Safe Strengthening

Regardless of the fears that women have about developing excessive muscle, it is virtually impossible for females to build large muscles. Development of large muscles requires adequate amounts of testosterone, the male hormone. Women have only about one hundredth the amount the men do.

Sometimes women feel that they are building muscle for various reasons. For example, as the thigh muscles are firmed and toned, women sometimes feel that their pants are getting tighter. This is sometimes caused by increased muscle definition and not necessarily an increase in circumference. Also, as the skin tightens, the blood flow increases as does strength and firmness of the muscle beneath the skin surface. This new found tone will allow the woman to better feel the material close to her skin and she may think her pants are tighter.

The body-builder women you might have seen on TV are into extreme amounts of heavy weight lifting. Strength training for many hours a day can lead to body fat that is below what the female body needs. Women need about 8-10% of their body to be made up of fat, while men can function normally at 3-5%. When the body of a woman has less fat than is required for normal biological functions, the result is hormone imbalances and menstruation can stop. Only at that extreme level of exercise can women build huge muscles, it will NOT happen on accident or without your really, really, really trying.

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Muscle Action

Muscles never act singly to create an action, they act in groups. Even lifting an arm involves many muscles, and coordination as well. Muscles interact so that as one group contracts, the other group relaxes. For example, when the biceps contract, the triceps relax.

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  Muscle Endurance

Endurance can be increased by training designed to improve: the capacity of your muscles to store and burn muscle fuel, and the ability of your system to deliver oxygen to the muscles (aerobic= muscles must use oxygen to burn fuel). During exercise a muscle cannot take in enough energy-producing food products to replace what is being used up. This means that if you start out in an exercise program with a greater amount of glycogen stored in your muscles, you will have greater endurance.

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Factors That Limit Muscle Endurance

Loss of glycogen, the primary fuel of the muscles. Loss of fat reserves, a secondary source of fuel for the muscles.

Low levels of blood sugar, called hypoglycemia (blood sugar is a secondary source of muscle fuel).

Lack of oxygen, called hypoxia. Accumulation of lactic acid, a breakdown product of exercising without oxygen.

Heat buildup in the muscles, caller hyperthermia.  The opposite of hyperthermia is hypothermia is when the muscles get very cold, like when someone falls into a lake during winter.

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Energy Depletion in the Muscle

The amount of exercise you must perform to deplete your muscles varies widely, and depends on your level of training. The time and effort it takes to deplete muscle fuel is variable person to person, but also within the same person under different circumstances.

You can tell the muscles are depleting when they ache a little and you have trouble coordinating. Full depletion takes 10-15 minutes after the discomfort begins.

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Burning Fat

Frequent depletion will teach your muscles to burn a greater percentage of fat during all stages of exercise, to spare the muscle glycogen.

Burning fat with muscle glycogen is up to thirteen times more efficient that burning glycogen alone.

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Oxygen

Muscle glycogen and fat are converted into energy in the muscles by burning.

To burn these fuels efficiently, oxygen is needed.

Oxygen is delivered to the muscles through the bloodstream by the red blood cells.

The crucial factors in oxygen utilization are the ability of the muscles to extract the oxygen from the blood. Exercise improves this ability.

Especially: training the heart so it can pump a greater volume of blood with each stroke.

Training also enlarges your arteries so more blood can flow and increases the number if red blood cells so your blood-oxygen capacity is increased.

Finally, training also increases the rate at which enzymes in your muscles pick up oxygen from the blood.

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The VO2 Max

The maximum ability of your body to deliver oxygen to your muscles is limited by your genetic makeup and varies substantially between individuals.

The peak rate at which the body can take in and use oxygen is called the VO2 max (volume, oxygen, maximum).

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Lactic Acid

When glycogen is burned, it is broken down into a chemical called pyruvate.

If there is enough oxygen available, pyruvate converts to the end products: carbon dioxide, water, and heat.

If there is not enough oxygen in the muscles, pyruvate converts to lactic acid, which builds up in the muscles and then overflows into the bloodstream.

Lactic acid impedes muscle contractions and makes it increasingly difficult for muscles to move. As a result, you feel fatigue.

A high level of lactic acid will eventually stop the muscle from contracting altogether.

When this happens you lose control over the muscle, and it becomes painful and may cramp.

A shortage of oxygen, called oxygen debt, is signaled when you begin to breathe hard and pant during exertion.

This is the way your body tries to take in more air.

Every athlete incurs an oxygen debt and builds up some amount of lactic acid during competition, but trained muscles can continue to contract with a higher amount of lactic acid.

As soon as oxygen becomes available, lactic acid converts back to pyruvate and the to carbon dioxide and water.

Exercise with enough oxygen is called aerobic.

Exercise without enough oxygen is called anaerobic.

If you overexert and work so intensely that you run up an oxygen debt and build up lactic acid, you will tire quickly limiting the amount of work you can perform and the level of performance you can maintain.

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