Evaluation of Margaria staircase test: the effect of body size

The purpose of this study was to evaluate the methodology of Margaria staircase test (MT) for assessment of muscle anaerobic power. Specifically, we hypothesized that due to the scaling effects the outcome of MT calculated using the standard formula that suggests the power output to be proportional to body mass [P = (m · g · h)/T; P = power output, m = body mass, g = 9.81 m/s², h = height of stairs climbed, T = running time] overestimates the effect of body size on the calculated muscle power output. Young and physically active subjects (N = 111) were tested and the relationship between P and body size (S; either body mass or height) was assessed by standard allometric model (i.e., P = a · S ^b ; where a and b were the constant multiplier and allometric parameter, respectively). The results supported the hypothesized relationship by revealing b = 0.66 (95%CI = 0.49–0.83; r = 0.59; P < 0.001) and b = 1.13 (95%CI = 0.49–0.83; r = 0.34; P < 0.001) for body mass and body height, respectively. The obtained values of b (i.e., b < 1 for body mass and b < 3 for body height) suggest that the standard formula of MT overestimates the power output of larger subjects and underestimates the power of smaller ones. Since the results were mainly in line with both the experimental findings and theoretical predictions regarding the general effects of scale on human muscle power, we propose a modified formula that provides normalized power: P _n = P/m ^0.67 = [(m · g · h)/T]/m ^0.67 = (m ^0.33 · g · h)/T. The modified formula could provide a body size independent index of muscle power that would both allow for establishing standards and enable comparison of individuals and groups of individuals of different body dimensions.