Neuromuscular determinants of explosive torque: Differences among strength-trained and untrained young and older men.

Autor: Orssatto LBR; School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia.; Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia., Wiest MJ; Neural Engineering & Therapeutic Team, KITE, Toronto Rehab, University Health Network, Toronto, ON, Canada., Moura BM; Biomechanics Laboratory, Federal University of Santa Catarina, Florianópolis, Brazil., Collins DF; Human Neurophysiology Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, AB, Canada., Diefenthaeler F; Biomechanics Laboratory, Federal University of Santa Catarina, Florianópolis, Brazil.
Jazyk: angličtina
Zdroj: Scandinavian journal of medicine & science in sports [Scand J Med Sci Sports] 2020 Nov; Vol. 30 (11), pp. 2092-2100. Date of Electronic Publication: 2020 Aug 25.
DOI: 10.1111/sms.13788
Abstrakt: This study compared the differences in neural and muscular mechanisms related to explosive torque in chronically strength-trained young and older men (>5 years). Fifty-four participants were allocated into four groups according to age and strength training level: older untrained (n = 14; 65.6 ± 2.9 years), older trained (n = 12; 63.6 ± 3.8 years), young untrained (n = 14; 26.2 ± 3.7 years), and young trained (n = 14; 26.7 ± 3.4 years). Knee extension isometric voluntary explosive torque (absolute and normalized as a percentage of maximal voluntary torque) was assessed at the beginning of the contraction (ie, 50, 100, and 150 ms-T50, T100, and T150, respectively), and surface electromyogram (sEMG) amplitude (normalized as a percentage of sEMG recorded during maximal voluntary isometric contraction) at 0-50, 50-100, and 100-150 time windows. Supramaximal electrically evoked T50 was assessed with octet trains delivered to the femoral nerve (8 pulses at 300 Hz). Voluntary T50, T100, and T150 were higher for trained than untrained in absolute (P < 0.001) and normalized (P < 0.030) terms, accompanied by higher sEMG at 0-50, 50-100, and 100-150 ms (P < 0.001), and voluntary T50/octet T50 ratio for trained. Greater octet T50 was observed for the young trained (P < 0.001) but not for the older trained (P = 0.273) compared to their untrained counterparts. Age effect was observed for voluntary T50, T100, and T150 (P < 0.050), but normalization removed these differences (P > 0.417). Chronically strength-trained young and older men presented a greater explosive torque than their untrained pairs. In young trained, the greater explosive performance was attributed to enhanced muscular and neural mechanisms, while in older trained to neural mechanisms only.
(© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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