Heart rate over time during four stairway ascents and three descents.

<p>The black line represents ascending the stairs one stair step at a time (with alternate feet) while the grey line represents ascending two stair steps at a time. The grey bars represent the final 30 second periods of the second and third ascents of the one step climbing, from which a mean heart rate was obtained to estimate rate of oxygen consumption during stair ascending one stair step at a time. The same method was employed for two step climbing.