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Table 2 Methodological characteristics (delivery) of three key SDT-based intervention trials for PA promotion.

From: Promoting physical activity: development and testing of self-determination theory-based interventions

Descriptor PAC Trial Empower Trial PESO Trial
Randomization - Participants randomized to 2 groups (statistician-created sequence): BPAC = brief or IPAC = intensive).
- Stratified by gender & age.
- 13 leisure centres with EoP randomized to 2 arms (statistician-created sequence): standard practice (control) or SDT-based intervention
- Stratified by Primary Care Trust (PCT) and deprivation of
population served
Participants from 3 annual cohorts randomized (Excel 2007 random number generator function) to 2 groups: experimental (SDT-based intervention) or control.
Interventionist(s) - BPAC (control) by HCP.
- IPAC by PA counsellor (part of health care team; exercise science degree).
- Control/intervention: HFAs at community leisure centres.
- HFAs: Level 3 National Occupational Standards.
Intervention (staff): 6 Ph.D. or M.S. level exercise physiologists, nutritionists, dieticians, & psychologists.
Control: invited lecturers
Interventionist(s) training - BPAC (HCP): 3 training seminars (SDT-based delivery of first 4A's of 7A's model; [3])
- IPAC (PA counsellor): 2-month autonomy-support & MI training (last 3 A's) + counselling skills + bi-weekly supervision.
- Control HFAs: Training Day One (see [11]) + 2nd training meeting (on topic of recruitment).
- Intervention HFAs: Training Day One & Two + 1/2 day (theory, client-centered communication, creating autonomy-supportive climate).
- Intervention staff: 2-day-long workshop and 4-6 training meetings provided by in-house SDT experts and by one external MI expert.
- Control: no specific weight control or behavior change/SDT training
Intervention duration/
- IPAC: BPAC + intensive 3-month PA-counselling (last 3 A's; 6 sessions, every 2 weeks).
- IPAC sessions: 3 in-person, 3 conducted by phone; see [3] for format/order of sessions).
- Control/intervention: initial 1 hour consultation + 3-month program (6-month follow-up).
- One-on-one contacts (3) each month; telephone or in-person; intended: 5 to 30 min per contact.
- Consistent across groups.
- One-year intervention (group-based); 2-year follow-up.
- Thirty (29 for control) weekly or bi-weekly sessions of 120-min each.
Control group BPAC: 2-4 minute PA intervention delivered by HCP (first 4 A's of 7A's + PA prescription). Standard practice (control) of each EoP leisure centre provided by HFA without SDT training. General health education curriculum (themed courses including stress management, food safety and preventive nutrition, interpersonal relationships, etc.).
  1. Abbreviations: BPAC = Brief physical activity counselling; IPAC: Intensive physical activity counselling, PA = physical activity; EoP = Exercise on prescription; SDT = Self-determination theory; HCP = Health care provider(s); HFA = health and fitness advisor; MI = Motivational interviewing