How just minutes of running can supercharge your health

Yet about 31% of adults still don't get enough physical activity, including running. The most common reason people give is simple -- they don't have enough time.

That's where interval running comes in. It promises nearly all the same benefits of regular running, but in a fraction of the time.

What Is Interval Running?

Interval running is based on the principles of high-intensity interval training (HIIT), a workout style that alternates short bursts of intense effort with brief recovery periods. Although HIIT has existed for nearly a century, it became widely popular in the 1990s and 2000s through training methods like Tabata (20 seconds of intense movement followed by ten seconds of rest) and CrossFit (a demanding combination of cardio, gymnastics, and weightlifting).

In a typical HIIT workout, you might do 30 seconds of burpees at full effort, rest for 30 seconds, and repeat the sequence several times. The alternating pattern challenges the body to adapt and recover quickly, leading to major fitness improvements in less time.

This same approach can easily be applied to running for those who want to see results faster without spending hours on the road.

How to Apply HIIT Principles to Running

One simple example is the "10-20-30 method." This routine involves 30 seconds of walking or slow jogging, 20 seconds of running at a moderate pace, and a final 10 seconds of all-out sprinting.

Another option is the "fartlek" method (Swedish for "speed play"), which adds short sprints at random intervals during a jog. Instead of maintaining a steady pace, you mix in bursts of speed throughout your run, keeping things dynamic and fun.

The Science-Backed Benefits of Interval Running

Research consistently shows that HIIT-style running provides significant health improvements for the heart, metabolism, and body composition (how much fat the body stores and where it's located).

In studies involving overweight or obese participants, sprint intervals led to greater gains in cardiovascular fitness than steady-paced runs. Those who sprinted showed higher improvements in their V̇O₂ max -- the measure of how much oxygen the body can use during intense activity.

Even people who already run regularly can benefit. In one 12-week study, runners who added HIIT sessions to their endurance training saw greater improvements in V̇O₂ peak, another key measure of cardiovascular performance. Higher V̇O₂ values are linked not only to better athletic ability but also to a lower risk of premature death.

Improved Metabolism and Fat-Burning Power

Studies also show that alternating bursts of running and walking can improve metabolic health more effectively than continuous exercise. Specifically, interval training enhances blood glucose control, which helps reduce the risk of developing type 2 diabetes.

Workouts like the 10-20-30 method also stimulate the mitochondria, the energy-producing parts of cells, more than steady exercise does. This leads to improved stamina, better blood pressure, and healthier cholesterol levels. It even helps lower "bad" cholesterol while reducing overall cardiovascular risk.

Both continuous and interval running can decrease visceral fat (the harmful fat stored around organs), but HIIT accomplishes it in less time. Just 18 minutes of sprint intervals, three times a week, can lead to noticeable health benefits.

Getting Started With Interval Running

If you're ready to try interval running, start small. When running outdoors, you can sprint between two lamp posts, then recover by walking or jogging to the next one. This simple approach is a classic form of fartlek training.

At the gym, you can replicate this using either a motorized or non-motorized treadmill. Many treadmills even have built-in interval programs that guide you through sprint and recovery periods. Walking intervals can also provide benefits for beginners or those easing back into exercise.

Sprints can last anywhere from a few seconds to two minutes. To maximize results, aim to push your heart rate to around 90% of your maximum effort during the intense intervals, then allow yourself enough time to recover before the next one.

Build Up Gradually and Stay Safe

Like any fitness plan, interval running should be introduced gradually. If you've been inactive for a long period, jumping straight into intense workouts can increase the risk of injury or strain.

It's also wise to check with your doctor before beginning a new exercise routine, especially if you have health conditions. For example, people with diabetes should know that HIIT can cause temporary increases in blood sugar, so consulting a healthcare professional is important before starting.

A practical starting point is to include a few sprints in your next run -- anywhere from several seconds to a full minute. Over two to three months, you're likely to see measurable improvements in stamina and health.

If sprints feel too challenging at first, try the 10-20-30 method or "Jeffing" (alternating periods of running and walking). Even a small increase in running intensity now and then can lead to significant long-term fitness gains.

Small Effort, Big Results

Interval running proves that fitness doesn't have to demand hours of dedication. By combining short bursts of effort with brief recovery periods, you can boost cardiovascular health, strengthen metabolism, and burn fat more efficiently -- all in a fraction of the time.