You’re pressed for time.  You know you shouldn’t blow off your plan to workout today, but you can’t fit in a whole hour.  Maybe you can squeeze in 30 minutes.  Does this scenario sound familiar?  So what’s the best use of your time if improved fitness and maximum calorie burn are your goals:  Weight training or cardio?

If you said cardio, guess again.  It appears that a weight training circuit packs the strongest punch compared to hopping on a cardio machine for an aerobic workout.  A weight training (a.k.a. resistance training) circuit, if you’re new to fitness vernacular, is when you go from one exercise to the next, taking as little time as possible to rest in between.  An aerobic (a.k.a. cardio) workout is something you can do at a sustained level for a relatively long time without fatiguing, such as jogging, cycling, swimming, brisk walking, etc.  What these aerobic activities have in common is that they use the body’s larger muscles which can perform work longer without fatiguing.

If you’ve been following fitness trends for a while, you’ve probably already heard that the best way to improve your fitness during your cardio workout is by adding intervals, or high intensity bouts to your activity (i.e. alternating between one minute of slow and fast jogging) instead of just staying at a “steady state.”  It’s been shown that you can burn a similar amount of calories by doing a shorter workout with intervals as you would in a longer, lower intensity workout.¹ (Note to people trying to lose weight:  Please stop believing people who tell you that low intensity workouts burn more fat.  That’s so wrong!)

As a matter of fact, the harder you do intervals, the greater the benefit to your fitness and the more calories you burn, if you’re not a newbie.  Much research has come out in the past decade touting the benefits HIIT (high intensity interval training) has on improving endurance, burning fat and building strength.  If you’ve ever done Boot Camp workouts, Indoor Cycling (Spinning) classes or DVDs like “Insanity,” you’ve probably done some HIITs.  Some more recent studies have shown that this type of workout can make you lean and mean in less time than steady “state endurance training” (doing cardio at a steady pace for 20 minutes to an hour),² making HIIT the Holy Grail for us trainers trying to get our clients fitter, faster.

But hold everything!  There may be a new bad boy on the block to give you even more bang for you exercise buck.  Well, the information isn’t exactly new, but in lieu of all the HIIT hoopla going around the past several years, this research bears repeating, especially since it may be even more calorie torching than doing intervals.  I’m referring to good ol’ pumping iron.  But not the kind where you do one set, then rest and chat with your buddy, then pick up the weights again.  I’m talking circuit weight training where you go from one exercise to the next using resistance that is relatively challenging to downright heavy with minimal rest in between sets.  This type of vigorous weight lifting has a positive effect on a little something known as the EPOC. EPOC stands for “excess postexercise oxygen consumption” which is the technical term for what’s commonly called the “after burn.”

Exercise scientists have known for a while that the harder and more intense your workout is, the longer your body will be in an elevated metabolic state.  This means for a while after your workout session, your body continues to burn more calories at a higher rate than if you hadn’t gotten off your couch to exercise.  The amount of extra calories isn’t a whole lot (approximately 51 – 127 extra calories according to two different studies), but over time it adds up and can help in your weight management plan.

The EPOC, or afterburn, is greatest after high-intensity resistance exercise because the body needs extra energy to restore itself and return to it’s normal state.   This energy of course, comes from calories.  Most of the studies on this have been on men, but compelling results were also found in a small study done on women and published in 2000.  Researchers studied seven females (average age of 27 years) and had them perform a workout consisting of five supersets (10 exercises) doing 10 – 15 repetitions per set.  In case you want to give it a go yourself, the exercises were:  bench press and bent-over rows; leg extension and leg curl; military press and sit-ups; biceps curls and triceps extension; and lunges and lateral raises.  They were given four minutes to complete the workout.

After the workout the scientists measured the subjects’ EPOC every 30 minutes.  Three hours after the workout, they found the EPOC was still 13% higher than their pre-exercise metabolic rate and even 16 hours after the exercise, their metabolisms were still 4.2 percent higher than their pre-workout resting metabolic rates.  The authors’ conclusion is that intense resistance training produces a prolonged but modest elevation in post exercise metabolism in women.

The moral to the story is if you’re short on time, is you can still get results by doing short, more intense workouts.  If you’re doing cardio, add high intensity intervals to rev up your metabolism.  Or better yet, do a circuit of weights heavy enough to be somewhat to very challenging (not comfortable) and you can get an even more after burn.  The more intense the workout, the longer and greater the after burn.  So, if your still making excuses that you have no time, you can stop now!  It’s probably not so much time that’s your issue, it’s probably motivation.  How do you get motivated?  Well, Spring is upon us and skin will be showing.  Pull out your skinny jeans or a picture of yourself (as an adult) when you were in great shape and put it where you will see it regularly.  Or, hire a trainer willing to do short sessions with you or who will just write some out workouts you can follow on your own time.

Reference:

1 & 2.  Kravitz, Len & Zuhl, Micha, 2012  HIIT vs. Continuous Endurance Training:  Battle of the Aerobic Titans.  IDEA Fitness Journal, 9 (2) 34-40