Have you ever wondered how our bodies grow muscle mass? Did you know that if you have a better understanding of how it happens you’ll have a better understanding of how to develop your strength training program to get the maximum benefit?
More often than not, we take our musculoskeletal system for granted. We expect that when we get out of bed in the morning, our legs will bear our weight and takes us to the kitchen for breakfast. Our arms and hands will make the meal and our jaws will grind the food before we swallow it.
The muscles in our bodies are incredibly important because they are the biggest engine in the body that burns calories and keeps us moving. As a bodybuilder or during strength training we’re excited about working specific muscles to a point where their size and strength grows. We’d like show those large sized muscles off at the pool or to our friends. And the muscles we aim our efforts at are skeletal muscles.
These are the muscles we can see and which move our body from one place to another. This type of muscle is also called striated muscle because when doctors look at it under a microscope they see alternating areas of light and dark.
Many scientists believe that the number of muscle cells in the body are fixed by the time we reach age 20. The number of cells is determined by the hormones released in the body (testosterone produces more cells) and by the amount of exercise a person gets. If you get more exercise, your body will produce more muscle cells.
So, as a bodybuilder begins to “grow” muscle, they don’t really grow more muscle cells, but rather each cell gets bigger and stronger. As the muscle grows, so does the blood supply to the region to feed the muscles more energy and oxygen. The blood is carried through small capillaries.
Most cells have a single nucleus, or center of the cell where the majority of the genetic material is found. The nucleus is supposed to protect the genetic material and control the activity of the cell. Striated muscle cells have more than one nuclei and the ability to develop mitochondria. These are the powerhouse of the cell where converts chemicals into energy used by the cell.
As you work muscles, they produce more mitochondria. The higher the number of repetitions, the higher the number of mitochondria to produce energy. This is the reason that trainers recommend you do low reps with high weights to build larger muscle but include higher reps with lower weights to increase the number of mitochondria to feed the cells and grow them bigger.
One muscle is a bundle of cells which doctors call fibers. These are long and cylindrical in shape. One of the muscle fibers contains many myofibrils that allow the muscle to contract.
Regular exercise with higher weights and less reps, will also increase the number of myofibrils in each of the muscle cells. The increase in mitochondria will account for between 20 and 30 percent of the growth of a muscle and the increase in myofibrils will account for a growth of the same amount.
As you work a muscle with strength training it will also increase the amount of glycogen stored and the amount of connective tissue in the muscle fibers. These factors will also account for a portion of the size of muscle growth.
Bodybuilders will use two different terms to refer to muscle growth. The first is “Swell” which refers to the increased volume of the muscle by a supply of sarcoplasm in the myofibrils. This is triggered by a high number of reps with moderate weight.
The second term is “Shred” which refers to muscle definition with little subcutaneous fat. Heavy weights with low reps will result in micro-tears in the muscle which, as the body repairs, results in myofibrils that are more dense, larger and stronger.
Mens Health: How Does My Body Build Muscle
University of New Mexico: How Do Muscles Grow
ScienceDaily: Growing Strong Muscles without Working out
ScienceDaily: Exercise Triggers Stem Cells in Muscle
Washington University: Muscle Types and Sex Differences