Does training change my maximal heart rate?

Zavorsky questions the general consensus that maximal heart rate is "relatively unaltered regardless of training status".

While aerobic training is known to lower submaximal heart rate at a given workload, several studies, he writes, report HRmax reduced after regular aerobic exercise in sedentary adults and endurance athletes and raised again when training stops, and tapering or detraining can increase it.

Across studies of training, tapering and detraining, the changes in VO2max and in HRmax correlated highly (r = −0.76, p < 0.0001, n = 314): as VO2max rises HRmax tends to fall, and when detraining sets in HRmax tends to rise. Effect sizes from several studies were −0.48 for training and +0.54 for detraining, a moderate effect, so that HRmax "can be altered by 3 to 7%".

Proposed mechanisms are autonomic (plasma volume expansion, enhanced baroreflex function) and intrinsic (changed electrophysiology of the sinoatrial node, fewer and less dense beta-adrenergic receptors).

Because research on the question is limited, the author asks for cautious interpretation until better studies confirm it, and suggests monitoring HRmax directly through the year, perhaps every 3 to 6 weeks.

Our reading: the base's other within-person source is detraining in endurance athletes, where maximal heart rate rose 2-9 beats per minute once training stopped (REF-1133, full text), the direction this review reports; it does not contradict REF-1082, where HRmax did not differ with habitual activity between people — a cross-sectional comparison of different people, not the same person before and after training — but it means a measured HRmax is a moving target, by a few beats, in a big training change.