The article tries to spin it in a positive light - i.e. that releasing adrenaline in the brain is beneficial. However we care about the direct message itself - adrenaline/noradrenaline are stress hormones and lactic acid triggers their release in the brain. This is likely harmful if experienced chronically.
http://www.eurekalert.org/pub_releases/ ... 021014.php
http://www.eurekalert.org/pub_releases/ ... 021014.php