The effects of graded resistance exercise on platelet aggregation and activation

Purpose: The purpose of this study was to examine the effects of resistance exercise with varying intensity but with similar volume on platelet aggregation and activation. Methods: Thirteen healthy male subjects randomly completed three resistance exercise test trials at an intensity corresponding to 40%, 60%, and 80% of one repetition maximum (1-RM) in which the subjects performed six exercises including upper- and lower-body parts. Venous blood samples were obtained before and immediately after each exercise trial and analyzed for platelet count (PLT), plateletcrit (PCT). mean platelet volume (MPV), platelet aggregation, and beta-thromboglobulin (B-TG). Plasma volume changes were estimated from hemoglobin and hematocrit readings before and after each exercise trial. Results: Although all exercise trials were followed by a significant (P < 0.05) increase in PLT (thrombocytosis), PCT, and MPV, this rise was not related to the exercise intensity (P > 0.05). Exercise was also followed by a significant increase (P < 0.05) in platelet aggregation, but this only occurred with the high but not with the low concentrations of adenosine diphosphate (ADP). Although ANOVA showed a significant overall increase (P < 0.05) in the concentration of B-TG after exercise, this rise only reached the assigned level of significance (P < 0.05) after 80% exercise trial. Conclusion: It was concluded therefore that resistance exercise is followed by an increase in PLT, PCT, and MPV, and this occurred in parallel with an in vivo activation of platelet as manifested by an increase in platelet aggregation and a rise in B-TG.