Avoid: A slipped disk
Rounded shoulders, curved back, pulling as hard as possible: This is how many people think they should use the rowing machine, and it makes trained rowers cringe. "I always see people using this machine as an arms-and-back workout," says Esther Lofgren, a current World Champion rower who is training for a spot on the U.S. Olympic Team. And they take the same form from the gym to the lake. It's a blessing that these amateur rowers tire quickly on the water, because, as Jessica Matthews says, this incorrect posture puts pressure on back and spine and can lead to herniated disks.
Do it right: Push back with power from the legs and let the arms and back follow (you should be hinging at the hips). Instead of hunching your shoulders up to your ears, keep a long neck and straight back throughout the stroke.
Read more: More unexpected dangers to avoid at the gym