Evidence check: IgE Allergietest in the context of Sport

The ACTN3 gene test is often marketed to predict sprint vs. endurance ability. The rs1815739 (R577X) variant influences muscle fiber type: the R allele is associated with fast-twitch fibers (sprint), the X allele with slow-twitch fibers (endurance). However, effect sizes are small, and the test cannot reliably predict athletic performance. Training, nutrition, and environment are far more important. For a recreational runner, this test offers no actionable insight. The evidence is mechanistic (lab-based), not clinically predictive. False reassurance or self-limitation based on the result is unwarranted. Source: NCBI Gene ACTN3 (ID 89).