Here's how to get the most of your workout time according To Science

Modern living has a way of making us feel pressed for time and compelled to find the most effective ways to spend the precious hours we don't sleep. High-intensity interval training, or HIIT, is a popular workout routine that embodies this experience.

HIIT claims to provide the finest exercise in the shortest period of time. Interval training has been utilized by runners for over a century to build endurance by alternating between sprints and jogging. However, HIIT didn't become popular until approximately a decade ago, when exercise physiologists began to publish research after study indicating that intervals might provide the most health benefit for your workout time. The seven-minute workout, popularized by the New York Times, first arrived on the scene in 2013, followed by the one-minute workout in 2016.

In a recent study conducted by the American College of Sports Medicine, fitness experts named HIIT as one of the top fitness trends for 2020. Interval-based exercises are already appearing virtually everywhere: in fitness franchises like Shred415 and Orangetheory, in group programs at YMCAs, on apps and YouTube, and even in Oprah's O magazine. They frequently promise to burn fat and "metabolically charge the body" in a short amount of time, as Orangetheory puts it.

However, there are some key distinctions concerning HIIT that scientists have discovered that have gone lost in the excitement. These workouts' established advantages are related to a specific sort of interval training and have nothing to do with weight loss.

What exactly is HIIT?

Short bursts of intensive exercise are typically interspersed with intervals of rest or lower-intensity exercise in HIIT programs. These workouts are often found in fitness studios and on the internet, and they combine aerobic and resistance training with Workout Clothes.

To be clear, the majority of the interval exercises investigated by academics are primarily focused on aerobic activity. That is, the scientific knowledge of interval training is based on a more particular program than what is often seen in gyms, movies, and periodicals. And the researchers' definition is important because when discussing the evidence of benefits, we need to be explicit about the kind of exercises on which science is founded. When researchers talk about HIIT, they're referring to exercises that alternate hard-charging bursts in which a person's heart rate hits at least 80% of its maximum capacity for one to five minutes with times of rest or less intensive activity. (It's difficult to tell if you're functioning at 80 percent capacity, but a Fitbit or heart rate monitor can assist.)

"There's a clear definition of HIIT in terms of heart rate," Todd Astorino, a professor of kinesiology at California State University San Marcos, noted.

SIT studies also include all-out bursts of intensity (working at 100 percent of your heart's capability). I'll also draw on the SIT study, which is likewise focused on intervals and demonstrates comparable effects.

Is high-intensity interval training (HIIT) the most effective weight-loss exercise?

Interval training is undeniably a time-efficient technique to burn calories. Researchers have frequently demonstrated that people may burn equivalent quantities of calories in HIIT programs lasting 20 minutes vs longer continuous exercise routines lasting 50 minutes. The reason for this, according to Gibala, is that higher-intensity exercise, such as intervals, disrupts the body's homeostasis, "and it literally requires more energy and oxygen to return it to normal basal levels." (In a minute, we'll discuss the associated "afterburn" effect.)

However, whether that calorie burn translates into weight reduction is the question, and here is where HIIT falls short. A 2019 systematic analysis of studies comparing HIIT and SIT to moderate-intensity continuous training discovered that both regimens performed similarly in terms of fat reduction. (As an aside, the journal inflated the review's conclusions, prompting one of the study's authors to contextualize them in this Twitter conversation.)

"Many people exaggerate the potential for interval training to produce weight loss," Gibala added. However, this is a problem with exercise in general, not HIIT in particular. As previously said, it is far easier to lose weight by reducing calorie intake than than attempting to burn extra calories.

According to Jeffrey Horowitz, a kinesiology professor at the University of Michigan, this is especially true if your workout is only 20 minutes long. "You need to exercise [for] a longer amount of time to burn a lot of calories." HIIT routines, by definition, are brief. So, if you want to lose weight, you should consider a longer interval program, and you should absolutely look at your food."

"In terms of the total volume of calorie burning, it tends to be minor relative to what you can achieve with dietary adjustments," Gibala said.