Update 2/21/20. Is it possible that a simple fitness test you can do right now in your home, might predict your risk of heart disease? That's what some people are saying in light of an interesting study that was published a few years ago and it even got some publicity on the Dr. Oz Show too. The test involves measuring the flexibility of your hamstrings. Because it got so much publicity, I even sometimes discuss it in the classes I teach. Let's take a look at this clinical study and see if we can make some sense of it.
What Was The Study?
The study was titled Poor Trunk Flexibility Is Associated With Arterial Stiffness and was published in the Journal of Physiology in 2009. It involved 523 people from 20-83 years of age. It included 178 men and 348 women. None of the people were “obese” with BMIs (body mass index) of less than 30. None of the people had any obvious signs of chronic disease either.
The people were grouped into the following:
- Age 20-39 were the young group
- Age 40-59 were the middle-age group
- 60-83 were the older group
The people underwent a Sit And Reach Test, to determine hamstring and low back flexibility. Basically, you sit on the floor, bend forward at the hips (no rounded back) and try to touch your toes.
The Sit and Reach test is common in health clubs around the world. The researchers had the people make two attempts and the best of 2 trials was recorded. Here is a video of the test:
The researchers also tested the people's aerobic fitness using an exercise bike rode to exhaustion. They also tested leg strength (as a test of total body strength) too
Not everyone in the study did all the tests, but a large number of people did.
Researchers noted that in middle-aged and older adults, poorer flexibility in hamstrings was associated with having more stiffer blood vessels.
Interestingly, this correlation was not seen in the younger people who participated in the study.
This might seem odd except that the younger people also had greater aerobic abilities than their middle-aged and older counterparts.
Since aerobic exercise is well known to improve flexibility and improve blood vessel elasticity, I wonder if this might be the reason for what the study found?
In other words, did the older and middle-aged adults have less flexible blood vessels (and less hamstring flexibility) because they exercised less than the younger people?
Blood Vessel And Muscle Stiffness: Is There A Connection?
In the study, the researchers provided several reasons to try to explain the results they were seeing. For example, it was speculated that since blood vessels and muscles contain similar proteins such as collagen and elastin, was it possible that what makes muscles stiffer, also makes blood vessels stiffer too?
Another possibility might be related to higher blood pressures as we get older. The older and middle-aged people in the study did have higher systolic blood pressures than younger subjects. Higher blood pressures can stiffen blood vessels, which in turn can contribute to cardiovascular disease.
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Why Are Stiff Blood Vessels Bad?
Less flexible (stiffer) blood vessels can raise blood pressure, putting more stress on blood vessels, and causing them to get hard and rigid. This, in turn, makes the heart work harder than it needs to. It also adds to stress on the kidneys and can contribute to kidney failure as well as strokes.
Because kidneys help control blood pressure, as they start to fail, this adds to the pressure on the blood vessels, making them even more stiff and easily damaged.
It really is a vicious cycle and that's why I think this study got so much attention because if the results hold true, it means we would have a simple way to “see” how well our blood vessels might be doing.
Ways To Lower Blood Vessel Stress
Suppose you do the sit and reach test today and find you are pretty inflexible. What do you do then? Well, besides talking to your doctor about the best way to proceed for you, are there any natural ways to help reduce the stress on your blood vessels?
Remember blood pressure and blood vessel stress are related to each other. So, one way to help your blood vessels is to try to lower your blood pressure. If you can lower your blood pressure, then this reduces the stress on blood vessels.
Just for reference, here are ranges of blood pressure and what they mean:
- Normal: less than 120/80
- Pre-hypertension: 120/80-139/89
- High blood pressure: greater than 140/90
Notice that 120/80 isn't called “normal” any longer. Evidence suggests that having a BP of 120/80 puts people at increased risk of getting high blood pressure (hypertension). High blood pressure, in turn, is the #1 cause of strokes. Newer BP guidelines call for identifying high blood pressure at 130/80.
So, by lowering blood pressure, we cut back blood vessel stress and in doing so, reduce blood vessel stiffness. This, in turn, helps cut back on the diseases it can lead to.
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Here are some ways to help:
1. Don't smoke – or quit if you do smoke. Smoking causes the blood vessels to squeeze together. This puts more stress on the blood vessels and the entire cardiovascular system.
I'm very passionate about getting everybody to not smoke. Smoking -related cancers killed both of my parents (they died less than 3 months from each other). Please quit for your family.
2. Exercise. Exercise can not only help boost nitric oxide production, but it also helps to realign the cells that make up the blood vessels (called the endothelium). When these cells are aligned better, it helps the blood vessels stay more rubbery and elastic. This helps them respond better to nitric oxide.
What nitric oxide you ask…?
3. Nitric oxide. Nitric oxide (also called “NO”) is a gas that causes the muscles in our blood vessels to relax and expand. This makes it easier for the blood to pass through the blood vessels. This, in turn, means less blood pressure stress is placed on the blood vessels. This also means less damage to the blood vessels. Less damage = less cardiovascular disease.
One of the best ways to improve nitric oxide levels is through exercise. Any type of exercise can help.
Some people turn to supplements to raise nitric oxide levels. While many “NO supplements” exist, I believe many of them lack good proof. That said turmeric does appear to raise nitric oxide.
There are many turmeric supplements out there
4. Eat more potassium. Most of us know that sodium can raise blood pressure. But, how many know that potassium can lower it? Most people eat too much sodium and not enough potassium.
Foods that have potassium include fruits and vegetables. There is even a diet called the DASH Diet that has been clinically shown to reduce blood pressure.
5. Beet Juice. There have been some interesting studies that suggest that drinking beet juice can raise nitric oxide levels. Many of these studies involve beet juice helping athletes exercise longer. This has led to several beet supplements being sold such as this supplement. If this is something you're interested in trying, I'd say invest in a good juicer and juice your beets with other fruits and veggies.
6. Yoga. There is evidence that doing Yoga can help the endothelial cells of our blood vessels. I think any kind of stress reduction works just as well.
It is also worth noting that meditation is part of the Dr. Dean Ornish plan, which has been shown to reverse heart disease.
7. Floss. Flossing and brushing your teeth help the blood vessels stay healthy.
The good news is that it does appear blood vessel damage can be reversed to some degree. It takes time and patience though. To help narrow down where I think you should spend your time helping your blood vessels, I'd say focus on the big picture of exercise, eating more fruits and vegetables, not smoking, and having good oral hygiene. I think you see the most benefits there.
So, Tight Hamstrings And Heart Disease: Yes or No?
One of the things I try to live by is that the simple answer is often the correct answer. Remember that the younger people in this study, in addition to having better flexibility, also had better exercise conditioning too. Could it be that lack of regular exercise leads to both less flexible muscles and less flexible (stiffer) blood vessels? I think this might be the big take-home message from the study.
So, if you do try the sit and reach test and can't touch your toes, take it as a sign to try to improve your overall health. That doesn't mean go run a marathon but rather, just go for a leisurely walk. If you can add in the other things we discussed here, that's even better. At the end of the day, doing any kind of “exercise” is better than none – both for your flexibility and everything else too.