What promotes muscle growth?
This seemingly simple question is one that gets argued about endlessly online, and the exact mechanisms concerning why and from what muscle tissue grows is an ongoing area of study. I am not an in-the-lab scientist, though, and per my own training practice, I care about what I can APPLY, not what I can argue about.
Relative to the current body of knowledge, the following thesis best represents what I currently know about hypertrophy.
- Gravity is a universal force that affects every living thing. The ability to move is essentially an ability to resist gravity. Gravity is constant, and without muscle, we are weak to resist it.
- Resistance training is an amplification of gravity. Muscle growth, beyond the SAID principle, is an adaptation to the stressors of greater gravity/compression upon the skeleton. When you inhibit movement, an organism will adapt/evolve to lessen and overcome the inhibitor.
- Muscle produces force. The greater levels of force production possible, and the longer force can be sustained, the “stronger” that muscle will be. Gravity, hence some level of muscle, will always exist, even in untrained people.
- Muscle tissue can be damaged, and the majority of this damage comes from the eccentric phase of lifting. Recovery from this damage corresponds strongly with increased muscle growth. “Controlling the weight” is a good adage to follow.
- Muscle tissue comprises of different size of muscle fibers, commonly called motor units. Because muscle fiber composition is not uniform in regard to the size of the motor units, muscular fatigue is a sliding scale. A two-rep set does not fatigue all the motor units, only the largest. Higher rep sets fatigue more motor units. The most effective means of promoting muscle growth, then, are found in fatiguing as many of the motor units as possible within a given muscle. For this reason, “high reps” is an effective strategy.
- Muscle growth outpaces connective tissue (ligaments and tendons) growth and repair, as well as skeletal increases in bone density. For this reason, while a muscle could respond favorably to multiple low rep sets taken to fatigue, the connective tissue and bones will not be as quick to respond. Because of this, low rep training for hypertrophy, despite being “equal” in some aspects of the current body of research, will in practice often lead to inflammation, burnout, and/or injury. It is not a sustainable strategy and is best used in designated phases of training. Sustainably, higher reps are more reliable.
- Muscle growth seems to be promoted by “metabolic factors" (i.e., the accumulation within the muscle of waste products from repeated muscular contraction). This happens along with cellular swelling (hyperemia), commonly referred to as the “pump.” Hence, getting a “pump” and feeling the “burn” are useful measures of biofeedback that a muscle has been adequately worked in training, and an appropriate level of stimulus has been created.
- To achieve any of the above, the target muscle must have a level of innervation (mind-muscle connection) that facilitates its full recruitment relative to the movement being performed. A lack of innervation will hinder hypertrophy. Mind-muscle training then is not an esoteric concept, but rather a means of creating innervation through conventional and novel strategies within a target muscle.
- Muscles need oxygen because oxygen powers EVERYTHING. The greater the oxidative capacity of a muscle (how well and much it uses oxygen), the greater the hypertrophic potential. ATP powers muscle contraction, and production of ATP mandates oxygen. Without adequate oxygen supply, muscles will not be able to recruit and contract to the fullest possible effect. Cardiorespiratory development of the aerobic system is crucial for muscle growth, both at the central and local level. There is a reason bodybuilders have historically WALKED, and walked A LOT.
- Hormones and nutrients increase the magnitude of effect from training, but even in the absence of hormones and adequate nutrition, muscle growth can still happen. So long as the body can allocate energy from somewhere, muscles can grow, even in less than “optimal” conditions. While endogenous and exogenous hormones promote muscle growth (elevated testosterone levels increase LBM, even in the absence of resistance training) and adequate nutrition can do so as well (increase protein intake corresponds with increases in LBM, and overall bodyweight) only mechanical tension/resistance has “infinite amplitude” to promote hypertrophy. Weights can always get heavier and more reps can be always be done, as the overall “power” of stimulus is far stronger than drugs and/or food alone. Hormones and food may create the environment and add to the effects, but lifting is the single greatest “effector.” As a side note, if lifting and nutrition have been “maxed” out, all that is left is increasing the hormonal environment.
Conclusion in Application
- Muscle promotes movement and movement promotes muscle. Every living thing moves in defiance of gravity.
- The more muscular you are, the more you can defy gravity. Nature will reward this audacity with increased lifespan and greater overall quality of life.
- Resistance training is a formalized, systematic practice of defying gravity through different planes of motion.
- What goes up must come down. A fall doesn't kill you; it's the landing that does. Muscle breakdown doesn't come much from the “up." It's the "down" (the eccentric) that causes most of the damage.
- Movement possibility is infinite and ranges from very small to very large. The muscles evolved accordingly. The biggest muscles can defy gravity in the most obvious ways, the powerlifts being an operative example. The greater the defiance, and the longer duration the defiance, the larger the muscles. In contrast, the most complex, multi-planar movements are “articulate” movements that require sustained coordination. Coordination is the creation of patterns. Complex articulation and gross defiance are different sides of the spectrum. Dancers will never be the size of bodybuilders, and sumo wrestlers will never be gymnasts.
- High reps work, have always worked, and will always work. When in doubt, training within the 6-20 range will succeed more often than it will fail.
- If sustainably is not considered, any conclusions drawn will be inherently short-sighted. The faster an effect is created, the less sustainable the effect will be. The most effective means of growth will be mediocre when examined through the lens of only 12 weeks.
- Biofeedback is objective, the interpretation is what is subjective. Dismissal of biofeedback-driven ways of thinking (bro-science) is guilty of practicing non-scientific thinking. Science is a way of thinking to further understanding and observation, not a singular means of studying to prove “rightness.” Mind-muscle connection is real, as is chasing the pump.
- If you don't breathe you, you die. The dismissal and overall ignorance of oxygen’s role in muscle physiology is one of the glaring holes within the current paradigm of practitioners. The sheer fact that many disease states are characterized by a low oxygen environment should be reason enough to consider “cardio” as being of some importance to overall health, let alone muscle growth.
- No one builds muscle as fast as they would like, welcome to the club. Once “optimization” of the training stimulus and nutrition have been reached, the mediation of muscle growth comes down to hormones. More hormones = more muscle.