Brandon, L. J. (1995). Physiological factors associated with middle distance running performance. Sports Medicine, 19, 268-277.

Middle distance running is completed at higher intensities than long distance running and lower intensities than sprint events. It involves distances from 800 to 3000 m. It is influenced by a number of physiological variables.

Owing to the high intensity and duration of middle distance races, runners incur an energy cost that is larger than the capabilities of either aerobic or anaerobic metabolism. Energy contributions from the two systems are made simultaneously during an event.

It has been shown that: the energy cost per meter run during competition in a 400 m event (46.5 sec) was 30% greater than the energy cost of running a competitive 800 m (1:46.1). [Lacour, J. R., Bouvat, E., & Barthelemey, J. C. (1990). Post-competition blood lactate concentrations as indicators of anaerobic energy expenditure during 400-m and 800-m races. European Journal of Applied Physiology, 6, 172-176.]

The importance of the two energy systems changes, not only for different events but also for the same distance for runners who possess different physiological abilities.

The average VO2max for elite middle distance runners ranges between 68 and 77 ml/kg/min. These values are lower than those of long distance runners but middle distance runners compete at a higher percentage of VO2max and incur a greater energy cost for unit distance run. They have the ability to compete at intensities up to 110% of VO2max for as long as 10-11 minutes, while long distance runners typically compete at intensities between 75 and 90% of VO2max. The relationship of VO2max to middle distance performance is lower than it is for long distance performance. This relationship is lowest at 800 m and highest at 3000 m, because of the greater importance of anaerobic contributions at the shorter distance.

The ability to work efficiently at a high fraction of VO2max without an accumulation of lactic acid can determine success among runners who are relatively homogeneous with respect to other aerobic factors. There are limitations to the increases possible for VO2max and gains in endurance performances can be independent of VO2max. Runners with high anaerobic thresholds (ANTh) are capable of performances that are superior to those of runners who have an even higher VO2max, but a lower ANTh.

ANTh has been shown to relate to running velocity for distances over 5000 m but not to relate to distances such as 800 m. Therefore, it is considered to be less important for middle-distance events than for long-distance events.

Anaerobic capacity (the maximum capacity to deliver anaerobic energy) is more important for the longer middle distance events while anaerobic power (the maximum rate of delivering anaerobic energy) allows runners to compete at a faster velocity for a longer period of time. Generally, middle distance runners have a larger anaerobic capacity than do long distance runners.

Implication. Middle distance runners are not restricted to a set of defined physiological attributes for performances. Various mixes of aerobic and anaerobic variables produce champions. However, those same champions are usually higher than normal in both aerobic and anaerobic capacities, which contributes to their superiority. The major factor that distinguishes elite from lesser performers is the economy of movement exhibited at racing speeds, a phenomenon which is not reflected at slower speeds. The technique of running fast has a lot to do with middle distance running success. Running economy is the determinant of success among runners with very similar VO2max values.

Contributions from running economy are different for middle distance runners than for distance performers. They can run at higher velocities with a better economy than at lower velocities.

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