Measurement Properties of the Modified Incremental Step Test for Assessing Exercise Capacity in Individuals With Type
Larissa Barbosa de Carvalho1, Renata Cruzeiro Ribas2, Maria Clara Noman de Alencar3
1Graduate Program in Rehabilitation Sciences and Physical-Functional Performance, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
Background And Purpose:
A reduction in exercise capacity (EC) can be observed in individuals with type 2 diabetes (T2D) on cardiopulmonary exercise test (CPET). However, CPET is a costly maximal exercise test, limiting its routine use. This study aimed to analyze the criterion validity, convergent validity, and test-retest reliability of the Modified Incremental Step Test (MIST), a simple, inexpensive, and portable submaximal exercise test, for assessing EC in individuals with T2D.
Methods:
Fifty individuals with T2D (56.9 ± 11.4 years old, 50% male) attended two visits within a 2- to 10-day interval. On the first visit, participants underwent a CPET. On the second visit, two repetitions of the submaximal exercise tests, the MIST and the 6-minute walk test (6MWT), were conducted in a random order. Criterion validity was assessed using the Pearson correlation coefficient between the number of steps climbed in the best-performed MIST and peak oxygen consumption (peak VO2) from CPET. Convergent validity was evaluated by the Pearson correlation coefficient between the best MIST performance and the distance covered in the best 6MWT. Test-retest reliability was determined using the intraclass correlation coefficient (ICC) between two MIST repetitions.
Results:
Convergent validity was supported by a moderate correlation between the number of steps climbed in the best-performed MIST and the distance covered in the best 6MWT (r = 0.65; p < 0.001; n = 50). In contrast, criterion validity (r = 0.53; p = 0.023; n = 18) and test-retest reliability (ICC [95% CI] = 0.64 [0.44-0.78]) did not meet the criteria for adequate measurement properties.
Discussion:
This multicenter methodological study, conducted in accordance with COSMIN recommendations, contributes to the literature by evaluating the psychometric properties of the MIST for assessing EC in individuals with T2D. Although the findings do not support the MIST as a substitute for CPET, its convergent validity may support its use when 6MWT execution is not possible.
