FEATS OF STRENGTH
200 Points
Why are they called Jack Knives? Yeah – no idea. But let’s get this over with so we don’t have to worry about it! Make sure you keep your butt level and don’t let it sag. This is an ab exercise not a lower back exercise!
Why are they called Jack Knives? Yeah – no idea. But let’s get this over with so we don’t have to worry about it! Make sure you keep your butt level and don’t let it sag. This is an ab exercise not a lower back exercise!