- A new study finds evidence that protein shakes may not help your muscles recover much after a grueling workout.
- Participants reported muscle soreness and reductions in muscle power and function after working out and having a protein shake.
- The study was small, and experts say more research is needed.
If you reach for a protein shake after a session of heavy weights at the gym, you may not be doing the good you think you are.
Indeed, weightlifters and even everyday gym goers have been told that the key to successful muscle repair after any weight-intensive session is to drink protein shakes.
But a new study from the United Kingdom’s University of Lincoln suggests that protein shakes are no more effective at rebuilding muscle and boosting recovery than high-carbohydrate drinks, like sports drinks.
Indeed, the British researchers say that neither whey protein-based shakes nor milk-based shakes enhanced muscle recovery or eased soreness compared to a carbohydrate-only drink.
That refutes a great deal of exercise knowledge, so it’s important to look at the specifics of the study.
For the study, which was published in the Journal of Human Kinetics, researchers recruited 30 males between the ages of 20 and 30. All participants had at least a year’s experience with resistance training prior to the study.
The 30 participants were divided into three groups. Each group was assigned to consume either a whey hydrolysate drink, a milk drink, or a flavored carbohydrate drink after a prescribed intensive resistance training session.
After the workout, the participants were re-tested and asked to rate their levels of muscle soreness on a scale from zero (“no muscle soreness”) to 200 (“muscle soreness as bad as it could be”). The researchers also asked the participants to complete a series of strength and power assessments, including throwing a medicine ball while seated and jumping as high as possible from a squatted position.
At the start of the study, all participants rated their muscle soreness between 19 and 26, or quite low. Then, they reassessed those measurements 24 and 48 hours after the weight-lifting session. All participants rated their soreness above 90, which is quite high.
What’s more, in the physical assessments, the participants showed reductions in muscle power and function.
However, there was no difference in recovery response and soreness scores between the three different groups. That means, the study’s authors concluded, that there is no additional benefit in consuming protein shakes or drinks for the sake of muscle recovery.
“While proteins and carbohydrates are essential for the effective repair of muscle fibers following intensive strength training, our research suggests that varying the form of protein immediately following training does not strongly influence the recovery response or reduce muscle pain,” lead author Thomas Gee, PhD, program leader of strength and conditioning in sport at the University of Lincoln, said in a statement. “We would hypothesize that well balanced daily nutrition practices would influence recovery from delayed onset muscle soreness to a greater extent.”
These results seem surprising, precisely because they refute decades’ worth of common workout wisdom. Previous research has shown that protein can ease soreness, speed up recovery, and help repair the muscles that are torn during weightlifting. Plus, one review of nearly 50 studies found that protein supplementation greatly enhanced muscle strength and size during resistance training.
Therefore, it’s important to point out a few issues with this study that you should consider when weighing whether to shake up a drink after leg day.
First, the study is quite small — it had just 30 participants. Many small-scale studies are reported on — and many of the studies in this field of research are likewise small —s o the caveat with these should always be that larger, more expansive studies are needed to verify the results.
Second, despite using three different beverages, the researchers used no control. In other words, they didn’t have a group that consumed just water. With this, they might have been able to determine if nutrient-rich drinks have any value at all in recovery.
“Recovery and repair of muscles does not just come down to only protein,” says Melissa Morris, EdD, a professor of applied kinesiology at the University of Tampa. “You must also consider the type of workout, rest, hydration, and overall nutrition, which makes it complicated to link just protein to repair and recovery.”
Indeed, muscle repair and rebuilding requires both protein and carbohydrates. Protein helps restore the muscle and build strength; carbohydrates refurbish the glycogen levels. Glycogen is a substance that’s stored in the muscles and used by the body for energy.
In short-term recovery — say, 24 to 48 hours after a workout — it’s possible the mix of nutrients doesn’t matter as much. But in the long term, having high-quality protein with carbohydrates may win out over carbohydrates or protein alone. Additional research would be needed to verify that.
“In my 15 years of coaching experience, what seems to matter most for recreational athletes, or regular people, is the total amount and quality of protein eaten over the day, rather than the specific time of the protein intake,” says sports nutritionist Jonathan Wong, CEO and founder of Genesis Gym.
Perhaps this study points out that protein and carbohydrates in isolation aren’t the solution. The next study in this area may benefit from comparing drinks with a combination of protein and carbohydrates to ones with one macronutrient alone.
“The goal isn’t to just think about protein,” says Rachel Fine, MS, RD, owner of To The Pointe Nutrition. “To best optimize post-workout muscle repair, a mix of carbohydrates and protein is key.”