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.
ABSTRACT
The purpose of this study was to determine the effects of L-carnitinesupplementation on carbohydrate [CHO] and fat metabolism after resistance exercise. In this investigation, using a double blind, randomized, crossover, repeated measure design [1 wk washout], 10 healthy resistance-trained men [Mean +/- SD: age, 24.03 +/- 2.00 yr; mass, 72.26 +/- 5.31 kg; height, 173.90 +/- 5.02 cm] consumed 2 g placebo or LC supplement daily for one week and then performed 6 exercises of a resistance exercise protocol. Each workout was performed for 3 sets of 12 repetitions with 55% 1RM and rest periods were kept to 60 s between all sets and workout. Expired gases were measured for calculating CHO and fat oxidation. Venous blood samples were obtained before and after supplementation, immediately after resistance exercise and after the 1[st] and 24[th] hour after resistance exercise. Samples were analyzed for markers of glucose, NEFA, glycerol and insulin. Also L-carnitine plasma concentrations were measured, before and after supplementation. The results of this study suggest that plasma carnitine concentrations increased 14% [p 0.05]. Increased plasma insulin concentrations with L-carnitine and placebo after resistance exercise attenuated result in attenuate fat oxidation in this study