Exercise- Why exactly do we need it?

We all know that training or exercise of any sort is healthy for us. Medical doctors like to talk a lot about prevention and a big part of prevention will come down to exercise, weight management, and refined food avoidance. It is so important that we have physical activity in schools. We have different kinds of sports. We have soccer and basketball professional leagues for watching in leisure time, even the Olympic Games. We glorify professional athletes as role models for our children. Even our dog gets agitated if he does not receive his daily dose of walking.

In health, community exercising has almost a mythical status as one of the best things you can do for yourself except to avoidance of smoking. In reality, when we look at scientific data diet is the number one killer and most important health intervention. Only after diet, there are other risk factors associated with physical inactivity and bad habits like smoking.

Pushing the belief that physical inactivity is the biggest public health problem of the 21st century is not completely truthful.

Physical inactivity barely makes it in the top ten leading causes of death in the world. Diet is number one and smoking is number two. This doesn’t mean however that exercise is not important. It just means that there are more important lifestyle changes that are affecting the quality of life in a more severe way.

Diet is absolutely number one. The problem we have is that food is an addictive substance and dietary habits cannot be so easily changed. People would just refuse to change their behavior. Exercise is pushed as a holy grail for that one reason. People are addicted to food and exercise unlike dieting can create a lot of profit from professional sports to supplements. There isn’t much money to be made out of carrots.

Promoting a whole food plant-based diet is everything except a money-making machine. Big pharma is a big business and so is the supplement industry. Exercise is a cost-effective and proven way to reduce mortality. Cost-effective means it does not lower the profits of existing businesses and most importantly a way that people can accept.  This doesn’t mean that it is not as important as a preventive measure. In real life, it will provide a substantial benefit. And yes we all should exercise.

By why?

That is the first question we should know. Well, it is not because exercise itself is healthy. It is a stressful, painful experience full of sweat and the possibility of injuries that increases oxidative stress and leads to the creation of free radical DNA damage. There are no animal species in nature that likes to “exercise”. There is nothing romantic in hunting or foraging for food. It is an existential necessity that is forced. When we exercise what we essentially are doing is that we are simulating an environment in which our ancestors have evolved. It is a form of self-inflicted pain. Pain that just by itself is not healthy and will create DNA damage due to the excessive production of free radicals due to increased oxygen consumption.

If free radicals damage DNA and exercise leads to the creation of free radicals then how can it be that physical activity can be healthy?

It is because our hominin ancestors lived by foraging. That created evolutionary adaptations in our biology.  Physical activity was an essential component of their survival. You do not forage, you do not find food, and you die. It is that simple. The only reason exercise is healthy is because in a million years of evolution our body adapted to it. Our body expects it as a normal part of life.

When we do not exercise we are out of balance with our physiology, and when we do, we give our bodies what they are expecting. When we go to the gym or do any other exercise like running on the treadmill, what we are doing is that we are simulating the conditions in the habitat of our hominin ancestors.

When we look for scientific research about exercise, what will we find? Does exercise matter or it is just something to help us lose weight more rapidly? What we find is that individuals with low levels of physical activity are at higher risk of many different kinds of diseases like heart disease, cancer, Alzheimer’s disease, and also early death by any cause. Long before that, inactivity increase lower-back pain worsens arthritis symptoms and leads to anxiety. Exercise can help with lowering the risk of early death, high blood pressure, stroke, coronary heart disease, adverse blood lipid profile, type 2 diabetes, metabolic syndrome, colon cancer, breast cancer, depression, and can increase cognitive and mental health, sleep quality, immune system function and longevity.

There are a couple of main benefits of physical activity. The first and main one will be its effects on the cardiovascular system. You are probably doing to do some “cardio” in the gym.

