"Tailored" step test for a rapid, accurate and safe VO2max determination in healthy elderly

“Tailored” step test for rapid, accurate and safe VO2max determination in healthy elderly. Ceciclia Bellotti, Lorenzo Casiello, Silvia Pogliaghi Faculty of Kinesiology, University of Verona, Italy PURPOSE: The study aimed at developing and validating a “tailored” version of the Åstrand step test, suitable for VO2max determination in healthy elderly. Furthermore, we tested the hypothesis that a direct measure (compared to estimation) of the step test VO2, adds accuracy to VO2max determination in this population, characterized by low fitness and muscle strength and reduced coordiantive ability. METHODS: In 27 healthy elderly (age 68+5, 14 ♂, 13 ♀) a target VO2 (tVO2) for the step test was calculated as 60% of the VO2max (predicted based on their referred activity pattern). Thereafter, subjects performed a 5-min test, on a 30 cm step, with a stepping rate (10-25 steps*min-1) “tailored” based on tVO2 and the predicted cost of stepping. Heart rate (HR) and VO2 were measured using a portable, hand-held, metabolic analyzer. VO2max was estimated based on Åstrand equation and age correction using either tVO2 (t-estVO2max) or measured VO2 (m estVO2max). Finally, VO2max was measured directly (dVO2max) during an incremental cycling test to exhaustion with breath by breath determination of cardiorespiratory variables, with a traditional metabolic chart. Agreement among t estVO2max, m estVO2max and dVO2max was evaluated by Bland Altman analysis. RESULTS: All the subjects completed the incremental exercise to exhaustion (maximal HR 98±7% of age-predicted value, maximal respiratory quotient 1.1±0.04). Mean ± standard deviation dVO2max was 27±5 ml*kg-1*min-1. All the subjects were also able to complete the “tailored” step test with no difficulty. m estVO2max was not significantly different from dVO2max (bias -0.3, not different from 0; precision 4.1 ml*kg-1*min-1). On the contrary, t-estVO2max was significantly underestimated compared to dVO2max (bias -2.3, ≠ 0; precision 4.6 ml*kg-1*min-1). CONCLUSION: The study developed and validated a “tailored” version of the Åstrand step test, suitable for a rapid (5 min duration), safe (submaximal test) and accurate (unbiased) VO2max determination in healthy elderly individuals. In this population, estimation of the step test VO2 leads to a small (9%) yet significant error in VO2max estimation. Therefore, our data suggest that a direct measure of the step test VO2 should be performed to assure accuracy to VO2max.estimation. The study was supported by Cosmed, Italy