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The new science of muscle: The big impact strategies you need to do (and the fluff you can ignore)
What you really need to know about getting—and keeping—muscle size, strength, and power.


Reviewed by Stuart Phillips, PhD

You’ll find muscle-building “rules” all over the Internet.

“Chug protein immediately after your workout—don’t miss that anabolic window!”

“Lift the heaviest weights you can manage. If you’re not lifting-to-failure every set, you’re not going to grow.”

“If you want to get stronger, you have to be taking creatine, BCAAs, HMB, beta-alanine, and [insert whatever muscle-building supplement is trending].”

While well-meaning, the above advice comes mostly from the body-building and powerlifting worlds. And, to be fair, if your or your client’s work revolves around getting trophy-worthy swole or strong, some of it’s worth heeding.

But if your (or your client’s) goals involve improving health, feeling comfortable in your clothes, and staying strong and muscular enough to age well and tackle life with gusto…

… do body-building and powerlifting rules still matter?

The short answer: Not really.

To understand why, however, you’ll need the more thoughtful answer—which this article provides.

You’ll discover:

  • How much time to put in at the gym to build and maintain muscle mass, strength, and power over time
  • What to eat to support your strength-training routine
  • Two muscle-building lifestyle habits that no one is talking about
  • Which supplements help slow age-related muscle loss—along with a popular one that doesn’t
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The underappreciated benefits of muscle strength

If you’re old enough to remember the 1980s, you’ll recall that the pursuit of health and wellness looked like slipping into silky dolphin shorts, and popping Richard Simmons into the VCR to get your heart pumping.

But strength training? Back then, it was for people who wanted to look like Arnold Schwarzenegger—not your everyday health seeker.

A lot can change in a few decades.

We now know…

Resistance training does more than merely produce bigger and stronger muscles.

For one, muscle tissue is metabolically active.

Each pound of muscle burns about 6 Calories while at rest—and much more during movement.

It may go without saying, but a healthier metabolism can help you stave off fat gain and its associated health risks as you age.

(That said, body fat isn’t the best proxy for overall health. Find out why: Is body fat good or bad?)

Next, strength training improves heart, lung, and overall health almost as effectively as cardio, says Stuart Phillips, Ph.D., a professor in the Department of Kinesiology at McMaster University and one of the world’s top researchers on muscle, resistance training, and their impact on health.

Here are some receipts to back this up:

In a study of 12,591 people, resistance training was associated with a 40 to 70 percent drop in cardiovascular events like heart attack and stroke.1 In a Danish study of 50 people, resistance training outperformed cardio at reducing a dangerous type of fat surrounding the heart (called pericardial fat). 2

Increased muscle mass3 4 5 6

  • Improves insulin sensitivity, and safely uses or stores excess blood sugar
  • Slows cellular aging
  • Secretes protective substances (called myokines) that regulate inflammation
  • Protects the lining of the arteries
  • Improves aerobic capacity

All of the above health benefits add up to reduced risk of…

  • Type 2 diabetes 7
  • High blood pressure 8
  • Dying from cancer 9
  • Heart disease 10
  • Depression and anxiety 11
  • Osteoarthritis 12
  • All-cause mortality 13

Can’t cardio do all of that, too?

It helps. (All forms of movement do, really.)

But resistance training provides a couple of perks that cardio doesn’t, especially as you age.

By preserving strength and muscularity, resistance training improves stability and prevents falls, the leading cause of injury for people 65 and older.

Muscle mass also cushions your bones. So, if you do fall, you’ll be less likely to break something.

We’re not here to pit cardio against resistance training.

That would be like saying vegetables are more important than fruit. Cardio and strength training both benefit overall health and longevity in synergistic ways. Ideally, we all do both. 14

Resistance training just doesn’t get the credit it deserves.

Because of these underappreciated health benefits, Dr. Phillips and several colleagues recently penned a paper (more like a manifesto) arguing that physical activity guidelines should give resistance training greater emphasis. 15

The vicious cycle of age-related muscle loss—and what to do about it

As we age, it becomes harder to maintain muscle and strength.

Partly, that’s because we tend to move less. However, even if you worked out as much in your 60s and 70s as during your 30s, you’d likely still grow weaker and smaller.

“Older skeletal muscle is more anabolically resistant than younger skeletal muscle,” says Dr. Phillips.

That means, as you age, muscle protein synthesis (the building of new muscle) slows while muscle breakdown accelerates.

You lose more muscle than you build—so size, strength, and power diminish.

Though Dr. Phillips and other scientists are still unraveling the causes of age-related anabolic resistance, some known factors include:

▶ Lower levels of sex hormones, especially estrogen and testosterone. 16 17

▶ Chronic underlying inflammation that rises with age. This decreases protein synthesis and promotes muscle protein breakdown, leading to muscle loss.

