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

65岁及以上人口每年跌倒的发生率约为35%，80岁以上人口的跌倒发生率增加到50%以上。其中约80%的跌倒可能是与运动单位丧失、纤维类型成分改变、神经肌肉活性降低和肌肉激活速度减慢有关的与年龄相关的运动功能丧失有关的内在因素。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的变化。从机能角度看，最大力量、力量发展速度与姿势控制之间存在正相关关系。然而，在老年人中，既没有揭示运动量和强度的最佳组合，也没有揭示同时训练方案的潜在神经生理机制。对年轻人的实验研究表明，高负荷力量训练可以提高最大力量产量，从而提高力量发展速度，而小负荷力量训练和最大运动速度只会提高力量发展速度。潜在的生理影响以及老年人的生物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。以下研究设计可以在这方面产生大量有用的知识：30名成年人(65岁，性别平均)，将通过平行试验分为两个干预组(标准将是性别和最大力量产生)，将以每周三次会议的频率锻炼他们的背屈肌，为期12周。其中一组(Tpower)将以其个人最大1次重复(1Rm)的30%至40%的强度进行5组8次重复的力量训练计划，并在两组之间休息3分钟，而第二组(Tpower)将以1 Rm的80%的强度进行6组6次重复的训练计划，并在两组之间休息3分钟。通过生物力学测量将捕捉到运动诱导的适应，神经生理学技术将揭示其潜在的机制。将通过细丝电极测定胫骨前肌单个运动单位的电生理特性。此外，将测定胫骨前肌、比目鱼肌和腓肠肌内侧肌的表面肌电数据，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.