Student Travel Reports

I would like to take this opportunity to thank the International Society of Biomechanics council for their support in providing research funding through the Matching Dissertation grant. The funding I received was a major influence in the direction my PhD took, as it allowed me to develop gait analysis equipment that was neither cheap nor commercially available.



The focus of my research is to examine dynamic stability of the upper body during walking. In my PhD research to date, I have used commercially available accelerometers and data logging products which have provided valuable insight as to how the postural system organises motion of the head and trunk during walking^1,2,3. However, further insight could be gained with a multi-accelerometer system that was fully telemetered. Therefore, the majority of ISB funding contributed towards the development of a new accelerometer-based gait analysis system ($3750.00) and consumables (sports tape: $39.60, batteries $132.00). In conjunction with the Centre for Wireless Technology and Applications, Griffith University, a system was developed that consisted of 4 tri-axial wireless accelerometers that transmitted data to a PC via a Bluetooth protocol. The wireless and lightweight nature of this system facilitates unencumbered movement of the subject and allows data collection to be performed outside of a laboratory setting. For the purpose of examining stability during walking, accelerometers were attached to the head, upper trunk, lower trunk, and shank.



A research proposal was included in my funding application which outlined three research questions to be addressed. They were as follows:



1) What is the reliability of the new accelerometer system as a gait analysis tool?

A reliability study was performed which used the coefficient of multiple determination to determine the repeatability of testing methods and accelerations collected from different levels of the body. The results of this study indicated the reliability of the system was good, and had the potential to be applied to a gait analysis setting. This study has recently been published in the Journal of Biomechanics⁴.



2) How are gait related oscillations attenuated throughout the body?

With the new multi-accelerometer system it was possible to examine two segments of the upper body: the neck segment, and the trunk segment. The attenuation characteristics throughout the upper body were quantified over a range of walking speeds. Overall the findings of this study suggested that the trunk segment plays a critical role in regulating gait-related oscillations in all directions. Only accelerations in the direction of travel at preferred and fast speeds required additional control from the neck segment in order to enhance head stability during walking. This study has recently been published in Experimental Brain Research⁵.



3) To what extent does the neuromuscular system influence dynamics stability?

A study was performed which examined how inducing fatigue of the lumbar and cervical erector spinae affected the ability to maintain head stability during walking. Overall, the results of this study suggest that erector spinae fatigue differentially altered upper body segmental attenuation during walking according to the level of the upper body that was fatigued, and the direction that oscillations were attenuated. A compensatory postural response was not only elicited in the sagittal plane where greater segmental attenuation occurred, but also in the frontal plane where greater segmental gain occurred. This study is currently under review³.



Once again I would like to thank the International Society of Biomechanics for their generous funding through the Matching Dissertation grant.







Justin Kavanagh



School of Physiotherapy and Exercise Science

Griffith University

PMB 50 Gold Coast Mail Centre

Queensland 9726 Australia

Tel: (07) 5552 8057 International: (+61 7 5552 8057)

Fax: (07) 5552 8674 International: (+61 7 5552 8674)







References



¹ Kavanagh, J.J., Barrett, R.S., and Morrison, S. (2004). Upper body accelerations during walking in healthy young and elderly men. Gait and Posture. 20:291-298.



² Kavanagh, J.J., Morrison, S., and Barrett, R.S. (2005). Coordination of head and trunk accelerations during walking. European Journal of Applied Physiology. 94(4): 468-475.



³ Kavanagh, J.J., Barrett, R.S., and Morrison, S. (2005). Age-related differences in head and trunk coordination during walking. Human Movement Science. 24(4): 574-587.



⁴ Kavanagh, J.J., Morrison, S., James, D., Barrett, R. (2006). Reliability of segmental accelerations measured using a new wireless gait analysis system. Journal of Biomechanics. In press.



⁵ Kavanagh, J.J., Barrett, R.S., and Morrison, S. (2006). The role of the neck and trunk in facilitating head stability during walking. Experimental Brain Research. In press.



⁶ Kavanagh, J.J., Morrison, S., and Barrett, R.S. The effects of cervical and lumbar erector spinae fatigue on attenuation of gait-related upper body accelerations. Journal of Applied Physiology. In review.