Today, in the Aikido class, our teacher gave an interesting exercise. I was asked to place the palm of my hand on my opponents shoulder, and he was asked to grab above my elbow with both his hands and pull down. I managed to resist, but my hand bent a little and I was straining my arm muscles.
Teacher explained that when you resist with just your arm muscles, then you have to use lot of strength. Then he asked us to imagine that water is flowing from the center of our body through the arms and going out from the palm. The water represents energy.
Now when my opponent grabbed my arm and tried to pull, he was not able to bend my arm. I did not even have to use strength to resist him. Teacher said that when you move from your center it is not easy for your opponent to overpower you.
Teacher also said that it is important to use your center while standing in ready position. He stood with both his hands on the side of his body, and asked two strong guys to lift him. They just lifted him easily. Teacher said that these are strong men and their muscle strength is stronger than his. Then he took position again and asked the guys to pick him up again. This time both the guys were struggling to pick him up. It took them longer and lot of strength to pick him up. Teacher said that if you use your energy correctly (by centering) then your opponent will not be able to get you off balance.