ACE ID genotype and the muscle strength and size response to unilateral resistance training.
Level 3 - non-randomized controlled study
Prospective cohort / non-randomized intervention trial evaluating genetic association
PubMed 16775548 · doi:10.1249/01.mss.0000222835.28273.80
What was done
631 young adult men (42%) and women (58%; 80% white; mean age 24.2 years) completed a 12-week (2 sessions/week) unilateral upper-arm resistance training program in their non-dominant arm, with the dominant arm serving as an untrained control. Participants were genotyped for the ACE insertion/deletion (I/D) polymorphism (23.1% II, 46.1% ID, 30.8% DD). Pre- and post-training peak elbow flexor isometric strength (MVC), one-repetition maximum (1RM), and biceps muscle cross-sectional area (CSA via MRI) were evaluated across genotypes using ANCOVA models.
What was found
Baseline muscle size and strength did not differ significantly by ACE genotype. In the trained arm, MVC gains were larger in II/ID carriers compared to DD carriers (22% vs. 17%, P < 0.05), whereas 1RM gains (51%) and CSA gains (19%) did not differ by genotype (P >= 0.05). In the untrained contralateral arm, MVC increased in II/ID (7%, P < 0.001) but not in DD (2%, P >= 0.05), whereas 1RM and CSA gains were higher in DD/ID than II carriers (1RM: 11% vs. 7%; CSA: 2% vs. -0.1%, P < 0.05). Overall, ACE genotype accounted for approximately 1% of the MVC response in the trained arm, and 2% of MVC, 2% of 1RM, and 4% of CSA response in the untrained arm.
Why it matters
This study shows that while the ACE I/D polymorphism is statistically associated with training responses and contralateral strength transfer, its practical impact is very small, explaining only 1–4% of the phenotypic variance.
Limits
The study was conducted primarily in young, predominantly white (80%) individuals, limiting generalizability to older or ethnically diverse populations. The abstract provides no data on nutritional control, adherence rates, or potential candidate gene interactions, and the observed genetic variance explained is too minor to guide personalized exercise prescription.
Cited by
- context Genetic variations in the angiotensin-converting enzyme (ACE) gene determine whether an individual responds better to single-set versus multiple-set lower-body resistance training.