RESUMO
Purpose: Discomfort during cycling can be counteracted by adjusting the seat position. However, the influence of changes in cycling position regarding quantitative biomechanical adaptions of the upper body in recreational cyclists is unclear. This study aims to investigate the effects of saddle position and reach distance on upper body kinematics and muscle activation. Methods: Twelve recreational cyclists were investigated in four different sitting positions on an adjustable cycle trainer. Trunk, pelvis, shoulder, elbow and spinal kinematics as well as lower back and elbow extensor activity were analyzed for combinations of normal and shortened reach distance including horizontal and 10° downward inclined saddle positions. Results: An inclined saddle increased activation of elbow extensors by almost 23 ± 8% (p < .01) while a shortened reach distance resulted in a more posterior pelvic tilt of up to 18 ± 2% (p < .01) and less trunk forward lean of 10 ± 9% (p < .01). Shoulder flexion reduced by up to 23 ± 16% (p < .05) while elbow flexion increased by 15 ± 22% (p < .05) with a shortened reach distance. No differences between configurations were found for spinal kinematics and lower back muscle activity. Conclusions: Changing the reach distance showed considerable biomechanical effects on upper body kinematics of the pelvis and trunk rather than on the spine or on lower back muscle activity. For reach distance, most compensation of postural changes of the upper body occurred by changes of shoulder and elbow angles while elbow extensor activation was only altered by saddle downward inclination.
