Hey when I am usually doing cardio on a treadmill just walking at an incline, my heart rate is usually between 130-140 for 30 min straight. However, when I take for ex. 30mcg of clen before cardio my heart rate gets jacked up to like 155-170 beats per minute doing the same amount of work on the treadmill. My question is since the clen raises the heart rate to that new level, it obviously will burn more calories, but will hurt burn muscle as well, because the higher your heart rate is the more percentage of muscle to fat burning is higher than compared to a lower heart rate.