Which is a better way to jumprope for a cardiac exercise: jump rope on my toes or keep my feet flat?

Balls of your feet. You use the calves more and get a better workout using the balls of your feet. If you try to jump rope flat footed, it can put too much of a pounding on the heel. This can lead to plantar fascitis, calcaneal stress fracture, or bruising of the calcaneus(heel). The key to jumping rope is to wear good supportive shoes that can absorb the pounding from jumping rope.
Best Way to Jump. Better to land on the ball of your feet. Keeping your heels up will allow more mobility & speed. Also landing on your toes allows some downward give whereas landing on your heels has no give & can lead to injury. Dr george tsatsos anklenfootcenters.Com.