Originally Posted by Hermes

Trainer workout HR, power and perceived effort is all over the map for me. In general, the trainer feels a lot harder for the same watts as the road. Theoretically, one could derate heart rate and power for trainer workouts due to higher heat and humidity and number of people in the room. MEA uses up all the oxygen and leaves me carbon dioxide to breathe. The more people in the room the more the concentration of CO2 goes up. Having said all that, I have a lot of experience on the trainer and know how to adjust my workouts to achieve goals.