Effects of high-intensity interval training and resistance training on physiological parameters and performance of well-trained runners: A randomized controlled trial

This study aimed to verify the effects of 4 weeks of high-intensity interval training (HIIT), heavy (HRT) and explosive (ERT) resistance training on aerobic, anaerobic and neuromuscular parameters and performance of well-trained runners. Twenty-six male athletes were divided into HIIT (n = 10), HRT (n = 7) and ERT (n = 9) groups. Maximal oxygen uptake ($V{O_2}\max $VO2max) and the corresponding velocity ($vV{O_2}\max $vVO2max), anaerobic threshold (AT), running economy (RE), oxygen uptake kinetics, lower-body strength (1RM) and power (CMJ), and the 1500m and 5000m time-trial (TT) were determined. Improvements were observed in $vV{O_2}\max $vVO2max (mean difference (Delta): 2.6%; effect size (ES): 0.63) with HIIT, while AT was incresead in ERT (Delta: 4.3%; ES: 0.73) and HRT (Delta: 6.9%; ES: 0.72) groups. The CMJ performance was increased in ERT (Delta: 13.8%; ES: 1.03), HRT (Delta: 6.9%; ES: 0.55) and HIIT (Delta: 5.4%; ES: 0.34), whereas 1RM increase in HRT (Delta: 38.1%; ES: 1.21) and ERT (Delta: 49.2%; ES: 0.96) groups. HIIT improved the 1500m (Delta: -2.3%; ES: -0.62) and both HRT (Delta: -1.6%; ES: -0.32) and ERT (Delta: -1.7%; ES: -0.31) the 5000m TT. Despite performance adaptations were dependent on the training characteristics, both RT and HIIT model constitute an alternative for training periodization.