[ effects of circuit resistance exercise on fat and carbohydrate metabolism during endurance exercise in overweight men]

ABSTRACT

This study examined the effects of circuit resistance exercise on fat and carbohydrate metabolism during endurance exercise in overweight men. Ten overweight men [mean +/- SD age, 28.8 +/- 4.8 yr; BMI, 28.2 +/- 1.4 kg/m2; vo2max, 23.3 +/- 3.7 ml/kg/min] performed two types of exercise regimens 1] Endurance exercise [E], and 2] Circuit resistance exercise, followed by endurance exercise [RE]. Circuit resistance exercise consisted of six stations, each with three circuits at 50% of 1-RM [one repetition maximum], and a total exercise time of 21 min. Endurance exercise consisted cycle ergometer exercise at 60% of the maximal oxygen uptake for 30 min. Expired gases at rest, before and during endurance exercise were measured for calculating fat and carbohydrate oxidation. Venous blood samples were taken at rest, before and immediately after endurance exercise. Blood samples were analyzed for glucose, nonestrified fatty acids [NEFA], malonyl COA [MCOA], glycerol and insulin. Plasma glycerol concentrations during endurance exercise increased 53% in RE vs. 46% in the E group [P<0.001]. Concentration of plasma glucose before endurance exercise was higher in RE than in the E group [P<0.001]. In RE exercise, although fat oxidation through the 30-min endurance exercise [mean value] was greater than in the E regimen, there was no significant difference between the two groups [P>0.05]. Also, no significant difference was observed in the NEFA, MCOA, insulin, carbohydrate oxidation responses [P>0.05]. Lipolysis during the submaximal exercise is enhanced by prior circuit resistance exercise in overweight men.