A personal trainer at a longevity clinic says you should care about 3 fitness markers if you want to live a long, youthful life

• Three essential fitness metrics can help you maximize your workouts for longevity.
• Your VO2 max can help assess heart health, while muscle mass and balance are key to staying active.

Exercise is one of the closest things we have to a miracle drug when it comes to living a longer, healthier life — and three essential fitness metrics can help you get the most bang for your buck.

Understanding key fitness measurements, from heart health to body composition, can help you streamline your workouts to stay youthful, said Caitlin Donato, a certified personal trainer and the director of fitness at the Pritikin Longevity Center in Miami.

"If you're going to take 30 minutes out of your day, then make the most of it," she told Business Insider. "Your time is valuable."

Pritikin offers a team of exercise physiologists who work alongside registered dietitians and doctors to create personalized plans for optimizing health.

Part of Donato's job involves guiding clients through an analysis of their fitness level and overall health, which includes a functional movement assessment and an exercise tolerance test.

She said that paying attention to your cardio fitness, muscle health, and stability can help you tailor your workouts to your lifestyle and achieve better performance and long-term health.

"It's not necessarily one size fits all," Donato said. "And if you have the ability to understand what you should be prioritizing over the person to your left or your right, that's where you can maximize your efforts, and that's where you see the most gains specific to what you need."

VO2 max is a key indicator of longevity

A healthy heart is one of the first lines of defense against chronic disease and other risks associated with aging. While a range of metrics can help you keep tabs on your heart, including blood pressure and cholesterol, one exercise-related test can help you see how well your heart is functioning overall.

VO2 max is a measure of how much oxygen your body can use during exercise. Research suggests that the higher your VO2 max, the better your endurance and odds of living longer. An increase in VO2 max can indicate you're getting fitter over time.

"It's effectively a marker of how efficient your body is, how you're metabolizing oxygen. And so we're able to see how that improves with these lifestyle changes, which is really, really neat," Donato said. "VO2 max is one of our best indicators of life expectancy."

Sports-medicine experts suggest mixing steady cardio work at a conversational pace and interval workouts with short bursts of high-intensity exercise to improve VO2 max.

Muscle mass is crucial for healthy aging

Your heart isn't the only muscle that can boost longevity. Building and maintaining muscle helps prevent frailty and promote better health as we age, Donato said.

A growing body of research suggests that lifting weights is just as important for longevity as cardio, and a mix of both is ideal.

Donato said that while muscle mass can start deteriorating in our 30s and 40s, "that's not a foregone conclusion." She added that resistance training could help.

You don't have to lift as heavy as possible or spend long hours in the gym to see results. Focus on good form, and gradually increase your effort to keep making progress.

"A strength routine is not necessarily about improving your one-rep max on a bench press, unless you want it to be," Donato said.

Good balance is linked to a longer, healthier life

Most people know to work on their cardio and strength in the gym but might be missing an underrated fitness measure for longevity: balance.

"When we talk about longevity, we look at balance," Donato said. "It's one of the things we want to make sure that we train for as we age, as our risk of falling and having injury sustained from falling increases."

Studies suggest that while slips and falls are a serious risk as we get older and become less stable, balance training can help.

One low-tech way to assess your balance at home is to stand on one leg for 10 seconds — a basic test that one study linked to a longer life.

To improve your balance and stability, practice simple exercises like a quick step to a knee raise. Core exercises like a Pallof press, plank, or farmer carry can also improve stability by strengthening the abs, hips, and glutes.

Donato said that incorporating exercises that mimic everyday movements — such as getting up from a chair, lifting a child, or carrying groceries — is essential to staying active and independent.

"It's geared toward improving the body mechanics and the movement patterns of the things we do every day, the things we care about doing," she said.