Since you left the sentence unfinished, we'll have to guess what is causing your bad runs. My guess is the bottom of your feet. In that case, check your shoes. There are three types of shoes, and you may have the wrong type. Your shoes might need to be changed. Get new shoes every 300-500 miles. Be sure you have good quality shoes, not cheap "mall store" shoes. Go to a reputable running store for your shoes. Shoes are one of the common causes of running injuries....
Posted by emmasandy