Most gyms have a rowing ergometer or "row erg," and most people use it for rowing. Makes sense. But there's more you can do, like these challenging core exercises.

1 – Oblique Twist

• Hold on to the erg seat from the side in a push-up position.
• Once you're stabilized, move to each side. Go just as far as you can control.
• Each side-to-side counts as one rep.

2 – Roll Out

• Step to the back of the roller and grab the seat. While holding the push-up position, push your arms forward.
• Go as far as you can without letting your low back go into extension.
• Too tough? Do it from your knees.

3 – Knee Tuck and Pike

• Place your feet on the seat and assume the push-up position.
• For the knee tuck, bring your knees into your chest.
• For the pike position, bring your legs in while hiking your hips up into the air.

4 – Single-Leg Knee Tuck

• Same as the previous exercise, but only have one leg on the seat.
• Tuck your knee into your chest.

5 – Plank Position Roll Out

• Place your legs on the seat and assume the push-up position.
• Push your body backward as far as you can without letting your low back go into extension.

6 – Resisted Knee Tuck

• Place your legs on the seat and have a partner put the handle of the rower on your feet.
• This is the same as the previous knee tuck but now the rower will provide resistance for the tuck.