Effectiveness of pedalling retraining in reducing bilateral pedal force asymmetries.

Previous studies have been limited to describe asymmetries during pedalling and suggest possible repercussion on performance and/or injury risks. However, few studies have presented strategies to mitigate asymmetries. The purpose of this study was to assess the effectiveness of a pedalling retraining intervention to reduce bilateral pedal force asymmetries. Twenty cyclists were assessed and 10 enrolled in a pedalling retraining method receiving visual and verbal feedback of pedal forces. The asymmetry index was computed for comparison of bilateral peak pedal forces and used during retraining (12 trials at 70% of peak power). Significantly larger asymmetry was observed for asymmetrical cyclists at the first three trials (P < 0.01 and ES = 1.39), which was reduced when post-retraining was compared to measures from symmetrical cyclists (P = 0.69 and ES = 0.18). Cyclists with larger asymmetry (>20%) in bilateral pedal forces reduce their asymmetries using sessions of pedalling retraining and achieve asymmetry indices similar to symmetrical cyclists.

Joint Torques and Patellofemoral Force During Single-Leg Assisted and Unassisted Cycling.

CONTEXT: Unassisted single-leg cycling should be replaced by assisted single-leg cycling, given that this last approach has potential to mimic joint kinetics and kinematics from double-leg cycling. However, there is need to test if assisting devices during pedaling effectively replicate joint forces and torque from double-leg cycling. OBJECTIVES: To compare double-leg, single-leg assisted, and unassisted cycling in terms of lower-limb kinetics and kinematics. DESIGN: Cross-sectional crossover. SETTING: Laboratory. PARTICIPANTS: 14 healthy nonathletes. INTERVENTIONS: Two double-leg cycling trials (240 ± 23 W) and 2 single-leg trials (120 ± 11 W) at 90 rpm were performed for 2 min using a bicycle attached to a cycle trainer. Measurements of pedal force and joint kinematics of participants' right lower limb were performed during double- and single-leg trials. For the single-leg assisted trial, a custom-made adaptor was used to attach 10 kg of weight to the contralateral crank. MAIN OUTCOME MEASURES: Peak hip, knee, and ankle torques (flexors and extensors) along with knee-flexion angle and peak patellofemoral compressive force. RESULTS: Reduced peak hip-extensor torque (10%) and increased peak knee-flexor torque (157%) were observed at the single-leg assisted cycling compared with the double-leg cycling. No differences were found for peak patellofemoral compressive force or knee-flexion angle comparing double-leg with single-leg assisted cycling. However, single-leg unassisted cycling resulted in larger peak patellofemoral compressive force (28%) and lower knee-flexion angle (3%) than double-leg cycling. CONCLUSIONS: These results suggest that although single-leg assisted cycling differs for joint torques, it replicates knee loads from double-leg cycling.

Comparison of kinetics, kinematics, and electromyography during single-leg assisted and unassisted cycling.

To use single-leg cycling training for varying populations, it is important to understand whether a counterweight attached to the contralateral crank during single-leg cycling drills replicates the effects of the opposite leg in the ipsilateral leg. Therefore, we compared single-leg assisted cycling using a counterweight on the contralateral crank for joint kinetics, kinematics, and lower-limb muscle activation. Fourteen healthy nonathletes performed 2 bilateral cycling trials (240 ± 23 W and 90 ± 2 rpm) and 2 single-leg trials (120 ± 11 W and 90 ± 2 rpm) for measurements of pedal force, joint kinematics, and muscle activation of their right lower limb. For 1 single-leg trial, a custom-made adaptor was used to attach 10 kg of weight to the contralateral leg. Total force applied on the pedal, pedal force effectiveness, the mean joint angles and range of motion, mechanical work at the crank, hip, knee, and ankle joints, electromyography, pedaling cadence, and right crank mechanical work were assessed. Biceps femoris (87%), vastus lateralis (15%), rectus femoris (57%), tibialis anterior (57%), and gastrocnemius medialis (12%) activations were larger in the single-leg assisted trial compared with the bilateral trial. Lower total pedal force (17%) and increased index of effectiveness (16%) also indicate mechanical differences in single-leg cycling using a counterweight on the contralateral crank than conventional bilateral cycling. Single-leg assisted training should be used with caution because of potential differences in muscle recruitment and pedaling kinetics compared with bilateral cycling.