Abstract
BackgroundGenetics plays a role in determining potential for athletic ability (AA) and sports performance (SP). In this study, AA involves comparing sedentary controls with competitive athletes in power and endurance activities as well as a mix between the two (SP). However, variable results from genetic association studies warrant a meta-analysis to obtain more precise estimates of the association between PPARGC1A Gly482Ser polymorphism and AA/SP.MethodsMulti-database literature search yielded 14 articles (16 studies) for inclusion. Pooled odds ratios (ORs) and 95% confidence intervals (CI) were used to estimate associations. Summary effects were modified based on statistical power. Subgroup analysis was based on SP (power, endurance and mixed) and race (Caucasians and Asians). Heterogeneity was assessed with the I2 metric and its sources examined with outlier analysis which dichotomized our findings into pre- (PRO) and post-outlier (PSO).ResultsGly allele effects significantly favoring AA/SP (OR > 1.0, P < 0.05) form the core of our findings in: (i) homogeneous overall effect at the post-modified, PSO level (OR 1.13, 95% CI 1.03–1.25, P = 0.01, I2 = 0%); (ii) initially homogeneous power SP (ORs 1.22–1.25, 95% CI 1.05–1.44, P = 0.003–0.008, I2 = 0%) which precluded outlier treatment; (iii) PRO Caucasian outcomes (ORs 1.29–1.32, 95% CI 1.12–1.54, P = 0.0005) over that of Asians with a pooled null effect (OR 0.99, 95% CI 0.72–1.99, P = 0.53–0.92) and (iv) homogeneous all > 80% (ORs 1.19–1.38, 95% CI 1.05–1.66, P = 0.0007–0.007, I2 = 0%) on account of high statistical power (both study-specific and combined). In contrast, none of the Ser allele effects significantly favored AA/SP and no Ser-Gly genotype outcome favored AA/SP. The core significant outcomes were robust and showed no evidence of publication bias.ConclusionMeta-analytical applications in this study generated evidence that show association between the Gly allele and AA/SP. These were observed in the overall, Caucasians and statistically powered comparisons which exhibited consistent significance, stability, robustness, precision and lack of bias. Our central findings rest on association of the Gly allele with endurance and power, differentially favoring the latter over the former.
Highlights
Athletic ability (AA) determines sports performance (SP)
Gly allele effects significantly favoring AA/SP (OR > 1.0, P < 0.05) form the core of our findings in: (i) homogeneous overall effect at the post-modified, PSO level; (ii) initially homogeneous power SP (ORs 1.22–1.25, 95% confidence intervals (CI) 1.05–1.44, P = 0.003–0.008, I2 = 0%) which precluded outlier treatment; (iii) PRO Caucasian outcomes (ORs 1.29–1.32, 95% CI 1.12–1.54, P = 0.0005) over that of Asians with a pooled null effect and (iv) homogeneous all > 80% (ORs 1.19–1.38, 95% CI 1.05–1.66, P = 0.0007–0.007, I2 = 0%) on account of high statistical power
F, Fixed-effects; Fs, Favoring SP; Gly, Glycine; GS, Gain in significance; HWE, Hardy-Weinberg Equilibrium; I2, Measure of variability expressed in %; K, number designation of the article; Log odds ratios (ORs), Logarithm of standardized OR; Maf, Minor allele frequency; M-H, Mantel-Haenszel; n, Number of studies; OR, Odds ratio; P, P-value; Pa, P-value for association; Pb, P-value for heterogeneity; PPARGC1A, Peroxisome proliferator-activated receptor gamma co-activator-1-alpha; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; PRO, Pre-outlier; PSO, Postoutlier; R, Random-effects; RH, Reduced heterogeneity; RNS, Retained non-significance; RS, Retained significance; SE, Standard error; Ser, Serine; SP, Sports performance
Summary
Athletic ability (AA) determines sports performance (SP). SP is a highly polygenic and complex phenotype as well as having a multifactorial etiology where genetic and environmental factors contribute to differences among trained athletes [1]. The mix represents a continuum of SP activities between power and endurance Explosive activities such as sprint and weightlifting characterize strength/power while endurance involves sustained activities such as marathons and cycling. Muscle fiber composition in these two types of athletes differs where activation of types II and I fibers occur during high-intensity activity in power and endurance performances, respectively [3, 4]. These contrasts stem from diverging genetic backgrounds of power and endurance athletes that drive their physiology into different trajectories [5]
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