Negative accumulated oxygen deficit during heavy and very heavy intensity cycle ergometry in humans

Ozyener, F., Rossiter, H.B., Ward, S. and Whipp, B.J. (2003) Negative accumulated oxygen deficit during heavy and very heavy intensity cycle ergometry in humans. European Journal of Applied Physiology, 90, pp. 185-190. (doi: 10.1007/s00421-003-0870-y)

Abstract

The concept of the accumulated O2 deficit (AOD) assumes that the O2 deficit increases monotonically with increasing work rate (WR), to plateau at the maximum AOD, and is based on linear extrapolation of the relationship between measured steady-state oxygen uptake (V̇O2) and WR for moderate exercise. However, for high WRs, the measured V̇O2 increases above that expected from such linear extrapolation, reflecting the superimposition of a "slow component" on the fundamental V̇O2 mono-exponential kinetics. We were therefore interested in determining the effect of the V̇O2 slow component on the computed AOD. Ten subjects [31 (12) years] performed square-wave cycle ergometry of moderate (40%, 60%, 80% and 90% θˆL ), heavy (40%Δ), very heavy (80%Δ) and severe (110% V̇O2 peak) intensities for 10–15 min, where θˆL is the estimated lactate threshold and Δ is the WR difference between θˆL and V̇O2 peak. V̇O2 was determined breath-by-breath. Projected "steady-state" V̇O2 values were determined from sub- θˆL tests. The measured V̇O2 exceeded the projected value after ~3 min for both heavy and very heavy intensity exercise. This led to the AOD actually becoming negative. Thus, for heavy exercise, while the AOD was positive [0.63 (0.41) l] at 5 min, it was negative by 10 min [−0.61 (1.05) l], and more so by 15 min [−1.70 (1.64) l]. For the very heavy WRs, the AOD was [0.42 (0.67) l] by 5 min and reached −2.68 (2.09) l at exhaustion. For severe exercise, however, the AOD at exhaustion was positive in each case: +1.69 (0.39) l. We therefore conclude that the assumptions underlying the computation of the AOD are invalid for heavy and very heavy cycle ergometry (at least). Physiological inferences, such as the "anaerobic work capacity", are therefore prone to misinterpretation.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: UNSPECIFIED
• Authors: Ozyener, F., Rossiter, H.B., Ward, S., and Whipp, B.J.
• College/School: College of Medical Veterinary and Life Sciences
• Journal Name: European Journal of Applied Physiology
• ISSN: 1439-6319
• ISSN (Online): 1439-6327