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.

Strength Training with Repetitions to Failure does not Provide Additional Strength and Muscle Hypertrophy Gains in Young Women.

This study investigated the effects of a 10-week resistance training to failure on neuromuscular adaptations in young women. Eighty-nine active young women were randomly assigned to one of three groups: 1) repetitions to failure (RF; three sets of repetitions to failure); 2) repetitions not to failure with equalized volume (RNFV; four sets of 7 repetitions); and 3) repetitions not to failure (RNF; three sets of 7 repetitions). All groups performed the elbow flexor exercise (bilateral biceps curl) and trained 2 days per week using 70% of 1RM. There were significant increases (p<0.05) in muscle strength after 5 (15.9% for RF, 18.4% for RNF, and 19.9% for RNFV) and 10 (28.3% for RF, 26.8% for RNF, and 28.3% for RNFV) weeks of training, with no significant differences between groups. Additionally, muscular endurance increased after 5 and 10 weeks, with no differences between groups. However, peak torque (PT) increased significantly at 180°.s-1 in the RNFV (13.7%) and RNF (4.1%) groups (p<0.05), whereas no changes were observed in the RF group (-0.5%). Muscle thickness increased significantly (p<0.05) in the RF and RNFV groups after 5 (RF: 8.4% and RNFV: 2.3%) and 10 weeks of training (RF: 17.5%, and RNFV: 8.5%), whereas no significant changes were observed in the RNF group (3.9 and 2.1% after 5 and 10 weeks, respectively). These data suggest that short-term training of repetitions to failure do not yield additional overall neuromuscular improvements in young women.

Lower-extremity isokinetic strength ratios of elite springboard and platform diving athletes.

OBJECTIVES: The purpose of the present study was to examine knee extensor and flexor muscle strength ratios of an elite group of diving athletes. METHODS: Sixteen divers (10 females and 6 males) from the Brazil national team were assessed for lower-body strength. They had participated in international competitions such as the 2016 Olympic Games and 2015 Pan American Games. The dynamic concentric torque of their knee flexor and extensor muscles were evaluated using a Biodex isokinetic dynamometer. Bilateral tests were performed at 60º s-1. Flexor to extensor (F/E) peak torque ratio and percentage bilateral difference (BD%) was also measured. RESULTS: The results revealed that elite diving athletes produced higher than usual reported in previous studies for relative knee extension torque (3.2 for females and 3.6 for males N∙m∙kg-1). However, they presented low levels of knee flexor torque (1.5 for females and 1.8 for males N∙m∙kg-1). These results are reflected in a low F/E ratio (0.39 to 0.49). Males presented a greater BD% in knee flexors when compared to females (12.4% vs 6.6%). CONCLUSION: Elite diving athletes demonstrated high knee extensor and low knee flexor strength. This partially explains their low F/E ratio, which might increase risk of knee injuries. Strength and conditioning programs should strive to correct knee strength imbalances in diving athletes where necessary.

EFFECTS OF PERIODIC AND CONTINUOUS RESISTANCE TRAINING ON MUSCLE STRENGTH IN DETRAINED WOMEN.

It has been reported that periodic resistance training (retraining after short-term detraining) could maintain muscle performance. However, the training volume used in previous studies differed between continuous and periodic training groups. This study compared strength gains following 20 sessions of continuous and periodic resistance training programs. 60 healthy, detrained women were randomly assigned into one of two groups: (1) continuous resistance training group or (2) retraining resistance group. The continuous resistance training group performed a non-interrupted resistance training program for 10 wk., while the retraining resistance group trained for 5 wk., detrained 2 wk., and resumed training for 5 wk. All participants performed three sets of 8-12 maximum repetitions of lower- and upper-body exercises two days per week, with at least 48 hr. between sessions. There was no significant difference on knee extensors and elbow flexors peak torque gain between the continuous resistance training group and the retraining resistance group. The results suggest that 2 wk. of detraining does not affect strength gains after a total of 10 wk. in detrained women.

Neuromuscular and blood lactate responses to squat power training with different rest intervals between sets.

