Muscle endurance & self-perceived fatigue predict decline in gait speed and activities of Daily Living after one year follow-up: results from the BUTTERFLY Study

BACKGROUND: Fatigue might influence the losses in activities of daily living (ADL). When fatigue parameters are present before the experience of losses in ADL and gait speed they can be used as early warning signals. This study aimed to explore the predictive value of muscle endurance and fatigue on changes in ADL and gait speed in community-dwelling older adults aged 80 and over.

METHODS: 324 community-dwelling older adults aged 80 and older of the BUTTERFLY study were assessed after one year for muscle endurance, self-perceived fatigue, Activities of Daily Living and gait speed. Exploratory factor analysis (EFA) was performed to explore, whether there is an underlying arrangement of the fatigue parameters. Mediating logistic regression analyses were used to investigate whether muscle endurance mediated by self-perceived fatigue predicts decline in gait speed and ADL after one year follow-up.

RESULTS: Exploratory factor analysis indicated a 2-factor model (muscle endurance factor and self-perceived fatigue factor) and had a moderate fit (X 2: 374.81, df: 2, CFI; 0.710, TLI: 0.961, RSMEA(90%): 0.048 (0.00-0.90)). Muscle endurance mediated by self-perceived fatigue had an indirect effect on the prediction of decline in Basal- (-0.27), Instrumental-ADL (-0.25) and gait speed (-0.28) after one year follow-up.

CONCLUSION: This study showed that low muscle endurance combined with high self-perceived fatigue can predict changes in ADL after one-year follow-up. These parameters might be very suitable for use in evaluating intrinsic capacity and can help to reduce the limitations in clinical usage of the vitality domain in the framework of intrinsic capacity.