Aerobic base

Aerobic base tracks one thing: how much work your steady rowing buys for each heartbeat. The score is watts per beat. The story is the pace you hold at your steady heart rate. Both read off the same line, so they can never disagree.

Which pieces countCopy Anchor Link

Only steady pieces feed the trend. A piece counts when all of these hold:

• Heart rate covers at least 80% of the piece. Without a strap or a health-app series, there is nothing to measure.
• At least 30 minutes of work. Rest is left out. The 30 minutes can be split across intervals: a 3 × 4,000m at UT2 counts.
• At least 80% of the work is in Recovery or UT2, by time in your heart-rate zones. A test piece or a hard session spends too long higher up to count.
• The capture is whole. A PM5 capture that lost its data stream partway through is left out.

Each machine is its own trend. A RowErg and a SkiErg turn the same heartbeat into different watts, so they never share a line.

Watts per beatCopy Anchor Link

Watts per beat = average watts ÷ average heart rate, over the work strokes of one piece. A stroke counts only when it carries both a pace and a heart rate. Watts come from each stroke's pace, the same way the monitor converts them.

One piece is noisy. Heat, sleep and hydration all move heart rate. So the line is smoothed: each point is the mean of every steady piece within 10.5 days either side of it, a 21-day window. The window is in days, not pieces, so a week with five sessions does not outweigh a week with two.

A trend appears after 6 steady pieces spanning at least 21 days. Before that, the reading counts what it has, for example 4 of 6 steady pieces. The change is the percent difference between the first and last smoothed points in the window. A window that cannot meet the same bar on its own pieces says so, rather than borrowing points from outside it.

The reference heart rateCopy Anchor Link

The story is told at the top of your UT2 heart-rate zone: by default 72% of your max heart rate, rounded. With custom zones, it is the top of your own UT2 band. With no max heart rate in Settings, there is no reference and the trend cannot show.

Pace at the reference heart rateCopy Anchor Link

Watts at the reference = watts per beat × reference heart rate. Ergon turns those watts into a pace with the machine's own relation: per 500m on the RowErg and SkiErg, per 1,000m on the BikeErg. The pace at UT2 chart is the same smoothed line, shown in pace.

If watts per beat goes up, the same heart rate buys more speed. That is the aerobic base growing.

The other readingsCopy Anchor Link

• Steady m, season: meters in your UT2 power zone this season. The season is Concept2's, 1 May to 30 April, unless Settings uses the calendar year.
• UT2 watts: the top of your UT2 power zone, 60% of your threshold watts by default.
• VO₂max: the latest estimate from your health app, when it has at least two readings.

No heart rateCopy Anchor Link

When none of your pieces on the machine carry heart rate, the page reads steady meters instead. The headline is this season's UT2 meters. Beneath it: your average pace in that zone and the weeks with any UT2 work. The last reading compares with the same stretch of last season. The chart shows steady meters a week.

Honest limitsCopy Anchor Link

• It needs a strap, worn often. Steady pieces without heart rate do not count.
• Indoor drift is normal. Heart rate creeps up across a long erg piece with no airflow. Ergon does not reject a piece for it. The smoothing absorbs it.
• A wrong max heart rate moves everything. The zones decide which pieces count, and the reference decides the pace. Set it from a real test if you have one.