No abstract

re. Aerobic training improves exercise-induced lipolysis in SCAT and lipid utilization in overweight men. Am J Physiol Endocrinol Metab 285: E984-E990, 2003; 10.1152/ ajpendo.00152.2003.-The aim of this study was to investigate whether endurance training improves lipid mobilization and oxidation in overweight subjects. Eleven young men (25.6 Ϯ 1.4 yr and body mass index 27.7 Ϯ 0.2) performed a 4-mo training program consisting of practicing aerobic exercise 5 days/wk. Before and after the training period, lipid oxidation was explored during a 60-min exercise at 50% of peak O2 consumption by use of indirect calorimetry. Lipid mobilization and antilipolytic ␣2-adrenoceptor effect were also studied using the microdialysis method in abdominal subcutaneous adipose tissue (SCAT). After training, plasma nonesterified fatty acid (NEFA) levels, at rest and during exercise, were significantly lower than before (P Ͻ 0.001). Lipolysis in SCAT was significantly higher after than before training. An antilipolytic ␣2-adrenoceptor effect in SCAT was underlined during exercise before training and disappeared after. The respiratory exchange ratio was lower after training, i.e., the percentage of lipid oxidation was higher only at rest. The amount of lipid oxidized was higher after training, at rest, and during exercise. Although exercise power was higher after training, the relative intensity was equivalent, as suggested by a similar increase in plasma catecholamine concentrations before and after training. In conclusion, 4-mo training in overweight men improved lipid mobilization through a decrease of antilipolytic ␣ 2-adrenoceptor effect in SCAT and lipid oxidation during moderate exercise. Training induced a decrease of blood NEFA, predicting better prevention of obesity. subcutaneous adipose tissue; microdialysis; catecholamines; ␣ 2-adrenoceptor; exercise; lipid oxidation REGULAR EXERCISE ASSOCIATED WITH DIET has been recommended as an important strategy in the prevention and management of obesity. Endurance training appears to be one of the major factors determining the long-term success of weight loss programs (26, 37). One explanation is that exercise partly counteracts the decline in fat oxidation occurring with weight loss during a hypocaloric diet by maintaining adipose lipolytic responsiveness (25, 36).In normal-weight subjects exercise training has been found to result in increased fat oxidation (3), but whole body lipolysis during exercise was not significantly enhanced by training (20).Few studies bear on the effect of exercise on adipose tissue lipolysis in obese subjects, whereas in this population an alteration of catecholamine-stimulated lipolysis has been reported (28,29). In a previous study, we have shown that 3-mo aerobic training in obese men enhanced the lipolytic ␤-adrenergic response of adipose tissue and decreased adipocyte antilipolytic activity of ␣ 2 -adrenoceptors (AR) in vitro (6); moreover, we have shown in vivo that lipolysis at rest was increased during ␤-adrenergic stimulation after physical t...

The aim of the study was to examine whether a moderate exercise increases the utilization of fatty acids during the recovery period in obese men. Six healthy obese participated in a randomized crossover investigation, one with exercise and one without exercise. At 8 a. m., the subjects had a standardized breakfast and they rested in a sitting position for 3 hours. The subjects were maintained in the sitting position for 4 additional hours in one session. In a second session, they exercised for 60 min at 50 % of their VO(2) max and then returned to the sitting position for 3 hours. Respiratory exchange ratio (RER) values were calculated by indirect calorimetry. During the resting session, plasma non-esterified fatty acids (NEFA) and glycerol concentrations rose progressively, whereas RER progressively decreased. During the exercise, plasma catecholamines, NEFA, glycerol, growth hormone and cortisol levels and RER increased while insulin decreased. During the recovery, plasma NEFA increased and glycerol decreased. During the first hour of recovery, RER values were lower and fatty acid utilization higher than during the same period of the resting session. The study shows that exercise induces modifications in hormonal factors promoting lipid mobilization and suggests that exercise provide substantial amounts of NEFA for muscle oxidation during recovery from an exercise bout in obese subjects.

No abstract