Field-measured drag area is a key correlate of level cycling time trial performance

Abstract

Drag area (A d) is a primary factor determining aerodynamic resistance during level cycling and is therefore a key determinant of level time trial performance. However, A d has traditionally been difficult to measure. Our purpose was to determine the value of adding field-measured A d as a correlate of level cycling time trial performance. In the field, 19 male cyclists performed a level (22.1 km) time trial. Separately, field-determined A d and rolling resistance were calculated for subjects along with projected frontal area assessed directly (AP) and indirectly (Est A P). Also, a graded exercise test was performed to determine VO 2 peak, lactate threshold (LT), and economy. VO 2 peak (l min -1) and power at LT were significantly correlated to power measured during the time trial (r = 0.83 and 0.69, respectively) but were not significantly correlated to performance time (r = -0.42 and-0.45). The correlation with performance time improved significantly (p < 0.05) when these variables were normalized to A d. Of note, A d alone was better correlated to performance time (r = 0.85, p < 0.001) than any combination of non-normalized physiological measure. The best correlate with performance time was field-measured power output during the time trial normalized to A d (r = -0.92). A P only accounted for 54% of the variability in A d. Accordingly, the correlation to performance time was significantly lower using power normalized to A P (r = -0.75) or Est A P (r = -0.71). In conclusion, unless normalized to A d, level time trial performance in the field was not highly correlated to common laboratory measures. Furthermore, our field-measured A d is easy to determine and was the single best predictor of level time trial performance.