Most people are familiar with the relationship between rep ranges and the targeted effects they have on the body during strength training. The heaviest load that can be lifted at a given weight correlates with the maximum forceWhile anything you can do over 20 times or more clearly means muscle endurance.
However, somewhere between these two ends of the spectrum lies muscle hypertrophy. Some coaches and coaches claim that ten reps is the magic number, while others believe a range of 8-12 is more accurate. So what is it Will I grow a huge biceps if I do 4 sets of 8 or 3 sets of 12?
In all honesty, it doesn't matter, there is no magic window and the answer is more complicated than you think.
How do you gain muscle?
While you may be scratching your head and wondering why rep ranges aren't as important to building muscle as you previously thought, it's important to understand how muscle hypertrophy occurs in the first place.
There are three ways in which one can improve muscle protein synthesis via the mTOR pathway, which results in increased muscle cross-sectional area
- The first path is through increased muscle tension created by using a heavy load while performing an exercise over the entire range of motion. As a muscle spends more time under a certain weight, and then the load increases, the time under tension (TUT) increases. 2 By using slower paces, rest periods, and increased weight, the TUT can be increased dramatically for a given exercise.
- The second method of increasing muscle hypertrophy is through muscle damage, most often associated with severe pain or delayed muscle soreness (DOMS) that is felt several days after a tough workout.2 This pain is due to small microcracks in the muscle itself, particularly on the fibers for eccentric and concentric muscle contractions. If enough time is given for recovery and proper nutrition, The muscle fibers repair themselves and allow one to handle a slightly more significant stimulus next time.
- The third method by which muscle hypertrophy occurs is through metabolic stress. This strain is often associated with the use of lighter weights for a higher range of reps, and is associated with the burning sensation felt when lifting.2 As the muscles contract and relax continuously, blood build-up and swelling of the muscle cells occur. 1 This metabolic stress restricts blood flow and ultimately induces muscle hypoxia, which in turn enables metabolites such as lactate and hydrogen ions to be built up. These metabolites induce an anabolic effect that leads to molecular cell signals for increased hormonal responses in the body.
Each of these three methods play against each other and should be used in a complementary manner in order to achieve the best possible training results.
What matters
Understanding what drives muscle hypertrophy from a physiological perspective easily explains why subscribing to any rep range is not optimal for exercise.
By manipulating the three aforementioned variables, the volume load you exercise with can be controlled. This is possibly one of the most important considerations when looking for muscle hypertrophy.
Volume load is a simple formula that you can calculate as:
Sets x repetitions x loading = volume loading
Increasing the volume exposure through a properly periodized program will ensure that the body is stimulated more and ultimately it adapts.
For example, take the aforementioned number of reps / sets of 4 x 8 or 3 x 12. If I were to lift 4 sets x 8 reps x 100 lbs, that would be 3,200 lbs versus 3 sets x 12 reps x 100 lbs 3,600 lbs .
My 3×12 would probably give more significant results if all things were the same like Tempo and TUT because it's a bigger stimulus.
Now imagine if I did 4 sets x 8 reps x 150 lbs = 4,800 lbs, versus 3 sets x 12 reps x 120 lbs = 4,320 lbs. In theory, my 4 x 8 would be better for muscle hypertrophy.
You can see that the rep range is just one factor in the equationThis means that increased volume load can be achieved in a number of ways without actually having a magical repetition area.
What is interesting, however, is that anywhere in the range of 8 to 12 reps still seems optimal for inducing muscle hypertrophy because it finds a balance between moderate weight and a reasonably high rep range
Trying to do 50 reps at 10 lbs will only result in a volume load of 500 lbs, while 5 reps at 100 lbs can get the same result in less time.
Conversely, it would take 10 sets of 1 repetition at 300 pounds to reach 3,000 pounds.
In contrast, 3 sets of 10 reps at 100 lbs would equate to the same volume load, although a much longer rest period between sets would be required for each set of 300 lbs.
However, keep in mind that this is related to muscle hypertrophy. Volume loading is required for muscle strength, but it doesn't play nearly the same role as it does for muscle building.
Plus, there's only so much volume that you can process before insufficient recovery. That's another article for another day.
All in all, I hope you have a better understanding of how muscle hypertrophy occurs and how to manipulate your workouts. You can't get stuck in a dogmatic routine after doing an arbitrary number of repetitions just because you always thought it was best.
Doing a little research and looking for deeper answers is essential if you really want to understand how training works. Thanks for reading, as always.
References
1. J. Jones E., Bishop P, K. Woods A., and Green J. "Cross-sectional area and muscle strength: a brief review." Sports Medicine (Auckland, NZ) 38: 987-8. 994, 2008.
2. Hornsby WG, Gentles JA, Haff GG, Stone MH, Buckner SL, Dankel SJ, Bell ZW, Abe T and Loenneke JP. "How does muscle hypertrophy affect strength and athletic performance?" Strength & Conditioning Journal 40: 99- 111, 2018.
3. Loenneke J. P., S. Dankel, Z. Bell, S. Buckner, K. Mattocks, M. Jessee, and T. Abe. "Is Muscle Growth a Mechanism for Increasing Strength?" Medical Hypotheses 125, 2019.