The current preoccupation with cardiovascular (or aerobic) conditioning in
promoting health and fitness may be complicated by the implications of
current research into the dangers of free radicals.
The potentially valuable role played by cardiovascular ('aerobic') exercise
in preventing or treating heart disease or offering anti-ageing benefits is
well known to anyone who reads the scientific or popular literature.
Aerobics classes and distance/endurance activities are promoted by the
medical profession and a hugely successful fitness market as a panacea for
virtually all ills.
The listed benefits of aerobic exercise include improvements in VO2 max,
cardiac function, general circulation, reduced levels of 'harmful'
cholesterol, resting metabolic rate (and its effect on bodyfat loss), muscle
function, mood state and several other factors.
The importance of relying heavily on aerobic metabolism instead of anaerobic
activity is stressed frequently, because the latter is not believed to offer
comparable general physiological benefits. 'Anaerobic' training seems to be
acceptable for muscle building, a modicum of local muscle endurance, power
production, speed training and connective tissue, but not really for overall
cardiac or circulatory health (even though more research is questioning these
older dogma).
Recently other research is pointing out the probable serious dangers posed by
free radicals, a type of voracious biochemical structure that is produced
prolifically during aerobic metabolism. These powerful oxidising elements
are reputed to migrate throughout the body and act as triggers or modifying
agents which cause ageing of tissue, some types of cancer and other
miscellaneous diseases. We are advised to consume sufficient quantities of
anti-oxidants in our food in order to combat the harmful side-effects posed
by these apparently vicious by-products of aerobic metabolism. Thus, the
health food market is now flooded with reputed anti-oxidants such as
beta-carotene, selenium, Vitamin E, Vitamin C and various oils.
Does the proliferation of these apparently harmful oxidants or free radicals
in our bloodstream by aerobic processes not then seem to suggest another
solution to the problem, namely, a major reduction in the amount of aerobic
exercise currently being advocated by almost everyone in the health business?
In other words, less aerobic training, fewer free radicals and less damaging
oxidation to age and disease our bodies!
Would a stronger move to anaerobic exercise, such as heavier weight training,
sprinting and intensive intervals then not be the appropriate advice in the
light of this current research into free radicals and tissue change?
Remember, of course, that many of our maintenance daily activities such as
sitting, sleeping and other sedentary tasks depend primarily on aerobic
metabolism. Some regeneration of partially depleted ATP and CP stores also
takes place under aerobic conditions, so it is impossible to live under
entirely anaerobic conditions.
Explain this apparent paradox on the basis of relevant research references
and any other information which you consider to be relevant to resolve the
issue.
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PP84: FRACTALS PHYSIOLOGY PARADOX
Current proposals that fractal geometry enables us to understand and
manipulate many aspects of physiology (such as circulatory, respiratory,
cardiac and nervous phenomena), however attractive and innovative they may
appear, may be over-simplistic and as equally limited as other theories and
methods which they are intended to replace.
Background
The concept of fractals was devised by Benoit Mandelbrot in 1975, his book
'Fractals: Form, Chance and Dimension' 1977) becoming a modern classic
soon after appearing on the bookshelves. Mandelbrot coined the word
'fractal'
because he assigned to each of the self-similar curves in systems like tree
branches and roots a fractional dimension greater than its topological
dimension. Fractals refer to any geometric pattern (other than Euclidean
lines,
planes and surfaces) which display the remarkable property that no matter how
closely you analyse, subdivide or magnify it, any given segment of the
pattern
always looks the same. This property is known as 'self-similarity'.
Thus, if we look at a large branch of a tree with many smaller branches
extending out from the main stem, we will notice that the selfsame pattern of
branching continues right down to the tiny branching displayed by the veins
in
the leaves or the roots supporting the trunk. Applications in physiology
draw
the parallel that the dendrites of neurons, the veins and capillaries of the
circulatory system and the network of airways associated with the lungs all
display the same sort of branching within branching, like the old 'boxes
within
boxes' game known since ancient times.
Ary Goldberger of Harvard Medical School and colleagues have been
especially active in modelling various physiological systems in terms of
fractal
geometry (Goldberger A & West B Yale J of Biology & Med 1987, 1: 421-
435; West B & Goldberger A American Scientist 1987, 75 (4):
354- 365;
Goldberger A et al Experientia 1988, 44: 983-987), especially insofar as
fractal theory is related to so-called chaotic processes in biology, which
have
been shown to innovatively explain sudden heart death, cell division, sudden
changes in hormonal levels, apparently erratic nervous events and other non-
linear processes in many life forms. Other work and theories by scientists
such
as Ilya Prigogine ('Dissipative Structures'), David Bohm ('Implicate Order')
and
Rene Thom ('Catastrophe Theory') also relate to the same type of non-linear
or
indeterministic processes.
