Energetics of best performance in middle distance running.

Oxygen consumption (VO2) and blood lactate concentration were determined during constant-speed track running on 16 runners of intermediate level competing in middle distances (0.8-5.0 km). The energy cost of track running per unit distance (C(r)) was then obtained from the ratio of steady-state VO2, corrected for lactate production, to speed; it was found to be independent of speed, its overall mean being 3.72 +/- 0.24 J . kg-1 . m-1 (n = 58; 1 ml O2 = 20.9 J). Maximal VO2 (VO2max) was also measured on the same subjects. Theoretical record times were then calculated for each distance and subject and compared with actual seasonal.best performances as follows. The maximal metabolic power (E(rmax)) a subject can maintain in running is a known function of VO2max and maximal anaerobic capacity and of the effort duration to exhaustion (t(e)). E(rmax) was then calculated as a function of t(e) from VO2max, assuming a standard value for maximal anaerobic capacity. The metabolic power requirement (E(r)) necessary to cover a given distance (d) was calculated as a function of performance time (t) from the product C(r)dt-1 = E(r). The time values that solve the equality E(rmax) (t(e)) = E(r)(t), assumed to yield the theoretical best t, were obtained by an iterative procedure for any given subject and distance and compared with actual records. These calculations, applied to our data and to similar data obtained by Lacour et al. (Eur. J. Appl. Physiol. Occup. Physiol. 60: 38-43, 1990) on French elite athletes, show good agreement between actual and calculated best t values; their ratio was 1.078 +/- 0.095 (n = 41) and 1.026 +/- 0.0042 (n = 68), respectively, over distances from 800 to 5,000 m.