Circulo-respiratory responses to different muscular exercises

Summary

Six muscular exercises, i.e., pedalling sitting (PS), cranking sitting (CS), pedalling and cranking (PCC), cranking standing (CST), pedalling reclining (PR), and pedalling with back support (PBS) were compared to see the relationship between work patterns and bodily reactions. Five young males volunteered in the study. CST, CS, PR, PS, and PBS yielded 76, 72, 72, 87, and 97% of$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ (PCC) respectively. Power output in arm work was about 70% of leg work. The ratio of$\dot V_E /\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ in PS and PCC varied only between 22–24, while in CST, CS, PR, and PBS the ventilation equivalent decreased with the severity of exercise. At 40%$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ (CST, CS, PR, and PBS) and 70%$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ (CST, PR, and PS) the heart rates were about 145 beats·min⁻¹ and 155 beats·min⁻¹ respectively. Blood pressure was less in arm work than in leg work. PCC had a compensatory mechanism in lowering systolic blood pressure. At$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ (PBS), the O₂ debt was 8.911, and 3.96 and 6.48 l respectively at 40 and 70%$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ (PBS); next highest values were observed in PR and CS, indicating inclusion of more isometric work component in CS, PR, and PBS. Slow component of the recovery$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ contributed largely to the total O₂ debt. The net mechanical efficiency in most exercises ranged within 14–21%. At 40%$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ the efficiency was high followed by a fall at 70%$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ and again at$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ a marginal improvement in efficiency was noted. Arm and leg work were better performed in upright sitting posture. PCC was beneficial to improve$\dot V_{{\text{O}}_{\text{2}} {\text{max}}}$ and to balance the physiological reactions.