Why doe muscle size does not necessarily correlate with muscle strength?

Question

As the title says. Why does hypertrophy (growing muscle tissue in size) does not correlate with the strength of the individuals training for strength (as in heavy weight lifting, without growing muscle tissue)?

In: 460

Answer 1

Edit: this answer is too technical for ELI5, but I’m leaving it intact for anyone who cares to read it.

TL;DR: hypertrophy prioritizes making an exercise inefficient in order to cause more stimulus to the target muscle. Strength prioritizes making an exercise efficient in order to maximize the amount of load that can be lifted.

Muscle size DOES increase strength, but not by as big of a margin as other factors. The two main principles in play are sarcoplasmic vs myofibrillar adaptations. Hypertrophy prioritizes both, but strength only prioritizes myofibrillar adaptations.

Sarcoplasmic fluid increases muscle volume, but not necessarily strength. Strength is dependent on the quantity of myofibrils within each myocyte (the makeup of a muscle fiber), and your body’s ability to recruit those units. Which means the more myofibrils each muscle fiber contains (stronger contractions), and the more practiced you are at recruiting them (motor skill and nervous system adaptations), the stronger you’ll become.

Hypertrophy is achieved by increasing the volume of work, which can be done with a dozen different tactics. Hypertrophy also doesn’t care about motor recruitment beyond being able to go close to failure without technique breakdown. Which means a variety of exercises throughout the week can stimulate the muscle in multiple different ways.

Maximal strength can ONLY be achieved by increasing load. If you’re not adding weight over time, your maximal strength will not increase. This means that whatever movement you want to get stronger at needs to be practiced consistently with minimal variations throughout the week. This maximizes nervous system and motor skill adaptations.

When it comes to myofibril quantity within each myocyte of a muscle fiber, it will increase size by a little and strength by a lot. But each muscle fiber can only contain so many myocytes, and each myocyte can only contain so many myofibrils. At some point, you’ll plateau and need to increase muscle size to make space for more myocytes to form.