By: Heather Roberts, Free Press Staff
On the Gorham campus, a Human Performance Lab has students hooked up to metabolic carts, a device used to measure oxygen consumed during exercise, to estimate how many calories they’ve burned. The goal of this research, according to Professor Christopher Scott of the Department of Exercise, Health and Sports Sciences, is to estimate energy expenditure before, during and after exercise.
If you’ve ever wondered how many calories you can burn while participating in a particular activity, such as bench pressing, bicycling or running, Scott has observed in his research that short, intense and intermittent exercise, followed by a recovery period, can help an individual burn the most fat.
This research, performed by lab students for science classes, attempts to measure the amount of energy produced during anaerobic exercise. Strength, speed and power tend to distinguish anaerobic exercise from aerobic.
Aerobic exercise is the type of physical activity that only uses oxygen. Anaerobic exercise is different from aerobic exercise because this type of physical activity makes the muscles clamp down on blood vessels, decreasing oxygen.
Due to the fact that muscles get less oxygen during anaerobic exercise, to make energy muscles resort to producing lactic acid from sugar. To measure the amount of energy produced during anaerobic exercise, students measure lactic acid in the blood.
As well as taking measurements of aerobic and anaerobic physical activity, students record their subjects’ oxygen uptake for the recovery period, or the ten or fifteen minutes following exercises where the body brings itself back to its state before exercise.
After taking the measurement of aerobic, anaerobic and recovery of a physical activity or activities, lab students input the data into a cost per task formula, where the cost is the volume of oxygen consumed and the task is a physical activity, which can include walking, running or weight lifting. They then graph the results overall to see the total energy cost.
Through this research analysis, Scott recommended an estimated seven seconds of intense exercise such as sprinting, weight-lifting or vigorous cycling, followed by three to four minutes of active, multiple recovery periods that include activity such as walking or light cycling. He explained that, for every liter of oxygen consumed, five calories are burned.
“[During] the recovery period, we’re bringing the body back to what we call homeostasis [stable equilibrium],” he said “So back toward resting metabolic rate and that takes energy.”
Everyone is different, so rigorous intermittent exercise with long pauses may not always be the best option. To lose weight, a twenty-minute walk might be better. Scott warned that one must be careful about how they use intensity in a workout, saying that perceived exertion, or what you think of as intensity, does not dictate what the energy costs are.
According to Scott, since rigorous physical activities, such as weight lifting, tend to become anaerobic exercises with long recovery periods, the cost per task formula is better at calculating total energy expended than the well-known cost per minute formula. On the other hand, Scott has found that, after a while, exercise and recovery periods plateau in calorie and fat consumption.
“If you keep exercising, you’re actually becoming more efficient as time goes on,” he said, adding that six percent of sugar breakdown is anaerobic while aerobic exercise accounts for the other 94 percent.
According to Scott, to explore the recovery phase further, additional research such as a student-led longitudinal study may help. For now, undergrad students perform short experiments on health and fitness for their Thinking Matters presentations.
The most recent results show that an interval exercise is best to burn both calorie and fat. “Really intense bouts – very brief and then coupled with some sort of active recovery,” Scott said, “You can’t get any more expensive than that.”