Klijn 2004.

Study characteristics
Methods	Randomised controlled study.
Participants	23 children with CF with a stable clinical condition (no requirement for oral or IV antibiotics in the 3 months preceding study testing; FEV1 >30%; absence of musculoskeletal disorders).
Interventions	Intervention Group Intervention group participants received individual anaerobic training, supervised by a physiotherapist. 2 sessions per week for 12 weeks. Control Group Contol group participants were asked not to change their normal daily activities.
Outcomes	Body composition: fat‐free mass; body weight (kg); BMI. Pulmonary function tests (% predicted): FEV1; FVC; FEF25-75; RV/TLC. Peripheral muscle strength (isometric muscle force): presented as the total maximal muscle force (i.e. summed maximal force in all 4 muscle groups assessed). Anaerobic performance: Wingate anaerobic test (WanT) (mean power and peak power presented). Aerobic performance: standard, incremental progressive exercise test (bike) (VO2 peak ‐ ml/kg/min). Lactate: via blood sample drawn 3 minutes after peak aerobic exercise (mmol/L). Daily physical activity: Habitual Activity Estimation Scale (HAES). Total percentage of time active presented. QOL: CF questionnaire (CFQ).
Notes	3 children withdrew ‐ results of remaining 20 participants presented.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated.
Allocation concealment (selection bias)	Low risk	Use of concealed envelopes.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Participants and physiotherapists conducting exercise training sessions aware of group allocation, the nature of the intervention would make this type of blinding difficult.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	The paper notes that the primary researcher was blinded to group allocation, however, it is unclear whether this researcher undertook the outcome assessments.
Incomplete outcome data (attrition bias) All outcomes	Low risk	3 dropouts are reported (1 from the treatment group, 2 from the control group). There was no intention‐to‐treat analysis.
Selective reporting (reporting bias)	Unclear risk	Access to the protocol was unavailable. Results are presented for only one domain on the QOL assessment.
Other bias	Unclear risk	The discussion section of the paper states "participants were asked not to change their activity level during the study period", however the means by which this was instructed and the proposed effect are not stated in the methods of the paper.