Women with poor physical fitness may have an increased risk of thrombotic events due to increased platelet activation, according to research published in Medicine & Science in Sports & Exercise.
In a study of 62 young women, those with poor cardiorespiratory fitness (CRF) had significantly higher platelet activation than women with average to very good CRF.
However, the study also showed that women with poor CRF were able to achieve normal platelet function by increasing their physical fitness.
The women achieved platelet normalization via endurance training—running for a maximum of 40 minutes—3 times a week over a 2-month period.
“Latently activated platelets release a number of mediators that can encourage the development of atherosclerotic vascular changes,” said study author Stefan Heber, of the Medical University of Vienna in Austria.
“If poor physical fitness is accompanied by a higher level of platelet activation, one can conclude that it also has an influence upon the early stages of this pathogenesis. The training effects we’ve found here are consistent with epidemiological data, according to which fit people have an approximately 40% lower risk of cardiovascular events than those who were physically inactive.”
To uncover their findings, Heber and his colleagues analyzed different aspects of platelet function in healthy, non-smoking women with low CRF, medium CRF, and high CRF.
The team assessed CRF using maximal oxygen consumption (VO2max), which was determined by an incremental treadmill exercise test. VO2max criteria were:
- less than 45 ml/min/kg bodyweight for the low CRF group
- 45 to 55 ml/min/kg bodyweight for the medium CRF group
- more than 55 ml/min/kg bodyweight for the high CRF group.
The researchers assessed platelet activation state and platelet reactivity in these groups of women by evaluating basal and agonist-induced surface expression of CD62P and CD40L, as well as the intraplatelet amount of reactive oxygen species.
The team observed higher basal platelet activation and agonist-induced platelet reactivity in the low CRF group, when compared to the medium and high CRF groups. However, platelet activation and reactivity were roughly the same in the medium and high CRF groups.
For the low CRF group, the researchers assessed platelet function again after the women completed a supervised endurance training program that lasted 2 menstrual cycles. The team found this program was able to normalize platelet function.
