Staying active is vital for overall health, and it is also the best way to build skeletal muscle. Skeletal muscle is one of the three major muscle types. Tendons attach these muscles, which contract and cause movement, to bones.

People are best able to improve their muscle mass by performing the right exercises and eating particular foods.

In this article, we look at how to develop the skeletal muscles, including what types of exercise to engage in, which foods to eat, and when to rest and stretch.

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Age, sex, 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 proteins
  • inhibiting the breakdown of protein
  • activating satellite cells, which are a type of stem cell that plays a role in muscle development
  • stimulating anabolic hormones, which promote muscle growth and protein synthesis
  • enhancing tissue growth

Strength and resistance training can help the body:

  • release growth hormone from the pituitary gland
  • stimulate testosterone release
  • improve the sensitivity of the muscles to testosterone

Do 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 sex, 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.

People build muscle at different rates depending on their age, sex, and genetics, but muscle development significantly increases if exercise is:

  • consistent
  • challenging
  • long-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 weights
  • using stationary weight machines
  • resistance band activities
  • body weight exercises, such as pushups and squats
  • strength 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 rate
  • for 30–45 minutes at a time
  • on 4–5 days per week

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.

Eating a balanced and healthful diet is key to staying fit. For people who wish to build muscle, protein intake is especially important.

Current guidelines recommend that adult males and females consume 56 grams (g) and 46 g, respectively, of protein every day.

The timing of protein intake may also be of importance. A paper belonging to the 2013 Nestlé Nutrition Institute Workshop Series suggests that consuming 20 g of dietary protein during or immediately after exercise helps stimulate muscle protein synthesis, reduce protein breakdown, and promote more effective muscle reconditioning.

Sources of protein include:

  • meat
  • fish
  • eggs
  • milk and cheese
  • soybeans and tofu
  • beans and lentils
  • nuts
  • seeds

A fitness professional can advise people on the correct form to use when lifting weights and using other gym equipment. Using the right technique reduces the risk of injury and enhances the potential to build muscle.

People may also benefit from following the advice below:

  • Warm up and stretch for 5–10 minutes before engaging in strength or cardio activities.
  • Begin with light weights and increase the weight or resistance level gradually.
  • Carry out all exercises using the correct form, breathing techniques, and controlled movement.
  • Expect some soreness and muscle fatigue afterward, particularly in the early stages. However, too much discomfort or exhaustion suggests that the workouts are too intense, too frequent, or too long.

People should consult a doctor before embarking on any new exercise regimen if they have underlying health conditions or concerns about injury. Otherwise, a personal trainer or gym employee can provide safety guidance.