The good news on this topic is that it's pretty much all good news. If your feet cramp up when you first start bouncing, it’s usually because your body is learning how to do its job (keep you upright) on a surface that is not only unsteady but designed to challenge your proprioception and balance. That the discomfort you’re feeling is tension caused by gripping the muscles in the bottoms of your feet in an effort to stabilize your body on the trampoline.
Have you ever tried balancing on one leg with your eyes closed? If you haven’t, or can’t remember what it feels like, take a moment and give it a try. Unless you have superhuman balance - which, props if you do - you’ll feel some wobbles in your standing ankle and foot. Those wobbles are information; your body is taking inventory of where you are in space and what kinds of shifts need to be made to keep you balanced. When you’re on your trampoline, imagine that same wiggly action happening inside your sneakers, quickly and more minutely every time your feet hit the trampoline. Enter, foot cramping.
Especially as you get started with bounce, remember that you are not alone. What you are experiencing is a perfectly normal sensation, and it’s something that will dissipate with time and continued practice. If after the first ten times you bounce on your trampoline, you’re still feeling uncomfortable through the bottoms of your feet, it could be a sign that you’re in need of a new pair of sneakers or a different style that offers more support.
Time, and new sneakers, can heal many things, but instead of waiting it out there are a few practices you can adopt that will ease some of the initial discomfort as well as help improve your overall bounce form and confidence. Although the foundation of bounce is about pressing down through the bottoms of your feet, focus an equal amount of energy into engaging your core. By wrapping your abdominal muscles both in and up, as if someone is tightening a wide belt around your waist, you’re doing two things that will aid in relieving your soles. The first is creating opposition in your body. When you activate your core, you’re recruiting your most central muscles to lift up and away from your trampoline as your feet press down. This allows you to lighten the load of your landing so your feet aren’t doing all the work on their own. Another thing you can do, and what I feel is most important of all, is try your best to relax. Realistically, gripping your arches and toes inside your sneakers is not doing anything to actually help you learn how to bounce or become stronger at it. The more you can let go of any nerves that are creeping into your mind, or manifesting within your body, the sooner you’ll feel comfortable on your trampoline and the sooner you’ll be free from unwanted, uncomfortable feelings in your feet while you bounce.