ABSTRACT
This study investigated the effects of exercise intervention with a 12-week slightly-weighted shoe on lower-limb skeletal muscle and gait patterns in the elderly. A total of 29 healthy elderly Japanese who had irregular walking habits were randomly assigned to either slightly-weighted-shoe (WS group, n = 14; Age, 70.6 ± 5.7 years; WS, 493 g) or normal-shoe (NS group, n = 15; Age, 69.3 ± 6.9 years; NS, 293 g) intervention groups. The participants were instructed to maintain their normal daily physical activity (PA) during the intervention period. Segmental intracellular water (ICW) and muscle thickness (MT) were measured as an index of skeletal muscle mass in the lower limb, and kinematic gait data were acquired by motion analysis. Walking stability was assessed as a standard deviation of the vertical fluctuation in whole-body center of mass (COM fluctuation). The daily PA was monitored using an accelerometer and an activity record. ICW in the upper leg and MT of rectus femoris increased significantly in the WS group compared with the NS group (ICW: 13.8% vs. 2.2%, MT: 12.1% vs. 1.3%), while COM fluctuation was significantly reduced in the WS group (p<0.05) during normal walking. The present study demonstrated that interventions with a slightly-weighted-shoe may be able to increase muscle volume in the upper leg and change gait patterns in the healthy elderly.
ABSTRACT
Although skeletal muscle mass decreases with aging, its decrease rate may differ among parts of the body. There have been few studies examining the differences in the muscle mass decrease rate between proximal and distal parts of the limbs or between the left and right legs in a large population. Bioelectrical impedance (BI) index, calculated as the ratio of the square of segment length to impedance, is linearly correlated with the muscle mass calculated by MRI (r=0.902-0.976, p<0.05, Miyatani et al., 2001) in the limb segments. The purpose of this study was to examine differences in the decrease rate of muscle mass between the proximal and distal parts of the limbs and between the upper and lower limbs in healthy Japanese. The BI index was measured in the bilateral thighs, lower legs, upper arms, and forearms of 1006 healthy Japanese men and women (aged 15-97 years). While the BI index decreased with aging in all examined parts of the body, the decrease rate was larger in the lower limb than in the upper limb, and in the thigh than in the lower leg. The percentage of people who showed a difference of more than 10 % in the BI index between the left and right lower limbs was significantly higher in the elderly than in young subjects. These differences in the decrease rate of muscle mass between limbs may be associated with decreases in physical functions in the elderly.