You’re probably aware of two statistical patterns:

• Muscle size, strength, and power typically peak in early adulthood and then decline from there. But they don’t decline at the same rate. Muscle strength declines two to five times faster than muscle mass, and power declines even faster than strength.
• About a third of American adults meet the recommended standards for strength exercise (at least two sessions a week). As you’d expect, participation is highest in early adulthood (when muscles are most receptive) and then declines in middle age and beyond (when muscles need it most). Just 22% of men and 17% of women aged 65 years or older do resistance training two or more times a week.

The first trend suggests you should talk to every patient about resistance training.

The second suggests that a patient who does any sort of strength exercise is ahead of the majority who avoid it.

That’s important to keep in mind because the details we’re about to discuss won’t matter if the individual has no interest in lifting anything heavier than a grocery bag. Teasing out the importance of muscle form and function would be like explaining soccer’s offside rule to someone who couldn’t describe the shape of the ball.

And yet, muscle matters more than ever as we age. The patients you advise most likely have preconceived notions about muscle — bigger is best because that’s what draws the eye. Meanwhile, the good stuff, the information they really need for ongoing health, vitality, everyday function, frailty or fall prevention, and a higher quality of life, has little to do with looking great naked into your eighties (though who would turn that down?).

It comes down to the relevance of muscle size, strength, and power. They are simultaneously independent and intertwined, and the one that’s discussed least — muscle power — may be the most important.

It All Starts With a Routine

When someone begins a workout routine, they’ll see improvements in just about every aspect of muscular fitness: strength, size, power, endurance, balance, range of motion, and overall conditioning. (They’ll also put themselves on the path to a longer, healthier life.)

Those are all separate adaptations, but they have one common trigger:

“Physiological stress,” said Andy Galpin, PhD, professor of human performance at Parker University in Dallas, who also coaches elite athletes in a variety of sports. Force the muscles to do something new and challenging, and they’ll respond in a way that makes it easier to do the next time you impose the same challenge.

But while the adaptations are all occurring more or less simultaneously, “you’ll see a disproportionate increase in strength,” said Brad Schoenfeld, PhD, strength researcher and professor of exercise science at Lehman College in Bronx, New York.

Those initial strength gains, Schoenfeld emphasized, are primarily neural effects associated with learning new movements. The gains will be specific to the exercises in the routine. They won’t necessarily apply to real-world feats of strength like opening pickle jars or carrying a sleeping child upstairs.

An entry-level lifter who trains consistently can continue to build size, strength, and power more or less in tandem for months, if not years.

But the signals driving those adaptations are different from each other. At some point, because of personal preference or a perceived need, lifters often choose to focus on one specific adaptation over the others.

Muscle Size

If you don’t understand the importance of skeletal muscle mass, check in with any 16-year-old boy who’s too embarrassed to take his shirt off at the local pool.

Fortunately for him, and for anyone else who wants bigger muscles, hypertrophy training is “idiotproof,” according to Galpin.

Most beginning routines are based on bodybuilding models: two or three workouts a week, with exercises selected to build individual muscles with multiple sets and 8-12 repetitions per set.

They’re popular because they’re easy to understand, follow, and modify as needed. And any number of modifications can produce results. “There’s not a lot of specificity at the cellular and molecular level,” Galpin said.

You just need to find the right combination of frequency, volume, and intensity for your goals and preferences. The weights can be relatively heavy (five to eight reps per set), relatively light (15-25 reps per set), or anywhere in between.

The amount of muscle you build isn’t especially important for health or longevity. But using the muscle you have is crucial for metabolic regulation and functional independence.

As mentioned, however, muscle size often becomes the only thing people care about: the visual results. If that keeps them training over time, great, but it leaves a lot of physiologic money on the table.

Muscle Strength

Muscle strength is the ability to exert force. The more strength you have, the easier it will be to do everyday tasks that involve lifting and carrying.

More important: A patient’s current strength is a powerful predictor of their future health. Both upper- and lower-body strength are associated with a lower risk for early death from any cause.

