Almost everyone knows that physical activity is beneficial, but what effect on health does it really have? Throughout the history of mankind we have been mostly nomadic. Our ancestors walked/ran everywhere, spent a lot of time picking berries and fruits, and before horses really had no other choice but to walk. Once we discovered agriculture we settled down and were not forced to be as active as we previously were since we could live in one area without having to move for food.
Fast forward to today. Most of us work 8-9 hours a day and sit down almost the entire time. We then get in our car and drive home where we eat dinner, watch television and sit around some more. Those who are active may play a sport, participate in gym classes or go for a run. But can a thirty minute run really make up for the other 90% of the day where we just sit around? I just find it amusing that I run 2-3 miles most days and consider this ample physical activity while I sit around for the rest of the day. This is a gigantic deviation from how our ancestors lived up until a few thousand years ago.
Before I get into the health benefits of physical activity I must say a few things. The first thing is that those who are physically active tend to have lower rates of mental illness and are more likely to eat healthier than their inactive counterparts. When we exercise we tend to feel good and this carries over into wanting to eat healthy too. Those who chose to engage in physical activity may be more motivated, disciplined and concerned with maintaining a healthy body weight than inactive people.
These reasons make it very hard to point to exercise as the reason for lower rates of heart disease, diabetes, cancer, etc. where diet, mental health and motivation likely play a large role as well. Those who exercise may also sleep better/longer. With that out of the way, there are many interesting studies to talk about! Just keep an open mind and remember that there are other variables besides the physical activity that likely influence the health benefits.
The effect of exercise on our endurance
The more we exercise, the better our body is able to utilize oxygen and our endurance increases (1). Exercise can also benefit our body even when at rest; exercise training decreases myocardial oxygen demand and increases cardiovascular functional capacity in healthy as well as those with cardiovascular disease (1). We need to exercise regularly to maintain these health benefits.
The relation between physical activity and cognitive function (including Alzheimer’s disease)
A 2008 study measured the impact physical activity had on the cognitive function in those over 50 years old with slight memory problems but not dementia (2). Those in the physical activity group had improvements in a cognitive test compared to the non physical activity group which were comparable to those seen with the use of donepezil (a drug used to treat dementia) (2). Although the trial only lasted 6 months, the cognitive benefits of those in the physical activity group persisted for at least another 12 months after the study ended. The most interesting part of this study was the fact that all of the participants were randomly put into the exercise group or non exercise group so the two groups should not have differed in motivation or lifestyle.
Physical activity and mental illness
Although I do not agree with the theory, I will talk about the results anyway. It was found that physical activity was associated with a significantly decreased likelihood of having Generalized Anxiety Disorder, Major depression, panic attacks and specific phobias (3). Knowing many people with mental illness and working in a group home for those with mental illness I do not believe that physical activity causes a decrease in mental illness. I do believe that mental illness causes a decrease in physical activity though. Genetics is likely to blame for most cases of major depression and anxiety disorders. Most people with these disorders do not care about physical activity or if they do they are too depressed and or anxious to actually go out and be active. Exercise may slightly help anxiety through its effects on hormones and neurotransmitters, but outside of this I believe exercise has little long term benefit in those with serious mental disorders. I am not saying exercise is useless in these individuals; of course exercise can still benefit their overall health! Giving them motivation to exercise is another story however.
Health benefits in Older Men
In England men aged 40-59 were recruited in a study and followed up in 12-14 years to see if there was a relationship between physical activity and all cause mortality and major coronary heart disease events (4). The study found that light exercising and walking was enough to reduce the risk of cardiovascular events in these men (rigorous exercise was not necessary). They found that the greatest health benefit was from sustained moderate exercise. A key finding was that physical activity must be regular to offer health benefits so just walking on the weekend may not be enough to receive the full health benefits. It would be better to walk for a shorter period but more days of the week. The study’s conclusion was that light physical activity reduces mortality and heart attacks in older men with and without diagnosed cardiovascular disease (4).
However, a 2000 study found that light activities did not reduce mortality rates, moderate activity slightly reduced mortality rates and vigorous activity clearly reduced mortality rates (5). The participants in this study were men of similar age to the study in England. More studies need to be completed to find out how the intensity of activity affects mortality rates.
Fit versus unfit men
A more encompassing study measured the relation of physical activity to health in men aged 20-82 years of age (6). Each participant was given two examinations, 5 years apart. It was found that the highest all cause death rates were found in men who were unfit at both exams and the lowest rates were found in those who were fit at both exams. Men who were initially unfit at first exam and fit at the second exam had reduction in mortality risk of 44% compared to those who remained unfit at both exams. Unlike most of the other studies I have mentioned, this study looked at physical fitness which was defined as exercise test tolerance to a treadmill protocol as opposed to taking physical activity into account. Even so, physical fitness is at least partially reflective of physical activity; those who consistently engage in physical activity are more likely to be fit than sedentary men, so this study overlaps with the other studies I have talked about.
Physical fitness and Metabolic Syndrome
Metabolic syndrome is when someone has certain risk factors that increase their risk for heart disease and diabetes such as: a large waist, high blood pressure, high blood sugar levels and high triglyceride levels. It is most common in older adults. Cardio respiratory fitness was found to offer protection against all cause mortality and cardiovascular disease mortality in healthy men and men with metabolic syndrome (7). This shows that even men with metabolic syndrome can benefit from improved physical fitness.
Increase your physical activity by using a pedometer!
