A Simple Method to Quantify the V-O 2 Mean Response Time of Ramp-Incremental Exercise

Danilo Iannetta, Juan M. Murias*, Daniel A. Keir

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)

Abstract

During ramp-incremental exercise, the mean response time (MRT) of oxygen uptake (V-O 2 ) represents the time delay for changes in muscle V-O 2 to be reflected at the level of the mouth and is generally calculated by linear (MRT LIN ) and monoexponential (τ′) fitting of V-O 2 data. However, these methods yield MRT values that are highly variable from test-to-test. Purpose Therefore, we examined the validity and the reproducibility of a novel method to calculate the MRT. Methods: On two occasions, 12 healthy men (age, 30 ± 10 yr; V-O 2max : 4.14 ± 0.47 L·min -1 , 53.5 ± 7.3 mL·kg -1 ·min -1 ) performed a ramp-incremental cycling test (30 W·min -1 ) that was preceded by a step transition to 100 W. The ramp power output corresponding to the steady-state V-O 2 at 100 W was determined and the difference between that power output and 100 W was converted to time to quantify the MRT (MRT SS ). Results: The values of MRT LIN , τ′, and MRT SS were 28 ± 16 s, 27 ± 12 s, and 26 ± 11 s, respectively, which were not different (P > 0.05) from each other. However, compared to the MRT parameters derived from the fitting-based methods, MRT SS had a higher correlation coefficient (R = 0.87) and a smaller coefficient of variation (15% ± 9%) from test-to-test. Conclusions: In conclusion, the novel method proposed in the current study was found to be valid and highly reproducible in a test-retest design. Therefore, we advocate the use of this approach when a precise and accurate determination of the MRT is needed to properly align the V-O 2 data with power output during ramp-incremental exercise.

Original languageEnglish
Pages (from-to)1080-1086
Number of pages7
JournalMedicine and Science in Sports and Exercise
Volume51
Issue number5
DOIs
Publication statusPublished - 1 May 2019
Externally publishedYes

Keywords

  • MRT
  • RAMP EXERCISE
  • V-O KINETICS

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