Reproducibility in simulated 40 km time trial cycling and its associated metabolic stress

Abstract

This study examined the reproducibility of a simulated 40 km time trial (40TT) repeated on 3 separate occasions prior to pre‐season training. On days 1 (TT1), 3 (TT2) and 5 (TT3), 9 experienced cyclists (X± SD VO2max: 4.27 ± 0.28 L · min−1) performed the 40TT using their own bicycles mounted on wind‐loaded rollers which were mechanically connected to an odometer to record distance cycled. Exercise time and selected metabolic and respiratory measures were recorded at 10 km intervals. The results showed that the mean VO2 (3.57 ±0.50, 3.61 ±0.38, 3.59±0.38L· min−1), cycling velocity (557.4±42.7, 568.3±46.1, 579.8±36.7 m·min−1) and time (min: s; 72:00 ± 5 :20, 70: 50 ± 5:16, 69: 57 ± 4:49) were not different (p < 0.05) between TT1, TT2, TT3, respectively. However, coefficient of variation for time was 3.7%. 40TT cycling intensity was performed at 7% above ventilation threshold of each individual. BLa (mM) was different at only the 10 km interval between TT1 (6.2 ±1.98) vs. TT2 (4.3 ±1.41) and TT3 (4.5 ± 1.63), suggesting that the subjects began TT1 at a higher intensity but were not able to maintain the pace. The intra‐class coefficient ranged between 0.36 and 0.91 for selected variables. The poorest relationship for each was between TT1 vs. TT2 and TT1 vs. TT3. These results suggest that a simulated 40TT adequately assessed the metabolic stress of the cyclists, but that the first attempt was not a valid measure of each subject's performance ability. A learning trial seems important even when assessing experienced, competitive cyclists, prior to pre‐season training.