Background. Exercise capacity, muscle function, and physical activity levels remain reduced in recipients of lung transplantation. Factors associated with this deficiency in functional exercise capacity have not been studied longitudinally.
Objective. The study aims were to analyze the longitudinal change in 6-minute walking distance and to identify factors contributing to this change.
Design. This was a longitudinal historical cohort study.
Methods. Data from patients who received a lung transplantation between March 2003 and March 2013 were analyzed for the change in 6-minute walking distance and contributing factors at screening, discharge, and 6 and 12 months after transplantation. Linear mixed-model and logistic regression analyses were performed with data on characteristics of patients, diagnosis, waiting list time, length of hospital stay, rejection, lung function, and peripheral muscle strength.
Results. Data from 108 recipients were included. Factors predicting 6-minute walking distance were measurement moment, diagnosis, sex, quadriceps muscle and grip strength, forced expiratory volume in 1 second (percentage of predicted), and length of hospital stay. After transplantation, 6-minute walking distance increased considerably. This initial increase was not continued between 6 and 12 months. At 12 months after lung transplantation, 58.3% of recipients did not reach the cutoff point of 82% of the predicted 6-minute walking distance. Logistic regression demonstrated that discharge values for forced expiratory volume in 1 second and quadriceps or grip strength were predictive for reaching this criterion.
Limitations. Study limitations included lack of knowledge on the course of disease during the waiting list period, type and frequency of physical therapy after transplantation, and number of missing data points.
Conclusions. Peripheral muscle strength predicted 6-minute walking distance; this finding suggests that quadriceps strength training should be included in physical training to increase functional exercise capacity. Attention should be paid to further increasing 6-minute walking distance between 6 and 12 months after transplantation.