Ace I/d Polymorphism Alters The Muscle Strength Response To Resistance Training

Abstract

PURPOSE The Angiotensin Converting Enzyme Insertion allele (ACE I) is favorably associated with endurance performance, whereas the ACE Deletion allele (ACE D) with muscle strength and power-oriented performance. The purpose of this study was to examine if the ACE I/D polymorphism was related to the muscle strength and size responses to a unilateral, upper arm resistance training (RT) program among apparently healthy, young adults. We hypothesized the ACE D allele would be associated with greater increases in muscle strength and size than the ACE I allele. METHODS Subjects were 620 (mean ± SEM, 24.5±1.7 yr) mostly white (80%), mean (42%) and women (58%) who had not performed RT in the previous yr. Subjects completed 12 wk (2 d/wk) of supervised upper-arm RT. Peak elbow flexor muscle strength (kg) was assessed by isometric testing and 1 repetition maximum (1RM). Biceps muscle cross sectional area (cm2) was measured by magnetic resonance imaging. Multivariate ANOVA tested if muscle strength and size differed between ACE I/D pre-RT, post-RT, and pre- to post-RT. Because ACE II (n=146) and ID (n=288) did not differ in their RT response, these genotypes were combined and data are reported for ACE II/ID (n=434) versus DD (n=186). RESULTS Pre-RT absolute elbow flexor peak isometric (45.0±0.7 vs 45.4±1.1 kg) and 1RM (9.1±0.1 vs 9.2±0.2 kg) strength and biceps size (17.9±0.2 vs 17.2±0.4 cm2) did not differ between ACE II/ID and DD, respectively. Similarly, post-RT absolute elbow flexor peak isometric (53.6±0.8 vs 52.2±1.3 kg) and 1RM (13.1±0.1 vs 13.2±0.2 kg) strength and biceps size (21.2±0.3 vs 20.6±0.4 cm2) were not different between ACE II/ID and DD (p > 0.05). Absolute (8.6±0.4 vs 6.8±0.6 kg), relative (% of initial values) (22.2±1.0 vs 16.8±1.6 %) and allometric (0.5±0.0 vs 0.4±0.0 kg*kg−0.67) peak elbow flexor isometric strength increases pre- to post-RT were greater for ACE II/ID than DD, respectively (p < 0.01). In contrast, absolute (4.0±0.1 vs 4.0±0.1 kg), relative (51.0±1.5 vs 51.2±2.3 %) and allometric (0.2±0.0 vs 0.2±0.0 kg*kg−0.67) peak elbow flexor strength gains as measured by 1RM; and absolute (3.3±0.1 vs 3.4±0.1 cm2) and relative (18.6±0.5 vs 19.9±0.8 %) muscle size gains were not different between ACE II/ID and DD pre- to post-RT (p > 0.05). CONCLUSION Contrary to our hypothesis, ACE DD gained less peak elbow flexor isometric strength than ACE II/ID genotypes pre- to post-RT, despite similar gains in 1RM and muscle size. Reasons for these differences between the muscle strength response to RT and ACE I/D genotypes are not clear and merit further investigation. Supported by NIH-NINDS R01 NS40606-02