Harvey, Samuel B, Wadsworth, Michael, Wessely, Simon et al. · Psychosomatic medicine · 2008 · DOI
This study followed nearly 5,000 people from birth into their 50s to understand what causes ME/CFS. Researchers found that people who exercised more throughout their life—and continued exercising even as they felt increasingly tired—were more likely to develop ME/CFS later on. The study suggests that continuing to push yourself physically while experiencing growing fatigue may play a role in developing this condition.
This study challenges the deconditioning hypothesis and provides prospective evidence that high physical activity levels and persisting with exercise despite fatigue may contribute to ME/CFS development. Understanding behavioral and lifestyle risk factors is crucial for identifying patients at risk and informing management strategies that prioritize pacing over pushing through symptoms.
This study does not prove that exercise causes ME/CFS; the association may reflect reverse causality, selection bias, or unmeasured confounders such as personality traits or genetic predisposition. The study cannot establish that exercise avoidance prevents ME/CFS or that the exercise-fatigue pattern is mechanistic rather than correlational. Single self-reported CFS diagnosis at age 53 lacks rigorous case definition validation, and the low prevalence (1.1%) limits generalizability.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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