It may come as a surprise that shooting a basketball requires more than just arm movement. When shooting a basketball, the most crucial muscle group to activate is the core, which mostly consists of the abdominis muscles. The contraction is isometric since there is no movement required in just engaging and having a strong core. This means that the abdominal region has to be tight for long periods of time. Other muscle groups such as the chest or leg muscles can also be used when shooting a basketball. However, since these areas of the body are capable of greater range of motion, they're usually not kept as tight as the core during practice or games. In general, if you want to be able to shoot with accuracy, then it's important to work on your core strength. This will ensure that your torso is stable and able to keep up with the moving ball.