Building Muscle With Exercise: How Muscle Builds, Routines, And Diet

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Medical News TodaySubscribeHow to build muscle with exercise

Medically reviewed by Danielle Hildreth, RN, CPT — Written by Jayne Leonard — Updated on August 1, 2025

How does muscle grow?
Building muscle through exercise
Rest and muscle growth
Nutrition
For older adults
Tips for beginners
FAQ
Summary

People can build muscle by using their muscles more, such as by lifting weights or working out. Eating enough calories and protein is also important.

Skeletal muscle is one of the three major muscle types. Having enough muscle is essential for strength, balance, and agility.

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.

The use of binary terms such as “male” and “female” or “men” and “women” in this article reflects the language of the sources we have used. Unless otherwise noted, it is unclear whether the research we reference included participants with expansive gender identities.

How does muscle grow in the body?

Muscle size increases when a person challenges the muscles to deal with resistance. This resistance could be in the form of lifting a weight, pushing a heavy object, or working against the forces of gravity.

Resistance strains the muscles and results in tiny injuries to the muscle fibers. The body then repairs the fibers by fusing them, increasing their mass and size. This process is known as muscle hypertrophy.

Certain hormones, including testosterone, human growth hormone, and insulin growth factor, also play a role in muscle hypertrophy. Their levels increase after resistance training and likely increase muscle mass.

Sex differences in muscle growth

It is unclear if there are significant sex differences in how the body grows or maintains muscle.

While some studies find that male adults gain more strength from resistance training, others find the opposite, or no significant differences between sexes.

A 2020 review and meta-analysis of past research found that male and female adults gained similar results when following the same resistance training program, particularly for lower body strength.

For upper body strength, female participants had a more significant improvement.

The authors of the study notes that there are a variety of factors that may influence sex differences in strength training, including:

differences in overall body composition
testosterone and cortisol levels
differences in the types of muscle fiber found in different parts of the body
the menstrual cycle, which may affect muscle growth and recovery during different phases

Regardless of sex, muscle grows at different rates in different people for many reasons, including genetics, age, and overall health.

Building muscle through exercise

Most people can build muscle through exercise. For exercise to be effective, it should be both consistent and challenging.

Strength training

According to the Physical Activity Guidelines for Americans, 2nd edition, adults should engage in muscle-strengthening exercises that involve all major muscle groups at least twice weekly.

Examples of strength training activities include:

lifting weights
using stationary weight machines
resistance band exercises
body weight exercises, such as pushups and squats
climbing stairs
hill walking or hiking
some forms of yoga

The United Kingdom’s National Health Service (NHS) recommends working muscles to the point that a person must rest before continuing. For example, people often rest between sets.

To continue growing more muscle over time, people need to ensure workouts remain challenging as they get stronger via progressive overload, which involves gradually making exercise more difficult.

Cardiovascular activity

While it does not directly build muscle, cardiovascular exercise, also known as “cardio,” is essential for overall health. It can benefit a person’s heart, respiratory system, and stamina.

Current guidelines recommend that adults participate in at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity physical activity each week.

Rest and muscle growth

Rest is integral to building muscle. It is during rest that the body repairs muscles, making them stronger. Insufficient rest, or overtraining, slows fitness progression and increases the risk of injury.

A common recommendation is that people should rest each muscle group for 48 to 72 hours before exercising it again. For example, many people alternate upper and lower body workouts on different days.

However, a small 2018 study found that, after 12 weeks, there was little difference in body composition between people who trained on consecutive days and those who trained on nonconsecutive days.

The study only included 30 male adults, though. More research involving a larger, more varied group of participants is necessary to confirm if this finding is correct.

»Learn more: When and how to spend a rest day

Nutrition and building muscle

Eating a balanced diet is key to building muscle. Calorie and protein intake are especially important.

A 2019 review of past research states that the minimum daily protein requirement is 0.8 grams per kilogram of body weight (g/kg).

However, this is only the minimum recommendation. Evidence suggests that most people in the United States eat 1.0 to 1.5 g/kg of protein per day, and one review suggested that 1.6 g/kg could be beneficial. People who want to build muscle may benefit from getting more.

Sources of protein include:

meat
fish
eggs
soy and tofu
beans and lentils
nuts
protein powders, such as whey or pea protein

»Learn more: 30 muscle-building foods to fuel your goals

Strength training and aging

As a person’s age increases, so does the risk of conditions that can affect mobility.

