Effect of strenuous arm crank exercise on platelet function in patients with spinal cord injury

Objective: To investigate the effects of arm crank exercise on various platelet functions and prostacyclin in individuals with spinal cord injury (SCI). Design: Case-control study. Setting: Research project at a hospital-based exercise physiology laboratory. Participants: Seven men (with lesions at levels T11, n = 1; T12, n = 2; L1, n = 2; L2, n = 2) and 3 women (T12, n = 1; L1, n = 2) in the SCI group had SCI for at least 6 weeks. Ten age- and gender-matched healthy people who had not engaged in any regular physical activity for at least 1 year were selected as the control group. Intervention: All subjects exercised strenuously by using an arm crank engometer. Main Outcome Measure: Platelet adhesiveness on fibrinogen-coated surface and epinephrine-induced aggregation in vitro, plasma soluble P-selectin (sP-selectin), and urinary 6-keto-prostaglandin F-1alpha (6-keto PGF(1alpha)) levels. Results: The SCI group had higher platelet adhesiveness and aggregability and plasma sP-selectin level, but lower urinary 6-keto PGF(1alpha) level than the control group. Platelet adhesiveness and aggregability were enhanced by strenuous arm exercise in all subjects, but only in the SCI group was sP-selectin level increased by exercise. Strenuous exercise raised the levels of 6-keto PGF(1alpha) in control group subjects, but not in subjects with SCI. Conclusions: Individuals with SCI had more extensive basal and exercise-induced platelet activation and sP-selectin release than people without SCI. Moreover, strenuous arm exercise, which enhanced the release of prostacyclin in healthy subjects, failed to do so in those with SCI.