Physical fatigue affects gait characteristics in older persons

Background. Fatigue affects self-reported functioning in older persons. Balance and gait problems increase fall risk. The effect of physical fatigue in the elderly population in general, and on balance control during walking in particular is not well known. This study investigates how a repeated sit-to-stand task affects gait control in older persons. Methods. Twenty-two persons (mean age 78 years) took part in a fatigue group (FG), and 22 persons (mean age 80 years) in a matched control group (CG). Participants walked back and forth on a walkway at different walking speeds. Gait data were adjusted for pretest-posttest differences in walking speed. The FG participants were physically fatigued by a repeated sit-to-stand task, Trunk data were obtained by a triaxial accelerometer and foot level data by an electronic walkway. Results. There were no group differences in preferred gait speed (p=.96) or in step length (p=.47) following the fatiguing task, but there were significant increases in step width (p=.023) and in mediolateral trunk acceleration amplitude (p=.038) in the FG group. Step-length variability (p=.004) and interstride trunk acceleration variability in the vertical direction (p=.002) increased, and tended to increase in the anteroposterior direction (p=.10) and to decrease in the mediolateral direction (p=.10) in the FG only. Conclusion. Gait changes following a physical fatiguing task agree with changes previously found in older persons at risk of falling, suggesting that physical fatigue may represent a risk factor for falls in elderly persons.