Limitations of oxygen uptake and leg muscle activity during ascending evacuation in stairways.

Stair ascending performance is critical during evacuation from buildings and underground infrastructures. Healthy subjects performed self-paced ascent in three settings: 13 floor building, 31 floor building, 33 m stationary subway escalator. To investigate leg muscle and cardiorespiratory capacities and how they constrain performance, oxygen uptake (VO), heart rate (HR) and ascending speed were measured in all three; electromyography (EMG) in the first two.