У вашего броузера проблема в совместимости с HTML5
Set-Up - Reach up and with a closed grip grab the pull up bar (hands outside the shoulders) - Protect the shoulder cavity by slightly depressing the shoulders (this will activate the lats) - Tight mid-section Execution - Pull yourself up so that the chin is higher than the bar - Lower yourself down with control but NOT slowly so that the arms are completely locked out at the bottom