Scientists in the US have found that a feel-good exercise hormone called irisin DOES exist. Previously thought to be a myth but new research team from Dana-Farber Cancer Institute used mass spectrometry to look for irisin in blood samples of individuals after exercise. The form of mass spectrometry used in the new study was far more accurate and reliable in measuring irisin. Found that these people had released the exercise hormone from their body, which activates fat cells to increase energy turn over