THE Y-INTERCEPT OF THE MAXIMAL WORK-DURATION REGRESSION AND FIELD-TESTS OF ANAEROBIC CAPACITY IN CYCLISTS

The purpose of the present study was to provide initial data upon whic h field tests of anaerobic capacity for cyclists might be developed, b y examining the relationships between the y-intercept of the maximal w ork-duration regression (Y-int) and cycle performance variables in fif teen well-trained male cyclists (mass = 73.3 +/- 8.6 kg; VO2 peak = 4. 93 +/- 0.70 l . min(-1)). The Y-int was determined from three maximal supra-VO(2)peak cycle bouts varying in duration from 195 to 369 s. Eac h cyclist performed two performance tests: 1) an all-out cycle sprint over 1000 m (AOS) during which the accumulated time over intervals of 125 m (e.g., AOS125, AOS250, etc. was recorded: 2) a 2-by-2000 m ride from which an ''anaerobic distance'' (An(l)) was determined as the pro duct of anaerobic speed (i.e. average speed during a second, maximal 2 000 m time-trial minus the average speed during a 20 km time-trial) an d time taken to complete the maximal 2000 m ride. The frontal area (FA ) of each cyclist and common values for air density, work efficiency a nd the drag coefficient were used to estimate the energy equivalent of An(l). The Y-int was 20.0 +/- 9.4 kJ or 278 +/- 128 J . kg(-1). The Y -int (J . FA(-1)) was correlated (p less than or equal to 0.05) with A OS250 (r = - 0.50), AOS375 (r = -0.53) and AOS625 (r = - 0.50) which w ere 21.5 +/- 1.1 s, 30.1 +/- 1.3 s and 47.5 +/- 1.9 s long, respective ly. The Y-int (kJ) was also correlated with AOS375 (r = - 0.51), but Y -int (kJ) was not correlated with a performance variable lasting longe r than similar to 30 s. The energy equivalent of An(l) (91.5 +/- 26.0 kJ) was similar to the energy equivalent for Y-int (90.9 +/- 43 kJ), a lthough these two variables were not significantly correlated. However , given the potential sources of variance in determining both of these variables, their quantitative similarity provides limited evidence su pporting the use of An(l) to estimate anaerobic capacity. The results also support the use of an all-out sprint performance lasting between 20 -30 s to best reflect anaerobic work capacity in cyclists.