A zone scheme over a value axis: ascending edges (length = nZones + 1, the
last a large sentinel for the open top) and the labels per zone (Z1 first).
The axis is bpm for HR and m/s for pace (we bucket speed, not pace, so a
stop doesn't blow the reciprocal up — Z1 = slowest). Power reuses the same
shape over watts.
A zone scheme over a value axis: ascending
edges(length = nZones + 1, the last a large sentinel for the open top) and thelabelsper zone (Z1 first). The axis is bpm for HR and m/s for pace (we bucket speed, not pace, so a stop doesn't blow the reciprocal up — Z1 = slowest). Power reuses the same shape over watts.