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Duke Researcher Claims Resistance Training Not Very Good At Burning Fat

A new research study conducted by Duke University and set to be published in the December 2012 issue of the Journal of Applied Physiology reports that aerobic training may very well be the best form of exercise for fat loss. Oh really?

After several previous studies showed little change on body composition from “aerobic only” exercise routines, now we’ve got this research study that claims it may be the most efficient and effective. So what are we to believe?

In today’s post we’ll dig into this subject and see what we can uncover.

More after the jump…

Alright let’s first take a look at the details regarding the study.

Duke researchers enrolled 234 overweight or obese adults and randomly assigned them to one of three different exercise training groups.

  • Aerobic exercise only
  • Resistance exercise only
  • Aerobic and resistance exercise combined

The aerobic exercise group is reported to have completed 12 miles per week. The resistance training group is reported to have completed three sets per day (8-12 repetitions), 3 times per week. The combined group did both routines.

All exercise sessions were supervised in order to accurately measure adherence among test participants. Interestingly only 119 out of the original 234 enrolled completed the study. Talk about a drop out rate.

According to the study abstract, the exercise routines were completed over an 8 month period.

Here’s what they found…

The aerobic and aerobic plus resistance groups lost more weight than those who just did resistance training. How much weight on average these individuals lost is unclear at this time.

The researchers did note however that the “resistance training only” group actually gained weight during the study due to an increase in lean body mass.

The following quotes are attributed to Cris A Slentz PhD,  and Leslie H. Willis, MS, exercise physiologists at Duke Medicine and the study’s lead co-authors.

“Balancing time commitments against health benefits, our study suggests that aerobic exercise is the best option for reducing fat mass and body mass,” said Cris A. Slentz, PhD, a Duke exercise physiologist and study co-author. “It’s not that resistance training isn’t good for you; it’s just not very good at burning fat.”

“No one type of exercise will be best for every health benefit,” Willis added. “However, it might be time to reconsider the conventional wisdom that resistance training alone can induce changes in body mass or fat mass due to an increase in metabolism, as our study found no change.” Go to source.

Digging a little deeper…

While research is certainly valuable for fitness professionals in assigning the most effective, safest, and time efficient forms of exercise to their clients, this study seems to leave more questions than answers.

Here in the real world working specifically with weight loss clients for over a decade, I’ve personally found that resistance training PLUS aerobic exercise PLUS diet modification to be the best protocol for body composition change. All three components playing a synergistic role, all equally important.

There is no mention of diet modification in this study and it’s uncertain if any was provided. My hunch is that it was not.

One of the conclusions of this study was that aerobic exercise may be a more “time-efficient” form of exercise compared to resistance training.

They noted that the aerobic exercise group spent on average 133 minutes a week training (spread out over 3 x week – approximately 45 minutes per workout) and lost weight, while the resistance training group spent on average 180 minutes per week (spread out over 3 x week- approximately 60 minutes per workout) and didn’t lose weight.

A few questions come to mind right out of the gate. Remember the researchers claimed the aerobic exercise group completed 12 miles per week. If we do some math on this we can conclude they did 4 miles of aerboic exercise per workout during the 45 minute session.

This comes out to be roughly 11 minutes per mile. So what exactly where they doing to complete the aerobic exercise at 11 minutes per mile?

While I don’t have an answer for that, if we are to assume it was aerobic exercise on a treadmill we’d be talking about a pretty good clip, at over 5 mph. Regardless we’re talking about a pretty high MET or workload for an obese individual to cover 4 miles in 45 minutes.

Depending on the exercise modality used, now we’re getting into concerns over joint compression and risk of overuse injuries. Let’s just assume for a second the exercise modality used was non-plyometric and didn’t provide joint compression like with a stationary bike, elliptical, etc.

There’s going to be a decent amount of caloric expenditure with an obese individual working at this level of intensity.

Was there any measurement of MET’s or energy expenditure measured with the resistance training to make this an apples to apples comparison? I have no clear cut answers, but again my hunch is there was not.

