Fibrinolytic Activity at Rest and After Cycle Ergometry and Treadmill Running Performed to Volitional Exhaustion in Male Triathletes

Abstract

Resting fibrinolytic activity (FA) and the fibrinolytic response to cycle ergometry (CE) and treadmill running (TR) performed to volitional exhaustion were evaluated in eight highly trained male triathletes. Fibrinolytic activity of blood was represented as the area of fibrin plate lysis (mm 2). The average (± standard error) resting FA for the triathletes measured before exercise (122 ± 10 mm2) was not significantly different from the FA of plasma obtained from 32 sedentary male subjects (113 ± 8 mm2) at rest. When corrected for exercise-induced hemoconcentration, the absolute increases in FA above resting values were 280 mm2 for CE and 290 mm2 for TR. Cycling produced a 273 percent increase in FA, whereas running caused FA to rise 233 percent above resting levels. As expected, the increases in FA were highly significant for both modes of exercise (p < 0.001). Even though the triathletes achieved significantly higher maximal oxygen uptake values and greater exercise intensities for TR than for CE, exercise-induced changes in FA were not significantly different between the two types of exercise. This suggests that relative work intensity (as a percentage of aerobic capacity) is more important than absolute exercise intensity (oxygen uptake in liters per minute) in terms of producing changes in fibrinolysis. Highly trained male triathletes had a normal resting level of FA and demonstrated relatively large and similar increases in fibrinolysis in response to CE and TR performed to exhaustion. Even if severe physical training were found to reduce the level of resting or post-exercise fibrinolysis, the frequency of activation of the fibrinolytic system by exercise might be effective in the prevention offbrin deposition. The mode of physical activity may not be important in terms of activating fibrinolysis as long as relative work intensity is controlled.