Ready for a challenge? Grab a medicine ball and try the juggling plank, which might just be the hardest upper body exercise you'll do all week. There’s no easy plank. That’s a fact. Whether you’re on ...

GUINNESS RECORD HOLDER KAI SANDMEYER, SAYING:"My name is Kai Sandmeyer, I currently hold the record in "longest hula hooping in abdominal plank position" with six minutes 34 seconds." "The hardest ...

Abs workouts do not need to be long to be very hard, but even so when a video popped up on my YouTube feed claiming to be the "hardest abs workout ever" and it was only 10 minutes long, I was suitably ...