performance were observed in the SSRI condition (38.2 ± 4.6 cm vs. 40.5 ± 4.4 cm; p = 0.08; confidence interval [CI]: 0.72-3.82 cm; effect size [ES] = 0.93). There were significant differences in post-CMJ performance when SSRI was compared with FRI (40.5 ± 4.4 cm vs. 37.7 ± 5.1 cm; p = 0.02; CI: 0.43-5.08; ES = 1.13) and control (40.5 ± 4.4 cm vs. 37.4 ± 5.7 cm; p = 0.01; CI: 0.66-5.61; ES = 1.35). The average rest interval length for the SSRI condition was 5:57 ± 2:44 min:sec (CI: 4:24-7:30). Our results suggest that the use of SSRI was an efficient and practical strategy to elicit PAP on CMJ height in strength-trained individuals.

Blood Pressure Increase in Hypertensive Individuals During Resistance Training Protocols With Equated Work to Rest Ratio.

Introduction: Despite growing evidence regarding the benefits of resistance training in hypertension, the large and abrupt rise of systolic blood pressure (SBP) observed during resistance exercise execution has resulted in concern about its safety. However, the manipulation of the resistance training protocol (RTP) organization, maintaining the work to rest ratio equated between protocols (W:R-equated), may reduce the SBP increase. Purpose: To compare cardiovascular responses during two W:R-equated RTPs (3 × 15:88 s vs. 9 × 5:22 s - sets × reps: rest between sets) performed in exercises for the lower and upper limbs. Methods: Twelve medicated hypertensives (48 ± 8 years) randomly performed two RTPs in the bilateral leg extension (BLE) and unilateral elbow flexion (UEF) exercises at 50% 1RM. Increases (Δ) of SBP, heart rate (HR) and rate pressure product (RPP) during the exercises were measured by photoplethysmography. Results: In both BLE and UEF exercises, Δ SBP was significantly greater during 3 × 15:88 s than 9 × 5:22 s (peak values: BLE = + 84 ± 39 vs. + 67 ± 20 mm Hg, and UEF = + 46 ± 25 vs. + 37 ± 18 mm Hg, respectively, both p < 0.05). ΔHR and ΔRPP were significantly higher in the 3 × 15:88 s than 9 × 5:22 s in BLE (peak values + 45 ± 17 vs. + 30 ± 8 bpm, and + 15,559 ± 5570 vs. + 10,483 ± 2614 mm Hg. bpm). Conclusion: In medicated hypertensives, a RTP combining more sets with less repetitions per set and shorter rest intervals between sets (i.e., 9 × 5:22 s) produced a smaller increase in cardiovascular load (ΔSBP, ΔHR and ΔRPP) during its execution than a protocol with fewer longer sets (i.e., 3 × 15:88 s).

Affective Feelings and Perceived Exertion During a 10-km Time Trial and Head-to-Head Running Race.

PURPOSE: To verify the affective feelings (AFs) and rating of perceived exertion (RPE) responses during a 10-km competitive head-to-head (HTH) running race and compare them with a time-trial (TT) running race. METHODS: Fourteen male runners completed 2 × 10-km runs (TT and HTH) on different days. Speed, RPE, and AF were measured every 400 m. For pacing analysis, races were divided into the following 4 stages: first 400 m (F400), 401-5000 m (M1), 5001-9600 m (M2), and the last 400 m (final sprint). RESULTS: Improvement of performance was observed (39:32 [02:41] min:s vs 40:28 [02:55] min:s; P = .03; effect size = -0.32) in HTH compared with TT. There were no differences in either pacing strategy or RPE between conditions. AFs were higher during the HTH, being different in M2 compared with TT (2.09 [1.81] vs 0.22 [2.25]; P = .02; effect size = 0.84). CONCLUSIONS: AFs are directly influenced by the presence of opponents during an HTH race, and a more positive AF could be involved in the dissociation between RPE and running speed and, consequently, the overall race performance.