Queensland Police Union Journal

QRPA
changes associated with sarcopenia, and with advancements
in molecular technologies, expect much more light to be
shone on this area in the coming years. However, one of the
most effective treatments in offsetting sarcopenia at this time
is proving to be resistance training. Part 1 of this series will
explore what happens under the skin as you age. Part 2 will
look at the relationships between physical activity, specifically
resistance training and chronic and lifestyle diseases. Part
3 will show you the way forward by offering up a resistance
training program that you can do at home with no equipment
that is suitable for all ages and strength levels.
The good news with our ageing population is that there is an
ever-increasing amount of new research and understanding
about the ageing process. We know what to expect and how
to best offset these effects. There will always be someone
promoting a miracle pill, cream, food, supplement, device, or
even a whole therapy, but the human body is a very complex
organism and understanding one single approach won’t cure
all our problems. If something seems too good to be generally
true, it generally is. Taking control of your health starts with
understanding it, and we’ve included this series of articles to
start that process.
Taking Control
As you age, the following happens under your skin:
• Your neural impulses weaken and decrease in ‘firing’ rate
• Your muscle fibres decrease in size and number
• You lose strength and power
• You lose bone density
• You become a little more unbalanced (only physically of
course)
• You become more likely to develop a chronic disease
You lose strength and power
Strength and power come from two places: motor units and
muscle fibres.
Motor units are responsible for the neural impulse that makes
all your movements happen. They attach to muscle fibre and
‘stimulate’ the fibre to interact with its neighbour to create
a contraction in your muscle. The impulse to stimulate your
muscle fibres comes from your brain, down your spinal cord,
and then onto the muscle. Some muscle contractions can come
directly from your spine and we generally call these ‘reflexes’.
Understand that nerves are a two-way street. Impulses also
travel the other way, to your spinal cord onto your brain. How
else would we know that that foot is ours?
The other factor is your muscle fibres and they can have
different characteristics. They can be thin, have a slower
contraction rate, and be resistant to fatigue. On the contrary,
they can be thick, have a fast contraction rate, but fatigue quite
quickly. A great example of this is the differences in body shape
and size of 100m sprinters and marathon runners. For people
who have a ‘general condition’, their fibres will be a hybrid of
these two types.
The decrease in strength and power as you get older is caused
by a decrease in (a) the strength of the neural impulses, (b) a
decrease in muscle fibre size and number, and (c) decrease in
number of motor units (remember they are attached to muscle
fibres). Research has shown that you can lose up to 30% of
your strength and muscle mass between the ages of 30 to 70.
In early adulthood, skeletal muscle makes up approximately
35-40% of your body weight. So let’s say you weigh 70kg
when you’re 30, approximately 28% of you is muscle. By the
age of 70, you could lose up to 8.4kg of muscle fibre. The very
interesting thing is the more muscle mass you have, the higher
your chances of survival! This is the same for serious burns:
the greater amount of muscle mass you have, the more likely
you are to recover from third degree burns. Greater muscle
mass significantly decreases your chance of developing
chronic lifestyle diseases such as cardiovascular disease or
diabetes and surviving diseases such as cancer.
Another fall-out of a decrease in muscle mass and function is
less stability for your joints. Muscle acts over joints to either
move them or stabilise them. A consequence of weaker
muscles is weaker joints. As you age, there is also a decrease
in blood supply to joints, and an increase in degeneration of
cartilage (spongy ‘stuff’ that sits between bones) and joint fluid.
As you age, there is a decrease in bone density. Bone isn’t a
static, rock-hard substance that never changes. It’s a living,
ever-changing part of your body. In this regard, it could be
compared with coral you find under the sea. During adolescence
and early adulthood, your body lays down as much bone as it
can and then it works at continually renewing it. As you move
through adulthood, the rate at which it can ‘renew’ is slower
than the break-down rate, so you end up with ‘less dense
bones’. The magnitude to which your bone mineral density
decreases is dependent on a few things: genetics, gender, diet
history (specifically calcium intake over your lifespan), and
your muscle mass and strength.
The final, notable consequence of the loss of muscle mass
is a decrease in balance. For young retirees, falling over and
breaking a hip may not be as immediate a concern as it is
for well-seasoned retirees, but understand that becoming
‘unbalanced’ isn’t something you wake up and notice one day.
It’s a gradual process and highly treatable.
Four Pillars to Good Health
Get high quality sleep
Eat a nutritious diet
Be active
Have a caring GP
Queensland Police Union Journal June 2013
79