Besides stimulating the development of a new paradigm in the biological
sciences, many popularisations of the applications of chaos, catastrophe,
quantum, relativistic, fuzzy logic and other latter day physical theories and
models have even reached the general public in the form of books such as 'The
Tao of Physics', 'The Dancing Wu-Li Masters', 'Fuzzy Thinking', 'The Search
for Schrödinger's Cat', 'Order out of Chaos' and 'Chaos: Making a New
Science'.
Chaos and other non-linear theories explain that highly deterministic and
linear
processes are very fragile in maintaining stability over a wide range of
conditions, whereas chaotic systems can function effectively over a wide
range
of different conditions, thereby offering adaptability and flexibility. This
plasticity of function enables these systems to cope with the
unpredictability
and variability of the environment, bestowing dynamic adaptability instead of
a
more vulnerable precise homeostasis.
In this context, the psychiatrist, A Mandel reflected: "Is it possible that
mathematical pathology, i.e. chaos, is health? And that mathematical
health,
which is the predictability and differentiability of this kind of a
structure, is
disease?". Furthermore, he added: "When you reach an equilibrium in
biology,
you're dead!" (Gleick J 'Chaos: Making a New Science' 1987).
More Applications
Dorko has suggested that fractal models of physiological systems be used to
take conventional physical therapy further. In doing so, he applies the
categorisation that the nervous system and the skin are fractal or non-linear
in
character, whereas muscles, bones, ligaments and tendons are linear or non-
fractal. This classification leads him to suggest that linear tissues
display a
highly predictable response to irritation, stimulation or injury.
Dysfunction or
pain arising from these structures, therefore, is easily interpreted. On the
other
hand, disorders affecting fractal systems like the nerves and skin are often
idiosyncratic and difficult to analyse and control. This leads him to
propose a
fractal model and therapeutic approach which may overcome some of the
problems not adequately explained by what might be termed the classical
mechanistic model of physical therapy.
Further along the Branches
If we travel further along the branches of fractalism in biology, we reach
the
stage that Alice reached when she tried to look beyond the Looking-Glass:
what happens when we reach the level of magnification or subdivision where
the apparent boundaries suddenly become living cells and components of cells?
That is precisely the question posed by the ancients when the atom was
defined
as that smallest indivisible particle which remains when you continue to
subdivide matter indefinitely. This is the same issue which is captivating
the
attention of many of the world's greatest physicists who long ago progressed
to
a level of scrutiny and imagination that postulated the existence of quarks
as
even tinier constituents of matter.
At some stage of subdivision of the dendritic, alveolar or dermal branches we
have to reach the point where the boundary must be seen as cell membranes,
myelin sheaths, the constituents of the cells and ultimately the molecular
building blocks of the cellular material, RNA, DNA and so forth. Does
fractal
theory then imply that all physiological fractal systems remain fractal even
to
this level of subdivision - or is there a breakdown of fractalism at a
certain
stage? Can we then deduce that the molecular structures comprising many
physiological systems are really fractal? Maybe we can view them as being
non-linear in structure and function, but does this entitle us to regard them
as
fractal? Is fractalism (fractality?) identical to non-linearity in such
contexts?
Are we justified in classifying the musculotendinous and ligamentous systems
as linear, when microscopy has shown very clearly that their fine structure
is
actually helical, similar to that of DNA? At an even more microscopic level,
many proteins also exhibit helical structuring. Indeed a major question
concerns the reasons why and how newly made inactive and loosely coiled
proteins wind themselves into specifically shaped biologically active balls
able
to perform their particular tasks in a living cell (Richards F The Protein
Folding Problem Scientific American Jan 1991). While we are at
this level
of
conjecturing, we have to ask if we are justified in referring to helically
twisted,
dynamically strung sequences of amino acids as linear systems? Or would
Mandelbrot be more satisfied to call these structures fractal?
Are we justified in focusing on the fractal nature of neurons and neglecting
the
interactive role of the surrounding neuroglial cells, which are far more
numerous than the neurons? Traditionally the neuroglia are often thought of
only as supportive tissue which play some role in neural nutrition and
stability,
but for many years have been known to exhibit slowly varying electrical
potentials.
