Medically reviewed by Amy Kwan, PT Key Takeaways Isometric exercises involve contracting muscles without any additional ...

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. While many types of ...

Stand upright with both arms out in front of you, bent at a 90 degree angle. Lock your hands together and squeeze as hard as you can. Hold the contraction for 15-30 seconds then relax. Expert tips: ...