Skeletal muscle function in older people

Original Editors - Saeed Dokhnan

Top Contributors - Saeed Dokhnan  


 






Introduction

Aging effects all body organs and systems , one of these systems which we consider to discuss in this page is the skeletal muscle, there are many changes that occur to the muscular system due to aging process,.

By the age of 80, 40-50% of muscle sstrength, muscle mass, alpha motor neurons and muscle cell are lost. [1]

In  this page we will highlight the most important changes to muscles which affect their performances, and as the muscle and motor unit are interrelated to each other it is important to include the motor unit in this process

Effect of aging on the Motor Unit

In the aged motor unit there are decreased in the number of functional motor units associated with enlargement of the Cross sectional area of the remaining units, this motor unit remodelling is achieved by selective denervation of muscle fibers, especially type 2 b fibres, followed by re-ennervation by axonal spouting from juxtaposed innervation units

Effect of aging on the muscle

Muscle strength:

Muscle strength Muscle strength is reduced with age advances, generally weakness starts in the 3rd decade of life and progress with individual goes older, estimated 8% / decade the muscle strength will decrease[2]

FACTORS AFFECTING MUSCLE STRENGTH

1. Exercise,  will iprove muscle strength

2. Diet,   proper diet will postponed the aging process

3. Trauma will increase muscle fiber degeneration

FEATURES of aged muscle:

1. Weakness

2. Decrease muscle mass

3. Decrease capillaries and blood supply to the muscle fibers

3. Incease fat deposition which substitutes muscle fibers

SPEED OF CONTRACION:

Velocity of muscle fibers to contract in response to motor nerve firing is decreased which leads to overall decrease in muscle contraction time

MUSCLE ENDURANCE

as the aging muscle advances the ability of muscle capillary system to carry out muscle nutrition is deceased,  thereby the endurance drop and muscle fatigue easily occur.

MUSCLE MASS

aging process wigh physically inactive people will have muscle mass destruction and theire muscles become hypotrophy, these can be delayed by been physically active.

PROTEIN METABOLISM

protein synthesis decreases with age advance and the balance between synthesis and breakdown is disturbed

Recent related research(from pubmed)

http://www.ncbi.nlm.nih.gov/pubmed/24948676

http://www.ncbi.nlm.nih.gov/pubmed/24903024

References

  1. Timothy L.et.al 2007
  2. Schiller et al 2000
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