Studies investigating the effect of rest interval length (RI) between sets on neuromuscular performance and metabolic response during power training are scarce. Therefore, the purpose of this study was to compare maximal power output, muscular activity and blood lactate concentration following 1, 2 or 3 minutes RI between sets during a squat power training protocol. Twelve resistance-trained men (22.7 ± 3.2 years; 1.79 ± 0.08 cm; 81.8 ± 11.3 kg) performed 6 sets of 6 repetitions of squat exercise at 60% of their 1 repetition maximum. Peak and average power were obtained for each repetition and set using a linear position transducer. Muscular activity and blood lactate were measured pre and post-exercise session. There was no significant difference between RI on peak power and average power. However, peak power decreased 5.6%, 1.9%, and 5.9% after 6 sets using 1, 2 and 3 minutes of RI, respectively. Average power also decreased 10.5% (1 min), 2.6% (2 min), and 4.3% (3 min) after 6 sets. Blood lactate increased similarly during the three training sessions (1-min: 5.5 mMol, 2-min: 4.3 mMol, and 3-min: 4.0 mMol) and no significant changes were observed in the muscle activity after multiple sets, independent of RI length (pooled ES for 1-min: 0.47, 2-min: 0.65, and 3-min: 1.39). From a practical point of view, the results suggest that 1 to 2 minute of RI between sets during squat exercise may be sufficient to recover power output in a designed power training protocol. However, if training duration is malleable, we recommend 2 min of RI for optimal recovery and power output maintenance during the subsequent exercise sets. Key pointsThis study demonstrates that 1 minute of RI between sets is sufficient to maintain maximal power output during multiple sets of a power-based exercise when it is composed of few repetitions and the sets are not performed until failure. Therefore, a short RI should be considered when designing training programs for the development of muscular power.Short RI may be more practical for strength coaches under time constraints (i.e. 1 minute of RI required only 7 minutes to complete an exercise session, while with 2 minutes take 12 minutes, and 17 minutes with 3 minutes of RI).Future research is needed to examine the longitudinal effects of interval rest in training programs designed for the development of muscular power.

Graduated compression sleeves: effects on metabolic removal and neuromuscular performance.

The aim of this study was to examine the effects of upper-body graduated compression sleeves (CS) on neuromuscular and metabolic responses during a power training. Fifteen resistance trained men (age: 23.07 ± 3.92 years; body mass: 76.13 ± 7.62 kg; height: 177 ± 6 cm) performed 2 separate power training protocols, either wearing CS or placebo sleeves (PS), in a counterbalanced fashion. Participants first performed a familiarization session and a bench press 1 repetition maximum (1RM) test. The training protocol consisted of 6 sets of 6 repetitions of bench press with a load of 50% 1RM. Statistical analysis compared mean power, peak power, blood lactate, muscle activation, isometric strength, and repetitions to failure. Mean and peak power significantly (p ≤ 0.05) decreased with increasing sets. However, there was no significant difference (p > 0.05) on mean and peak power between protocols. Blood lactate clearance was also not significantly different (p > 0.05) between CS and PS. Muscle activation was not different between PRE and POST (p > 0.05) for any of the muscles analyzed. Isometric strength decreased from PRE to POST (p ≤ 0.05) and was not different between CS and PS. Repetitions to failure were not different between protocols (p > 0.05). These results demonstrate no positive performance effects when wearing graduated CS during power exercise in young trained men.

Effects of short-term isokinetic training with reciprocal knee extensors agonist and antagonist muscle actions: a controlled and randomized trial.

BACKGROUND: Previous studies have shown that preloading an antagonist muscle may increase the acute agonist neuromuscular performance. In addition, studies have suggested that very short-term resistance exercise (RE) programs may also be useful to increase strength and muscular performance. OBJECTIVES: To evaluate the effects of three days of RE using a reciprocal action method on the muscular performance of healthy men and to compare these effects with those of a traditional RE group. METHOD: Thirty-three men (21.1 ± 2.3 years) were randomly assigned to one of three groups: 1) reciprocal (REC; knee flexion immediately followed by a knee extension exercise); 2) traditional (TRA; non-preload; a concentric knee extension exercise); and 3) control (CON; no exercise). The REC and TRA subjects performed four sets of 10 repetitions at 60º/s with one minute of rest. The pre- and post-RE tests included two sets of four maximal concentric repetitions at 60º/s and 180º/s. A 3x2 ANOVA with Tukey post-hoc was used to analyze the differences in peak torque (PT), rating of acceleration development (RAD) and time to peak torque (TIMEtorque). RESULTS: A significant PT increase was found for REC and TRA (p<0.05) at 60º/s and for REC at 180º/s (p<0.05). There was a decrease in the RAD for REC and TRA (p<0.05), and TIMEtorque showed a significant decrease for REC. The inter-group analysis revealed that REC is more effective than TRA for PT gains at both velocities (p<0.05). CONCLUSION: It is recommended that REC offers benefits for the clinical practice of professionals involved in neuromuscular rehabilitation.

