This is the best low-impact way for beginners to build strength—and you don't need any equipment to do it

Two women holding plank position in fitness studio. They are both smiling.

You may not have come across the term isometric training, but if you've ever done a plank, then you've done an isometric exercise. "Isometric training involves the static contraction of a muscle, without any sort of movement of your joints—you're holding your muscles still against some form of resistance," says personal trainer Rowan Clift.

Isometric holds can be a useful tool to challenge your muscles in a new way. Improvement is easily measured because you can hold the position for longer. And because there’s no movement, there’s no impact, and much less chance of injury.