The point is what kind of impact could we really expect from some research monitored resistance training protocol of 3 sets of the same exercises for 8-12 reps over an 8 month period?

I’m seeing images of someone doing a leg extension for 3 sets of 10 reps with a guy in a white coat and a clipboard behind him/her counting reps.

Do you see where I’m heading with all of this? There are a lot of variables which researchers would want to leave out for the efficacy of their research, but none-the-less should and would be included in the real world.

Ideally the intensity and workload of resistance training sessions would be increased over time. This would influence not only caloric expenditure but also more importantly the metabolic disturbances placed on the body (ex. hormonal responses, etc).

This is one of the reasons I’m such a proponent of burst training for resistance exercise. Not that an obese individual would start exercising with burst training mind you, but rather the objective would be to work up to it.

The limitation with aerobic exercise only routines is the inability to produce much of a metabolic disturbance on the body. Sure there is caloric expenditure during the exercise session, but not much afterwards. I don’t want to turn this into a merry go round debate on EPOC and calories burned during and after with different forms of training.

Let me just say that in real world applications obese individuals in my experience tend to see better results when a combination of resistance training and aerobic training is incorporated WITH progression towards higher intensities.

The idea is NOT to continually spend large amounts of time with both routines, but rather decrease time as intensity increases. In short, we’re looking to do more work in less time as far as resistance training goes.

I won’t argue that n0n-plyometric aerobic exercise that is low intensity and completed for longer durations (45-60 minutes), has a very valuable role in helping obese individuals produce a change in body composition.

However, a key component here is that we’re talking about aerobic exercise that does NOT produce joint compression. Jogging on a treadmill at 5 mph is most definitely a plyometric movement that produces a significant amount of joint compression on the ankles, knees, hips, and low back.

I do NOT and repeat, do NOT recommend this for obese individuals.

Fitness professionals and the exercisers themselves need to be aware of the risk versus reward with any form of training.

Picking up exercises and routines from the TV show the “Biggest Loser” is a bad idea. I don’t even want to get on my soapbox about this.

Wrapping this up, I’ll just say that exercise as it pertains to body composition change doesn’t fit nice and neatly into a box for research purposes. It should be ever-changing and progressing as the individual adapts to the workloads placed on him/her.

Always best to start with proper movement and mobility first, before progressing to higher intensity exercises. In short the training should be smart in order to be BOTH safe and effective for the client.

If you’re a fitness professional I’d encourage you to read the six part series by fat loss guru Lyle McDonald on “Training the Obese Beginner.” This will provide some insight on the needs of obese individuals.

And for heaven’s sake no matter what you do, please don’t go out and recommend your overweight and obese clients to be doing sprints, box jumps, jogging, or anything plyometric in nature.

The debate is certain to continue over what type of exercise is BEST for burning fat. Instead of arguing over results from controlled research studies, we need to continue putting protocols to practice in the real world.

While I don’t have a PhD degree, as a fitness professional who makes a living in the trenches I’ll make a case to respectfully argue the point that resistance training is not very good at burning fat.

We just won’t be doing it in some lab under assigned sets and reps, but rather with good old fashioned sweat and effort under the iron.

Reference:

L. H. Willis, C. A. Slentz, L. A. Bateman, A. T. Shields, L. W. Piner, C. W. Bales, J. A. Houmard, W. E. Kraus. Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. Journal of Applied Physiology, 2012; 113 (12): 1831
DOI: 10.1152/japplphysiol.01370.2011

Shane Doll is a certified personal trainer, fat loss expert, speaker, and founder of Shaping Concepts Fitness Training Studios. If you’re looking for a personal trainer in Charleston, you can receive a no-obligations personal training trial and consultation without risking a dime. Over 1000 Charleston area residents have transformed their bodies following our unique burst training workouts and simplified nutrition programs. Experience the Shaping Concepts difference today.

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Category: Fat Loss.