Acute changes in triacylglycerol lipase activity of human adipose tissue during exercise

Although physical exercise is known to increase adipose tissue lipolysis, its effect on the activity of triacylglycerol (TG) lipase, the enzyme regulating TG breakdown, is not known. The aim of the present study was to monitor the acute changes in TG lipase activity of adipose tissue induced during moderate exercise. For this purpose a new assay, sensitive to the phosphorylation state of the enzyme, was developed. Ten young sedentary men cycled for 30 min at a heart rate of 120-130 beats min(-1). Needle adipose tissue biopsy was performed from the buttock area at rest, at 5, 15, and 30 min of exercise, as well as at 15 min of passive recovery. Five other men served as controls by being biopsied as above without exercising. TG lipase activity was determined by measuring the decrease of endogenous TG concentration during incubation of the homogenized tissue. TG lipase activity increased 6.4-fold above baseline at 5 min of exercise (P < 0.001) and fell gradually afterwards, whereas it did not change significantly in the control group. In conclusion, our data show that TG lipase activity in human adipose tissue peaks early during exercise and subsequently decreases despite the maintenance of the physical stimulus.