Mechanical stress as a stimulus for muscle hypertrophy

Author: Mikhail Ziborov - author of the site makefitness.pro.
2023-04-13

The eternal debate: what is better for muscle mass growth – heavy weights or high repetitions? After all, both bodybuilders and powerlifters, who work on different principles, do not significantly differ in muscle size and mass.

We regularly address this question (and many others) in our Telegram channel yourfit. There, you can calmly ask any questions that interest you, and we will discuss them.

What is Mechanical Stress for Muscles?

Mechanical stress (also called mechanical load or mechanical tension of the muscles, mechanical tension) is the stress that your muscles experience during strength exercises (with weights, body weight, etc.).

Muscles experience mechanical stress when they contract (the concentric phase or the phase of lifting the weight) and also when they stretch (the eccentric phase or the phase of lowering the weight).

Mechanical tension in muscles is one of the key factors that trigger muscle tissue growth (some scientists and trainers consider it the most important factor).

Additionally, other factors contributing to muscle tissue growth include muscle damage and metabolic stress, which, according to some, can also promote muscle growth independently, although they are slightly less effective than mechanical load.

How to Create Mechanical Tension in Muscles

The greatest mechanical load is placed on muscles that lift maximum or submaximum weights (i.e., those that are difficult to handle from the first repetition). By the way, heavy weights recruit almost all muscle fibers for the work right from the first repetition, unlike moderate and light weights, which recruit fibers as the previous ones become fatigued.

Lifting heavy weights signals cells to initiate recovery processes (protein synthesis). This way, satellite cells grow and divide, providing building blocks for damaged muscles. In short, after working with heavy weights, your muscles recover and become bigger and stronger. You probably already knew this.

Notice! Mechanical tension increases with the number of phases of movement included in the exercise. For example, many beginners neglect the relaxation phase (eccentric phase):

• When doing pull-ups, instead of lowering themselves, they just relax their arms and fall;
• When bench pressing, they don’t lower the barbell to their chest properly and let it drop by relaxing their arms;
• When squatting with a barbell, they don’t squat under control but let their legs relax and drop down.

There are many such examples. But the most important thing is that in this way, beginners deprive themselves of part of the mechanical stress that could positively impact their muscle growth.

In the long run, to ensure that your muscles continue to grow, mechanical stress needs to be maintained at a consistent level. The body adapts to workloads and this stress, and if you train for a long time with the same weights, adaptation to mechanical stress will occur, and it will stop triggering muscle growth.

Therefore, you need to maintain mechanical tension in the muscles. In simple terms, you should increase your working weights (here’s my article on How to Know When to Increase Weights).

How Not to Create Mechanical Tension in Muscles

Often, those who chase heavy weights take on too much, adding more to the bar than they can lift CORRECTLY. Technically correct. Performing an exercise with incorrect technique can pump your muscles, but it also carries side effects in the form of injuries (now or in the future) and the formation of improper movement patterns.

An article on whether you can build muscle with poor technique can be found here. You can find professionally designed training programs at the link (for free).

If you develop incorrect technique, at some point, you will be unable to effectively work with heavier weights, even if you do not sustain any injuries. For example, there are guys who bench press in a "chest style," spreading their elbows wide. While this way of bench pressing can effectively target the chest, they still want to work with heavy weights.

As a consequence, this leads to shoulder joint injuries, strains in the chest muscles, and a lack of significant progression in bench pressing. Some lighter lifters may significantly outlift a heavier athlete who uses "chest style" with wide elbows.

In general, do not lift excessively heavy weights to create the greatest mechanical tension.

Also, avoid using cheats. Not the principle of cheating, but rather cheating from the very first repetitions of the set. Cheating redistributes the load from the target muscle to others. Thus, mechanical tension in the target muscle decreases, which in turn means it grows less. Cheating is meant not to decrease the load on the muscle but to prolong the tension on that muscle.

For example, if you do 8 repetitions with proper technique (the muscles have already received mechanical tension) and then do 2 repetitions with cheating (the muscles receive even greater mechanical load).

To learn everything about repetitions, sets, and load cycling, visit our site makefitness. For high-quality sports nutrition from the manufacturer, go here.