How Does Muscle Hypertrophy Happen?

Muscle hypertrophy is a term for the growth and increase of the size of muscle cells. The most common type of muscular hypertrophy occurs as a result of physical exercise such as weightlifting, and the term is often associated with weight training.

Hypertrophy Process

When you start exercising a muscle there is first an increase in the nerve impulses that cause muscle contraction.

This alone often results in strength gains without any noticeable change in muscle size. As you continue to exercise, there is a complex interaction of nervous system responses that result in an increase in protein synthesis over months and the muscle cells begin to grow larger and stronger.

There are two essential components necessary for the growth of muscles—stimulation and repair. Stimulation occurs during the contraction of the muscle, or during the actual exercising of the muscle. Each time that a muscle is exercised, contraction occurs. This repeated contraction during a workout causes damage to the internal muscle fibers. These muscles fibers are broken down throughout the course of a workout. Once damaged, these fibers are then ready to be repaired. This is where the muscle growth occurs.

Muscle fiber repair occurs after the workout while the muscles are in resting mode. New muscle fibers are produced to help replace and repair the damaged ones.

More fibers are produced to make up for the damaged ones, and this is where the actual muscle growth takes place.

Genetic Impact on Hypertrophy

Although the process of hypertrophy is the same for everyone, your results are likely to be different from others doing the same workouts. This variance in results is due directly to the genetic make-up of the muscles of the individual.

For some people, the process of hypertrophy occurs to a much larger degree or at a faster rate than it does for others. If you won the genetic lottery, you may grow bigger muscles or see results sooner than others at your gym. Unfortunately, the opposite may also be true.

The shape and appearance of a muscle are other factors that vary based on genetics. As badly as you may want a nice, round, plump bicep, it may not always be in the cards. The shape of a muscle is determined by the length of the tendons of the muscle. Tendon length is a genetic factor. For bigger muscles, it is better to have shorter muscle tendons. Someone with extremely long muscle tendons may see less growth and shaping of their muscles than someone with much shorter muscle tendons, despite doing the same amount (or more) weight lifting.

Exercises for Muscle Hypertrophy

The exercises that lead to muscle growth are those that contract the muscle against resistance repeatedly. You can choose a variety of weight training methods using free weights, exercise machines, resistance bands, or bodyweight exercises.

There are many suggested training regimens that vary the load weight, the number of repetitions, and the rest intervals between sets.

While each has their proponents, the end results may depend more on your dedication to your workouts and your body type.

Sources:

Morton RW, Oikawa SY, Wavell CG, et al. Neither Load nor Systemic Hormones Determine Resistance Training-Mediated Hypertrophy or Strength Gains in Resistance-Trained Young Men. Journal of Applied Physiology. 2016;121(1):129-138. doi:10.1152/japplphysiol.00154.2016.

Schoenfeld BJ. The Mechanisms of Muscle Hypertrophy and Their Application to Resistance Training. Journal of Strength and Conditioning Research. 2010;24(10):2857-2872. doi:10.1519/jsc.0b013e3181e840f3. 

West DW, Burd NA, Staples AW, Phillips SM. Human Exercise-Mediated Skeletal Muscle Hypertrophy Is an Intrinsic Process. The International Journal of Biochemistry & Cell Biology. 2010;42(9):1371-1375. doi:10.1016/j.biocel.2010.05.012.