Based on my personal experience as a heavy user of multiple wearable fitness tracker devices over several years I recommend removing LOINC code 55422-0 (Heart rate Encounter maximum) from the profiles, value sets, and examples. I think that concept code was intended for use with medical devices in a clinical setting but consumer devices such as smart watches, rings, and heart rate monitor chest straps aren't accurate enough for maximum readings to be clinically meaningful. I have personally experienced several spurious readings during exercise activities that were significantly higher than my actual maximum heart rate.

And even if a patient really does hit a particular peak heart rate at some point during an activity that usually isn't clinically significant. A single peak value isn't meaningful without other context such as tested maximum heart rate, lactate thresholds (LT1 / LT2), and time spent at or near the peak.

Instead consider using LOINC code 55425-3 (Heart rate unspecified time mean by Pedometer). With a typical activity lasting at least a few minutes the mean heart rate will usually be fairly accurate even with a few outlier samples.