Body-mass-modified running economy and step length in elite male middle- and long-distance runners.

To minimize the influence of body mass on oxygen uptake (VO2) during running, submaximal and maximal VO2 should preferentially be expressed as ml.kg-0.75.min-1. In this study, the levels of such body-mass-modified running economy were investigated at different velocities in elite runners and related to step lengths and anthropometric measures. Twenty-six Swedish National Team middle- and long-distance runners performed submaximal (4 velocities) and maximal treadmill tests. In 17 runners repeated (2-4) tests were performed within 6 months. The maximal oxygen uptake (VO2max; 214 vs 202 ml.kg-0.75.min-1) and running velocity at 4 mmol.l-1 blood lactate were higher in the long- (n = 12) than in the middle-distance group (n = 14). The oxygen uptake at 15 km.h-1 (VO2 15) was lower (129 vs 138 ml.kg-0.75.min-1, p < 0.01) and the VO2/velocity slope higher in the long-distance runners, with similar VO2 18 in the two groups. Step lengths at 18 (168 vs 173 cm) and 15 km.h-1 did not differ significantly between the groups, but the increase in step length per km.h-1 velocity raise was greater in the middle-distance runners. Step lengths at these velocities were positively related to body mass and stature, negatively to relative leg length. Stature and leg length were greater in runners displaying low VO2 15, whereas no corresponding difference was seen for VO2 18. The figures for running economy at 15 and 18 km.h-1 were poorly related to the concomitantly determined step lengths at the respective velocities.(ABSTRACT TRUNCATED AT 250 WORDS)