Aims: To determine the reproducibility of the distance covered in 3 min and its correlation with the 6 min walking test, as well as compare the distances covered at different time intervals. Secondly, to evaluate the relationship between the distances covered during these time periods and the maximum oxygen intake obtained during a bicycle ergometer test.
Methods: Forty-five Chronic Obstructive Pulmonary Disesase patients were included in the study. Subjects who were either physically limited or familiar with the test, or those with acute exacerbation in the month prior to the study, were excluded. Three walking tests were carried out each day. In 30 patients for three consecutive days, and the distances covered in periods of 3 and 6 min were measured with 20 min rest between each walk. No incentive was given and the patients knew that the distances covered in 3 and 6 min would be quantified. Oxygen saturation, heart rate and degree of breathlessness (modified Borg scale) were registered at baseline. After 3 min, the distance covered and degree of breathlessness were also measured. After 6 min, oxygen saturation, heart rate, degree of breathlessness and distance covered in meters were registered. Spirometry was performed daily on each patient, and those with an FEV1 variation of less than 10% were considered clinically and functionally stable. An exercise test using bicycle ergometer was carried out to determine maximum oxygen intake. A 3 min walking test was performed in 15 patients, independently on the same day, which was followed after 20 min rest with a 6 min walking test.
Results: A significant increase was observed in the distance covered over 3 and 6 min in the first 5 walks, with the greatest increase seen in the first 3 walks. The correlation between the distance covered in 3 and 6 min was 0.98. The correlation between the distance covered in 3 min and oxygen intake was 0.64. No significant differences were observed between the distances covered in the 0-3 and 3 to 6 min periods. During the walking test, breathlessness was measured using the modified Borg scale, which was 1.8 after 3 min, and 3.2 after six min and 8.6 at the end of bicycle ergometer test. No significant differences were observed between the distance covered during the 3 minute test and the distance in the first 3 min of the 6 min walking test.
Conclusions: A learning effect was observed when the walking test is carried out repeatedly over short time periods, with a significant increase in the first 5 walks. Correlation between the distances covered in 3 and 6 min is very good, and acceptable when the distance covered over these periods is compared with oxygen intake and walking speed is constant.