A meta analysis looking at studies which assigned subjects to use a pedometer as compared to the control subjects not using one found that those using pedometers increased their physical activity by more than 2491 steps per day compared to the control subjects (8). This turns out to be an additional mile of walking per day (2000-2500 steps in a mile). Having a pedometer on you throughout the day serves as a constant reminder to increase your physical activity. Being conscious of how much you are walking may make you take more interest in walking more each day.
The study found that setting walking goals played a significant part of pedometer users increasing their daily walking amount over their baseline compared to pedometer users without step goals who did not increase their physical activity (8). Setting goals and constantly trying to improve the amount you walk each day can have significant positive effects on overall health.
Numerous health benefits from physical activity
The health benefits of physical activity are too many to go into detail for each. I highlighted just a few benefits of physical activity, but even more benefits include: help you lose and keep off weight, reduce your risk of stroke, lower your blood pressure, improve cholesterol levels, reduce your risk of diabetes, can reduce your risk of getting colon and breast cancer, increase life expectancy, strengthen bones and improve blood glucose control.
\Those at risk from intense physical activity
The following groups of people should start slow or avoid intense physical activity all together: those with uncontrolled diabetes, those with uncontrolled high blood pressure, uncontrolled seizure disorders, and heart failure. It is recommended that blood pressure and diabetes be under control before thinking about engaging in intense physical activity. These conditions increase risk of heart attack and sudden death from intense exercise. If you are older or have certain medical condition speak with your physician before beginning physical activity.
How much physical activity is necessary?
Aim for 2 hours and 30 minutes of moderate intensity aerobic activity a week. That’s 150 minutes a week and there are 7 days in a week so that is about 20 minutes a day. Of course, the more the better. Brisk walking is considered moderate intensity.
I personally like to keep my exercise interesting by switching between long distance, short distance and using the bike and elliptical when my legs are sore. When I run distance I do not time myself and usually listen to an audio book as I run. When I run short distance I usually use a treadmill. Unfortunately treadmill running does not help my outside running much. I find walking extremely boring and prefer to get my heart rate high so I really never walk. Walking is great if you like walking or are unable to run. If you have bad knees your best bet would be riding a bike, using an elliptical machine or swimming. These are exercises that have the least impact on your legs.
I think it is well known that physical activity can bring amazing health benefits. I just wanted to highlight a few in this article. I want to stress that physical activity is NOT a replacement for a poor diet. Just look at those who are extremely physically fit: athletes, competitive runners, bodybuilders, etc. I am willing to bet that these people have lower rates of heart disease and mortality than the average sedentary person but even athletes eventually get cancer and heart disease. Physical fitness most likely will not prevent cancer, prevent heart disease or reverse heart disease. While athletes look fantastic on the outside, what goes on inside our body is what counts.
Someone with an excellent diet who is a healthy weight will likely outlive someone in fantastic shape but with a poor diet. Diet is the foundation for health. Sure, physical activity plays a large role, but diet is the most important factor. Many people are under the illusion that as long as they maintain a healthy weight and remain active they can slack on eating healthy. The only proven lifestyle change proven to prevent and reverse certain cancers and heart disease is a diet full of plant foods and low in animal products.
Physical activity has benefits that extend beyond disease prevention, including feeling better because of neurotransmitter release, feeling more positive and getting a better sleep so I absolutely recommend physical activity at least five days a week. I try to jog/run five days a week and recently starting timing myself and setting goals for my two mile and three mile times. Setting goals with physical fitness makes it more interesting and will help keep you motivated. I have already shown how setting goals and using a pedometer helped subjects walk one mile more a day than those without fitness goals.
- Fletcher, G. F., Balady, G., Blair, S. N., Blumenthal, J., Caspersen, C., Chaitman, B., … & Pollock, M. L. (1996). Statement on exercise: Benefits and recommendations for physical activity programs for all Americans a statement for health professionals by the committee on exercise and cardiac rehabilitation of the council on clinical cardiology, American heart association. Circulation, 94(4), 857-862.
- Lautenschlager, N. T., Cox, K. L., Flicker, L., Foster, J. K., van Bockxmeer, F. M., Xiao, J., … & Almeida, O. P. (2008). Effect of physical activity on cognitive function in older adults at risk for Alzheimer disease: a randomized trial. Jama, 300(9), 1027-1037.
- Goodwin, R. D. (2003). Association between physical activity and mental disorders among adults in the United States. Preventive medicine, 36(6), 698-703.
- Wannamethee, S. G., Shaper, A. G., & Walker, M. (1998). Changes in physical activity, mortality, and incidence of coronary heart disease in older men. The Lancet, 351(9116), 1603-1608.
- Sesso, H. D., Paffenbarger, R. S., & Lee, I. M. (2000). Physical activity and coronary heart disease in men the Harvard Alumni Health Study. Circulation, 102(9), 975-980.
- Blair, S. N., Kohl, H. W., Barlow, C. E., Paffenbarger, R. S., Gibbons, L. W., & Macera, C. A. (1995). Changes in physical fitness and all-cause mortality: a prospective study of healthy and unhealthy men. Jama, 273(14), 1093-1098.
- Katzmarzyk, P. T., Church, T. S., & Blair, S. N. (2004). Cardiorespiratory fitness attenuates the effects of the metabolic syndrome on all-cause and cardiovascular disease mortality in men. Archives of Internal Medicine, 164(10), 1092-1097.
- Bravata, D. M., Smith-Spangler, C., Sundaram, V., Gienger, A. L., Lin, N., Lewis, R., … & Sirard, J. R. (2007). Using pedometers to increase physical activity and improve health: a systematic review. Jama, 298(19), 2296-2304.