▶ Increased levels of body fat, which, in excess, can exacerbate inflammation, especially if you gain it deep in the abdomen (also called visceral fat).

▶ Increased cellular aging. Over time, the energy production centers of our cells (called mitochondria) grow less efficient. Also, an increasing number of old cells go into senescence. These damaged cells hang around, releasing harmful chemicals.

The withering away of muscle tissue accelerates over time, thanks, in part, to a vicious cycle:

  • Inflammation and inactivity lead to muscle loss.
  • Thanks to that lost muscle, your metabolism slows. You might feel weaker and more tired, too.
  • In response, you move and exercise less while accumulating more fat.
  • More body fat and less muscle generate even more inflammation—and the cycle continues.

At first, in your 40s, these losses are slow and gradual—so much so that you likely won’t notice yourself losing muscle size, strength, and power.

In your 60s and beyond, muscle and strength loss intensifies, as this graphic from a recent study illustrates. 18

Graph shows how muscle mass generally decreases over time starting around the age of 40. Some events, like like acute illness or injury leading to extended bed rest, contribute to disproportionate dips in muscle mass. This mass is usually regained so long as training and nutrition is resumed.

(Fun fact: Three weeks of bedrest can age your muscles by 30 years.19 But don’t worry; following the advice in this article can help you reverse the clock again.)

Lose enough muscle, and you’ll struggle to do things that once came easily.

Tossing a suitcase into an overhead compartment. Opening jars. Climbing and descending stairs. Getting out of a chair or off the floor without assistance.

These losses, however, aren’t inevitable. Below, we’ll show you the most effective ways to stay strong over the decades.

How to build muscle strength, size, and power: Big, medium, and small impact strategies

Not all strategies to improve muscle size and function are created equal.

What makes things extra confusing is that sometimes the strategies that only have a tiny impact are promoted disproportionately—usually through anecdotes on social media, or by companies who serve to gain by selling these strategies to you.

Image shows how different factors affect muscle growth. Some factors, like genetics, we have no control over. Other factors, like resistance training, diet, sleep, and supplements, we have more control over.

The image above shows the proportion of influence that various factors have on muscle size, strength, and power.

As you can see, the factor that has the largest influence is your genetics. It’s also a factor you have zero control over.

However, there are several factors that you do have more control over.

And if fully leveraged, these factors can make an enormous difference. (Again, some more than others, so prioritize where you spend your energy and resources.)

Below, we’ll focus on the specific strategies that can influence these controllable factors.

Big impact strategy #1: Lift heavy stuff.

Muscles respond to the demands we put on them.

Ask your muscles to lift heavy loads, and they’ll grow bigger, stronger, and more powerful.

Assuming you’re not trying to emulate the body type of a Marvel superhero, you can make progress with less effort than you might expect, especially if you’re currently sedentary.

How heavy do you need to lift?

▶ Frequency: One weekly strength training session will help most people progress, and could be all you need in a pinch.

Two to three sessions a week is optimal for most in terms of staying healthy and slowing aging—and will put you in the top 15 percent of all people, says Dr. Phillips.

Four weekly sessions? Now you’ve joined the group of people who exercise because they want to get better at exercising, and keep beating their own deadlifting PRs.

▶ Effort: On a scale of 1 to 10, you’ll want your final few reps to feel like a 7 to a 9 in perceived effort.

(And in case you’re curious: Free weights and machines work equally well at helping you to build and maintain muscle.20)

▶ Time: Your training volume will depend on your personal goals, preferences, and time constraints. But here are two general guidelines:

  1. Try to include a mix of lower repetition (3 to 6 reps), higher load work along with higher repetition (8 to 20 reps), lower load work. This blend maximizes strength and muscle building while minimizing injuries.
  2. Aim for 2 to 3 sets of 4 to 6 exercises per session. That will likely translate to about 30 to 60 minutes of gym time per session.

As we mentioned, those are merely guidelines—not rules.

If you love lifting, luxuriate in your time at the gym, going longer or more often. Similarly, if you’re tight on time, any strength training is better than none. 21

When deciding what and how to lift, the most important question is:

What will you do consistently?

How much time and effort can you devote to resistance training?

What types of strength-building activities do you enjoy (or at least don’t despise)?

Build your program around that.

Big impact strategy #2: Consume enough protein.

Dietary protein stimulates muscle growth.

In order to prevent deficiency, a young, sedentary person should consume 1.2 grams of protein per kilogram of body weight (or around 0.55 g per pound of body weight).

