In the fitness class Jessie Syfko created for a nationwide gym chain, exercisers wear weighted vests that add a challenge to their workouts.

“People start to realize how good it feels to work just a little bit harder and a little bit smarter” without actually changing what they’re doing, said Syfko, senior vice president for Life Time gyms.

Weighted vests are increasingly showing up in fitness classes and on jogging tracks, touted by social media influencers as a way to keep bones healthy, improve performance and even accelerate weight loss. They are exactly what they sound like – vests that add resistance to the torso through pockets with removable weights.

But there's a lack of robust research on their benefits, experts say, so it's unclear how much of the hype is justified. And some

See Full Page