Maintaining Strength and Muscle Mass As We Age

An article entitled, “Staying Strong: How exercise and diet can help preserve your muscles” appeared in the April 2011 issue of the Nutrition Action Health Letter, a publication of the Center for Science in the Public Interest. The article stated some interesting facts, including:

• Starting in their late 30s and early 40s, most people lose a quarter pound of muscle per year.
• Several studies have shown that resistance exercise can restore and preserve strength and power, even at an advanced age.
• Resistance exercise also helps prevent loss in bone density and may even reverse age-related loss.
• People with Type II diabetes can lower their blood sugar by doing resistance exercise.
• After a large protein feeding (~ 30 grams, the quantity in 4 ounces of cooked meat) both younger and older people show equivalent protein synthesis (muscle-building) responses.
• After a small protein feeding (~ 14 grams, the quantity in an egg plus a glass of  milk) younger people synthesize about half the protein they synthesized in the large feeding BUT PEOPLE OVER 60 SHOW ALMOST NO PROTEIN SYSTHESIS. In other words, the larger protein portions are necessary for the older people to synthesize any protein at all. However, anything above 30 grams of protein in a meal is either burned off as energy or stored as fat. So extremely large protein meals do not aid in muscle-building.
• Of the 9 essential amino acids that our bodies can’t manufacture and must ingest, leucine is by far the most important for muscle development, especially for older individuals. Researchers recommend a minimum of 3 grams of leucine per meal, in addition to other amino acids. Animal products generally have relatively high percentages of leucine. Protein from whey (a byproduct of cheese-making) is relatively high in leucine and makes a good protein supplement.
• Plant protein contains a smaller percentage of leucine, but soy is the best of the common plant proteins in regard to leucine content.
• According to researchers, ingesting protein shortly after exercise provides the greatest boost for muscle building. Two hours is the longest one should wait before ingesting protein after resistance exercise.
• While the U.S. Institute of Medicine set a Recommended Daily Allowance (RDA) of 0.36 grams of protein per pound bodyweight per day, researchers feel that about 0.50 grams of protein per pound bodyweight per day can best promote muscle building and minimize muscle loss as we age.

Bottom Line
Regular resistance exercise and adequate protein intake are essential for increasing and maintaining strength and muscle mass, especially as we age. A daily protein intake of half a gram per pound bodyweight is recommended (e.g. a 200 lb person should take in 100 grams of protein daily). The protein should not be concentrated in one meal but should be distributed over the day in meals containing about 30 grams of protein.