Does caffeine increase the speed at which sperm travels? I'm not even sure if this claim is true, but... This source states that > Caffeine gives both types of sperm a boost, but the Y-sperm would get a little more of a boost. This article reinforces the quote. In fact, this "tip" can be seen all over the internet to preferentially conceive a male rather than a female. My question is how. **What is happening at the molecular to increase the overall mobility of sperm?** It clearly wouldn't work as a neurotransmitter (as it "normally" works).

The cell response for caffeine, is at the molecular level of RyR (Ryanodine receptor), and the main effect could be a temporal rise in Ca+2 cytosolic concentration, so it can change the electrical behavior for the whole cell, and then affect their mobility. But the main area for RyR research is at spermatogenesis, there are a lot of papers like this one, for that topic