Skip to content
Join Life Time
The legs of individuals who are sprinting on treadmills.

What if we told you that in one class, you could reap the benefits of a full week of exercise? If it seems too good to be true, well, it is — and it isn’t.

Moving your body daily is always best for optimal health. When it comes to getting the biggest bang-for-your-buck, though, there’s one type of cardio that consistently delivers more results in less time: sprint interval training (SIT). But there’s a catch.

SIT is the lesser-known cousin of high-intensity interval training (HIIT). Both SIT and HIIT are characterized by short, fast bursts of intense activity interspersed with periods of rest. Those alternating periods of activity and rest are repeated several times, hence the name interval training.

While HIIT and SIT have a lot in common, there’s one important difference: As the name implies, HIIT is high intensity but it’s not an all-out effort; a participant pushes themselves to 80 to 85 percent of their maximum heart rate (MHR). In SIT, an individual’s effort approaches 100 percent.

There lies the catch. SIT is an extremely effective and efficient form of exercise, which is why Ultra Fit, one of Life Time’s signature group training formats, is designed around it. But SIT requires full effort to reap the rewards — and sprinting at maximal intensity like there’s a tiger hot on your tail is not for everyone.

“Ultra Fit is advanced — it’s no joke,” says Abrea Wooten, national education manager at Life Time. “We created Ultra Fit to serve our high-intensity fitness fanatics and those looking for a competitive edge. But it’s also attracting people who don’t have time to spend hours working out, as well as members who want to really transform their health.”

For those up to the challenge, sprinting confers enormous benefits. According to a 2019 meta-analysis of 75 PubMed studies conducted by, SIT participants experienced a 39 percent higher reduction in body fat than HIIT participants even though they spent 61 percent less time exercising.

When compared to moderate-intensity continuous training (MICT), the differences that emerged in the meta-analysis are even more striking. SIT resulted in a 90 percent higher reduction in body-fat percentage compared to MICT even though participants spent 70 percent less time working out.

Transformation at a Cellular Level

Put another way, when the intensity level is “all out,” just three minutes of SIT a week can be as effective as 150 minutes of moderate-intensity cardio. The benefits of those three minutes range from ones you might expect, such as better cardiovascular health, to ones you’ve likely never heard of, like improved mitochondrial biogenesis.

If you just had a flashback to biology class, you’re probably wondering what mitochondria have to do with anything. Mitochondria are the microscopic power centers in your cells. They convert food and body fat into energy, among numerous other functions. Mitochondrial biogenesis is the growth and division of pre-existing mitochondria.

Whether your goal is better health or improved athletic performance, the bottom line is that you want lots of mitochondria and you want them to function well. Because of the intensity of the exercise, SIT can supercharge mitochondria production by creating more demand for energy inside your cells; this prompts a response to build more mitochondria.

“The research shows that sprinting changes us on a cellular level,” explains Wooten. “Sprinting is nature’s way of telling your body to toughen up and to rise to the occasion.”

In other words, sprinting is advantageous because we’re wired for it. SIT shocks your cells into better health and the net-net can include everything from a higher VO2 max (a key indicator of cardiovascular fitness) to better insulin sensitivity (an important marker for diabetes) and improved hormonal response.

“Sprint interval training is the closest thing we have to a fountain of youth,” says Wooten, noting that SIT increases both human growth hormone (HGH) and testosterone.

HGH’s primary role in the human body is cell regeneration, but it can also increase caloric burn and switch your body’s fuel source from carbohydrates to fat. Testosterone aids metabolic health, contributes to muscle gain, and supports cognition, among other benefits. HGH and testosterone levels decline as we age; exercise is one way we can support them.

Are SIT and Ultra Fit right for you?

Despite the many benefits, Wooten cautions that SIT, and Ultra Fit specifically, aren’t going to be the right “fit” for everybody. Whether or not you’ll enjoy the class will depend on your current fitness level and goals.

“You don’t have to be a runner to take Ultra Fit, because we’re only sprinting for 30 seconds at a time. And our trainers are going to teach you how to sprint both safely and effectively,” says Wooten. “On the other hand, if your main goal is weight loss, you’re really better off in GTX.” (GTX is one of Life Time’s other signature group training programs, which is suitable for all fitness levels.)

Ultra Fit is a good match for people who are training for athletic events; people who exercise regularly but whose results have plateaued; people who are short on time; and people who thrive on friendly competition, says Wooten.

Even then, Wooten doesn’t recommend taking Ultra Fit more than once or twice a week. Rather, think of Ultra Fit as a side dish in your training regimen, not an entrée. “It’s counterproductive to come more often because if you don’t give your muscles adequate time to recover, you won’t be able to sustain an all-out effort,” Wooten says. “You’ll only get to 85 percent of your MHR in your sprints, rather than 100 percent.”

Wooten also emphasizes that just because you can reap the benefits of a week’s worth of exercise in one class, it doesn’t mean you should. “Human beings aren’t designed to sit all day,” says Wooten. “From physical health to mood to social connectivity, exercise is important on so many levels, which is why we always encourage people to move their bodies daily.”

Julie Dulude

Julie Dulude is a Twin Cities-based writer.

Thoughts to share?

More From Life Time

Three people doing a kettlebell squat in a fitness class.

Signature Group Training

Individualized attention. Progressive programming. A supportive community. GTX, Alpha and Ultra Fit are structured workouts led by nationally-certified personal trainers.

View Signature Group Training Options for Members


More Like This

Mechelle Lewis Freeman sprinting on a treadmill in an Ultra Fit class alongside other individuals.

The Beginner’s Guide to Sprint Interval Training

By Mechelle Lewis Freeman

An eight-week sprint interval training (SIT) program that newbies can use to reap the benefits of this intense exercise method — or to prepare for taking your first Ultra Fit class.

Mechelle freeman life time talks smiling photo

Sprints, Strength, and Balance: A Look at Ultra Fit Training

With Mechelle Lewis Freeman, Olympian and Ultra Fit Coach
Season 6, Episode 13

The blend of sprinting with strength and balance work makes Ultra Fit training unique in its ability to improve your functional fitness and push you to your athletic limits. It’s also why Bahram Akradi, the founder and CEO of Life Time and developer of this format, describes Ultra Fit as one of the “most efficient, effective workouts.” In this episode, track and field Olympian and Ultra Fit Coach Mechelle Lewis Freeman digs into the science behind the training and explains how it’s designed to challenge your body and brain through every stage of life.

Listen >
an ultra fit class

The Ultra Fit Challenge

By Experience Life Staff

This cutting-edge workout combines strength, cardio, and neurological training to challenge your body and brain through every stage of life.

Back To Top