Validation of a Modified Submaximal Balke Protocol to Assess Cardiorespiratory Fitness in Individuals at High Risk of or With Chronic Health Conditions—A Pilot Study

Objectives: This study aims to validate a submaximal treadmill walking test for estimation of maximal oxygen consumption (VO(2max)) in individuals at high risk of or with chronic health conditions. Method: Eighteen participants (age 62 ± 16 years; VO(2max) 31.2 ± 5.9 ml kg(−1) min(−1)) at high risk of getting or with established chronic diseases performed two valid modified Balke treadmill walking protocols, one submaximal protocol, and one maximal protocol. Test duration, heart rate (HR), and rate of perceived exertion (RPE) were measured during both tests. VO(2max) was measured during the maximal test. VO(2max) was estimated from the submaximal test by multiple regression using time to RPE ≥ 17, gender, age, and body mass as independent variables. Model fit was reported as explained variance (R(2)) and standard error of the estimate (SEE). Results: The model fit for estimation of VO(2max) from time to RPE ≥ 17 at the submaximal test, body mass, age, and gender was R(2) = 0.78 (SEE = 3.1 ml kg(−1) min(−1), p ≤ 0.001). Including heart rate measurement did not improve the model fit. Conclusions: The submaximal walking test is feasible and valid for assessing cardiorespiratory fitness in individuals with high risk of or chronic health conditions.