India, Aug. 14 -- By Hoani Smith and Conrad Goodhew, University of Cant

The internet's obsession with "maxxing" has turned almost every aspect of self-improvement into a trend.

Young men now swap tips on optimising everything from sleep and appearance to testosterone, longevity and mental performance.

Male fertility has increasingly been drawn into that world, too. Social media is awash with advice ranging from sensible lifestyle changes to more questionable suggestions, such as icing the testicles, eating raw garlic and taking long lists of supplements.

Saunas and ice bath "cold plunges" have become especially popular, promoted as ways to boost testosterone, improve sperm health and increase the chances of conception.

But how much o...