Scientists have discovered that, at least in mice, oxytocin plays a crucial role in muscle maintenance and that the amount of oxytocin decreases with age. Older mice have less of this hormone, and hence it takes more time for them to repair their muscles. By giving older mice a daily injection of oxytocin, their muscle repair capability was strongly improved.
Though this function of oxytocin has not been demonstrated in humans, oxytocin has been approved for clinical use in humans. If these results also apply to humans, it will be useful for elderly people who will be able to live healthier at higher age.
But since oxytocin improves muscle repair capability, there is a possibility that sportsmen will use it as doping. Since sportsmen use their muscles in a very intense manner, their muscles have a higher risk at damages. This is especially problematic during multi-day sport events as the Tour de France or the Fifa World Championship. The faster a sportsman can have his muscles repaired, the better his overall performance will be.
At this moment oxytocin is legal, and could be obtained and used easily, even if the effects on human muscles is unclear. And as long oxytocin is not listed as doping and sportsmen are not tested at this hormone, which also occurs naturally in our body (to make stuff even more difficult); sportsmen will be tempted to use oxytocin.