Adjustments in motor unit properties during fatiguing contractions after training

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Adjustments in motor unit properties during fatiguing contractions after training. / Vila-Chã, Carolina; Falla, Deborah; Correia, Miguel Velhote; Farina, Dario.

In: Medicine and Science in Sports and Exercise, Vol. 44, No. 4, 04.2012, p. 616-24.

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Vila-Chã, Carolina ; Falla, Deborah ; Correia, Miguel Velhote ; Farina, Dario. / Adjustments in motor unit properties during fatiguing contractions after training. In: Medicine and Science in Sports and Exercise. 2012 ; Vol. 44, No. 4. pp. 616-24.

Bibtex

@article{89fa91d8d0d441c18c2c4ceb3f430f12,
title = "Adjustments in motor unit properties during fatiguing contractions after training",
abstract = "OBJECTIVE: 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 ± SD) = 26.3 ± 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 d·wk⁻¹, 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 < 0.05). However, the rate of decrease was lower after endurance training compared with strength training (P < 0.01). For all groups, motor unit discharge rates declined during the sustained contraction (P < 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.",
keywords = "Adult, Electromyography, Electrophysiological Phenomena, Humans, Knee, Male, Muscle Contraction, Muscle Fatigue, Muscle, Skeletal, Physical Endurance, Recruitment, Neurophysiological, Resistance Training, Young Adult, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't",
author = "Carolina Vila-Ch{\~a} and Deborah Falla and Correia, {Miguel Velhote} and Dario Farina",
year = "2012",
month = apr,
doi = "10.1249/MSS.0b013e318235d81d",
language = "English",
volume = "44",
pages = "616--24",
journal = "Medicine and Science in Sports and Exercise",
issn = "0195-9131",
publisher = "American College of Sports Medicine",
number = "4",

}

RIS

TY - JOUR

T1 - Adjustments in motor unit properties during fatiguing contractions after training

AU - Vila-Chã, Carolina

AU - Falla, Deborah

AU - Correia, Miguel Velhote

AU - Farina, Dario

PY - 2012/4

Y1 - 2012/4

N2 - OBJECTIVE: 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 ± SD) = 26.3 ± 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 d·wk⁻¹, 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 < 0.05). However, the rate of decrease was lower after endurance training compared with strength training (P < 0.01). For all groups, motor unit discharge rates declined during the sustained contraction (P < 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.

AB - OBJECTIVE: 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 ± SD) = 26.3 ± 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 d·wk⁻¹, 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 < 0.05). However, the rate of decrease was lower after endurance training compared with strength training (P < 0.01). For all groups, motor unit discharge rates declined during the sustained contraction (P < 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.

KW - Adult

KW - Electromyography

KW - Electrophysiological Phenomena

KW - Humans

KW - Knee

KW - Male

KW - Muscle Contraction

KW - Muscle Fatigue

KW - Muscle, Skeletal

KW - Physical Endurance

KW - Recruitment, Neurophysiological

KW - Resistance Training

KW - Young Adult

KW - Journal Article

KW - Randomized Controlled Trial

KW - Research Support, Non-U.S. Gov't

U2 - 10.1249/MSS.0b013e318235d81d

DO - 10.1249/MSS.0b013e318235d81d

M3 - Article

C2 - 21904248

VL - 44

SP - 616

EP - 624

JO - Medicine and Science in Sports and Exercise

JF - Medicine and Science in Sports and Exercise

SN - 0195-9131

IS - 4

ER -