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Not tonight darling, I have a backache

Don't let a bad back get in the way of your love life. Dr Karl reviews new research that can help - men, at least.

I was simultaneously relaxing in the bath, and browsing my way through some light scientific and medical reading when a paper in the latest edition of Spine caught my eye.

It dealt with the important topic of how to minimise lower back pain — for men — during sexual intercourse.

The paper was called 'Male Spine Motion During Coitus and was authored by Drs Sidorkewicz and McGill from the Department of Kinesiology at the University of Waterloo in Ontario, Canada.

Now the first thing to realise is that it's not just terrorists who have sex, but that regular people like you and me also enjoy it.

The second thing is that it's good for you, as a consenting adult, to have sex. After all, the musician, Frank Zappa said words to the effect that you can't have too much sex or vegetables — and who's going to argue with Frank.

Furthermore, having sex is a well-recognised indicator of your quality of life. Indeed, the World Health Organization's International Classification of Functioning, Disability and Health reckons that sexual relationships are an integral part of your overall health.

Unfortunately, having pain in your lower back will consistently reduce how often you have sex. Indeed, some 34 - 84 per cent of males, as a result of lower back pain, cut back on how often they have sex.

The problem, from a medical point of view, is that we don't know exactly what to recommend to stop back pain from interfering with your love life. Sure, a common bit of medical advice is to use the 'side-lying' or 'spooning' position — but this advice is based on theoretical grounds, not actual physical research.

Until now, there have been no deep studies on the link between different sexual positions and different back problems.

This is why Drs Sidorkewicz and McGill brought 10 heterosexual couples, with established sexual relationships, into their spine biomechanics laboratory.

In this study, the researchers were mainly concerned with back-and-forth movements. Back pain differs with age. Bending forward is called 'flexing'. Younger people with lower back pain tend to have trouble with flexion. Bending backward is called 'extending', and it's generally older people with back pain who have trouble with extension.

The researchers then got each volunteer to stand straight, bend in flexion and extension, and bend side-to-side. This gave each volunteer's maximum range of motion.

Then the good doctors invited the couples to have sex in five randomly assigned sexual intercourse positions. These positions were the previously mentioned 'side-lying' or 'spooning' position, two variations on the 'face-to-face' or 'missionary' position, and two variations on the 'doggie' position. This position, in which the woman is on all-fours, and the man is behind, they called the 'quadruped' position.

They placed reflective dots at various strategic positions on the volunteer's bodies, and then tracked their movements with eight special infra-red motion-capture cameras — while they were getting down to 'it'.

Once each couple had reached their 'natural coital speed and/or rhythm', the researchers collected 20 seconds of data.

They then analysed the data using 'Tukey's honestly significant difference post hoc analysis' to work out the relationship between each position of having sex and movements of the spine.

The results were quite surprising.

First, if lower back pain was worse in flexion, you should avoid the oft-recommended 'side-lying' or 'spooning' position. Instead, you should try the 'doggie' or 'quadruped' position with the woman resting her weight on her elbows, not her hands.

Second, it was possible to modify a potentially painful position into a non-painful position with minor changes — such as shifting your weight from your elbows to your hands, or vice versa.

The details are actually quite important, so I recommend you download the paper if you're interested.

Now don't you love the way this study looked at helping men with lower back pain first. In keeping with the patriarchal society we live in, the researchers are still finishing a separate study looking at helping women with back problems, which results in painful sex. At least they've started — and that's something.

We already know that if you have a bit of chronic back pain, you tend to get a bit cranky. At least if you love another person very much in a special pain-free way, you'll be a bit less cranky ...

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