Resistance training can help prevent this by building muscle and improving balance, which may reduce the risk of falls or other injuries.

If possible, older adults should try to meet the exercise guidelines for adults. If they are unable to do this, they should remain as physically active as possible. This may involve:

adapting exercises to their ability level
doing shorter, more frequent workouts
exercising while sitting down

»Learn more: A guide to strength training for older adults

Tips for beginners

Before trying a new exercise routine, it is important to consider safety. If a person has underlying health conditions or a previous injury, they should speak with a doctor first.

Otherwise, a personal trainer or gym employee can provide safety guidance, including how to exercise with the proper form. This is essential for reducing the risk of injury and maximizing the benefits.

Other tips include:

beginning with lighter weights or easier exercises
performing the movement with correct form and slow, controlled movement
remembering to breathe throughout
increasing the difficulty as movements begin to feel easy or unchallenging

Expect some mild soreness and muscle fatigue afterward, particularly when starting out.

However, extreme soreness, persistent pain that does not go away, or sharp and sudden pain are not typical and can be a sign of injury.

»Learn more: What to know about muscle soreness after exercise

FAQ

The following are commonly asked questions about building muscle.

Do muscles grow on rest days?

Yes. In fact, it is during recovery after exercise that muscles grow.Strength training causes minor injuries to the muscles, but during recovery, the body repairs them, making muscles bigger.

Yes. In fact, it is during recovery after exercise that muscles grow.

Strength training causes minor injuries to the muscles, but during recovery, the body repairs them, making muscles bigger.

Is a 30-minute workout enough to build muscle?

Yes, people can build muscle in 30 minutes, as long as the movements are challenging enough.People who are short on time may benefit from compound movements, which exercise several muscle groups simultaneously. Examples include squats and push-ups.

Yes, people can build muscle in 30 minutes, as long as the movements are challenging enough.

People who are short on time may benefit from compound movements, which exercise several muscle groups simultaneously. Examples include squats and push-ups.

Should I exercise if I have an injury?

No. Continuing to exercise with an injury could make the injury worse or slow recovery.If a person suspects they have an injury, they should speak with a doctor to learn how best to treat it.

No. Continuing to exercise with an injury could make the injury worse or slow recovery.

If a person suspects they have an injury, they should speak with a doctor to learn how best to treat it.

Summary

Muscle grows during physical activity. When muscles have to work to resist something, such as gravity, this creates tiny injuries in the muscle fibers. The body then repairs these injuries, resulting in more muscle.

People who want to build more muscle can do so via regular and challenging resistance training. This may mean lifting weights, using gym equipment, or body weight exercises. Nutrition is also important, providing the nutrients to help the body grow more muscle.

Strength training can benefit all adults, regardless of age, sex, or ability. However, people who want more guidance or have underlying conditions may benefit from speaking with a doctor or physical therapist.

Sports Medicine / Fitness

How we reviewed this article:

SourcesMedical News Today has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Carbone JW, et al. (2019). Dietary protein and muscle mass: Translating science to application and health benefit.https://pmc.ncbi.nlm.nih.gov/articles/PMC6566799/
Executive summary: Physical Activity Guidelines for Americans, 2nd edition. (n.d.).https://odphp.health.gov/sites/default/files/2019-10/PAG_ExecutiveSummary.pdf
Gharahdagi N, et al. (2021). Links between testosterone, oestrogen, and the growth hormone/insulin-like growth factor axis and resistance exercise muscle adaptations.https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.621226/full
How to improve your strength and flexibility. (2022).https://www.nhs.uk/live-well/exercise/how-to-improve-strength-flexibility/
Roberts B, et al. (2020). Sex differences in resistance training: A systematic review and meta-analysis.https://journals.lww.com/nsca-jscr/fulltext/2020/05000/Sex_Differences_in_Resistance_Training__A.30.aspx
Yang Y, et al. (2018). Effects of consecutive versus non-consecutive days of resistance training on strength, body composition, and red blood cells.https://pmc.ncbi.nlm.nih.gov/articles/PMC6015912/

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Medically reviewed by Danielle Hildreth, RN, CPT — Written by Jayne Leonard — Updated on August 1, 2025

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