Pedometer accuracy during walking over different surfaces.

PURPOSE: This study examined the effect of surface (concrete, grass, dry beach sand, wet beach sand) and gender on pedometer accuracy during walking.
METHODS: Fifty-two healthy university students volunteered for this study and completed six 150-m walking trials for each of the four different surfaces while wearing a YAMAX SW-700 Digiwalker pedometer. For each trial, time, number of steps taken and number of steps registered by the pedometer were recorded. These variables and pedometer accuracy for each walking surface and gender were analyzed by two-way repeated-measures ANOVA and Tukey's post hoc tests.
RESULTS: Walking over dry beach sand significantly reduced walking speed (concrete, 5.6 +/- 0.5 km.h(-1); grass, 5.6 +/- 0.5 km.h(-1); dry beach sand, 5.0 +/- 0.5 km.h(-1): wet beach sand, 5.4 +/- 0.4 km.h(-1)) and increased the number of steps taken (concrete, 190 +/- 13; grass, 186 +/- 12; dry beach sand, 207 +/- 12; wet beach sand, 194 +/- 11) and registered (concrete, 195 +/- 14; grass, 191 +/- 14; dry beach sand, 213 +/- 15; wet beach sand, 201 +/- 16) by the pedometer compared with concrete and grass. Compared with males, females registered a greater number of pedometer steps (204 +/- 18 vs 197 +/- 15) and a greater absolute (9 +/- 12 vs 3 +/- 7 steps) and relative (4.46 +/- 5.72 vs 1.63 +/- 3.57%) pedometer error during walking over dry beach sand.
CONCLUSIONS: Walking on a soft surface such as dry beach sand significantly reduced walking speed and increased pedometer error for females compared with males, possibly by exacerbating hip and walking movements. Identification of gender and softer surfaces should be considered when documenting physical activity levels in field studies.