Objectives: To report the results obtained in six-minute walk tests (6 MWT) performed in a group of patients under a pulmonary rehabilitation program (PRP) as a contribution to a better interpretation and the proper use of this test. Some factors that interfere with physical training during pulmonary rehabilitation were also studied. Methods: Retrospective data on 18 males and 5 females under a PRP were evaluated. During 3 months, the patients had 3 weekly training sessions to exercise the muscles of the lower extremities. The following parameters were analyzed before and after training: the distance walked during the 6 MWT and its relationship with the reference values calculated by the equations of Enright and Sherril; forced expiratory volume in one second, training load, heart rate (HR), respiratory rate (RR), oxygen saturation by pulse oxymeter (SpO2) and body mass index (BMI). Results: The values obtained during pre-training 6 MWT did not differ from the reference values calculated by Enright and Sherril equations (P = 0.777). After training, these values differed significantly (P = 0.001). The mean 6 MWT distance increase was 76 m. However, 3 patients did not reach the minimally significant increase of 54 m. Post-training 6 MWT correlated positively with pre-training FEV1 (P = 0.012), but not with load increase during training (P = 0.693). No significant difference in RR and SpO2 was observed before and after training. HR increased significantly at the end of post-training 6 MWT (P = 0.035). In 9 patients BMI was lower than the inferior limit. Six of them (66%) presented post-training distance increased in 54 m or more. Conclusions: The use of standardized methods for 6 MWT performance is recommended, even when reference values are targeted. The equations of Enright and Sherril for healthy subjects tended to yield underestimated values, with no statistical differences in training values in COPD patients. Differences in the encouragement technique employed could explain these conflicting results. Physical gain after rehabilitation was confirmed regardless of the patient's initial functional status, justifying the indication of rehabilitation even to those with severe respiratory limitations. The heterogeneous responses to load increase suggest the analysis of the predictive factors of the best response to training is necessary to customize load increase and thus obtain the best performance possible.
Exercise test; Obstructive lung diseases; Rehabilitation; Respiratory function tests; Exercise
