Physiological and subjective measures of exercise intensity cycling at 55% and 85% of functional threshold power: Findings from a randomised crossover trial.

Functional threshold power (FTP) is a popular power-based training method widely used by cyclists. However, the relationship between FTP and traditional variables that underpin endurance performance are incompletely understood. We investigated the influence of cycling at 55% and 85% of FTP on traditional measures of exercise intensity. Twelve healthy males completed questionnaires, body composition assessment by dual X-ray absorptiometry and graded exercise test to determine maximum oxygen consumption and FTP. Participants were then randomised and asked to complete two 30-min bouts of cycling at either 55% or 85% of FTP. Oxygen consumption, heart rate, blood lactate and rating of perceived exertion (RPE) were recorded at baseline, after 15 and 30 mins at each workload. Participants demonstrated statistically significant increases in physiological and subjective measures within and between exercise trials (all p < .05). Overall, the results indicated that cycling at 55% and 85% of FTP elicits changes in physiological and subjective measures of exercise intensity equivalent to moderate and vigorous intensity training, with small discrepancies between physiological and subjective measures. Therefore, cyclists should use heart rate and RPE with FTP-derived training zones for demarcating exercise intensity, as FTP alone seems to underestimate the physiological and psychological demands at workloads ≥85% of FTP.