How do muscles grow?
If you read Part 1 of this series, you understand how important our hypertrophy programs are for better metabolic health, longevity, and quality of life. There are two main components of the hypertrophy equation:
| Stimulus Muscle damage, metabolic stress, or mechanical tension. | Recovery Adequate nutrition, sleep, and appropriate rest from and during training. |
- Stimulus: There are three hypothesized mechanisms of hypertrophy: Muscle damage, metabolic stress, and mechanical tension.
- If you’ve been in or around the fitness industry for long enough, you’ve likely heard that you must “break muscle down” when you’re working out in order to “build it back up” stronger. This would be the muscle damage hypothesis, which has been disproven by contemporary research. With advances in our ability to study hypertrophy, we’ve come to understand that not only is muscle damage not required for growth, it’s often detrimental to it.
- You may have also heard that the key to growth is getting a pump or “feeling the burn” in a given tissue. These notions comprise the metabolic stress hypothesis and while this doesn’t seem to be completely unimportant when it comes to hypertrophy, research is clear that it’s also not a requirement.
- By far the most proven mechanism when it comes to providing a hypertrophic stimulus is mechanical tension. Renowned researcher Brad Schoenfeld says, “Simply stated, mechanical tension can be defined as the stress applied to a muscle, generally (although not exclusively) from an external resistance. Resistance can be applied to the muscle in various forms including but not limited to free weights, cable pulleys, pneumatics, hydraulics, and body weight.” When we apply stress to muscle, the body senses the force that is required in order to overcome said stress, and this begins a cascade of events that eventually can lead to muscle hypertrophy so that you are more prepared to deal with the same stress the next time it is applied. The first step in driving muscle hypertrophy is applying a sufficient but not excessive amount of mechanical tension on a regular basis.
- Recovery: This is the step that is often forgotten in hypertrophy. We can provide the body with all of the stimulus to grow that we want, but if we are not providing it enough opportunity to recover, growth will be sub-optimal at best. Optimal muscle hypertrophy requires:
- Adequate nutritional intake
- Sufficient caloric intake: In order for us to grow tissue, we cannot be in a significant caloric deficit when we look at calories in vs. calories out. If your intake is significantly below your caloric output on a regular basis, you need not worry about details such as training volume or protein intake: you won’t grow without enough calories.
- Sufficient protein intake: Once you’re consistently eating enough calories, the next crucial element to building muscle is ensuring that you’re getting enough protein. We’ve covered protein intake in previous blogs.
- Rest: Sleeping a minimum of 7 high quality hours per night seems to be required for consistent hypertrophy. Sleep is covered in detail in this post.
- Intra-set Rest Periods: In order to fully recover from our training to maximize adaptation, we also must allow for adequate rest between sets. Research has shown that when we allow at least 2-3 minutes of rest between sets, we maximize our ability to generate mechanical tension.
- Adequate nutritional intake
Now that we’ve established the benefits of increasing muscle mass and the general requirements to promote growth, we will examine how we get there in Part 3 of this series.
