Intense Exercise
Damages Muscle Tissue
These microscopic and exercise-induced
injuries include:
1) sarcomere structural damage --
the basic contractile tissue of the muscle
2) Z-line streaming -- damaged
connecting units between the sarcomeres
3) Leakage of intramuscular proteins
into the blood
4) Further damage to subcellular
muscle cell components -- sarcolemma, sarcoplasmic reticulum,
mitochondria
These injuries translate to an
immediate loss of muscle strength and the sensation of
DOMS -- Delayed Onset Muscle Soreness -- 24-48 hours
after.
Two scientists, K. Nosaka and P.M.
Clarkson -- and published in the Medical and Scientific Sports
Exercise Journal in 1995 -- showed there was a 50% decrease in
isometric strength after these types of injuries -- which
persisted for long periods of time even after the pain
subsided.
Also, it is known that the
production of free radicals -- highly reactive substances
known to destroy healthy tissue -- is markedly increased
following exercise.
This leads to an extreme reaction with
the phospholipids making up the cell membranes --
which leaves them unable to hold onto the enzymes inside
the muscle cells responsible for generating strength -- this
was reported by R.B. Armstrong, C.B. Ebbeling, and P.M.
Clarkson in the Medical and Scientific Sports Exercise
Journal in 1989 and 1990, as well as M.P. Miles in the Journal
of Sports Medicine and Physical Fitness in 1994.
Even worse, all cell membranes contain
polyunsaturated acids that are very susceptible to free
radical attack -- this process is called lipid peroxidation.
This increases cell permeability -- not a good thing, causes
an influx of calcium ions and lyosomal -- destructive --
enzymes, and a loss of beneficial intracellular
enzymes.
Scientists Jakeman and Maxwell
investigated the effects of antioxidant vitamin
supplementation on muscle contractile function after it
was damaged by exercise. They found that supplementation
prior to an exercise session may exert a protective effect
against exercise-induced muscle damage.
It's pretty well known that vitamin
concentrations can become depleted due to regular exercise
unless they are supplemented in the diet.
However, the total research dealing with
the effects of antioxidant vitamin supplementation on
exercise-induced lipid peroxidation and tissue damage has been
mixed -- although numerous studies have suggested antioxidant
supplements can be beneficial, there is also data showing no
positive effect of supplementation.
Part of the problem has been theorized to be these studies
have studied only a single vitamin when the effectiveness of
supplementation may depend on the presence of all the
antioxidants.
It is well know that the effects of
damage to a single bout of exercise lasts for several days --
and some studies have shown the markers of muscle damage can
even last several weeks.
Muscle biopsies taken immediately after
exercise showed damage has occurred but that the greatest
damage is observed 3 days or longer after exercise.
H. Kuipers -- as reported in the
International Journal of Sports Medicine in 1994 -- showed
that this exercise induced injury was further complicated --
or made worse -- by metabolism factors -- inadequate
nutrition.
What You Can Do To
Counteract These Effects...
Left alone to it's own devices your body
will attempt to repair this 'damage' created by the simple act
of weight lifting.
Using the constantly circulating "pool"
of amino acids -- or proteins -- in your bloodstream, it will
supply myoblasts -- cells that are precursors to mature muscle
-- with the needed "fuel" to do their job.
These myoblasts are commonly called
"satellite cells" and are found -- normally dormant -- at
the ends of the sarcomeres.
When an injury occurs the damaged
muscles release a growth factor which stimulates the satellite
cells to proliferate, or grow, within 2 days after the
injury. From the 3rd to about the 5th day the satellite cells
migrate to the injury site and fuse together into a myotube --
an immature muscle fiber.
Complete regeneration occurs from 5
days to several weeks after the initial trauma to the
muscle.
How Important Is
Protein?
Several studies have shown nutrition
needs -- protein being by far the most
important -- are dramatically increased as a result of
the body attempting to repair itself.
In 1991 W.J. Evans completed a study at
the USDA Human Research Center on Aging at Tufts Univ in
Boston. His report was titled: "Muscle Damage: Nutritional
Considerations" and was published in the International Journal
of Sports Nutrition.
In speaking of the damage caused by
exercise he stated, "These metabolic alterations may result in
the increased need for dietary protein, particularly at the
beginning of a training program that has a high eccentric
component such as strength training."
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