Although strength training is meant to build muscle and/or get stronger, it also burns calories. But how much actually?
1. A 70 kg person burns an average of 100 (normal intensity) to 250 kcal (high intensity) with half an hour of strength training. You have to subtract the calories from this that you would have burned at rest (1 kcal / kg / hour), while you have to add the calories from the ‘afterburn’. After an hour of strength training, that afterburn is usually no more than 50-100 kcal.
2. For lean bulking you need to calculate your caloric maintenance level accurate. Therefore, do not use a general storage factor for sports, but calculate the calories of sports activities (walking, cardio, strength training) as accurately as possible. Then add that to your ‘bare’ maintenance level.
3. In bodybuilding, strength training is for building muscle, not fat loss. So don’t make your strength training while cutting into glorified cardio: keep training as much as possible at the intensity and volume you used in the bulk.
Whether you’re bulking or cutting, it’s important to know as precisely as possible how much energy you consume in a day. After all, during the bulk you have to maintain a small calorie surplus, during the cut a substantial calorie deficit. The use of a calorie app is therefore indispensable for natural bodybuilders.
DETERMINE CALORIES FROM STRENGTH TRAINING
Thanks to barcodes and kitchen scales, the calorific value of food is fairly easy to check. And with cardio, the energy consumption is often indicated on the device.
How much you burn with an hour of strength training, however, is a lot more difficult to determine. Strength training is an anaerobic activity, which basically consists of short bursts of intense movement followed by rest. In addition, you usually use different muscle groups during an hour of strength training. All this in contrast to most aerobic activities. When running, for instance, you use the same muscles in the same way for a continuous period.
Exactly how much energy you use during an hour of strength training depends on several variables:
- your body weight (you burn more if you are heavier);
- which muscle groups you train (large muscle groups, such as legs and buttocks, use more energy);
- the absolute intensity you use (heavy weights use more energy)*;
- the relative intensity you use (training close to muscle failure costs more energy);
- which exercises you do (compound exercises burn the most)**;
- how much volume you do (the more exercises/sets, the more you burn)***;
- which training program you do (you may burn more energy during a full body workout)****;
- the degree of metabolic stress (with strength training with short rest breaks and long sets you burn more);
- the duration of the training.
* ABSOLUTE INTENSITY
According to some studies, absolute intensity seems to play only a small role in energy consumption. For example, hardly any differences were found in energy expenditure between training with weights of 80%1RM and 55%1RM. This is probably because you have to do more repetitions with light weights to achieve muscle failure.
- bench press: 5 kcal per minute;
- push-ups: 8.56 kcal per minute;
- crunches: 4.09 kcal per minute;
- lunges: 9.33 kcal per minute;
- pull ups: 9.95 kcal per minute.
As you can see, even with ‘big’ exercises such as lunges and pull-ups, the energy consumption is not that big. Even if you do it non-stop for an hour (good luck!) you won’t burn as much as with most high-intensity cardio.
Of course you don’t do strength exercises in one go. You will probably rest for one to two minutes between most exercises.
A study by Haddock et al. shows the difference in energy expenditure between a strength training session of 9 sets (25 minutes) and 27 sets (66 minutes), namely ~235 kcal versus ~662 kcal. Please note: this is the energy expenditure on top of the resting metabolism, so excluding the energy that you would normally use at rest.
Strikingly enough, the so-called afterburn (see below) was approximately the same in both cases, namely ~95 kcal. Apparently the amount of training volume has relatively little influence on the amount of calories burned after training for recovery.
**** TRAINING PROGRAM
A study by Robergs et al. suggests that you expend more energy when you do a full body workout. They recorded a consumption of 10 to 12 kcal per minute if both the barbell squat and the barbell bench press were done in the same workout .
The American Harvard University published a list of the most common sporting and non-sporting activities and the associated average energy expenditure according to three different body weights.
Below are the results for three types of strength training: standard, intensive and circuit training. ‘Intensive’ should be interpreted broadly here: this can be, for example, large, compound exercises with high weights, but also isolating exercises with long sets and short rest times. The values for circuit training give you an idea of how much you burn if you do exercises more or less constantly, without rest breaks.
|Body weight||57 kg||70 kg||84 kg|
|General strength training (30 min.)||90 kcal||112 kcal||133 kcal|
|Strength training intensive (30 min.)||180 kcal||223 kcal||266 kcal|
|Circuit training (30 min.)||240 kcal||298 kcal||355 kcal|
How many calories you burn with a certain activity within a certain time frame does not say everything about its actual impact on your energy balance. You have to take the following corrections into account.
1. MET (METABOLIC EQUIVALENT OF TASK)
Please note that when calculating your energy balance, you should always assume extra calorie consumption from physical activity. According to the Harvard guidelines, if you burn 300 kcal with strength training, you should subtract the number of calories you would burn at rest – if you had been sitting on the couch for an hour instead of training, for example.
