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Muscle Protein Synthesis: The Payoff from Working Out with Intensity

Muscle Protein Synthesis: The Payoff from Working Out with Intensity


What is it?

Intense exercise, particularly when it involves resistance training such as weightlifting, breaks muscle proteins down into the amino acids they’re made of. That process of muscle protein degradation, or muscle loss, is known as muscle protein breakdown (MPB). But during exercise, MPB stimulates a natural, counteracting metabolic process called muscle protein synthesis (MPS), which creates new protein to repair the damaged muscles. As such, MPB must occur before MPS can. Intense exercise always stimulates more MPS than MPB, resulting in muscle growth, or hypertrophy.



What happens when MPS and MPB are equal?

Basically, nothing. When your MPS and MPB balance out, you’re simply in a state of homeostasis, or equilibrium, meaning that you’re neither gaining nor losing muscle mass. The difference between MPS and MPB is called your net muscle protein balance (NBAL). If it’s positive, it means your MPS is greater than your MPB and you’re building more muscle. The reverse is true if it’s negative.

Note that low-intensity exercise typically does not cause muscle damage and will not stimulate MPS. This is why people who leisurely work out don’t develop bigger muscles, although they might achieve small gains in strength and muscle endurance by doing so. Therefore, if you want to become more muscular, the key is to work out with relatively heavy weights and resistance and embrace the discomfort that comes along with it. In fact, the greater the intensity of your workout, the more it stimulates MPS. As a guidepost for weightlifting, lifting less than 40% of your 1-rep max is unlikely to increase your MPS. (Leal, 2022) The old adage "no pain, no gain" is the truth about improving your physique.



Can you intentionally increase MPS relative to MPB?

Yes, you can. As explained, MPS occurs naturally inside your body as a result of strenuous exercise and resistance training in particular. However, even though it’s a natural process, you can increase it by training harder and, more specifically, by applying the principles of progressive overload:

1. Volume (increase the number of reps and sets)
2. Intensity (increase the weight or the time under tension)
3. Density (reduce rest time between sets)
4. Frequency (work out more frequently)

In addition, consuming protein after an intense workout feeds MPS by providing a source of amino acids that bind to your skeletal muscle proteins. A good rule of thumb is to consume 0.3 grams of protein per kilogram of body weight within an hour after a workout. (ISSA, 2022) But it’s also true that a good workout will sensitize your muscles to amino acids for at least the next 24 hours. So consuming protein any time within 24 hours after your workout is likely to contribute to synthesizing more proteins that increase your muscle mass. (Oliver C. Witard, 2022)



Not to be confused with the "pump.”

Keep in mind that the hypertrophic effects of MPS are generally not visible from one training session to the next. When you experience hyperemia, or the “pump,” during and immediately after a workout, it’s just the sensation of your muscles swelling due to increased blood flow to the muscle group(s) you’re working out at the time. It is not the actual repair and growth of skeletal muscle tissue, which is what MPS does. MPS is a lagging indicator of intense training, and you must train consistently over a period of weeks or months before changes in muscle mass become noticeable to the naked eye.




ISSA. (2022, December 2022). Muscle Protein Synthesis: What It Is and How to Maximize It. Retrieved August 8, 2023, from www.issaonline.com: https://www.issaonline.com/blog/post/muscle-protein-synthesis-what-it-is-and-how-to-maximize-it

Leal, D. (2022, October 17). Is Muscle Protein Synthesis the Same as Growth? Retrieved August 08, 2023, from verywellfit.com: https://www.verywellfit.com/muscle-protein-synthesis-and-muscle-growth-4148337

Oliver C. Witard, L. B. (2022). Making Sense of Muscle Protein Synthesis: A Focus on Muscle Growth During Resistance Training. Human Kinetics, Inc. International Journal of Sport Nutrition and Exercise Metabolism. doi:https://doi.org/10.1123/ijsnem.2021-0139


*This newsletter has not been authored in whole or in part by any artificial intelligence tools.
*No content on this site, regardless of source or date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.


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