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3 Mechanisms of Maximal Muscle Growth

Scottsdale Personal Trainer

So you’re trying to maximize your gains and get jacked, ripped, shredded, freak-beast: whatever- unfortunately most people don’t understand the principles of building bigger muscles. To keep it simple if you want bigger muscles, you’ll need to get stronger. And if you want to get stronger you will need to provide a stimulus that progressively overloads the system so that you place a greater amount of stress and tension on a muscle over time. So heavier weights, means more tension, which means bigger muscles. Right? Not quite.

If heavier weights were the only determining factor that influenced the size and growth of a muscle than bodybuilders would be runts in comparison to powerlifters and strongmen athletes, who place much greater tension on their musculature due to the intensity of the loads they use. This is simply not the case and it’s because there are several other factors at play.

There are three mechanisms of hypertrophy:

  • Mechanical tension

  • Metabolic stress,

  • Muscle damage

If you neglect any one variable, then you’re gain making ability.

1. Mechanical Tension: Lift Heavy!

Mechanical tension equates to total muscular force. Simply just means pick heavy stuff up, near failure, between 3-8 reps. When you place tension on a muscle by stretching it passively, the source of tension is called passive elastic tension. If you place tension on a muscle by flexing it as hard as possible via an isometric contraction, the source of tension is known as active tension. When you lift weight through a dynamic full range of motion, you illicit both passive and active tension which produces the greatest force possible.

You might think that the heavier you lift, the more mechanical tension. That's true only to a certain extent. For example, a 2013 study by Pinto, et al. found that muscle activation in an isometric bench press task topped out at 90% of maximal voluntary contraction.

This is partially due to the time under tension (TUT) which is another important factor to consider. Performing one rep maxes continuously each session will not provide enough of a stimulus to optimize anabolic processes. The muscles need ample signaling to grow larger.

Most lifters have an optimal intensity below the one-rep max for which mechanical tension on the targeted muscles is at its highest. Adding additional weight won't increase mechanical tension and may actually shift it away from the desired muscles and onto passive structures or other muscles.

For an intermediate to advanced lifter, peak mechanical tension will be elicited around 75-90% of a one-rep max for reps of 3-8 near failure.

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Best Exercises for Max Mechanical Tension

  1. Squats

  2. Bench Press

  3. Deadlift

  4. Military Press

  5. Pull Ups

  6. Hip Press

  7. Rows

Training Parameters for Max Mechanical Tensions

Sets 3-8 Reps 3-8 or 5-12 (depending on the lifter and the lift) Tempo 2/0/1/0, 2/0/1/3, or 2/3/1/0 Rest 2-3 minutes

2. Metabolic Stress: The Pump

Ahh the glorious pump! turns out Arnold was on to something. Metabolic stress is the burning sensation you feel as your working muscle becomes engorged with blood. Metabolic stress is induced by several physiological factors which contribute to a hypertrophic effect.

  1. Arterial blood pooling and occlusion of venous return from constant muscle contraction (Blood gets trapped)

  2. Cellular swelling and satellite cell signaling due to pooling of blood

  3. Hypoxia or lack of oxygen in muscle

  4. Accumulation of metabolic byproduct such as lactate and increased flow of anabolic hormones to muscle.

The key to achieving metabolic stress is to keep constant tension on the muscles by maintaining a continuous cadence (no rest between reps) and reversing direction just short of lockout or just before bottoming out.

This way, as blood gets pumped into the muscles by the arteries, the steady muscular contractions will prevent the veins from letting blood escape, resulting in high levels of metabolic stress and cell swelling.

When training for the pump, take sets to momentary muscular failure for moderate to high reps with short rest periods in between.

Best Exercises for Metabolic Stress

  1. Pec deck/Cable Crossover

  2. Pullover machine

  3. Rear Delt Raises

  4. Leg extension

  5. Leg curl

  6. Back extension

  7. Barbell glute bridge

  8. Lateral raise

  9. Concentration curl

  10. Rope tricep extension

Training Parameters for Metabolic Stress

Sets 3-4

Reps 12-20+ (to momentary muscular failure)

Tempo 1/0/1/0 or 2/3/1/0

Rest less than 1 minute

3. Muscle Damage: Negatives!

Structural muscle damage is identified by muscle tissue breakdown and occurs in the muscle membrane. This creates an inflammatory reaction from the immune system which produces delayed onset muscle soreness (DOMS) felt after most weight training sessions. Muscle damage It's created by slow eccentric contractions, extended range of motion, and high tension in the stretched position of the muscle. Movements that place the greatest tension at long muscle lengths (in a stretched position) are best suited for creating muscle damage.

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Best Exercises for Muscle Damage

  1. Olympic Squats

  2. Deficit Deadlifts

  3. Dumbbell Presses

  4. Chest flies

  5. Pullovers

  6. Lunges

  7. RDLs

  8. Good mornings

  9. Incline dumbbell curls

  10. Overhead cable tricep extension

Training Parameters For Muscle Damage

Sets 2-5 (depending on training frequency) Reps 8-12 Tempo 4/0/1/0 Rest 1-2 minutes


Until more research is done on mitigating what contributes most significantly to muscular hypertrophy, you should aim to optimize your training by incorporating a variety of rep ranges, intensities and exercise selection so that you can reap the benefits from all 3 mechanisms of muscle growth. Start by creating an organized, periodized program, then aim to get stronger through progressive overload. Start with heavy mechanical tension based compound exercises that require the most from the CNS, then move into pump work as your workout progresses.