Using the Load-Velocity Profile for Predicting the 1RM of the Hexagonal Barbell Deadlift Exercise.

ABSTRACT: Lopes dos Santos, M, Mann, JB, Berton, R, Alvar, B, Lockie, RG, and Dawes, JJ. Using the load-velocity profile for predicting the 1RM of the hexagonal barbell deadlift exercise. J Strength Cond Res 37(1): 220-223, 2023-The aim of this study was to determine whether bar velocity can be used to estimate the 1 repetition maximum (1RM) on the hexagonal bar deadlift (HBD). Twenty-two National Collegiate Athletic Association Division I male ice hockey players (age = 21.0 ± 1.5 years, height = 182.9 ± 7.3 cm, and body mass = 86.2 ± 7.3 kg) completed a progressive loading test using the HBD at maximum intended velocity to determine their 1RM. The mean concentric velocity was measured for each load through a linear position transducer. The a priori alpha level of significance was set at p = 0.05. The mean concentric velocity showed a very strong relationship to %1RM (R2 = 0.85). A nonsignificant difference and a trivial effect size (ES) were observed between the actual and predicted 1RM (p = 0.90, ES = -0.08). Near-perfect correlations were also discovered between the actual and predicted 1RM (R = 0.93) with low typical error and coefficient of variation (5.11 kg and 2.53%, respectively). This study presented results that add the HBD to the list of exercises with established load-velocity relationships. The predictive ability for 1RM HBD indicates that this is a viable means of prediction of 1RM.

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.

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.

The effect of load based on body mass percentage on peak power output in the hang power clean, hang high pull, and mid-thigh clean pull.

BACKGROUND: Prescribing load at the peak power output (PPO) is one of the strategies utilized to enhance lower-body muscle power. PPO of an exercise is determined based on a relative percentage of the one-repetition maximum test (1RM). However, 1RM tests may be impractical in some weightlifting derivatives. This study aimed to identify the PPO of the hang power clean (HPC), hang high pull (HHP), and mid-thigh clean pull (MTCP) based on a relative percentage of body mass (BM). METHODS: Fifteen males with weightlifting experience performed HPC, HHP, and MTCP at loads ranging from 30-90% BM. Kinematic data were collected through a 16-camera infrared motion capture system and processed based on a three-dimensional lower-extremity model. Ground reaction force (GRF) data were collected from two force plates. PPO was calculated as the product of model center of mass velocity and combined vertical GRF during the concentric phase. RESULTS: PPO occurred at 90% BM for the HPC. In addition, the PPO occurred at 90% BM for the HHP and it was not different than 70% and 80% BM. At last, the PPO for MTCP occurred at 80% BM and it was not different than 60% and 70% BM. CONCLUSIONS: Relative percentages of BM can be used to determine PPO in the HPC, HHP, and MTCP. PPO during HPC is achieved at 90% BM, while the PPO for HHP and MTCP is achieved between 70% to 90% BM and 60 to 80% BM, respectively.

The effects of lifting straps in maximum strength, number of repetitions and muscle activation during lat pull-down.

The objective of the study was to investigate the effects of using lifting straps on the lat pull-down exercise on maximal strength, number of repetitions, and muscle activation. Twelve resistance-trained men participated (age 27 ± 4 years, body mass 84 ± 10 kg, height 177 ± 6 cm, resistance training experience 6.6 ± 2.4 years). All participants performed the 1RM tests and training protocols either with the lifting straps (WS) or without (WOS). Exercise sessions for both conditions (WS and WOS) consisted of 3 sets to concentric failure with a load of 70% of one repetition maximum (1RM) and rest intervals of 60 s. For the 1RM test, no difference was observed between WS and WOS conditions (96.5 ± 12.7 kg and 96.6 ± 11.9 kg, respectively). There were no differences between the WS and WOS conditions in the number of repetitions per set, total repetitions and latissimus dorsi muscle activation. In conclusion, the findings of this study demonstrate that the use of lifting straps in the lat pull-down exercise by resistance-trained individuals does not promote beneficial effect in the 1RM value, the number of repetitions performed with 70% of 1RM, and muscle activation.

