404. That’s an error.

The requested URL /bookmarks/mark?op=add&bkmk=https%3A//bjsm.bmj.com/content/43/10/775&title=Exercising%20with%20reserve%3A%20exercise%20regulation%20by%20perceived%20exertion%20in%20relation%20to%20duration%20of%20exercise%20and%20knowledge%20of%20endpoint was not found on this server. That’s all we know.