Will Smith's daughter Willow isn't the only one whipping her hair back and forth. Runners and fitness enthusiasts with long locks pulled back in ponytails are also thrashing their tresses.

On TikTok, a celebrity hairstylist shared a video revealing why ponytails can be damaging to wear during workouts.

"If you exercise and also care about your hair, you are going to want to listen to this," Tom Smith, who shares beauty content as @tomsmithhd on TikTok, begins the clip.

"Just been in the park this morning and saw someone jogging. As she was running, her hair was swishing from side to side, and I thought, 'God, that's like whiplash for your hair,'" Smith explains.

"If you go for a run and you have your hair loose whipping back and forth, it's an absolute recipe for split ends and really dry friction burn on the ends of your hair," Smith continues.

Instead of a ponytail, Smith recommends some other styles to try: "Make sure that you wrap it, maybe braid it into a neat little bun, keep it all tightly tucked away so that it's not moving as you run."

Watch below:

In the comments section, many viewers admitted they had never thought about how their workouts could affect their hair health.

"Hair is so delicate you can't do anything without damaging it. I give up," one TikTok user commented.

"Thanks, Tom! Never considered this before but will go back to a bun!" another wrote.

"No way! I was just on a run and had my hair like that. Now I'm feeling self-conscious," someone else shared.

Others took a comical approach to Smith's advice.

"Better be safe and not run at all," one person suggested.

"So are you saying I have to drop exercising to have healthy hair? DONE BESTIE," another joked.

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