4-meter gait speed test as a tool to prescribe walking exercise intensity in individuals with COPD

Introduction Exercise training remains the essential component of rehabilitation programs in individuals with chronic obstructive pulmonary disease (COPD)1. In order to guarantee the training benefits, an appropriate prescription of exercise intensity is necessary1. The target intensity for training is generally prescribed as a percentage of maximum exercise capacity1; however, a simple field test such as the 6-minute walking test (6MWT) was shown to be useful in exercise prescription for walking2-4 . The importance of the 6MWT to evaluate exercise capacity is undeniable5; nevertheless, the test requires space and time, which may hinder its use in home visits and in some clinical settings. On the other hand, the 4-meter gait speed (4MGS) is a reliable test, which requires short time and space6-9. It reflects global well-being and captures the multisystemic effects of disease severity9. Furthermore, walking is the main activity in a rehabilitation program and gait speed measure is modifiable through rehabilitation, therefore being a potential marker of functional improvement or decline8-9. Although the 4MGS has potential as an assessment tool, further work is necessary to confirm its utilization for exercise prescription. Therefore, the aims of this study were to verify whether it is possible to prescribe the intensity of walking exercise training and to predict the distance covered in the 6MWT through the 4MGS in individuals with moderate-to-very severe COPD. In addition, since there are different available protocols for the 4MGS, another aim was to identify which protocol better estimates these outcomes.