This is unique to those areas with a cold winter.  The ground hardens up and becomes much harder on the bottom of the feet.  Thus when kids where their cleats out for the first lacrosse or soccer practice, they don’t sink into the ground but rather pound on top, transmitting extra pressure into the heel and ball of the foot.  Another reason is that most of us in cold climates are naturally more sedentary in the winter. This is true for kids too! Thus as they go back to activity in the spring their achilles or heel cord has tightened up. This also puts increased tension on the heel growth plate making them more at risk for inflammation in the area. 

Dr. Misty McNeill
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D.P.M. - Founder of Prairie Path Foot and Ankle Clinic