What might prevent a facedown person with a spinal injury from being able to roll over in the water?

A facedown person with a spinal injury may experience paralysis, which can significantly limit their ability to move or roll over in the water. Spinal injuries can damage the nerves that control movement and sensation, resulting in loss of function in the limbs or even the entire body, depending on the severity and location of the injury on the spine. This paralysis would inhibit any voluntary movement, making it impossible for them to use their muscles to roll over.

In contrast, while anxiety, weakness, and fatigue can affect a person's ability to move, they don't have the same definitive impact as paralysis. Anxiety might cause hesitation or fear, weakness could stem from various issues but may still allow some movement, and fatigue might impair performance temporarily. However, paralysis directly prevents movement, making it the most relevant factor in this scenario.