The purpose of this study was to clarify the characteristics of the gait function for the elderly with a special reference to the angle of the ankle joint and that of the metatarsophalangeal (MP) joint at heel contact and toe off. Five healthy young men (aged 22 to 23 yrs) and five healthy elderly men (aged 65 to 71 yrs) participated as the subjects in this study. The angle variation of the right ankle joint and that of the MP joint detected in goniometers were analyzed synchronously with the data of the force plate and the image data of bare foot movements during free, slow, and fast gait. The following results were obtained:
1. The walking speed, step length, and cadence for the elderly during free gait were significantly small. Furthermore, the step length of the elderly was shorter than that of the younger subject even with the same height. Moreover, it was found that the fluctuation in both the step length and cadence resulted in an fluctuation in walking speed.
2. One reason for the decrease in step length and cadence, and the increase in duration of the double supporting time for the elderly is the lowering of walking speed.
3. The angle of the ankle at heel contact, the angle of the ankle at toe off, and the angular displacement of the MP joint were significantly smaller for the elderly during free gait and during walking within a range of speeds. Also, the angle of the ankle at heel contact, and the angle of the ankle at toe off for young and elderly subjects were separated into two groups during walking within a range of speeds. It may be showed that the reason for the smallness of the angle of the ankle at heel contact and the angle of the ankle at toe off for the elderly irrespective of walking speed is due to an elderly behavior that unconsciously makes the angle smaller to prevent the danger of falling.
In conclusion, the difference in variables between young and elderly subjects during free gait and walking within a range of speeds exemplifies the characteristics of gait function for the elderly.