Take on this intense ab challenge to strengthen and tone your core before the new year! Complete 200 mountain climbers, 100 ...

This ridiculously hard L-sit exercise works your entire body without moving a muscle. These are the progressions you can use to get strong enough to do it. Everyone likes a good challenge. That’s why ...

Training my abs is always tough, so I figured why not push it even further? I swapped out the usual sit-ups and Russian twists for a four-move dumbbell workout to really spice things up. I've been ...

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Beth Skwarecki is Lifehacker’s Senior Health Editor, and holds certifications as a personal trainer and weightlifting coach. She has been writing about health for over 10 years. Sprint interval ...

When most people think of a strong core or achieving abs, the first exercise that comes to mind is often sit-ups. While sit-ups have long been a go-to for strengthening the core, they're not always ...

Dr. Shields is a physical therapist with a background in English Literature and a passion for healthcare and education. She hopes to combine her clinical expertise with her love of writing, establish ...