<p>I don't think there are classes, but you can always join a club and play club sports. (Think of it as a non-for-credit class ;) )</p>
<p>There is however a workout center and a lot of the non-freshman dorms have work out rooms. There are tennis courts too.</p>
<p>Oh and then there is this, classes that are for credit and may resemble PE. <a href="http://www.jhu.edu/registrar/sched_cr/military.html%5B/url%5D">http://www.jhu.edu/registrar/sched_cr/military.html</a> (ROTC related I believe.)</p>