Comparative Effects of High-Intensity Interval and Functional Training on Performance Outcomes in Adolescent Female Volleyball Players

Participants in the HIIT group engaged in a 12-week resistance-based high intensity interval training program, designed to target both aerobic and anaerobic energy systems. Training sessions were conducted twice per week in addition to the athletes' regular volleyball practice schedule. Each session commenced with a standardized 10-minute warm-up involving low-intensity jogging and dynamic stretching, and concluded with a 5-minute cool-down of light jogging and static stretching to promote recovery. The main training component consisted of short, repeated high intensity bouts (30 s) of multi-modal exercises-including sprint drills, plyometric movements, functional bodyweight resistance exercises, multi-joint strength movements, agility drills, and aerobic conditioning-performed at 85-95% of maximal heart rate (HRmax) \[28,13\]. Each bout was followed by 30 s of active recovery (e.g., walking or light movement).

Participants completed a 12-week high intensity functional training program aimed at developing aerobic capacity, anaerobic power, muscular strength, and agility. Training sessions were performed twice weekly in addition to regular volleyball practices. Each training session followed a standardized structure, beginning with a 10-minute warm-up of light jogging and dynamic mobility exercises, followed by a main training phase consisting of circuit-style functional workouts that combined sprint drills, plyometric exercises, bodyweight resistance movements, multi-joint strength exercises, agility drills, and aerobic activities; each exercise was performed for 30 seconds at maximal effort with no fixed rest between exercises (≤10 seconds transition allowed), and participants completed 4-6 sets per session with 1-2 minutes of rest between sets, while emphasizing maximal movement speed and explosive execution of all repetitions, and concluding with a 5-minute cool-down of low-intensity joggi