Loading ...
Sorry, an error occurred while loading the content.

Exercise in the prevention and treatment of insulin resistance

Expand Messages
  • gts
    Role of exercise training in the prevention and treatment of insulin resistance and non-insulin-dependent diabetes mellitus. Sports Med 1997 Nov;24(5):321-36
    Message 1 of 1 , Oct 2, 2002
    • 0 Attachment
      Role of exercise training in the prevention and treatment of insulin
      resistance and non-insulin-dependent diabetes mellitus.
      Sports Med 1997 Nov;24(5):321-36 (ISSN: 0112-1642)
      Ivy JL
      Department of Kinesiology and Health, University of Texas at Austin,
      USA. JohnIvy@....
      Recent epidemiological studies indicate that individuals who maintain
      a physically active lifestyle are much less likely to develop impaired
      glucose tolerance and non-insulin-dependent diabetes mellitus (NIDDM).
      Moreover, it was found that the protective effect of physical activity was
      strongest for individuals at highest risk of developing NIDDM. Reducing the
      risk of insulin resistance and NIDDM by regularly performed exercise is also
      supported by several aging studies. It has been found that older individuals
      who vigorously train on a regular basis exhibit a greater glucose tolerance
      and a lower insulin response to a glucose challenge than sedentary
      individuals of similar age and weight. While the evidence is substantial
      that aerobic exercise training can reduce the risk of impaired glucose
      tolerance and NIDDM, the evidence that exercise training is beneficial in
      the treatment of NIDDM is not particularly strong. Many of the early studies
      investigating the effects of exercise training on NIDDM could not
      demonstrate improvements in fasting plasma glucose and insulin levels, or
      glucose tolerance. The adequacy of the training programmes in many of these
      studies, however, is questionable. More recent studies using prolonged,
      vigorous exercise-training protocols have produced more favourable results.
      There are several important adaptations to exercise training that may be
      beneficial in the prevention and treatment of insulin resistance, impaired
      glucose tolerance and NIDDM. An increase in abdominal fat accumulation and
      loss of muscle mass are highly associated with the development of insulin
      resistance. Exercise training results in preferential loss of fat from the
      central regions of the body and should therefore contribute significantly in
      preventing or alleviating insulin resistance due to its development.
      Likewise, exercise training can prevent muscle atrophy and stimulate muscle
      development. Several months of weight training has been found to
      significantly lower the insulin response to a glucose challenge without
      affecting glucose tolerance, and to increase the rate of glucose clearance
      during a euglycaemic clamp. Muscle glucose uptake is equal to the product of
      the arteriovenous glucose difference and the rate of glucose delivery or
      muscle blood flow. While it has been known for many years that insulin will
      accelerate blood glucose extraction by insulin-sensitive peripheral tissues,
      recent evidence suggests that it can also acutely vasodilate skeletal muscle
      and increase muscle blood flow in a dose-dependent manner. A reduced ability
      of insulin to stimulate muscle blood flow is a characteristic of
      insulin-resistant obese individuals and individuals with NIDDM. Exercise
      training, however, has been found to help alleviate this problem, and
      substantially improve the control of insulin over blood glucose.
      Improvements in insulin resistance and glucose tolerance with exercise
      training are highly related to an increased skeletal muscle insulin action.
      This increased insulin action is associated with an increase in the
      insulin-regulatable glucose transporters, GLUT4, and enzymes responsible for
      the phosphorylation, storage and oxidation of glucose. Changes in muscle
      morphology may also be important following training. With exercise training
      there is an increase in the conversion of fast twitch glycolytic IIb fibres
      to fast twitch oxidative IIa fibres, as well as an increase in capillary
      density. IIa fibres have a greater capillary density and are more
      insulin-sensitive and -responsive than IIb fibres. Evidence has been
      provided that morphological changes in muscle, particularly the capillary
      density of the muscle, are associated with changes in fasting insulin levels
      and glucose tolerance. Furthermore, significant correlations between glucose
      clearance, muscle capillary density and fibre type have been found in humans
      during a euglycaemic clamp. Exercise training may also improve control over
      hepatic glucose production..
    Your message has been successfully submitted and would be delivered to recipients shortly.