How to Calculate Calorie Burn During Strength Training.

How to Calculate Calorie Burn During Strength Training. You will only be able to get approximate values.

During cardio training, a consistently elevated heart rate allows you to easily calculate the calories burned. With strength training, things are more complicated, since they alternate periods of work and rest between sets.

When you do a set of any exercise, your heart rate increases , and when you rest, it decreases. But even then, you burn more calories than you would at rest, due to oxygen debt—the excess O₂ consumed after intense exercise.

Moreover, you will continue to use more energy after you leave the gym until your body returns to a calm state. All this complicates the calculations, so the only way to accurately say how much you will use is with a gas analyzer – a special mask that is put on your face during training, then the amount of oxygen consumed is determined and calories are counted.

At the same time, based on research data, we can roughly imagine how much energy strength training consumes.

How Many Calories Does Strength Training Burn

In one study, scientists tested how many calories men and women would burn during strength training. Participants performed eight strength exercises, each with one set of 15 repetitions.

The weights were chosen so that a person could perform the exercise exactly 15 times.
Scientists calculated energy expenditure and found that men spent an average of 5.6 kcal per minute during exercise, while women spent 3.4 kcal per minute. This is not surprising, given that the average weight of women was 62 kg, while men weighed 90 kg, and the latter had significantly more muscle mass.

In another experiment, women burned about 155 calories during a full workout of 10 exercises, each performed in three sets of 10 reps with a minute of rest. And then an additional 31 calories during recovery due to oxygen debt. The workout lasted 45 minutes, so we can conclude that they again burned about 3.4 calories per minute. The average age of the women was 29, the average weight was 59 kg.

During strength training, women burn about 3.4 kcal per minute, while men burn about 5–6 kcal per minute.

It doesn’t really matter whether you work with heavy weights for a small number of repetitions or choose lighter weights and do 10-15 repetitions with them. At least if you perform the exercises until your muscles become significantly fatigued .

In one study, scientists decided to calculate how much energy is spent on strength training of different intensity. Young trained men performed classic strength exercises: bench press, squats, pull-ups on the block and others, and scientists used a gas analyzer to find out how many calories they spent.

The study authors tested three training regimens:

1. With low intensity – 2 sets of 15 reps with 60% of the one-rep max . That is, from the weight with which you can do the exercise only once.
2. At medium intensity – 3 sets of 10 reps at 75% of 1RM.
3. High intensity – 6 sets of 5 reps at 90% of 1RM.

In all modes, men rested for 2 minutes between sets.
The results showed that high-intensity strength training helped participants burn about 610 kcal, medium-intensity training burned 360 kcal, and low-intensity training burned 283 kcal.

But this difference was due solely to the duration of the sessions. Low-intensity training lasted only 44 minutes, medium-intensity training burned 61 minutes, and high-intensity training burned 116 minutes.

It turns out that during low-intensity strength training, men spent about 6.4 kcal/min, with medium intensity – 5.9 kcal/min, and with high intensity – 5.2 kcal/min. A greater number of repetitions with a small weight turned out to be more energy-consuming than short approaches with heavy equipment. Although if people had been training for the same amount of time, the difference in energy expenditure would still have been small – only about 50 kcal.

On the other hand, the researchers did not measure oxygen debt in this study. There is some evidence to suggest that after heavy resistance exercise, people consume more oxygen and burn more calories at rest than after moderate-intensity exercise. However, this has not been well studied.

How to Calculate How Many Calories You Burned During Strength Training

You can roughly calculate the number of calories burned by multiplying your workout time by the approximate energy expenditure for women and men – 3.4 kcal/min and 5.6 kcal/min, respectively.

But here we must take into account that the studies where these figures were obtained involved young people with a low percentage of fat . Men and women with a different body composition may expend less energy.

Energy expenditure during training may vary depending on the following factors.

1. Rest time between sets. In studies, people rested between sets and repetitions for a fixed 60-120 seconds. If you spend a lot of time talking to other exercisers or forgetting yourself scrolling through your social media feed, your workout may burn far fewer calories. And vice versa: if you reduce the amount of rest, your energy expenditure will increase.
2. Body composition. Since muscle uses energy and fat is its source, body composition directly affects calorie expenditure. The more muscle a person has, the more energy they use both at rest and during exercise .
3. Fitness level. The longer you do an activity, the fewer calories you burn. This happens because when learning new skills, the body strains much more than it needs to. Over time, the body gets used to the movement and finds the most efficient way to perform it, so energy expenditure decreases.

Of course, it is difficult to predict how many calories exactly you need to subtract or add if, for example, you rest not for 2 minutes, but for 5. Or if you have a high percentage of fat mass and very little muscle. It remains to focus on the general values and keep in mind that your energy expenditure may be slightly more or less than stated.
You can also try using calorie calculators, such as those at Verywell Fit or ACE Fitness . They break weight training into just two intensity categories: moderate and heavy. These tools can help you calculate the approximate energy expenditure of your strength training based on your body weight and the length of your workout, but don’t expect particularly accurate results.

We tried entering the data of men from the study with three strength training modes and got values that are not even close to those stated in the results of the experiment. According to the calculations of the calculators, a man weighing 83 kg should burn 186-192 kcal in 44 minutes of average strength training, and if the training was hard – 373-383 kcal. In the study, the men burned an average of 283 kcal. Thus, the calculators are off by about 100 kcal in either direction.

But with women this tool works more or less accurately. If you check the data from the experiments above, the calculator is off by only 10 kcal.