The Most Baffling Fitness Terms, Explained

What does HIIT stand for? Plus, eight other common yet confusing fitness terms explained.

If you have no idea what the heck ‘HIIT’ is, or wouldn’t know what a ‘macro’ is if it smacked you in the face, you’re not alone. According to a study commissioned by My Vital Metrics, 68 percent of Americans have lied about understanding something fitness-related in order to avoid embarrassment. (And, fun fact, macro and HIIT are the two most-Googled fitness-related terms). So to help you save face, we asked celebrity trainer Jason Wimberly, founder of The Naked Trainers, to offer simple and straightforward definitions of nine of the most confusing fitness terms out there.


So, what does HIIT stand for? It’s an acronym for high intensity interval training: “Basically, you go as hard as you can for a certain period of time, also known as reaching max effort, then rest, then do it again,” explains Wimberly. (HIIT is associated with cardio-type workouts, think running, spinning, etc.) It’s hard—and effective. Research has shown that doing HIIT for a shorter amount of time is more effective than doing steady cardio for a longer period of time, adds Wimberly. The goal is to really get breathless—AKA move into an anaerobic state, more on that in a minute—during those intervals of work.


Often referred to as plyos, think of this as any kind of jumping movement: jumping lunges, box jumps, squat jumps, or any intense burst of energy that requires max force in a short amount of time, says Wimberly. Oh, and yes, this includes those beloved burpees, too. “Generally performed with bodyweight only, plyometrics are one of the best ways to increase your overall fitness levels, as they often toggle between anaerobic and HIIT as well,” he adds.


“For the 21 years I’ve been a trainer, I have always worked in supersets. It’s a fitness term used to describe two or more exercises done in rapid succession with little break,” says Wimberly. It helps you both max out certain muscle groups while targeting different parts of the muscle. Think doing two to three shoulder exercises in a row, but ones that work different parts of the shoulder. Supersets are a more effective way of working out than isolating single muscles one at a time, he adds.


Also known as static strength training, isometric exercises challenge the muscle by holding a specific position, rather than completing full-range extension. In other words, you hold one position so that the muscles are engaged without movement. Examples include planks, wall sits, hollow body holds, glute bridges, dead hangs, and dumbbell hold; however, you can really turn almost any movement into any isometric exercise by simply holding the position during muscle contraction.

Aerobic exercise

“Simply put, this is your cardio. Aerobic exercise refers to moderate physical activity that uses free oxygen like running, jogging, walking, spinning,” says Wimberly, during which you’re maintaining a steady heart rate, even if it is elevated. It’s great for maintaining the overall health of your lungs and respiratory system, though, to burn fat, you’ll want to focus on strength training and HIIT, he adds.

Anaerobic exercise

Anaerobic exercise involves getting fully breathless. Whereas with aerobic exercise you’re sustaining a set pace, going anaerobic means maxing out to force your body to break down glucose for energy without using oxygen, explains Wimberly. It boosts your body’s metabolism not only during the activity, but for the hours after, but you really have got to the point of gasping for air.


“This is just a fancy word of saying you have strong muscles from lifting weights,” says Wimberly. Weight training is essential for overall health, especially for the joints and bones. and improves nearly every function of the human body. Just remember to build in time for rest and recovery—muscle growth happens after the workout, not during, he says.

Anabolic State

Essentially, this is a good place to be, as it’s when the body is growing and changing in a good way. If you’re lifting weights, eating enough calories, sleeping a lot, and all the boxes are checked off, this is when you can be anabolic, he says. “For most athletes, the goal is to be as anabolic as possible.”

Keto vs. Ketosis

These two terms are often used interchangeably, and while they are related, they’re not the same thing. Keto refers to a low-carb, low-sugar, high-fat diet, says Wimberly. The goal of following a keto diet is to put the body into ketosis, a metabolic state where the body can use and burn fat for energy instead of carbs or sugar, he points out. (While it can yield great fat loss, he notes that, as a trainer, he’s not a fan of this type of extreme diet and cautions that it can have some pretty negative effects on the body.)