Johansson L, et al. - Researchers sought to present specific reference values for cardiorespiratory fitness (CRF) in children with obesity and to examine secular trends of CRF in the studied population. They estimate CRF the maximal oxygen uptake (VO2 max), with the Åstrand-Rhyming submaximal bicycle test, in 705 Swedish children with obesity according to the International Obesity Task Force (IOTF). In comparison with normal-weight standards, children had low CRF, however, in children with obesity, there was a marked variability of CRF, which was feasible to quantify with the developed obesity specific CRF reference values. It was found that these were the first obesity specific reference values of CRF in children enabling clinical evaluation in childhood obesity treatment. Moreover, in the last decades, CRF in children with obesity had declined, and it was also shown that within this vulnerable group physical activity has gone down.