Control Metric

Definition

“Control metric” is the primary measure around which a training session is built. It defines how the target intensity is prescribed, how it is controlled during the session, and how the session is evaluated afterwards.

Which metric is suitable depends on the sport and the training focus. The control metric is also the basis for derived load measures such as Intensity Factor and Training Stress Score.

Why it matters

Without a defined control metric, “easy” or “hard” cannot be verified. Only the metric makes it possible to hit a zone, compare a session with an earlier one, and add up load over weeks.

The choice also shapes the outcome. Power responds instantly and is independent of wind or gradient; heart rate lags by one to two minutes and is affected by heat, sleep, and caffeine. Pace in running is only meaningful on flat ground; off-road it takes Normalized Graded Pace.

Depending on the focus, a secondary metric can move to the foreground: heart rate when cardiovascular work is the point, speed for race-specific sessions on a known course.

How obseed measures it

obseed assigns each session a control metric based on its sport profile and derives Intensity Factor (IF) and TSS from it. The zone boundaries for the control metric come from metabolic testing: power and heart rate at the ventilatory thresholds VT1 and VT2, plus the corresponding treadmill pace.

An estimate such as FTP from a 20-minute test would shift the zones by several percent, so obseed does not use it as a reference. If no primary metric is available for a session, for instance because the power meter failed, obseed falls back to heart rate and marks the session accordingly.

Example

A cyclist plans a threshold session of 3 × 12 minutes. His VT2 from spiroergometry is 280 W and 168 bpm.

Power was on target. That heart rate drifted above VT2 in the third interval points to cardiovascular drift in warm conditions, not to a failed session. Had heart rate been the control metric, he would have reduced power in the third interval and cut the training stimulus short.