Influence of the process used to determine the line of economy in pedalling when calculating the maximum deficit in accumulated oxygen
To assess the effect on the maximal oxygen deficit (MOD) of the intensity, the duration and the number of bouts utilized to calculate the submaximal VO2/intensity relationship, six males were tested on eight separate days. After familiarization, an incremental exercise test was used to assess the VO2peak an another three tests were performed to obtain the submaximal VO2/intensity relationship at the following intensities: 80, 100, 110, 120, 130, 140, 150, 160, 180, 200 and another time 100 w. Four different linear regressions were calculated: R1, R2, R3 and R4. R1, R2 and R4 were calculated from the VO2/intensity relationship between 80 and 130 w (R1, n=5), 140 y 200 w (R2, n=5) and 80 y 200 w (R4, n=10). The VO2 for each submaximal bout was taken as the mean for the last two min (i.e., the 5th and 6th min). Subsequently, R3 was obtained from the VO2/intensity relationship between 80 and 200 w (R3, n=4) during an incremental exercise test to exhaustion with 40 w steps every 3 min, using the mean VO2 reached at the third min. Lastly, the maximal oxygen deficit (MOD) was calculated for a 45-s Wingate test.
There were no significant differences between R4 and R3. However, the pendents and the intercepts were not correlated. The pendents were 15% lower for R1 than for R2 (9.591 ± 1.236 y 11.261 ± 0.878 ml.min-1, respectively, p<0.05), while the intercepts were higher for R1 than for R2 (709.216 ± 154.808 y 510.583 ± 114.204 ml.min-1, respectively, p<0.05). Between R1 and R2, neither the pendents nor the intercepts were correlated. The MOD calculated from R2 was 18% higher than that obtained from R1 (p=0.06). The Pearson correlation coefficient between the MOD values derived from R3 and R4 was not significant (r=0.76, p=0.08). Conversely, a close correlation was found between MOD obtained from R2 and R4 (r=0.99, p<0.001). This study shows that the MOD shows a high variability dependent on the procedure utilized to calculate the VO2/intensity relationship.
KEY WORDS: Exercice, cycling economy, efficiency, reliability, oxygen deficit.