The Karate beginner executes a basic punch with solely muscular strength. As the Karateka tightens his muscles all the way the muscle contracts and work against each other. After training for some time he learns to relax through the punch and tense only at the end. At the next level, he does not even tense at the end of the punch, but aligns and connects his body as the technique is completed. The final level finds the student executing the technique totally relaxed physically, yet connected to his body all the way through the technique and possessing great internal spirit.
This process of evolution is similar in Aikido development. The majority of Aikido techniques can be represented by geometrical shapes of a square, triangle or circle. In the begining the Aikido trainee performs his techniques based on the square concept. A square is a stable and strong shape. Lacking in movement,it is completely grounded and it plays mainly from physical strength.
After a period of sustained practice, he will graduate to the triangle. A triangle can be seen as having two angles at the bottom and one at the point, the two lower angles can be imagined as a stable platform and the angle at the point as the atemi. It can be compared to entering techniques (irimi) giving the impression of direct movement. At this stage the Aikidoka has learned to soften and relax his movements somewhat from his previous square development stage.
At the next level all the techniques assume the circle concept, where the circle evolves to a spontaneously flowing, and continuous spiral. Circles are not stable but as they are constantly moving they never fall (can a ball be made to fall over?). If all the possible circular and semicircular movements around the centre of an Aikidoka are combined into one image, the result is a dynamic sphere whereby the mental attitude of the Aikidoka is centralized and the energy required to carry out a technique is extended outward from the centre.
Advanced level of Karate and Aikido
So, while the first few years of Karate and Aikido are interpreted differently, the evolution of the techniques is quite similar. The end result is that each style graduates from a more structured, hard and rigid state to a more relaxed, dynamic, efficient and economic state. When both styles execute their movements in a relaxed, dynamic and efficient state at the advanced level perhaps the one aspect that differentiates between the two is that the Karateka's movements tend to be linear while the Aikidoka's is more circular