Abstract
We recently developed a high intensity one leg dynamic exercise (OLDE) protocol to measure muscle endurance and investigate the central and peripheral mechanisms of muscle fatigue. The aims of the present study were to establish the reliability of this novel protocol and describe the isokinetic muscle fatigue induced by high intensity OLDE and its recovery. Eight subjects performed the OLDE protocol (time to exhaustion test of the right leg at 85% of peak power output) three times over a week period. Isokinetic maximal voluntary contraction torque at 60 (MVC60), 100 (MVC100) and 140 (MVC140) deg/s was measured pre-exercise, shortly after exhaustion (13 ± 4 s), 20 s (P20) and 40 s (P40) post-exercise. Electromyographic (EMG) signal was analyzed via the root mean square (RMS) for all three superficial knee extensors. Mean time to exhaustion was 5.96 ± 1.40 min, coefficient of variation was 8.42 ± 6.24%, typical error of measurement was 0.30 min and intraclass correlation was 0.795. MVC torque decreased shortly after exhaustion for all angular velocities (all P < 0.001). MVC60 and MVC100 recovered between P20 (P < 0.05) and exhaustion and then plateaued. MVC140 recovered only at P40 (P < 0.05). High intensity OLDE did not alter maximal EMG RMS of the three superficial knee extensors during MVC. The results of this study demonstrate that this novel high intensity OLDE protocol could be reliably used to measure muscle endurance, and that muscle fatigue induced by high intensity OLDE should be examined within ~ 30 s following exhaustion.
Highlights
Endurance performance is extensively studied in exercise physiology using cycling and/or running exercise (e.g. [1,2,3,4])
The aims of the present study were to assess the reliability of a novel high intensity one leg dynamic exercise (OLDE) protocol to measure muscle endurance, and to describe the isokinetic muscle fatigue induced by high intensity OLDE and its recovery
Froyd et al [32] demonstrated a significant recovery in skeletal muscle function within 1–2 minutes after completion of a one-leg isokinetic time trial performed at high intensity. These results demonstrate that to fully appreciate the extent of neuromuscular alterations induced by high intensity dynamic exercise, assessment of muscle fatigue must be performed within 30 s of cessation of the exercise
Summary
Endurance performance (i.e. exercise duration > 1 min) is extensively studied in exercise physiology using cycling and/or running exercise (e.g. [1,2,3,4]). Endurance performance (i.e. exercise duration > 1 min) is extensively studied in exercise physiology using cycling and/or running exercise Despite being close to real competition events by involving the whole-body, the use of cycling and/or running exercise presents some important limitations to understand the role of the central nervous system (CNS) in the regulation of muscle fatigue and endurance performance. As whole-body exercise involves greater systemic responses than isolated exercise [5], it is difficult to interpret some. One Leg Dynamic Exercise and Muscle Fatigue specific experimental manipulations aiming to understand CNS processes regulating muscle fatigue and endurance performance (e.g. manipulation of III-IV muscle afferents [6, 7]). Due to the aforementioned limitations, the development of a new exercise model is required to better investigate the CNS processes regulating endurance performance
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