Comparison of oxygen uptake on-kinetic calculations during submaximalexercise

Ross Arena, Reed Humphrey, Mary Ann Peberdy, Michael Madigan

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4 Scopus citations


The mean response time (MRT) and time constant (TC) are two oxygen uptake (VO 2) on-kinetic calculations whose values are presumed to be interchangeable. This study tests the assumption of uniformity among different VO 2 on-kinetic calculations. Nineteen (13 male/6 female) apparently healthy subjects were recruited for this study. Mean age (±SD) for this group was 44.1±10.1 years. Subjects underwent a progressive exercise test and six-minute exercise session (1.6 m/hr, 3.0% grade) on separate days. Both breath-by-breath (bb) and 10-second averaged (avg) ventilatory expired gas data were used to produce four VO 2 on-kinetic calculations (MRT bb, MRT avg, TC bb, TC avg). There were statistically significant differences (p<0.05) between TC bb (17.6 s) and TC avg (22.7 s), MRT bb (22.9 s), and MRT avg (24.7 s). Comparisons amongst TC avg (22.7 s), MRT bb (22.9 s), and MRT avg (24.7 s) did not reach statistical significance (p>0.05). All VO 2 on-kinetic calculations were significantly correlated with peak VO 2, age, and each other. These results indicate that all MRT and TC calculations may not be interchangeable. All VO 2 uptake on-kinetic expressions did, however, appear to represent aerobic capacity and were highly correlated with each other indicating that calculation method may not have an excessively negative impact.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalJournal of Exercise Physiology Online
Issue number2
StatePublished - May 2003


  • Mean Response Time
  • Time Constant
  • Ventilatory Expired Gas


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