Abstract: Provided is a computer-implemented method of determining exercise parameters, such as heart rate thresholds, endurance, maximum heart rate and lactate threshold. The method comprises fitting a continuous curve to heart rate data obtained over time from the onset of exercise, the curve comprising a plurality of components that meet at transition points that join the components. The exercise parameters are obtained from the curve fitting of the heart rate data. Also provided is a system for determining exercise parameters, in particular a computer-implemented system that determines exercise parameters using the disclosed method.