Table 2.

Assessment of heterogeneity among reports of the association between physical activity and global DNA methylation

SubgroupEstimates (n)SMD (95% CI); PI2Meta-regression P
Study demographics
 Mean age
  <504−0.10 (−0.51–0.31); P = 0.5084.9%0.25
  50–<6060.37 (−0.04–0.78); P = 0.0888.4%
  60+40.21 (−0.15–0.57); = 0.2587.2%
 % Female
  <6050.36 (0.02–0.70); P = 0.0486.1%0.07
  60+70.00 (−0.12–0.12); P = 0.9924.6%
 Country
  North American80.26 (−0.03–0.55); P = 0.0885.9%0.73
  Other60.09 (−0.28–0.46); P = 0.6487.4%
Physical activity measure
 Study design
  Intervention60.25 (−0.27–0.77); P = 0.3492.2%0.66
  Observational80.12 (−0.06–0.31); P = 0.1973.4%
 Measurement type
  Self-reported60.16 (−0.07–0.39); P = 0.1780.7%0.99
  Othera80.19 (−0.21–0.59); P = 0.3489.4%
 Duration of physical activityb
  Long-term100.29 (0.04–0.54); P = 0.0287.8%0.11
  Acute4−0.12 (−0.59–0.36); P = 0.6383.7%
DNA methylation assessment
 Genomic context
  Global2−0.09 (−0.29–0.12); P = 0.420.00%0.61
  Repetitive elements90.25 (0.00–0.49); P = 0.04885.4%
  LUMA30.15 (−0.84–1.14); P = 0.7794.2%
 Assay type
  Non-LUMA110.18 (−0.02–0.39); P = 0.0882.9%0.92
  LUMA30.15 (−0.84–1.14); P = 0.7794.2%
 Tissue
  Blood130.25 (0.05–0.45); P = 0.0284.2%0.01
  Muscle1−0.90 (−1.38 to −0.42); P < 0.01
  • aOther includes intervention studies and observational studies with objective assessments via accelerometry.

  • bLong-term physical activity exposure was defined as a physical activity intervention that lasted 6 or more months in duration or an observational study employing self-reported physical activity levels reflective of typical levels in the past year. Acute physical activity exposure was defined as a physical activity intervention lasting less than 6 months or an observational study that assessed levels of physical activity over periods shorter than 2 months using objective measures.