But protein needs go up with activity level and age. And in this article, we’re not just talking about preventing deficiencies. We’re talking about optimizing.

How much protein do you need to eat?

If you’re over 30 and a regular exerciser, you likely need around 1.6 to 2.2 grams of protein per kilogram of body weight (or about 0.75 to 1 gram per pound). 22

Depending on your body size, that adds up to about four to eight palm-sized portions of protein-rich foods daily.

(For a detailed breakdown of your protein needs based on your body weight, activity level, dietary preferences, and goals, check out our Macros Calculator.)

Protein quality and the post-workout “protein window”

As with many nutrition topics, there’s lots of hand-wringing about stuff (like the two below) that we’d confidently classify as “minutiae.”

Here’s our take:

Eat protein around exercise—but don’t worry about some narrow anabolic “protein window.”

Just after a workout, your muscles are hungry for protein.

But as long as you’ve consumed protein within three hours of your workout, they’ve got what they need.

In other words, if you ate lunch an hour ago, you don’t have to worry about chugging a protein shake right after your workout. If you work out fasted, that shake is a good idea.

Protein is protein is protein—more or less.

The human body doesn’t absorb protein as efficiently from plants as from animal sources.

That’s why plant-based athletes and physique competitors may bump up their protein consumption by about 10 percent. For them, tiny margins can determine whether they earn the glory of the podium.

However, if you’re not about to step on a stage in your underwear, this small difference in protein absorption won’t make a noticeable difference.

Focus on simply consuming enough overall protein from a variety of foods, rather than worrying about whether your protein comes from animals or plants.

(Want to know more about the differences between plant and animal protein? Read: “What’s the best protein powder?”)

Big impact strategy #3: Eat enough calories.

Eat more calories than you need and you’ll gain more than just muscle. You’ll also gain fat.

Depending where on your body fat is stored, and how much, sometimes excess fat can increase inflammation and hinder muscle growth.

(Learn more about body fat here: What Everyone Needs to Know About Body Fat)


Consume too few calories, and you won’t be able to build new muscle. You might even lose some.

You need enough gas in the tank to recover and refuel, so you have the energy to face another strength session.

Plus, your muscle tissue needs energy to rebuild itself.

This is why extreme diets tend to backfire. Eat too little, and you’ll lose some fat, but you’ll lose muscle tissue, too—sometimes considerable amounts.

A 10 to 13 percent loss in overall weight can lead to an accompanying 5 or 6 percent loss in muscle mass. 23

By consuming enough calories—especially calories from protein—you’ll put yourself in a better position to preserve muscle as you attempt to lose fat.

How many calories is enough?

People vary widely in their energy requirements.

Body size, gender, muscularity, and activity level all impact how many calories you require to keep your body purring.

To find out how much energy (in the form of calories and macronutrients) your body needs, use our free Macros Calculator.

Big impact strategy #4: Eat minimally processed whole foods.

Veggies, brightly colored fruits, nuts, extra virgin olive oil, beans, tubers, and fatty fish provide a wealth of nutrients that help keep inflammation regulated—and slow muscle loss as you age.

People who followed a Mediterranean-style diet rich in anti-inflammatory whole foods were less likely to be diagnosed with age-related muscle loss (called sarcopenia), found a study of 2,963 adults in their 60s and 70s. 24

Conversely, folks who consumed diets loaded with highly processed pro-inflammatory foods were more likely to be diagnosed with the disease. 25 26 27

How much of your diet should be minimally processed?

Consuming anti-inflammatory foods doesn’t have to be complicated. You don’t need to worry about consuming the BEST superfood vegetable or grain.

Instead, try to follow two basic principles:

⬆️ EAT MORE minimally-processed whole foods like colorful fruits and veggies, whole grains, healthy fats (like olive oil, nuts, and fish), and beans and legumes.

⬇️ EAT LESS fewer highly processed foods like sweets, fried foods, and chips.

Ideally, your diet is made up of about 70 to 80 percent minimally processed foods.

If you’re currently eating mostly processed foods, just start by replacing one processed food item with a minimally processed food of your choice.

Do that consistently, and once that feels easy, make another swap. Every improvement counts.

Big impact strategy #5: Get enough rest and recovery.

More and more training isn’t always better for optimal muscle growth.

That’s because it’s actually during rest that your body adapts and grows stronger.

A resting body—with the help of protein—works on repairing the (normal) microscopic tears that are incurred in the muscle during a workout.

After this process is done—ta-da!—you’ll have slightly stronger muscles.

If you keep training back-to-back, this micro-damage doesn’t get a chance to heal, leaving you more vulnerable to injury, and paradoxically, weaker muscles.

How much rest and recovery do you need?

Most adults require 7 to 9 hours of quality sleep every night.

