Relationships between Lower Limb Muscle Characteristics and Force-Velocity Profiles Derived during Sprinting and Jumping

Abstract

Purpose: To identify the relationships between lower limb muscle characteristics and the mechanical variables derived from the vertical (jumping) and horizontal (sprinting) force-velocity-power (FVP) profiles. Methods: Nineteen sub-elite male rugby league players performed a series of squat jumps and linear 30 m sprints to derive the vertical and horizontal FVP profiles, respectively. The theoretical maximal force (F0), velocity (V0) and power (Pmax) were derived from both the vertical (i.e., vF0, vV0 and vPmax) and horizontal (i.e., hF0, hV0 and hPmax) FVP profiles. Vastus lateralis (VL), biceps femoris (BF) long head and gastrocnemius medialis (GM) and lateralis muscle fascicle length, pennation angle and thickness were measured using B-mode ultrasonography. Magnetic resonance (MR) imaging was used to calculate volumes of major lower limb muscles, while proton MR spectroscopy was used to quantify the carnosine content of the GM to estimate muscle fiber typology. Results: Variation in vPmax was best explained by GM muscle fiber typology (i.e., greater estimated proportion of type II fibers) and VL volume (adjusted r2=0.440; P=0.006), while adductor and vastus medialis volume and GM muscle fiber typology explained the most variation in hPmax (adjusted r2=0.634, P=0.032). Rectus femoris and VL volume explained variation in vF0 (r2=0.430; P=0.008), while adductor and vastus medialis volume explained variation in hF0 (r2=0.432; P=0.007). Variation in vV0 and hV0 were best explained by GM muscle fiber typology (adjusted r2=0.580, P<0.001) and GM muscle fiber typology and BF short head volume (adjusted r2 = 0.590, P<0.001), respectively. Conclusion: Muscle fiber typology and muscle volume are strong determinants of maximal muscle power in jumping and sprinting by influencing the velocity- and force-orientated mechanical variables.