Acute effects of short-duration isolated static stretching or combined with dynamic exercises on strength, jump and sprint performance

Summary Objective This study aimed to investigate the acute effects of a short-duration isolated static stretching or combined with dynamic plyometric exercises on the performance of some anaerobic parameters (strength, jumping and sprinting). Methods During three distinct sessions and after a standardized warm-up, 15 participants randomly performed static stretching exercises alone, static stretching combined with plyometric exercises and no stretch. Total stretch duration was 20 seconds long per muscle group (quadriceps, hamstrings and calf muscles). Tests included maximal quadriceps muscle strength, countermovement jumps and 15 m sprints. Results Whatever the condition, maximal strength …

Fatigue and Recovery After High-Intensity Exercise Part I: Neuromuscular Fatigue

The contribution of central and peripheral factors to muscle fatigue were quantified following a high-intensity uphill running exercise. Eight male volunteers performed an intermittent exercise at 120 % of maximal aerobic speed on a treadmill with an 18 % grade. Electrically evoked and voluntary contractions of the knee extensors and EMG of the two vastii were analyzed before and immediately after the high-intensity exercise. Isometric maximal voluntary contraction decreased slightly (-7+/-8 %; p < 0.05) after exercise but no changes were found in the level of maximal activation or in the torque produced by a 80 Hz maximal stimulation applied to the femoral nerve. Following exercise, the si…

Alteration of Neuromuscular Function After a Prolonged Road Cycling Race

The aim of this study was to characterize neuromuscular fatigue in knee extensor muscles after a prolonged cycling exercise. During the two days preceding a 140-km race (mean +/- SD duration: 278.2 +/- 24.9 min) and 15 to 30 min after, maximal percutaneous electrical stimulations were applied to the femoral nerve of 11 trained cyclists. Electrically evoked superimposed twitches and trains of 6 stimulations were delivered during isometric maximal voluntary contraction (MVC) to determine maximal voluntary activation (% VA). Knee extensors MVC decreased with fatigue from 158.2 +/- 29.6 to 144.2 +/- 30.0 Nm (p < 0.01), but no central activation failure was detected after the race. The average r…

Neuromuscular Differences Between Endurance-Trained, Power-Trained, and Sedentary Subjects

This study tested the hypothesis that neuromuscular characteristics of plantar flexor (PF) and knee extensor (KE) muscles explain differences of both performance in vertical jump and maximal voluntary isometric contraction (MVC) between endurance-trained (END, n = 9), power-trained (POW, n = 8), and sedentary subjects (SED, n = 8). Evoked twitch characteristics of PF and KE were measured. MVC, maximal voluntary activation (%VA) of KE, and performance in vertical jump were also measured. POW have higher maximal rate of twitch force development (MRFD) than SED and END for both PF (p < 0.05) and KE (p < 0.01); %VA and MVC were higher for POW and END than SED (p < 0.01). Higher performances wer…

Effect of two types of fatigue on the VO2 slow component

Fatigue and Recovery After High-Intensity Exercise Part II: Recovery Interventions

The purpose of this study was to determine the effect of three types of recovery intervention to neuromuscular function after high-intensity uphill running exercise. The 20-min recovery interventions were (i) passive, (ii) active (running at 50 % of maximal aerobic speed), and (iii) low-frequency electromyostimulation. Evoked twitch and maximal voluntary contractions of knee extensor muscles (KE) and EMG of the vastus lateralis and vastus medialis were analysed immediately after the exercise, 10 min after the end of the recovery periods, and 65 min after the exercise (Post65). An all-out running test was also performed 80 min after the end of the fatiguing exercise. No significant differenc…

Influence of ultra-long-term fatigue on the oxygen cost of two types of locomotion.

The aim of this study was to examine the effects of fatigue induced by a 65-km ultramarathon on the oxygen cost of running (Cr) and cycling (Ccycl). The day before and immediately after the race, a group of nine well-trained male subjects performed two sub-maximal 4-min exercise bouts: one cycling at a power corresponding to 1.5 W · kg−1 body mass on an electromagnetically braked ergometer, and one running at 11 km · h−1 on a flat asphalt roadway. Before oxygen cost determinations, the subjects performed 12 “ankle” jumps at a given frequency that was fixed by an electronic metronome (2.5 Hz). From the non-fatigued to the fatigued condition, there was a significant increase in minute ventila…

Alterations of neuromuscular function after an ultramarathon.

Neuromuscular fatigue of the knee extensor (KE) and plantar flexor (PF) muscles was characterized after a 65-km ultramarathon race in nine well-trained runners by stimulating the femoral and tibial nerves, respectively. One week before and immediately after the ultramarathon, maximal twitches were elicited from the relaxed KE and PF. Electrically evoked superimposed twitches of the KE were also elicited during maximal voluntary contractions (MVCs) to determine maximal voluntary activation. MVC and maximal voluntary activation decreased significantly after the ultramarathon (−30.2 ± 18.0% and −27.7 ± 13.0%, respectively; P &lt; 0.001). Surprisingly, peak twitch increased after the ultramara…

Mechanisms contributing to knee extensor strength loss after prolonged running exercise.

The aim of this study was to identify the mechanisms that contribute to the decline in knee extensor (KE) muscles strength after a prolonged running exercise. During the 2 days preceding a 30-km running race [duration 188.7 ± 27.0 (SD) min] and immediately after the race, maximal percutaneous electrical stimulations (single twitch, 0.5-s tetanus at 20 and 80 Hz) were applied to the femoral nerve of 12 trained runners. Superimposed twitches were also delivered during isometric maximal voluntary contraction (MVC) to determine the level of voluntary activation (%VA). The vastus lateralis electromyogram was recorded. KE MVC decreased from pre- to postexercise (from 188.1 ± 25.2 to 142.7 ± 29.7…