Klijn 2004.

Methods	Design: Single‐centre, parallel RCT, 3‐month duration. Inclusion criteria: Participants with CF aged 9 ‐ 18 years; a stable clinical condition (i.e., no need for oral or IV antibiotic treatment in the 3 months prior to testing); the absence of musculoskeletal disorders; and an FEV1 > 30 % predicted. Exclusion criteria: not specified.
Participants	20 participants with CF (stable disease) completed the study. Group demographics Group 1 (training) (n = 11): mean (SD) age 13.6 (1.3) years. Group 2 (control) (n = 9): mean (SD) age 14.2 (2.1) years. 3 participants dropped out; 1 withdrew from the training group for practical reasons (training group) and 2 from the control group as they did not complete assessments due to pulmonary exacerbations.
Interventions	Long‐term anaerobic study (12 weeks). Group 1: anaerobic exercise (2 days per week for 30 ‐ 45 min). Group 2: normal daily activities.
Outcomes	Included in this study were: BMI; FEV1; FVC; FEF25‐75; RV/TLC; Wingate Anerobic Test (PP, MP); VO2 peak; peak working capacity; VCO2; VE; RER; lactate; habitual activity estimation scale; HRQoL; fat‐free mass. Outcomes measured again at 12 weeks follow up.
Notes	To achieve a difference in PP per kg body weight of 10% with an SD of 0.8 W/kg and a statistical power of 80%, it was calculated that 8 participants had to be included in each study group.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, but no details of the method.
Allocation concealment (selection bias)	Low risk	Allocation concealed in opaque envelopes.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not possible to blind participants to intervention. The primary researcher was blinded but their role in the study is unclear.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	The primary researcher was blinded, but it is unclear whether this researcher was responsible for outcome assessment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Clear description and details about dropouts. 3 participants dropped out: 1 participant from the training group withdrew for practical reasons; 2 from the control group did not complete assessments due to pulmonary exacerbations. Intention‐to‐treat analysis was not performed.
Selective reporting (reporting bias)	Unclear risk	Results for HRQoL are only presented for the scale 'physical functioning' which was significantly higher in the training group after the 12‐week training period. No change in this HRQoL scale was observed in the control group after 12‐weeks. No significant effects were observed for any other HRQoL scales. Data were not reported in detail.
Other bias	Unclear risk	Clearly stated inclusion criteria but exclusion criteria were not reported. Described statistical methods used in analysis.