However, physical activity levels were negatively associated with circulating Irisin (r=−0.22, p=0.001) in groups of anorexic, obese and healthy women36, while they were positively associated with circulating Irisin in both COPD patients (r=0.83, p<0.01) and healthy individuals (r=0.79, p<0.001)34. This evidence concerns the gene FNDC5 and chronic obstructive pulmonary disease.