Which of the following is a calibration statement that might be used during the step backwards and reach exercises?

The statement regarding the big bend at the waist providing more control while sitting down is a calibration statement that directly addresses the biomechanics of the movement. This type of feedback is crucial in exercises designed to enhance mobility and functional movements. It helps the individual understand how to optimize their positioning to achieve better stability and control during transitions, such as moving from standing to sitting.

In the context of step backwards and reach exercises, emphasizing the mechanics of the individual's movements can lead to improved performance and confidence. By focusing on adjustments like bending at the waist, the statement encourages the participant to become aware of their body posture and alignment, which is fundamental for safely executing movements.

The other choices do not provide specific, actionable feedback related to the mechanics of movement during exercises. They focus on the need for practice, the adequacy of movement, or the notion of scaling down, which are less about immediate biomechanical adjustments and more about general encouragement or modification suggestions. Such general statements may not effectively guide the participant in refining their technique during critical exercises aimed at improving their functional abilities.