So what is Muscle Protein Synthesis (MPS)?
Put simply, it is the process of building muscle mass. Through MPS we recover, rebuild and grow our muscles to adapt and become stronger.
MPS is directly stimulated by two different anabolic factors: exercise and protein intake.
Before diving into the two, we must first cover nitrogen balance and it’s relationship with MPS.
MPS or anabolic and Muscle Protein Breakdown or catabolic are the two different states that describe whether the body is building muscle or breaking it down. The two constantly fight over the state of the muscle which results in either a positive (anabolic) or negative (catabolic) nitrogen balance.
You might have guessed already that we want to keep a positive nitrogen balance, otherwise, our body breaks down the proteins and we lose muscle. This is where exercise and protein intake come in. Through these two anabolic factors, we can keep our body in a muscle building environment.
We begin with Exercise. The training factors that matter include the number of sets performed, number of reps per set, the amount of rest between sets, whether sets are taken close or to failure, and frequency of training.
- Number of sets
Multiple sets of a single exercise stimulate MPS to a greater extent than a single set. Most athletic associations include the NSCA & NASM recommend about 3-4 sets of an exercise if the goal is muscle hypertrophy.
- Number of reps per set
Rep ranges will range for each individual as it can depend on the individual’s fitness level. Novice lifters can stick around 8-12 reps consistently for 6 months or so and receive optimal MPS benefits. For more experienced lifters – such as those lifting consistently for a year or more – can experiment with wider rep ranges (1-15 reps) as long as it is in a periodized fashion.
- Rest between sets
For a novice lifter, rest periods should range between 90-120 seconds. Again, this will vary for more experience lifters where they must correlate their rest periods with the respective rep range they are attempting. For example, for lower reps such as 1-6 rest periods should range between 2-5 minutes. Where rep ranges on the higher spectrum will maintain a lower rest period closer to 1.5-2 min.
- Training to failure
Not every set should be taken to failure. A better approach is to perform multiple sets close to failure – with maybe 1-2 reps left in the tank – before attempting the final set to absolute failure. This way performance isn’t diminished too early in the training session. For novice lifters, training close to failure seems to yield same results as going to absolute failure.
- Frequency of training
MPS lasts about 72-hours post-exercise but peaks at about 24-hours. This means for maximal muscle growth, an individual should train muscle groups more than 1x per week.
Now onto Protein. Proteins aka amino acids are the building blocks of muscle. Think of them as the bricks in a wall. Every brick laid builds the wall higher and stronger.
- Protein Intake
Recommendations range from 1-1.5g/lb. of body weight for the general population. This varies more for high-level athletes as they need a high level of intake closer to 2g/lb. of body weight. Meals should include at least 20g of protein to kick-start the MPS process. Consuming closer to 40g can increase MPS by around 10-20%.
- The Amino Acid Leucine
The true factor behind protein intake and it’s ability to rebuild muscle lies within the amino acid profile, specifically Leucine. Leucine is an essential amino acid that is the most potent at inducing MPS. About 2.5g of Leucine is needed to trigger a chemical mechanism known as M-TOR that acts like a light switch at activating MPS. This is why 20g of protein – and possibly more – is needed because that amount contains the relative amount of Leucine.
- Animal sources vs. plant sources
Whey Protein is the greatest source of protein to induce MPS, this is mainly in part to it containing a large amount of Leucine. Whey protein is found mostly in animal sources but also supplementation. Plant sources contain little to no essential amino acids which means they must be consumed in large quantities or supplemented in order to stimulate MPS.
Insulin does not induce MPS, however, it does inhibit muscle protein breakdown even in small amounts.
In conclusion, both exercise and protein contribute to the anabolic stimulation of the muscle, which results in muscle growth. The research shows that acute variables should be reviewed to optimize MPS.
I hope this article has shed some light on the science and mechanisms behind muscle growth. Thank you for reading.
Trommelen, Jon. “The Ultimate Guide to Muscle Protein Synthesis”. Nutrition Tactics. 17, August 2016. http://www.nutritiontactics.com/measure-muscle-protein-synthesis/#6_1_Number_of_sets
Trommelen, Jon. “Perfecting Protein Intake in Athletes: How Much, What, and When? (and Beyond)”. Stronger By Science. 5, July 2017. https://www.strongerbyscience.com/athlete-protein-intake/
Born in South Florida and initially exposed to fitness training through the bodybuilding scene, Connor found his interest in fitness was less of a hobby and more of a lifestyle. This led him to study exercise science and sports nutrition at Eastern Connecticut State University and thereafter to become a Certified Personal Trainer.
Over the past few years, Connor has made training a necessity in his life. His workouts are taken as a time to reflect and test his mental and physical limits that continue to give him an edge to carry throughout his day.
Connor is currently the Head Trainer and Strength Coach at a private gym in Hartford, CT where he trains and educates his clients on the importance of fitness and nutrition for overall health. "
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