I can walk 5 km at most, and then I have to urinate. When I start walking, I have an empty belly, but I cannot control urine buildup. How do professional racewalkers handle this? I see in videos that racewalkers drink water during the race and still walk for at least 1 hour (50k racewalkers walk for 4 hours!), never stopping at the restroom! Please help me as this is a hurdle for me!
That does seem to be a medical condition. Personally, from doing long-distance races (running/triathlon), some for 7+ hrs there is usually not much issue for less than 4 hrs. On a 7hr race, I will stop for 1 bathroom break, but do know some (especially more competitive folk) that will urinate on the go to save time. The Videos are also edited to hide these things, there was a pro cyclist that was captured dropping back from the pack and urinating from his bicycle this year without it being edited out but it is likely because it was being streamed live.
Typically, I take in a bit less liquid than I sweat out and drink a whole bunch immediately after the races. So when you are active, all the liquid you are taking in does not only end up as urine but also sweat.
First thing, I would get it checked out. If there is nothing wrong, then consider taking a bathroom break or urinating on the go if you really have to. If you do choose to go that way, remember to pick up extra water at the water stations and rinse it off...