That means you’ll want to prioritize sleep and address any problems (like menopause-induced night sweats) that interfere with it.

(Read more: Five ways to manage menopause-related sleep issues.)

You’ll also want to have designated “rest days” between tough workouts. So, if you do a challenging leg day in the gym on a Monday, don’t do legs again on Tuesday. That said, a light cardio day or an upper body day would work.

To decide how much rest you need—between workouts and at night—listen to your body. If you’re feeling exhausted and exceptionally sore, you might need more downtime.

Medium impact strategies

The “big impact” strategies above should serve as your foundation. They represent roughly 70 to 80 percent of what you have control over, in terms of muscle building.

However, these “medium impact” strategies are still helpful; they can allow you to execute your “big impact” strategies more consistently—and also just live a fuller, more enjoyable life.

Maximize your social connections.

Social connections—or lack thereof—can have massive impacts your health.

Chronic isolation and loneliness drive up inflammation, 28 and can be as damaging to health as smoking 15 cigarettes per day. 29

Working out with a friend or in a group setting can nourish your social life, but can also help you keep up your exercise habit.

Research shows people train more consistently when they do it with a friend or a group of people. 30 31 And, they push themselves more, too. 32

(So many gains!)

Have fun.

Fun works for similar reasons as social connections: It helps you implement your big impact strategies more consistently.

Keep fun in mind when deciding how to strength train.

Bench press your kid, crank Nirvana while you do pushups at the park, get workout gear you feel fly in, watch Selling Sunset while you’re on the treadmill, and set small, satisfying challenges for yourself.

Whatever helps you inject a little pleasure or a sense of play into your workouts.

(Not an exercise lover? Read this: How to exercise—when you don’t like to exercise)

Small impact strategies

Small impact (or frankly, no impact) strategies are what you’re most likely to hear people debating about on the internet and at the gym.

However, this stuff is likely only responsible for between zero and ten percent of your progress (and ten is probably pushing it).

Below we’ve listed four of the better-researched muscle-building supplements.

Note that each supplement, in isolation, likely results in such a slight difference that you might not even notice it, says Dr. Phillips. When taken together though, they may offer synergistic benefits that could nudge you into ten percent territory.

(BTW: Despite all the buzz about branched-chain amino acids—or BCAAs—they’re not likely worth the hype. Find out why: What are BCAAs, and are they worth it?)

Creatine monohydrate

This cheap, nearly-tasteless powder has been used and researched for decades.

Creatine helps muscles to contract, speeds recovery, and increases muscle strength and power. However, it only modestly benefits muscle growth.

Bonus: Creatine may also improve short-term memory and mental clarity. 33 34

▶ Recommended dose: 3 to 5 grams a day

Omega 3 fatty acids

Possibly because of their anti-inflammatory effects, omega 3 fatty acid supplements seem to lead to small increases in strength. 35

Other research indicates that the supplement may help prevent and treat sarcopenia as people age. 36

▶ Recommended dose: 1 to 3 grams of combined EPA and DHA

Vitamin D

A deficiency in this sunshine vitamin can interfere with muscle growth. 37

However, taking vitamin D when your vitamin D levels are already sufficient won’t give you an edge.

▶ Recommended dose: 1000-2000 IUs daily—or dose recommended by your doctor—until normal serum levels are restored


When consumed before a workout, caffeine can help increase muscle strength and power during your session and lower your perceived exertion. 38

However, the recommended 3 to 6 milligrams per kilogram of caffeine can trigger anxiety in some. So, start low.

Experiment with 100 milligrams, roughly the amount in eight ounces of brewed coffee.

If you feel great and want more mojo, increase your dose as needed.

▶ Recommended dose: 3 to 6 milligrams per kilogram of body weight

From sedentary to strong

When Dr. Phillips teaches exercise science, he asks his students to imagine this scenario:

“You wake up tomorrow, smoke a pack of cigarettes, eat fast food every meal, and take fewer than 1,200 steps.”

The students cringe and shift in their seats. Some ask, “Why would I ever want to do that?!”

Dr. Phillips replies: “How you feel right now is how some of your clients will feel when you tell them they need to take 10,000 steps a day and do three hour-long strength training sessions each week.”

For most, that’s overwhelming. After all, between 70 and 80 percent of people are doing no strength training at all. 39 40

If you’re a coach, you have an opportunity, but also a challenge: Make muscle-building a priority, but also accessible.

If you start clients with just a 10-minute program they can do twice a week, you’ll move many of them from “sedentary” to “active.” From there, you can add more—if the client feels ready.

Your clients will feel like they’re winning—and their muscles will too.


Click here to view the information sources referenced in this article.