An examination of energy expenditure when squatting for reps
If you’ve squatted for reps you probably know that you’ve just done a cardiovascular workout especially as the weight increases. A ten rep squat at 300lbs would leave me gasping for breath with my heart rate through the roof, I have long femurs so the bar has to travel quite far for me to hit parallel ( exaggerating a little on the gasping but you get the point). Just the other day I completed a pyramid loading squat routine which we’ll examine later in this article.
*Cory confirmed for wearing sunglasses in doors
What you need to know
- Resistance training places demands on the phosphagen, glycolytic, and mitochondrial energy systems (Robergs) and can certainly be used in conjunction with diet interventions to help aid in fat loss and favorable changes in body composition
- Could it also help with cardiovascular function? Escamilla et. al stated that deadlifting for 4 sets of 8 at 175 kg would have the lifter expending 3.5 L *O2/min -1 which is relatively high compared with walking, jogging, and other common actives (Escamilla). You can read more about that here.
A 2007 article by Robergs et. al wanted to examine the energy expenditure of the bench press and the back squat. They used steady state squatting with light weight to predict the actual cost of resistance training at higher intensities.
They had thirty male subjects aged 18-45 years old with a minimum of 1 year weight training experience. One rep maxes were tested, body weight was included. Pilot test had determined that 31-56 % of subjects 1RM (3-25% of 1 RM on the bar) could raises VO2 levels while being light enough to be lifted for 5 minutes. VO2 was measured and indirect calorimetry was performed for the 5 minutes of exercise. Repetitions were set at 20 reps per minutes or 3 seconds per rep.
Indirect calorimetry cannot be used during moderate to high intensity exercise because it doesn’t take into account the phosphagen and glycolytic system (Robergs). That is why light weight for 5 minutes was used.
For the squat, load and distance were able to account for 65.6% of total variance. “Remaining variability could be a result of undetected differences in rate, individual differences in body geometry (ratio of femur length to tibia/fibula length) and or technique differences” (Robergs). Here is the equation that Robergs used. I filled in the bar distance and the load I used for my squat routine.
Y= -1.424 + (.022) (X1)+ (.035)(X2)
X1= load in kg = 275 pounds on the bar + 190 pounds body weight / 2.2 = 211 kg
X2= distance in cm = 49 cm
“Distance was defined as the span between where the load started and where it completed the eccentric portion of the contraction”
Y= -1.424 + (.022)(211kg) + (.035)(49cm)
VO2 = 4.933 (L * min -1)
Escamilla et. al. stated in an article examining energy expenditure that, “ a typical 8 repetition deadlift set takes approximately 30 seconds to complete”. Therefore on a typical 4 sets of 8 deadlift session the athlete would be working for two minutes. They concluded that the VO2 that the lifter was working at for the conventional deadlift was 3.5 LO2 * min which equated to 17.5 calories/minute or 35 calories for the deadlifting session. However, they counted the rest period as part of the equation and calculated the total work time to be 6.5 minutes meaning the athlete burned almost 115 calories.
Let’s take that timing to my squat routine and apply the weight. We’ll examine total time doing work and then factor in rest periods to examine both. We’ll apply deadlift time to squat time since I didn’t have a stop watch going at the time (I think this would be more applicable than the 3 seconds per rep in the squat study by Robergs because we weren’t on a set cadence). Since 4 sets of 8 on a deadlift takes 30 seconds we’ll say each rep took 3.75 seconds. This makes sense as it is generally recommended on the squat to perform a controlled 2-3 second eccentric with an explosive concentric. We’ll say each rep took 3.75 seconds.
We did 9 sets following a pyramid rep scheme that looked like this 2,4,6,8,10,8,6,4,2 meaning we did 50 reps which would equate to 187.5 seconds under the bar or 3.125 minutes of work.
If the VO2 I was working at was 4.933 L *min-1 then I was burning around 25 calories per minute or 78 calories throughout the whole squat session. Now if we also include rest in between sets, let’s say 60 seconds. This is certainly an underrepresentation, we were going rapidly but there were three of us and we changed the weight for each lifter. VO2 didn’t drop back to resting levels within a minute (can someone tell me how long it takes to return to normal? I’m curious) but I also wouldn’t consider myself to be burning a tremendous amount of calories at rest either. So that would equate to 8 minutes of rest and then a total of 11.125 minutes which is around 275 calories burned.
Robergs et. al. did find that their equations predicted values that were higher than previously predicted values. Perhaps because other studies didn’t take into account all energy systems. It would seem that resistance training is a great way to burn calories while maintaining lean body mass. Oxygen consumed is comparable to jogging as well. If a person’s goal is to lose weight and keep muscle they may want to try resistance training with mulitjoint movements such as the squat or deadlift.
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Escamilla RF, Francisco AC, Fleisig GS, Barrentine SW, Welch CM, Kayes AV, Speer KP, and Andrews JR. A three dimensional biomechanical analysis of sumo and conventional style deadlifts. Med Sci Sports Exerc 32: 1265-1275, 2000.
Robergs RA, Gordon T, Reynolds J, and Walker TB. Energy expenditure during bench press and squat exercises. J Strength Cond Res 21: 123-130, 2007.