Process evaluation for a school-based physical activity intervention for 6th- and 7th-grade boys: reach, dose, and fidelity.

The purpose was to evaluate the reach, dose, and fidelity of Guys Only Activity for Life (G.O.A.L.), a 7-week pilot intervention conducted from February to March 2011 to increase 6th and 7th grade boys' moderate-to-vigorous physical activity (MVPA). One middle school was randomly assigned to the G.O.A.L. intervention and another from the same urban school district in the Midwestern U.S. to a comparison condition. Thirty boys, ages 10-14 years, participated in each school. The intervention, guided by the Health Promotion Model (HPM) and Self-Determination Theory (SDT), consisted of a 90-min after-school physical activity club 4 days/week and one motivational interviewing session with a registered (school) nurse. Data were gathered via attendance records, club observations, heart rate monitors, audio-taping of motivational interviewing sessions, and surveys. On average boys attended the club 2.11 days/week (SD=.86). A trained independent process evaluator reported that the physical activity club instructors provided the boys with the opportunity for a mean of 25.8 min/day of MVPA. Using a four-point Likert scale (1=disagree a lot; 4=agree a lot), the process evaluator perceived that the club was delivered with high fidelity and adherence to the underlying theories (M=3.48; SD=0.39). Sessions with the nurse lasted an average of 13 min, 29 s. All boys attended. Two trained independent coders indicated that the nurse demonstrated at least beginning proficiency for all tasks associated with motivational interviewing, with the exception of using sufficient open- as opposed to closed-ended questions and reflections compared to questions. Fidelity related to session delivery and adherence to the theories was high (M=3.83; SD=0.19). The process evaluation data indicated that strategies are needed to increase attendance and boys' MVPA during the club time.