Peeing/ Exercise

My LO is 18 months. I recently started attending a Trampoline Class @ the local gym. It requires you to jump on the trampoline doing different moves. I can pee before the class starts but still manage to have wet pants by the end of the class. I wore a pad last class and I was still wet! 😖 any other ideas ? I really enjoyed the class minus the part of wondering if anyone could see the wetness. Thankfully I wore silly pants and you couldn't tell. So embarrassing still! HELP!