Reviewing a variety of interval training protocols (and yes, I share two with you here) to use for a new Flipping 50 Fit U program [designed for women who have more than 20 pounds to lose, and between 50 and 100 pounds is the sweet spot] I’ve been reminded of interesting phenomenon that continues to be buried in programming and marketing of fitness programs.
- There is more than one way to expend the same amount of energy in an exercise session.
- The choice of how to expend that energy impacts the outcome of the program.
- The choice of protocols dramatically impacts both risk of injury and drop out rate.
I invite you to examine these two interval training protocols:
- 4 minutes of high intensity interval training followed by 3 minutes of recovery x 4
- 1 minute of high intensity interval training followed by 1 minute or 1 minute and 30 seconds of recovery x 16
If you do the math (as I do as a conditioning coach) on volume of work the two protocols are identical. During each session you would be doing 16 minutes of high intensity exercise.
In a Journal of Strength and Conditioning Research published study comparing the two protocols, the energy expenditure had to be the same, so researchers had subjects do the 1-minute intervals at 94% of their max and the 4 minute intervals at 90% of their max.
To give you some relativity… you’re most likely to choose a level at about 60% to do steady state exercise. You’re intervals during a class or session might reach 85% if you can still talk through your breathlessness. In other words, 94% gets out of your comfort zone.
Most Effective Interval Training Protocol
If I asked you to guess –before reading further – which of these two protocols was most effective for increasing fat burning and energy expenditure… what would you say?
Actually, both are equally effective in boosting metabolism, fitness level, and perceived as fairly similar in intensity. Specifically, the longer intervals at 90% were more comfortable for subjects than 1-minute intervals at 94%. So while you might be thinking let’s get these things over with and do 1-minute bouts, because they’re so high intensity, you may prefer the 4-minute bout if you were held under heart rate conditions and your intensity were actually measured.
Should You Recover Between Intervals?
Short recovery between work intervals prevents complete glycogen restoration which is a part of the theory behind intervals. Depleting glycogen then supports the pathway that makes exercise more exhausting and thus increases fat burning afterward to restore. In a sense, you dig a deeper hole, it takes longer to fill it back up.
The high intensity of shorter intervals required to provide such post-exercise recovery makes exercise extremely uncomfortable. So much that before you might see results you would quit or be injured.
If you have over 20 pounds to lose, exercise itself, let alone high intensity exercise, is tricky to maneuver. Any trainer can tell you that you should be doing high intensity intervals but the 50% dropout rate still true of new exercisers suggests that self-selected exercise intensity especially if you’re more overweight, is a better way to stick to it. If you apply a specific intensity to your intervals as indicated by someone else vs. you self-select, the chance you’ll drop out rate is far greater.
A prime example of high intensity interval training is the popular Tabata intervals. Exercising hard for 20 seconds to recover for 10 seconds before repeating a total of 8 times in four minutes prevents real recovery. The research done on Tabata was done with elite cyclists (whose backsides are about as wide as a 2 x 4 and who spend hours cycling regularly up steep climbs). Few of us mere mortals choose to work that hard, or even are willing to when told this is the direct path to increased fat burning metabolism boosting.
Faulty Form, Faulty Results
By the time an exerciser – you or me – is at the 6th, 7th, or 8th repetition of the intervals – often doing exercise such as a “burpee” which requires zero creativity and prevents form and technique cueing – they have often lost good form. To pick on the burpee specifically, jumping to weight bearing on shoulders in a push up position, with head down to heart level then returning upright with a jump all the while under a zealous trainer’s coaching to go as fast as possible is an injury waiting to happen.
We’ve gone full circle. From large group exercise in the 80s to personal training in the 90s meant to get more specific and direct answers to clients’ questions, back to big boot camps and group training that focus on fast movements and Workout Of the Day (WOD), or posts to social media that list a series of exercises that you should do without every asking what your goals and status are and that suppose every one of us is the same.
History Repeating Itself with Interval Training
Twenty-five years ago research was looking at the use of arms during aerobic dance exercise. Did arm work falsely elevate heart rate? That was the question. In my estimation, a ‘burpee” falsely creates “work” that elevates heart rate with a flurry of activity without actually providing movement that has benefit to real life or that encourages good posture in getting to the floor or rising (the action of a burpee).
The same is true for boot camps that suggest you get strength and cardio in the same session. Moving quickly from one exercise to the next you are forced to reduce the amount of weight you lift compared to a focused strength training session. You may have an elevated heart rate but is it productive toward the goals you have? Or is it simply causing breathlessness and fatigue so you have the impression you’ve “worked hard?” And is it potentially setting you up for risk of injury by supporting more momentum. While you’re flipping tires are you being cued to use your legs and not your back, for instance? Or are you being encouraged to get the task done as quickly as possible?
I’d love to hear your thoughts. Have you begun interval training programs only to drop out? Have you experienced any increase in injury from participating in boot camps or fast- moving workouts? On the flip side, have you experienced good results?
If you or someone you know has a significant amount of weight to lose and you’re interested in applying to the beta group of Flipping 50’s Fit U send me an email. We’re launching in March to a limited number of women.