Physiology of Exercise and Physical attach to the periosteum connective

Activity (Hand Out) tissue that surrounds bones. Being

Instructor: Raxu Nil B. Peñaranda anchored to two bones allows movement
of the skeleton when the muscle contracts.
Physiology of Exercise A different type of muscle surrounds many
organs, and the epimysium connects to
Physiology is the academic study of the
other connective tissues to produces
various processes, systems, and functions
forces on the organs, controlling
of the human body as influenced by the
performance of physical activity. everything from circulation to food
processing.
The Physiology of Exercise is a broad
concept that addresses the central issue Function of Muscle
as to how the body adapts itself to the Whether it is the largest muscle in your
demands of physical activity. body or the tiny muscle controlling the
movement of your eye, every muscle
Structure and Function of the functions in a similar manner.
Exercising Muscle
A signal is sent from the brain along a
Muscle Definition bundle of nerves. The electronic and
A muscle is a group of muscle tissues chemical message is passed quickly from
which contract together to produce a nerve cell to nerve cell and finally arrives
force. A muscle uses ATP (adenosine at the motor end plate. This interface
triphosphate) to contract and shorten, between the muscle and nerve cells
producing a force on the objects it is releases a chemical signal, acetylcholine,
connected to. which tells the muscle fiber to contract.
This message is distributed to all the cells
Structure of Muscle in the fiber connected to the nerve.
A muscle consists of many muscle tissues
bundled together and surrounded by This signal causes the myosin proteins to
epimysium; a tough connective tissue grab onto the actin filaments around them.
similar to cartilage. These are the purple proteins In Image 2.
Myosin uses ATP as an energy source to
The Epimysium crawl along the green filament, actin.
surrounds bundles of nerve cells that run As you can see, the many small heads of
in long fibers, called fascicles. These the myosin fibers crawling along the
fascicles are surrounded by their own actin filaments effectively shortens the
protective layer, the perimysium. This length of each muscle cell. The cells,
layer allows nerves and blood to flow to which are connected end-to-end in a long
the individual fibers. Each fiber is then fiber, contract at the same time and
wrapped in an endomysium, another shorten the whole fiber. When a signal is
protective layer. As seen in Image 1, a sent to an entire muscle or group of
muscle is arranged in a basic pattern of muscles, the resulting contraction results
bundled fibers separated by protective in movement or force being applied.
layers.
A muscle can be used in many different
These layers and bundles allow different ways throughout the body. A certain
parts of a muscle to contract differently. muscle might contract rarely with a lot of
The protective layer surrounding each force, whereas a different muscle will
bundle allows the different bundles to slide contract continually with minimal force.
past one another as they contract. The Animals have developed a plethora of
epimysium connects to tendons, which
uses for the forces a muscle can create. more protein than is lost). Ingesting more
Muscles have evolved for flying, protein than needed, however, does not
swimming, and running. They have also lead to increased protein synthesis over a
evolved to be pumps used in the certain level and too much protein can
circulatory and digestive systems. The result in dehydration, loss of urinary
heart is a specialized muscle, which is calcium, and stress on the kidneys and
liver. Recommended protein intake is .8–2
used exclusively for pumping blood
gm protein/kg body weight per day or 12–
throughout the body. These different
20% of total energy intake.
types of muscle will be discussed.
FAT
Fuel Sources During Exercise
Fat is the major fuel for light-intensity
At rest and during normal activities, fats to moderate-intensity exercise, such as
contribute 80–90% of our energy; jogging, hiking, dance, cycling, and
carbohydrates provide 5–18% and recreational swimming. Half of the energy
protein 2–5%. During exercise there are for these activities comes from the
four major endogenous sources of aerobic (using oxygen) breakdown of
energy: muscle carbohydrate stores muscle sugar stores (glycogen) and the
other half comes from circulating blood
• glycogen sugar and fatty acids. It is recommended
• blood sugar that athletes consume 20–30% of
• blood fatty acids calories as fat. These fats should include
• intramuscular triacylglycerols. the ―good fats, such as the essential fatty
acids EPA (eicosapentaenoic acid),
The extent to which these substrates DHA (docosahexaenoic acid) that are
contribute energy for exercise depends on found in fish, flax, avocados, and olive oil
the intensity and duration of exercise, the as well as typical meat/dairy fats. Intake
level of exercise training, the initial muscle of trans fatty acids (from partially
glycogen levels, and supplementation with hydrogenated oils) should be avoided
carbohydrates during exercise. entirely and saturated fats should be
limited but not completely restricted.
