Gait Adaptations Following Exercise-Induced Muscle Fatigue in Older Adults: Awareness and Intentionality

Exercise-induced muscle fatigue can affect older people's gait and hence their fall risk. However, when fatigued, non-homogeneous changes in gait have been shown, questioning whether these are caused by a direct effect of fatigue or compensatory strategies to account for (perceptions of) fatigue. This study aims to determine if older adults are (congruently) aware of gait alterations after exercise, and whether these alterations are (un)intentional.

We conducted a convergent mixed-methods study with eighteen healthy older adults (76 years (SD 4.95), 13 females). Participants performed a paradigm of twenty repetitive sit-to-stand exercises, alternated with in-between 15-m walking trails until participants reached a rating of perceived exertion of 9 out of 10 or when 25 minutes had passed. Gait was unknowingly assessed using THEIA Markerless motion capture during the entire fatiguing protocol and analysed on group and individual level using Generalized Estimating Equations and independent samples tests respectively. Directly after the fatiguing protocol, participants were interviewed on self-perceived changes in gait. Whether older adults’ self-perceived changes in gait were (un)intentional was qualitatively analysed.

In most individuals, gait speed, step length, and anterior-posterior margin of stability significantly changed after the fatiguing protocol. The few intentional gait alterations seem to be based upon the context, experience, or education. Furthermore, while most participants reported an unintentional lower gait speed and decreased stability in the fatigued walking condition, convergent analysis showed that perceptions were generally incongruent with objective data. This misperception of gait alterations could play a role in older adults’ risk for falling when fatigued.