10 Back squats to a box
20 GHD situps
The squats are all the way to the 12″ box, lift your feet off the ground, replant your feet, and then stand back up for one rep.
7:52 @ 65lbs...and with my homegirl, AMiill
I know box squats are great for developing hip power by forcing you to start from a dead stop in the bottom. Bringing the feet up DID force me to sit on the box in a controlled (rather than touch-and-go) manner. LIFTING the feet created some instability and really required using the core to stabilize. I can easily see how the weight could get away from you if it were too heavy. Therefore, it may not have been the safest idea.
BUT at 65#, it was comfortable, and I liked how it forced a great deal of core strength.
Also, these combined with the GHD situps? My legs were jello after the last round.