Muscle Hypertrophy

Muscle damage

Muscle damage refers to just that—actual damage caused to the muscle fibers by high levels of tension. This damage necessitates repair, and if the body is provided with proper nutrition and rest, it will grow the fibers to better deal with future stimuli.

What is muscle tissue?

Muscle tissue is a pretty complex structure, with bundles of long strands of muscle cells (known as fibers) sheathed in a thick band of connective tissue known as a perimysium.

What are the two types of muscle hypertrohphy?

Myofibrillar hypertrophy Sarcoplasmic hypertrophy

Myofibrillar hypertrophy

Myofibrillar hypertrophy refers to an actual increase in size of the muscle fibers (myo means "muscle" and a fibril is a threadlike cellular structure)

Rep scheme effect on different muscle fibers

A simple, but not incorrect, way to look at it is training in the 4 - 6 rep range mainly hits Type IIx fibers, 10 - 12 reps hits Type IIa, and 30 - 40+ reps hits Type I fibers. Simple enough.

What kind of weightlifting increases what kind of hypertrophy?

Heavier weightlifting preferentially increases power and induces myofibrillar hypertrophy, and lighter weightlifting preferentially increases endurance and induces sarcoplasmic hypertrophy. Researchers call this the "strength-endurance continuum."

Cellular fatigue

Cellular fatigue refers to pushing muscle fibers to their metabolic limits through the repetition of actions to muscular failure.

What are the three primary ways to stimulate muscle growth?

Progressive tension overload Muscle damage Cellular fatigue

Progressive tension overload

Progressive tension overload is, in my opinion (and the opinion of quite a few experts much smarter than me), the most important of the three. It refers to progressively increasing tension levels in the muscle fibers over time. That is, lifting progressively heavier and heavier weights.

What are the three types of muscle fibers?

Type I Type IIa Type IIx

Type I

Type I muscle fibers, also known as "slow-twitch" muscle fibers, and they have the lowest potential for growth and force output. They are, however, very dense with capillaries and rich in mitochondria and myoglobin, which makes them very resistant to fatigue.

Type IIa Type IIx

Type II fibers, also known as "fast-twitch" muscle fibers, both a and x, have a much higher potential for growth and force output than Type I fibers, but they fatigue very quickly. These are the types of fibers we are primarily concerned with in bodybuilding.

Sarcoplasmic hypertrophy

sarcoplasmic hypertrophy to an increase in the volume of the fluid, non-contractile components of the muscle (glycogen, water, minerals, etc.). Sarco means "flesh" and plasmic refers to plasma, which is a gel-like material in a cell containing various important particles for life.