Respiratory gas exchange during treadmill exercise testing: reproducibility and comparison of different exercise protocols

Abstract

Ten subjects performed 4 maximal exercise tests to evaluate reproducibility and effects of treadmill inclination on submaximal and maximal oxygen consumption. They performed a standard Bruce protocol twice, and 1 protocol with progressive speed increase with constant, or without, inclination. At maximal exercise there was no significant difference between the protocols in oxygen consumption, respiratory gas exchange ratio, minute ventilation, plasma lactate, serum potassium or heart rate. Exercise time and treadmill distance were shorter than Bruce protocol with inclination, and considerably prolonged without. Reproducibility for Bruce protocol was good for group comparison of oxygen consumption throughout exercise. The individual variations for oxygen consumption were small at maximal exercise, but were considerable at rest and at the lowest exercise steps, this was slightly improved by analysing longer sampling time. Thus, measurement of oxygen consumption is reliable for group analysis, but interpretation must be careful in individuals unless maximal exercise is obtained. Treadmill inclination may be adjusted according to individual preferences.

Physiological Adaptations to Hypoxic vs. Normoxic Training during Intermittent Living High

“…One week after the posttest the subjects in TR performed an additional VO 2 max test to re-evaluate aerobic capacity following a 7-day return to sea level (~normoxia). The typical error for VO 2 max measurement was 3.4%, which corresponds with, or is favorable to literature data (Nordrehaug et al, 1991; Andersen, 1995; Fielding et al, 1997; Lourenco et al, 2011). …”

Methods to Estimate V˙O2max upon Acute Hypoxia Exposure

“…Finally, hypobaric and normobaric hypoxia had similar effects on the decrease in V O 2max , suggesting that hypoxia, not hypobaria per se, is the predominant environmental factor decreasing V O 2max upon acute exposure to altitude. Importantly, when predictions from group-level models were compared to a dataset of individual participants tested at several altitudes, our best model (nonlinear effects and interactions) had an average error of 3.9 mLIkg j1 Imin j1 , which is similar to measurement error in repeated V O 2max testing (i.e.,~2-4 mLIkg j1 Imin j1 ) (2,27,33,44). This validation is important because it suggests that our predictive models generalize beyond the metadata on which they are based.…”

Applicability of Maximal Oxygen Consumption Criteria in Obese, Postmenopausal Women

“…This is supported by the findings of another study in which VO 2 max, RER, HR, and lactate values were similar between the Bruce protocol and other exercise protocols. 25 Therefore, we believe more women were able to achieve a plateau with the addition of a second test because they were more accustomed to a maximal effort. Besides being older, the women in this study were recruited to be obese and sedentary and, therefore, had a low exercise tolerance.…”