It's Worth (HI)IT - High Intensity Interval Training.

“The <insert any number less than 10> Minute Workout is all you need to have the body you’ve always wanted!” 

True?  Well, sort of – for some people, some of the time, and with varying results.  Nailing your best beach body with high intensity training is about as likely as using your travel points for the vacation of your dreams at the exact time you want it.  It can absolutely happen, but not without some careful planning (you’ve got to nail your diet) and clever strategery (your motivation game will need to be on point).  Also, your bag may or may not arrive (you’ve got to have great form/recovery to stay injury-free). 

Let’s face it, everyone wants more for less, and HIIT has become enormously popular in recent years because it does deliver results by largely trading intensity for volume.  HIIT workouts are highly versatile and conceptually straightforward, and there are incredible success stories across monster fitness brands like Crossfit, Barry’s Bootcamp, SoulCycle, P90X, etc. 

So what’s the secret sauce?  These workouts typically include short bouts (5sec-4mins) of intensity (>90% aerobic max) followed by brief recovery periods with weights, ropes, kettle bells, cardio equipment, and/or bodyweight movements.   

Let’s nerd out on what’s actually happening internally with HIIT (Figure 1):

There are plenty of scary words up there – I know. 

This is why HIIT is effective:

-       VO2max.  Your HR is going to fly increasing stroke volume (amount of blood pumped through the heart).  Healthy men and women of all ages can improve their cardio fitness by as much as 46% in training periods of less than 15 weeks.(1) As in, BOOM!  This is an enormous bang for your buck whether your goal is weight loss or athletic performance.  You should care about VO2max, as it not only determines your endurance capacity, but it’s one of the best predictors of cardiovascular disease – i.e. the #1 cause of death in America.

-       Calories.  You’re going to stoke the metabolic monster – as in, kcals en fuego. 

-       The Silent Killers.  Your blood pressure and cholesterol (HDL) will improve, not to mention improved insulin sensitivity.  These changes will require a little diligence to clean eating and a longer-term commitment to consistency within your HIIT programming (> 8-10 weeks).(1)

-       Fat.  Your fight or flight hormones are going to surge which has been shown to drive fat breakdown (lipolysis).(2)   Marked changes in body fat percentages require clean eating (surprise!) and a commitment to regular programming (>12 weeks). 

Why isn’t HIIT bulletproof?

-       Intensity.  As a cPT, it’s hard to tell people that they aren’t going hard enough – especially if they are feeling a little shaky and out of breath already.  It’s even harder to ACTUALLY go that hard.  A heart rate monitor (~$40) is your best accountability tool for the proper intensity level.

-       Consistency.  This typically is the issue for most individuals who aren’t getting results, but long-term changes require a LONG-TERM commitment.  It never ceases to amaze me when an individual who has neglected his/her health for 10 years suddenly expects to see results in 10 days.  Crossfit preaches community – almost to a cult-like cadence.  But guess what?  Community = Accountability = Consistency.

-       Nutrition.  Volume-based athletes can get away with some sloppy nutrition habits.  I did for years… balancing “whatever I wanted” with 20-25 hours of aerobic training/week.  This doesn’t work as well with HIIT.  You have to revise your philosophy on food if you’re truly looking to fast track results.  Think “unrefined” and “in moderation,” and you’re likely headed in the right direction. 

-       Injuries.  Ouch – this one is the toughest.  Unfortunately, to the untrained eye or to a newer athlete, speed can hide quite a few evils in terms of movement.  Any sort of pre-existing muscular/skeletal imbalances or abnormalities will only be amplified when you’re going ALL OUT.  Repeating poor movement patterns is literally the recipe for injury.

Final words:  HIIT can fit into everyone’s training. 

Hit intensity interval training is a metabolic winner.  You will get the results that you want with smart and specific programming (FUN helps, too!), and likely quite a few long-term health benefits that may not currently be on your radar.  You can, however, fail – and fail BIG.  Refuse to get discouraged and remember, there are plenty of folks like me who can help! 



(1) Kessler, H.S., Sisson, S.B., & Short, K.R. 2012. The potential for high-intensity interval training to reduce cardiometabolic disease risk. Sports Medicine, 42 (6), 489–509.

(2) Boutcher, S.H. 2011. High-intensity intermittent exercise and fat loss. Journal of Obesity, doi: 10.1155/2011/868305.



Kate Ligler