Effects of exercise training and detraining on oxidized low-density lipoprotein-potentiated platelet function in men

Wang J-S, Chow S-E. Effects of exercise training and detraining on oxidized low-density lipoprotein-potentiated platelet function in men. Arch Phys Med Rehabil 2004;85:1531-7. 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±0.2y) 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±7mg/dL and 58±2mg/dL to 133±6mg/dL and 46±2mg/dL (P<.05), respectively, whereas the plasma Ox-LDL level remained unchanged; (2) platelet aggregation and [Ca ²⁺]_i elevation promoted by 100μg/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 100μg/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.