Reliability and Intensity of the Six-Minute Walk Test in Healthy Elderly Subjects

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Abstract
KERVIO, G., F. CARRE, and N. S. VILLE. Reliability and Intensity of the Six-Minute Walk Test in Healthy Elderly Subjects. Med. Sci. Sports Exerc., Vol. 35, No. 1, pp. 169–174, 2003. Purpose The 6-min walk test (6-MWT) is an easy and validated field test, generally used in patients to assess their physical capacity. We think that the 6-MWT could also be conducted in the same perspective in healthy subjects, aged 60–70 yr. However, little is known about the effect of the familiarization on the 6-MWT performance and the relative intensity of this test. The aims of this study were therefore to bring precision to the 6-MWT reliability and intensity in this population. Methods Over 3 d, 12 subjects performed two maximal exercise tests on treadmill and five 6-MWT (two in the morning and three in the afternoon) with a portable metabolic measurement system (Cosmed K4, Rome, Italy). The distance, walking speed, oxygen uptake (V̇O2), and heart rate (HR) values were measured during the 6-MWT. Results Distance, walking speed, and V̇O2 were only lower during the first two 6-MWT (respectively, P < 0.001, P < 0.001, and P < 0.05). HR was reliable from the first 6-MWT and was higher during the tests performed in the afternoon (P < 0.001). The intensity of the 6-MWT corresponded to 79.6 ± 4.5% of the V̇O2max, 85.8 ± 2.5% of the HRmax, and 78.0 ± 6.3% of the HRreserve. Moreover, it was higher than the ventilatory threshold in each subject (P < 0.01). Conclusion In healthy elderly subjects, the 6-MWT represents a submaximal exercise, but at almost 80% of the V̇O2max. To be exploitable, two familiarization attempts are required to limit the learning effect. Finally, the 6-MWT time of day must be taken into account when assessing HR.