Familiarization With Airflow-Restriction Mask During Resistance Exercise: Effect on Tolerance and Total Volume.

Teodoro, CL, Gáspari, AF, Berton, R, Barbieri, JF, Silva, M, Castaño, LAA, Guimarães, P, and Moraes, AC. Familiarization with airflow-restriction mask during resistance exercise: Effect on tolerance and total volume. J Strength Cond Res 33(7): 1762-1765, 2019-This study investigated whether familiarization with the airflow-restriction mask (AIRfr) increases tolerance and avoids negative effects on performance of resistance exercise (RE). Ten resistance-trained male subjects performed a familiarization session (FAM), followed by 2 testing sessions, with the AIRfr and without airflow restriction (SHAM) in a counterbalanced and randomized cross-over design. The FAM was performed with the same number of sets, load, and level of airflow-restriction as the AIRfr experimental session. Each session consisted of 4 sets of the leg press exercise with 70% 1 repetition maximum until voluntary failure and a 90-second rest interval between sets. During the FAM, 4 of the 10 subjects expressed some intolerance to the use of airflow restriction. Total volume was lower in the FAM than in the AIRfr (p = 0.01) and the SHAM (p = 0.02), whereas no differences were observed between the AIRfr and the SHAM (p = 0.90). The first use of the AIRfr may not be well tolerated by all subjects. However, a familiarization session with the AIRfr avoids negative interferences in the total volume during RE.

Effects of weightlifting exercise, traditional resistance and plyometric training on countermovement jump performance: a meta-analysis.

Jump performance is considered an important factor in many sports. Thus, strategies such as weightlifting (WL) exercises, traditional resistance training (TRT) and plyometric training (PT) are effective at improving jump performance. However, it is not entirely clear which of these strategies can enable greater improvements on jump height. Thus, the purpose of the meta-analysis was to compare the improvements on countermovement jump (CMJ) performance between training methods which focus on WL exercises, TRT, and PT. Seven studies were included, of which one study performed both comparison. Therefore, four studies comparing WL exercises vs. TRT (total n = 78) and four studies comparing WL exercises vs. PT (total n = 76). The results showed greater improvements on CMJ performance for WL exercises compared to TRT (ESdiff: 0.72 ± 0.23; 95%CI: 0.26, 1.19; P = 0.002; Δ % = 7.5 and 2.1, respectively). The comparison between WL exercises vs. PT revealed no significant difference between protocols (ESdiff: 0.15 ± 0.23; 95%CI: -0.30, 0.60; P = 0.518; Δ % = 8.8 and 8.1, respectively). In conclusion, WL exercises are superior to promote positive changes on CMJ performance compared to TRT; however, WL exercises and PT are equally effective at improving CMJ performance.

Magnitude of Muscle Strength and Mass Adaptations Between High-Load Resistance Training Versus Low-Load Resistance Training Associated with Blood-Flow Restriction: A Systematic Review and Meta-Analysis.

BACKGROUND: Low-load resistance training (< 50% of one-repetition maximum [1RM]) associated with blood-flow restriction (BFR-RT) has been thought to promote increases in muscle strength and mass. However, it remains unclear if the magnitude of these adaptations is similar to conventional high-load resistance training (> 65% 1RM; HL-RT). OBJECTIVE: To compare the effects of HL- versus BFR-RT on muscle adaptations using a systematic review and meta-analysis procedure. METHODS: Studies were identified via electronic databases based on the following inclusion criteria: (a) pre- and post-training assessment of muscular strength; (b) pre- and post-training assessment of muscle hypertrophy; (c) comparison of HL-RT vs. BFR-RT; (d) score ≥ 4 on PEDro scale; (e) means and standard deviations (or standard errors) are reported from absolute values or allow estimation from graphs. If this last criterion was not met, data were directly requested from the authors. RESULTS: The main results showed higher increases in muscle strength for HL- as compared with BFR-RT, even when considering test specificity, absolute occlusion pressure, cuff width, and occlusion pressure prescription. Regarding the hypertrophic response, results revealed similar effects between HL- and BFR-RT, regardless of the absolute occlusion pressure, cuff width, and occlusion pressure prescription. CONCLUSIONS: Based on the present data, maximum muscle strength may be optimized by specific training methods (i.e., HL-RT) while both HL- and BFR-RT seem equally effective in increasing muscle mass. Importantly, BFR-RT is a valid and effective approach for increasing muscle strength in a wide spectrum of ages and physical capacity, although it may seem particularly of interest for those individuals with physical limitations to engage in HL-RT.

