Muscular System and Exercise the Essay

Disuse atrophy of the muscles is caused by prolonged inactivity, which often occurs after sustaining an injury. Hypertrophy of the muscles is achieved through regular diet and exercise. 1(p127) Two types of training, strength and endurance, greatly increase muscle condition. Strength training increases muscle condition through the use of resistance. While conditioning through resistance will increase the number of myofilaments in muscle fiber and increases muscle size, it will not increase the number of muscle fibers.1(p128) Resistance training has been shown to positively affect heart rate, stroke volume, and cardiac output, though not to the same extent as has been found through the extended practice and implementation of endurance training. 2 Long-term resistance training has also been found to reduce the resting heart rate, increase stroke volume at rest and exercise, maintain cardiac output at rest, decrease resting systolic and diastolic blood pressure while at rest, improve resting lipid levels, and show improved glucose sensitivity, insulin response and sensitivity.2(p4)

Endurance training increases the sustainability of moderate exercise over an extended period of time. Endurance training allows for the efficient delivery of oxygen and nutrients to a muscle through increased blood flow. Unlike strength training, endurance training will not result in increased muscle growth. 1(p128)

Precautions must be taken in order to prevent muscle damage through exercise. Damage to muscles is often encountered after eccentric movement or "unaccustomed exercise," especially if the exercise requires an inadequate amount of muscle lengthening contractions.3 Muscle damage incurred during the course of inadequate exercise may be evaluated through muscular biopsy or magnetic resonance imaging (MRI); inherent problems of muscular biopsies are the small amount of muscle tissue analyzed. MRI analysis allows for assessment of the entire muscle.3 (p2)

Damaged muscles must be given enough time to recuperate through time, physical therapy, and rest. While muscles are designed to stretch, upon reaching their threshold, muscles can become torn or strained. Muscle reconstruction commences at the cellular level at the time of injury. When a muscle is slightly damaged, one may experience muscle stiffness, whereas tearing through muscle tissue can result in swelling and bruising.4 on occasion, scar tissue will form instead of regenerated muscle tissue, which may lead to difficulty with normal contraction and elasticity of the skeletal 4

Studies have shown that improper preparation, fatigue, pre-existing and previous injuries are contributing factors to muscular injuries. 4 Additionally, studies have shown that a proper "warming-up period" will alter muscular properties, making it less susceptible to injury. 4

Conclusion

The skeletal system is a complex series of interconnected tissues that allows for the movement and functionality of the body through the support and maintenance of organs, structure, and exercise. With the proper training, the body can be strengthened subsequently reinforcing and increasing efficiency of surrounding body systems. With proper training, muscle mass may increase; an increase in muscular endurance has also been shown to occur. Injuries may be prevented through proper warm-up, and muscle conditioning.

1. Thibodeau GA. Structure & Function of the Body. 9th ed. Chicago, IL: Mosby Year Book; 1992.

2. Kell RT, Bell G, Quinney a. Musculoskeletal Fitness, Health Outcomes and Quality of Life. Sports Med. Edmonton, Alberta: ADIS International Limited; 2001.

3. Clarkson PM, Hubal MJ: Exercise-induced muscle damage in humans.

Am J. Phys Med Rehabil 2002;81(Suppl):S52 -- S69.

4. Freeman N. Muscle Injury and Healing. The Kai Echo. Available at http://www.ajjf.org/AJJF/kiaiEchoArticles/injuryAndHealing.php. Accessed February 9,.....