To study the effects of an 8-week combined inspiratory muscle training and exercise (resistance+aerobic) program on of a lung volume, inspiratory muscle strength (maximal inspiratory pressure, PImax) and cardiorespiratory fitness (maximal oxygen uptake, VO2peak) (primary outcomes)and dynamic muscle strength, body composition and quality of life (QoL) in children with Cystic Fibrosis (CF) (secondary outcomes).