Dear Fit,
I went to a four-day cleansing yoga intensive over the weekend. It was great. I felt so relaxed by the end of the retreat. Come Monday, though, back at my desk, a muscle in my back started twitching, just below my rib cage. I will admit it was a rough adjustment after four days on a yoga mat. The muscle kept twitching off and on all day; there was no pain but it was really annoying. What would cause this to happen? Did I stretch it too hard at my retreat?
— All Twitched Out

The yoga retreat sounds lovely, but I feel you on the back twitch. To see what I think, just read more.

Muscle twitches like yours are small muscle contractions in a specific area, or they can be an uncontrollable twitching of a group of muscles served by a single nerve fiber. There are a few factors that might have contributed to your back twitching: stress, caffeine, and diet. Twitches can be brought on by stress or anxiety; while this more commonly happens around the eye, it can happen to muscles in other areas too. Coming back to work can be stressful, especially after taking time off since work can pile up. If you have dealt with the shock of being desk-bound by drinking an extra cup of joe, the additional caffeine could lead to muscle twitches as well. A twitching muscle is also a symptom of a diet low in magnesium. If you were doing lots of athletic yoga in a hot environment, excessive sweating could lead to loss of magnesium. Consider adding chard and spinach to your diet, since both are high in the mineral. Or, try sipping a sports drink that contains magnesium. My favorite is Nuun — you drop a tablet into your water bottle.

Lastly, muscle twitching can occur post-workout, generally after strenuous weight training or cardio sessions. If you were doing rigorous yoga and lots of it, this might explain the twitch.