Early metabolic response after resistance exercise with blood flow restriction in well-trained men: a metabolomics approach.

The present study aimed to compare the early metabolic response between high-load resistance exercise (HL-RE) and low-load resistance exercise with blood flow restriction (LL-BFR). Nine young, well-trained men participated in a randomized crossover design in which each subject completed LL-BFR, HL-RE, or condition control (no exercise) with a 1-week interval between them. Blood samples were taken immediately before and 5 min after the exercise sessions. Nuclear magnetic resonance spectroscopy identified and quantified 48 metabolites, 6 of which presented significant changes among the exercise protocols. The HL-RE promoted a higher increase in pyruvate, lactate, and alanine compared with the LL-BFR and the control. HL-RE and LL-BFR promoted a higher increase in succinate compared with the control; however, there was no difference between HL-RE and LL-BFR. Also, while there was no difference in acetoacetate between HL-RE and LL-BFR, a greater decrease was observed in both compared with the control. Finally, LL-BFR promoted a greater decrease in choline compared with the control. In conclusion, this study provides by metabolomics a new insight in metabolic response between LL-BFR and HL-RE by demonstrating a distinct response to some metabolites that are not commonly analyzed.

Effect of the flexibility training performed immediately before resistance training on muscle hypertrophy, maximum strength and flexibility.

PURPOSE: It has been suggested that flexibility training may reduce the total volume of training during resistance trainings. The purpose of this study was to compare the effect of flexibility training immediately before resistance training (FLEX-RT) versus resistance training without flexibility training (RT) on maximum strength and the vastus lateralis muscle cross-sectional area (CSA). METHODS: Participants had each leg assigned to RT or FLEX-RT. Both groups performed four sets of leg extensions to voluntary failure of 80% of one repetition maximum (1RM); however, FLEX-RT performed two sets of 25 s of static stretching before resistance training. Number of repetitions and total volume were calculated during weeks 1-5 and 6-10. Vastus lateralis muscle CSA, 1RM, and flexibility were assessed at baseline and after 10 weeks. RESULTS: The number of repetitions and total training volume were greater for RT than FLEX-RT for weeks 1-5 and 6-10. Regarding the vastus lateralis muscle CSA, a main time effect was observed, however, greater change was observed for RT than FLEX-RT (12.7 and 7.4%, respectively). A main time effect for 1RM was also observed with similar changes for RT and FLEX-RT (12.7 and 12.9%, respectively). Flexibility was increased pre- to post-training for FLEX-RT with greater change for FLEX-RT (10.1%) than RT (2.1%). CONCLUSION: These results show that performing flexibility training immediately before resistance training can contribute to a lower number of repetitions, total volume, and muscle hypertrophy.

Metabolic time-course response after resistance exercise: A metabolomics approach.

This study analysed the time course of the global metabolic acute response after resistance exercise (RE), with the use of proton nuclear magnetic resonance (1H NMR) spectroscopy. Ten young healthy males performed 4 sets of 10 repetitions at 70% of one-repetition maximum in the leg press and knee extension exercises and had the serum metabolome assessed at 5, 15, 30 and 60 min post-RE. Measurements were also performed 1 h earlier and immediately before the exercises, as an attempt to characterise each participant's serum metabolome at rest. One-way ANOVA was applied and the significance level was set at P ≤ 0.05. RE promoted an increase in 2-hydroxybutyrate, 2-oxoisocaproate, 3-hydroxyisobutyrate, alanine, hypoxanthine, lactate, pyruvate and succinate concentrations. However, isoleucine, leucine, lysine, ornithine and valine had their concentrations decreased post-RE compared with at rest. This is the first study to show significant changes in serum concentration of metabolites such as 2-oxoisocaproate, 2-hydroxybutyrate, 3-hydroxyisobutyrate, lysine, hypoxanthine and pyruvate post-RE, attesting metabolomics as an interesting approach to advance in the understanding of global RE-induced metabolic changes. Moreover, the present data could influence the time point of blood collection in the future studies that aims to investigate metabolism and exercise.

