The short answer: Not more than an hour. But it's what you do that matters most, especially if you want to burn fat or change your body.

The long answer: Here you go...

I used to teach Spinning classes. Part of the certification curriculum was understanding heart rate zones and how our body responded when in those zones. Was our body burning fat? Was it tapping into any carbs/sugar we had on reserve? Was our body building lactic acid, creating that burning feeling in our muscles? Or was it just coasting along not doing much more than "recover"?

I spent A LOT of time over the years preaching that the best place to workout was in our "fat burning zone," or right around 70% of our maximum heart rate (give or take). In theory, the more time we spent in that zone, whether it was 45 minutes or 4.5 hours, we'd burn fat. Of course, the notion among people who wanted to lose weight was that they just needed to work at a level that was kind of challenging, but still conversational. If you weren't able to have a conversation at the pace at which you were exercising, you were working too hard. If you worked too hard, you stopped burning fat.

Now, I have to say I still love Spinning. Love it. But if I ever went back to teaching again, I'd do it differently - and almost surely get results.

Long, Slow Cardio
We all know the benefits of exercise are endless, and there is no doubt we all want to be healthy, but finding the time to workout can be challenging. What's more, a great many people who exercise simply for the sake of shaping up or losing weight come face-to-face with the how much they have to do before they actually start seeing results.

The upside of slow and steady cardio is that it improves the way our muscles use oxygen, it decreases our risk of heart attack or stroke and it could help decrease body fat. The downside of the long, slow work is that it takes time and can be boring. The reason I say it could decrease body fat is because there is growing research that suggests long, slow cardio actually eats away at our muscles store and might increase fat stores.

Less is More
If you had the choice of working out for 45 minutes or working out for 90 minutes - getting the same results - which would you choose?

A study published in the Journal of Applied Physiology showed the ability to burn fat increased by 36% after an hour of short interval training. What's more, cardiovascular fitness increased by 13%. The group of women studied varied from moderately fit to borderline sedentary. This group's workout was made up of ten sets of four-minute bursts with two minutes of rest in between (total time = 58 minutes). A second study from McMaster University showed great benefits by doing ten intervals for one minute with one minute rest (total time = 20 minutes).Much research is being done now to help understand how interval training can help those with metabolic diseases, like diabetes.

Higher intensity intervals have been shown to yield equal or greater results in a significantly shorter period of time in comparison to slower "endurance" work. While it's certainly beneficial for athletes in training to put the miles in so their body adapts, the everyday average person who just wants to get into better shape or lose weight does not need to workout for hours a day. In fact, if the quality of exercise is great, the quantity can be significantly less.

What Workout Will Get Results?
Quality is defined by intensity, and intensity is defined by how hard you push yourself. The studies above reference short one to four minute intervals repeated about ten times with a short break in between.  The people used in these studies weren't elite athletes, but they did push themselves to between 90 and 95% of their maximum heart rate.

Here is a sample workout you can do anywhere (on a run, on a bike, in a pool, on an elliptical, on a stairmaster - if you can move on it, you can use it for interval training). The key is in pushing yourself very hard. You already know what it feels like to do the same-old, same-old. This is more intense, but shorter. It's also a little more fun and makes you feel good when you're done!

Simple 25-Minute Workout (that kicks butt!)
Warm Up for a few minutes
3 Minutes High Intensity
1 Minute Rest
4 Minutes High Intensity
1 Minute Rest
5 Minutes High Intensity
1 Minute Rest
4 Minutes High Intensity
1 Minute Rest
3 Minutes High Intensity
1 Minute Rest
1 Minute All Out Pace
You're done!

Want something more colorful or more structured? I wrote an ebook called 20 High Intensity Workouts to a Great Body. It's a handbook of great workouts and  available on Amazon right now for 2.99. It's there for the taking if you want it.

I also created a program called The 40 Day Shape Up. It combines high intensity workouts with a diet plan that resets your metabolism. I love the results so far, and I'd love to work with you on it! It's less than $2 a day ($79) and quite the steal.


Want more tips like this? Traci D Mitchell is a healthy living and fitness expert. Follow Traci on Facebook. She’d love to see you there! Interested in working with Traci? She works privately with clients specializes in nutrition coaching and weight loss as well as functional fitness and personal training. All sessions are done via Skype or telephone if outside of Chicago. For more information, contact Traci here.

Looking for a simple way to get into great shape and eat right? Try Traci’s 40-Day Shape Up!


Jonathan P Little, Adeel S Safdar, Geoffrey P Wilkin, Mark a Tarnopolsky, and Martin J Gibala. A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanismsThe Journal of Physiology, 2010; DOI: 10.1113/jphysiol.2009.181743

University Of Guelph (2007, June 27). Interval Training Burns More Fat, Increases Fitness, Study Finds. ScienceDaily. Retrieved July 4, 2012, from­/releases/2007/06/070627140103.htm