Palpitation is an awareness of the abnormal beating of the heart. It may occur in people with or without heart problems. Heart palpitations when lying down is not a common occurrence and can be caused by various factors.
Flat feet occur when the normal foot arches have partially or completely collapsed. When the foot is put to the ground the inner or middle side of the foot comes down to the floor rather than remaining raised. This can cause the whole foot to roll inwards (this is called over-pronation).
Although pronation is a natural movement of the foot, the size of the runner's arch can affect its ability to roll, causing either supination (underpronation) or overpronation. If you have a normal arch, you're likely a normal pronator, meaning you'll do best in a stability shoe that offers moderate pronation control.