One of the most important function of the physiological system is the rapid response on stress. The greater is the energy transformation for muscular contraction, which results from aerobic sources, the lesser is dependence on anaerobic mechanisms, which are an important factor in the onset of fatigue (Hepple, 2002; Westerblad, Allen, and Lannergren, 2002). Slower kinetics of oxygen uptake (Vo2), means higher consumption of intramuscular energy phosphates and consequently larger accumulation of their byproducts (Jones and Koppo, 2005).
In this master's thesis we observed and described the adaptations in endurance exercise. During the training period, we have focused on the moment of the first adaptation and on development of changes in time, on daily basis. Those adaptations were observed by determining the second phase of Vo2 kinetics – tau (τ) and with measurements of Vo2 at the absolute constant load. Adaptations were monitored by recording of heart rate (FS) and time, achieved in 2000 m run, which was considered as training.
16 students of the Faculty of Sports Ljubljana, who weren't systematically endurance trained, took part in the study. 9 subjects were selected as experimental group (EXP) and 5 as control group (KON). Each subject performed an initial test (2000 m run), which was used to determine the velocity for each subject for later laboratory treadmill testing (2x 1000 m run ). The subjects were tested for Vo2, at constant velocity. After testing, each individual performed training, (2000 m run, 5 times a week). When we noticed first changes (reduction in heart rate (Hr) or reduction in time in 2000 m run), we again performed the laboratory testing at the same absolute constant velocity. After twenty training units (the last training counted as a field test), the last laboratory test was performed, again at the same absolute constant speed.
We have found, that the first changes are visible after seven training units (even earlier for some subjects). Running 2000 m, 5 times a week, improved the economy of running (reduction in Vo2 compared to the first test by 8.1%) and did not change significantly until the last unit of exercise. Phase 2 τ did not change significantly according to the initial testing, when reduction in Vo2 was observed, and also remained unchanged till the last testing.
We conclude, that mid distance high intensity endurance training in duration of four weeks, improves the economy of running early in training perion (after 7 consecutive training units,
respectively 2 weeks). Improved economy of training is reflected in reduction in Vo2, while no changes in τ were found.
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