Neural Adjustment in the Activation of the Lower Leg Muscles through Daily Physical Exercises in Community-Based Elderly Persons

Abstract

Reflecting the rapidly aging population, community-based interventions in the form of physical exercise have been introduced to promote the health of elderly persons. Many investigation studies have focused on muscle strength in the lower leg as a potent indicator of the effect of physical exercises. The objective of this study was to assess the effect of long-term daily exercises on neural command in lower leg muscle activations. Twenty-six community-based elderly persons (13 men and 13 women; 69.8 ± 0.5 years old) participated in this study. Daily exercise was comprised of walking for more than 30 min, stretching, muscle strengthening and balance exercise, and was continued for three months. Muscle strength and surface electromyography of the tibia anterior, rectus femoris, and biceps femoris were measured in maximum isometric voluntary contraction both before and after the intervention. The mean frequency of the firing of motor units was calculated based on fast Fourier transformation of the electromyography. As the results of the intervention, muscle strength increased significantly only in biceps femoris, whereas the mean frequency of motor units decreased significantly in every muscle, indicating that motor unit firing in lower frequency efficiently induces the same or greater strength compared with before the intervention. Thus, synchronization of motor units compensates for the lower frequency of motor unit firing to maintain muscular strength. In conclusion, long-term physical exercises in the elderly can modulate the neural adjustment of lower leg muscles to promote efficient output of muscle strength. electromyography; elderly person; physical exercise

Effect of long‐term, community‐based daily exercise on the ability to control the dynamic standing balance of Japanese elderly persons in relation to falls

“…The effect of 3 months of community‐based physical exercise, including daily walking and comprehensive exercises, on the neural adjustment of the standing balance and the accompanying muscular activation of Japanese elderly persons has been reported previously (Maejima et al. , 2007; 2008).…”

“…The Health‐up Model Project, scheduled by the All Japan Federation of National Health Insurance Organization, started in 2001 (Maejima et al. , 2007; 2008).…”

“…The effect of 3 months of community-based physical exercise, including daily walking and comprehensive exercises, on the neural adjustment of the standing balance and the accompanying muscular activation of Japanese elderly persons has been reported previously (Maejima et al, 2007;. The standing balance is classified into three hierarchical phases: static standing balance, dynamic standing balance, and postural response (Shumway-Cook & Horak, 1990;Uchiyama, 2001).…”

“…The Health-up Model Project, scheduled by the All Japan Federation of National Health Insurance Organization, started in 2001 (Maejima et al, 2007;. One of the main purposes of this project was to prevent adult disease by promoting physical exercise.…”

Recurrence quantification analysis of motor learning and training

“…Surface electromyography (sEMG) signals play a significant role in rehabilitation [18,19] or any measurement of muscular activity. The first use of EMG system can be dated back to 1912 by H. Piper, who used a string of galvanometers [2].…”