Effects of dieting and exercise on lean body mass, oxygen uptake, and strength

Abstract

The effects of exercise on lean body mass (LBM), fat mass (FM), maximal O2 uptake .ovrhdot.VO2 max and quadriceps (QD) strength were studied in 72 male, mildly obese (.hivin.X [mean] = 38% fat) subjects (.hivin.X age, 43.5 yr) randomly assigned to 1 of 8 treatments arranged in a 2 .times. 4 factorial plan with exercise (EX) and non-exercise (NE) and 4 diets as the 2 factors. Exercise consisted of a 3 d/wk, 8-wk aerobics program (70-85% maximum heart rate) accompanied by a calisthenics program. LBM was determined by whole body potassium (40K), FM by subtracting LBM from total body wt, .ovrhdot.VO2 max using the Wilmore-Costill method, and QD strength with the Cybex II system. Weight loss of the combined EX (11.8 .+-. 0.6 kg) (.hivin.X .+-. SE) and NE (9.2 .+-. 0.3 kg) groups was not statistically different. LBM of the EX group was unchanged (from 63.1 .+-. 1.9 to 62.5 .+-. 2.1 kg), whereas in the NE group it was reduced from 62.6 .+-. 1.1.to 59.3 .+-. 1.2 kg (P < 0.001) accounting for 36% of total wt loss. FM loss was greater for the EX group (11.2 .+-. 1.5 kg) when compared to the NE (5.2 .+-. 1.6 kg) group (P < 0.001). The EX group exhibited an increase in .ovrhdot.VO2 max from 2.9 .+-. 0.3 to 3.4 .+-. 0.2 l .cntdot. min-1 (P < 0.001), whereas the NE group was unchanged (3.0 .+-. 0.3 to 2.9 .+-. 0.4 l .cntdot. min-1 (NS [not significant]). QD strength increased in the EX group from 172 .+-. 7.0 to 210 .+-. 6.6 N .cntdot. m (P < 0.001) whereas no change was found in the NE group values (NS). The addition of EX to a calorie-deficient dietary regimen results in preservation of existing LBM, increase .ovrhdot.VO2 max: increase in strength; increase in fat utilzation for energy production and more effective reduction in fat stores than diet alone.