India, Jan. 30 -- A sharp side stitch, aching muscles or a sudden cramp can derail even the most dedicated workout - but most of these annoyances are harmless and easy to manage. Berlin (dpa) - Anyone who regularly does sport knows that aches and pains come with the territory. Troublesome though they may be, they're usually quite harmless. Two experts explain what recreational athletes can do to avoid them, and what measures to take when they occur. 1. Side stitch: When your diaphragm pipes up It's not fully clear what causes a side stitch - a sharp pain in your side under the ribcage - during athletic activity. The medical term for it is exercise-related transient abdominal pain (ETAP). "Recent studies indicate it involves the diaphragm," ...