The incidence of VO2 plateau at VO2 max in a cardiac-diseased population

We sought to determine the incidence of V̇O ₂ plateau at V̇O ₂max in a cardiovascular-diseased (CVD) population using 4 different sampling intervals (15-breath moving average, 15 s, 30 s, and 60 s) and 3 different V̇O ₂ plateau criteria (≤50 mL·min ^-1, ≤80 mL·min^-1, and ≤150 mL·min ^-1). A total of 69 people (62±10 yrs.) with recently diagnosed CVD performed a maximal exercise test (10:07±2:24 min) on a treadmill. The test was classified as maximal (n=57, 2 430±605 mL·min ^-1) if self-terminated due to fatigue or classified as symptom-limited (n=12, 1 683±438 mL·min^-1) if symptoms presented. Chi-square analysis revealed a significant (p<0.05) effect of sampling interval on incidence of V̇O ₂ plateau at V̇O ₂max across all 3 V̇O ₂ plateau criteria. The sampling interval had an increasingly stronger influence on the incidence of V̇O ₂ plateau at V̇O ₂max with smaller criterion thresholds as evidenced by the Cramer's V statistics: [≤50 mL·min ^-1 (Cramer's V=0.548, p<0.05], ≤80 mL·min^-1 [Cramer's V=0.489, p<0.05], ≤150 mL·min^-1 [Cramer's V=0.214, p<0.05]. Incidence of V̇O₂ plateau at V̇O ₂max in CVD individuals is significantly influenced by the sampling interval applied. Based on our findings we recommend a15 breath moving average and V̇O ₂ plateau criterion of ≤50 mL·min^-1.