Muscular System
The muscular system is comprised of 3 different muscle types; cardiac muscle (the heart), smooth muscles, and skeletal muscles. Muscles and posture also go hand in hand, where regular exercise and movement tones muscles and improves your posture to reduce unnecessary strain on your body.
Skeletal Muscles are organs composed primarily of skeletal muscle tissue, but they also contain connective tissues, nerves and blood vessels.
Muscles and Functions
Triceps – Extend the arm at the elbow
Biceps – Flex the arm at the elbow
Deltoids – Move the arm in all directions at the shoulder
Pectorals – Adduct the arm at the shoulder
Trapezius – Hold the shoulders in place, move head back and sideways
Gluteals – Adduct and extend leg at the hips
Quadriceps – Extend the leg at the knee
Hamstrings – Flex the leg at the knee
Gastrocnemius – Pointing the toes, help to flex the knee
Latissimus dorsi – Adduct and extend the arm at the shoulder
Abdominals – Flex the trunk across the stomach
Muscles and Movement
Muscles contract when they work. Muscle contractions may be classified as isotonic or isometric based on the pattern of tension production and overall change in length. In an isotonic contraction, tension rises and the skeletal muscle’s length changes. In an isometric contraction, the muscle as a whole does not change length and the tension produces never exceeds the resistance
Types of Skeletal Muscle Fibers
Fast Fibers
Most of the skeletal muscle fibers in the body are called fast fibers because they can contract in 0.01 second or less following stimulation. Fast fibers are large in diameter and contain densely packed myofibrils, large glycogen reserves and relatively few mitochondria. The tension produced by a muscle fiber is directly proportional to the number of myofibrils so fast fiber muscles produce powerful contractions. However because these contractions use ATP very quickly, their activity is primarily supported by glycolysis, and fast fibers fatigue rapidly.
Slow Fibers
These fibers are only about half the diameter of the fast fibers, and they take three times as long to contract after stimulation; however they can continue contracting for extended periods, long after a fast muscle would have become fatigued. Three specializations related to the availability and use of oxygen make this possible:
- Oxygen Supply
- Oxygen Storage
- Oxygen Use
Muscle Performance
Muscle performance can be considered in terms of force, the maximum amount of tension produced by a particular muscle group, and endurance, the amount of time over which the individual can perform a particular activity.
Muscle tone can be seen when muscles are in a state of slight tension and they are ready for action. Regular training tones muscles and helps to create good posture. In addition, muscles will hypertrophy (increase in size) and develop better endurance
Muscle tone developed by regular exercise makes daily tasks such as shopping and gardening easier. It also helps to prevent injury as good posture reduces the strain on muscles, tendons and ligaments.
People with good posture also feel better about themselves. An upright body position is often a sign of self confidence. People who are less confident will sometimes show this in their body language, for example by adopting a slouched posture.
Anaerobic Endurance is the length of time muscle contractions can be supported by glycolysis and existing energy reserves of ATP and CP.
Aerobic Endurance is the length of time a muscle can continue to contract while being supported by mitochondrial activities. Aerobic endurance is determined by the availability of substrates for aerobic metabolism from the breakdown of carbohydrates, lipids or amino acids.
Muscle Tone is an indication of the background level of activity in the motor units in skeletal muscles. When inactive for days or weeks, muscles become flaccid and the muscle fibers break down their contractile proteins and grow smaller and weaker. If inactive for long periods, muscle fibers may be replaced by fibrous tissue.
What you don’t use, you lose!
How Will It Help?
Functions of the Skeletal Muscle:
- Produce movement of the skeleton
- Maintain posture and body position
- Support Soft Tissues
- Guard Entrances and Exits
- Maintain Body Temperature