Protein
Carbohydrates
Protein can be used by the body for fuel
or for anabolic processes. Anabolic Carbohydrates are the main source of
processes are those that build up the fuel for athletes, especially those
body, whereas catabolic processes are participating in endurance sports. It is
those that break down the body. Please more beneficial to eat a low glycemic
note that not all protein is equal in its carbohydrate (oatmeal, yams, brown rice,
ability to be anabolic vs. catabolic within 100% whole grains) meal 3–4 hours
the body. Protein is used as an energy before exercising or athletic competition.
source if calories are insufficient. A high glycemic carbohydrate meal
However, with sufficient calories, the (refined sugars in soda, candy, cake,
breakdown of amino acids (the building muffins, white bread, Gatorade) will result
blocks of protein) contributes only in a rapid release of insulin and
minimally to the total amount of energy ultimately reduced blood sugar,
used by working muscles. When a person suppressed release of fatty acids from fat
begins a moderate endurance exercise stores, and inhibition of liver glycogen
program, they initially lose more protein breakdown. Carbohydrate intake during
than they ingest; that corrects itself in intense exercise should average 25–30
order to promote increases in muscle size gm/30 minutes of activity. Carbohydrate
(hypertrophy) and increase in strength, it solution should not exceed 6–8%;
is an absolute requirement that athletes be otherwise, the athlete may experience
in a positive nitrogen status (ingesting cramps, nausea, and diarrhea. (To
determine the concentration in a sports TERMINOLOGIES
drink, the grams of carbs in a serving are
divided by the weight of the serving of the Physiology
drink, which is usually 240gm.) Post-
Physiology of Exercise
exercise, it is important for the individual to
restore muscle glycogen or carbohydrate Muscle Definition
stores by eating a source of carbohydrate
Adenosine Triphosphate
mixed with a small amount of protein.
(Refined carbohydrates work best at this Structure of Muscle
time—small baked potato, yogurt, or
Epimysium
Gatorade.) For the average exerciser this
is not a crucial step and is in fact where a Fascicles
lot of people are mistaken when they start
Perimysium
an exercise program. They tend to fuel
themselves more than they actually need Endomysium
and end up gaining weight. Periosteum Connective Tissue
Acetylcholine
Fluids Myosin Fibers
Water intake is a crucial part of our diet Myosin Filaments
that is often overlooked due to its lack Actin Filaments
of ―substance. However, if the
importance of a nutrient is judged by how Fuel Sources During Exercise
long we can do without it, water ranks as Glycogen
the most important. A person can
survive only eight to ten days without Blood sugar
water, whereas it takes weeks or even Blood fatty acids
months to die from a lack of food.
Water circulates through our blood and Intramuscular Triacylglycerols
lymphatic system, transporting oxygen Protein
and nutrients to cells and removing wastes
through urine and sweat. Water also Anabolic Processes
maintains the natural balance between Catabolic Processes
dissolved salts and water inside and
outside of cells. Our joints and soft Fat
tissues depend on the cushioning that Eicosapentaenoic acid
water provides for them. Too much water
Docosahexaenoic acid
dilutes the blood rapidly, increases its
volume and stimulates urine output. Blood Carbohydrates
dilution lowers both sodium and the
High Glycemic Carbohydrate Meal
volume-dependent part of the thirst drive
(making one less thirsty). Sufficient Fluids
amounts of electrolytes need to be
Lymphatic system
ingested with the water in endurance
athletes. After one hour of intense
exercise, sports drinks (or something
similar that contains electrolytes in a good
proportion) are highly recommended.
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