Our bodies are complex things. The reality of the situation is that we truly don’t know, as an exact science, the specific steps we should take to build muscle. What we do know is a few general principles, when incorporated into a training program, lead to muscle growth in most people, most of the time – mechanical tension, metabolic stress, and muscle damage.


Mechanical tension ought to be looked at as simply the force that gets applied to a muscle. There’s two types of mechanical tension:

ACTIVE TENSION – when tension is placed on a muscle via contraction

PASSIVE TENSION – when tension is placed on a muscle without a contraction (i.e. the muscle is being stretched)

An example of these in practice using a dumbbell curl: when you begin to raise the dumbbells in a curl your bicep muscle is experiencing active tension. Once you begin to lower the dumbbells back down your biceps are experiencing passive tension because there’s still tension on the muscle itself but you’re no longer contracting them. As a result, performing any movement through a full range of motion involves both active and passive tension.


  • Add more:
    • Weight
    • Reps
    • Or both
  • Mind-muscle connection 


If you’ve ever performed a lot of reps of a movement and really pushed yourself, you probably felt a bit of a burn in the muscle you were using. That burn is pretty much the result of metabolic stress.

In practice, metabolic stress occurs after a series of steps:

  1. When we contract our muscles, our veins become blocked
  2. Blood is no longer efficiently able to escape the muscle
  3. Hypoxia (or a lack of oxygen supply) begins to occur as new blood isn’t able to replace the oxygen deprived blood
  4. Metabolic by-products begin to be released within the muscle
  5. Cells begin to swell as fluid is pushed into them (which often gives people that “pump” during and after a workout)


  • Performing lots of reps really fast
  • Short rest periods
  • Partial reps
  • Dropsets
  • Supersets
  • Mind-muscle connection


Muscle damage is exactly what it sounds like – we’re essentially breaking the muscle. The current idea behind this is that when we tear our muscle down and follow it with adequate recovery/rest our bodies adapt by growing the muscle back stronger and bigger. This is much like your hand building a callus on your hand. The callus arises because it’s your body adapting to the stresses placed on your hand.


  • Increase the weight
  • Shorter rest
  • Slow movements down
  • Varied movements
  • Mind-muscle connection


No matter what you do when training, your body is going to experience each of the 3 mentioned principles; mechanical tension, metabolic stress, and muscle damage.

For example, a very heavy bench press that someone can only perform for 3 reps is going to produce a high level of mechanical tension, while metabolic stress and muscle damage is going to be relatively low. On the other hand, if someone were to perform a bench press with a weight that they could perform 20 reps with and actually performed those 20 reps it would produce a significant amount of metabolic stress and muscle damage (as displayed by the heavily increased heart rate as well as likely experiencing burn in the muscle) while the mechanical tension would be relatively lower.

Having said that, keep this in mind: include a bit of everything

As already mentioned early in the article, we don’t know exactly what works best but we do know that these things do work (for most people, most of the time).

Furthermore, there’s a hierarchy in which I would prioritize each variable as outlined below:

Focus on first building a solid base with mechanical tension before actively focusing on the next steps of the pyramid

Over time, assess what works best for you. It’s completely plausible to think that some people will respond better to some things compared to others. The best way to find out what works best for you is experience and being aware of your training and progress.


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