Protein is required for normal muscle development, function, and recovery after exercise and injury. Resistance exercise, such as weight training, helps build muscle, too, but only if there's enough dietary protein around to replenish muscle protein losses after a workout.
While we know that protein can help boost muscle gain after a single workout, less is known about protein's long-term effects on muscle mass and strength in people who work out regularly.
Pack a punch with protein
Researchers from the Netherlands combined the results of 22 trials to examine the effects of protein supplementation on muscle mass and strength in 680 people who took part in prolonged resistance-training programs (two or more exercise sessions per week for six or more weeks). The results were separated by age: "younger" people were about 23-years-old, and "older" people were 62-years-old, on average.
On top of their normal diet, the people supplemented with about 50 grams of additional protein per day during the trials. The studies assessed the people's fat-free mass (includes muscle, bone, and water), muscle fiber size, and muscle strength.
Compared with placebo, protein supplementation significantly increased fat-free mass in younger people.
Muscle fiber size also increased by up to 54% and muscle strength improved by 20% in younger participants.
Fat-free mass increased by 38% and muscle strength improved by 33% in the protein-supplemented older group compared with the placebo group.
"The greater increase in muscle mass and strength will allow older individuals to more rapidly regain their functional capacity, thereby reducing the risk of falls and fractures and, as such, supporting a more active independent lifestyle," commented the researchers.
Are you getting enough protein?
Many people, especially seniors, come up short of their daily protein requirements. Most adults need at least 0.8 grams of protein per day for every kilogram of body weight. For a 150-pound person, that's about 54 grams of protein per day. Protein requirements increase with exercise, so ask your doctor about how much is right for you. Here's an easy reference for everyday living:
1 cup of milk contains 8 grams of protein.
Meat and fish contain about 7 grams of protein per ounce.
1 egg contains 6 grams of protein.
1 ounce of almonds contains 5 grams of protein.
½ cup of beans contain 7 to 10 grams of protein.
(Am J Clin Nutr 2012;96:1454-64)