Chronic inflammation and the effect of IGF-I on muscle strength and power in older persons

Am J Physiol Endocrinol Metab. 2003 Mar;284(3):E481-7. doi: 10.1152/ajpendo.00319.2002. Epub 2002 Nov 5.


Deregulation of the inflammatory response plays a major role in the age-related decline of physical performance. The causal pathway leading from inflammation to disability has not been fully clarified, but several researches suggest that interleukin-6 (IL-6) causes a reduction of physical performance in elderly through its effect on muscle function. In vitro studies demonstrated that IL-6 inhibits the secretion of insulin-like growth factor I (IGF-I) and its biological activity, suggesting that the negative effect of IL-6 on muscle function might be mediated through IGF-I. We evaluated the joint effect of IGF-I and IL-6 on muscle function in a population-based sample of 526 persons with a wide age range (20-102 yr). After adjusting for potential confounders, such as age, sex, body mass index, IL-6 receptor, and IL-6 promoter polymorphism, IL-6, IGF-I, and their interaction were significant predictors of handgrip and muscle power. In analyses stratified by IL-6 tertiles, IGF-I was an independent predictor of muscle function only in subjects in the lowest IL-6 tertile, suggesting that the effect of IGF-I on muscle function depends on IL-6 levels. This mechanism may explain why IL-6 is a strong risk factor for disability.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Aging / physiology*
  • Chronic Disease
  • Female
  • Hand Strength / physiology*
  • Humans
  • Inflammation / physiopathology*
  • Insulin-Like Growth Factor I / metabolism*
  • Interleukin-6 / metabolism
  • Male
  • Middle Aged
  • Muscle, Skeletal / physiopathology*
  • Prospective Studies


  • Interleukin-6
  • Insulin-Like Growth Factor I