ACTN3 genotype influences exercise-induced muscle damage during a marathon competition.
Level 3 - non-randomized controlled study
Prospective observational cohort study comparing outcomes across genotype groups
PubMed 28154975 · doi:10.1007/s00421-017-3542-z
What was done
Seventy-one experienced runners completed a marathon race and were tested before and after the event. Researchers measured the ACTN3 R577X genotype, serum creatine kinase and myoglobin concentrations, maximal voluntary leg muscle power via countermovement jump, and self-reported lower limb muscle pain. Outcomes were compared between RR homozygotes and X allele carriers (RX heterozygotes and XX homozygotes grouped together).
What was found
Post-race, X allele carriers showed significantly greater increases in muscle damage markers and larger functional decrements than RR homozygotes: - Serum myoglobin: 774 ± 852 vs 487 ± 367 U L⁻¹ (P = 0.02) - Serum creatine kinase: 508 ± 346 vs 359 ± 170 ng mL⁻¹ (P = 0.04) - Pre-to-post-race leg muscle power reduction: -34.4 ± 16.1% vs -27.3 ± 15.4% (P = 0.05) - Muscle pain score: 7 ± 2 vs 6 ± 2 cm (P = 0.02)
Why it matters
This indicates that carrying the ACTN3 577X allele may heighten susceptibility to exercise-induced muscle damage and transient power loss during prolonged endurance events like a marathon.
Limits
The sample size is relatively small (n = 71), requiring RX and XX genotypes to be grouped together rather than assessed independently. Key potential confounders such as sex distribution, baseline training volume, pacing, finish times, and nutritional intake were not reported in the abstract.
Cited by
- supports Scientific research shows genetic variability in muscle damage susceptibility and recovery rates across individuals.