Calcineurin Gene Variation and Resistance Exercise Training Responses in MERET

Abstract

1830 Calcineurin has been reported to play an important role in skeletal muscle differentiation and hypertrophy. We identified a novel 5 base pair insertion deletion (I/D) in the promoter of the calcineurin gene that corresponds to a kxd binding site. PURPOSE: We investigated whether the gene variant was associated to the physiological responses observed in the Molecular Epidemiology of Resistance Exercise Training (M.E.R.E.T.) study. METHODS: We hypothesized that this variation would be associated to body composition and strength changes in 136 young adult men and women who participated in 10 weeks, 3 hrs/week of resistance exercise training at 80% of one repetition maximum (1RM). RESULTS: Results are presented as marginal means ± standard error. Percent lean mass gain was significantly higher in the II genotype group (II = 3.0 ± 0.3%, n = 104; ID = 1.9 ± 0.5%, n = 32, p0.05) No differences were observed in the relative gain in arm (II = 3.9 ± 0.4%, ID = 4.8 ± 0.6%, p>0.05) and leg (II = 1.2 ± 0.4%, ID = 1.5 ± 0.6%, P>0.05) circumference between genotype groups. Change in biceps + triceps 1RM was also similar between groups (II = 15 ± 1 kg, ID = 15 ± 2 kg, P>0.05). Change in quadriceps + hamstring 1RM was greater in the ID genotype group (II = 40 ± 2 kg, ID = 48 ± 4 kg, P0.05) No differences were observed in the gain in arm (II = 0.9 ± 0.1 kg/cm2, ID = 1.0 ± 0.1, p>0.05) and leg (II = 1.5 ± 0.1 kg/cm2, ID = 1.8 ± 0.1, p>0.05) muscle quality (mass/strength) between genotype groups (P>0.05). Percent gain in bone area (BMC/BMD) was significantly higher in the II genotype group (II = 1.5 ± 0.3%, n = 45; ID = 0.1 ± 0.5%, n = 16; P<0.05). CONCLUSIONS: These results suggest that the calcineurin promoter kxd I/D genotype affects some body composition and strength responses to RET.