The topic of protein synthesis as it relates to muscle building, is extremely important because It tells us exactly how frequently natural lifters should train if they want to build muscle at an optimal rate.
Research reveals that when you train a body part, protein synthesis remains elevated generally no longer than 48 hours. In most cases, it is elevated approximately 36 hours, after which, it returns back to a baseline level. This science is not "new" news either. We have known this scientific reality for decades.
What does this mean from a practical standpoint? An individual muscle will only "grow" during this protein synthesis window. So, if you use a body part split, you are repairing and rebuilding for up to 2 days and giving that muscle 5 days off each week. Though this will build muscle, it won't lead to optimal muscle growth rates. You can bomb, blast, blitz, and annihilate your muscles into extended periods of muscle soreness, but this will not extend the protein synthesis window. This notion that "more" soreness equates to "more" growth is off base. A muscle can experience growth without undergoing any noticeable degree of muscle soreness.
A study published in The Journal of Physiology looked at two different groups - one undergoing ES, or electrical muscle stimulation, and a second group undergoing voluntary muscle contractions. The DOMS experienced by both groups were fairly equal. What this study revealed was that muscle soreness was the result of extracellular matrix inflammation, which is the connective tissue that binds muscle fibers together. 1
So DOMS does not appear to be an indicator of muscle soreness or muscle tissue damage, but rather pain derived from connective tissue inflammation. Therefore, training for soreness is a misguided concept. To grow, we need to experience more muscle protein synthesis and make sure this surpasses the level of muscle protein breakdown. It would also make sense to make sure we maintain a heightened level of muscle protein synthesis as much as possible.
Protein Synthesis and Optimal Training Frequency
As we have established, you can have DOMS in a muscle without it currently being in a state of protein synthesis. Take German Volume Training for example. I experienced mind-numbing muscle soreness for 8 days after a GVT squat session. Despite this, my quads were only in a state of protein synthesis for up to 48 hours.
The obvious question in all this becomes: how then should we train for optimal muscle growth?
The answer: with a greater training frequency.
Instead of bombing a muscle group each day with endless volume, you are better off targeting muscle groups several times per week with a smaller amount of volume per day. By training a muscle group 2-3x per week with a more moderate volume, you will experience a greater degree of weekly protein synthesis per muscle group, and as a result, more optimal gains.
Why Are Body Part Splits So Popular?
For a very long time, bodybuilding magazines controlled the information given to those seeking to build muscle. Because of this, natural lifters began to emulate the body part splits being used by top IFBB pros. What you aren't told is why these workouts are effective for "enhanced" lifters, and why they won't be as beneficial for natural trainees.
Enhanced lifters maintain elevated protein synthesis levels through the use of insulin and other anabolic drugs. You rarely hear this discussed on forums or in magazines, but it is the reality of the situation. People tend to only discuss the topic of steroids when it comes to bodybuilding, but the chemical soup being used is far more than simply steroids.
By using insulin (and other drugs), a lifter can maintain elevated protein synthesis levels, therefore negating the need to train a muscle frequently. The added recovery benefits they receive from steroids (and other chems), along with the increased receptor stimulation that comes from intense contractions, which could be derived from volume training, makes a body part split a "natural" choice for non-natural bodybuilders.
Full Body Workouts Lead to Optimal Gains
I know what you're thinking. You've met plenty of guys who made quality gains using body part splits. They certainly did! The point of this article isn't to tell you that gaining on splits is impossible. It is obviously possible. In fact, guys can make very good gains on body part splits.
The question though is this: are these gains optimal? Generally not. If you are only experiencing protein synthesis for up to 48 hours each week per muscle group, there is still some optimization that is possible. Let's look at an example.
Let's say that Lifter A is using a body part split, and Lifter B is using a full-body workout or upper/lower split. We will also pretend that all things are equal: training consistency, diet, supplementation, rest, etc.
During his first 3 years of training, Lifter A, Mr. body part split, experiences the following muscle gains:
- Year 1 - 14 pounds of muscle
- Year 2 - 7 pounds of muscle
- Year 3 - 3.5 pounds of muscle
Lifter B on the other hand might experience the following gains, which are a tad bit more optimal:
- Year 1 - 16 pounds of muscle
- Year 2 - 8 pounds of muscle
- Year 3 - 4 pounds of muscle
When Lifter A posts his body transformation pictures on the web, it is jaw-dropping! He looks amazing and appears to be making optimal results. 24.5 pounds of muscle is a huge amount and changes his physique dramatically. But, it was not optimal.
If he would have gone the route of Lifter B, maximizing his protein synthesis by elevating it every 48 to 72 hours with a new workout that is re-targeting the same body parts, his gains would have been even more impressive.
Now obviously the above examples are just that - examples. The numbers provided are not expectations for everyone, though they are realistically based on the gains curve and how natural muscle building works from year to year.
Natural lifters tend to experience a decrease of gains by about half per year, give or take. This can certainly vary if someone is starting underweight, or did not experience near-optimal gains during their first several years of training.
How Frequently Should You Train?
If you want to build muscle as rapidly as possible, consider switching to a full-body workout. By targeting each muscle group 3 times per week, you will keep protein synthesis levels higher, on average, which will lead to more optimal gains.
For intermediate lifters who have already built a quality amount of strength, training on an upper/lower split might be a better option. Heavy weights can take their toll on joints and connective tissue, so a few extra days of rest per week might be beneficial.
Whatever you do, don't rush into a full-body workout using a ton of volume. Frequency training is a completely different beast. The point of full-body workouts isn't to cram in a ton of body part volume per day. Instead, you will hit each body part with a moderate to lower set volume and train it more frequently.
Many guys fail to make the transition into full-body training simply because they try to do too much each day. Start with a lower amount of volume and evolve your training by adding more sets if you feel it's necessary. I recommend 3 to 5 sets per day for larger muscle groups, and a max of 6 to 9 weekly sets for smaller muscle groups.
Some of you will simply not like full-body work. If this is the case, stick to body part splits. You are going to see far better results in doing something you like than using a training style you hate.