Effects of Speed and Grade Change on the Ability to Reproduce a Standard Work Effort.

The purpose of the study was to investigate the ability of subjects to reproduce the “feeling” of a standard treadmill exercise task under conditions of changing speeds and grades. Subjects (12 males, 9 females) first performed a standard treadmill run (6.0 mph, 0% slope) and then a run in an experimental condition of either a variable-grade, fixed-speed (3.5 mph) or a variable-speed, fixed-grade (5%). Under the experimental conditions subjects attempted to adjust the speed or grade so as to reproduce the work effort they had exerted on the standard exercise task. Results showed that the O2, CO2, E and HR under the fixed grade-variable speed condition were significantly greater than under the other conditions. While running up an incline at a speed chosen by themselves, subjects apparently will perceive the work effort to be the same as running on the level, when in fact it is costing them more energy.