Back pain killing your sex life? Study reveals best positions to save your spine

Contrary to popular belief, spooning is not always the best sex position for those with a bad back, according to new research from the University of Waterloo. For the first time ever, scientists have successfully documented the way the spine moves during sex and discovered exactly why certain positions are better than others when it comes to avoiding back pain. The pioneering study combined infrared and electromagnetic motion capture systems to track how ten couples' spines moved when attempting five common sex positions. The findings were used to create an atlas, or set of guidelines, that recommends different sex positions and thrusting techniques based on what movements trigger a patient's pain. Pictured: Professor Stuart McGill demonstrates the motion of the spine during sex.  
Credit: University of Waterloo

Contrary to popular belief, spooning is not always the best sex position for those with a bad back, according to new research from the University of Waterloo.

For the first time ever, scientists have successfully documented the way the spine moves during sex and discovered exactly why certain positions are better than others when it comes to avoiding back pain.

"Any family doctor will tell you that couples often ask them how to manage their back pain during and after sex. Many couples will remain celibate because one night of love-making can lead to months of back agony," said Professor Stuart McGill, of Waterloo's Faculty of Applied Health Sciences. "Until now, doctors have never had any hard science to base their recommendations upon."

The pioneering study combined infrared and electromagnetic motion capture systems -- like those used in the creation of video games -- to track how 10 couples' spines moved when attempting five common sex positions. The findings were used to create an atlas, or set of guidelines, that recommends different sex positions and thrusting techniques based on what movements trigger a patient's pain.

"Before now, spooning was often recommended by physicians as the one position that fit all. But as we've discovered, that is not the case," said Natalie Sidorkewicz, a PhD candidate at Waterloo and lead author on the paper. "Sex positions that are suitable for one type of back pain aren't appropriate for another kind of pain."

The atlas recommends that men who are flexion-intolerant -- meaning those whose back pain is made worse by touching their toes or sitting for long periods of time, for example -- replace spooning with doggy-style sex. The guide recommends that these men use a hip-hinging motion rather than thrusting with their spines.

"For the first time ever, we now have very solid science to guide clinicians on their recommendations for patients who suffer debilitating back pain, but still want to be intimate," said Sidorkewicz. "This has the potential to improve quality of life -- and love-life -- for many couples."

According to Statistics Canada, four of every five people will experience at least one episode of disabling low back pain in their lifetime. Up to 84 per cent of men with low back pain and 73 per cent of women report a significant decrease in the frequency of intercourse when suffering back pain.

The study also shed light for the first time on the mechanics of the male orgasm. Electrodes hooked up to the male participants' muscles revealed that it is abdominal and buttock, not back muscles, that are most active during orgasm. Spine motion, on the other hand, varied with the individual. For some males, a drastic increase in flexion or extension was seen, while for others spine motion did not change much at all.

"Many of the back pain patients that we see have told us that they experience elevated levels of pain during orgasm, to the point where they will avoid having one during sex with their partner," said Sidorkewicz. "These initial findings help us to begin to understand what might be provoking their pain during the moment of climax."

A paper documenting male spine movement was published in the journal Spine. Female findings are expected to be published in the coming months. The next phase of the study will involve recruiting patients with hip pain and additional categories of back pain to further develop the guidelines.

Source: University of Waterloo

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CT scans could bolster forensic database to ID unidentified remains

Cranium image reconstructed from CT scans. Credit: North Carolina State University

A study from North Carolina State University finds that data from CT scans can be incorporated into a growing forensic database to help determine the ancestry and sex of unidentified remains. The finding may also have clinical applications for craniofacial surgeons.

"As forensic anthropologists, we can map specific coordinates on a skull and use software that we developed -- called 3D-ID -- to compare those three-dimensional coordinates with a database of biological characteristics," says Dr. Ann Ross, a professor of anthropology at NC State and senior author of a paper describing the work. "That comparison can tell us the ancestry and sex of unidentified remains using only the skull -- which is particularly valuable when dealing with incomplete skeletal remains."

However, the size of the 3D-ID database has been limited by the researchers' access to contemporary skulls that have clearly recorded demographic histories.

To develop a more robust database, Ross and her team launched a study to determine whether it was possible to get good skull coordinate data from living people by examining CT scans.

