Effect of sampling on variability and plateau in oxygen uptake

Abstract

To evaluate the effect of the gas exchange sampling interval on variability and plateau in O2 uptake (VO2), 10 subjects underwent steady-state treadmill exercise at 50% maximal VO2 and 6 subjects underwent maximal testing using a ramp protocol. During steady-state exercise, gas exchange data were acquired by using 10 different sampling intervals. The variability in VO2 was greater as the sampling interval shortened (SD = 4.5 ml.kg-1.min-1 for breath-by-breath vs. 0.8 ml.kg-1.min-1 for 60-s samples). The breath-by-breath data suggested a Gaussian distribution, and most of the variability was attributable to tidal volume (51%). During ramp testing, the slope of the change in VO2 (for each sample) was regressed with time. Considerable variability in the slopes was observed throughout exercise, and in each subject the slopes varied about zero, demonstrating both positive and negative values throughout submaximal effort. These observations were made despite the use of large sampling intervals. Shortening the sample resulted in even greater variability. We conclude that 1) the sampling interval can have a major impact on gas exchange data during exercise and 2) considerable variability exists in the slope of the change in VO2 with a consistent change in external work regardless of the sample used, suggesting that a plateau (defined as the slope of a VO2 sample at peak exercise that does not differ significantly from a slope of zero) in VO2 is not a reliable physiological marker for maximal effort.

Comparison of Maximal Oxygen Uptake and Anaerobic Threshold in Soccer and Handball Players

“…During the incremental testing period, heart rate (HR) was monitored continuously using a wireless HR monitor (Polar RS800 SD, Finland) and was synchronized to ventilatory signals. Breath-by-breath VO 2 was smoothed using a five-step average filter, and then reduced to 15 s stationary averages (Data Management Software, Cosmed, Rome, Italy) to reduce the noise so as to enhance the underlying characteristics [23].…”

Optimizing the exercise test for pharmacological investigations.

“…Our laboratory recently noted that in the same patients, a plateau may or may not occur depending on the application of different criteria. 54 Additionally, the sampling interval used has a pronounced effect on the occurrence of a plateau, and the observation of a plateau may vary from day to day. This may explain the fact that a plateau has been reported to occur in between 7% and 75% of individuals tested.54,55 Despite its wide application for over 30 years, the plateau remains an inconsistent and somewhat tenuous concept.…”

Influence of Resistance Training Variables on Excess Postexercise Oxygen Consumption: A Systematic Review

“…Additionally it is difficult to recognize how untrained individuals could perform without intervals 21 consecutive sets of different exercises without compromising the work volume, even though the workload of 50-55% 1RM may be considered as moderate. Finally the strategy to �t the mask on the subject during the last set of a given station, in order to allow the VO 2 values to be stable before the postexercise assessment, may have biased the results since the used apparatus frequently requires longer time to stabilization, particularly in intermittent exercises [37].…”