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The Scientific Approach to Building Muscle


There are more than 600 muscles in the human body. Every day, these little contracting forces are hard at work, producing motion, stabilizing our bodies, and keeping our organs up and running. Though there are a few different types of muscle, the main type of muscle that the average gym goer is concerned with are called skeletal muscles.

Skeletal muscles, by name, are muscles that attach to our skeleton. The attachment sites are located on two or more different bones and are typically stretched across a joint. When the muscle contracts, it shortens, decreasing the angle between the bones and creating movement.

At the gym, the majority of us workout these muscles in hopes to build them up and make them grow. We lift weight after weight and trust that our bodies will take the necessary steps to produce bulging biceps and killer quads.

But how do muscles actually grow and is there any way we can be more effective and efficient about getting swole?

Let’s take a look at what SCIENCE has to say about the matter.

Muscle Anatomy

In order to understand the science behind building muscle, we must first understand the basic anatomical structures of a muscle.

This is a muscle:

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As you can see, a muscle is made up of groups of fascicles, which are made up of groups of muscle fibers, that are then made up of groups of myofibrils, which are finally made up of groups of filaments (actin and myosin). Phew! Basically, a bunch of strands are packed into groups, which are packed into groups, and then packaged into groups.

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A muscle contraction occurs at the filament level. The two different types of filaments (actin and myosin) run parallel to one another, only overlapping at the ends. When our brain sends the signal, a complex chemical reaction occurs and the myosin filaments reach out to the actin filaments and pull them, still parallel, toward the centerline of the myosin. This event causes the muscle to bunch up and shorten in length, contracting.

The Science of Muscle Trauma

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Hypertrophy, or the building of muscles, is a product of micro traumas that occur in the muscle fiber. When a muscle experiences damage or trauma, the muscle signals for back up in order to avoid death. The back up, in these cases, are satellite cells. These satellite cells flock to the area of trauma and fuse with the muscle in order to repair it. This fusion leads to an addition of mass in the muscle fiber because the satellite cells do not disintegrate. Instead, they provide the muscle fiber with additional nuclei and myonuclear domains. Due to the added substance, the result is a bigger muscle.

Traumatizing Muscle for Growth

So far, science has acknowledged three main ways, specific to hypertrophy, in which a muscle can experience trauma and distress:

  • Mechanical Tension- The repetitive act of concentric and eccentric contractions keeps a muscle under continuous tension. This mechanically induced tension leads to a swelling in the muscle cells (a “pump”), which disturbs the integrity of the skeletal muscle. When this occurs, the cell interprets the swelling as trauma and sends for back up.

  • Muscle Damage- The actin and myosin form the contractile segment of a muscle, which is also known as a sarcomere. Within a muscle are many sarcomeres that differ in measurement. When the muscle is lengthened, the weakest sarcomeres become damaged and this produces a shearing of myofibrils. The trauma initiates the hypertrophy process.

  • Metabolic Stress- Metabolic stress manifests as a result of exercise that relies on anaerobic glycolysis for ATP production. Simply put, metabolic stress is a result from short bursts of exercise, approximately 30 to 50 seconds. The product of anabolic glycolysis is a buildup various metabolites (lactate, hydrogen ions, inorganic phosphate, creatine, etc.). The acidic environment leads to muscle fiber degradation and activates the satellite cells.

Building Muscle with Science

Once we understand the reparative process of hypertrophy and how specific trauma can initiate this sequence of events, we can alter our training methods and modify them to optimize muscle growth. Here are a few techniques that promote muscle growth because they incite one or all of the factors that activate hypertrophy in muscle:

  • Eccentric Training- A significant amount of research has been completed over the topic of eccentric training. Despite the different types of eccentric training, they have all been shown to produce great gains. Focusing on the negative portion of an exercise stimulates hypertrophy. Move quickly through the concentric phase of an exercise and slowly in the eccentric phase.

  • Drop Sets- There are countless variations of drop sets. For example, doing 8 repetitions of dumbbell lateral raises with 35 lb to failure and then put the dumbbells down and complete 8 repetitions with 25 lbs to failure and then drop to 8 repetitions of 15 lbs to failure. Depending on the exerciser, a sequential drop of 10-25% in weight is appropriate with this technique.

  • Super Sets- Super sets are any two sets that are performed back to back without rest between exercises. It varies on preference but a super set could include agonist/antagonist (biceps curl and triceps extension), opposite action (chest fly and seated row), upper body/lower body (chest press and leg press), lower body only (lunge and heel raise), and upper body only (fly and chest press).

  • Cluster Sets- A cluster set is a set with built-in intraset rest periods that allow for more reps. For example, a typical 5 rep set would have you lifting a weight at your 5 rep max. A cluster set would have you lifting at your 5 rep max but then have you do two reps and pause, do two reps and pause, do two reps and pause for a total of 6 reps or more at your 5 rep max.

  • Alternating Rest Periods- Typically, there are three main rest periods that are utilized in resistance training: short (30 seconds or less), moderate (60-90 seconds), and long (3 minutes plus). Shorter rest periods have been shown to cause a significant amount of metabolic stress while longer rest periods with heavier loads have been shown to produce mechanical tension. By alternating rest periods, we can create both types of trauma to a muscle to promote hypertrophy.

Final Thoughts

Our muscles are amazing. If we can traumatize our muscles in specific ways we can force them to grow as an adaptation. To make the most out of our workouts, it is important to focus on exercises and factors that cause mechanical tension, muscle damage, and/or metabolic stress. In this post we have provided a few different training methods but hypertrophy is not limited to just these. Playing with variables like volume, intensity, repetition speed, and more can also cause trauma to the muscle fibers, leading to an increase in muscle size. In the end, though, there’s no doubt about it. When it comes to getting swole, science gains means SIZE gains!

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