If theres one thing I have noticed while doing my first steps of parkour and sparring its that relaxing more joints looks nice and keeps a good flow. My friend keeps all joints moving or held and looks like a robot whereas I have a tiny bit of flow. Just a little basic tip but some people miss out on it.
A good thing i learned over the years is learning forward a bit is a good touch when running for the spar if needed, you need to find that "soft spot" that allows you to run forward with good momentum, but not so much you fall over on your face. Balance is also important as you want to be able to get back up onto your feet when needed and other things, relaxing can help in some frames as well as it can help your movements flow a slight bit.
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