Influência da força muscular no volume e na intensidade da atividade física diária de idosos / Influence of muscle strength in the volume and intensity of daily physical activity in elderly

Resumo Diminuições no volume da atividade física diária (VAF - número de passos) e na intensidade da atividade física diária (IAF – velocidade média de caminhada) estão relacionadas com a maior incidência de quedas e aumento da incidência de doenças crônico-degenerativas em idosos. Portanto, identificar fatores que possam aumentar o VAF e a IAF torna-se essencial, principalmente para essa população. Desta forma, o objetivo do presente estudo foi investigar a influência da força muscular no VAF e na IAF de idosos saudáveis. Foram recrutados 18 participantes (10 homens e oito mulheres), com idade acima de 60 anos. Os participantes realizaram o teste de uma repetição máxima (1-RM) e utilizaram acelerômetro triaxial durante sete dias consecutivos, para mensurar o VAF e a IAF. Para analisar a influência da força no VAF e IAF realizou-se uma análise de regressão linear simples. Não foram observadas correlações significantes entre a força muscular e o VAF (p = 0,93; r2 = −0,06), assim como, entre a força muscular e a IAF (p = 0,08; r2 = 0,17). Conclui-se que a força muscular não influencia o VAF e a IAF de idosos saudáveis.(AU)

Abstract Reduction in the volume daily physical activity (VAF – number of steps) and in the intensity of daily physical activity (IAF- average walk velocity) are related with higher incidence of falls and increase of incidence of chronic diseases in elderly. However, the identification of factors which may increase the VAF and the IAF became essential, especially in this population. Therefore, the aim of the present study was to investigate the influence of muscle strength in VAF and the IAF of older healthy elderly. It were recruited 18 participants, ten men and eight women, aged above 60 years old. The participants performed the one repetition maximal test (1-RM) and afterwards they used the triaxial accelerometer, during seven consecutive days, to measure the VAF and the IAF. To analyze the influence of muscle strength in the VAF and IAF a simple linear regression analysis was performed. It was not observed significant correlations between the muscle strength and the VAF (p = 0.93; r2 = −0.06), or between muscle strength and the IAF (p = 0.08; r2 = 0.17). In conclusion the muscle strength does not influence the VAF and IAF of healthy older adults.(AU)

Time Course of Resistance Training-Induced Muscle Hypertrophy in the Elderly.

Extended periods of resistance training (RT) induce muscle hypertrophy. Nevertheless, to date, no study has investigated the time window necessary to observe significant changes in muscle cross-sectional area (CSA) in older adults. Therefore, this study investigated the time course of muscle hypertrophy after 10 weeks (20 sessions) of RT in the elderly. Fourteen healthy older subjects were randomly allocated in either the RT (n: 6) or control group (n: 8). The RT was composed of 4 sets × 10 repetitions (70-80% 1 repetition maximum [1RM]) in a leg press machine. The time course of vastus lateralis muscle hypertrophy (CSA) was assessed on a weekly basis by mode-B ultrasonography. Leg press muscle strength was assessed by dynamic 1RM test. Our results demonstrated that the RT group increased leg press 1RM by 42% (p ≤ 0.05) after 10 weeks of training. Significant increases in vastus lateralis muscle CSA were observed only after 18 sessions of training (9 weeks; p ≤ 0.05; 7.1%). In conclusion, our training protocol promoted muscle mass accrual in older subjects, and this was only observable after 18 sessions of RT (9 weeks).

Comparisons between low-intensity resistance training with blood flow restriction and high-intensity resistance training on quadriceps muscle mass and strength in elderly.

