The effects of exercise and catecholamines on platelet reactivity or coagulation and fibrinolysis appear to be inconsistent. This may be partly due to the methods employed in previous studies. In the present study, we investigated the effects of acute aerobic exercise and catecholamines on the thrombotic status by a novel in vitro method, shear-induced hemostatic plug formation (hemostatometry), using nonanticoagulated (native) blood. Aerobic exercise (60% maximal O2 consumption) was performed by healthy male volunteers for 20 min, and the effect on platelet reactivity and coagulation was assessed by performing hemostatometry before and immediately after exercise. Exercise significantly increased shear-induced platelet reactivity, coagulation, and catecholamine levels. The effect of catecholamines on platelet reactivity and coagulation was assessed in vitro by adding catecholamines to blood collected in the resting state. The main findings of the present study are that elevation of circulating norepinephrine at levels that are attained during exercise causes platelet hyperreactivity and a platelet-mediated enhanced coagulation. This may be a mechanism of an association of aerobic exercise with thrombotic risk.
While exercise is widely believed to prevent atherothrombotic diseases, it occasionally causes sudden death. This exercise paradox may be due to the inadequate testing of the thrombotic and thrombolytic status. A recently developed shear-induced thrombosis/endogenous fibrinolysis test performed with non-anticoagulated blood samples allows the assessment of the thrombotic state of an individual both at rest and after exercise. This sensitive and physiologically relevant test may help to solve the aforementioned exercise paradox.
A study was conducted to investigate the relationship between sprinting ability and agility using a longitudinal design. The subjects were 70 junior athletes (39 boys and 31 girls) aged 9 to 12 years participating in a Talent Identification and Development program. Physical constitution (height and body weight), 20-m sprint test time, rebound jump index, and ability to change direction (agility test and T-run test) were measured periodically for 3 years. The main results were as follows: 1. Physical constitution, sprinting ability, rebound jump index, and ability to change direction increased significantly along with development in both boys and girls. 2. Performances in the 20-m sprint, agility test, and T-run test in boys were significantly better than in girls, but no significant sex difference was observed in the rebound jump index. 3. Single correlation analysis demonstrated significant correlations between all of the tests. 4. Partial correlation analysis (using age in months as the control variable) revealed significant relationships between the agility test and T-run test in boys and girls, but correlations between 20-m sprint ability and the agility test or T-run test were not significant. 5. There was little difference in the rebound jump index between boys and girls, and it was suggested that ability to change running direction was less affected by simple sprinting or strength-shortening cycle abilities during the developmental period.
Aims] A number of studies have identified abdominal muscle thickness as a significant risk factor for metabolic syndrome (MetS).However, in the absence of longitudinal studies, the causal relationship between abdominal thickness and MetS risk factors has not been elucidated.In this study, we examined the association between abdominal muscle thickness and changes in MetS risk factors.[Methods] We studied 36 patients receiving hospital outpatient care for obesity and MetS.Measurements were taken on two occasions, with an intervening interval of 6 ± 1 months.Data for the following variables associated with the risk of obesity and MetS.Statistical analysis was performed with partial correlation analysis, including age, sex, and current medication, as control variables.[Results] The individual and the combined effects of the control variables were evaluated.However, no significant correlation between abdominal muscle thickness and changes in MetS risk factors was established, after controlling for all combinations of age, sex, and current medication.The abdomen has relatively limited skeletal muscle mass compared to the legs; therefore, variations in muscle mass may have little effect on MetS risk factors.[Conclusions] Although abdominal muscle thickness is a useful indicator for early detection of sarcopenia in obese individuals, our findings suggest that there is a limited association between abdominal wall thickness and MetS risk factors.
