Post-static dyskineisa is a bit of a mouthful, but it is that worse pain under the heel when you get up from rest, especially in the morning. Post-static refers to the after resting and the dyskinesia refers to the pain. It is a characteristic symptom of plantar fasciitis, but can also be due to other less common problems. Typically the pain can be quite painful and starts to ease after a number of steps. There are a number of theories about what causes the post-static dyskinesia.
What can you do to lesson the pain in the morning? Firstly, get some treatment for whatever may be causing the pain, so that it will get better over time. Secondly, what you can do before you get up out of bed or out of a chair after rest is to stretch the foot, especially dorsiflexion. To do this pull the front of the foot up towards you. Move it around; do it several times. Sometimes just rubbing the bottom of the heel with your hand to give some sensory stimulation to the nervous system can ease that first step pain.
Those who wear the night splints for plantar fasciitis report that they have less post-static dyskinesia or first step pain in the morning after a nights rest wearing it.