Chugging a protein shake after a heavy-duty workout has long been the practice of bodybuilders and athletes. But for children and teens who do sports, it’s especially important to take in protein after exercise, says a Brock University exercise physiologist.

“It’s very dangerous for children and adolescents’ developing skeletons and anti-inflammatory processes if they don’t replenish quickly with enough nutrients for their body after exercise,” says Professor of Kinesiology Nota Klentrou.

To investigate this further, Klentrou has led a series of studies on how protein supplementation affects various physiological processes in active children and youth.

It turns out whey powder and Greek yogurt are ideal protein sources to help young bodies fight inflammation and ultimately get stronger.

In one study, published in October 2020, lead author and then-PhD candidate Brandon McKinlay (MSc ’16, PhD ’21), Klentrou, Professor of Kinesiology Bareket Falk and their team examined the effect of post-exercise whey protein consumption on subsequent exercise performance, muscle damage and inflammation in a group of 58 male and female adolescent competitive swimmers.

Research participants performed several swims spread out over a couple of days. Following each swim, they were given either whey protein, a carbohydrate solution or water; neither they nor the researchers knew what they consumed at the time.

Researchers collected participants’ blood samples at three points over 24 hours.

A similar process occurred in a subsequent study in March 2022 that McKinlay was also the lead author on. The research team examined how plain Greek yogurt affected the performance and muscle recovery of adolescent female soccer players during an intensified soccer training camp.

During two five-day soccer-specific training camps, 13 adolescent girls ate three servings a day of either plain Greek yogurt or a carbohydrate pudding. Neither the participants nor the researchers knew which ones they took at the time.

Performance and fatigue levels were assessed before and after each training camp, with blood samples drawn at several points.

In both studies, the research team found that while post-exercise consumption of whey protein appeared to have no additional benefit for subsequent performance, it helped the adolescents’ muscles recover from inflammation. Swimmers and soccer players who took the whey protein reported having fewer sore muscles.

Klentrou explains that during the exercise process, muscles are torn, suffer damage and become painful and inflamed. The inflammation process directs blood flow to areas needing repair.

In the short-term, inflammation is good because it helps tissue repair and regeneration, she says. But “we don’t want that inflammation to drag on for a long time in athletes who need to perform and are younger in age. They need extra protein not only to repair their muscles, but for their growth and development.”

Another concept the researchers looked at is a process called ‘bone turnover,’ which occurs when bone tissue breaks down and is replaced by new bone. Through this process, bone regenerates, continuously preserving and increasing its density and strength.

Then-master’s student Alexandros Theocharidis (MSc ’19) worked with the same group of 58 male and female adolescent competitive swimmers who were in the whey protein study to see how whey protein supplementation affects bone turnover in adolescent swimmers.

In their April 2020 study, Theocharidis and the team found the adolescents consuming the protein supplement had a “significantly higher calculated rate of bone turnover” eight and 24 hours after their intense swims.

“This increase in bone turnover is important in younger populations as higher rates of bone turnover are associated with greater bone growth,” says the study.

Klentrou says these and other studies performed by her research group highlight the need for young athletes to get the protein and calcium they need to prevent stress fractures and ensure proper development.

“Any lifestyle strategy that can promote bone accretion during adolescence is beneficial because it can lead to a higher peak bone mass and improvement in bone mineral density in the long term,” says Klentrou. Peak bone mass is the amount of bony tissue found once the skeleton fully matures, typically between the ages of 25 and 30.

“High-performance sports have to come with good nutritional strategies,” she says.