Sassi Aldo, Rampinini Ermanno, Morelli Andrea, Impellizzeri Franco M.

For submaximal steady state workloads leading to exhaustion between one and some decades of minutes, some authors (Sassi et al., 1999; Sassi et al, submitted) suggested to estimate the time to exhaustion (TEEST) using a regression equation which includes lactate parameters collected at min 5 and 10 of a submaximal constant workload, with a root mean square error in cross validation of 13.2 %. The aim of this study was to use this approach to estimate the individual power – time to exhaustion (W-TEEST) in cyclists of different performance level. The resulting W-TEEST relationships were compared with the actual mechanical power output data recorded during their training. Data were collected in 3 professional cyclists (PC), 2 mountain bikers (MB), and 3 recreational cyclists (RC) (VO2max 69.2  15.4 ml•kg-1•min-1; weight 69.5  11.0 kg; height 179  9 cm; age 33  9 yrs; body fat 6,0±4,9). The individual W-TEEST relationship was estimated submitting each subject to 2 or 3 submaximal workload (5 min at 100 watt, followed by increases of 25 watt•30 sec-1 until the target workload, that was maintained for 10 min). Workloads were selected in order to obtain for each subject 2 TEEST between 10 min and 60 min. Competitive cyclists performed the tests during the competitive period. The W-TEEST relationships were obtained fitting the individual TEEST according to the logarithmic equation: W = b • ln(TE) + a. The data of the subjects were also compared with their training power output. All parameters were normalized for lean body mass (LBW). The maximal aerobic power (MAP, i.e. the maximal power that can be sustained for about 60 min) extrapolated by the W-TEEST equations (MAPEST), was highly correlated with the subject’s VO2max•kgLBW-1 (r = 0.95; p<0.001). The average value of b was -0.716±0.180, and its correlation with VO2max•kgLBW-1 was r = 0.67. Cyclists approached their W-TEEST regression line only during fractions of high intensity training sessions, and in few occasions 3 of them overcame by 10-20 W the W-TEEST during uphill cycling. The high correlation found between VO2max•kgLBW-1 and MAPEST supports the usefulness of the W-TEEST method to evaluate cyclists’ endurance capacity. The moderate correlation between b and Vo2maxLBW, means that the decay of the W vs TE is only partially related to the VO2max of the subjects (r2=0.45). The individual degree between MAP and the anaerobic threshold (i.e. the maximal power that can be sustained for one hour) underlines the need to individualize the power output training prescription. The W-TEEST relationship of the PC were in agreement with the ones presented in literature concerning workout lasting 30-60 min (Lucia et al., 2001). In conclusion, this W-TEEST approach could have practical usefulness both for endurance capacity evaluation and for submaximal training power output prescription for cyclists. Further more systematic validations are required.