Doug Wyatt wrote:
Try standing in a relaxed way, with your feet about shoulder's width apart. For this exercize, keep you knees locked & legs straight. If you lift your toes, so you're standing on your heels, your hips shift backwards. Raise your toes enough and it's very hard to balance - try holding this posture for 10 seconds. Very hard! If you do the opposite, raise your heels, so you're up on your toes, your hips shift forward. Because you can push against the ground with your toes, it's much easier to keep your balance and not topple forward. You can probably hold this position indefinitely. What do you train on? Tatami? Canvas? Wrestling mat? Gymnastics mat? Some surfaces are much more forgiving for pivoting on; sticky surfaces kinda beg for pivoting on the heels to save your knees. I would suggest stretching your calf muscles and achilles tendon. At least that way, you can keep your weight forward even if you lift your heels. Good luck.
Valid points Doug, however you may want to try this:
Stand in a relaxed way on your feet as you naturally would stand, it should be possible to maintain perfect balance for approximately a lifetime ( give or take the odd over-indulgence in alcohol
Now if you want to change direction ( say 180 degrees starting in aikido posture ) shift your weight towards your back foot enough to facilitate raising the front foot off the ground, just enough to turn it. Turn the toes of the front foot towards those of the back foot, so just for an intant you are 'pigeon toed'. At this point move your weight over onto the foot that you've turned. This allows the 'back' foot to lift enough to redirect - which it will do on its own ( try it - you'll see ). You are now facing in the oposite direction. No need to rely on surfaces/friction, just good balance, posture and relaxation, no strain or chance of injury.
I have been using this method for many years, and it seem to continue to be effective.