Accessible Exterior Surfaces Technical Article

Data Analyses

Net energy consumption – the additional energy utilized during walking in excess of resting levels – was calculated for each surface. Relative oxygen consumption values (ml O2/kg weight/min) measured during the data collection period (stable, plateau phase) were averaged for the resting data and each test surface. The net energy consumption (ml/kg/min) was calculated by subtracting the average resting value from the value for each test surface. The net energy consumption was divided by the velocity of walking in order to standardize the data for comparison between subjects. Thus, the energy consumption for each surface (oxygen consumption/kilogram of body weight/meter) was standardized relative to subject size (body weight), resting metabolic levels and speed of ambulation.

Frequency tabulations were used to identify data entry errors. T-tests and correlations were used to evaluate the relationships between numerical data. The impact of categorical data was evaluated using analysis of variance (ANOVA) statistics. Statistical significance was set at p < 0.05 for all analyses.