Question: I’m 32 and been riding for 16 years, but I’ve just begun using a heart monitor. Last winter, when I was training only three or four times per week, I checked my max HR on a hill and it was 189 bpm. My average for a time-trial effort was 170-175 bpm.
Now, after several months of increased training, my maximum is down to 175 and my TT average has fallen to 165. When I go past 165-170, I often flag and my legs sting, although last winter I could ride through this. I had a virus that hung on in the spring. Do you think that’s what’s causing this? — Nick K.
Coach Fred Matheny Replies: It isn’t unusual for increases in fitness to cause decreases in maximum and lactate threshold (LT) heart rates.
When you’re not as fit, the heart beats faster but doesn’t pump as much blood. Then, after effective training, the heart’s top end decreases while the stroke volume (the amount of blood pumped per beat) increases.
Another reason for your lower heart rate might simply be fatigue. If your legs are too tired to pedal with intensity, they won’t be able to drive up your heart rate. Heart rate follows muscular exertion. If your muscles aren’t up to the task, your heart rate numbers will be lower.
That spring virus could be playing a role, too. A viral infection can affect the heart. It sounds like you’re simply becoming more fit, but it would be wise to rule out any medical condition.