Fig 1.
Summary flowchart of literature search.
PPARGC1A: Peroxisome proliferator-activated receptor gamma co-activator-1-alpha; SP: sports performance; HWE: Hardy-Weinberg Equilibrium.
Table 1.
Characteristics of the included studies that examined the association of PPARGC1A Gly482Ser polymorphism with sports performance.
Table 2.
Outlier and modified effects for Gly allele associations with sports performance.
Fig 2.
Forest plot outcome of PPARGC1A Gly allele effects on SP power in the pre-modifier analysis.
Diamond denotes the pooled odds ratio (OR). Squares indicate the OR in each study, with square sizes directly proportional to the weight contribution (%) of each study. Horizontal lines represent 95% confidence intervals (CI). The Z test for overall effect indicates significance (P = 0.003). The χ2 test shows absence of heterogeneity (P = 0.66, I2 = 0%). LEGEND: M-H: Mantel-Haenszel; I2: measure of variability expressed in %.
Fig 3.
Forest plot outcome of PPARGC1A Gly allele effects on SP endurance in the PRO analysis.
Diamond denotes the pooled odds ratio (OR). Squares indicate the OR in each study, with square sizes directly proportional to the weight contribution (%) of each study. Horizontal lines represent 95% confidence intervals (CI). The Z test for overall effect indicates significance (P = 0.03). The χ 2 test shows presence of heterogeneity (P = 0.0005, I2 = 68%). LEGEND: M-H: Mantel-Haenszel; I2: measure of variability expressed in %; CID, confidence interval difference.
Fig 4.
Galbraith plot analysis of Gly allele effects on SP in endurance identifying the sources of heterogeneity.
The three studies that lie above and below the +2 and—2 confidence limits are the outliers. LEGEND: Log OR: logarithm of standardized odds ratio; SE: standard error.
Fig 5.
Forest plot outcome of outlier treatment on PPARGC1A Gly allele effects on SP endurance in the PSO analysis.
Diamond denotes the pooled odds ratio (OR). Squares indicate the OR in each study, with square sizes directly proportional to the weight contribution (%) of each study. Horizontal lines represent 95% confidence intervals (CI). The Z test for overall effect indicates high significance given (P = 0.003). The χ 2 test indicates non-heterogeneity (P = 0.10, I2 = 41%). LEGEND: M-H: Mantel-Haenszel; I2: measure of variability expressed in %; CID, confidence interval difference.
Table 3.
Sensitivity analysis of Gly allele comparisons with significant outcomes favoring sports performance.
Table 4.
Publication bias assessment of Gly allele comparisons with significant outcomes favoring sports performance.