I run a lot and quite often when I am out, I get the urgency to use the toilet. What could be causing this do you think?

This can often be linked to magnesium deficiency, which shows up in runners after a while if they are not taking care in supplementing it. Most of the time it happens if you're doing long runs, rather than lower levels of activity; however, it depends on how deficient you are to start with. This is why it may show up after a while, which can be puzzling.

I would recommend taking around 200-400mg of magnesium daily. Some other tips would be to go for a liquid or powder formula which means the magnesium will be better absorbed. Also, certain forms of magnesium are thought to be more readily absorbed than others so a pure magnesium citrate product may be preferable to magnesium oxide, for example, which isn't thought to be so well absorbed. Magnesium gluconate is another favourable option to look out for.