Normative values and prediction equations for the modified incremental step test in healthy adults aged 18-83 years

Abstract

Objective: To establish normative values and reference equations for predicting the number of steps and oxygen consumption (VO₂) from the modified incremental step test (MIST) in healthy adults aged 18-83 years.

Design: Prospective observational study.

Participants: One hundred and ninety-four healthy adults aged 18-83 years with normal spirometry.

Settings: Exercise physiology laboratory of a university.

Methods: Participants underwent two MISTs (30 minutes apart). The MIST was performed on a 20-cm-high step using an externally paced rhythm imposed by audible signals, starting with 10 steps per minute and with constant increments of 1 step every 30 seconds.

Main outcomes: Number of steps and VO₂ obtained from MIST.

Results: Normative values were provided for males and females for each age group. The following equations were determined: number of steps = 675.113 + (66.165*sex, 0 female and 1 male) - (5.353*age) - (6.593*body mass index) (R² =0.44, P < 0.001); VO₂ = 0.106 + (0.216*sex, 0 female and 1 male) - (0.008*age [years]) + (0.021*weight [kilograms]) + (0.001*number of steps) (R² =0.80, P < 0.001).

Conclusion: Normative values and prediction equations are proposed for the number of steps and VO₂ which can be used to interpret performance on the MIST in individuals with different health conditions. These equations now need validation in other samples.

Keywords: Exercise test; Oxygen uptake; Physical fitness; Reference values; Step test.