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09.03.2011


Stretching versus artery stiffening

Strength training has many positive health effects, but there's at least one negative one: studies show that it makes your arteries stiffer. Creatine supplementation and doing cardio training after a strength workout can reduce the damage, and we wrote about these recently. Today we describe another strategy that probably helps strength athletes: stretching.

Stretching
Stretching versus artery stiffening
Sports scientists working with Motohiko Miyachi, the man who first drew attention to artery stiffening as a result of strength training in 2003 and 2004, discovered that flexibility protects against stiffening of the arteries. Miyachi published the results of the study on which we base this article in 2009. It was an epidemiological study of 526 Japanese aged between 20 and 83.

The researchers measured their subjects' condition and muscle strength. And they used a special instrument the T.K.K.5112 to measure how flexible their test subjects were. The subjects sat on the ground with outstretched legs and had to bend forward as far as possible. The more cm the instrument measured, the more flexible the subjects were.

Flexibility
Among the young people, aged between 20 and 39, flexibility was not a factor. In the group of people aged 40-59 [Middle] and especially in the 60-83 age group [Older], the baPWV - or the stiffness of the arteries was less the suppler the subjects were.


Stretching versus artery stiffening


Flexibility was an independent variable. It made no difference whether the subjects' condition was good or bad, their arteries were suppler the more flexible they were. And, flexibility also lowered their blood pressure.

The findings of the Japanese are not completely new. In 2008 American sports scientists stumbled across the protective effects of flexibility. [Eur J Cardiovasc Prev Rehabil. 2008 Apr; 15(2): 149-55.]

Study
In this study the researchers wanted to find out whether they could cancel out the stiffening effect of strength training on the arteries with cardio training.

They got 13 test subjects to train for 13 weeks with weights. The subjects went to the gym 3 times a week. [Strength training].

Twelve other subjects followed the same schedule but also did aerobic training. [Combination training]. Twice a week, on the days that they didn't do strength training, the subjects ran or cycled for 30-45 minutes at 60-75 percent of their maximal heart rate. Not many strength athletes are likely to be wild about doing this, but never mind.


Stretching versus artery stiffening


Results
The aerobic training cancelled out the negative effects of the strength training, as you can see in the figure above. That's to be expected. But what happened in the control group was most interesting. They only did stretch exercises. [Stretching]. The elasticity of the arteries increased in this group.

You can find details of their stretching programme here.

For the record: it would seem obvious that strength athletes can protect their arteries by stretching. But we haven't managed to find any studies that show that strength athletes also actually improve their cardiovascular health by doing stretching sessions. As soon as we find them, we'll let you know.

Adrenalin and nor-adrenalin
To return to the Japanese study: the Japanese have a theory about how strength training stiffens the arteries. They know that strength training leads to a sharp rise in adrenalin and nor-adrenalin levels in the blood, and suspect that these pep hormones play a key role in the stiffening of the arteries. Stretch exercises, endurance training and aerobic training all lower the concentration of these hormones.

Source:
Am J Physiol Heart Circ Physiol. 2009 Oct; 297(4): H1314-8.

More:
Cardio session after strength workout keeps arteries supple 08.03.2011
Creatine keeps strength athlete's arteries supple 07.03.2011
Strength training stiffens arteries 06.03.2011