Purpose. The aim of this study was to investigate the influence of 8-week-long interval training (targeting glycolytic capacity) on selected markers of physical fitness in amateur long-distance runners. Methods. The study involved 17 amateur long-distance runners randomly divided into an experimental (n = 8) and control (n = 9) group. The control group performed three or four continuous training sessions per week whereas the experimental group performed two interval running training sessions and one continuous running training session. A graded treadmill exercise test and the 12-min Cooper test were performed pre- and post-training. Results. O2max and the rate of recovery increased in the experimental group. Relative oxygen uptake, minute ventilation, and heart rate speed decreased in low- (6 km/h) and medium-intensity (12 km/h) running. Conclusions. Both training modalities showed similar results. However, the significant differences in training volume (4-8 min interval training vs. 40-150 min continuous training) indicates that the modalities targeting glycolytic capacity may be more efficient for amateur runners prepare for long-distance events.