Leveraging the Mechanisms of Hypertrophy for Better Workouts

Whether you're training a high school athlete or soccer dads, at some point or another, muscle hypertrophy will become a major training target, and rightfully so! Carrying more muscle mass allows you to produce more force, makes you harder to push around on the field, increases confidence, and has a pretty cool side-effect of making you look good in a swimsuit. So yeah it's kind of a big deal!

So what's the ideal way to train for hypertrophy? Well, it gets complicated. Like anything in the field of strength and conditioning, there is no "ONE WAY" to achieve any training target. However, this doesn't mean that anything and everything will get you the results you want. Your training must be guided by principles and intelligent progression in order to get best results.

The main principles that you’ll want to take into consideration are the actual mechanisms or causes of muscle hypertrophy, of which 3 seem to play the largest roles: mechanical tension, metabolic stress, and muscle damage.

First, let’s figure out what each is individually so we can determine our best avenues for targeting them.

Mechanical tension refers to the actual physical stress placed on the muscle from both internal and external forces. When it comes to mechanical tension, load is the name of the game. This is where the traditional minimum 60-65% of 1RM value comes from (although this is not necessarily true, as you will see why in the next section). The greater the load, the more mechanical tension is placed upon the muscle. However, a sufficient volume of mechanical tension is required for optimal muscle hypertrophy. This is why training at near maximal weights, which provide a very large amount of mechanical tension on a per rep basis, does not tend to result, directly and solely, in large amounts of muscle hypertrophy. Generating enough volume at this intensity is hard to do and extremely fatiguing, which is why it is generally best to combine moderate to high loads with moderate volumes (3-5 sets x 6-8 reps is a good place to start).

Metabolic stress refers to the physiological stress undergone by the muscle at a cellular level. With metabolic stress, volume and short rest periods are your friends. When you think of traditional bodybuilding methods used to chase the “pump” these are really creating large amounts of metabolic stress. These don’t require high loads, simply high volume and short rest periods. An example of a set rep scheme may be 3 sets of 15 with 30 second rest periods. Set-rep-rest schemes associated with metabolic stress need to be anaerobic-lactic or glycolytic in nature, via set duration (roughly 8-20 reps) and incomplete rest periods (<45 sec) in order to cause a build up by-products in the blood. This build up leads to a change in osmotic pressure and forces fluids into the cells that surround capillaries. This swelling, is the “pump” you feel. Besides making you feel invincible and want to walk around the mall, this cell swelling threatens the integrity of the cell enough for the cell to signal for backup and increase protein synthesis.

Finally, muscle damage may potentially serve as mechanism for muscle hypertrophy. Muscle damage is fairly straightforward and refers to the microtraumas created in muscle fibers. This damage is inflicted primarily during the eccentric phase of an exercise and is why concentric-eccentric exercises outperform isometrics for hypertrophy when all else is equal. Longer eccentrics of 3+ seconds with sufficient load and volume will create a fair amount of damage. Be careful, however, when programming with this as your target because muscle damage also leads to delayed on-set muscle soreness (DOMS) and can hinder volume and intensity of the following workouts. So keep this in mind when writing your programs!

So now that we have the principles, how can we put them together? Now it's not absolutely necessary to hit all three mechanisms in the same workout, especially if hypertrophy is of secondary importance and your time is better spent elsewhere, but try to hit at least two. This actually much easier to do than you may think. In fact, mechanical tension and muscle damage can often be accomplished with the same exercise using moderate loads and reps with slow eccentric phases (you can also use this combination to target relative strength). My recommendation is to go after metabolic stress towards the end of the workout as you'll be working at or near failure and will have a difficult time using heavy enough loads to target mechanical tension after. Plus you can leave and go straight to the mall with a sick pump!

Below is an simple example of how these strategies may be used together during a workout.

1A Trapbar Deadlift 3-4x8 w/ 3 sec eccentrics

1B.BB Bench Press 3-4x8 w/ 3 sec eccentrics

**Full rest period to allow for heavier loads to be utilized--> increased mechanical tension for strength and hypertrophy

2A. RFE Split Squat 2-3x12 each

2B. 1 Point DB Row 2-3x12 each

**30 sec rest between exercises

3A. DB Curls 3x15

3B. Tricep Pushdown 3x15

**No rest between exercises or rounds

1A&B: Main work Target: Mechanical Tension/Damage

2A&B: Secondary work Target: Metabolic Stress

3A&B= Direct arm work Target=Metabolic stress

Its important to note that mechanical tension and metabolic stress lie on 2 ends of a continuum rather than 2 sides of a coin. This workout shifts from mechanical tension side of things to metabolic stress side as you move through the workout.

Again this is just one example of how these principles can be used. Now that you understand the building blocks you can now manipulate them as you please and are limited only by your creativity.

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Schoenfeld, B. J. (2010). The Mechanisms of Muscle Hypertrophy and Their Application to Resistance Training. Journal of Strength and Conditioning Research, 24(10), 2857-2872.

Schoenfeld, B. J. (2012). Does Exercise-Induced Muscle Damage Play a Role in Skeletal Muscle Hypertrophy?. Journal of Strength and Conditioning Research, 26(5), 1441-1453