We’ve all heard that physical activity is important…
Just how important is moving?
Specifically, how important is it?
The general idea for why all of healthcare focuses so much on physical activity because the more active a person is, the more resilient the body will become. This doesn’t simply apply to the physical body, this applies to, everything. Mental stress is relieved from physical activity, blood flow increases to areas that require healing, muscles and bones become resilient to damage, and body composition can more easily be maintained. All of these effects come from maintaining a moderate level of activity.
So what is meant by the term “physical activity”? Ideally, any kind of activity that causes you to increase your rate of breathing, increase your heart rate and physically tires you out. This can be sport related, physical labor (landscaping, home remodeling, etc), as well as any kind of activity above and beyond your standard requirements for life. For instance, if you are a stay at home parent, and typically do 5,000 steps a day while maintaining the house and doing any kind of child care, an “increase in physical activity” would be above and beyond the 5,000 steps you’re already doing. It’s very important for the body (both mind and physical body) to have self-driven activity that is physically exhausting.
If activity is important, how much activity is important?
There is consistent research posted about the importance of maintaining a regular level of cardiovascular activity (exercise). The particular article referenced here, cited exercise in terms of a “MET” or metabolic equivalent. So, what is a “MET”? 1 MET, is approximately 1000 Calories per week of activity.
Slow walking (2 mph) for 20 minutes burns around 86 Calories.
Fast walk (4mph) for 20 minutes burns approximately 160 Calories.
In this case, 1 MET of exercise would be walking 4 mph for 20 minutes, 7 days a week. This would account for approximately 1120 Calories burned in one week.
This term is used to standardize the level of calories burned for all exercises, to better compare and research exercises effects on overall health.
The “gold standard” of measuring levels of activity, is to assess how much oxygen the body is using. This is the “gold standard” because oxygen is the fuel that drives our body’s ability to function. In high tech research facilities, athletes can be connected to machines that can monitor how much oxygen goes in and out of the body during exercise. By comparing the amounts, you can determine how many calories were burned, via complicated math. This measurement is the BEST, but it is also very time consuming and requires a lot of expensive equipment. By calculating METs, we can have a “good enough” approximation, without all the expensive work required to measure VO2 Max.
(VO2 Max testing shown here)
In terms of importance of health, 2-3 METs per week of activity was correlated with 2-5x decrease in heart disease AND 2-5x decrease in all-cause mortality as compared to 0 MET (sedentary) living. This means not only are your risk of heart related conditions decreases 200-500%, but it also decreases your risk of any kind of serious health related problem.
In easier terms, walking at a fast pace, for an hour, every day, has the potential for lowering your risk of health-related death by 500%!
This benefit is further increased for women who, if they maintain a level of physical activity, every MET of activity adds another 17% decrease in mortality!
You read that correctly. For week that engage in a fast walk for only an hour a day, there is a 5-fold decrease in your risk of health-related death.
While I reference walking, this qualifies for any level of physical activity, as long as it is above and beyond 1,000 Calories of activity. Any tiring exercise that raises the heart rate and is maintained for a length of time, will be beneficial to one’s health. Increased activity levels have shown to increase immune resistance, decrease body weight and increase mood promoting hormones. Keep in mind, these benefits can be gained from as little as 1-2 METs of activity.
The largest benefit and health protection comes in at the 8-10 MET level. While this level seems remarkably high to most people, this is the level at which the most health benefit is obtained. MET levels less than 5 have a higher risk of CVD and all-cause mortality. However, the largest increase in benefit comes between the lowest level, compared to the 2nd lowest level. Increasing your activity from 0 extra Calories burned, to burning 1-2 thousand Calories per week increases your potential health significantly from a moderately poor outlook, to a mildly good outlook.
Why does activity have to be tiring?
There’s two major reasons for regularly physically exhausting one’s self. The first and foremost, the muscle of the body requires constant use. We have muscle, we can’t just neglect it. The more muscular definition is neglected, the more difficulty the body has to operate. As jobs become more and more sedentary in the US, movement needs to be increased. As muscles are forced to exert more and more force, the tissues around them are forced to contract and slide. This increased activity prevents the muscles from adhering together. This keeps the muscles loose and pliable as well as allows the joint to move freely when needed.
The second reason is the related to the how body fat exists in the body. When we increase our energy levels, the cells that produce energy (called mitochondria) increase in activity. If this new higher energy demand is maintained, the body is required to produce more mitochondria, thus making the body more energy on a regular basis. (You’ll feel less tired from the same level of activity) The main benefit here, is related to how mitochondria produce energy. We discussed body fat once before.
See all those -C-‘s in the middle? Those are carbon atoms. Once the body starts breaking these large fat molecules into smaller pieces, those carbon molecules have to go somewhere. The place they go, is out through the lungs via CO2. 90% of body weight lost, is lost as CO2. The rest of the Hs and Os are combined and used as water within the body.
Need further proof?
This big complicated picture is how the human body produces energy from sugar. Body fat is converted to a similar form via the process known as gluconeogenesis, and processed accordingly. See all the H2O and CO2?
H2O is used to further break down other fat molecules via a process known as hydrolysis, and CO2 is created every time a carbon molecule is broken from the main molecule.
Source: Ross, R., Blair, S. N., Arena, R., Church, T. S., Després, J., Franklin, B. A., . . . Wisløff, U. (2016). Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association. Circulation, 134(24). doi:10.1161/cir.0000000000000461