High-intensity resistance training (HRT) has been recommended to offset age-related loss in muscle strength and mass. However, part of the elderly population is often unable to exercise at high intensities. Alternatively, low-intensity resistance training with blood flow restriction (LRT-BFR) has emerged. The purpose of this study was to compare the effects of LRT-BFR and HRT on quadriceps muscle strength and mass in elderly. Twenty-three elderly individuals, 14 men and 9 women (age, 64.04 ± 3.81 years; weight, 72.55 ± 16.52 kg; height, 163 ± 11 cm), undertook 12 weeks of training. Subjects were ranked according to their pretraining quadriceps cross-sectional area (CSA) values and then randomly allocated into one of the following groups: (a) control group, (b) HRT: 4 × 10 repetitions, 70-80% one repetition maximum (1RM), and (c) LRT-BFR: 4 sets (1 × 30 and 3 × 15 repetitions), 20-30% 1RM. The occlusion pressure was set at 50% of maximum tibial arterial pressure and sustained during the whole training session. Leg press 1RM and quadriceps CSA were evaluated at before and after training. A mixed-model analysis was performed, and the significance level was set at p ≤ 0.05. Both training regimes were effective in increasing pre- to post-training leg press 1RM (HRT: ∼54%, p < 0.001; LRT-BFR: ∼17%, p = 0.067) and quadriceps CSA (HRT: 7.9%, p < 0.001; LRT-BFR: 6.6%, p < 0.001); however, HRT seems to induce greater strength gains. In summary, LRT-BFR constitutes an important surrogate approach to HRT as an effective training method to induce gains in muscle strength and mass in elderly.

Dor muscular e atividade de creatina quinase após ações excêntricas: uma análise de cluster / Muscle soreness and creatine kinase activity after eccentric actions: a cluster analysis / Dolor muscular y actividad de creatina kinasa tras acciones excéntricas: un análisis de cluster

INTRODUÇÃO: O exercício excêntrico máximo promove queda da capacidade de geração de força, aumento de dor muscular de início tardio (DMIT) e extravasamento de creatina quinase (CK) no sangue. No entanto, essas respostas ao exercício excêntrico demonstram alta variabilidade interindivíduos. OBJETIVOS: Classificar e analisar essas respostas segundo a vulnerabilidade individual, por meio da magnitude da redução dos níveis de força após exercício excêntrico. MÉTODOS: Dezoito sujeitos (11 homens e sete mulheres com idade entre 18 e 71 anos) saudáveis realizaram cinco séries de seis ações excêntricas máximas para flexores do cotovelo em dinamômetro isocinético (90°s- 1, amplitude de movimento de 80 a 20°). Foram analisadas contração voluntária muscular concêntrica máxima (CVM), DMIT e CK pré, pós (exceto CK), 24 h, 48 h, 72 h e 96 h após o protocolo. Os indivíduos foram classificados como "baixos" (BR) e "altos" respondedores (AR) ao pico de queda de CVM pós-exercício seguindo-se uma análise de cluster e comparação entre grupos para CVM, DMIT e CK com teste-t independente. RESULTADOS: A comparação entre BR e AR indicou maiores valores de queda de CVM para o grupo AR (AR: -30,7 ± 3,3%; BR: -14,1 ± 2,2%, p < 0,001) e maior DMIT também para o grupo AR (AR: 33,0 ± 8,6 mm; BR: 10,2 ± 2,5 mm, p = 0,033); no entanto, os valores de pico de atividade de CK não diferiram entre os grupos (AR: 232,1 ± 54,8 UI.L- 1; BR: 306,1 ± 82,3 UI.L- 1, p = 0,490). CONCLUSÃO: A classificação dos indivíduos em grupos de baixos e altos respondedores foi importante para demonstrar que o grupo mais responsivo à queda de força após exercício excêntrico ...

