A UVA Heart & Vascular Center Initiative

Is HIIT Right for You? The Pros and Cons of High-Intensity Interval Training

Posted April 10, 2014

If you’ve seen the ads showing buff-bodied women and men hoisting giant barbells overhead, flipping tractor tires or doing one-armed push-ups, then you’re probably familiar with the high-intensity interval training (HIIT) trend. There’s no doubt HIIT can be taken to extremes. But toned down a notch, the basic premise of HIIT is actually right on target for some who want to improve fitness and build lean muscle mass.

“Physiologically, the combination of cardio and strength exercises in a high-intensity workout can be more beneficial to the body than cardio alone,” says Shannon Slovensky, M.Ed., exercise physiologist and researcher at the University of Virginia Exercise Physiology Core Lab . The key, as with any new exercise regimen, is to approach this type of workout wisely.

To help you determine if HIIT is right for you, we’ve asked Slovensky to answer some common questions and help us sort through the pros and cons.

What is HIIT?

HIIT article

High-intensity interval training is a workout that combines multiple short intervals of cardio, resistance and strength exercises, alternating them throughout a single session. HIIT-focused fitness centers have become popular in many communities. Workouts at these centers often involve functional, multi-directional moves, and challenges of balance, agility and power that traditional workouts may not have. For example, you might do a series of lunges, then a one-two-minute sprint, followed by box jumps or step-ups.

How does HIIT impact the body?

During high-intensity interval training, you work a variety of different muscle groups and perform short bursts of exercise at near-maximum effort. In an average jog, you might maintain a 13-14 on the RPE (rate of perceived exertion) scale . With HIIT, you are more likely to reach an 18 or 19 at certain intervals before dropping back down, explains Slovensky. “This spike and recovery pattern improves cardiorespiratory endurance and allows for a higher caloric expenditure, both during and afterwards, when compared with moderate aerobic exercise,” she says.

Who are the best candidates for HIIT?

Those considering HIIT should have:

o   A basic level of general strength, core strength and mobility

o   Body-awareness and knowledge of their own physical limitations

o   An interest in trying a variety of exercises

o   A doctor’s approval, if over age 55

o   Knowledge about how to perform the exercises correctly and safely, or
instruction by a qualified instructor who can provide guidance

o   No significant orthopedic limitations like back, knee or shoulder injuries

o   No cardiovascular problems, such as heart palpitations or high blood pressure

What are the pros?

Because the HIIT workout is higher intensity, you’ll burn more calories in a shorter period of time (more bang for your buck); and you’ll build lean muscle mass that boosts resting metabolism, which means the impact of your workout is longer lasting. A HIIT workout includes a variety of different exercises, so you’re less likely to get bored. When done in a group, the classes are typically small, so there’s a sense of camaraderie. And because the exercises are often timed, there’s also a bit of competition, which helps some stay motivated.

What are the cons?

HIIT is a strenuous workout that includes some not-so-safe exercises for those who are not physically fit, so the risk for injury is high. Positional changes can lead to dizziness or blood pooling in the lower extremities. Plus, doing too much too soon can cause excessive muscle soreness and, in extreme cases, rhabdomyolysis (the breakdown of muscle fibers that enter the bloodstream and poison the kidneys), explains Slovensky.

How can a beginner get the benefits of HIIT?

The key is to start slow and approach the workout at your own pace. That may mean trying interval training at home rather than signing up for a class right away. Here is an example of a cardio-strength interval workout you can try on your own:

Cardio-Strength Interval Workout

Duration: 20 minutes
Equipment required:
picnic table or sturdy table and chair, hand weights

Warm up: 3 to 5 minutes
Begin by doing a fast walk, shoulder rolls, side lunges or inchworm (bend forward, place hands on floor and then walk hands out to push-up position. Walk hands back toward feet and return to standing).  

Cardio segments
Examples include: running, fast walking, jumping jacks, high knee lifts, jumping rope. Choose the activity that helps you work at an intensity level you would classify as “hard to very hard” or a 15-17 on the RPE scale.

Strength segments
The goal is to do the strength exercises quickly to raise heart rate, while maintaining good form throughout. If using weights, choose a weight that puts you close to max fatigue at the end of 45 seconds.  

You have 15 seconds to transition between moves


Cardio ( 1 minute): for each cardio interval, choose one of the exercises listed above, such as running, jumping jacks, etc.
(45 seconds): squats. Stand in front of bench. Touch bottom to bench and stand back up. Repeat. (Hold dumbbells down by your sides for more intensity.)

Cardio (1 minute)
(45 seconds): push-ups with hands on top of the picnic table (easier) or on the bench (harder). Keep head above the heart and body in one long line (no sagging hips or bum sticking out).

Cardio (1 minute)
(45 seconds): step-ups. With RIGHT leg, stand in front of picnic bench and place entire right foot on bench and step up to tap left toe on bench, then step down. Repeat on same leg. (Hold hand weights for more intensity.)

Cardio (1 minute)

Strength (45 seconds): step-ups with LEFT leg (same as above with left foot on bench)

Cardio (1 minute)
(45 seconds): RIGHT bent-over row (place hand weight in right hand with the left knee and left hand on the bench.) Lift right hand towards side ribs and elbow toward sky until bent about 90 degrees.

Cardio (1 minute)
(45 seconds): LEFT bent-over row (place hand weight in left hand and right knee and right hand on bench) Lift left hand towards side ribs and elbow toward sky until bent about 90 degrees.

Cardio (1 minute)
(45 seconds): tricep dips. Facing away from table, sit down and rest hands on the bench. Walk your feet away from you until your bottom slides off the bench and you’re supporting yourself with your arms. Bend and straighten arms, lowering your body each time. (Place a weight in your lap for more resistance.)

Cardio (1 minute)
(2 minutes) Do an abdominal exercise of your choice, such as crunches or sit-ups.

Stretch and you’re DONE!


How Fit Are You?

To find out your current fitness level (cardiorespiratory fitness, body composition and more), contact the UVA Exercise Physiology Core Lab (EPCL) today to schedule an assessment. Call 434.982.3180 or email exlab@virginia.edu .

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