The effect of external loading upon power output in stair climbing.

Previous studies have examined man's ability to produce external power output during maximal repetitive work cycles of short duration. It appears, however, that there were methodological limitations which would inherently mask man's true capacities. Consequently, we examined the effect of variable external loads upon external power output as measured by running upstairs. Fourteen male subjects (16-31 years of age) who regularly participated in competitive sports performed maximal stair step tests under five experimental loading conditions (no external load, 10.1, 19.2, 24.2, and 29.2 kg). Significant increases (P < 0.05) in external power output were found. External power output increased from a mean of 15.9 W x kg-1 +/- 1.0 (unloaded condition) to 18.5 W x kg-1 +/- 1.5 (external load of 29.2 kg). This is the first modern investigation demonstrating that external loads effect external power output as measured by this technique.