Muscular Strength & Endurance

Muscular fitness can be divided into two subsets: muscular strength and muscular endurance. Muscular strength is the ability to apply maximal force. An example of muscular strength is lifting a very heavy weight one time. Muscular endurance is the ability to repeat an action over an extended amount of time. Being able to do multiple pushups or being able to shoot free throws over and over are examples of muscular endurance.

Before we discuss muscular strength and endurance, let's take a look at our skeletal system. Bones make up the the skeletal system and give our body it's original shape. Without the bones of our skeletal system we'd just be a blob of muscles in the sack of our skin. An adult has 206 bones in their skeletal system. The place where two or more of these bones meet is called a joint. There are three types of joints in the human body: 1) Freely Moveable, 2) Slightly Moveable and 3) Non-moveable

Ligaments hold the bones together at the joint and provide joint stability while limiting the range of motion at the joint. Ligaments are non elastic connective tissue. When a ligament has been stretched or damaged, the joint is less stable. Sometimes, therapy or surgery is required to repair damaged ligaments. An example of a ligament is the anterior cruciate ligament, ACL, which is one of the ligaments responsible for knee stabilization.

Having bone rub on bone is painful. Cartilage is a rubbery material which covers the surfaces of where two bones meet. It acts as a shock absorber, provides protection, and allows the joint to move freely. Osteoarthritis is a disease which can result in damaged, ineffective joint cartilage.

Flexibility is the ability to move joints through a full range of motion. Flexibility is joint specific. You can be more flexible in one joint than in another. Stretching exercises help improve your flexibility. Flexibility also improves as body temperature increases.

Skeletal or voluntary muscles allow for movement because they are attached to your skeleton. Movement at a joint is caused by contracting or shortening a muscle. Strong muscles also help provide support for joints. Muscles can be divided into three types: 1) Voluntary or Skeletal, 2) Involuntary and 3) Cardiac.

Voluntary or skeletal muscles are attached to the bones of the human body. These muscles are surrounded by connective tissue called fascia. At the end of the muscles, this connective tissues come together to form tendons which are thick, dense connective tissue which attach the muscle to the bone. Tendons are the continuation of the fascia which surrounds the muscle. An example of a tendon is the Achilles tendon which attaches your calf muscle to the heel bone of your foot. There is a tendon at each end of the muscle. The origin is the stationary attachment. It does not move when you contract the muscle. The origin of the biceps is at the top of the arm. The insertion is attached to the bone that moves when the muscle contracts. The insertion of the biceps is down past the elbow. This insertion point allows your arm to bend at the elbow when you contract the biceps.

Skeletal muscles are composed of muscle fibers which run the entire length of the muscle. You must send a signal to your skeletal muscles to make them contract. Your brain sends a signal down a nerve to the muscle fibers. This signal causes the muscle fibers to contract. These fibers are either fast twitch or slow twitch. Fast twitch fibers give you greater muscle power and tire easily. Power lifters are using fast twitch muscle. Slow twitch fibers contract slowly and work for a long time. Marathon runners are using slow twitch muscles. By working out, you can increase the size of the muscle fibers and increase your overall muscular fitness.

Muscular strength and muscular endurance can be improved through resistance training. You can use weight machines, free weights, resistance bands, medicine balls, weighted bars, stability balls, and the weight of your own body to improve muscular fitness. Through resistance training, the size of the muscle fiber increases as an increased load is used. Untrained people will notice a greater gain when doing resistance training.

Resistance training can be divided into 3 types: isotonic, isometric and isokinetic. Isotonic exercises require you to contract a muscle against a moveable load. The speed at which you move does not have to stay constant throughout the entire range of motion. Using weight machines is an example of an isotonic exercise. Isometric exercises are also called static workouts because you contract the muscle but don't move the joint. Wall situps and a plank are examples of isometric exercises. Isokinetic exercises require expensive specialized equipment that allow you work out at a full range of movement (like isotonic) but at a constant speed.

Resistance Training

Designing a Workout


Stretching is the process of elongating muscles and connective tissue. Make sure and involve all major muscle groups with one stretch per each group allowing for full range of motion during each stretch. Hold each stretch for 15 - 20 seconds and then take the stretch deeper. Remember to check how you feel about two hours after finishing. You should not feel worse. If you do, you have stretched too deeply.



muscle fiber
Structure of a Skeletal Muscle
Image from SEER Training website

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