Effects of time of day and acute resistance exercise on platelet activation and function
Issue title: Selected Proceedings of the 15th Conference of the European Society for Clinical Hemorheology and Microcirculation (ESCHM), June 28–July 1, 2009, Pontresina, Switzerland
Affiliations: Department of Sport and Exercise Physiology, Faculty of Sport Sciences, Shahid Beheshti University G.C., Tehran, Iran | Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
Note: [] Corresponding author: Dr. Sajad Ahmadizad, Department of Sport and Exercise Physiology, Faculty of Sport Sciences, University of Shahid Beheshti, Velenjak Square, Evin, Tehran, Iran, Postcode: 1983963113; Tel.: +0098 21 29902931; Fax: +0098 21 22431953; E-mail: s_ahmadizad@sbu.ac.ir
Abstract: The present study was designed to ascertain the interaction between time of day and resistance exercise on platelet activation and function. Ten healthy male subjects (age, 29.3 ± 4.5 yr) undertook identical bouts of resistance exercise on two separate occasions. Tests were randomised and performed at two different time of day (08:00 and 20:00 h). Subjects performed 3 sets of 7 repetitions of six exercises at 80% of 1RM, which was followed by 30 min recovery. Beta-thromboglobulin (B-TG) and platelet indices were measured at rest, post-exercise and at the completion of recovery. Platelet aggregation was determined in platelet rich plasma using collagen and three different concentrations of adenosine-5′-diphosphate. Platelet aggregations induced by different aggregating agents at rest were significantly higher in the morning (p < 0.05). Although platelet aggregations induced by collagen and ADP did not change in response to resistance exercise, significant differences between the results in the morning and evening trials were observed (p < 0.01). These differences emulated the differences observed at rest. A significant (P < 0.05) increase in B-TG was found following exercise with no difference between morning and evening trials. It was concluded that resistance exercise induces significant changes in platelet activation, irrespective of time of day, as assessed by beta-thromboglobulin.
Keywords: Acute resistance exercise, time of day, platelet aggregation, B-TG, platelet indices
