Mademli Lida, Arampatzis Adamantios
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Carl-Diem-Weg 6, D-50933 Cologne, Germany.
J Biomech. 2008;41(6):1229-35. doi: 10.1016/j.jbiomech.2008.01.019. Epub 2008 Mar 14.
Ageing is associated with a higher fatigue resistance during submaximal or maximal fatiguing contractions. The present study aimed to investigate the contribution of the central and peripheral fatigue to the age-related differences in fatigue development of the plantar flexor muscles. Therefore, the voluntary activation, rest twitch moment and voluntary plantar flexor moment were examined before during as well as 2, 5 and 10min after a fatiguing task. This consisted of intermittent isometric submaximal plantar flexor contractions at equal intensity for both young and old adults (considering the age-related differences in muscle inhibition). Consequently, possible differences between young and old adults in voluntary activation during the maximal contraction utilised for determining the intensity of the fatiguing task, which can influence fatigue development, have been taken into account. The plantar flexors moment was calculated using inverse dynamics and the voluntary activation was measured using the twitch interpolation technique. Changes in voluntary activation and rest twitch moment during the fatiguing task were used to assess central and peripheral fatigue, respectively. In both young and old adults, peripheral ( approximately 20%) as well as central fatigue ( approximately 9%) contributed to the time to task failure. Old adults demonstrated greater time to task failure than young ones, but similar voluntary activation behaviour during the fatiguing task. We concluded that, the age-related enhancement in fatigue resistance is not attributable to voluntary activation but is linked to mechanisms located within the working muscle.
衰老与次最大或最大疲劳收缩期间更高的抗疲劳能力有关。本研究旨在探讨中枢和外周疲劳对足底屈肌疲劳发展中与年龄相关差异的影响。因此，在疲劳任务之前、期间以及之后2分钟、5分钟和10分钟，对自愿激活、静息抽搐力矩和自愿足底屈肌力矩进行了检测。该任务包括年轻和老年成年人在相同强度下进行间歇性等长次最大足底屈肌收缩（考虑到与年龄相关的肌肉抑制差异）。因此，在用于确定疲劳任务强度的最大收缩过程中，年轻和老年成年人在自愿激活方面可能存在的差异已被考虑在内，而这种差异可能会影响疲劳发展。足底屈肌力矩通过逆动力学计算得出，自愿激活通过抽搐插值技术测量。疲劳任务期间自愿激活和静息抽搐力矩的变化分别用于评估中枢和外周疲劳。在年轻和老年成年人中，外周疲劳（约20%）以及中枢疲劳（约9%）都对任务失败时间有影响。老年人的任务失败时间比年轻人更长，但在疲劳任务期间的自愿激活行为相似。我们得出结论，与年龄相关的抗疲劳能力增强并非归因于自愿激活，而是与工作肌肉内的机制有关。
