Stroke volume response to progressive exercise in athletes engaged in different types of training

Summary

Using the impedance cardiography method, heart rate (ϕ _c) matched changes on indexed stroke volume (SI) and cardiac output (CI) were compared in subjects engaged in different types of training. The subjects consisted of untrained controls (C), volleyball players (VB) who spent about half of their training time (360 min · week⁻¹) doing anaerobic conditioning exercises and who had a maximal oxygen uptake ($\dot VO_{2\max }$) 41% higher than the controls, and distance runners (D) who spent all their training time (366 min·week⁻¹) doing aerobic conditioning exercises and who had a$\dot VO_{2\max }$ 26% higher than VB. The subjects performed progressive submaximal cycle ergometer exercise (10 W·min⁻¹) up toϕ _c of 150 beats·min⁻¹. In group C, SI had increased significantly (P<0.05) atϕ _c of 90 beats·min⁻¹ ( + 32%) and maintained this difference up to 110 beats·min⁻¹, only to return to resting values on reaching 130 beats·min⁻¹ with no further changes. In group VB, SI peaked (+ 54%) atϕ _c of 110 beats·min⁻¹, reaching a value significantly higher than that of group C, but decreased progressively to 22010 of the resting value on reaching 150 beats·min⁻¹. In group D, SI peaked atϕ _c of 130 beats·min⁻¹ (+ 54%), reaching a value significantly higher than that of group VB, and showed no significant reduction with respect to this peak value on reaching 150 beats·min⁻¹. As a consequence, the mean CI increase perϕ _c unit was progressively higher in VB than in C (+46%) and in D than in VB (+ 105%). It was concluded that thef _c value at which SI ceased to increase during incremental exercise was closely related to the endurance component in the training programme.