I mountain bike race in the summer, cyclocross race in the fall, and nordic race in the winter. I’ve noticed that while my perception of effort is very similar across these disciplines (really flipping hard), my heart rate average and peak are significantly lower in a nordic race than in either a cross or mtb race. For instance, in a roughly one-hour mtb race, my heart rate will typically average around 154 and I’ll see a maximum of only a few beats below my peak of 167. For a 45 minute cyclocross rate, I’ll see slightly higher averages and maximum. For a 20 minute short track race, I saw an average of 161 and a maximum of 167. For a 20 minute nordic race, I’m seeing an average of 150 to 153 and a maximum of about 161 to 163. For a recent 45 minute nordic race, I saw an average of 152 and maximum of 161.
Since I’m recruiting a lot more muscle mass for nordic, this relationship to heart rate seems reversed, so I’m assuming it has to do with my being better trained for cycling than for nordic (riding season is longer than ski season), but I don’t really know and my question is: should I expect to see my heart rate for nordic come more in line with my cycling heart rate as the nordic season progresses, or is there simply some physiological phenomenon at work. My approach to training and rough weekly volumes is pretty similar.