How much milk protein can stimulate muscle growth after exercise in middle-aged men?
The study, published in the Journal of the International Society of Sports Nutrition, looked at the minimum dose required to enhance anabolic (or muscle building) signaling response to a single bout of resistance exercise.
Minimum dosage is a metric the researchers argued was important to establish because “the addition of large amounts of protein to mass market products can increase the cost to the consumer, alter taste, and limit formulation options”.
Furthermore, production of whey protein is produced is limited relative to milk protein concentrates, yet it remains the popular muscle-building ingredient. Researchers of this present study were building off a previous trial, also conducted with Fonterra, which found milk protein concentrate consumption resulted in equivalent anabolic response to a matched dose of whey protein among middle-aged men, thus potentially providing an economic alternative ingredient for the sports nutrition industry.
Participants and study beverage
The randomized, double blind, placebo-controlled study required participants to go through four sets of leg exercises, and then consume an assigned beverage within three minutes.
Twenty men aged 38 to 55 participated. Criteria for inclusion was that participants were not on any medication, and had no neuromuscular, metabolic, or cardiovascular medical conditions. The men were sedentary to recreationally active, but do not normally participate in resistance training.
Studying middle-aged men was unique, the researchers argued, because “most studies that measure muscle anabolism after exercise and feeding investigate either young adults or older adults—for this reason much less is known about the dose response of anabolic signalling to exercise and protein feeding in middle age.”
They were divided into two groups and each were assigned one of two beverages: A functional milk drink with 9g of milk protein concentrate by Fonterra, or an isoenergetic carbohydrate placebo. Powders were dissolved in 250ml of water. The dose was just one gram less than what researchers used in a previous study, where they found that 10 g was sufficient to stimulate muscle protein synthesis.
Findings: Nine grams of milk protein may enhance muscle anabolism
Researchers analyzed the participant’s blood sample before and after exercise, as well as a muscle biopsy obtained from the leg 90 and 240 minutes after liquid supplements were consumed.
They found that just nine grams of milk protein was sufficient to augment some measures of downstream mTORC1 signaling after resistance exercise, commonly agreed in the sports nutrition space as an indicator of muscle protein synthesis.
This dose did not increase amino acid transporter expression, which means that “nine grams of milk protein is likely to enhance muscle anabolism even though the magnitude of this potential effect is difficult to quantify based on the current data.”
But the researchers argued that these findings still have relevance for the circa $12bn sport nutrition industry, a full 82% of that value coming from protein products, as per Euromonitor data. “Formulated products containing 9 grams of milk protein would be expected to exert a stimulatory effect on muscle anabolism after resistance exercise,” they wrote.
“This may be of benefit in the development of food products targeted towards population groups that are unable to tolerate single dose high-protein products or that are unfamiliar with the tastes and sensory properties of high-protein supplemental foods and beverages.”
Source: Journal of the International Society of Sports Nutrition
Published online, doi: 10.1186/s12970-017-0175-x
Minimal dose of milk protein concentrate to enhance the anabolic signalling response to a single bout of resistance exercise; a randomised controlled trial
Authors: Cameron J. Mitchell, et al