INTRODUCTION: Maximal eccentric exercise promotes decreases in muscular strength, increases in delayed-onset muscle soreness (DMIT) and leakage of creatine kinase (CK) in the blood. However, these responses to eccentric exercise demonstrated large inter-individual variability. OBJECTIVES: To classify and analyze these responses according to individual vulnerability through the magnitude of the reduction of strength following eccentric exercise. METHODS: Eighteen healthy subjects (11 men and seven women aged 18 to 71 years) performed five sets of six maximal isokinetic eccentric actions of the elbow flexors using an isokinetic dynamometer (90°s- 1, range of motion 80-20°). Maximum voluntary concentric muscle contraction (CVM), DMIT and CK pre-, post (except CK), 24h, 48h, 72h and 96h were analyzed after the protocol. Individuals were classified as "low" (BR) and "high" (AR) responders at the peak of CVM decrease post-exercise using a k-means cluster analysis and compared between groups for CVM, DMIT and CK with independent t-test. RESULTS: The comparison between BR and AR showed higher CVM decrease for AR (AR: -30.7±3.3%, BR: -14.1±2.2%, p<0.001) and higher DMIT also for AR group (AR: 33.0±8.6 mm; BR: 10.2±2.5 mm, p=0.033) however, the peak values of CK activity did not differ between groups (AR: 232.1±54.8 UI.L- 1, BR: 306.1±82.3 UI.L- 1, p=0.490). CONCLUSION: The classification of the subjects into low and high responders groups was important to demonstrate that the most responsive group to strength decrease after eccentric exercise also shows higher DMIT levels; notwithstanding, for creatine kinase this relation could not be established. .

INTRODUCCIÓN: El ejercicio excéntrico máximo promueve reducciones de capacidad de generación de energía, aumento de dolor muscular de aparición tardía (DMIT), y escape de creatina kinasa (CK) en la sangre. Sin embargo, estas respuestas al ejercicio excéntrico demostraron una gran variabilidad interindividual. OBJETIVOS: Clasificar y analizar las respuestas de acuerdo a la vulnerabilidad individual al grado de disminución de la fuerza después del ejercicio excéntrico. MÉTODOS: Dieciocho sujetos sanos (11 hombres y siete mujeres de entre 18 a 71 años) han realizado cinco series de seis acciones excéntricas isocinéticas máximas de los flexores del codo utilizando un dinamómetro isocinético (90º s- 1, rango de movimiento 80-20°). La contracción concéntrica muscular voluntaria máxima (CVM), DMIT y CK pre-, inmediatamente después (excepto CK), 24h, 48h, 72h y 96h fue analizada después del protocolo. Los individuos fueron clasificados en "bajos" (BR) y "altos" (AR) respondedores, conforme el pico de declinación en la CVM después del ejercicio mediante un análisis de cluster y comparados entre los grupos para la CVM, DMIT y CK con pruebas t-independientes. RESULTADOS: La comparación entre BR y AR indicó mayor disminución de la CVM para AR (AR: -30,7 ± 3,3%, BR: -14,1 ± 2,2%, p < 0,001) y mayor DMIT también para AR (AR: 33,0 ± 8,6 mm; BR : 10,2 ± 2,5 mm, p = 0,033), sin embargo, los valores de pico de actividad de la CK no difirieron entre los grupos (AR: 232,1 ± 54,8 UI.L-1, BR: 306,1 ± 82,3 UI.L-1, p = 0,490). CONCLUSIÓN: La clasificación de los sujetos en los grupos bajos y altos respondedores fue importante para demostrar que el grupo más sensible a la disminución de la fuerza después del ejercicio excéntrico ...

Sixteen weeks of resistance training can decrease the risk of metabolic syndrome in healthy postmenopausal women.

