Myths vs facts: Fitness | LifestyleCheck and sleep

Myth: A DNA test or LifestyleCheck can accurately predict your fitness potential (sprint vs. endurance) or sleep quality. Fact: Genetic variants like ACTN3 and ACE have very small effect sizes (1.5–2.5% variance) and are not deterministic. Training, diet, sleep hygiene, and environment dominate. A single cortisol test is unreliable due to circadian fluctuations. Many DTC claims are marketing. Evidence is mixed: GWAS data exist but clinical utility is low. Safety note: Do not base training or supplement decisions solely on such tests. Consult a doctor for sleep issues.