John W. Farrell IIIƗ1, Daniel J. BlackwoodƗ1, Brian A. PribbleƗ1, & Rebecca D. Larsonǂ1 1 University of Oklahoma, Norman, OK

Levels of asymmetry have been previously reported during cycling for both force and crank torque. However, these measurements are not currently being used as performance indicators in cycling, leading to a need for the evaluation of asymmetry in power production. Purpose: Therefore, the purpose of the current study was to evaluate the presence of asymmetry in power production during cycling. The effects of exercise intensity and cadence selection on asymmetry were also evaluated. Methods: 21 subjects, ages 18-45, participated in the study. Subjects were assigned to either a Cycling Experience (CE, n=9) or No Cycling Experience (NCE, n=12) group. All subjects performed three graded exercise test (GXT) using a cycle ergometer on three separate visits at three different cadence zones. Cadence zones consisted of: Self Selected (SS), High (100 to 115 rpm), and Low (55 to 70 rpm). Subjects performed the first GXT at the SS cadence while the cadence for the second and third was randomly selected. Power output for each lower limb was assessed using a dual power meter. Power output asymmetry was calculated as the absolute difference between limbs at the initial stage (IS), the stage in which the onset of blood lactate accumulation (OBLA) occurred, and at the stage in which peak power output (PPO) occurred. Two way repeated measures ANOVA was used to determine if significant differences existed between groups and conditions. Results: Significant group by condition interactions were present. There were no significant differences between cadence selection at IS, OBLA, or PPO (P>0.05). However, significant differences were observed between groups at IS (CE 8.70±15.1 vs. NCE 2.87±2.62), OBLA (CE 9.73±14.3 vs NCE 4.31±3.20), and PPO (CE 12.21±14.4 vs. NCE 5.48±3.57). Conclusion: Cadence selection was not significantly related to the level of asymmetry for power output during cycling, but significant differences did exist between the groups for power asymmetry. Cycling performance is closely related to the ability to produce higher power outputs in an efficient manner, so levels of asymmetry in power production could lead to performance decrements. Further research is needed to understand this relationship as well as potential training interventions to reduce levels of asymmetry observed during cycling.

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