What Mathematical Models Are Accurate for Prescribing Aerobic Exercise in Women with Fibromyalgia?

The well-known predictive equation "220 - age" and the FM model HRMax ("209 - 0.85 × age") showed agreement with the standard method (VT1), revealing that it is a precise model to calculate the exercise intensity in sedentary FM patients. However, proportional bias has been detected in all the mathematical models, with a higher heart rate obtained in CPET than obtained in the mathematical model. The chronotropic incompetence observed in people with FM (inability to increase heart rate with increasing exercise intensities) could explain why methods that tend to underestimate the HRmax in the general population fit better in this population.