All About High Intensity Interval Training
A fitness protocol proven to make you stronger and faster
Chances are you’ve heard of High Intensity Interval Training, also known as HIIT. It’s a cardiovascular exercise strategy alternating short periods of intense anaerobic exercise with less intense aerobic recovery periods.
In other words, you exercise with utmost intensity for a short amount of time, usually 30–60 seconds, then recover for a longer period of time, usually 2–4 minutes. This intense burst of activity + recovery period = 1 interval.
HIIT is key when it comes to boosting endurance, increasing metabolism, regulating insulin levels and losing body fat.
“All exercise helps burn fat by burning calories,” notes fitness expert Rob Sulaver. “More intense exercise burns more fat. It’ll also improve your endurance, complement your strength development and help you get shredded.”
Here’s an example:
Warmup 5–7 minutes with an easy jog
30 second CONTROLLED sprint near maximum effort
2–3 minutes of walking or easy jogging to catch your breath
Repeat this process 8 times
Cool down 5–7 minutes with an easy jog or walk
HIIT can apply to any training modality including weightlifting, swimming, and boxing to name a few, with training sessions generally lasting anywhere from 20 – 45 minutes. Whatever your sport / workout / activity of choice, there is a way to incorporate HIIT.
Let’s break down the example above to understand why HIIT is so effective.
According to heart rate training expert Dr. Declan Connolly, “people should not even attempt HIIT training unless they’re already fairly fit and / or have 12–16 weeks of consistent training under their belt.”
Be careful.
Warmup 5–7 minutes with an easy jog
Warmups are critical for maximum performance and injury prevention. Performing sprints near maximum effort on muscles that are “cold” (not warmed up) often leads to muscle pulls and connective tissue strains. Warmups prime your body for the effort to come by increasing core temperature, circulation and respiration, elevating your heart rate and loosening up muscle tissue.
If sprints are on the agenda, jogging or biking are excellent ways to warm up. If you’re boxing, try jumping rope. If you’re swimming, well, swimming is probably best. Anything that gets the blood moving and puts you in the right head space to perform your training as safely and effectively as possible.
30 second CONTROLLED sprint near maximum effort
Like a car at 8000 rpm, your body should be in the red — reaching hard for air, heart pounding, legs churning, unable to hold a conversation, counting the seconds until you can stop. You’re teetering on the edge, running all out while still maintaining form.
This is what a controlled sprint looks like.
Start strong, stay strong, end strong. This is my mantra during training. The sprint will not feel comfortable, but should not feel unpleasant either. Don’t allow your form to break down. Keep your abs tight. Head up. Shoulders forward.
Focus on gliding over the terrain rather than pulling yourself forward. When you reach the 30 second mark, don’t stop all at once. Let your body naturally slow down into your recovery walk or jog.
The goal of your effort is to raise your heart rate as high as possible, ideally 85% of your maximum heart rate (MHR). To calculate your MHR, Dr. Bryant Walrod of Ohio State suggests using his quick calculation method: 208 — (.7 x age). “This formula tends to be more accurate than 220 minus age, especially as you get older,” Walrod states.
Three minutes of walking or easy jogging to catch your breath
Read: easy jog. The secret to HIIT is in the recovery between sprints. Your heart rate should come down as quickly as possible, to roughly 55–60% of your MHR. The difference between your heart rate during the sprint and your heart rate during recovery is the “interval” part of interval training.
Forcing your body to repeatedly acclimate between two very different states provides excellent cardio conditioning while accelerating fat loss.
“When the body works to adapt from the anaerobic (high-intensity) period to the low-intensity, aerobic recovery period in HIIT, this workload results in high caloric expenditure, which can lead to fat loss,” explains Franci Cohen, exercise physiologist. “The rest periods are needed to prep the body and enable it to truly perform at its max during the high-intensity spurts.”
You might need to walk or extend the jog the first few sessions — I sometimes jog half and walk half. The goal is to be able to run the subsequent intervals strong and finish the workout fatigued, but not completely spent.
Repeat this process 8 times
For beginners, if 8 seems like too many, start with 6. You’ll build up over time as endurance improves. For you rock stars, you may want to push to as many as 12. Nothing is set in stone — go with how your body feels. I often don’t determine exactly how many intervals I’ll perform until I’m well into the workout.
Cool down with a 5–7 minute easy jog or walk
A cool down is exactly what it sounds like: a gradual cooling of the body post-exercise to bring the body back to steady state. Heart rate decreases. Body temperature lowers. Muscle fibers return to their optimal length-tension relationships (resting tension, length and elasticity levels).
Cool downs also help prevent fainting or dizziness, which can result from blood pooling in the large muscles of the legs when intense activity is stopped, along with removing waste products from your muscles, like lactic acid. Lactic acid build ups during vigorous activity (responsible for the burning sensation you feel during exercise), and is most effectively removed by gentle movement rather than stopping suddenly.
Be ready for, well, intensity
High Intensity Interval Training workouts are, as the name suggests, intense. Dialed up to 11 intense. That shouldn’t scare you, that should excite you!
HIIT workouts will bring a new element to your fitness, delivering new power and energy to your body. It’ll get stronger and more durable. You’ll run faster and longer. Able to leap taller and taller buildings.
As your fitness improves, play with your timing a bit. Up your sprint from 30 seconds to 60 seconds to 90 seconds. Shorten your recovery from 3 minutes to 2 minutes. Up your interval count from 8, to 10, to 12. As I said, nothing is set in stone. And of course, make sure to never skip the initial warm-up and cool down periods.
Be strong, be safe, be well.
Scott Mayer is a runner, thinker, curious observer and certified personal trainer.
Photo courtesy of Leon Martinez on Pexels