What action incurs a penalty of up to 0.3 in a gymnastics landing?

When it comes to gymnastics landings, brushing the landing surface with one or both hands incurs a penalty of up to 0.3. This is considered a significant deduction because it indicates a loss of control during the landing phase, which is critical in demonstrating a gymnast's balance and stability. A clean landing, ideally executed, should occur without any contact of the hands with the floor. Supporting the body with the hands suggests that the gymnast did not successfully manage their center of gravity upon landing, and such actions can detract from the overall execution and impression of the routine.

The other actions listed lead to different penalties but typically have more severe implications. For instance, supporting on the mat with one or two hands constitutes a more serious error, resulting in greater deductions because it indicates an incomplete and unbalanced landing. Falling onto the mat with knees or hips indicates a significant loss of control and also has a greater penalty attached. Lastly, failing to land on the bottom of the feet first is indicative of an improper landing technique and also incurs significant deductions.

The key reason that brushing with the hands results in a specific deduction of up to 0.3 is that it denotes a lack of finesse and control that judges look for in successful gymnastics execution.