Six-minute walk test: a tool for predicting maximal aerobic power (VO₂  max) in healthy adults

The 6-min walk test (6MWT) is cost-effective and well-documented field test for assessing functional exercise capacity and response to medical interventions in diverse patient groups, and predicting cardiorespiratory fitness among healthy people.

Assessments of cardiorespiratory fitness in terms of maximal aerobic power (VO₂ max) have great potential in public health monitoring to predict future health, early retirement and ability to independent living. This study aimed to develop a prediction model for VO₂ max based on 6MWT results among healthy adults.

The study comprised of pilot and validation studies. In validation study, seventy-five 19- to 75-year-old adults (39 men, 36 women) were equipped with portable gas analyser and heart rate monitor. Participants performed 6MWT on a 15-m indoor track and maximal graded exercise test (GXT) on a treadmill. We evaluated performance of the developed prediction model among 1583 Finnish adults.

Participant's mean walking distance was 652 m (SD ± 74). Their mean VO₂ max in GXT and O₂ uptake at the end of the 6MWT were 34·4 ml kg^-1 min^-1 (SD ± 7·6) and 27·2  ml kg^-1 min^-1 (SD ± 6·5), respectively. For men, the best predictors for VO₂ max were walking distance, age, BMI, heart rate at the end of 6MWT and height, and for women, walking distance, age and weight. The predictors explained 82% and 79% of men's and women's measured VO₂ max with the standard error of estimate of 3·6 ml kg^-1 min^-1 and 3·5 ml kg^-1 min^-1 , respectively.

The 6MWT performed along a 15-m track is a valid field test for predicting VO₂ max of healthy adults with accuracy of about 1MET.