The influence of ageing and exercise training on the ability in control of force and postural stability

360 Pages·2017·3.71 MB·English

by  Pedro Bezerra

Southern Cross University
ePublications@SCU
Theses
2009
The influence of ageing and exercise training on the
ability in control of force and postural stability in
relation to hamstrings: quadriceps strength ratio
Pedro Bezerra
Southern Cross University
Publication details
Bezerra, P 2009, 'The influence of ageing and exercise training on the ability in control of force and postural stability in relation to
hamstrings: quadriceps strength ratio', PhD thesis, Southern Cross University, Lismore, NSW.
Copyright P Bezerra 2009
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The influence of ageing and exercise training on
the ability in control of force and postural
stability in relation to hamstrings:quadriceps
strength ratio

José Pedro Arieiro Gonçalves Bezerra

Masters of Sport Science

This thesis is presented in fulfilment of the requirements for the degree of
Doctor of Philosophy at Southern Cross University
January 2009
Declaration

I certify that the work presented in this thesis is, to the best of my knowledge and belief,
original, except as acknowledged in the text, and that the material has not been
submitted, either in whole or in part, for a degree at this or any other university.

José Pedro Arieiro Gonçalves Bezerra

20 January 2009
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Abstract

The overall aim of the research was to determine whether the hamstring:quadriceps
strength ratio (HQR) played an important role in postural control and effects of different
training modes on the HQR and its relationship with the ability to control force and
posture in older adults. This thesis reports the outcomes of two related studies. Study
One was a cross-sectional study aiming to determine the age-related changes in the knee
flexor (KF) and knee extensor (KE) isometric muscle strength ratio and the relationship
between the HQR and measured variables in the control of posture in young (YG, 18-
30yrs), middle-aged (MG, 40-50yrs) and older adults (OG, 60-77yrs). Study Two was a
training study for older adults aiming to determine the effects of two training programs,
home-based-exercise (HBE) and electromyostimulation-superimposed-over-voluntary-
contractions (EV), on maximal voluntary contraction (MVC), HQR, muscle steadiness
(ST) and postural control.
Study One indicated that the MVC of the KF and KE decreased at different rates, 34.7%
(~1.4 N.m/year) between MG and OG and 35.6% (~1.5 N.m/year) from YG to OG,
respectively, and HQR was significantly higher in MG than OG (p<0.05). MG showed a
better control of posture than the OG in anterior-posterior and planar directions.
Moderate negative correlations were found between HQR and stabilogram parameters
(r=-0.29, p=0.05). The intervention study indicated that MVC of the KE increased in
both groups (p<0.01), and that of the KF increased in the EV group (p<0.001), however,
the HQR did not change in either group, after six weeks of training. The HBE was
effective in improving KE isometric ST and the EV improved KF isometric ST which
was a novel finding (p<0.05). The stabilogram parameters changed significantly after
training in HBE and EV whilst no differences were found between groups. The training-
induced changes in MVC were not correlated with either ST or postural control. It was
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found that the knee joint stability and the control of force and posture were maintained
until the sixth decade of life. The EV training program was effective in improving
muscle strength and control of force and posture for older adults. However, the
mechanisms responsible for the increased MVC did not appear to be shared by those for
the improved control of force.
These findings suggest that the HQR may be a valid indicator in assessment of postural
control. Further research that focuses on improvement of HQR and its relation to
postural control is needed to validate this implication of HQR. No clear trend on the
fluctuation of force and muscle contraction intensity relationship was observed.
Therefore, to improve the ability in controlling muscle force, more attention should be
given to the skill learning rather than maximum strength. No difference was found in
the pre to post training changes in controlling upright position between the two types of
training examined in this project. Future investigations examining the training effects on
postural control should involve unstable stance positions and perturbed balance. Future
research should also include the recording of EMG data for analysis of the neural
mechanisms responsible for the age-related changes and training effects in control of
force and posture, and increased duration of the training program.
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List of publications related to the thesis

Journal publications (submitted manuscript)

Bezerra, P., Zhou, S., Crowley, Z., Brooks, L., and Hooper, A. (2008). Effects of
unilateral EMS superimposed on voluntary training on strength and CSA.
Muscle & Nerve. (accepted for publication)
Bezerra, P., Zhou, S., Crowley, Z., Davie, A., and Baglin, R. (2008). Age-related
change in quadriceps to hamstring strength ratio and its relation to postural
stability. Gait & Posture.
Bezerra, P., Zhou, S., Crowley, Z., Davie, A., and Baglin, R. (2008). Effects of
electromyostimulation training and home-based exercise on hamstrings and
quadriceps muscle strength and steadiness in older adults. Journal of
Gerontology: BIOLOGICAL SCIENCES.

Conference publications

Bezerra, P., Zhou, S., Davie, A., Fuller, H. and Hooper, A. (2006). MRI analysis for
thigh muscle and fat composition changes in strength training. Conference
proceedings of the ASICS Conference of Science and Medicine in Sport held in
Fiji.
Bezerra, P., Zhou, S., Davie, A. and Crowley, Z. (2007). Repeated trials and age-
related effects on performance in stabilogram, muscle steadiness and muscle
strength tests. Conference proceedings of the Australian Conference of Science
and Medicine in Sport held in Adelaide.
Bezerra, P., Zhou, S., Crowley, Z. and Baglin, R. (2008). Age-related changes in
quadriceps to hamstrings strength ratio and its relation to postural stability.
Conference proceedings of the 3rd Australian Association for Exercise and
Sports Science conference held in Melbourne.
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Bezerra, P., Zhou, S., Crowley, Z. and Baglin, R. (2008). Efects of
electromyostimulation training and home-based exercise on hamstring and
quadriceps muscle strength and steadiness in older adults. Conference
proceedings of the International Convention on Science, Education and
Medicine in Sport, Guangzhou, China.
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For Gabi
For Aussie

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Acknowledgments

I could not have completed this thesis without the generous help of family, friends, and
colleagues.
My thanks go to …
I would like to thank, first and foremost, my advisor, Associate Professor Shi Zhou, for
his guidance and support throughout my graduate course career, from the initial stages
to the final draft of this thesis and for his brilliant knowledge;
Associate Professor Allan Davie for his advice, encouragement and positive point of
view even positives were hard to find;
My patient and loving Gabi, who has been a great source of strength and encouragement
all through this work;
My family for the support they have provided me through my entire life and for never
losing faith in me during this three year project;
Zac Crowley deserves special mention as an outstanding friend and colleague
throughout my time at Southern Cross University;
Robert Baglin for his logical thoughts and magic fingers save me uncountable hours of
data analysis;
Roz Beavers for her positive encouragement, “the only way is up”. I wish I can help
you on your PhD track;
Carol Laskey for continuing to provide a rich and friendly environment in which to
work;
Jim, Cindy, and Amy Crowley for their hospitality and support during the process of
writing this thesis by giving me important feedback. To have had a family in Australia
gave me additional motivation;
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Some friends, like Nam Nguyen and Vu Nguyen, for being tolerant enough to live with
me for two years and good enough not to throw me overboard;
Yungsheng Chen for the long chats and support in the last months of this project;
The subjects for the enthusiastic participation in both testing and training sessions;
All those who in one way or another helped me;
Pierpaolo Lucchetta for believing in my project and providing important
instrumentation for the research;
The last but not the least, I recognize that this research would not have been possible
without the financial assistance of Fundacao para a Ciencia e Tecnologia and I express
my gratitude to that Portuguese government department.
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