Aerobic exercise, lipids and lipoproteins in overweight and obese adults: a meta-analysis of randomized controlled trials

OBJECTIVE: Use the meta-analytic approach to examine the effects of aerobic exercise on lipids and lipoproteins in overweight and obese adults. DATA SOURCES: (1) Computerized literature searches, (2) cross-referencing from review and original articles, (3) hand searching, and (4) expert review of reference list. STUDY SELECTION: (1) randomized controlled trials, (2) aerobic exercise >= 8 weeks, (3) adult humans >= 18 y of age, (4) all subjects overweight or obese (BMI >= 25 kg/m(2)), ( 5) studies published in journal, dissertation, or master's thesis format, (6) studies published in the English-language, (7) studies published between 1 January 1955 and 1 January 2003, (8) assessment of one or more of the following lipid and/or lipoprotein variables: total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and triglycerides (TG). DATA ABSTRACTION: Dual-coding by the first two authors (inter-rater agreement = 0.96). RESULTS: In total, 13 studies representing 31 groups (17 exercise, 14 control), 613 subjects (348 exercise, 265 control), and up to 17 outcomes were available for pooling. Across all categories, random-effects modeling resulted in statistically significant improvements for TC ((X) over bar +/- s.e.m., -3.4 +/- 1.7 mg/dl, 95% CI, -6.7 to -0.2 mg/dl) and TG ((X) over bar +/- s.e.m., -16.1 +/- 7.3 mg/dl, 95% CI, -30.2 to -2.1 mg/dl) but not HDL ((X) over bar s.e.m., 1.67 +/- 0.8 mg/dl, 95% CI, -0.02 to 3.2 mg/dl) or LDL ((X) over bar +/- s.e.m., -0.5 +/- 1.3 mg/dl, 95% CI, -3.0 to 2.0 mg/dl). Changes were equivalent to improvements of 2% (TC), 11% (TG), 3% (HDL), and 0.3% (LDL). After conducting sensitivity analyses (each study deleted from the model once), only decreases in TG remained statistically significant. Increases in HDL were associated with increases in maximum oxygen consumption (VO2 max in ml/kg/min, r = 0.75, P = 0.002) and decreases in body weight (r = 0.77, P < 0.001), while decreases in LDL were associated with decreases in body weight (r = 0.75, P = 0.009). CONCLUSIONS: Aerobic exercise decreases TG in overweight and obese adults. However, a need exists for additional randomized controlled trials in various overweight and/or obese populations above and beyond those included in our analysis.