ClassPass 101: Everything You Need to Know About HIIT

Whether you’re looking to build muscle, sculpt and tone, or improve your endurance, HIIT workouts are a fast-paced way to get a lot out of your gym time. Find out what you should expect the first few times you go.

What to bring
You will be sweating, so bring along a towel and enough water to get you through the workout, and maybe a little extra for afterwards to rehydrate. A heart rate tracking monitor, if you regularly use one, can be a fun addition to class, as they provide a clear picture of how hard you’re working and how quickly your heart rate comes back to a normal tempo during recovery periods. The faster you recover, the better.

For outdoor HIIT classes, a yoga mat or gloves can be helpful, just in case you find yourself on pavement.

What to wear
Dress in workout gear you can move and sweat in. Nothing kills a tough interval like having to stop to hike up your pants or pull down your shirt. Supportive waistbands are key, as is fabric that wicks sweat away from the body to keep you cool.

When it comes to footwear, some HIIT classes are taught barefoot, but usually only if the floor is a padded. Typically, a structured sneaker or a flatter CrossFit shoe works well. Just remember that your knees may be taking some impact and you may need to move quickly. Whatever is comfortable and supportive for your feet is perfect.

What to expect
HIIT classes are generally 45-60 minutes, depending on the studio you visit. Classes can range from as few as two people to as many as 40, and your interaction with the instructor will vary at each.

Classes generally start with a warm up. In my experience, they throw you right in with running, jump squats and push-ups, because why waste precious HIIT minutes? The idea is to prime your body as quickly as possible for the workout to come, and an intense warm-up can do wonders for the brain and the body.

HIIT is designed to work the entire body in short, intense blasts, building rest into the workout to improve recovery time and allow the body to more easily access its fuel for the next round. It’s tremendously effective because it keeps the body guessing. “When is the next time I’m going to have to kick it into high gear?” Fuel reserves remain more readily available during and after HIIT (in many situations, for up to eight hours afterwards) and your metabolism stays stoked.

In order to work the body in its entirety, HIIT relies on moves that recruit multiple muscle groups, often incorporating plyometrics and isometrics in addition to bursts of cardio. Think jumping switch lunges, plyometric push-ups, high-knee runs, and everyone’s favorite, the burpee. Depending on the studio, you may also use equipment in your HIIT class, alternating between kettlebells, jump ropes, free weights and boxes or steps. Part of the reason HIIT is so effective is its built-in variety!

The structure of HIIT classes is as varied as the moves. From day to day, the structure at the same gym may change, or you may sign up for HIIT at two studios and have remarkably different experiences. In general, expect a period of work followed by a period of rest, repeated across multiple sets with different moves for the duration of your workout.

One of the most common HIIT formats is Tabata — or 20 seconds work, 10 seconds rest, usually performed in sets of eight (so, four minutes).

Expect to jump or be provided with modifications if jumping isn’t your thing. Using your whole body, including your upward power, activates more muscles, so moves like these are common in HIIT.

Expect to be out of breath. The high-intensity piece is not a joke. You want to push yourself so your heart rate reaches 90%+.

Expect to sweat. HIIT is an awesome way to quickly and efficiently detox your blood (and provide it with a brand new batch of oxygen), in addition to your muscle cells, which will be able to regenerate and rebuild more effectively with a regular HIIT routine.

How to stretch
Ensure you include at least five minutes of whole-body stretching following a HIIT workout. Aim to work some length and some oxygen into your legs, back, abs, shoulders and arms, as well as circling out your head, neck, wrists and ankles.

When to go back
Because HIIT is so varied, you could technically take a HIIT class every day and cover your fitness bases in terms of cardio, strength and balance. The only thing lacking is steady-state endurance, although your whole system will build endurance from the sheer intensity of these workouts. Mix in HIIT a couple of times a week with yoga or a run, and take at least one day off to maximize recovery. Remember that recovery is integral to HIIT’s efficacy and taking time off — during and between workouts — is important.

Studio Recommendations 
Chaos Conditioning
Fit Forward

Mecca Gym & Spa
FIT Austin
Hiit Fit Gym

Beachfit Baltimore
Reflex Fitness
Aerial Fitness-Quarry Lake

BURN Fitness Studios
ABSolute Fitness

Madabolic Lake Norman
Crossfit Charlotte
Fast Fit Boxing

SWEAT Chicago
Shred415-North Shore
Sproing Sport Club

No Excuses UA
Aspire Circuit Training
Jackhammer Strength Training

Dallas Fit Body Bootcamp
Tread Fitness
CrossFit Deep-Ellum

Shift Cycle and Fitness
Fitness In the City
Evolution Fitness

The League – Heights
Studio Fitness Heights
290 Fitness

Kansas City
BodyFit Kansas City
JQ’s BFit2
City of Fountains CrossFit

Ten Health & Fitness – Hatton Garden
Outdoor HiiT

Las Vegas
My House Fitness – Las Vegas
Rhino CrossFit
Bodysport Fitness Center

Los Angeles
CrossFit Reflex
Malla Fitness
South Coast CrossFit

BodyTek Fitness – Wynwood
Da Factory Training Facility
Crossfit Yellow Falcon

CrossFit WorkHouse
Physical Culture(v)

Pro Vita
CrossFit 615
SHED Fitness

New York City
HIIT IT! by Daphnie Yang

Orange County
The 12 – Costa Mesa
HB Hits
Crossfit Body X

CrossFit Kings Point
SUBU Crossfit

CrossFit 267
CrossFit PHL

Bauman’s Xtreme Training
CrossFit Forbidden-Scottsdale
CrossFit Full Strength

Torque Strength and Conditioning
Adapt Training
Fulcrum Fitness

Bull City CrossFit
CrossFit Bullpen
ONE Fitness Training

BURN I.T Fitness Studio
The Academy

San Diego
Brian White Fitness
Versatile Fitness

San Francisco
Sweat Strength + Cycling – Oakland
FitFight Training Center

ModBody Fitness
Bassline Fitness
Get Fit! Bootcamp

St. Louis
Speed Play STL
Shred415-St. Louis
BURN 1000

U R CrossFit
Crossfit 428
Orangetheory Fitness- New Tampa

Ferris 360
The Fitness Girl

HIIT Fitness
Seva Fitness
Cloverdale CrossFit

Washington, D.C.
Sergeant’s Fitness Concepts
Elevate Interval Fitness
BlackBench Fit

Amy is a holistic health coach, triathlete and yogi living in San Francisco. She shares healthy living ideas and plant-based, gluten-free recipes at Follow her on Twitter and Instagram.