Fibrinolytic Responses to Resistance Training in Women

Abstract

During exercise, fibrinolysis increases to protect against exertion-related ischemic events, which are often caused by an occlusive thrombus. No investigation of the fibrinolytic response to resistance training has strictly utilized female participants. This is clinically relevant due to the fact that estrogen, both endogenous and supplemental, has been shown to influence baseline fibrinolytic capacity. Furthermore, fibrinolytic potential is inversely related to body composition. It is unclear if body composition affects the fibrinolytic response to resistance exercise. PURPOSE: The purpose of this study was to assess the fibrinolytic response to resistance training in women, and to assess the effects of body composition on this response. METHODS: Fourteen healthy women (22.6 ± 4 yrs) participated in the study. Subjects were separated into two subsets by body fat as assessed by DEXA: <30% (n=6) and >30% (n=8). Each subject performed 6 sets of 10 leg extension repetitions at an intensity associated with 70% of her measured 1 repetition maximum. The two primary fibrinolytic proteins, tPA and PAI-1, were assessed at baseline, immediately after, and one hour after exercise. Results were analyzed using repeated measures ANOVA. All post-exercise values were corrected for changes in plasma volume. RESULTS: Plasma concentrations of active tPA increased significantly following exercise (p<0.05) and returned to baseline after one hour. Plasma PAI-1 activity did not change following the exercise bout (P<0.05). There was a significant group effect for PAI-1 with the >30% group exhibiting significantly higher plasma concentrations of PAI-1 than the <30% group at all three time points (p<0.05). There were no significant group × time interactions. CONCLUSIONS: Fibrinolytic potential in women increases significantly following a bout of resistance training due to an increase in tPA activity. This cardioprotective response appears to be unrelated to body composition.