Performance and perception at various combinations of treadmill speed and slope.

Three healthy young adult males were placed on a treadmill at 5 X 5 combination of speed and slope. They were instructed that the session would end when they had climbed 300 m. The results showed that the subjects' operant choices resulted in a quasi-constant duration of sessions, i.e., they tended to walk at constant power. Such a choice could be predicted from the sum of ratings for displeasure in the chest plus displeasure in the lower limbs. It is therefore likely that this bidimensional perception was the cue for working at constant power.