The metabolic and muscular differences between two stair-climbing strategies of young adults

When climbing stairs, there are 2 practical strategies, contact each step with alternating feet (single) or contact every other step (double) with alternating feet. Our purpose was to evaluate the metabolic cost and muscular activity of these single and double stair-climbing strategies. We hypothesized that metabolic cost would not differ between the 2 strategies, because the subjects would complete the 2 protocols with a similar speed that would minimize cost. Likewise, we hypothesized that muscle activity during stance would not differ between the 2 stepping strategies. Twelve subjects completed baseline and experimental protocols. For the baseline protocol, the subjects walked up a stairwell with a single-step and a double-step strategy. For the experimental protocol, each subject walked on a treadmill inclined to the same degree as the stairs at the speed and step frequency determined from the baseline protocol. Every subject completed the baseline testing with a faster average speed during the double-step protocol. After mimicking each strategy with our experimental methods, we calculated that the double-step strategy would yield a greater use of metabolic energy, equal to approximately 1.0-1.3 kcalxkg-1xh-1, on average 70-90 additional kcalxh-1. This double-step strategy required a greater activity for propulsion during stance for the ankle and knee extensors. In summary, to maximize metabolic cost and muscular activity, we recommend a double-stair-climbing (skip a step) strategy.