When is sex too stressful for your heart?


Tuesday, Nov 15, 2011
The Business Times (Singapore)
When is sex too stressful for your heart?
By Dr Michael Lim

While having sex is a normal part of life, many wonder whether their heart can continue to withstand the excitement of sex when they grow older.

Those with heart disease worry about the risk of precipitating a heart attack during sex.
Many with heart disease have associated risk factors such as diabetes mellitus, hypertension, smoking and medication, which may impair the ability to engage in sex.

While the use of drugs such as Viagra may alleviate the situation, a common concern is the impact of such drugs on those with heart disease.


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Sex as exercise

One website claimed that having sex three times a week is like having run 48m a week. While this is far fetched, sex does burn calories. 

With sexual arousal and physical exertion, adrenaline increases and the heart-rate and blood-pressure increases.

Most studies have shown that, despite the perception of sex being a vigorous physical activity, the heart rate generally remains below 130 beats a minute, and systolic blood pressure below 170, while having sex with a familiar partner.

Researchers comparing the effects of treadmill testing and private sex at home on the heart found that on an intensity scale of 1 to 5 , with 5 being the highest level of intensity as perceived by the participants, men perceived treadmill testing as 4.7 and sex as 2.7.

For women, sex was perceived as even less intense.

On the average, middle-aged couples have sex about twice a week, each episode lasting about 15 minutes, and burning more than 50 to 80 calories depending on the intensity of sex.

Activities that will burn about 50 calories will include running up and down the stairs for three minutes, or playing tennis for six minutes.



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Will sex increase the risk of heart disease or stroke?

Though some people get headache during sex and worry about getting a stroke, a study published in the Journal of Epidemiology and Community Health, found that frequency of sex was not associated with stroke in the 914 men they followed for 20 years.

A 10-year study on the sex habits of about 2,400 men in a town in Wales showed that those who reported the most frequent sexual activity were only half as likely to suffer a stroke or heart attack during that time.

Hence, from an epidemiological perspective, sex does not increase the long-term risk of heart attack or stroke.

This could be partly explained by the reduction of stress and blood pressure with sexual activity. Studies reported in the journal Biological Psychology showed that cohabiting participants who had frequent sexual intercourse had better response to stress and lower diastolic blood pressure .

Sexual activity and orgasms increase the levels of the hormone oxytocin (also termed the 'love hormone').

Higher levels of oxytocin is associated with the urge to bond and with the feeling of generosity. As the level of oxytocin hormone increases, endorphins also increase.

Endorphins have morphine-like effects on the brain and hence the sensation of pain declines. The oxytocin released during orgasm also promotes sleep.

Hence, you should not be surprised as to why your partner falls asleep so easily after sex. There is substantial data that getting adequate sleep is associated with a lower risk of heart disease and stroke.


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Can sex cause a heart attack?

In a study published this year in the Journal of the American Medical Association, researchers from Tufts Medical Center in Boston, concluded that exercise and sex can increase the risk of heart attack and sudden cardiac death, although the increased risk is small and transient.

The risk is higher for those who exercise infrequently compared to those who exercise regularly.

The researchers pooled together smaller studies that compared the risk of heart attacks and sudden death when participants were exposed to physical activity and engaged in sexual activity to times when they were not.

The study found that episodes of physical activity increased heart attack risk 3.5 times and risk of sudden cardiac death nearly five times.

Sexual activity increased heart attack risk 2.7 times but there was no data available on the link between sex and sudden cardiac death risk. The relative risk is a comparison of the risk when participants are exercising or having sex compared to the risk when they are not.

What it means is that physical exercise and sexual activity can trigger the onset of heart attack and sudden cardiac death, but that risk is transient and lasts for the one to two hours during and after the activity.

While the relative risk of a heart attack during sex is 2.7 times, the absolute risk ( that is, the probability of the heart attack or sudden cardiac death actually occurring in an individual) is extremely small, at least during conventional sex with a familiar partner.

To look at it from another perspective, for a healthy 50-year-old man, the risk of having a heart attack in any given hour is about one in a million. Sexual activity doubles the risk, but even then, the risk is minuscule - just two in a million.

A study published in Lancet by Belgian researchers this year reported that 2.2 per cent of heart attacks is related to sexual activity.

The million-dollar question for many men with heart disease is, 'What is the risk of getting a heart attack during sex?'. Yes, the risk is increased by 10 times compared to healthy men but even with this increased risk, the likelihood of getting a heart attack during sex is only 1 in 50,000.


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By Dr Michael Lim



ABCs of having sex safely

Most people with heart conditions want to know when they should avoid sex, and when they can begin having sex again.

Avoid sex if you are unwell or if you detect symptoms of heart disease such as shortness of breath or chest tightness on exertion. If these symptoms occur during sex, stop immediately.

Not uncommonly, doctors are confronted with the question: 'Is it safe for me to take Viagra?'

Common drugs for males with erectile dysfunction (resulting in inability to complete sexual intercourse) include sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis).

For those with heart disease, being able to exercise up to a heart rate of 130 per minute without any heart symptoms will generally indicate that it is safe to have sex, even with the use of such medication.

There is one very important contra-indication - those who take nitrate medications cannot take these drugs.

Simply put, if you feel well after walking up the stairs for at least three floors, you can safely assume that your heart can withstand the 'stress' of sex.

Dr Lim is medical director at Heart, Stroke & Cancer Centre. He is also editor-in-chief, Heart Asia, British Medical Journals Publishing Group chairman, Scientific Advisory Board, Asia Pacific Heart Association honorary professor and senior medical adviser, Peking University Heart Centre.