EFFECTS OF VARYING CRANK LENGTHS ON EXERCISE VO2 RESPONSE AND LOWER LIMB KINEMATICS

Abstract

Listen

Translate article

1814 The energetic response to exercise is dependent, in part, upon the fiber type composition of the exercising muscle and its recruitment pattern. Altered crank lengths produce a change in the magnitude of force application and, theoretically, movement patterns associated with the cycling movement. We hypothesized that altered crank lengths would produce a change in the pedaling kinematics and recruitment pattern of fiber within the exercised muscles and thereby alter the VO2 response (kinetics and maximum). Seven male cyclists performed incremental and constant load cycle ergometry for measurement of VO2 max and VO2 kinetics, respectively. Each cyclist used his own bicycle which was then attached to a Schwinn Velodyne. The three crank lengths used were 165, 170, and 175 mm. The cadence was individualized. Analysis of videotapes taken during the first and last minute of each exercise bout provided two-dimensional kinematic data on the lower extremities. Results indicated that: (1) there was a higher VO2 max at fatigue for the 170 mm crank arms for 5 of the 7 cyclists (p≤.02); (2) the rapid VO2 kinetics, defined as VO2 at 3 minutes, was significantly higher while cycling with the 170 mm crank arms; (3) crank length did not affect the slow component response (p≥.10); (4) hip joint range of motion was the only kinematic parameter affected by fatigue, increasing with the onset of fatigue; and (5) the range of motion about the knee and hip joints was greater for increasing crank lengths. We conclude that varying the crank length within the range normally used by competitive cyclists affects exercise VO2, lower limb kinematics, and possibly fiber type recruitment patterns.