Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to prevent rowing injuries [title] Improve your rowing technique. [step] Always ensure that you are sitting correctly when rowing. Coordinate your rowing motion and maintain a good posture to avoid back injury.

Ending1: Without rowing, you could damage your lower back or injure yourself. [substeps] Keep stretching before rowing and place your feet in an even position. Ending2: For instance, you should be sitting tall on your seat, with your head up and your eyes ahead. Make sure that your navel is pulled into your spine. Ending3: While rowing, stand with your feet hip width apart and your shoulders lowered to lower your back. Place both of your arms evenly on the top of your head. Ending4: Always be on the bar/bench without your feet directly touching the walls of the water. When rowing, don't lean over your legs, or try to jump forward.

Answer format: ending1/ending2/ending3/ending4