What are the causes of sarcopenia
Sarcopenia is a complex multifactorial syndrome. Multiple factors, interdependent, participate in the development and progression of sarcopenia.
These factors contribute, with varying degrees, to the loss of muscle mass :
• An increase in splanchnic extraction (that is to say, the retention of dietary amino acids by the gut and liver for their own needs) of amino acids is observed and this limits the postprandial bioavailability of amino acids in older persons and therefore the anabolic response1,2;
• Nutritional intake not adapted to the needs of the body during aging3;
• The effect of anabolic hormones is disrupted during aging. Either the concentration of circulating hormones is reduced4,5, or the sensitivity of the muscle to the action of certain hormones such as insulin appears to be less6;
• Denervation and loss of functional motor units is observed during aging and this would result in a lesser constructability of muscle fibers7.
References :
1. Boirie Y, Gachon P, Beaufrère B. « Splanchnic and whole-body leucine kinetics in young and elderly men » Am. J. Clin. Nutr. 1997 févr;65(2):489-95.
2. Jourdan M, Cynober L, Moinard C, Blanc MC, Neveux N, De Bandt JP et al. « Splanchnic sequestration of amino acids in aged rats: in vivo and ex vivo experiments using a model of isolated perfused liver » Am. J. Physiol. Regul. Integr. Comp. Physiol. 2008 mars;294(3):R748-755.
3. Boirie Y. « Physiopathological mechanism of sarcopenia » J Nutr Health Aging. 2009 oct;13(8):717-23.
4. Tenover JL. « Testosterone and the aging male » J. Androl. 1997 avr;18(2):103-6.
5. Perrini S, Laviola L, Carreira MC, Cignarelli A, Natalicchio A, Giorgino F. « The GH/IGF1 axis and signaling pathways in the muscle and bone: mechanisms underlying age-related skeletal muscle wasting and osteoporosis » J. Endocrinol. 2010 juin;205(3):201-10.
6. Guillet C, Boirie Y. « Insulin resistance: a contributing factor to age-related muscle mass loss? »Diabetes Metab. 2005 déc;31 Spec No 2:5S20-25S26.
7. Vandervoort AA. « Aging of the human neuromuscular system ». Muscle Nerve 2002 janv;25(1):17-25.
What are the consequences
Sarcopenia is causing a general deterioration of the physical condition resulting in a loss of muscle mass and strength leading to an increased risk of falls, loss of independence and inevitably leads to dependance.
