Can Exercise Lead to Heart Disease?
Researchers are Confused
From The Denver Post, Thursday, May 31, 2012 edition:
By analyzing data from six rigorous exercise studies involving 1,687 people, the group found that about 10% got worse on at least one of the measures related to heart disease: blood pressure and levels of insulin, HDL cholesterol or triglycerides. About 7 percent got worse on at least two measures. And the researchers say they don't know why.
The group referred to in the article is a collective of well known exercise researchers (I do not know names. The article does not say), and one of them wrote a scientific paper justifying national guidelines that promote exercise for everybody. To them, and other researchers, the fact that 10% of the study participants developed heart disease precursors from steady, rigorous(?) exercise makes no sense. In spite of the conclusions, the researchers still recommend exercise for everybody, but now they suggest that exercisers get their heart disease risk factors checked regularly.
Do I think that the conclusions of he study are fairly accurate? Yes.
Exercise is a Stressor
I understand why the researchers are confused. The study did not take into consideration all the the variables needed draw a better conclusion. It was too general. For example, it is not clear that the participants did vigorous exercise (although I suspect they did. I will explain why in a minute), duration, intensity, frequency, and of course the all important diet. All of these factors have an impact. They need to be accounted for to come to definitive conclusions.
Nevertheless, I do believe the study is fairly accurate in claiming that exercise can lead to heart disease. Let me explain.
We all know exercise is good for us. It can help regulate insulin levels, regulate body-fat, increase energy, and maintain a good quality of life longer into old age.
What most people do not realize, and I will put many personal trainers and fitness professionals in this camp, is that exercise is a stress on the body, just like having a cold, working long hours, or going through a divorce would do. Too much exercise, and specifically too much vigorous exercise release the stress hormones to deal with the damage. On the other hand, too little exercise does not give a "stimulus" to the body for it to adapt and better cope with the daily demands placed on it.
How the Body Adapts to Exercise
Every time you exercise, and especially when you do intense exercise that challenges you above the anaerobic threshold, the body gets pretty beat up. The fast twitch fibers are used and the glycogen stores in the muscles get burned up. It is nothing to fear, for we want to do this to our body. What we need to do, and what most people do not do, is allow the body to recover from the workout. Here is why. There is a threefold process that the body goes through after every hard workout:
- Restore it's original energy.
- Restore it's original level of strength.
- Super-compensation. I.E. adapt by getting a little stronger and more able to work longer and harder above the anaerobic threshold.
These three steps happen in exactly this order. You cannot short circuit this process. You cannot change the order of the recovery. You need to give it time to go through these processes. How much? At least 48 hours. Maybe even 72 hours if it was a hard workout, and you are very strong. I have to credit Arthur Jones and Dr.Ellington Darden for really driving this point home. They did research with thousands of trainees for over 50 years, and Dr. Ellington Darden still does research and writes about it. They have found that hard, brief exercise and lots of rest provides the body with the optimum environment for muscle growth and overall health.
So, what happens if you train hard for too long? The body starts breaking down. You over train. You can over train when you are younger, and you can over train for a while without the negative effects, but if you do it too long, you will suffer the consequences.
My Anectdotal Insight
Like many young enthusiastic trainees, I did what every gym rat did and preached. The mantra was that you needed to spend at least an hour a day in the gym, and when you hit your plateaus, you increase your volume. This simply meant that you added more sets, split your body parts up, and hammer your body even more frequently. I did not get very strong training this way. After a few months, I would quit because I would be chronically tired and bored. Once I started applying the briefer, more intense workouts with much more recovery between exercise sessions, I made good progress. But my personal lessons did not stop there. A few years after training this way, I assumed that I should have been farther along, so I reverted to a split routine for 2 weeks. This time I did it in a high intensity fashion rather than the usual way people do a split routine (Taking all of my sets to failure, and minimal rest in between sets). By the end of the first week, I got sick. This was in summer, so it wasn't the usual cold and flu. I also got canker sores in my mouth. I never had them before. I had to take 4 days off from work to recover, and it was another week before I could get back into the gym for even a light workout. Furthermore, it was another week before I was able to train with my normal weights. In short, I lost 4 weeks of consistent training from being overzealous. Over time I learned how to listen to my body and adjust my intensity along with rest and recovery to stay healthy. A good benefit from my profession as a personal trainer is that not only do I get to see the outcomes of diet and exercise on my own body, but that of many other people I have worked with. Let me tell you, I garnered much wisdom this way, especially concerning the effects of over training. Some of my clients had one of the following problems: fibromyalgia, chronic fatigue, low exercise tolerance (physically, not mentally), and of course, the usual arthritis and tendonitis. Almost all of these symptoms were traceable through many questions to over training in the client's youth. Even though I do not have personal experience with clients showing heart disease risk from exercise, I believe it can happen. Years ago I read a study done on long distance runners, and the study found that a good percentage of them were dealing with not only heart disease, but also cancer (I apologize for not citing the particular study, for I lost the paper work over the years). This, however, offers further evidence that one can do too much exercise.
Exercise as Medicine
Remember, exercise is a stressor on the body. It will trigger a hormonal response. In validation of Arthur Jone's earlier findings, later research found that during intense exercise, the body will secrete growth producing hormones such as testosterone and human growth hormone (This is good. We want to encourage this response), for about 45 to 50 minutes into an exercise session. If a trainee continues to train hard after that, the body stops producing these hormones and starts producing cortisol. Cortisol numbs the pain, but it also tears down the body. So, in essence, the hard work a trainee puts into his body the first 45 minutes will be mostly for naught if he continues for more than an hour. If this is carried out for many years, the outcome will become quite obvious.
As a trainer, I have a different philosophy regarding exercise. I do not believe that if some exercise is good, more is better. I regard exercise as medicine, in that you need to give your body the appropriate dose. For example, a doctor prescribes just the right amount of anti-biotic to cure someone. If he gives to little, the bacteria comes back. If he gives too much, the bacteria will grow immune to it. Both outcomes have a negative impact on the patient. Exercise is the same way. Too much and the body starts breaking down. Too little (mostly in relation to intensity), and the body has no reason to adapt and get stronger. The right dose, on the other hand, leads to optimal fitness and health.
Back to the Study
So even though the researchers are both surprised and confused about their findings, I think the study has relevance. They are on the right track. They now need to factor in some of the other variables I mentioned previously to gain more clarity to their findings. I am confident that if they do that, they will find a connection with over training and the aforementioned heart disease precursors.
Nobody questions the need for exercise, along with a good diet for long term health. Fitness enthusiasts, however, must learn to pay better attention to what type of exercise they do, as well as the duration, frequency, and rest that is needed for good health. Over training is just as bad on the body as under training. Train hard, but limit it to under 45 minutes, and take time off to recover. This advice bodes well for endurance athletes as well. As an example, distance runners would do well by cutting the volume down (I would venture that most trainees would benefit if they cut the volume in half), doing it harder, and allow more days off between exercise bouts. Remember, the most important thing is to stay healthy.