“Trained” females!
If you’re like me, then you want to know things like how many calories does weight lifting really burn? And, I’ve heard a lot about this weirdly named thing called “EPOC”, but I wonder how many calories it really burns. If you’re anything like me AND a you’re a female, then you’ll also be thinking, what about for women?
Well, the study that I’ll discuss today looks at just those questions. This is from Binzen, et al., 2001, and is titled, Postexercise oxygen consumption and substrate use after resistance exercise in women. Other studies before and after this one have shown that interval and higher intensity exercises cause people to burn more calories (kcals) in the hours after the exercise session. The study today sought to measure how many kcals women burn while they do resistance exercises and in the hours after the session. I love empirical research-based info on stuff like this. This puts factual numbers to these concepts that we’ve seen thrown around online so much.
Methods
The participants in the study were 10 females, averaging 29 years old. Below is a chart of their descriptive stats. The researchers used “trained” women for this study and, interestingly, used the results of their VO2 max test to confirm their athletic status.
Descriptive data for Binzen, et al. 2001
For the testing, each woman had her resting energy expenditure measured. Metabolic rate was measured while each sat quietly, then while each performed a resistance exercise session, and while each sat for 2 hours following the session. Metabolic rate was also measured separately for 2 hours while each did nothing. That acted as the controlled comparison to the 2 hours following a lifting session.
The researchers also looked at the ratio of fat vs carbohydrates burned after the lifting session, which can be determined from the data gathered from the same device measuring metabolic rate.
I’ve had my energy expenditure measured, both at rest and while active up to my VO2 max (on both a treadmill and a stationary bike). The gist is that you wear a mask that covers your mouth and nose. The mask is connected to a device that measures the oxygen you breath in and the carbon dioxide you exhale. That info is used to calculate your energy expenditure, aka how many kcals you burn. The device that the mask connects to can be placed on a cart to allow researchers to move with the participants throughout a study session. I will discuss a study in a future post in which this mobility is important.
For the lifting session, the women did 10 exercises. Each exercise was done for 3 sets of 10 repetitions of 70% 1RM, with 1 minute of rest between each set. They had the mask on for the entire session and for 2 hours following the session while they sat and rested.
Results
The total average kcals burned after sitting for 45 minutes was 50. The total average kcals burned after a 45 minute session of resistance exercise was 155. Their 45 minute lifting session burned 105 kcals more than if they just sat around. The women did work for only 15 minutes and rested for 30 minutes of the session. They burned an extra 105 kcals for only 15 minutes of effort!
The only difference in the energy expenditure for the two hours following the lifting session was during the first portion. In the first 60 minutes following the lifting session, they burned an extra 25 kcals…
Last, the researchers looked at how much fat vs carbohydrates provided the kcals during the EPOC period after the lifting session. The analysis of the data showed that, on average, 79% of the kcals burned were from fat and 21% were from glycogen (aka sugar aka carbs).
Implications / Thoughts
I have regularly found in studies that the energy expended during resistance exercise sessions comes from working only a third or less of the time. The rest of the time spent in a lifting session is sitting around resting. Of course, you could do something (a la supersets or some synergistic thing). I’m lazy, myself, and prefer to spend my rest time…actually resting.
Don’t let this one study be your only take on EPOC. I will get into EPOC results from other studies in future posts. Remember that the weight of the evidence must guide our views on these things. You don’t want to over generalize these results. This is but one study of one type of training with one group of participants. Change any aspect and the EPOC results could be very different. In future posts, we’ll see what happens under different conditions.
Last, the burning of 105 kcals may not seem like much, but remember the context. That was from 15 minutes of work. As well, there is not just one type of resistance exercise. Different programs with different intensities will result in different energy expenditure. Granted, let’s not kid ourselves. Plenty of people just do 1-3 sets of 10 reps that are ~50-80% 1RM kinda weights for each exercise. For those lifters who are females within this demographic, these study results may very well align with their results. For others, though, results may vary.
In Conclusion
I was intrigued with these results. While they’re not out of this world, they’re real world results. Don’t think that because you just had a lifting session you can go have a big meal or a large muffin with a coffee. You may not have burned off as many kcals as you think you did.
I think these results can push us to either do more work when we lift or they can push us toward the many other reasons to do resistance exercise. Other studies, that I will review in time, point out all of the other benefits of resistance exercise: strength, functionality in life and into old age, lean body composition, improved glucose metabolism, increased bone mineral density, etc. There are other options for burning kcals if that’s what you desire. Resistance exercise sessions that are not higher in intensity may well be better thought of as helping your overall health and wellness.
If you have any questions about this study or anything I said, please feel free to leave a comment. I will get back to you and others may have insight to offer, too. If you have any questions or topic suggestions that you would like answered as a post, then please email me at robert@analyticfitness.com.
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