Measurement Properties of the Modified Incremental Step Test for Assessing Exercise Capacity in Individuals With Type...

Area of Science:

• Exercise physiology
• Clinical assessment
• Diabetes management

Background:

• Individuals with type 2 diabetes (T2D) often exhibit reduced exercise capacity (EC).
• Cardiopulmonary exercise testing (CPET) is a gold standard for EC assessment but is costly and resource-intensive.
• There is a need for accessible and reliable methods to evaluate EC in T2D.

Purpose of the Study:

• To evaluate the criterion validity, convergent validity, and test-retest reliability of the Modified Incremental Step Test (MIST) for assessing EC in individuals with T2D.
• To determine if MIST can serve as a practical alternative to CPET.

Main Methods:

• Fifty individuals with T2D underwent CPET and two repetitions of MIST and 6-minute walk test (6MWT) on separate visits.
• Criterion validity was assessed by correlating MIST performance with CPET-derived peak oxygen consumption (peak VO2).
• Convergent validity was evaluated by correlating MIST performance with 6MWT distance. Test-retest reliability was assessed using intraclass correlation coefficient (ICC).

Main Results:

• MIST demonstrated moderate convergent validity with 6MWT (r=0.65, p<0.001).
• Criterion validity between MIST and CPET (r=0.53, p=0.023) and test-retest reliability (ICC=0.64) did not meet adequate measurement property criteria.
• The study included 50 participants aged 56.9 ± 11.4 years, with 50% males.

Conclusions:

• The MIST is not a suitable substitute for CPET in assessing EC in individuals with T2D.
• While MIST shows some convergent validity with 6MWT, its psychometric properties do not fully support its widespread clinical adoption.
• MIST may be considered when 6MWT is not feasible, but further validation is warranted.