Sassi A1, Morelli A1, Impellizzeri FM1, Ruffini G1,  Mognoni P2

1, Service Mapei, Castellanza, Varese, Italy; 2, CNR-ITBA, Milano, Italy

The exercise time to exhaustion (TE) during submaximal exercise has been used to evaluate endurance athletes. The variability in repeated TE measurements is high (McLellan et al. 1995) but, on the contrary, the ability to complete a target work bout in a minimal amount of time, that is in some way a similar variable, has a coefficient variation of only 1 % (Hickey et al. 1992). However, the high variability in TE may be accepted if changes of TE are large in different periods of the agonistic season. The acceptance of repeated TE measurements may be low but TE could be predicted before its reaching. The TE was measured in 11 subjects (age 25+7.5 yrs, height 179.5+7.3 cm, body mass 71.1+6.4kg, VO2max 66.6+13.0 ml-min-l-kg-1) during submaximal cycling at various steady state energy expenditures corresponding to 82.6+8.9% of VO2max. A negative and significant (p=0.02) Spearman rank correlation was found between TE (29.3+26.4 min) and the % of VO2max. The end tidal PCO2, the ventilation and capillary blood lactate concentration were strictly related and change linearly with time. The logarithms of their rates of change were strongly related to the logarithms of TE (p<0.001). In a second group of 8 professional cyclists (age 27.4+3.5 yrs, height 181.6+6.3 cm, body mass 75.2+7.2 kg, VO2max 77.6+4.9 ml-min-l-kg-1 ) the same previous variables were measured at a mechanical power corresponding to 5.3 W-kg-1 of body mass, the target time being 15 min. The physiological variables were also used to predict TE. The measurements were repeated three times: at the beginning of December (before the beginning of the winter training), at the end of the winter training period and during the first two weeks of the competition season. A non-parametric analysis of variance for repeated measurements showed a significant difference between the first and third experimental sessions. The sensitivity of the different kind of measures was similar. In conclusion simple respiratory variables may be assessed during heavy but submaximal exercise before the occurrence of exhaustion to evaluate the training conditions in endurance athletes. The statistical relationship between these variables and the races success it’s worthwhile to be evaluated.

Book of Abstract ECSS Rome, 04-0110