Is TSH useful for Sport?

TSH (thyroid-stimulating hormone) is a clinical marker for thyroid function, not a sport-specific biomarker. In athletes, undiagnosed hypothyroidism (elevated TSH) can cause fatigue, reduced endurance, and slower recovery. Observational studies suggest that even subclinical hypothyroidism may impair exercise capacity. However, in healthy, asymptomatic athletes, TSH is rarely abnormal and does not directly predict VO2max or sprint performance. The evidence is based on human observational studies and clinical practice, not on randomized sport interventions. A TSH test is useful when symptoms like persistent tiredness, cold intolerance, or unexplained weight gain are present. For recreational athletes, routine TSH screening without clinical indication lacks strong evidence. MyBody-X may include TSH in blood panels, but interpretation requires a physician. Conclusion: TSH is useful for ruling out thyroid disorders that affect sport performance, but it is not a training optimization tool. The evidence level is moderate and context-dependent.