Power Training in Older Adults: From Neurophysiology / Neuromechanics to Daily Live

65岁及以上人群每年跌倒的发生率约为35%，80岁以上人群每年跌倒的发生率增加至50%以上。大约80%的跌倒可能是由与年龄相关的运动功能丧失相关的内在因素造成的，这些运动功能丧失是由于运动单元的丧失、纤维类型成分的改变、神经肌肉激活减少和肌肉激活速度减慢。包括体育锻炼在内的积极生活方式可以部分抵消与年龄相关的神经肌肉系统变化。从功能角度看，最大强度、力发展速度与体位控制之间存在正相关。然而，在老年人中，既没有发现最佳的运动量和强度组合，也没有发现并行训练方案的潜在神经生理机制。对年轻人的实验研究表明，高负荷的力量训练增加了最大力量的产生，从而增加了力量的发展速度，而小负荷和最大运动速度的力量训练只增加了力量的发展速度。潜在的生理影响以及老年人的机体是否以同样的方式作出反应尚未得到充分的记录，这是本项目的主要目的。在此背景下，以下研究设计可以产生大量有用的知识：30名成年人（50 - 65岁，性别平均），将通过并行化（标准是性别和最大力量产生）分为两个干预组，将以每周三次的频率锻炼背屈肌，为期12周。一组（Tpower）将进行一项力量训练计划，5组8次重复，强度为个人最大单次重复（1RM）的30%至40%，每组之间休息3分钟，而第二组（力量）将进行一项训练计划，6组6次重复，强度为1RM的80%，每组之间休息3分钟。通过生物力学测量，运动诱导的适应性将被捕获，神经生理学技术将揭示潜在的机制。胫骨前肌单个运动单元的电生理特征将通过细丝电极确定。此外，将确定胫骨前肌、比目鱼肌和腓肠肌内侧肌的表面肌电图数据，并使用力传感器识别所产生的扭矩。

The incidence of falls per year in the population aged 65 years and older is around 35% and increases for persons older than 80 years to more than 50%. Around 80% of those falls could result from intrinsic factors related to the age-related loss of motor function due to a loss of motor units, changes in fibre type compositions, reduced neuromuscular activation, and a slowed rate of muscle activation. An active life style including physical exercises can partly counteract the age-related alterations of the neuromuscular system. From a functional point of view, a positive correlation between maximal strength respectively rate of force development and postural control exists. However, neither the optimal combination of exercise volume and intensity nor the underlying neurophysiological mechanisms of the concurrent training regimen have been revealed in the elderly. Experimental studies with young adults have shown that strength training with higher loads increases maximal force production and thereby rate of force development, whereas strength training with smaller loads and maximal movement velocity only increases rate of force development. The underlying physiological effects and if elderly persons organisms respond in the same way has not been fully documented and is the main purpose of this project. The following research design can yield a substantial amount of useful knowledge in this context: 30 adults (> 65 years, genders divided equally), who will be split into two intervention groups through parallelization (criteria will be gender and maximal force production), will exercise their dorsiflexor muscles for a period of 12 weeks at a frequency of three sessions per week. One group (Tpower) will perform a power training program with 5 sets of 8 repetitions at an intensity of 30% to 40% of their individual one repetition maximum (1RM) and 3 minutes of rest between the sets, whereas the second group (Tstrength) will perform a training program with 6 sets of 6 repetitions at an intensity of 80% of 1RM and 3 minutes of rest between the sets. By means of biomechanical measurements the exercise-induced adaptations will be captured and neurophysiological techniques will reveal the underlying mechanisms. The electrophysiological characteristics of single motor units of tibialis anterior will be determined via fine-wire electrodes. Further, surface-electromyographic data of tibialis anterior, soleus, and gastrocnemius medialis will be determined and the resultant torque will be identified using force transducers.