Contracting Muscles (VIDEO) Duke University This video is under embargo. Please login to access this video. Caption Lab-grown muscle bundles fluoresce when their calcium levels spike - a proxy for measuring their strength. The muscle bundles that were electrically stimulated to approximate exercise during inflammation (right) flash just as robustly as normal muscle bundles (left) and much more brightly than unexercised muscles after chronic inflammation (middle). Credit Zhaowei Chen, Duke University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.