17 year old long distance runner. District champ, state qualifier... last competitive run ; half way into run, tunnel vision , arms and legs numb, tightness in chest , collapsed at finish line. Unable to walk without assistance, no SOB, H/R 94 reg. Next 3 days muscle soreness, exhaustion. Has had lab work, came back normal. Daily workout since, 400m, 800m, sprints, no problems. attempted 1 mile could not complete. After 3 laps arms started to go numb.