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  • Ingri Pauline

Why Your HIIT Class isn't Changing Your Body

Most women start exercising for a change in body composition. This goal is to lose fat and build muscle. They sometimes don’t know this is what they are looking for. Their goals sound like “I want to tone up,” “I want to look like this fitness model,” I want to lose weight,” or “I want to lose 10 pounds.” All of these goals are pretty elusive, besides that last one. That’s a good, measurable goal but also has its flaws.

The one thing all of these goals boils down to is these women want to lose fat and build muscle, changing the composition and shape of their body. FULL STOP.

I see many women repeatedly going to yoga, Zumba and HIIT classes but never seeing any results to show for. Ok, diet is one issue but really you exercise method is another huge one you are not looking at.

from PopSugar

In order to build muscle that leads to more fat loss you have to stress the muscle. This best come in short bursts. Explosive lifting, found in powerlifting, olympic lifting, CrossFit and sprinting are usually your best bets to build muscle and burn fat.

But do you you that at your gym classes? Probably not.

Many people will want to do a quick “finisher” on their lifting session, wanting to get a good sweat and burn some fat. But these “finishes” last 20 or 30 minutes! Many will go to a HIIT class, or high intensity interval training, class and expect to “torch the cals!” and change your body. I've seen these classes last 40-60 minutes and 80% of the time the people are moving. Most are 30 minutes and do a 1:1 or 2:1 work to rest ratio. But keep in mind, these are not changing your body composition but just burning calories. Sounds good but usually it just makes you hungry and feel like you’ve “earned” a treat.

If I was running a HIIT class, you folks would be running 100m every 5 minutes. Doing sets of weighted jumping lunges and hanging out recovering for 40 or 50 minutes of an hour.


Because muscle and speed are developed when you are rested enough to give it your FULL EFFORT. If you are working out for 40 minutes taking the intensity up and down within 2 minute intervals you are essentially doing and endurance workout and NOT working to in you full power or full capacity rage. You are working out your survival, long distance muscle. And those don’t get very big, pretty or burn a lot of fat.

When you give a burst of power and energy, like going a 200m sprint or deadlifting 180 lbs five times, you need time to recover before you can do it all over again. This is the ATP-PCr energy system. It is quickly used up and take at least two minutes of rest to refill the tank so you can go at it again.

This is why sprinters workout in a 1:3-8 work to rest ratio. If you are running for one minute, you should be resting 3-8 minutes in between sets. And I mean resting. Not “low intensity” mountain climbers or shuffling back and forth in a lunge.

This is the same thing with weightlifters. It is better to rest longer in between heavy sets so you can go HAM on each and every set. This will recruit more muscle fibers to work and beget more muscle.

If you are looking to build muscle and shape on your legs and you are doing plyometrics (explosive jumping) you are better to do small sets of less than 10 reps and rest 2-4 minutes in between sets. Do yourself a favor and grab a 25lbs plate and jump with all your might. Then FULLY recover and do it for a few sets.

This will help you change your body composition more 30 or 40 or 60 minutes of continuous and stressful activity. The best workouts allow for a full recovery and full effort. This short bursts of activity.

If you only have 30 minutes to workout, there are great options. You can do a series of burst and rest. Have a timer go off every 5 minutes for 30 minutes and run through a quick, 1 minute barbell, dumbell, kettlebell, plyo or calisthenic circuit. Make sure you are working at max capacity and feeling the lung burn. Then rest.

Or you can do a series if hill sprints or one or two CrossFit workouts that take less than 5 minutes to get through and follow it with some planks.

No matter what you should leave feeling refreshed and strong, not gassed and spent.

Those sweat classes do have a place and it’s usually once or twice a week coupled with a lifting program. Just don’t be fooled that it will transform your body or bring you towards your goals.

HIIT classes are a great way of training your cardiovascular system and I am a huge fan of this. I tend to think most women who work and workout don't need a high stress class everyday. Many will benefit from meditative quality that comes with weightlifting most days of the week.

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