Lay opinion vs evidence: Sportgene Training

The lay opinion that a genetic test can predict athletic talent or the optimal training method is widespread. However, scientific evidence shows that most 'sport genes' offered in direct-to-consumer tests (e.g., ACTN3, PPARG, ADRB2) have only very small effects on performance or training adaptation. GWAS studies identify associations, but effect sizes are small and results are often not replicated. For example, the PPARG Pro12Ala variant (rs1801282) is linked to slightly improved insulin sensitivity, but its impact on endurance performance is minimal and far outweighed by training and diet. The ADRB2 Gln27Glu variant (rs1042714) shows weak associations with body fat percentage and VO2max, but no clinical relevance for training prescription. The HFE H63D variant (rs1799945) affects iron regulation, but only a small fraction of carriers develop iron overload; for athletes, a ferritin test is more useful than genetic interpretation. In summary, the evidence for sport genetic testing is mostly at the GWAS level with small effects. Lay opinions greatly overestimate predictive power. Responsible use requires clear communication of limitations and avoidance of exaggerated promises.