Sarcopenia is the age related loss of muscle mass and strength which tends to predispose people to falls and fractures. The first signs may appear around 40 but accelerates after the age of 75. As muscle activity is decreased with age we also tend to loss calcium from our bones as the mechanical stress and tension on the bones declines. This was well exemplified in astronauts who initially loss copious amounts of calcium in their bones under conditions of weightlessness. It is also seen in hospitalized patients who are bed-ridden and unable walk for extended periods of time.
One of the major dietary factors in Sarcopenia is an inadequate protein intake. This is why we should always be mindful of our daily intake of protein as we age, especially easily digested eggs, fish or soft cheeses. Without adequate dietary protein (and thus the component amino acids, especially branched chain amino acids like leucine, isoleucine and valine), we find it difficult to manufacture new muscle proteins. One of the highest sources of branched chain amino acids is in whey protein. Many people are now choosing to take a whey powder milkshake on a daily basis to help prevent age-related muscle decline.
Too much protein on the other hand can cause metabolic acidosis and dietary protein should be consumed with plenty of fresh vegetables (which are alkaline and balance the acidity of the meat).
Others are compensating for the age-related decrease in hormone levels such as growth hormone, oestrogen, progesterone and testosterone by taking DHEA, testosterone and other hormone replacement therapy after seeing their local medical practitioner.
There is also good research to suggest that the amino acids cysteine and glutamine play an important role in maintaining muscle mass as we age. This is another reason why it makes sense to take a whey protein shake on a daily basis because it contains high levels of cysteine and also the major branched chain amino acid, leucine to kick-start muscle protein synthesis. (See Cribb,PJ. Sarcopenia and Whey Proteins. Implications, Mechanisms and Potential for Nutritional Intervention. US Dairy Export Council. Applications Monograph))