Today's workout focused on biceps and back with an added HIIT component and a core round to finish it off. This was my favorite core move of the day because it is a multitasker--it doesn't just challenge the core, it's also a great shoulder stabilization challenge.
If you try out this move, focus on keeping the rest of your body completely still and flat (no rocking hips or butt up in the air) and to make sure you have solid core activation to support your spine (think of pulling your belly button into your spine and tightening the corset of abdominal muscles).
Modifications: If it's too hard, try placing your feet wider for increased base of support. Still too hard? Drop down to your knees!