Purpose: The aim of this study was to examine the association of exercise frequency (ExFreq) and volume (total weight lifted by military press and squats (SQ)) with change in body composition among postmenopausal women participating in a progressive resistance training study.
Methods: Previously, sedentary women (n = 122, age = 56.3 ± 4.3 yr) were followed for 6 yr. At 6 yr, there were women who had been randomly assigned to resistance training at baseline (n = 65) controls that were permitted to cross over to the exercise program at 1 yr (n = 32) and 25 true controls. Exercisers and crossovers directed to perform eight core exercises for two sets of eight repetitions at 70%-80% of one-repetition maximum, three times weekly, plus progressive weight bearing, stretching, and balance. Body weight and fat were measured at baseline and annually using anthropometry and dual-energy x-ray absorptiometry.
Results: Average change in body weight and total body fat were 0.83 ± 5.39 and 0.64 ± 4.95 kg at 6 yr, respectively. In multiple linear regression, ExFreq, military press, and SQ were significantly inversely associated with change in body weight (standardized beta coefficient (SBC) = −0.22 to −0.28, P < 0.01), fat (SBC = −0.25 to −0.33, P < 0.01), and trunk fat (SBC = −0.20 to −0.31, P < 0.03) after adjusting for age, years on hormone therapy, change in lean soft tissue, baseline body composition, and baseline habitual exercise. The lowest tertile of SQ (equivalent to 2.5% attendance) demonstrated significant gain in weight, fat, and trunk fat over 6 yr (P < 0.004), whereas the highest tertile SQ (equivalent to 64% attendance) was able to maintain their weight, total, and regional fat.
Conclusions: We conclude that resistance training is a viable long-term method to prevent weight gain and deleterious changes in body composition in postmenopausal women.
1Arizona Cancer Center, University of Arizona, Tucson, AZ; 2Department of Physiology, University of Arizona, Tucson, AZ; and 3Department of Nutrition, University of Arizona, Tucson, AZ
Address for correspondence: Jennifer W. Bea, Ph.D., Arizona Cancer Center, 1515 N. Campbell Ave., PO Box 245024, Tucson, AZ 85724-5024; E-mail: firstname.lastname@example.org.
Submitted for publication June 2009.
Accepted for publication November 2009.