['Cystic fibrosis (CF) lung disease leads to progressive deterioration in exercise capacity. Because physical activity has been shown to improve lung function and quality of life (QoL), developing routine exercise programs can benefit this patient population.', "Lung function, nutritional status, and exercise capacity and assessments of habitual activity and QoL were measured before and after a two-month, subject-designed exercise regimen based on self-reported activity assessment. Statistical analysis included Wilcoxon signed-rank, Wilcoxon rank sum, and Fisher's exact tests.", 'Subjects completing the study demonstrated significant improvement in exercise capacity and body image perception, a CF-specific QoL measure (p<0.001). In secondary analyses, subjects improving exercise capacity showed significant increases in lung function and self-reported habitual activity.'] Does exercise improve lung function and habitual activity in children with cystic fibrosis?