Reference values for the 6-min walk test in healthy middle-aged and older adults: from the total distance traveled to physiological responses

Valores de referência para o teste de caminhada de 6 minutos em adultos saudáveis de meia-idade e idosos: da distância total percorrida às respostas fisiológicas

Valores de referencia para la prueba de caminata de 6 minutos en adultos sanos de mediana edad y de edad avanzada: de la distancia total a las respuestas fisiológicas

Abstract

Introduction:

Physiological responses to the 6-min walk test (6MWT) have been increasingly evaluated in patients with cardiopulmonary diseases. However, previous studies did not include healthy persons.

Objective:

To evaluate the intensity of 6MWT, to develop a series of predictive equations for the physiological variables and to test their reliability in healthy middle-aged and older adults.

Method:

We evaluated 102 non-trained healthy adults (54 women, aged 61 ± 10 years) and a cross-validation sample of 30 participants. We measured physiological responses to the 6MWT and a cardiopulmonary exercise testing (CPET) on a treadmill.

Results:

The R² values for regression analysis adjusted by age, body mass, stature, and sex ranged from 0.25 for heart rate and 0.46 for peak $\dot{V}{\mathrm{O}}_2$ The 6MWT distance and 6MWT peak $\dot{V}{\mathrm{O}}_2$ represented 110 ± 10% and 102 ± 15% of the predicted values, respectively, using our equations. The intensity of 6MWT corresponded to 72 ± 13% of the peak O₂ and 78 ± 23% of the peak HR in the CPET. Peak $\dot{V}{\mathrm{O}}_2$ in the CPET was adequately predicted by 6MWT peak $\dot{V}{\mathrm{O}}_2$ (R² = 0.76) and 6MWD (R² = 0.54).

Conclusion:

The 6MWT represents a moderate to high-intensity test in middle-aged and older healthy adults and is valid for assessing maximal aerobic exercise capacity. Physiological responses to the 6MWT may be adequately predicted with a combination of anthropometrics and demographics.

Keywords:
Walking; Reference Values; Exercise