(Montana State University - Bozeman, College of Education, Health & Human Development, 2007) McKenzie, James Michael; Chairperson, Graduate Committee: Daniel P. Heil
The purpose of this study was to determine the ability of GPS-reported position and elevation to estimate actual energy expenditure (EEACT) for outdoor walking. An accurate method for assessing EE in the field could greatly influence the scope of future studies of free-living activities. Thirteen subjects (8 male, 5 female) completed a 2303 m course of varying grades at slow and fast self-selected paces. Data from a portable metabolic unit was used to compare the GPS-predicted EE (EEGPS). Calculations of EEGPS were made by compiling an equation accounting for ground speed, grade, (Minetti, et al., 2002) and wind resistance (Pugh, 1970). Differences between EEACT and EEGPS were statistically and practically significant for the slow walking trials. Fast trials showed no significant differences. The combined data differed significantly from EEACT, but was similar to the error for accelerometer-based activity monitors. The wrist and hip-worn GPS monitors provided similar results for EEGPS throughout the data set. Separating the data by grade type showed that EEGPS was most problematic for uphill walking.
