Alterations In Cycling Mechanics Resulting From Core Fatigue

Abstract

Core stability has been reported to influence lower extremity alignment during functional activities. As a result of the fixed pelvis and feet in relation to the bicycle, lower extremity alignment during cycling is critical. Core fatigue may result in abnormal movement patterns and suboptimal force transmission. Limited research has described the influence of core fatigue on cycling mechanics and pedaling forces. PURPOSE To determine the influence of core fatigue on cycling mechanics and pedaling forces. METHODS Fifteen competitive cyclists (Age: 34.5 ± 9.8 years; Height: 1.77 ± 0.11 m; Mass: 76.3 ± 11.1 kg) participated. Subjects performed two incremental ramp protocols (separated by a minimum of one week) while cycling untethered on a high speed treadmill. The cycling protocol consisted of 1% increments every three minutes at 25.75 kilometers · hour−1, until exhaustion. Kinematic data were collected with a 3D motion analysis system. Pedal forces were collected with custom designed pedals integrated with a 6-degrees-of-freedom load cell. A core fatigue workout to diminish core stability was performed prior to the second test. Four sets of an eight exercise core fatigue circuit were completed as each individual exercise was performed for 40 seconds with a 20-second rest. Separate dependent t-tests were used to compare differences for joint kinematics (hip, knee, ankle, torso) and pedaling forces (effective, anterioposterior, mediolateral) between incline levels of the two tests. An a priori statistical significance was set at p < 0.05. RESULTS Total frontal plane knee motion (15.1 ± 6.0°; 23.3 ± 12.5°) increased following the core fatigue protocol. Total sagittal plane knee motion (69.9 ± 4.9°; 79.3 ± 10.1°) and ankle motion (29.0 ± 8.5°; 43.0 ± 22.9°) increased following the core fatigue protocol. No significant differences were demonstrated for the pedal force data (p > 0.05). CONCLUSIONS Core fatigue resulted in altered cycling mechanics that may increase the risk of injury as the knee joint is exposed to abnormal positioning. Improved core stability endurance may promote greater alignment of the lower extremity when riding for extended time periods as the core is more resistant to fatigue.