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Advisor(s)
Abstract(s)
The objective of the study was to investigate the
effect of strength and endurance training on muscle fiber membrane properties and discharge rates of low-threshold motor units of the
vasti muscles during fatiguing contractions. Methods: Twenty-five sedentary healthy men (age (mean T SD) = 26.3 T 3.9 yr) were
randomly assigned to one of three groups: strength training, endurance training, or a control group. Conventional endurance and strength
training was performed 3 dIwkj1, during a period of 6 wk. Motor unit conduction velocity and EMG amplitude of the vastus medialis
obliquus and lateralis muscles and biceps femoris were measured during sustained isometric knee extensions at 10% and 30% of the
maximum voluntary contraction before and immediately after training. Results: After 6 wk of training, the reduction in motor unit conduction
velocity during the sustained contractions at 30% of the maximum voluntary force occurred at slower rates compared with baseline
(P G 0.05). However, the rate of decrease was lower after endurance training compared with strength training (P G 0.01). For all groups,
motor unit discharge rates declined during the sustained contraction (P G 0.001), and their trend was not altered by training. In addition, the
biceps femoris–vasti coactivation ratio declined after the endurance training. Conclusions: Short-term strength and endurance training
induces alterations of the electrophysiological membrane properties of the muscle fiber. In particular, endurance training lowers the rate
of decline of motor unit conduction velocity during sustained contractions more than strength training
Description
Keywords
EMG Fatigue Submaximal contractions Endurance training Strength training
Citation
Vila-Chã, Carolina; Falla, Deborah; Correia, Miguel Velhote; Farina, Dario (2012). Adjustments in motor unit properties during fatiguing contractions after training. Medicine and Science in Sports and Exercise. ISSN 0195-9131. 44:4, p. 616-624
Publisher
Lippincott Williams & Wilkins