ANAEROBIC CONTRIBUTION TO THE TIME TO EXHAUSTION AT THE MINIMAL EXERCISE INTENSITY AT WHICH MAXIMAL OXYGEN-UPTAKE OCCURS IN ELITE CYCLISTS,KAYAKISTS AND SWIMMERS

Using 23 elite male athletes (8 cyclists, 7 kayakists, and 8 swimmers) , the contribution of the anaerobic energy system to the time to exhau stion (t(lim)) at the minimal exercise intensity (speed or power) at w hich maximal oxygen uptake ((V) over dotO(2max)) occurs (I(V) over dot O(2max)) was assessed by analysing the relationship between the t(lim) and the accumulated oxygen deficit (AOD). After 10-min warming up at 60% of (V) over dotO(2max), the exercise intensity was increased so th at each subject reached his I-(V over dotO2max) in 30 s and then conti nued at that level until he was exhausted. Pre-tests included a contin uous incremental test with 2 min steps for determining the I-(V over d otO2max) and a series of 5-min submaximal intensities to collect the d ata that would allow the estimation of the energy expenditure at I-(V over dot O2max). The AOD for the t(lim), exercise was calculated as th e difference between the above estimation and the accumulated oxygen u ptake. The mean percentage value of energy expenditure covered by anae robic metabolism was 15.2 [(SD 6)%, range 8.9-24.1] with significant d ifferences between swimmers and kayakists (16.8% vs 11.5%, P less than or equal to 0.05) and cyclists and kayakists (16.4% vs 11.5%, P less than or equal to 0.05). Absolute AOD values ranged from 26.4 ml . kg(- 1) to 83.6 ml . kg(-1) with a mean value of 45.9 (SD 18) ml . kg(-1). Considering all the subjects, the t(lim) was found to have a positive and significant correlation with AOD (r = 0.62, P less than or equal t o 0.05), and a negative and significant correlation with (V) over dotO (2max) (r = -0.46, P less than or equal to 0.05). The data would sugge st that the contribution of anaerobic processes during exercise perfor med at I(V) over dotO(2max) should not be ignored when t(lim) is used as a supplementary parameter to evaluate specific adaptation of athlet es.