## 4 Discussion
[32] did not show that strength training affects intensity at VT2 and thus does not contribute to improving aerobic endurance, as assessed by ventilation thresholds. According to a study by [PERSON] et al. [7], 12 weeks of resistance training at an intensity of 70-80% of 1 RM increased VO2 max by 4.3%. Unfortunately, this study did not evaluate other physiological parameters whose changes could explain the mechanism leading to the change in VO2 max. Interesting data was reported in another study [14], which showed that 20-week ST training significantly increased blood indicators such as mean red blood cell volume, hematocrit and red blood cell count. The authors [14] suggested that resistance training affects blood morphology by causing an increase in red blood cell-related indices. Incorporating such training into endurance training, according to the authors, may counteract the sports anemia that can occur among endurance trainees. Aerobic capacity depends largely on the efficiency of oxygen transport by the blood, so strength training could have improved aerobic capacity for this reason. In turn, improved neuromuscular efficiency translates into improved running economy (i.e., coordination and stride efficiency), but in our study we did not observe a significant effect of ST at submaximal intensity (VT2), perhaps because the training was relatively short or because of the different form of exercise (cycling not running). In another study [15], the authors reported that ST training significantly improved VO2 max, in a similar manner to high-intensity interval training or prolonged aerobic training. The results of the present study are consistent with previously published studies [6; 7; 8; 9; 33; 30; 31; 32; 33], which showed an increase in maximal oxygen uptake after anaerobic training. However, this effect is not conclusive. [PERSON] et al. [34] showed no improvement in VO2 max in a group training weightlifting at a frequency of 5 times a week for 3 years in combination with endurance training. [PERSON] et al. [35] came to similar conclusions, proving in their study that high-intensity anaerobic training did not improve aerobic capacity as measured by maximal oxygen uptake. The main difference between AIT and ST training is the intensity of the effort. AIT training was aerobic-anaerobic training, while ST training was anaerobic training with maximal or submaximal intensity defined by %1 RM. The difference between AIT and ST training is primarily the external resistance used in the form of free weights or machines, and the technique used to perform the exercises. Load selection in ST training is not based on cardiovascular or respiratory indicators, but on external weight, speed of movement execution, etc. ST is anaerobic training, affecting the nervous and muscular systems by, among other things, activating motor units [3; 4] and increasing the physiological cross-section of muscles [5]. Its effect on endurance capacity is most likely due to improved economy of movement [10; 11; 12; 13; 33; 36]. [PERSON] et al. [9] proved that the use of high-intensity 85%1 RM strength training in cross-country skiers improved running economy by as much as 20.5%. According to the authors, the improvement in endurance occurred as a result of improved economy of movement, and this due to neuromuscular adaptations that improve muscle strength. Similar findings were presented by [PERSON] et al. [11]. [PERSON] et al. [36], in their study, also demonstrated that 8 weeks of strength training improved economy on a bicycle ergometer. Participants were divided into two groups; the first performed training 3x a week with a volume of three series of ten repetitions and an intensity of 50-60% of 1 RM. The second group performed maximal strength training amounting to three series of five repetitions with an intensity of 85% 1 RM. The higher-intensity physical training was followed by a 31% improvement in work economy, while the lower-intensity exercise group improved by only 18%.