Symposium of Student Scholars

Effects of Plyometric-Based and Cycle-Based High-Intensity Interval Training on Muscle Size, Quality, and Function

Muscular adaptations for the knee extensors (KEs) and plantar flexors (PFs) may be unique after cycling and weight-bearing high-intensity interval training (HIIT). The purpose of this study was to compare the effects of CY and WB HIIT on muscle strength, explosiveness, size, and quality. Thirty females (18-28 yrs) were assigned to an 8-week HIIT intervention that involved either cycle-based (CY; n=15) or weight-bearing, plyometric training (WB; n=15). Before and after the interventions, isokinetic peak torque (strength) and time to peak torque (explosiveness) were assessed for the KEs and PFs. Ultrasound analysis determined muscle size and quality (fat/connective tissue infiltration) for the same muscle groups. Muscle size remained unchanged for both muscle groups regardless of intervention type (p>0.05). Muscle quality improved for both the KE (-10.3%; p=0.001) and PFs, but the PFs demonstrated a greater improvement after WB (-9.2%; p0.05). The greater improvement in muscle quality for the PFs after WB is likely due to the greater demands for this muscle group during plyometric movements. Nonetheless, despite the high-intensity aerobic effort, the lack of muscle loading even for the plyometric-based intervention did not prove beneficial for muscle size or function.