Brief report Frequency domain characteristics of ground reaction forces during walking of young and elderly females

Objective. To examine the frequency domain characteristics of the ground reaction forces of young and elderly females during free walking. Design. Independent t-tests were used to examine the frequency content of all three components of the ground reaction force. Background. Frequency domain analysis has the potential to assist in identifying changes in gait that may be masked in the time domain. No research has been done to identify changes in gait due to age-related impairments in the frequency domain. Methods. Ten young and ten elderly females walked at a prescribed speed while ground reaction forces were collected via a force platform. The highest frequency required to reconstruct the 99% of the signal’s power in each direction was calculated from the ground reaction forces. Results. The frequency content significantly decreased in the anterior–posterior direction for the young group. No significant differences were found for the other two directions (vertical and mediolateral) between the two groups. The elderly had a significantly higher frequency content compared with the young in the anterior–posterior direction. Conclusions. Ageing differences were detected using the frequency domain analysis for the anterior–posterior direction. It is possible that these differences were the result of the decrease in walking speed associated with the elderly group. Relevance Frequency domain analysis of the ground reaction forces is a useful addition to the gait analyst’s armamentarium especially when such changes are not obvious in the time domain. 2002 Elsevier Science Ltd. All rights reserved.