Impact of progressive resistance training on lipids and lipoproteins in adults: A meta-analysis of randomized controlled trials

Abstract

Objective

Given the discrepant findings of progressive resistance training (PRT) on lipids and lipoproteins in adults, we used the meta-analytic approach to examine this issue.

Methods

Randomized controlled trials ≥ 4 weeks dealing with the effects of PRT on lipids and lipoproteins in adult humans ≥ 18 years of age and published between January 1, 1955 and July 12, 2007 were included. Primary outcomes included total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), ratio of total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG). A random-effects model was used for analysis with data reported as means and 95% confidence intervals.

Results

Twenty-nine studies representing 1329 men and women (676 exercise, 653 control) were included. Statistically significant improvements were found for TC (− 5.5 mg/dl, − 9.4 to − 1.6), TC/HDL-C (− 0.5, − 0.9 to − 0.2), non-HDL-C (− 8.7 mg/dl, − 14.1 to − 3.3), LDL-C (− 6.1 mg/dl, − 11.2 to − 1.0) and TG (− 8.1 mg/dl, − 14.5 to − 1.8) but not HDL-C (0.7 mg/dl, − 1.2 to 2.6). Changes were equivalent to − 2.7%, 1.4%, − 11.6%, − 5.6%, − 4.6%, and − 6.4%, respectively, for TC, HDL-C, TC/HDL-C, non-HDL-C, LDL-C, and TG.

Conclusions

Progressive resistance training reduces TC, TC/HDL-C, non-HDL-C, LDL-C and TG in adults.

Introduction

Cardiovascular disease (CVD), the number one cause of mortality in the United States (US), is responsible for more than 600,000 deaths per year (Minino et al., 2006). In addition, 80.7 million adults in the US have CVD (Rosamond et al., 2008). Furthermore, the costs associated with CVD are enormous, with annual total direct and indirect costs estimated to be $287.3 billion in 2008 (Rosamond et al., 2008). One of the major risk factors for CVD is less than optimal lipid and lipoprotein levels, a common problem in the US. For example, it is estimated that more than 80 million adults ages 20 years and older have low-density lipoprotein cholesterol (LDL-C) levels ≥ 130 mg/dl (Rosamond et al., 2008). Exercise, primarily aerobic exercise, is a low-cost therapeutic lifestyle change that has been recommended for improving lipid and lipoprotein levels in adults (Rosamond et al., 2008). While previous meta-analytic research has reported significant improvements in lipids and lipoproteins among both men (Kelley and Kelley, 2006) and women (Kelley et al., 2004) as a result of aerobic exercise, the effects of progressive resistance training (PRT), i.e., weight training, on lipids and lipoproteins in adults have been underwhelming. For example, previous randomized controlled trials addressing the effects of PRT on lipid and lipoprotein outcomes have reported conflicting findings with regards to total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), the ratio of TC to HDL-C (TC/HDL-C), LDL-C and triglycerides (TG) (Blessing et al., 1987, Boardley et al., 2007, Boyden et al., 1993, Bunout et al., 2001, Campbell, 1965, Castaneda et al., 2002, Crowder, 1989, Durak et al., 1990, Elliott et al., 2002, Ensign, 1993, Fahlman et al., 2002, Fenkci et al., 2006, Hagerman et al., 2000, Hersey et al., 1994, Hong, 2004, Johnson et al., 1983, Katznelson et al., 2006, LeMura et al., 2000, Maesta et al., 2007, Manning et al., 1991, Martin, 1994, Olson et al., 2006, Prabhakaran et al., 1999, Sallinen et al., 2007, Sigal et al., 2007, Stone et al., 1982, Thomas et al., 2005, Vincent et al., 2003, Wosornu et al., 1996). Given the conflicting findings regarding the effects of PRT on lipids and lipoproteins in adults, we used the meta-analytic approach (Sacks et al., 1987) to examine the effects of this intervention on lipids and lipoproteins in adults.