Influence of training on markers of platelet activation in response to a bout of heavy resistance exercise.

Recent connections between platelet activity and cardiovascular disease have raised questions of whether platelet function varies in exercising individuals. Resistance training has been linked to a possible reduction in hyper-aggregability of platelets, especially following acute strenuous exercise. The present investigation was designed to explore the effects of an acute resistance exercise test on the primary hemostatic system in both resistance-trained (RT) and untrained (UT) individuals. Ten RT (five men and five women; age, 26.0 ± 4.5 years; height, 175.12 ± 8.54 cm; weight, 79.56 ± 13.56 kg) and ten UT (five men and five women; age, 26.4 ± 6.2 years; height, 170.31 ± 7.45 cm; weight 67.88 ± 16.90 kg) individuals performed an Acute Exhaustive Resistance Exercise Test (AERET; six sets of ten repetitions of squats at 80 % of the 1-Repetition Maximum (RM)). Blood samples were obtained before, immediately after, and at 15, 60, and 120 min following the AERET. Blood samples were analyzed for platelet count, von Willebrand factor antigen (vWF:Ag), beta-thromboglobulin (β-TG), and platelet factor 4 (PF4). B-TG showed significant differences (p < 0.05) between RT and UT at +15 and +60 min. Both groups showed a main effect for time in platelet count, vWF, and β-TG following the AERET, whereas PF4 remained unchanged. All blood variables returned to baseline 120 min after exercise. Compared with UT, RT demonstrated reduced platelet activation in response to an acute bout of heavy resistance exercise. Reduced platelet activation may be attributed to training status, as shown by a reduction in plasma concentrations of B-TG in the RT group.