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How Many Calories Are Burned Lifting 280 Pounds?

Jun 22, 2011 | By Thomas Walker
How Many Calories Are Burned Lifting 280 Pounds?
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Exercise scientists hear some variation of the above question quite often. But the answer to it is not simple. Unlike with most forms of endurance training, figuring the caloric cost of resistance training can be difficult. Despite that and the fact that resistance training has traditionally been practiced for increasing strength, it has become increasingly common for people to use resistance training in the pursuit of improving body composition. Scientific evidence has supported such a practice with multiple studies reporting that resistance training can promote more lean body mass as well as less body fat.

Resistance Training Improves Body Composition

Traditionally, doctors and scientists have recommended aerobic exercise for improving body composition. However, research led by South Korean exercise scientist S.K. Park found that subcutaneous fat and visceral fat levels were decreased significantly more in a resistance training plus aerobics training group than in an aerobics only group. Parallel research out of Southern Illinois University found that after 10 weeks of endurance training alone or endurance training with resistance training, all subjects showed a significant reduction in waist-to-hip ratio but only the resistance training group showed a reduction in total body fat. Accordingly, studies investigating the body composition of male Olympic weightlifters and powerlifters have consistently reported that their subjects' body fat percentages compared favorably to those of average college-aged men. Likewise, a study out of Old Dominion University, found that 14 weeks of resistance training resulted in a significantly lower body fat percentage in young women.

Bioenergetics of Resistance Training: A Difficult Equation

Unlike with traditional endurance or aerobic exercise, it is very difficult to accurately estimate how many calories you burn while lifting weights. The reason for that is that while endurance training uses energy produced almost exclusively by oxidative metabolism, resistance training places high energy demands on the oxidative system as well as the non-oxidative glycolytic and phosphagen energy systems. Scientists can measure the energy you spend oxidatively by collecting your expired breath and measuring it for volume and gas content, a process called indirect calorimetry. But energy created by the other two systems cannot be measured in this relatively simple fashion and so has generally been either ignored or roughly estimated by exercise scientists.

Bioenergetics of Resistance Training: Individual Variation

The other issue which makes calculating caloric expenditures difficult is the multitude of variations in how you lift that weight. The more muscle mass used, the higher the number of calories burned, so squats generally burn more calories than overhead presses. The distance the weight is moved makes a difference so someone with long limbs has to do a little more work to bench or squat a weight than someone with shorter limbs. Speed of movement and relative intensity also make a difference. A 2007 study by Anderson University reported that explosive contractions and moderate intensity induced a greater energy expenditure than using slow contractions or high intensity. Finally, free weight lifting generally involves greater muscle mass and therefore burns more calories than machine-based resistance training.

Best Estimates for Resistance Training Energy Expenditure

Despite all this potential confusion, several scientists have devised ways to estimate energy expenditure during resistance training. Work produced in 2006 at the University of New Mexico detailed specific formulas for calculating calories burned while squatting and bench pressing. While those formulas are likely accurate, they are a bit cumbersome for the layman. To give you a slightly less accurate but much easier to use method, the formulas indicated that the cost of the bench press and squat --- large muscle mass exercises --- equals about 12 kcals/min at light to moderate intensities and 18 kcal/min at moderately heavy intensities and likely more than 20 kcal/min at maximum intensities. For comparison's sake, a 176-lb. person running on a treadmill at 6.5 mph and a 2 percent grade burns about 16.5 kcal/min. Those estimates make a good case for the body composition altering potential of resistance training and using them should allow you to get a fairly close estimate of the calories you burn at the gym.

References

Article reviewed by Contributing Writer Last updated on: Jun 22, 2011

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