Comparison of walking parameters and cardiorespiratory changes during the 6-minute walk test in healthy sexagenarians and septuagenarians.

BACKGROUND: The 6-minute walk test (6-MWT) is commonly used in research, with a focus on walking distance parameters rather than the physiological parameters. Even though it has been reported that the distance walked during the 6-MWT decreases with age, the adaptation of cardiorespiratory functions in healthy older adults remains to be studied.

OBJECTIVES: The primary objective of this study was to compare the changes in walking distance and cardiorespiratory parameters during the 6-MWT in healthy sexagenarians and septuagenarians. A secondary objective was to determine the cardiorespiratory parameters and functional performance variables that best predict the distance covered during the 6-MWT.

METHODS: Ten healthy sexagenarians (G60, mean age 63.6 +/- 3.3 years) and 10 septuagenarians (G70, mean age 76.0 +/- 3.3 years) performed the 6-MWT while the distance, heart rate and oxygen uptake (VO(2)) were recorded. The subjects also completed the Timed-Up-and-Go, the Berg Balance Scale and the Human Activity Profile to establish their functional level.

RESULTS: Results showed that G60 reached significantly greater (p < 0.05) distance and VO(2) values during the 6-MWT than G70. In contrast, the energy cost of walking (O(2) cost) and heart rate did not differ between the 2 groups. Correlational analyses of the combined groups revealed that VO(2) was the variable that showed the strongest correlation with walking distance during the 6-MWT.

CONCLUSION: Results revealed that, while G60 achieved a greater level of walking performance than G70, the 2 groups maintained the same level of walking efficiency (O(2) cost) during the walk. Both groups adjusted their walking speed to have an oxygen consumption rate at a level sufficient to meet the energy demands of the task and prevent early exhaustion. Therefore, the 6-MWT appears to be a simple tool that can be used to assess cardiorespiratory parameters in older adults and be sensitive enough to detect differences between sexagenarians and septuagenarians.