Effects of short-term isokinetic training with reciprocal knee extensors agonist and antagonist muscle actions: A controlled and randomized trial / Effects of short-term isokinetic training with reciprocal knee extensors agonist and antagonist muscle actions: A controlled and randomized trial

BACKGROUND: Previous studies have shown that preloading an antagonist muscle may increase the acute agonist neuromuscular performance. In addition, studies have suggested that very short-term resistance exercise (RE) programs may also be useful to increase strength and muscular performance. OBJECTIVES: To evaluate the effects of three days of RE using a reciprocal action method on the muscular performance of healthy men and to compare these effects with those of a traditional RE group. METHOD: Thirty-three men (21.1 ± 2.3 years) were randomly assigned to one of three groups: 1) reciprocal (REC; knee flexion immediately followed by a knee extension exercise); 2) traditional (TRA; non-preload; a concentric knee extension exercise); and 3) control (CON; no exercise). The REC and TRA subjects performed four sets of 10 repetitions at 60º/s with one minute of rest. The pre- and post-RE tests included two sets of four maximal concentric repetitions at 60º/s and 180º/s. A 3x2 ANOVA with Tukey post-hoc was used to analyze the differences in peak torque (PT), rating of acceleration development (RAD) and time to peak torque (TIMEtorque). RESULTS: A significant PT increase was found for REC and TRA (p<0.05) at 60º/s and for REC at 180º/s (p<0.05). There was a decrease in the RAD for REC and TRA (p<0.05), and TIMEtorque showed a significant decrease for REC. The inter-group analysis revealed that REC is more effective than TRA for PT gains at both velocities (p<0.05). CONCLUSION: It is recommended that REC offers benefits for the clinical practice of professionals involved in neuromuscular rehabilitation. .

CONTEXTUALIZAÇÃO: Estudos demonstraram que a pré-ativação de músculos antagonistas pode aumentar o desempenho neuromuscular agonista. Além disso, estudos sugerem que programas de exercício resistido (ER) de curta duração podem ser úteis para aumentar a força muscular e o desempenho. OBJETIVOS: Avaliar os efeitos de três sessões de ER por meio do método de ações recíprocas no desempenho muscular de homens sadios e comparar com um grupo de ER tradicional. MÉTODO: Trinta e três homens (21,1 ± 2,3 anos) foram randomicamente alocados em três grupos: Recíproco (REC: uma repetição de flexão do joelho imediatamente seguida por uma de extensão do joelho); Tradicional (TRA: exercício concêntrico de extensão do joelho) e Controle (CON: não realizaram exercício). O REC e o TRA realizaram quatro séries de dez repetições a 60º.s-1 com um minuto entre séries. As avaliações pré e pós-ER foram caracterizadas por duas séries de quatro repetições máximas a 60º.s-1 e 180º.s-1. Utilizou-se ANOVA 3x2, com post-hoc de Tukey para verificar diferenças no pico de torque (PT), taxa de desenvolvimento de aceleração (TDA) e tempo para atingir o PT (TEMPtorque). RESULTADOS: Houve um aumento do PT para o REC e o TRA (p<0.05) a 60º.s-1 e apenas para o REC a 180º.s-1 (p<0,05). Houve diminuição da TDA para o REC e o TRA (p<0,05) e, apenas no REC, o TEMPtorque apresentou quedas significantes. A análise intergrupos mostrou que o REC foi mais efetivo que o TRA para os ganhos de PT em ambas as velocidades (p<0,05). CONCLUSÃO: Sugere-se que a modalidade recíproca seja vantajosa para ...

Effect of adding single-joint exercises to a multi-joint exercise resistance-training program on strength and hypertrophy in untrained subjects.

The aim of this study was to examine the effect of adding single-joint (SJ) exercises to a multi-joint (MJ) exercise resistance-training program on upper body muscle size and strength. Twenty-nine untrained young men participated in a 10-week training session. They were randomly divided in 2 groups: the MJ group performed only MJ exercises (lat pulldown and bench press); the MJ+SJ group performed the same MJ exercises plus SJ exercises (lat pulldown, bench press, elbow flexion, and elbow extension). Before and after the training period, the muscle thickness (MT) of the elbow flexors was measured with ultrasound, and peak torque (PT) was measured with an isokinetic dynamometer. There was a significant (p < 0.05) increase in MT (6.5% for MJ and 7.04% for MJ+SJ) and PT (10.40% for MJ and 12.85% for MJ+SJ) in both groups, but there were no between-group differences. Therefore, this study showed that the inclusion of SJ exercises in a MJ exercise training program resulted in no additional benefits in terms of muscle size or strength gains in untrained young men.

