Dangerous heat and humidity can be hard on athletes during practice.
A high school in Shelbyville is using a new product to prevent their players from getting heat stroke.
It's a sticker for the skin called the ionX Body Temperature Alert Patch, otherwise known as hot dots.
Officials say the waterproof black dot is stuck on a vein on the arm or neck, out of direct sunlight.
It measures the body's core temperature and when it turns yellow, that means danger and time to take a break until the color darkens again.
About two years ago, a football player at a Louisville high school died after a practice in the heat.
The alert patches were donated to the school and cost about 50 cents a piece and are available online, at www.ionxalert.com .