ABSTRACT
The main function of skeletal muscle is to provide power and strength for locomotion and posture, but the tissue is also the major reservoir of body proteins and amino acids. The resulting weakness increases the incidence of falls and the length of recovery and when advanced, muscle wasting is correlated to morbidity and increased mortality. However, as observed for free leucine supplementation, when such dietary proteins where given on the long term in elderly rodents, muscle anabolism was acutely improved but muscle mass remained unchanged. A possible nutritional strategy is then to increase the intake of anabolic factors to reach the new “anabolic threshold”. Because the muscle “anabolic threshold” is more elevated, the duration of the stimulation by anabolic signals and the overcome of amino acid supply the threshold is reduced with usual nutrient intake. Sarcopenia, catabolic states, has been found to result from a decreased response and/or sensitivity of protein synthesis and degradation to physiologic concentrations of amino acids.
