"Muscle loss is quite common with aging and accelerated with unexpected bouts of inactivity, illness or even a brief hospital stay in aging adults," explained Stuart Phillips, senior author and director of the Physical Activity Centre of Excellence (PACE) at McMaster University. "The aim of our study was to determine if one type of protein supplement (30 g of whey or collagen consumed twice daily) could optimize how well muscle made new proteins by measuring muscle protein synthesis during recovery from a period of inactivity—to recover lost muscle."
Older adults often experience sarcopenia, a condition characterized by the loss of muscle and strength. Because it can adversely affect overall health, balance, gait and the ability to perform the simple tasks of everyday life, the team from McMaster set out to determine if protein type could aide in recovery following a period of inactivity.
"We chose to compare whey protein versus collagen protein because they differ in the amount of leucine they provide," said Sara Oikawa the lead author and a graduate student in the Department of Kinesiology at McMaster. "The essential amino acid, leucine, has been shown to be a key stimulator of muscle protein synthesis. Whey protein from dairy has a greater amount of leucine than almost all other commonly available proteins."
Researchers recruited men and women who were non-smokers, non-diabetic and between the ages of 65 and 80 years old. The participants were divided into two groups—each group consumed a diet containing 55% of protein from foods and 45% of protein from supplements of either whey protein or collagen protein during the five-week period. Additionally, both groups experienced a two-week simulated hospital stay or bout of inactivity. Their daily steps were restricted to 750 per day and their calorie intake reduced by 500 calories. A one-week recovery period immediately followed where participants returned to normal activity levels.
During the periods of reduced activity and calorie intake, both the groups experienced decreased muscle mass. To the surprise of the researchers, neither protein supplementation protected muscle mass during inactivity and calorie-restriction.
"Previous research has shown that complete proteins (providing all of the essential amino acids in levels at or greater than needed) stimulate the muscle building processes," said Ms. Oikawa, "which is why we were surprised to discover that there were no apparent differences in muscle loss between the two groups. Clearly inactivity is hard to overcome!"
The key result here is that, when activity returned to normal during the one-week recovery period, muscle protein synthesis and muscle rebuilding was significantly greater in the group consuming whey protein. The collagen group did not see any improvements. While protein was ineffective in mitigating muscle loss, the authors state that when participants returned to normal physical activity, the whey group recovered significantly more skeletal muscle mass in comparison to the collagen protein group.
"The remarkable takeaway is that proteins—even if ‘complete’—are not created equal. Formulations designed to enhance seniors' muscle health should include the right protein in the ingredients," advised Dr. Phillips, "Our data shows that for seniors, collagen isn't a great choice, whereas whey protein is very effective. Whey is a high-quality protein that can be superior for muscle stimulation and recovery in older adults."
Funding for this study was provided by the Whey Protein Research Consortium and National Dairy Council.