& Healing Centre
|
|
|
Muscle Support & Endurance.
Muscle (from Latin musculus, diminutive of mus "mouse") is
the contractile tissue of the body and is derived from the mesodermal layer of
embryonic germ cells. Muscle cells contain contractile filaments that move past
each other and change the size of the cell. They are classified as skeletal,
cardiac, or smooth muscles. Their function is to produce force and cause motion.
Muscles can cause either locomotion of the organism itself or movement of
internal organs. Cardiac and smooth muscle contraction occurs without conscious
thought and is necessary for survival. Examples are the contraction of the heart
and peristalsis which pushes food through the digestive system. Voluntary
contraction of the skeletal muscles is used to move the body and can be finely
controlled. Examples are movements of the eye, or gross movements like the
quadriceps muscle of the thigh. There are two broad types of voluntary muscle
fibers: slow twitch and fast twitch. Slow twitch fibers contract for long
periods of time but with little force while fast twitch fibers contract quickly
and powerfully but fatigue very rapidly.
Endurance (also called sufferance) is the ability for an animal
to exert itself for a long period of time. In humans, it is usually used in
aerobic or anaerobic exercise. The definition of 'long' varies according to the
type of exertion - minutes for high intensity anaerobic exercise, hours or days
for low intensity. Training for endurance can have a negative impact on the
ability to exert strength unless an individual also undertakes resistance
training to counteract this effect.
Athletes train for endurance to compete in 5k and 10k races, half marathons,
marathons, ultra marathons, triathlons, Ironman competitions, Century bike
rides, mountain biking and so on. Non-athletes can train similarly with an
aerobic workout to burn calories and fat. It is known that long distance
training (LDT) for endurance over long periods of time can be helpful to joints
and ligaments as one ages.
Long-term endurance training induces many physiological adaptations both
centrally and peripherally mediated. Central cardiovascular adaptations include
decreased heart rate, increased red blood cell count, increased blood plasma
which reduces blood viscosity and increased cardiac output as well as total
mitochondrial volume in the muscle fibers used in the training (i.e. the thigh
muscles in runners will have more mitochondria than swimmers).
Adaptations of the peripheral include capillarization, that is an increase in
the surface area that both the venous and arterial capillaries supply. This also
allows for increased heat dissipation during strenuous exercise. The muscles
heighten their glycogen and fat storing capabilities in endurance athletes in
order to increase the length in time in which they can perform work. Catabolism
also improves increasing the athletes capacity to use fat and glycogen stores as
an energy source. These metabolic processes are known as glycogenolysis,
glycolysis and lipolysis.