As we noted, just about any type of workout will increase strength in the early stages. But if you decide to focus on strength, there’s a straightforward way to do it.

“The heavier you go, the greater your strength gains,” Schoenfeld explained. “There’s specificity to those gains.”

You’ll typically find some correlation between muscle size and muscle strength, and training with heavier weights will typically lead to increases in size and strength.

“But it’s not a physiological requirement,” Galpin said. “Your strength won’t ever limit your ability to grow muscle,” while athletes who compete in weight-class sports can and do get stronger without getting bigger. Nonathletes can, as well — a useful point for patients who worry that strength training will make them gain weight.

Muscle Power

The equation for power is force × velocity, which means the steep decline in muscle power late in life doesn’t occur in isolation.

“Strength is a foundational aspect of power,” Schoenfeld said. “If you’re losing strength, you’re necessarily going to lose power.”

Both of those developments are linked to the loss of muscle tissue. Specifically, the loss of type II muscle fibers, the ones responsible for generating both force and velocity.

“It’s kind of the ‘use it or lose it’ principle,” he explained. “As people get older and develop sarcopenia if they’re not training, they’ll maintain, for the most part, their type I fibers, which are the endurance-related fibers. But the strength- and power-related type II fibers die off.”

The loss of type II fibers also means the loss or denervation of the motor neurons responsible for activating them.

The consequence of that loss of neuromuscular function is a higher risk for falls, which is often catastrophic. “The entire game tends to be foot speed and recovery,” Galpin said. “If you trip, how quickly can you get your foot back in front of you?”

Power is the real X factor here. And that brings us to the most important question: How can you or your patients train to preserve or rebuild power and thus make their later years safer, healthier, and lasting far into the future?

Restoring Power

Training for power can be incredibly complex or surprisingly simple.

At the most athletic end of the spectrum are exercises based on Olympic weight lifting, such as cleans and snatches. You’ll rarely see them outside CrossFit boxes or facilities used exclusively by competitive athletes.

At the other end are exercises you often see in health clubs, such as kettlebell swings or medicine ball slams. Somewhere in between are burpees and box jumps.

The key to all power-focused training, whether complex or simple, is an explosive concentric portion of the movement — moving the load with maximum intent — preceded and followed by a slow, controlled eccentric portion when you return the weight to the starting position.

You’ll almost never see anyone in a commercial gym use that technique. But it’s not only easy to learn, it offers a wide range of benefits. That’s according to a 2022 review and meta-analysis by Schoenfeld and an international team of researchers.

The authors looked at studies in which older adults trained for power an average of two times a week for at least 6 weeks. Most of the studies used weight machines, with participants in the intervention group moving the load as fast as possible and those in the control group doing the same exercises at a slower speed.

Participants who trained for power increased power more than those in control groups, as you’d expect.

In most of the studies included in the review, they also showed superior improvements in functional challenges such as the 30-second chair stand (getting up and down from a chair as many times as possible) and the 8-foot up and go (rising from a chair, walking around a marker placed 8 feet away, returning to the chair, and sitting back down).

Both challenges require fast, coordinated action from the largest lower-body muscles, along with balance and agility.

That’s a pretty good argument for encouraging your older patients to add some power-focused exercises to their workout routines — or to begin a routine if they don’t already have one.

“I think it becomes increasingly important for older individuals who have not strength-trained,” Schoenfeld said. “And it doesn’t have to be either-or — all power or all strength.” A portion of the workout focused on power should be enough.

For everyone else, power-type training is more a matter of preference than of life-or-death necessity.

“In my opinion, if you’re younger, it’s probably not going to make much difference because you’ll maintain the majority of your type II fibers,” Schoenfeld said, which means you should have enough power to avoid falls. (Although, he added, there’s nothing wrong with “getting their aggressions out” by slamming a medicine ball against a wall.)

Most of the benefits of resistance exercise will come from simply doing resistance exercise. Any type, at any speed.

As Galpin put it, “Going from zero to one is saving more lives than going from one to two.”

Schoenfeld and Galpin reported no conflicts. Disclosure information for the study authors is available in the original study publications.