Features of the decrease in running speed in students of the faculties of physical education and sports as the distances increase from sprint to medium: an observational study with a physiological rationale

Background and purpose Running at different distances involves changes in energy systems and biomechanical demands, which affect running speed. There is a need for a more detailed study of the relationship between physiological and biomechanical factors in physical education and sports students.  Aim to analyze the fluctuations and tendency to decrease running speed at distances of 100 m, 200 m, 400 m and 800 m, as well as the physiological and biomechanical substantiation of the characteristics of this tendency in third-year students of the Faculty of Physical Education and Sports. Material and methods The participants were 25 students (average height 174.84 cm, weight 75.92 kg, BMI 22.90) attending the Athletics 1 course and regularly engaged in training. Four running distances (100 m, 200 m, 400 m, 800 m) were tested by measuring times and calculating average speeds. The runs were performed under standardized conditions with maximal effort. Data were statistically analyzed using means, variability measures, and Pearson correlation (p < 0.05). Results The highest average speed was recorded in the 100 m (7.76 ± 0.57 m/s; mean time 12.95 ± 1.00 s), followed by a slight decrease in the 200 m (7.19 ± 0.80 m/s), reflecting the predominance of the anaerobic alactic energy system. A more pronounced reduction was observed at 400 m (6.18 ± 0.61 m/s) and further at 800 m (4.59 ± 0.48 m/s), indicating a metabolic shift towards anaerobic lactic and aerobic pathways, accompanied by fatigue and lactate accumulation.  The overal decrease in average speed at a distance of 100-800 m was 40.86%. Statistically significant positive correlations were found between performances in all distances (p < 0.05), with the strongest correlation between 100 m and 200 m (r = 0.826; p = 0.000), followed by 100 m and 400 m (r = 0.739; p = 0.000), 400 m and 800 m (r = 0.719; p = 0.000), 200 m and 400 m (r = 0.665; p = 0.000), 100 m and 800 m (r = 0.642; p = 0.001), and 200 m and 800 m (r = 0.573; p = 0.003. Conclusion The students demonstrated well-developed explosive and short-term running abilities but limited aerobic endurance and speed maintenance on longer distances.