BACKGROUND: The postmenopausal phase has been considered an aggravating factor for developing metabolic syndrome. Notwithstanding, no studies have as yet investigated the effects of resistance training on metabolic syndrome in postmenopausal women. Thus, the purpose of this study was to verify whether resistance training could reduce the risk of metabolic syndrome in postmenopausal women. METHODS: Twenty postmenopausal women were randomly assigned to a resistance training protocol (n = 10, 53.40 ± 3.95 years, 64.58 ± 9.22 kg) or a control group (n = 10, 53.0 ± 5.7 years, 64.03 ± 5.03 kg). In the resistance training protocol, ten exercises were performed, with 3 × 8-10 maximal repetitions three times per week, and the load was increased every week. Two-way analysis of variance was used to evaluate specific metabolic syndrome Z-score, high density lipoprotein cholesterol, fasting blood glucose, triglycerides, waist circumference, blood pressure, strength, and body composition. The level of statistical significance was set at P < 0.05. RESULTS: The main results demonstrated a significant decrease of metabolic syndrome Z-score when the postmenopausal women performed resistance training (P = 0.0162). Moreover, we observed decreases in fasting blood glucose for the resistance training group (P = 0.001), and also significant improvements in lean body mass (P = 0.042, 2.46%), reduction of body fat percentage (P = 0.001, -6.75%) and noticeable increases in muscle strength after resistance training to leg press (P = 0.004, 41.29%) and bench press (P = 0.0001, 27.23%). CONCLUSION: It was concluded that resistance training performed three times a week may reduce the metabolic syndrome Z-score with concomitant decreases in fasting blood glucose, improvements in body composition, and muscle strength in postmenopausal women.

Comparison of maximal muscle strength of elbow flexors and knee extensors between younger and older men with the same level of daily activity.

BACKGROUND: Aging promotes neuromuscular loss, significantly reducing muscle strength. The magnitude of loss of strength seems to be different between the limbs, probably because of differences in activities of daily living (ADL). Therefore, the present study compared the muscle strength of the elbow flexors and knee extensors in younger (n = 7, mean age 23.3 ± 1.2 years) and older (n = 5, mean age 61.8 ± 2.6 years) men matched by ADL level. METHODS: The study participants performed maximal concentric, isometric, and eccentric contractions of the elbow flexors and knee extensors using an isokinetic dynamometer following a crossover study design. Changes in the dependent variables were compared using mixed model analysis (limb versus age). RESULTS: The main results demonstrated that concentric, eccentric, and mean contraction torques for knee extensors were significantly (P < 0.05) higher for younger men than for elderly men. On the other hand, no statistically significant difference (P > 0.05) was found in concentric, isometric, eccentric, and mean torques for elbow flexors between younger and older individuals. CONCLUSION: These results show that elbow flexors maintain better strength than knee extensors through aging, even when comparing individuals with similar ADL levels.

Dano muscular: resposta inflamatória sistêmica após ações excêntricas máximas / Muscle damage: systemic inflammatory response after maximal eccentric actions / Daño muscular: respuesta inflamatoria sistémica después de acciones excéntricas máximas

O objetivo deste estudo foi analisar a resposta inflamatória induzida por grande número de ações excêntricas (AE) máximas realizadas pelos flexores do cotovelo. Participaram do estudo nove homens jovens, que realizaram 35 séries de seis AE nos flexores de cotovelo, com intervalo de um minuto, utilizando um dinamômetro isocinético em uma velocidade de 210º.s-1. As variáveis mensuradas foram: a contração isométrica voluntaria máxima (CIVM), a amplitude de movimento (AM), a dor muscular de inicio tardio (DMIT), a interleucina-6 (IL-6) e o fator de necrose tumoral alfa (TNF-α). Alterações significantes foram observadas para os marcadores indiretos de dano muscular (CIVM, AM e DMIT), entretanto não houve modificações para os marcadores inflamatórios (IL-6 e TNF-α). Em conclusão, os resultados demonstraram que mesmo com alterações nos marcadores indiretos de dano muscular após a realização de um grande número de AE não foram observadas alterações na resposta inflamatória sistêmica.

The objective of this study was to analyze the magnitude of the inflammatory response induced by a high number of eccentric actions (AE) of the elbow flexors. Participated on this study nine young men who performed 35 sets of six AE of the elbow flexors, with an one minute interval, using an isokinetic dynamometer at 210º.s-1. Maximum voluntary isometric contraction (MVIC), range of motion (ROM), delayed onset muscle soreness (DOMS), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) were measured. Significant changes were observed for markers of muscle damage (MVIC, ROM and DOMS), however, there were no changes on inflammatory markers IL-6 and TNF-α. In conclusion, the results show that even with large numbers of AE and changes in indirect markers of muscle damage, no change was observed in the systemic inflammatory response.

