Training induced physiological and metabolic changes associated with improvements in running performance.

The purpose of the present study was to examine the relationship between improvements in running performance and some of the prominent physiological and metabolic adaptations to endurance exercise training. Twelve male undergraduates agreed to participate in this study (trial group), aged matched physical education students provided a control group. Running performance, assessed as a five km time trial, improved from 19.69 +/- 2.24 to 19.22 +/- 2.03 min in the trial group (P less than 0.01) after training. Maximal oxygen uptake values increased from 56.0 +/- 6.1 to 60.7 +/- 5.4 ml.kg-1.min-1, the running speed equivalent to a blood lactate reference concentration of 4 mmol.l-1 (V-4 mM) increased from 3.79 +/- 0.77 to 4.04 +/- 0.71 m.s-1, and the rate of oxygen consumption at 3.58 m.s-1 (running economy) increased from 43.3 +/- 3.2 to 45.0 +/- 3.4 ml.kg-1.min-1 (P less than 0.01). The control group did not show any significant changes. The improved five km times in the trial group were significantly correlated (r = -0.71; P less than 0.01) with changes in the running economy rather than changes in the VO2 max (r = -0.07; ns), or V-4 mM (r = -0.13; ns) suggesting the increased rate of oxygen utilization reflected a greater oxidative degradation of metabolic substrates together with a slower rate of lactate production.