Author ORCID Identifier

https://orcid.org/0009-0008-5491-0743

Date Available

8-9-2023

Year of Publication

2023

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Education

Department/School/Program

Kinesiology and Health Promotion

First Advisor

Dr. Michael A. Samaan

Second Advisor

Dr. Jody L. Clasey

Abstract

Lower back pain (LBP) is a condition which affects the lumbar portion of the spinal column that can lead to mild to extreme physical pain during seated tasks and has been shown to be prevalent in people who spend long durations sitting particularly in a slumped position or in a position with a large degree of lumbar flexion. LBP can cause regular interruptions in work and in a person’s ability to engage in exercise, and in most extreme cases warrants surgical interventions for clinical treatment. While LBP is prevalent in sedentary populations, it is also quite prevalent in cycling populations where athletes frequently train and perform in a seated position with a large degree of lumbar flexion. Bike alterations, primarily adopting a downward inclination of the anterior tip of the saddle, have been a proposed method to increase anterior pelvic tilt and decrease lumbar flexion, which may contribute to decreased incidence of LBP in cyclists. However, alterations to the fit of a bicycle have the potential to impact performance and cardiometabolic measures, and also have a potential to effect men and women differently, as bicycles were traditionally designed with the male anatomy in mind resulting in differences in the way the sexes traditionally position themselves on bicycles when they ride. Therefore, the objective of this study was to investigate the differences in torso, lumbar and pelvic kinematics differences, cardiometabolic differences (VO2 and HR), and sex-based kinematic differences of the torso, lumbar, and pelvis during a synonymous cycling task on a traditional flat (relative to the horizontal) saddle compared to a saddle angle with an anterior inclination of 12.5 degrees.

We performed kinematic and cardiometabolic assessments in recreational and competitive cyclists without existing chronic LBP during an 8-minute cycling task with a fixed work rate with the flat and inclined saddle angles. A bicycle-based GXTmax (graded exercise test) was conducted in order to establish peak VO2 and peak work rate (in watts) to be used for the kinematic and cardiometabolic assessments. Two subsequent rides conducted at a work rate which corresponded with 80% of elicited peak VO2 were performed during which kinematic or cardiometabolic measures were collected. For kinematic differences motion capture of the torso, pelvis and lower limbs was conducted along with perceived rating of LBP. For cardiometabolic differences VO2 (ml·kg·min-1) and HR (bpm) were collected. For sex-based differences the kinematic data was assessed for each sex and then compared via a 2 way ANOVA analysis.

The results showed that in a population of cyclists without existing chronic LBP no significant differences were exhibited as a result of the two saddle angles in lumbar, trunk or pelvic kinematics, perceived LBP, cardiometabolic measures, or kinematics between sexes. These results only directly pertain to short duration, high intensity cycling, and differences may occur if a different cycling task, particularly one of longer duration, were performed. In conclusion, a saddle inclination of 10-15 degrees does not incur any significant kinematic, cardiometabolic or sex-based differences when compared to a flat saddle angle during short duration, high intensity cycling, but further investigation on kinetics in the lumbar spine and lower limbs as a result of these saddle angles is warranted.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2023.359

Funding Information

KHP (Kinesiology and Health Promotion) Summer graduate funding 2022 & 2023

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