New research presented at the 25th annual conference of the European Society for Human Reproduction and Embryology (ESHRE), held in Amsterdam last week, points towards factors affecting sperm quality and male fertility. Frequent sex and avoiding extreme levels of cycling training have both been indicated as playing a key role in maintaining healthy sperm.
In the first study, by scientists at Sydney IVF, Wollongong, Australia, daily sex or ejaculation was found to reduce DNA damage in sperm and to increase sperm motility and may, therefore, boost fertility. These findings apparently contradict previous beliefs that abstaining from sex for a few days before attempting conception increases sperm numbers and therefore increases the chance of pregnancy. The new research found that in 118 men with relatively high levels of DNA damage in their sperm (more than 15 per cent of sperm damaged), daily ejaculation reduced damage in eight out of ten men by an average of 12 per cent. In the group as a whole, damage was reduced from an average of 34 per cent to an average of 26 per cent. The improvement was suggested to be due to the sperm spending less time in the testicles, where it is subject to damage by heat and free radicals.
The researchers believe that these improvements in sperm quality may outweigh the benefits of increasing the sperm quantity by abstaining from sex prior to attempting conception. However, Dr David Greening, who presented the research, warned that 'further research is required to see whether the improvement in these men's sperm quality translates into better pregnancy rates'. The researchers also warn that daily ejaculation over longer periods of time may have a more significant effect on sperm numbers, and that for men with a lower sperm count to begin with, even short-term daily ejaculation may not be the best approach.
In the second study, led by Professor Diane Vaamonde at the University of Cordoba, Spain, the training regimes of 15 men preparing for triathlons (sports competitions involving swimming, cycling and running) were studied and compared to each man's levels of sperm damage seen. Triathletes are known to often have low fertility. All the men had trained on average nine times a week for the past eight years, but only the intensity of their cycling training correlated with the quality of their sperm. 'While all triathletes had less than 10 per cent of normal-looking sperm, the men with less than four per cent - at which percentage they would generally be considered to have significant fertility problems - were systematically covering over 300km per week on their bicycles' explained Professor Vaamonde.
The sperm damage caused by intensive cycling is thought to arise due to the constant pressure on the testicles from the saddle, the heat in the groin generated by the tight Lycra outfits, and the stress of pushing the body to its limits. The levels of cycling done by men who are not following such gruelling training programs is thought to have little effect on sperm damage.