Mechanical peak power output (PPO) is a determinant of performance in sprint cycling. The purpose of this study was to examine the relationship between PPO and putative physiological determinants of PPO in elite cyclists, and to compare sprint performance between elite sprint and endurance cyclists. Thirty-five elite cyclists (18 endurance; 17 sprint) performed duplicate sprint cycling laboratory tests to establish PPO and its mechanical components. Quadriceps femoris (Q VOL ) and hamstring muscle volume (HAM VOL ) were assessed with MRI, vastus lateralis pennation angle (Pθ VL ) and fascicle length (FL VL ) were determined with ultrasound imaging, and neuromuscular activation of three muscles was assessed using EMG at PPO during sprint cycling. For the whole cohort, there was a wide variability in PPO (range 775-2025 W) with very large, positive, bivariate relationships between PPO and Q VOL (r = .87), HAM VOL (r = .71), and Pθ VL (r = .81).Step-wise multiple regression analysis revealed that 87% of the variability in PPO between cyclists was explained by two variables Q VOL (76%) and Pθ VL (11%). The sprint cyclists had greater PPO (+61%; P < .001 vs endurance), larger Q VOL (P < .001), and BF VOL (P < .001) as well as more pennate vastus lateralis muscles (P < .001). These findings emphasize the importance of quadriceps muscle morphology for sprint cycling events. K E Y W O R D S maximum cadence, maximum power, maximum torque, muscle How to cite this article: Kordi M, Folland J, Goodall S, et al. Mechanical and morphological determinants of peak power output in elite cyclists. Scand J Med Sci Sports.

In addition to muscle size, the maximal evocable force of a muscle (group) appears to be linked to the magnitude of the W' in elite cyclists.