Using pedometers to measure moderate-to-vigorous physical activity for youth with an intellectual disability.

Background: Pedometers serve as one of the most feasible and cost-effective methods for frontline practitioners to measure moderate-to-vigorous physical activity (MVPA) of youth with an intellectual disability (YwID) but, historically, pedometers have been unable to measure MVPA. Technological advancements now allow pedometers to measure MVPA via step frequency (steps per minute). Translating the output of this technology into practical information that frontline practitioners and families can use, however, will require accurate step frequency guidelines.

Objective: The purpose of this study was to identify steps per minute thresholds corresponding to MVPA for YwID.

Methods: Thirty-eight children and adolescents (10 girls, 11.8 ± 1.8 years) attending a summer camp for youth with an ID walked on a treadmill starting at 2.0 mph and increasing every 2 minutes by 0.5 mph until they reached 4.0 mph. Youth were affixed with a heart rate (HR) monitor. Steps were counted by trained observers using hand-tally counters. Data were collected during the final minute of each speed. HR at each speed was transformed into percentage of heart rate reserve (%HRR), using each participant's resting HR. Percentage of HRR corresponding to 40%HRR or higher was used to define MVPA. Random effects models were constructed to predict steps per minute from %HRR and participant characteristics.

Results: The results indicated that, on average, 122 steps·min(-1) was the minimal threshold for MVPA. Height- and age-specific steps·min(-1) ranged from 135 steps·min(-1) to 112 steps·min(-1).

Conclusions: These findings provide preliminary thresholds for steps per minute that frontline practitioners working with YwID can use to promote and evaluate MVPA in this population.