The human body has skeletal or striated-voluntary muscle, cardiac or striated-involuntary muscle and smooth or unstriated-involuntary muscle. At rest or less than maximal exercise intensities, your muscles get their energy from aerobic respiration or the production of energy with the use of oxygen. These muscle cells need the energy to help you move, to maintain your heartbeat, to digest your food and even to change the size of your pupils.
Heart Muscle
Your heart is made up mostly of cardiac muscle. The function of your heart muscle tissue is to contract and relax, circulating oxygenated blood between your lungs, heart and body. Your heart has its own electrical system that receives automatic stimulation from your nervous system. Diseased, thickened heart muscle resulting from abdominal obesity is unable to properly pump blood throughout your body. Aerobic exercise improves the function of your heart.
Eye Muscles
Your eyes have voluntary and involuntary muscles. The extrinsic muscles of your eye are voluntary, skeletal muscles located around your eyeballs. The intrinsic muscles of your eye are involuntary, smooth muscles and located within your eyes. You have four voluntary rectus muscles and two voluntary oblique muscles around each eyeball that enable you to move your eyes. The ciliary muscle is an involuntary muscle just behind your pupil and controls the shape of your lens. The iris is also involuntary and controls the size of your pupil. Your eyes must be level with the horizon in front of you in order to keep your balance.
Digestive Muscle
The muscularis is your gastric muscle. It begins as two layers in your esophagus and ends as one layer in your large intestine. The thickest part of your muscularis is in your stomach wall. There, the muscularis has muscle fibers which run in longitudinal, diagonal and circular directions. This arrangement enables your stomach to strongly contract and mix your food. The main function of your muscularis muscle is to move and break down food from your esophagus through your large intestine, absorbing nutrients and preparing waste to be excreted. You need to eat at least one to two hours before you exercise so that blood is optimally delivered to your digestive muscle to break down your food instead of to your skeletal muscles.
Skeletal Muscles
You have more than 600 skeletal muscles in your body. Each muscle cell has proteins connected to each other in a particular arrangement such that when they are stimulated, you can move your body parts. The primary function of skeletal muscles is to move. Your muscles also produce the major portion of your body heat. This maintains an optimal internal environment for all the cells of your body to function. Some of your muscles are always contracting in order to maintain your posture. When you are standing, sitting and walking around, your muscles are working to keep you in an upright, stable position. During exercise, your spinal, lower back and abdominal muscles work harder to maintain your balance and stabilize your body.
References
- “Anatomy & Physiology”; Gary Thibodeau, Ph.D. and Kevin Patton, Ph.D.; 2007
- “Exercise Physiology, Energy, Nutrition & Human Performance”; William McArdle, Frank Katch and Victor Katch; 2007
- “Equal But Not The Same, Considerations for Training Females”; C.H.E.K. Institute; 1997
