Evidence of nonlocal muscle fatigue in male youth.
Evidence for nonlocal muscle fatigue (NLMF) has been inconsistent in adults, with no studies investigating youth. The objective was to examine NLMF in youth. Forty-two young males (age, 10-13 years) were tested for maximal voluntary isometric contraction (MVIC) force of the ipsilateral and contralateral knee extensors at 90° and 120° knee flexion, elbow flexors at 90°, handgrip, knee extensor isokinetic torque (300°·s-1analyzed at 90° and 120° knee flexion), as well as a unilateral countermovement jump (CMJ) and Y Balance test (YBT). Isokinetic fatigue group (n = 15) had unilateral fatigue induced with 10 sets of 20 repetitions of maximal isokinetic knee extensor contractions at 300°·s-1. Isometric fatigue group (n = 15) used 10 repetitions of 6-s knee extensor MVIC whereas the control group (n = 12) were not fatigued. There was no significant difference in the response to the isometric- or isokinetic-fatigue intervention protocols. Main time effects indicated that NLMF was evident with the contralateral knee extensor MVIC at 90° (p = 0.008; 8.9%), knee extensor isokinetic torque at 90° (p < 0.001; 11.4%), and 120° (p = 0.05; 5.4%), CMJ (p = 0.02; 11.5%), handgrip (p = 0.06; 4.5%), elbow flexors (p < 0.001; 7.7%), and YBT (p = 0.001; 5.6%). Ipsilateral NLMF deficits occurred with handgrip (p < 0.001; 7.3%), elbow flexors MVICs (p < 0.001; 10.7%), CMJ (p = 0.02; 12.2%), and YBT (p = 0.002; 3.8%). NLMF with similar relative fatigue-induced deficits of fatigued and nonfatigued limbs suggest that youth fatigue is highly dependent upon the extent of activation or inhibition of the nervous system. Coaches of young athletes might consider developing technical motor skills before fatiguing exercise components, which might hinder the proficiency of their performance.
a Tunisian Research Laboratory "Sport Performance Optimization", National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.
Aymen
A
Ben Othman
a Tunisian Research Laboratory "Sport Performance Optimization", National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.|c Sports Performance Research Institute, AUT University, Auckland, New Zealand.
Anis
A
Chaouachi
a Tunisian Research Laboratory "Sport Performance Optimization", National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.
Raouf
R
Hammami
a Tunisian Research Laboratory "Sport Performance Optimization", National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.
Mehdi M
MM
Chaouachi
a Tunisian Research Laboratory "Sport Performance Optimization", National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.
Sofien
S
Kasmi
b Memorial University of Newfoundland, School of Human Kinetics and Recreation, St. John's, NL A1C 5S7, Canada.
David G
DG
Behm
D000293:Adolescent; D002648:Child; D004550:Elbow / Q000502:physiology; D005080:Exercise Test; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007717:Knee / Q000502:physiology; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology; D012959:Socioeconomic Factors; D019415:Torque
balance; children; crossover fatigue; enfants; fatigue croisée; isokinetic; isokinétique; spécificité de l’entraînement; training specificity; équilibre