The Comparison of Eight Weeks of High-intensity Functional Training with High-intensity Interval Training on Some Factors of Physical Fitness, Time to Exhaustion, and Lactate Levels in Officer Students

High-intensity functional training (HIFT) is an exercise modality that emphasizes functional, multi-joint movements that can be modified to any fitness level and elicit greater muscle recruitment than more traditional exercise. Therefore, this research aims to compare eight weeks of HIFT with high-intensity interval training (HIIT) on some factors of physical fitness, time to exhaustion, and lactate levels in officer students. In this semi-experimental research, 30 officer students with an average age of 20.04 ± 0.84 were randomly divided into 15 HIIT and HIFT groups. All the tests were done before and after the implementation of exercise protocols. Both HIIT (running-based) and HIFT (bodyweight-based functional movements) protocols were performed for 8 weeks, 3 days per week, at the intensity of 85-90% of the maximum heart rate. Basic evaluations included body composition evaluation, fatigue test, muscle strength and power test, and Army physical fitness test. The findings of this research showed that HIFT and HIIT increased respectively aerobic fitness (15.69%, 9.61%), back and leg muscle strength (16.02%, 5.02%), vertical jump (25.31%, 5.14%), push-up (19.61%, 9.39%), sit up (18.24%, 9.83%), time to exhaustion (16.21%, 14.41%) and reduced body fat percentage (18.38%, 12.18%), and lactate levels (22.89%, 14.77%). Also, HIFT was more effective than HIIT in increasing aerobic fitness (P=0.0001), back and leg muscle strength (P=0.0001), leg muscle power (P=0.0001), abdominal and shoulder girdle muscle (P=0.0001) endurance, time to exhaustion (P=0.0001), and reducing body fat percentage (P=0.002). It seems that high-intensity training, especially HIFT can improve several factors of physical fitness at the same time, and it is more suitable for tactical athletes (soldiers, firefighters, etc.) who need high physical fitness to perform their duties.