The University of Pennsylvania Museum's Morton Collection provided the NC State researchers with CT scans of 48 skulls. Researchers mapped the coordinates of the actual skulls manually using a digitizer, or electronic stylus. Then they compared the data from the CT scans with the data from the manual mapping of the skulls.

The researchers found that eight bilateral coordinates on the skull -- those found on either side of the head -- were consistent for both the CT scans and manual mapping.

"This will allow us to significantly expand the 3D-ID database," Ross says. "And these bilateral coordinates give important clues to ancestry, because they include cheekbones and other facial characteristics."

However, the five midline coordinates the researchers tested showed inconsistencies between the CT scans and manual mapping. Midline coordinates are those found along the center of the skull, such as the bridge of the nose.

"More research is needed to determine what causes these inconsistencies, and whether we'll be able to retrieve accurate midline data from CT scans," says Amanda Hale, a former master's student at NC State and lead author of the paper.

This research may also help craniofacial surgeons. "An improved understanding of the flaws in how CT scans map skull features could help surgeons more accurately map landmarks for reconstructive surgery," Hale says.

Source: North Carolina State University

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Do women and men ride differently? Horses cannot tell the difference

Horses seem to be truly gender-neutral. It doesn't matter to them if their human partner is female or male.
Credit: Juliane Kuhl / Vetmeduni Vienna

Scientists at the Vetmeduni in Vienna have analysed how horses are affected by the sex of their riders. Various parameters of stress were determined in horses and their riders when they covered an obstacle course. The results were surprising: the level of stress on a horse is independent of whether a man or a woman is in the saddle. Furthermore, the stress responses of male and female riders are essentially the same. The results have been published in the Journal of Comparative Exercise Physiology.

For centuries, horse riding was largely restricted to males. The previous situation is in stark contrast to the present day, when nearly 80 percent of riders are women. Modern-day equestrian sports are unique in that men and women compete directly against one another at all levels, from beginners in gymkhanas to national champions in the Olympic Games. "For this reason it is interesting to consider whether a theory of riding that was developed exclusively for men can be applied to women," explains Natascha Ille, the first author of the recent publication.

A rider is a rider

As Ille notes, "It is often assumed that women are more sensitive towards their horses than men. If this is so, male and female riders should elicit different types of response from their horses." Ille, Christine Aurich and colleagues from the Vetmeduni Vienna´s Graf Lehndorff Institute tested this notion by examining eight horses and sixteen riders, including eight men and eight women. Each horse had to jump a standard course of obstacles twice, ridden once by a male and once by a female of similar equestrian experience. The scientists monitored the levels of stress in the horses and their riders, checking the amounts of cortisol in the saliva and the heart rates.

The results were unexpected. The level of cortisol in horses' saliva increased during the test but the increase was not affected by the sex of the rider. The horses' heart rates also increased as a result of taking the course but the increase was irrespective of the human partner in the saddle. The tests on the riders gave similar conclusions. Again, the level of cortisol in the saliva increased but there was no difference between men and women. The riders' pulses sped up when the horses switched from a walk to a canter and accelerated further during the jumping course. But the heart rate curves for male and female riders were close to identical.

The distribution of saddle pressure is the same for male and female riders
In a second experiment, Ille and her colleagues studied the pressure exerted on a horse's back via the saddle. As she explains, "Depending on the rider's posture and position, the pattern of pressure on the horse's back may change dramatically." A special pad placed directly under the saddle was used to analyse saddle pressure in walk, trot and canter. Because female riders are generally lighter than males, the saddle pressure was lower when horses were ridden by females. However, the distribution of pressure did not differ and there was no evidence of differences in the riding posture between males and females.

A fair chance for all

So what does all this mean for modern equestrian sports? Aurich is keen to reassure potential competitors that horses are truly gender-neutral. As she puts it, "Assuming that there is no difference in riding ability, from the horse's point of view, it does not seem to matter whether the human partner is male or female. Our results make it extremely unlikely that horses have a preference for riders of one sex over the other. And when male and female riders compete against one another in equestrian sports, all of them have similar chances of doing well."

Source: Veterinärmedizinische Universität Wien

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