This 9-minute ab workout uses one piece of equipment to build a stronger, more functional core

Carve out just nine minutes a day, five to six times a week, and watch how your core transforms.
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I tried the ‘hardest’ abs workout on YouTube — here’s what happened

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 ...