More than 90% of your skeletal muscles, including the contractile filaments that slide past one another when a muscle fiber contracts, are made of protein. When you lift weights, you damage these proteins and they must be repaired. Otherwise, you won’t gain strength or muscle size. To make these repairs and build new contractile filaments, your muscles need protein, more specifically they need amino acids. No doubt about it, protein is an important macronutrient, especially for guys and gals who want to get more defined.
You Need More Protein if You Work Out
You’ve probably heard that you need more protein than a sedentary person if you lift weights. Sources suggest that you may need as much as twice the recommended amount, 0.8 grams of protein per kilogram of body weight if you work out intensely. You might assume, based on the formula, that you need more protein after a strength workout if you weigh more or have more lean muscle. Yet a new study calls this idea into question.
What a New Study Shows
This study, carried out by the University of Stirling in Scotland, challenges the idea that you need more protein after a workout if you’re bigger or have more muscle mass. In this study, researchers divided 86 young adult males into two groups. One group had more lean body mass than the other. Both groups were experienced in resistance training.
In two separate trials, the men did a full-body resistance training routine, lifting at 75% of their one rep max. Each did three sets of 10 repetitions before completing another set to failure. During the second trial, they did a similar workout. In the first trial, the men consumed 20 grams of whey protein after working out. In the second, they consumed double that amount, 40 grams of whey protein. To see what impact the protein had on muscle protein synthesis, researchers measured metabolic markers and took muscle biopsies from the men.
What they found was that the muscle protein response to the two protein doses didn’t differ between the participants, despite their weight difference. So, why are previous protein recommendations based on body weight? The studies used to come up with these guidelines looked at the response to lower body training, specifically leg training, rather than total body weight training as in this study.
The Amount of Protein You Need After a Workout Depends on Your Workout
The researchers believe, based on the results, that the amount of protein you consume after a workout might best depend on how many muscle groups you work in a session, not your body weight. In other words, you need more protein after a total body workout than a workout that focuses only on your upper body. It’s not so important how large you are or how much muscle you have on your body but the type of workout you’re doing.
In many ways, this study makes sense. If you work multiple muscle groups with a whole body workout, you’ll sustain more damage to muscle fibers than if you work a single or only a few muscle groups. That damage needs to be repaired and your muscles need amino acids from protein to act as building blocks. More damage means higher protein needs post-workout.
Another observation the researchers made was that the higher dose of protein (40 grams versus 20 grams) promoted greater muscle protein synthesis and repair than the lower dose. This was independent of the size of the individuals and how much muscle mass they had.
So, all in all, consuming a higher dose of protein after a workout may give you an edge in terms of muscle recovery, and growth but the quantity you need is no different than someone who has more lean body mass. It’s independent of how big you are. Remember, this study only involved young, resistance-trained men. Does it apply to both genders and all age groups? That remains to be seen.
Is There an Anabolic Window?
You may have heard there’s an “anabolic window” after a workout where your body benefits the most from protein. According to sources, this is the time your body is primed to convert the amino acids from protein-rich food into muscle tissue. Other studies don’t support the idea that consuming protein right after a workout boosts muscle protein synthesis more than getting the same amount at other times. How long is the theoretical anabolic window? About an hour after completing a workout.
Your body not only needs protein but carbohydrates after a training session. What’s questionable is whether you need to rush to drink a protein drink or eat a protein-rich meal after a workout due to the anabolic window. At the other end of the spectrum, you shouldn’t wait for hours to eat a carbohydrate/protein meal. If your glycogen stores are depleted and you don’t replace them, your body can enter a catabolic state where you get muscle breakdown. Carbohydrates have a “protein sparing” effect and help you hold on to your hard-earned muscle tissue.
Consuming carbohydrates with protein after a workout also raises your insulin level. While you don’t want an insulin spike when you’re just sitting around, it comes in handy if you’ve just done a workout. Insulin helps gets amino acids into muscle cells where they can be used to repair and build new muscle tissue. That’s why after a workout is the best time to take in rapidly absorbed carbohydrates.
The Bottom Line
This most recent study suggests that the amount of protein you need after a workout depends on the type of workout you do – whether you do a total body workout or work only a few muscle groups. For example, you might also need more protein if you lift at a high intensity, perform more compound exercises, or do a longer workout consisting of more sets or exercises.
Age may be another factor since studies show that older people frequently have some degree of “anabolic resistance” where their muscles don’t synthesize proteins as easily in response to a protein meal. So, protein requirements may be higher for a 65-year-old who lifts weights than a 30-year-old.
How much protein should you get after a workout? Based on this study, taking in more, 40 grams versus 20 grams, will maximize muscle recovery and protein synthesis. Whether you’ll get better results if you consume it within an hour of working out isn’t clear – but why not? Your muscles need glycogen replenishment as well. So, make you’re getting carbs and protein in about a 3 to 1 to 4 to 1 ratio.
Physiological Reports. “The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein”
Medical Daily. “Do People With More Muscle Require More Protein?” August 23, 2016
Scientific American. “How does exercise make your muscles stronger?”
Journal of the International Society of Sports Nutrition 2013. 10:53. doi:10.1186/1550-2783-10-53.
J Int Soc Sports Nutr 10.1 (2013): 5.
Exerc Sport Sci Rev. 2013;41(3):169-173.
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