2 Acronyms To Know (Regarding Weght Training)
Oct 5, 2016
Upon entering into our FT location, the first thing you will see is our cardio studio. Consisting of a recumbent bike, a treadmill, and an elliptical machine, this portion of the studio is usually reserved for our clients’ warm-up period; rarely do these machines see any use in the session itself. Most of our programs rely on resistance training, and for good reason. Resistance training is a very versatile modality, capable of working muscular endurance, strength, and power through a wide range of equipment choices for a variety of health benefits.
One of the most common fitness goals we get here at FT (and trainers at other gyms) is weight loss. And what does everyone dread about exercising for weight loss? It’s the running, or biking, or long walking etc. that comprise the category of traditional cardio exercise. The good news is resistance training can be tailored for weight loss, though the way the body responds to resistance training is different than how it responds to traditional cardio. Resistance training takes a more roundabout way to accomplish this task through alterations it can make to both your short term, and long term metabolism. That dynamic can be understood through two major processes, one that affects short-term metabolism, and one that affects long-term metabolism. On the surface, they may sound complicated, but that’s why we have acronyms to make them simpler.
Short Term Metabolism: EPOC
After exercise, there is a period of time when your body is in full-blown recover/replenish mode, rebuilding muscle tissue that has become broken down from repetitive use, and refilling stores of energy molecules. Like most chemical processes in the body, the reactions involved with rebuilding and refilling require oxygen. So what the body does in order to make sure that tissues get the oxygen supply they need to accomplish these tasks, it keeps oxygen consumption elevated above resting levels for a period of time after stopping exercise. This function is termed excess post-exercise oxygen consumption, or EPOC. This is an important concept because when oxygen consumption is elevated, that means metabolism is elevated and thus energy is being burned. Burned energy, equals burned calories.
The reactions involved in rebuilding and refilling are largely anabolic in nature, which means they use energy to take smaller molecules and piece them together to make larger ones. One such example on the refilling side is glycogen, a molecule made up by basically taking smaller free glucose (sugar) molecules in the body and coupling them into a larger, more energy-abundant unit. On the rebuilding side, myosin, a muscle protein, is constructed by linking six smaller chains of protein together. Oxygen is a driving factor in both of these reactions, so what we see in these cases is that oxygen consumption and metabolism are highly correlated. This in turn allows us to know that metabolism after resistance training remains elevated up to 24 hours after the completion of exercise. So for 24 hours after training, you burn more calories than you normally would if you hadn’t exercised the day before. This is largely thanks to the rebuilding half of the recovery process (aka the increase in protein synthesis needed to rebuild muscle tissue).
Now during the process of the refilling half, the body is still relying on blood glucose and free fatty acids in the blood stream. However, during the recovery process, it tends to rely more on free fatty acids than blood glucose. Fatty acids can be used to manufacture a wide range of molecules in the body, including glucose and glycogen. The reason why goes back to EPOC. When there is a high supply of oxygen for the body to use-which is what EPOC is designed to create-your body tends to want to burn more free fatty acids than blood glucose. As a result, your body will break down fat stores around the body to release more of the smaller free fatty acid molecules into the blood stream for utilization. So while you may not be burning as much fat during resistance training as opposed to cardio training, you certainly start burning it after, and there is evidence that compared to endurance training, resistance training induces a greater EPOC phase that also seems to last longer than the EPOC phase for endurance training.
Long Term Metabolism: REE
As long as you are breathing, you’re burning calories. You’re burning calories right now while you’re sitting and reading this. Granted the rate at which you burn these calories is not up at the rate you burn them at exercise. The rate at which you burn calories during at rest, like when you’re sitting, is known as your resting energy expenditure (REE). Your REE accounts for somewhere in the neighborhood of 70% of the total calories a normal person will burn in a day, and what research has found is that REE is largely correlated with an individual’s fat-free mass. Fat-free mass includes muscle, bone tissue, organs etc. and these comprise the most active tissue types in the body. So as a result, the energy expenditure of these tissues is the largest influencing factor on REE.
Now the organ tissues tend to use the most energy (approximately 468 calories per kilogram of body weight per day), than muscles do (approximately 15 calories per kilogram of body weight per day), though these numbers can vary widely from individual to individual. There is not much we can do with the expenditure of the organs, but what about the expenditure in the muscles? Higher intensity resistance training has been shown to increase muscle mass by as much as one pound per month, which in turn can increase your REE by up to 7%. This means that, for example, if someone’s REE was say 1600 calories a day, with resistance training the possibility exists to elevate that person’s REE to over 1700 calories in the long term. This makes sense, given the increase in energy-hungry fat-free mass, means more calories are being burned. Over months and years, those extra calories add up. Also of note, REE does not include the calories burned during any kind of physical activity, like the calories burned while participating in a resistance training program. So while cardio and endurance training are the training modes most touted for weight loss, when you combine the short-term energy expended during training, and immediately after training, as well as the potential long term adaptations of REE together, it’s clear to see resistance training has a place in this realm too.
Paoli, A., Moro, T., & Bianco, A. (2015). Lift weights to fight overweight. Clinical physiology and functional imaging, 35(1), 1-6.
Westcott, W. L. (2016). Strength training for those who need it most. ACSM's Health & Fitness Journal, 20(5), 23-28.