Yes. The GRIND was designed with Density points to help increase blood flow to the area you are rolling. The marks indicate there has been an increase in blood flow. But, if for any reason the marks last for longer than 1-2 days or if they become tender or bruised reduce the frequency of use until the marks have diminished. If the marks continue, then reduce the amount of pressure on the GRIND while rolling. Additionally, be aware of your body’s hydration level – this can affect the marks left on your body after using our products.