Muscle recruitment patterns and saddle pressure indexes with alterations in effective seat tube angle

Abstract

Alteration of the effective seat tube angle (ESTA) may affect muscle activation patterns of the lower limbs in cycling. There is conflicting evidence due to inadequate kinematic controls in previous studies. The primary aim of this study was to determine the muscle activity of seven lower limb muscles during alterations of the ESTA by altering the position of both the handlebars and saddle forwards or backwards by 3 ​cm while ensuring controlled kinematics. Secondly, to determine the effect on the saddle pressure indexes. Ten participants performed two 5 ​min electromyography (EMG) trials at 70% of peak power output (PPO) for three consecutive visits. There was a significant increase in muscle activity in the biceps femoris, gluteus maximus, and medial gastrocnemius with reductions in ESTA while a significant increase in tibialis anterior with increases in ESTA was observed. Saddle pressure indices demonstrated a significant change in frontal versus back pressure as well as mean pubic pressure with changes in ESTA. Alteration in the ESTA affects muscle activity in some, but not all of the lower limb muscles. Further research needs to be conducted to adequately understand the mechanism behind the differences in muscle activation.

Keywords

EMG / Muscle recruitment / Seat tube angle / Pressure mapping

Authors’ contributions

This original study proposal was drafted by Wendy Holliday and Jeroen Swart. The data was collected and analysed by Reece McDonald with the assistance of Wendy Holliday and Jeroen Swart. This manuscript was written by Reece McDonald with the valued guidance and input of Wendy Holliday and Jeroen Swart.

Ethical approval statement

A Physical Activity Readiness Questionnaire (PAR-Q) training history questionnaire and an informed consent form were completed and signed by each participant prior to partaking in the study. Each participant was informed of the potential risks and protocol prior to each visit. The study was approved by the Research and Ethics Committee of the Faculty of Health Sciences, University of Cape Town and conformed to the World Medical Association Declaration of Helsinki and the American College of Sports Medicine (ACSM) Guidelines for the use of Human Subjects.

Conflict of interest

The authors have no conflict of interest to declare.

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Thanks are given to all the cyclists who participated in this study.