Department of Clinical and Experimental Sciences, University of Brescia Viale Europa, 11, 25123, Brescia, Italy.
Centre of Research on the Neuromuscular Function and the Adapted Motor Activity, University of Brescia Viale Europa, 11, 25123, Brescia, Italy.
Eur J Appl Physiol. 2023 Aug;123(8):1825-1836. doi: 10.1007/s00421-023-05198-0. Epub 2023 Apr 18.
During alternate movements across a joint, the changeover from one direction of rotation to the opposite may be influenced by the delay and rate of tension reduction and the compliance to re-lengthening of the previously active muscle group. Given the aging process may affect the above-mentioned factors, this work aimed to compare the dynamics of both the ankle torque decline and muscle re-lengthening, mirrored by mechanomyogram (MMG), in the tibialis anterior because of its important role in gait.
During the relaxation phase, after a supramaximal 35 Hz stimulation applied at the superficial motor point, in 20 young (Y) and 20 old (O) subjects, the torque (T) and MMG dynamics characteristics were measured.
The T and MMG analysis provided: (I) the beginning of the decay after cessation of stimulation (T: 22.51 ± 5.92 ms [Y] and 51.35 ± 15.21 ms [O]; MMG: 27.38 ± 6.93 ms [Y] and 61.41 ± 18.42 ms [O]); (II) the maximum rate of reduction (T: - 110.4 ± 45.56 Nm/s [Y] and - 52.72 ± 32.12 Nm/s [O]; MMG: - 24.47 ± 10.95 mm/s [Y] and - 13.76 ± 6.54 mm/s [O]); (III) the muscle compliance, measuring the MMG reduction of every 10% reduction of torque (bin 20-10%: 15.69 ± 7.5[Y] and 10.8 ± 3.3 [O]; bin 10-0%: 22.12 ± 10.3 [Y] and 17.58 ± 5.6 [O]).
Muscle relaxation results are different in Y and O and can be monitored by a non-invasive method measuring physiological variables of torque and re-lengthening dynamics at the end of the electromechanical coupling previously induced by the neuromuscular stimulation.
在关节的交替运动中，从一个旋转方向切换到相反方向可能会受到张力减小的延迟和速率以及先前活动肌肉群重新伸长的顺应性的影响。鉴于衰老过程可能会影响上述因素，本研究旨在比较由于其在步态中的重要作用而在前胫骨肌中由肌动描记图（MMG）镜像反射的踝力矩下降和肌肉再伸长的动力学。
在对浅表运动点施加 35 Hz 超刺激后的放松阶段，对 20 名年轻（Y）和 20 名老年（O）受试者测量了力矩（T）和 MMG 动力学特征。
T 和 MMG 分析提供了：（I）刺激停止后的衰减开始（T：22.51 ± 5.92 ms [Y]和 51.35 ± 15.21 ms [O]；MMG：27.38 ± 6.93 ms [Y]和 61.41 ± 18.42 ms [O]）；（II）最大减少率（T：-110.4 ± 45.56 Nm/s [Y]和-52.72 ± 32.12 Nm/s [O]；MMG：-24.47 ± 10.95 mm/s [Y]和-13.76 ± 6.54 mm/s [O]）；（III）肌肉顺应性，测量每 10%力矩减少时 MMG 的减少量（bin 20-10%：15.69 ± 7.5 [Y]和 10.8 ± 3.3 [O]；bin 10-0%：22.12 ± 10.3 [Y]和 17.58 ± 5.6 [O]）。
Y 和 O 之间的肌肉放松结果不同，可以通过一种非侵入性方法进行监测，该方法测量先前由神经肌肉刺激引起的机电耦合并在其结束时测量力矩和重新伸长动力学的生理变量。
