If the shoes on your feet or the pairs in your closet have their front tips curved upward, it's because they have toe springs.
The toe spring puts the foot in a perpetually flexed position.
It's designed to make walking and running more comfortable and energetically efficient.
But Business Insider reports a new study shows toe springs may weaken the foot muscles over time, which could contribute to injuries like plantar fasciitis.
That could lead to plantar fasciitis.