If exercise is nothing new for you, it's more likely a dry skin
. Since you didn’t mention any other symptoms, it could be that dry skin is the culprit. Are you walking outside or inside? Often, dry weather conditions can cause or exacerbate dry skin. If this is the case, using lotion, investing in a humidifier, and staying hydrated can all help combat dry skin.
Skin irritation. Have you switched detergents, started using a new lotion, or are you using a new soap?