How are ACTN3 and Müdigkeit related?

The relationship between ACTN3 and fatigue is not clearly established in the scientific literature. ACTN3 encodes α-actinin-3, a structural protein in fast-twitch muscle fibers. The common R577X variant results in a loss of functional protein. Some studies suggest that individuals with the X-allele (ACTN3 deficiency) may experience reduced muscle power and faster fatigue during high-intensity activities, but also better endurance performance. The evidence is based on association studies with small effect sizes. A direct causal link to general fatigue (e.g., daily tiredness) is lacking. Consumer DNA tests like MyBody-X can detect this variant, but the clinical relevance for fatigue is low. Interpretation should be cautious, as many other factors (sleep, diet, stress) dominate. There are no evidence-based recommendations for diet or supplementation based on ACTN3.