If you don't have a bar, do these reverse crunches instead.
- Start by hanging on a pull-up bar with your palms facing out, or use the ab straps and hang with your arms inside of them. Use a box or bench if you need help reaching the bar.
- Pull your shoulder blades down your back to keep your shoulders away from your ears.
- Engage your abs as you simultaneously lift both knees up to your chest with control.
- Lower your legs slowly, and return to the starting position. This completes one rep.
- Complete as many reps as you can in 45 seconds, then take a 15-second rest.