Effect of air resistance on the metabolic cost and performance of cycling

Summary

The metabolic cost (VO₂) of cycling against a range of wind velocities (V _W) was studied in a wind tunnel of 15 male cyclists and the results compared with work on a stationary cycle ergometer, uphill cycling on a treadmill, and performance times in road racing competitions.

The results showed that VO₂ at constant treadmill speed was proportional to V ²_W and was a linear function of work rate, both on the stationary ergometer and during uphill cycling on a motor driven treadmill. Maximal values of 5.04 1×min⁻¹ (69.3 ml×kg⁻¹×min⁻¹) and 482 W were observed. The mean force (F) acting on the cyclists during the experiments in the wind tunnel was found to be equal to 0.0175 V ²_W ×ms⁻¹ (r=+0.98). The mean projected area (A _P), drag areas (A _D) and drag coefficient (C _D) for the 15 cyclists were 0.50 m², 0.280 m², and 0.56 m², respectively. During cycling out of doors on a calm day VO₂ was calculated to be a curvilinear function of the cyclists' speed of progression (V). The best guide to the cyclists' maximal aerobic power output (VO_{2 max}) was given by their 16.1 km (10 mile) time:

$$\dot VO_{2\max } (1 \times \min ^{ - 1} ) = - 4.219 + 0.7727{\text{ }}V(ms^{ - 1} )r = + 0.89.$$

The results suggested that the relative aerobic power output (% VO_{2 max}) which could be sustained for a given time by elite cyclists, is similar to that found previously for marathon athletes. However, due to the differences in the non-drag component of the work for given metabolic cost the cyclist will travel approx. 2 1/2 times the distance of an endurance athlete.