Relationship between ventilatory threshold and muscle fiber conduction velocity responses in trained cyclists.

The relationship between surface electromyography (SEMG) amplitude and the ventilatory threshold has been extensively studied. However, previous studies of muscle fiber conduction velocity (MFCV) are scarce and present insufficient evidence concerning the relationship between MFCV and metabolic responses during cycling. Based on that fact, the purpose of this study is twofold: (1) to investigate the existence of a MFCV threshold (MFCVT) during cycling and (2) to verify if this possible breakpoint is correlated with the ventilatory threshold (VT) and the SEMG threshold (SEMGT). Eight trained male cyclists (age 36.0±9.7years) performed an incremental cycling test with initial workload of 150W gradually incremented by 20Wmin(-1) until the exhaustion. Gas analyses were conducted using a breath-by-breath open-circuit spirometry and SEMG were registered from vastus lateralis in each pedaling cycle with a linear array of electrodes. A bi-segmental linear regression computer algorithm was used to estimate VT, MFCVT and SEMGT respectively in the carbon dioxide production (VCO2), MFCV and electromyography root mean square (EMG RMS) curves. The one way ANOVA for repeated measures did not reveal any significant difference among VT (77.1±7.5% of VO2max), MFCVT (80.3±10.4% of VO2max) and SEMGT (81.9±11.7% of VO2max). The Bland and Altman procedure confirmed a good concordance between SEMGT and VT (Bias=5.5 of %VO2max) as well as MFCVT and VT (Bias=5.2 of %VO2max). The present findings suggest that muscle fiber conduction velocity threshold is a valid and reliable non-invasive tool to obtain information about ventilatory threshold in trained cyclists.

Treinamento isocinético de curto prazo promove aumento da força muscular em indivíduos jovens / Short-term isokinetic training increases muscle strength in young subjects

O objetivo foi avaliar os efeitos de treinamento isocinético de curta duração no desempenho muscular em indivíduos jovens. Onze homens sadios participaram de um programa de treinamento isocinético de curta duração, composto por 3 sessões (4 séries; 10 repetições isocinéticas concêntricas a 120°.s-1; 2 minutos de intervalo entre séries). A reprodutibilidade dos dados de 2 sessões foi avaliada pelo coeficiente de correlação intraclasses (CCI) e teste de Bland e Altman. As avaliações do treinamento foram aplicadas pré e pós a 2ª e 3ª sessões (1 série; 3 repetições concêntricas de extensão do joelho a 60°.s-1, 120°.s-1 e 180°.s-1). Utilizou-se a ANOVA para medidas repetidas e post-hoc de Tukey para verificar diferenças nos testes. O CCI variou de 0,97 a 0,98 em todas as velocidades. Ocorreu um aumento no pico de torque a 60°.s-1 (P=0,03) e 120°.s-1 (P=0,01) após 2 sessões de treinamento. Sugere-se que duas sessões de exercício isocinético foram suficientes para induzir ganhos de força na velocidade treinada (120°.s-1) e em velocidade de contração mais lenta (60°.s-1), em indivíduos jovens.

The aim was to investigate the effects of short-term isokinetic training on muscle performance in young individuals. Eleven healthy males subjects underwent to short-term training, consisting of 3 sessions (4 sets, 10 repetitions of concentric isokinetic exercise at 120°.s-1; 2-minute interval between sets). Data reproducibility from two sessions was evaluated by intraclass correlation coefficient (ICC) and Bland and Altman test. Training assessments were made pre and post the 2nd and 3rd sessions (1 set, 3 repetitions of concentric knee extension at 60°.s-1, 120°.s-1 and 180°.s-1). An ANOVA for repeated measures and Tukey post-hoc test was applied to determine differences between tests. The ICC ranged from 0.97 to 0.98 for all velocities. There was an increase in peak torque at 60°.s-1 (P=0,03) and 120°.s-1 (P=0,01) after 2 training sessions. Two sessions of isokinetic exercise were sufficient to induce strength increases at the training velocity (120°.s-1) and the slower contraction velocity (60°.s-1) in young individuals.