Enhanced physiological tremor deteriorates plantar flexor torque steadiness after bed rest

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• 作者：Edwin R. Mulder^a ; ^b ; ^c ; ^{Edwin.Mulder@dlr.de} ; Astrid M. Horstman^b ; Karin Gerrits^b ; Mark Massa^c ; Bert U. Kleine^c ; Arnold de Haan^b ; ^d ; Daniel L. Belavý ; ^e ; Dieter Felsenberg^e ; Machiel Zwarts^f ; Dick F. Stegeman^b ; ^c [Author vitae]
• 关键词：Bed rest ; Triceps surae ; Torque fluctuation ; BBR2 ; H-reflex
• 刊名：Journal of Electromyography and Kinesiology
• 出版年：2011
• 出版时间：April 2011
• 年：2011
• 卷：21
• 期：2
• 页码：384-393
• 全文大小：991 K

文摘

This study evaluated the effectiveness of resistance training to preserve submaximal plantar flexor (PF) torque steadiness following 60 days of bed rest (BR). Twenty-two healthy male subjects underwent either BR only (CTR, n = 8), or BR plus resistance training (RT, n = 14). The magnitude of torque fluctuations during steady submaximal isometric PF contractions (20 % , 40 % , 60 % and 80 % of maximum) were assessed before and after BR. Across contraction intensities, torque fluctuations (coefficient of variation, CV) increased more (P < 0.05) after BR for CTR (from 0.31 ± 0.10 to 0.92 ± 0.63; P < 0.001), than for RT (from 0.30 ± 0.09 to 0.54 ± 0.27; P < 0.01). A shift in the spectral content of torque fluctuations towards increased rhythmic activity between 6.5 and 20 Hz was observed in CTR only (P < 0.05). H-reflex amplitude (H_max/M_max ratio) declined across groups from 0.57 ± 0.18 before BR to 0.44 ± 0.14 following BR (P < 0.01) without correlation to CV. The present study showed that increased torque fluctuation after BR resulted from enhanced physiological tremor. Resistance training prevented the spectral shift in isometric PF torque fluctuation and offset 50 % of the decline in performance associated with long-term BR.