Exercises For Great Legs

I have just started learning a form of kenjutsu, though I have many years experience in other martial arts. After doing a cutting exercise for 15-20 minutes, I noticed that when I straightened out of the stance and put weight on my back (left) leg, it wouldn’t stop shaking. When I bent it, it was fine, but straightening the knee would make my whole leg tremble. This lasted for hours after class, diminishing over time.

Chudan is a swordsman stance where the weight of the body is distributed evenly between the front and back legs. Before I knew this, I did the exercise incorrectly, shuffling back (putting most of the weight on the back leg), shuffling forward (transferring weight to the front leg) and then returning 60-70% weight to the back leg. I have plenty of experiences with other stances and this has never happened to me before. Could anyone tell me what was happening and how to prevent/minimise it in the future?

you’re over trained your legs, and probably while standing in Chudan… you also stand in a wrong position ex: your knee is bent forward too much so if you take a straight line between your toes and your knee it will be over your toes… i see most of this problem in these kind of stance, the student don;t want to sink their hips more, so they bent their knee more. to make your stance more stable you must find your center of gravity and sink your stance to it. even when you move… never lose your center, it makes your movement more fluid just by sinking your weight in to your center.
Bent your "gua" (area between your thigh and your hips) more…your leg must be forming a 90 degree angle this is call sinking.