Assume the position

PEOPLE with back pain are known for their grouchiness, and it is not helped if they are also starved for sex. Although sex makes serious demands on the spine, no one has taken the time to study how different sexual positions can accommodate different back problems.

But Stuart McGill and Natalie Sidorkewicz of the University of Waterloo in Canada rose to the challenge. They brought ten heterosexual couples with healthy spines into the lab and asked them to have sex using five randomly assigned intercourse positions. These included two variations of the “missionary position”, where the man is on top of the woman and facing her; two variations of the “doggy” position, where the man is behind the woman on all-fours, and the “spoon”, which involves both participants lying cupped together on their sides. The last of these is often recommended by family doctors as the safest for sore backs.

Most back problems in younger folk are triggered by bending forward, a movement called flexion. But as people age, reaching up and back, known as extension, becomes a more common cause. The researchers wanted to see how various sexual positions differentially taxed the spine, so people would know what to avoid.

They used eight infra-red motion-capture cameras to track the movements of reflective dots placed strategically on the participants’ bodies. The cameras monitored the movements for 20 seconds of sex in each position.

Volunteers were then observed while standing straight, bending forward, extending backwards, bending to each side and twisting at the waist. This was to establish their maximum range of motion, so that the strain involved in each sex position could be calculated.

When the data were crunched, the researchers found that—contrary to popular belief—spooning was not a good idea for men with bending-induced lower back pain. Nor was a variant of the missionary position with the man supporting himself on his elbows. Holding himself up with his arms extended was a more spine-sparing option, along with one of the doggy variants. For men whose back problems are made worse by extending up and back, the opposite was true. A separate study on women with back problems is nearly complete.

The research, published in Spine, will be developed into a fuller guide to sexual positions. The team plans to study other options, such as the man lying on his back (the “cowgirl”). People with back pain find ways to do all sorts of activities, says Dr McGill, and sex should be no different. But five positions in one session is pretty arduous, he points out. “You can only do so many.”