title: What is the impact of obtaining medical clearance to participate in a randomised controlled trial examining a physical activity intervention on the socio-demographic and risk factor profiles of included participants?
abstract: Requiring individuals to obtain medical clearance to exercise prior to participation in physical activity interventions is common. The impact this has on the socio-demographic characteristic profiles of participants who end up participating in the intervention is not clear.
  
  
  
  As part of the multi-component eligibility screening for inclusion in a three-arm randomised controlled trial examining the efficacy of a web-based physical activity intervention, individuals interested in participating were required to complete the Physical Activity Readiness Questionnaire (PAR-Q). The PAR-Q identified individuals as having lower or higher risk. Higher-risk individuals were required to obtain medical exercise clearance prior to enrolment. Comparisons of the socio-demographic characteristics of the lower- and higher-risk individuals were performed using t tests and chi-square tests (p = 0.05).
  
  
  
  A total of 1244 individuals expressed interest in participating, and 432 were enrolled without needing to undergo further screening. Of the 251 individuals required to obtain medical clearance, 148 received clearance, 15 did not receive clearance and 88 did not return any form of clearance. A total of 105 individuals were enrolled after obtaining clearance, and the most frequent reason for being required to seek clearance was for using blood pressure/heart condition medication. Higher-risk individuals were significantly older, had a higher body mass index and engaged in more sedentary behaviour than lower-risk individuals.
  
  
  
  Use of more inclusive participant screening protocols that maintain high levels of participant safety are encouraged. Allowing individuals to obtain medical clearance to participate can result in including a more diverse population likely to benefit most from participation.
  
  
  
  Australian New Zealand Clinical Trials Registry ( ACTRN12611000157976 ). Registered on 9 February 2011.
authors.affiliation: School of Medicine and Public Health, Priority Research Centre for Physical Activity and Nutrition, Faculty of Health and Medicine, University of Newcastle, Newcastle, NSW, Australia. mitch.duncan@newcastle.edu.au.
authors.forename: Mitch J
authors.initials: MJ
authors.lastname: Duncan
authors.affiliation: Department of Food, Nutrition, Dietetics and Health, Kansas State University, Manhattan, KS, USA.
authors.forename: Richard R
authors.initials: RR
authors.lastname: Rosenkranz
authors.affiliation: School of Human Health and Social Sciences, Central Queensland University, Rockhampton, QLD, Australia.
authors.forename: Corneel
authors.initials: C
authors.lastname: Vandelanotte
authors.affiliation: School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada.
authors.forename: Cristina M
authors.initials: CM
authors.lastname: Caperchione
authors.affiliation: School of Human Health and Social Sciences, Central Queensland University, Rockhampton, QLD, Australia.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Rebar
authors.affiliation: School of Health Science, Flinders University, Adelaide, SA, Australia.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Maeder
authors.affiliation: School of Computing, Engineering and Mathematics, Western Sydney University, Sydney, NSW, Australia.
authors.forename: Rhys
authors.initials: R
authors.lastname: Tague
authors.affiliation: School of Science and Health, Western Sydney University, Sydney, NSW, Australia.
authors.forename: Trevor N
authors.initials: TN
authors.lastname: Savage
authors.affiliation: School of Human Health and Social Sciences, Central Queensland University, Rockhampton, QLD, Australia.
authors.forename: Anetta
authors.initials: A
authors.lastname: van Itallie
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB, Canada.
authors.forename: W Kerry
authors.initials: WK
authors.lastname: Mummery
authors.affiliation: School of Science and Health, Western Sydney University, Sydney, NSW, Australia.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Kolt
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002317:Cardiovascular Agents / Q000627:therapeutic use; D016009:Chi-Square Distribution; D005081:Exercise Therapy / Q000009:adverse effects / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D009517:New South Wales; D061214:Patient Safety; D018579:Patient Selection; D010809:Physical Fitness; D011793:Queensland; D035842:Research Subjects; D018570:Risk Assessment; D012307:Risk Factors; D057185:Sedentary Behavior; D011795:Surveys and Questionnaires; D016138:Walking
chemical_list: D002317:Cardiovascular Agents
keywords: Medical clearance; Participant characteristics; Physical activity; Randomised controlled trial; Recruitment