These are notes from a muscle physiology seminar given on September 9, 1999.

1. How Muscles Are Constructed
• There are 3 types of muscle:
• Skeletal = used to move the body or hold it upright
• Cardiac = only in the heart & can beat by themselves
• Smooth = used in all internal organ & blood vessels except the heart
• The rest of the information only for skeletal muscles
• All muscles are attached to the bones by tendons
• The muscle works in only one direction, pulling the bone toward the core of the body
• Although skeletal muscles can look different, they have the same basic structure
• A muscle are constructed of several large muscle bundles held together by a tough connective tissue called Fascia
• Muscle bundles are groups of muscle fibers again held together by its own fascia.
• Muscle fiber is constructed by a long series of motor units so it looks like it is striped.
• A muscle can contract unless it gets a nerve signal.
• Depending on what muscle, the nerve can signal a few to many fibers
• Muscle in the hands and face have few muscle fibers per nerve
• Muscles in the thigh have many muscle fiber per nerve
1. Muscle Motor Units- how the muscle moves
• The motor units consist of 2 types of smaller units called myofibrils.
• These myofibrils slide over each other to make the muscle contract
• When they slide apart when the muscle relaxes
• How much the muscle moves depends on how many of these motor units are contracted
• The more motor units contracting the faster you move or the more force you create
• There are 2 types of muscle fibers
• Fast twitch fibers = strong or fast movement but tire quickly ( pale in color)
• Slow twitch fibers = weaker or slower movement but good endurance ( dark in color)
• Some fast twitch fibers can be trained to have more endurance
• You inherit your muscle types
1. Muscle Size
• The basic ability to develop large muscle depends on the type of muscle fibers inherited
• Male also have testosterone, which signals muscles to increase muscle fibers.
• Most females can’t develop large bulking muscle only muscle tone.
• Exercise will increase muscle density or tone.
1. How Muscles Work
• Muscle movement is described by several terms
• Concentric = When the muscle shorten and moves the bone so the angle of the joint gets smaller. (Bending the elbow)
• Isometric = When the muscle tightens but the bone doesn’t move. ( tensing the muscle)
• Eccentric = When the muscle contract but the bone moves so the angle of the joint gets larger. ( straitening the arm)
• Muscles need oxygen and nutrition to work
• The muscle stores only 10 seconds worth of energy.
• The muscle then converts its sugar stores into energy but this creates a waste product called Lactic acid. This is what makes the muscles burn.
• If you get enough oxygen, the muscle converts the lactic acid back to sugar.
• The body can’t deliver oxygen fast enough, if the exercise is very intense or you are out of shape.
• Intense exercise can deplete the energy stores enough that they can move; this is called momentary muscle failure. Quickly as the blood delivers the oxygen and nutrient, the muscle recovers.
• Muscles need proper nutrition to work correctly.
• During intense exercise, it is important to get enough calcium and potassium
• Calcium- milk or calcium fortified orange juice
• Potassium- bananas or oranges
1. Training
• If you don’t continually train you will lose you fitness.
• Exercising develops cardiac endurance so your heart rate increases. This allows you to be more active without getting tired
• Most people need to improve both their muscle strength and muscle endurance so the recommended number of repetitions is
• 8 – 12 repetitions for the upper body
• 10 – 15 repetitions for the lower body
• 15 – 20 repetitions for the abdominal and low back
1. Flexibility
• Flexibility is a combination of muscle and ligament flexibility
• Although everyone can improve flexibility, much of it is inherited.
• Hyperflexion is when someone can move a joint at greater than the normal range. ( elbow that go beyond straight)
• These people must be careful not to hyperextend their joints.
• Much of flexibility is training the nerves to decrease muscle tension.
1. Injury and Safety Information
• Always tell someone if you are injured.
• If it is a minor injury, follow the acronym RICE
• Rest- give the injury time to recover
• Ice- put ice on the injury for 30 minutes on and then 30 minute no ice. Continue icing for 3 days before using heat. Heat increases the swelling and increases healing time.
• Compression- if possible wrap the injury with an ace bandage. This will not give support but will help reduce the swelling.
• Elevation- If possible elevate the injured body part to reduce the swelling
• Don’t exercise until the swelling is gone.
• It is okay to be slightly sore the next day after a workout. This means that there are small micro-tears in the muscle fiber. This will signal the body to strengthen the muscle fiber. Usually light activity will help with this soreness.
• It is not okay to be really sore, this means that there may be a large number of micro-tears or large tears in the muscle. Don’t exercise until the soreness is gone away.
• Remember to drink plenty of water- about ½ cup for every 15 minutes of activity.