El objetivo del presente estudio fue analizar la magnitud de la respuesta inflamatoria inducida por un gran número de acciones excéntricas (AE) de los flexores del codo. Han participado del estudio nueve jóvenes que llevaron a cabo 35 series de seis AE de los flexores del codo, con un intervalo de un minuto, utilizando un dinamómetro isocinético a 210º.s-1. Fueran mensurados la máxima contracción voluntaria isométrica (CIVM), la amplitud de movimiento (AM), el dolor muscular de aparición tardía (DMIT), la interleucina 6 (IL-6) y el factor de necrosis tumoral alfa (TNF-α). Se observaron cambios significativos para los marcadores de daño muscular (CIVM, AM y DMIT), sin embargo, no hubo cambios en los marcadores de inflamación IL-6 y TNF-α. En conclusión, los resultados indican que mismo con un gran número de AE y cambios en los marcadores indirectos de daño muscular, no se observaron cambios en la respuesta inflamatoria sistémica.

Efeito do treinamento concorrente sobre a força e hipertrofia muscular de mulheres na pós-menopausa / Effect of concurrent training on muscle hypertrophy and strength of postmenopausal women

A associação do treinamento de força (TF) e aeróbio (TA), conhecido com treinamento concorrente (TC), parece diminuir os ganhos de força e hipertrofia muscular quando comparado ao TF isolado. Dessa forma, esse estudo teve como objetivo comparar os efeitos de16 semanas de TF e TC sobre os indicadores de hipertrofia e a força muscular em mulheres de meia-idade na pós-menopausa. Participaram 24 mulheres, não ativas fisicamente, subdivididas em três grupos: Grupo TC (n=8), Grupo TF (n=8) e Grupo Controle (n=8). Os treinamentos foram compostos de duas etapas (E1 e E2) com duração de oito semanas cada, e frequência de três sessões/semana (TF: 10 exercícios com 3 x 8-10 RM; TC: 6 exercícios com 3 x 8-10 RM, seguido de 30 min de caminhada ou corrida a 55-85% VO2pico). Foram avaliadas a área muscular de coxa (AMC), força máxima e consumo pico de oxigênio (VO2pico). Os resultados demonstraram aumento na força máxima nos exercícios leg press, supino reto e rosca direta para o TF e TC, sem diferença entre eles. Com relação aos indicadores hipertróficos não houve aumento na AMC para o TF e TC. Houve aumento do VO2pico somente para o TC. Dessa forma, podemos concluir que o TC, realizado com as recomendações mínimas de TA preconizadas pelo American College of Sports Medicine (ACSM), não promoveu efeito de interferência na força máxima e hipertrofia muscular de mulheres de meia-idade na pós-menopausa.

The combination of strength (TF) and aerobic training (TA), known as concurrent training (TC), seems to diminish the muscle strength and hypertrophy gains when compared with isolated TF. This study aimed to compare the effects of 16 weeks of concurrent training (TC) and resistance training (TF) on hypertrophic indicators and muscle strength of middle-aged postmenopausal women. Participated 24 non-active women randomly assigned in three groups: TC (n=8), TP (n=8) and control group (GC, n=8). Both training protocols were divided in two phases lasting eight weeks with a three weeks sessions frequency (TF: 10 exercises, 3x8-10 RM; TC: 6 exercises, 3x8-10 RM followed by 30 min of walking or running at 55-85% VO2peak). It were assessed thigh muscle area (AMC), muscle strength and maximal oxygen uptake (VO2peak). Our data showed that both training protocols (i.e., TF and TC) significantly increased maximal strength in leg press, bench press and arm curl without differences between groups. Regarding the hypertrophic indicators there was no difference in AMC for both training groups. VO2peak significantly increased only for TC. Thus, our data showed that when TC is held closely to the minimum of American College of Sports Medicine (ACSM) recommendation for aerobic training, no interference effect is observed in muscle strength and hypertrophic indicators in middle-aged postmenopausal women.