Critical power is related to cycling time trial performance

The purpose of this study was to evaluate critical power ((W) over dot(CP)) as an indicator of aerobic fitness in trained cyclists, and to determine i ts relationship to cycling time trial (TT) performance. Thirteen competitiv e USCF category 2 or 3 cyclists provided season's best 40 km TT times (mean [SD]) time = 59.6 min (3.1), and performed two 17 km TT under controlled c onditions (26.6 min [1.1]). Ventilatory threshold (VT) and (V) over dot O(2 )max were determined from a maximal incremental test. (W) over dot(CP) was calculated using the results of four all-out constant power tests. Mean (W) over dot(CP) was 299 (61) W or 4.1 W x kg(-1), VT was 3616 (750) ml x min( -1) or 49.8 ml x kg(-1) x min(-1) (75), and (V) over dotO(2)max was 4596 ml x min(-1) or 63.5 ml x kg(-1) x min(-1) (8.0). (W) over dot(CP) was strong ly related to VT and (V) over dot(2)max, demonstrating that it can serve as a measure of aerobic fitness in this population. Expressions of (W) over d ot(CP) were slightly to considerably more highly related to 17 km and 40 km TT performances (r = -0.77 to -0.91) than were expressions of VT and (V) o ver dot O(2)max (r = -0.71 to -0.87). It is concluded that (W) over dot(CP) provides an aerobic fitness measure for competitive cyclists which can be obtained without invasive testing. In addition, (W) over dot(CP) is strongl y related to the TT performance of competitive cyclists.