When we exercise, the heart starts to contract forcefully and frequently. That will increase blood flow through the arteries and allow our muscles to use more oxygen. An increase in blood flow will cause subtle changes in the autonomic nervous system, which controls the contraction and relaxation of these vessels. This adaptation leads to lowering blood pressure, a more variable heart rate meaning the ability of the heart to slow down or increase contractions when needed and a lower resting heart rate overall which means increased efficacy of the cardiovascular system with fewer beats to pump blood through the body. All aspects have an impact on lowering cardiovascular disease.

Exercise also lowers inflammation associated with the cardiovascular system. Exercise in research was able to cause around a 30 percent dip in C-reactive protein levels, a marker of inflammation. Thirty percent drop is about the same drop that statin (the cholesterol drug) is able to cause. It beefs up the body’s immune system and wards off cancer and other diseases.

One of the main benefits will also be an increase in insulin sensitivity. When someone runs, muscle contractions will increase the production of adenosine monophosphate-activated protein kinase (AMPK). This is an enzyme that promotes the breakdown of fats that can interfere with the cell’s glucose transporters. AMPK can help in preventing type 2 diabetes.

Research in rats shows that physical exercise boosts BDNF (brain-derived neurotrophic factor). BDNF is an essential factor in learning and memory. BDNF helps rats to remember how to navigate their way through mazes, and similar activity can be assumed in humans.

Exercise will help to maintain bone mass and will reduce the risk of osteoporosis. Bones become stronger when forced to adapt to bear more weight than usual.

The Department of Health and Human Services (HHS) monitors this kind of research and releases periodically its Physical Activity Guidelines for Americans. Recommendations are that:

“Adults between the ages of 18 and 64 exercise moderately (walking) for at least two hours and 30 minutes or vigorously (running, swimming, or cycling ten mph or faster) for at least an hour and 15 minutes weekly”.

 That is about 11 minutes of running a day on the treadmill. For people who do not understand how to read this kind of release, the keyword is for at least. The more is better. They are recommending what they think may be achievable. When we look at their charts of the correlation between exercise and premature death all we can see is just a steady linear drop. 

If we exercise 180 minutes a week, we will have a 27% lower risk but if we exercise 420 minutes a week will have a 38.5% lower risk, and this kind of correlation is found in all studies and systematic reviews and meta-analyses of cohort studies. In one study (Mok et al., 2019) they reviewed 22 studies that met inclusion criteria. A study containing 977,925 individuals (334,738 men and 643,187 women) and found that 2.5h/week (equivalent to 30min daily for 5 days a week) compared with no activity was correlated with a decrease in mortality risk of 19%, while 7h/week of moderate activity compared with no activity reduced the mortality risk by 24%.

The conclusion was that:

“Being physically active reduces the risk of all-cause mortality.”

Going from no activity to a small amount was found to provide the most significant amount of benefit.

However, that does not mean that if we are active that there is no additional benefit. Even at high levels of activity benefits still, accrue from the additional activity. The more and the longer the exercise, the more benefits.

References:

1. Mok, A., Khaw, K., Luben, R., Wareham, N. J., & Brage, S. (2019). Physical activity trajectories and mortality: population based cohort study. BMJ, l2323. https://doi.org/10.1136/bmj.l2323
2. Arem, H., Moore, S. C., Patel, A., Hartge, P., Berrington de Gonzalez, A., Visvanathan, K., Campbell, P. T., Freedman, M., Weiderpass, E., Adami, H. O., Linet, M. S., Lee, I. M., & Matthews, C. E. (2015). Leisure time physical activity and mortality: a detailed pooled analysis of the dose-response relationship. JAMA internal medicine, 175(6), 959–967. https://doi.org/10.1001/jamainternmed.2015.0533
3. Woodcock, J., Franco, O. H., Orsini, N., & Roberts, I. (2011). Non-vigorous physical activity and all-cause mortality: Systematic review and meta-analysis of cohort studies. International Journal of Epidemiology, 40(1), 121-138. https://doi.org/10.1093/ije/dyq104