Is Fatigue Associated With Aerobic Capacity and Muscle Strength in People With Multiple Sclerosis: A Systematic Review and Meta-analysis

Objective: To determine the relationship between self-reported fatigue and aerobic capacity and muscle strength in people with multiple sclerosis (MS).

Data sources: Four databases (Cumulative Index to Nursing and Allied Health, MEDLINE, ProQuest, and Web of Science Core Collections) were searched up to October 2018.

Study selection: Cross-sectional or longitudinal studies that reported the association between self-reported fatigue and aerobic capacity or objectively measured muscle strength in people with MS were included.

Data extraction: Study details, participant demographics, outcome measurement protocols, and the correlation coefficient derived from the association between fatigue and aerobic capacity or muscle strength at baseline was extracted, and methodological quality of included studies was assessed using the Joanna Briggs Institute Appraisal Checklist for Analytical Cross-sectional Studies.

Data synthesis: Ten studies were identified, of which 5 examined the association between fatigue and aerobic capacity and 7 examined the association between fatigue and muscle strength. Meta-analysis of the extracted correlation coefficients was performed using the Hedges-Olkin method, and pooled correlation coefficients demonstrated a moderate negative association between fatigue and aerobic capacity (r=-0.471; 95% CI, -0.644 to -0.251; P<.001) and a weak negative association between fatigue and muscle strength (r=-0.224; 95% CI, -0.399 to -0.032; P=.022).

Conclusions: The results of this meta-analysis suggest that higher levels of aerobic capacity are associated with lower fatigue. Therefore, this finding highlights the potential role of aerobic exercise interventions in managing fatigue. Conversely, the relationship between fatigue and muscle strength was weak and inconsistent, and further studies are required to examine the association between these variables.