Have you ever noticed that your voice sounds and feels different after running, aerobics, or other cardiovascular exercise? Studies have shown that using the voice immediately after physical activity requires increased laryngeal effort. In the studies done, aerobics instructors used their voices after an intense workout. There was a noticeable increase in the closure forces of the vocal folds (Phonation Threshold Pressure) during this time. The aerobics instructors also experienced an increase in perceived vocal effort. For most of us, this suggests that we should take a break between full-body exercise and our vocal workout. It's very good for your singing that you be in great cardiovascular and aerobic shape. Just make sure that you avoid doing things back-to-back if you're bothered by this tendency! Or, sing first and then do your workout second. Run. Rest. Sing!