School Based Pedometer Intervention

Intervention outcomes, expressed by mean changes, often overlook variable responsiveness. This may mask some intervention successes. PURPOSE: To explore individual variability in children completing a pedometer intervention. METHODS: Six schools (n=152) were ranked and paired by socio-economic status, with one per pair randomly allocated to a six-week teacher-led pedometer intervention (PI, n=81) or control (C, n=71). Actigraph GT1M accelerometers assessed physical activity (PA) for 7 days. Evenson cut points identified total daily sedentary (SED), light PA (LPA) and moderate-to-vigorous PA (MVPA) expressed as percentage (%) of total daily wear time. For analysis, a PA return of 480+ mins/d, ≥3 school days for pre and post-tests was needed. Mean pre daily MVPA mins were used to categorise subgroups; Non-Achievers <30 (NA1), NA 31–44 (NA2), NA 45–59 (NA3), Achievers >60 (ACH). RESULTS:From 84 included participants (F=60%, 9.9±0.3yrs), no significant differences were found between PI (n=52) and C (n=32) for increases in % time in MVPA (0.30±.67 v 0.13±2.39), LPA (2.03±4.63 v -0.05±4.25) and reducing % of SED time (2.33±5.89 v -0.08±5.52). More PI (17 to 27%) than C (16 to 19%) pupils met 60mins/d guidelines.Versus C, two PI groups improved MVPA. The greatest increases were in NA1 (1.52% above C) and +2.05±2.34% from pre-test. PI-ACH decreased % time in MVPA from pre to post (-2.75±2.85%). All PI subgroups increased % time spent in LPA versus C, with NA2 improving 3.54% above C and PI-NA1 having the greatest improvement (+3.60±6.37%). All PI groups had more favourable SED results; three reducing SED time. The greatest reduction versus C was NA3 (3.95%). The greatest total reduction was in PI-NA1 (-5.65±7.80%). Greater proportions of participants met the 60mins/d guidelines in three PI groups versus C. The largest increase was seen in NA3 (+31%); both ACH groups showed a decline (PI 100 to 67%; C 100 to 40%). CONCLUSIONS: Despite no significant overall PI effects versus C, a greater % of participants met the 60mins/d guidelines. PI found clusters of responsiveness. Pre-PI NA benefited most demonstrating positive changes in eight of nine activity outcomes compared to C, maybe at the expense of the most active. While participant numbers are small, they justify examining sub-population variability in subsequent research.