hi, i am training to run a marathon for the first time. This is the second time I have consistently run in my life and I am running for greater distances this time. Also I have not yet bought a pair of running shoes but am running on an indoor track in basketball shoes that I used during my last running period to no ill effect. The problem is that I am feeling a slight pain at my right upper thigh whenever that leg makes an upward bend motion at the joint connecting the thigh to torso. Does anyone know what could be causing this? Like I said, I am runnning on an indoor track with bball shoes but I did this last time without any such pain or discomfort. Could it be that I am running for longer distances?