What are we to make of the electrostatic, electrodynamic and electrochemical
processes associated with these biologically alive chemical aggregates? Do
we
consider these forces and processes to be fractal or linear? What are we to
make of the 'life force' associated with these biochemically wedded units?
Would it be better to think of them as bits of information or packages of
entropy, so that we should rather look at this microscopic melee in terms of
mathematical non-linearities rather than structural fractals? After all,
matter
and energy have, since the days of Einstein, been regarded as two faces of
the
same coin.
Now this is tending to sound very abstruse and mathematical with very little
attachment to the 'real' world of anatomy and therapy - but this foray into
the
microscopic world had to be done to examine whether or not the notion of
fractality may break down somewhere en route to explaining or controlling
'reality' or the apparently macroscopic problems of medicine.
Fractal Structure or Fractal Function?
Fractal theory has been used successfully to describe and analyse physical
structures such as nervous, venous or river systems, as well as the outputs
or
functions of these and other structures. This brings us to the very
fundamental
issue of the differences and relationship between fractal structure and
fractal
function.
After all, Dorko and others imply that non-linear, non-deterministic, fractal
output is of necessity produced by fractal or non-linear structures. Are we
justified in making this deduction? Is it not possible for a linear
structure to
produce a non-linear or fractal output, or for a non-linear or fractal
structure to
produce a linear output? To enhance adaptability and survival, might
biological systems not sequentially flip-flop between fractal and linear
function
or simultaneously exhibit linearity and fractal behaviour (these
possibilities are
allowed for in certain books on fractal mathematics).
Is Alice looking from one side of the looking glass at her reflection and her
reflection is simultaneously looking at Alice from its side of the mirror,
so that
part of the answer lies in understanding the nature of the mirror and another
part lies in understanding the nature of the viewer? How self-similar is a
mathematical model to the structure or function it is attempting to describe?
How much is the fractal map the territory?
In trying to apply theories of fractal mathematics and non-linear dynamics to
physiological systems, are we not raising more questions that may be
misleading us almost as much as the classical models that have served us so
far? Are these borrowings from 'modern' physics not simply a matter of
describing the same phenomena in a different language, rather than offering a
method of real advancement of knowledge and application? Or do they really
add a valuable dimension to what we have been using blindly for many
decades? After all, Mandelbrot himself acknowledged that his system
described better than it explained.
Over to You
Comment on the questions or issues posed in the above P&P, drawing on
relevant publications or the philosopher within you.
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PP 86 : NEUTRAL POSTURE PARADOX
The concept of neutral pelvic tilt and other forms of structural
or functional neutrality may constitute a problematic and misleading
oversimplification in applied sports and rehabilitation science.
The concept of neutral pelvic tilt is applied ubiquitously in the world of
sports science and rehabilitation, as if it is a universal constant
like the velocity of light. Very little comment is made about how this
neutrality is defined and what its scope of validity is.
If we define neutral pelvic tilt in the standing anatomical position,
then gravity is acting longitudinally along the vertical axis of the
erect body. Suppose we now wish to discuss some activity executed in any
other positions such as supine, prone or side-lying. Do we now
compare any movements or changes relative to the definition of
neutrality decided upon in the standing posture?
Does the pull of the gravitational field not determine a new neutral
position for each new posture? Or can one still apply the original
defintion of neutrality without altering our interpretation of
muscular, neuromuscular or kinaesthetic action? What about
neutrality in the inverted position?
We often hear the advice that one should generally attempt to
maintain neutral pelvic tilt during lifting, squatting, walking and
other common daily activities with or without added loading.
However, we are well aware of the fact that there is a specific
'lumbar-pelvic rhythm' for all activities which involve leaning and
lifting (actually other joints are also involved, but let's accept Calliett's
terminology for the meantime).
In other words, it would appear that the position of neutrality is situation
specific and depends on factors such as added load and whether one is in a
static or dynamic situation. After all, how does one define neutrality
during running, when the pelvis is being rotated and tilted in several
directions
simultaneously?
Do we have to then distinguish between neutrality under static and
dynamic conditions, as well as under conditions in which the
longitudinal axis of the body is no longer in the direction of the
gravitational vector?
This apparent paradox concerning neutrality of pelvic disposition
would also have further implications for any advice to utilise
posterior or anterior pelvic tilt to carry out any specific task,
because this advice may just be another way of advising one to return
the pelvis to its so-called 'neutral' position!
Comment on this apparent paradox, quoting any references or offering
a logical analysis of the propositions stated above.
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