Polygenic Profile and Exercise-Induced Muscle Damage by a Competitive Half-Ironman.
Level 4 - case-series / case-control
Small observational cohort study without a non-exposed control group
PubMed 29140910 · doi:10.1519/JSC.0000000000002303
What was done
Twenty-two experienced triathletes were assessed before and after a competitive half-Ironman. Venous blood samples were collected pre- and post-race to measure serum creatine kinase (CK) and myoglobin. Seven candidate single-nucleotide polymorphisms (ACE Ins/Del, ACTN3 R577X, CKM NcoI, IGF2 C13790G, IL6 174G>C, MLCK C37885A, and TNF-alpha 308G>A) were genotyped to calculate an aggregate total genotype score. Participants were categorized into low CK responders (n = 10) and high CK responders (n = 12) based on post-race serum CK levels.
What was found
Low CK responders had a mean post-race CK of 377 ± 86 U/L compared to 709 ± 136 U/L in high CK responders. Low responders exhibited lower post-race serum myoglobin (384 ± 243 vs. 597 ± 293 ng/ml, p = 0.04) and a higher total genotype score (7.7 ± 1.1 vs. 5.5 ± 1.1 points, p < 0.01). Groups did not differ significantly in age, anthropometrics, or training habits.
Why it matters
This study provides preliminary evidence that a combined profile of candidate polymorphisms related to muscle structure and inflammation may explain individual variation in exercise-induced muscle damage during endurance competitions.
Limits
The sample size was very small (n = 22), carrying a high risk of statistical imprecision and false-positive genetic associations. The study was restricted to seven candidate SNPs rather than a genome-wide approach, and race-day confounders such as exact pacing, nutrition, and hydration were not controlled.
Cited by
- supports Scientific research shows genetic variability in muscle damage susceptibility and recovery rates across individuals.