Sometimes, when practicing katas Splinter was reminded of his early days, when his sons had been still infants and he had been re-learning Ninjitsu. The human and rat were alike, that was no lie, but the underlying structures of muscles and bones and the addition of his tail made it necessary for Splinter to retrain himself in his craft.
back then he'd done so for both maintaining health and remaining fit and limber to be able to forage for the long hours he needed to, to ensure he found food and items they needed day to day.
And to one day teach his sons.
Now, whilst the very early morning crept by, almost something unnoticed underground were they lived save the clocks they had, he practiced mostly to loosen up his body for their morning session of training. With age came a little stiffness in joints ad he found he needed the slow going through the motions of the katas to warm up...