Abstract

OBJECTIVE:

To investigate how exercise training and detraining affect oxidized low-density lipoprotein (Ox-LDL)-potentiated platelet function in men.

DESIGN:

Cohort study.

SETTING:

Department of physical medicine and rehabilitation.

PARTICIPANTS:

Ten sedentary men (mean age +/- standard error of the mean, 21.6+/-0.2 y) who did not engage in any regular physical activity for at least 1 year before the study.

INTERVENTIONS:

Subjects cycled on an ergometer at about 50% of maximal oxygen consumption for 30 minutes daily, 5 days a week, for 8 weeks, then detrained for 12 weeks.

MAIN OUTCOME MEASURES:

During the experimental period, blood samples from the subjects were collected before and immediately after a progressive exercise test (ie, strenuous, acute exercise) every 4 weeks. The following measurements were taken when the subjects were at rest and immediately after exercise: plasma lipid profile, plasma Ox-LDL level, and platelet aggregation and intracellular calcium concentration ([Ca2+]i) elevation induced by adenosine disphosphate (ADP) alone or simultaneous ADP and Ox-LDL addition.

RESULTS:

Analytical results indicated that: (1) plasma total cholesterol and LDL levels were reduced after exercise training from 151+/-7 mg/dL and 58+/-2 mg/dL to 133+/-6 mg/dL and 46+/-2 mg/dL (P<.05), respectively, whereas the plasma Ox-LDL level remained unchanged; (2) platelet aggregation and [Ca2+]i elevation promoted by 100 microg/mL of Ox-LDL were significantly increased from 70%+/-5% and 91%+/-7% of resting level to 108%+/-4% and 125%+/-3% after strenuous, acute exercise (P<.05); (3) exercise training decreased resting and postexercise 100 microg/mL Ox-LDL-potentiated platelet aggregation (ie, 31%+/-4% and 82%+/-4%, respectively; P<.05) and [Ca2+]i elevation (ie, 35%+/-6% and 71%+/-4%, respectively; P<.05); (4) detraining reversed the training effects on lipid profile and platelet function; and (5) treating the platelet with L-arginine-inhibited Ox-LDL-potentiated platelet activation during the experimental period.

CONCLUSIONS:

Our results suggest that 8 weeks of exercise training decreased the plasma LDL level, but failed to influence production of plasma Ox-LDL. Importantly, resting and exercise-induced Ox-LDL-potentiated platelet activation was decreased by exercise training. However, this was reversed by detraining to the pretraining level.