27/01/2021
How does muscle grow in the body?
Share on PinterestAge, s*x, and genetics can all affect the rate at which a person can grow muscle.
Muscle size increases when a person continually challenges the muscles to deal with higher levels of resistance or weight. This process is known as muscle hypertrophy.
Muscle hypertrophy occurs when the fibers of the muscles sustain damage or injury. The body repairs damaged fibers by fusing them, which increases the mass and size of the muscles.
Certain hormones, including testosterone, human growth hormone, and insulin growth factor, also play a role in muscle growth and repair.
These hormones work by:
improving how the body processes proteinsinhibiting the breakdown of proteinactivating satellite cells, which are a type of stem cell that plays a role in muscle developmentstimulating anabolic hormones, which promote muscle growth and protein synthesisenhancing tissue growth
Strength and resistance training can help the body:
release growth hormone from the pituitary glandstimulate testosterone releaseimprove the sensitivity of the muscles to testosteroneDo males and females grow muscle differently?
A variety of factors — including genetics and the levels of estrogen and testosterone in the body — can affect how rapidly a person can develop muscle.
Regardless of biological s*x, muscle grows at different rates for people with different body types.
Both males and females can have the following body shapes, and each requires a different approach to muscle building:
Mesomorphic: People with this body type tend to be muscular and generally build muscle mass far more quickly than people with other body types.Ectomorphic: This term describes a slim or straight frame. Ectomorphs have a lower chance of building muscle mass but can increase their strength through resistance training.Endomorphic: This body type is more rounded or curvy. People with an endomorphic body can build muscle most effectively through strength training.
However, in an interview with Australian news service ABC, sports scientist Dr. Tony Boutagy points out several traits that are more pronounced in males and support faster muscle growth. These include a larger muscle mass, higher testosterone, and tighter joints.
Building muscle through exercise
People build muscle at different rates depending on their age, s*x, and genetics, but muscle development significantly increases if exercise is:
consistentchallenginglong-term
People also achieve the best results when they follow exercise with enough rest.
The best type of exercise to build muscle is strength training, although cardiovascular activity can also provide benefits.
Strength training
It takes several weeks or months of consistent activity and exercise before muscle changes become visible.
According to the Physical Activity Guidelines for Americans 2015–2020, adults should engage in muscle-strengthening exercises that involve all major muscle groups at least twice weekly.
Examples of strength training activities include:
lifting free weightsusing stationary weight machinesresistance band activitiesbody weight exercises, such as pushups and squatsstrength training classes that incorporate some or all of the above activities
A 2019 review looked at the effects of resistance training on the conditioning of crew members preparing for spaceflight. Its findings suggest that resistance training with three weight sets was generally more effective than performing one set.
However, a one set resistance program also yielded benefits.
Strength training and aging
As a person’s age increases, so does the risk of limited mobility and other skeletal and muscular problems, such as osteoporosis or osteoarthritis.
However, older adults should try to meet adult exercise guidelines if they can. If they are unable to do this, they should remain as physically active as their physical limitations allow.
Strength training is also beneficial for older adults to prevent injury and aid recovery.
Cardiovascular activity
Also known as aerobic activity or simply “cardio,” cardiovascular exercise benefits a person’s heart and respiratory system.
Cardio is vital for overall health. Current guidelines recommend that adults participate in at least 150 minutes of moderate intensity or 75 minutes of vigorous intensity physical activity each week.
While some people believe that aerobic exercise does not help build muscle, recent research disagrees. Regular cardio can support muscle growth and function. It also increases overall fitness levels, which may help reduce the risk of injury.
For optimal muscle building, the authors of a 2014 review suggest that people carry out aerobic exercise:
at 70–80% of their heart rate reserve, which a person can calculate by subtracting their resting heart rate from their maximum heart ratefor 30–45 minutes at a timeon 4–5 days per week
Rest and muscle growth
Rest plays an integral part in building muscle. By not letting each of the muscle groups rest, a person will reduce their ability to repair. Insufficient rest also slows fitness progression and increases the risk of injury.
According to MOVE!, an exercise initiative from the U.S. Department of Veterans Affairs, people should not carry out strength training on the same muscle group on 2 consecutive days.
Getting enough sleep is also important for the process of muscle growth. The researchers behind a 2011 study hypothesize that sleep debt decreases protein synthesis, contributes to the loss of muscle mass, and inhibits muscle recovery. However, many further studies are necessary to confirm the link.
A 2019 study found no direct correlation between sleep and muscle gain. However, the study authors do suggest that sleep deprivation can increase the amount of cortisol that circulates the body after exercise. Cortisol is a stress hormone.
Reducing stress may help a person build muscle, as the hormones that the body releases during periods of stress have a negative effect on muscle development
