This study investigated the association between isokinetic peak torque (PT) of quadriceps and the corresponding peak rate of force development (peak RFD) during the recovery of eccentric exercise. Twelve untrained men (aged 21·7 ± 2·3 year) performed 100 maximal eccentric contractions for knee extensors (10 sets of 10 repetitions with a 2-min rest between each set) on isokinetic dynamometer. PT and peak RFD accessed by maximal isokinetic knee concentric contractions at 60° s(-1) were obtained before (baseline) and at 24 and 48 h after eccentric exercise. Indirect markers of muscle damage included delayed onset of muscle soreness (DOMS) and plasma creatine kinase (CK) activity. The eccentric exercise resulted in elevated DOMS and CK compared with baseline values. At 24 h, PT (-15·3%, P = 0·002) and peak RFD (-13·1%, P = 0·03) decreased significantly. At 48 h, PT (-7·9%, P = 0·002) was still decreased but peak RFD have returned to baseline values. Positive correlation was found between PT and peak RFD at baseline (r = 0·62, P = 0·02), 24 h (r = 0·99, P = 0·0001) and 48 h (r = 0·68, P = 0·01) after eccentric exercise. The magnitude of changes (%) in PT and peak RFD from baseline to 24 h (r = 0·68, P = 0·01) and from 24 to 48 h (r = 0·68, P = 0·01) were significantly correlated. It can be concluded that the muscle damage induced by the eccentric exercise affects differently the time course of PT and peak RFD recovery during isokinetic concentric contraction at 60° s(-1). During the recovery from exercise-induced muscle damage, PT and peak RFD are determined but not fully defined by shared putative physiological mechanisms.
This study aimed to investigate the dependence of oxygen uptake (VO₂) kinetics on pedal cadence during moderate-intensity exercise following exercise-induced muscle damage (EIMD). Twenty untrained males were randomly assigned to a 50 revolution per minute (rpm) (age, 23.3 ± 1.8 years; VO₂(max), 38.9 ± 2.8 mL·kg⁻¹·min⁻¹) or 100 rpm group (age, 24.4 ± 3.5 years, VO₂(max), 42.9 ± 4.3 mL·kg⁻¹·min⁻¹). Participants completed "step" tests to moderate-intensity exercise from an unloaded baseline on a cycle ergometer before (baseline) and at 24 and 48 h after muscle-damaging exercise (10 sets of 10 eccentric contractions performed on an isokinetic dynamometer with a 2-min rest between each set). Pedal cadence was kept constant throughout each cycling trial (50 or 100 rpm). There were no changes in phase II pulmonary VO₂ kinetics following EIMD for the 50 rpm group (baseline = 35 ± 4 s; 24 h = 35 ± 7 s; and 48 h = 36 ± 9 s). However, the phase II VO₂ was significantly greater at 24 h (59 ± 27 s) compared with baseline (39 ± 6 s) and 48 h (40 ± 9 s) for the 100 rpm group. It is concluded that the effects of EIMD on phase II VO₂ kinetics during moderate-intensity cycling exercise is dependent on pedal cadence. The slower VO₂ kinetics after muscle damage suggests that type II fibers are involved during transition to moderate-intensity exercise at high pedal cadence.
Foi objetivo deste estudo caracterizar a relação entre o nível de aptidão física, desempenho e solicitação metabólica em futebolistas durante situação real de jogo. Seis jogadores de futebol profissional com média de idade de 20,8 ± 2,6 anos (17-25), peso 70,4 ± 7,5kg (63-81,3) e altura 173,3 ± 9,7cm (166-188), foram submetidos a testes de aptidão física em campo e análise cinematográfica durante a partida. Os testes de aptidão física foram realizados em campo, com medições de lactato sanguíneo. A via metabólica alática foi avaliada por meio de cinco corridas na distância de 30m, em velocidade máxima, com pausa passiva de um minuto entre cada corrida. As concentrações de lactato foram medidas no 1º, 3º e 5º minuto após o término das cinco corridas. Para detecção do limiar anaeróbio foram realizadas 3 corridas de 1.200m nas intensidades de 80, 85 e 90% da velocidade máxima para essa distância, com intervalo passivo de 15 minutos entre cada corrida. As dosagens de lactato sanguíneo foram feitas no 1º, 3º e 5º minuto de repouso passivo após cada corrida. Os futebolistas foram submetidos à filmagem individual durante o transcorrer do jogo e as concentrações de lactato foram medidas antes, no intervalo e no final da partida para análise da solicitação energética e metabólica, respectivamente. Os seguintes resultados foram verificados: 1) o limiar anaeróbio em velocidade de corrida, correspondente à concentração de lactato sanguíneo de 4mmol.L_1 foi encontrado aos 268 ± 28m.min_1 ou 16,1 ± 1,6km.h_1; 2) a velocidade média e a concentração de lactato máximo nas corridas de 30m foram de 6,9 ± 0,2m.s_1 e 4,5 ± 1,0mmol.L_1, respectivamente; 3) a distância total percorrida foi de 10.392 ± 849m, sendo 5.446 ± 550m para o primeiro e 4.945 ± 366m para o segundo tempo, respectivamente; 4) os valores médios encontrados nas concentrações de lactato sanguíneo foram de 1,58 ± 0,37; 4,5 ± 0,42 e 3,46 ± 1,54mmol.L_1 antes, no intervalo do primeiro para o segundo tempo e ao final da a,respectivamente; e 5) a distância média total atingida ao final das partidas pelos jogadores de meio-campo (10.910 ± 121m) foi ligeiramente maior que a percorrida pelos atacantes (10.377 ± 224m) e defensores (9.889 ± 102m), mas não significativa. Houve correlação negativa (r =- 0,84; p < 0,05) entre o limiar anaeróbio (268 ± 28m.min_1 ou 16,1 ± 1,6km.h_1) e a concentração de lactato sanguíneo (4,5 ± 0,4 mmol.L_1) no primeiro tempo do jogo. Portanto, os resultados sugerem que a capacidade aeróbia é um determinante importante para suportar a longa duração da partida e recuperar mais rapidamente os futebolistas dos esforços realizados em alta intensidade, com o desenvolvimento de concentrações de lactato sanguíneo menores ao final do primeiro e segundo tempo das partidas.
The objective of this study was to investigate the influence of active static stretching on the maximal isometric muscle strength (maximal voluntary contraction [MVC]) and rate of force development (RFD) determined within time intervals of 30, 50, 100, and 200 milliseconds relative to the onset of muscle contraction. Fifteen men (aged 21.3 ± 2.4 years) were submitted on different days to the following tests: (a) familiarization session to the isokinetic dynamometer; (b) 2 maximal isometric contractions for knee extensors in the isokinetic dynamometer to determine MVC and RFD (control); and (c) 2 active static stretching exercises for the dominant leg extensors (10 × 30 seconds for each exercise with a 20-second rest interval between bouts). After stretching, the isokinetic test was repeated (poststretching). Conditions 2 and 3 were performed in random order. The RFD was considered as the mean slope of the moment-time curve at time intervals of 0-30, 0-50, 0-100; 0-150; and 0200 milliseconds relative to the onset of muscle contraction. The MVC was reduced after stretching (285 ± 59 vs. 271 ± 56 N · m, p < 0.01). The RFD at intervals of 0-30, 0-50, and 0-100 milliseconds was unchanged after stretching (p > 0.05). However, the RFD measured at intervals of 0-150 and 0-200 milliseconds was significantly lower after stretching (p < 0.01). It can be concluded that explosive muscular actions of a very short duration (<100 milliseconds) seem less affected by active static stretching when compared with actions using maximal muscle strength.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.