Shulman 2013.

Methods	Randomised controlled trial Method of randomisation: random number generator Blinding of outcome assessors: yes Adverse events: none Deaths: none Drop‐outs: 13 (4 from experimental group I, 3 from experimental group II and 6 from control group) ITT: no
Participants	Country: USA 80 patients (26 from experimental group I, 26 from experimental group II and 28 from control group) Ambulatory at study onset: not described Mean age: 65 to 66 years (control and treatment group respectively) Inclusion criteria: aged 40 and above, diagnosis of PD characterized by asymmetrical onset of at least 2 of 3 cardinal signs, Hoehn & Yahr stage 1 to 3, presence of gait or balance disturbances, Mini‐Mental State Examination >23 Exclusion criteria: unstable medical or psychiatric conditions, aerobic training prior to study enrollment
Interventions	3 arms: (1) control group used stretching and resistance training, 3 times a week for 12 weeks (duration of sessions not described) (2) experimental group I received lower intensity treadmill exercise, 3 times a week for 12 weeks (150 min a week) (3) experimental group II received higher intensity treadmill exercise, 3 times a week for 12 weeks (90 min a week)
Outcomes	Outcomes were recorded at baseline and at the end of intervention phase Primary outcome measures: Gait speed (6‐min walk test, 10m walk test) cardiovascular fitness (ergospirometry) muscle strength (1‐repetition maximum strength)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	method of sequence generation not described by the authors
Allocation concealment (selection bias)	Unclear risk	not described by the authors
Blinding of outcome assessment (detection bias) All outcomes	Low risk	physicians and staff were blinded as described by the authors
Incomplete outcome data (attrition bias) All outcomes	Low risk	missing outcome data balanced between groups with similar reasons for missing data across groups