The principle of the lever techniques in Aikido is to connect to the partner’s shoulder via the grip so that your movement is transferred to the partner’s whole body. To do this, you fix your partner’s wrist and elbow and hold this form until you lead your partner into a throw. In addition to good technique, you need a firm grip for this.
The secret of a good grip is the correct placement of the palm and fingers, as well as the ability to bend the fingers optimally and strongly at the same time. Let’s start with the latter. A simple exercise to strengthen the grip is to first spread and stretch the fingers and thumb of the hand completely. Then, starting from the fingertips, slowly bend all the fingers and thumb into a fist and continue to clench the fingers into a fist with full force for 8-10 seconds before relaxing and spreading them again. Do this a few times until you feel a slight fatigue. The important thing in this exercise is to curl the hand, starting from the fingertips, limb by limb. You should do this very consciously, as it makes a big difference in your grip how you bend your fingers. The rest of the body as well as the breathing remain relaxed during this exercise. After understanding how to curl the fingers properly, you can do this exercise with objects, e.g. with the jo or even incidentally while driving a car or cycling.
After this preparatory exercise, we move on to correct grasping. To do this, grasp the forearm of the other side of the body with one hand just above the wrist. The decisive factor in gripping is maximum contact of the hand with the forearm. First press the palm of your hand onto the forearm until you feel the bones of the forearm. Then enclose the forearm with your thumb and fingers in a large (!) movement starting from the fingertips. Especially the area between thumb and index finger should have the closest possible contact. Mentally, you should grip the inside of the arm (the bones), not the surface.
If you have a good grip on yourself, you will find it difficult to rotate the forearm outwards or inwards against the grip. If you grip your own hand or your partner’s hand instead of your forearm, the principle remains the same. The decisive factor is to use as much of the surface of your own hand as possible and to mentally reach into the depth (= Ki). To do this, you need the technique shown as well as holding power in the forearm muscles, which ensures that you do not lose the grip again as soon as you lead your partner into a movement. Therefore, one should train the strength of the hands regularly. In addition to the exercise shown above, you can also modify the first three Aiki Taiso movements (Kotegaeshi Undo, Sankyo Undo and Nikyo Undo) slightly and hold the end position for 8-10 seconds each with maximum pressure. In doing so, you strengthen your grip as well as your own wrists.
Klaus Heß 07/2021 (translated with DeepL)