Hommerding 2015.

Methods	Design: Single‐centre parallel RCT; 3‐month duration Inclusion criteria: participants with CF aged 7 ‐ 20 years; stable disease, no signs of exacerbation of respiratory symptoms in last 15 days. Exclusion criteria: cognitive impairment, non CF‐related bone and muscle abnormalities, heart disease with haemodynamic instability.
Participants	34 participants with CF (20 boys, 14 girls). Group demographics Exercise group (n = 17): mean (SD) age 13.4 (2.8) years. Control group (n = 17): mean (SD) age 12.7 (3.3) years.
Interventions	Aerobic exercise program based on verbal and written guidelines. Exercise group: participants took part in a 3‐month aerobic exercise training program based on verbal and written guidelines. The program included exercises such as jogging, swimming, walking, ball games and stretching exercises. Participants were told to practice the exercises at least twice a week for at least 20 min. No recommendations were provided regarding exercise intensity. Participants received telephone calls every 2 weeks and instructions were provided by one of the authors. Control group: Participants were instructed about aerobic exercises once at baseline according to the CF center routine.
Outcomes	Included in this study were: VO2 peak; FVC; FEV1; FEV1/FVC; FEF25‐75; HRQoL; self‐reported physical activity; body weight; BMI z score; triceps skinfold thickness; arm muscle circumference; SaO2 at rest and peak exercise, treadmill time; treadmill speed; peak HR; Borg breathlessness and fatigue.
Notes	The sample size was estimated based on a mean (SD) change of 18.1 (13.8) points in the physical score of the HRQoL questionnaire. The estimated sample size was 15 participants in each group (95% power at a 5% level of significance). 2 more participants were included in each group to account for potential dropouts. Another study from the same group using the same aerobic exercise program was published recently (Schindel 2015). The responsible author of this publication confirmed that the vast majority of included participants were the same as in the Hommerding study (Hommerding 2015). There were only marginal differences in lung function (FEV1, FVC and FEF25‐75) compared to the Hommerding study for which reasons we decided not to include lung function data in this review.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were allocated to the intervention or control group in blocks of 6. A computer‐based program was used for randomisation.
Allocation concealment (selection bias)	Unclear risk	Not discussed.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not possible to blind participants to intervention. Unclear whether personnel was blinded.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear whether outcome assessors blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No drop outs were reported during the study.
Selective reporting (reporting bias)	Unclear risk	Blood pressure was measured prior to and after cardiopulmonary exercise testing but not reported. HR at rest and SaO2 at peak exercise were measured but results were not reported at baseline.
Other bias	Unclear risk	No validity criteria for maximal performance during cardiopulmonary exercise testing were reported in the methods. The mean (SD) peak heart rate reached during the exercise test was 157.1 (38.5) beats per min in the training group and 167.7 (20.8) beats per min in the control group, indicative of a submaximal effort. This likely underestimates the true VO2 peak of the study participants.