There are many interdependent factors which influence the physical performance. Generally, the following factors are considered to be essential: energy output of aerobic and anaerobic processes, neuromuscular function including strength and technique and psychologi-cal factors as suggested by Saltin and Åbtrand (1967). Ikai (1970) presented the following formula showing the relation between physical performance and physical resources: Physical performance = Skill f (physical resources). The similar relation can be approached from the mechanical point of view. Fenn (1930)has found a high value of mechanical eftibiency of about 23% in runners performing at top speed. Efficiency is a ratio of the work done to the amount of energy used. This efficiency is modified by skill based on the neuromuscular function. The present study was intended to examine experimentally the relation between physical performance and physical resources in 5000m running. The mean speed is one of the best indices of the physical performance in endurance events. As the total energy for 5000m running depends by almost 80% upon the oxygen uptake during running, the maximal oxygen uptake is a direct index of three physical resources. Therefore, the maximal oxygen uptake of the runners was studied in relation to the mean speed of 5000m running.