Effects of high‐intensity interval cycling performed after resistance training on muscle strength and hypertrophy

Abstract

Aim of the study was to investigate whether high-intensity interval cycling performed immediately after resistance training would inhibit muscle strength increase and hypertrophy expected from resistance training per se. Twenty-two young men were assigned into either resistance training (RE; N=11) or resistance training plus high-intensity interval cycling (REC; N=11). Lower body muscle strength and rate of force development (RFD), quadriceps cross-sectional area (CSA) and vastus lateralis muscle architecture, muscle fiber type composition and capillarization, and estimated aerobic capacity were evaluated before and after 8weeks of training (2 times per week). Muscle strength and quadriceps CSA were significantly and similarly increased after both interventions. Fiber CSA increased significantly and similarly after both RE (type I: 13.6±3.7%, type IIA: 17.6±4.4%, type IIX: 23.2±5.7%, P<0.05) and REC (type I: 10.0±2.7%, type IIA: 14.8±4.3% type IIX: 20.8±6.0%, P<0.05). In contrast, RFD decreased and fascicle angle increased (P<0.05) only after REC. Capillary density and estimated aerobic capacity increased (P<0.05) only after REC. These results suggest that high-intensity interval cycling performed after heavy-resistance exercise may not inhibit resistance exercise-induced muscle strength/hypertrophy after 2months of training, while it prompts aerobic capacity and muscle capillarization. The addition of high-intensity cycling after heavy-resistance exercise may decrease RFD partly due to muscle architectural changes.