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

PAVLOU, KONSTANTIN N., WILLIAM P. STEFFEE, ROBERT H. LERMAN, and BELTON A. BURROWS. Effects of dieting and exercise on lean body mass, oxygen uptake, and strength. Med. Sci. Sports Exerc., Vol. 17, No. 4, pp. 466-471, 1985. The effects of exercise on lean body mass (LBM), fat mass (FM), maximal oxygen uptake (V̇O2max), and quadriceps (QD) strength were studied in 72 male, mildly obese ( x̄=38% fat) subjects ( x̄ age, 43.5 yr) randomly assigned to one of eight treatments arranged in a 2 x 4 factorial plan with exercise (EX) and non-exercise (NE) and four diets as the two 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 weight, V̇O2max using the Wilmore- Costill method, and QD strength with the Cybex II system. Weight loss of the combined EX (11.8 ± 0.6 kg) (x̄ ± 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 weight 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 V̇O2max from 2.9 ± 0.3 to 3.4 ± 0.2 1· min-1 (P<0.001), whereas the NE group was unchanged (3.0 ± 0.3 to 2.9 ± 0.4 l·min-1 (NS)). QD strength increased in the EX group from 172 ± 7.0 to 210 + 6.6 Nm( P< 0.001) whereas no change was found in the NE group values (NS). We conclude that the addition of EX to a calorie-deficient dietary regimen results in (1) preservation of existing LBM; (2) increase in V̇O2max (3) increase in strength; (4) increase in fat utilization for energy production; and (5) more effective reduction in fat stores than diet alone.