Power Output Demands of Womenʼs Road Cycling Time Trial

Abstract

Over the past 20 years the power output produced during many different types of cycling competition have been described (eg., cyclocross, mountain bike, track sprint, men's road and women's road). Little, if any, information is available describing the power output profiles of nationally competitive female road cyclists during the time trial. PUPPOSE: To document the cycling power output produced by nationally competitive female road cyclists during a 20-km time trial (∼30min) and to compare this power output with the maximum mean power output produced during a laboratory based 30-minute time trial (MMP30min) and the power output corresponding to VO2max (MAP). METHODS: On two successive years (Y1 and Y2) members of the Australian National Women's Road Cycling team (Y1 n=8, 25±4y, 168±4 cm, 59±3 kg, 321±20 WMAP, 63±3 ml.kg-1.min-1 VO2pk; Y2 n=6, 23±4y, 166±3 cm, 59±3 kg, 313 W MAP, 62±2, ml.kg-1·min-1 VO2pk) participated in a maximum graded exercise test (125W; inc. 25 W every 3min) and on the subsequent day a maximum 30-min laboratory time trial using a Lode electromagnetically braked cycle ergometer. Within 4 wks cyclists competed in the National Championship time trial event (∼27 km, ∼40 min) using a time trial bike fitted with a dynamically calibrated instrumented crank (SRM, 4 sg model). Power output, velocity and cadence data were sampled at 1 hz. For both years the time-trial was raced on a relatively flat course. A paired t-test was used to compare differences in power output produced in the lab and the field. RESULTS: On both years the monitored cyclist achieved top 10 results at the National Championships. The average laboratory MMP30min was similar for both years (Y1 – 265±22 W, 4.5±.4 W.kg-1; Y2 – 259±15 W, 4.3±.2 W.kg-1), a power output corresponding to 82±4% and 80±3% of the MAP. Compared to the laboratory MMP30min the average time trial power output in the field was ∼10–15W lower (Y1 – 254±15 W, p=.02; Y2 – 250±13 W, p=.01) and demonstrated greater variability. The average power output during the time trial in the field was within 3 W of the power output associated with the onset of blood lactate as calculated using the Dmax technique (Y1 – 256±25 W; Y2 – 253±21 W). CONCLUSIONS: These data are the first to document the power output produced by nationally competitive female road cyclists during a 27-km time trial in the field (>260 W or 4.5 W.kg-1 for ∼40 minutes). In the field power output tends to be lower than in the lab (approximately Dmax power) and more variable possibly due to the slightly longer effort (∼8–1 0min) and forced reductions in power output during sharp cornering in the field.