For a correct calculation, based on your body weight, you should use the MET (Metabolic Equivalent of Task) formula. One MET corresponds to an energy expenditure of 1 kcal / kg / hour, your energy expenditure at rest. A person weighing 70 kg therefore consumes 70 kcal during an hour of sitting on the couch. If instead he starts strength training for an hour at a reasonable intensity, he will burn (300 – 70 =) 230 kcal through that training. That does not include afterburn – see below.
2. METABOLIC ADAPTATION
Perhaps the net energy consumption of that hour of strength training will be even lower. If you train intensively for an hour every day, it is possible that your body will cut back on unconscious physical activity (NEAT) for the rest of the day, so that you burn less net. Therefore, estimate your energy consumption rather carefully, especially during the cut.
3. AFTERBURN EFFECT
Not only do you burn calories during strength training or cardio, but also after the activity your energy consumption will be somewhat higher than at rest. This is the so-called afterburn effect, officially called Excess Post-Exercise Oxygen Consumption (EPOC).
After physical exertion, your body replenishes oxygen, ATP and creatine stores, removes lactic acid and repairs muscle tissues. These are processes for which it needs oxygen, which increases the oxygen consumption and thus also the energy consumption.
The magnitude of the afterburn effect is often overestimated . Usually it is only 6-15% of the total calories burned during the activity. With strength training it is admittedly slightly larger than with cardio (with the exception of HIIT), but it is still quite limited. Although it lasts quite a long time, the extra energy consumption is limited: according to an Italian study, you burn an extra 88 kcal after a traditional strength training session for 22 hours. The previously mentioned study by Haddock et al. arrived at a comparable figure, namely ~95 kcal, regardless of a short or long training session (25 and 66 minutes respectively).
In our calculations we are therefore very economical with the addition of afterburn: we only add 50-100 kcal to strength training, depending on how intensively we have trained. Don’t forget that you already have a small calorie surplus in the bulk (~200-400 kcal); In principle, this also contains a piece of EPOC, namely the repair of muscle damage. In the example of just now, we would use a total of 300 kcal for that hour of strength training. On top of that, another 200-400 kcal are added as extra energy for muscle building.
Example with a 70 kg person:
You do 60 minutes of strength training and in the first half hour you do pull-ups and barbell rows , and in the second half hour you do reverse flyes and some isolating biceps exercises. Would you rather heavy for the first half hour 200 kcal can ignite the relatively light second hour 150 kcal. So a total of 350 kcal – still approximate.
In principle, this number also remains after the corrections (correction 2, the metabolic adjustment, let’s leave it for what it is). The energy consumption that you would normally have at rest (correction 1), 70 kcal, more or less corresponds to that of the afterburn (correction 3), also roughly estimated at 70 kcal.
CALCULATING CALORIE MAINTENANCE LEVEL
You can find many calculators on the web to calculate your daily energy needs, usually based on the well-known Harris and Benedict formula. The problem with this calculation is that you have to apply a much too general add-on. For example: “x 1.55 for people who exercise 3 to 5 times a week and have an average active job”. If you start calculating like this, you get deviations of hundreds of calories. Bodybuilders who engage in lean bulking cannot afford such global estimates.
It is therefore better to calculate only your ‘bare’ maintenance level and manually add the calories from physical activity to that. See our step-by-step plan to that.
STRENGTH TRAINING FOR FAT LOSS?
In bodybuilding, strength training is primarily intended to grow muscle mass. This is in contrast to some forms of metabolic strength training, such as body pump, which target both fat loss and muscle growth (or maintenance).
When you’re cutting, strength training primarily serves to maintain your current muscle mass. After all, with a long-term significant calorie deficit, muscle building is virtually impossible. In doing so, you stick to your training program that you used during bulking as much as possible, because this is the only way you give your body the signal that it is necessary to maintain that muscle mass.
So don’t change your strength training while cutting in order to burn more calories (more repetitions and shorter rest times, for example). Because if your muscles are no longer stimulated at the same intensity, you risk the breakdown of muscle mass that your body then sees as unnecessary. As bodybuilding coach Christian Thibaudeau puts it succinctly:
Don’t lift to lose fat.
To lose fat, follow a calorie-restricted diet, possibly in combination with some cardio. The few hundred calories you burn with strength training should only be seen as a bonus.
Do you still want to incorporate some fat burning into your strength training? Then do some metabolic finishers at the end of your training. At most ‘some’, because your recovery capacity is much more limited than normal, especially during a long cut.
CONCLUSION AND ADVICE
An average 70 kg person probably burns between 100 and 250 kcal during half an hour of strength training. The exact amount depends on the training intensity, the type of exercise, the amount of metabolic stress and the training program (full body or split). After the training you burn another 50-100 kcal by EPOC.
When calculating, take into account the calories you would have burned at rest (1 kcal/kg/hr).