What Is the Watta Effort Score?

By the Watta Team · Updated 9 October 2026

The Watta Effort Score converts your Concept2 PM5 data into a single 0-100 number that tells you how hard a rowing workout actually was. It weights cardiac load, work output, pacing, and economy so you can compare sessions fairly — whether it was a 2K test or a 45-minute steady state row.

What Is the Effort Score?

The Effort Score is Watta's signature metric. It is a 0-100 rating calculated from four components: Cardiac Load (up to 40 points) measures how hard your heart worked from your average heart rate as a fraction of heart rate reserve. Work Output (up to 35 points) captures watts and duration. Pacing (up to 15 points) rewards consistent splits across intervals and a negative split. Economy (up to 10 points) looks at watts per stroke. Together, these four factors create a score that reflects the true physiological cost of a workout.

Why a Single Score Matters

Rowers produce a huge amount of data every session: split, watts, stroke rate, heart rate, distance, and time. Comparing two workouts is hard because the numbers measure different things. A hard 2K produces high watts and heart rate but lasts only 6-8 minutes. A long steady state row produces lower watts but accumulates cardiac load over 60 minutes. The Effort Score normalises these differences so you can compare any two sessions directly.

Cardiac Load — up to 40 Points

Cardiac Load takes your average heart rate for the piece as a fraction of heart rate reserve (the Karvonen method, from the resting and max heart rate in your profile) and scales it non-linearly, so 90% of reserve counts far more than 70%, with a small age credit. It is weighted heavily because heart rate is the most direct signal of physiological strain on the erg. Without heart rate, Watta estimates it conservatively from power and duration, capped at 28 points.

Work Output — up to 35 Points

Work Output compares your average watts with a baseline of 150 W for a 75 kg rower, scaled for your body weight with the Concept2 0.222 exponent, and multiplies by a logarithmic duration factor. Faster paces and longer durations both increase it, with diminishing returns on duration. Watts come from the monitor when it shows them, otherwise from pace with the Concept2 formula.

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Pacing — up to 15 Points

Pacing measures how evenly you distributed effort across the intervals of a piece (coefficient of variation of the splits) and adds a 3-point bonus for a negative split. A single continuous piece with no interval data scores a fixed 10. This encourages race discipline and efficient energy use, especially for tests and time trials.

Economy — up to 10 Points

Economy looks at watts per stroke. Very efficient low-rate rowing (over 8 W per stroke) scores 6, a good balance (over 6 W per stroke) scores 8, and high-rate work scores 10 — the component gives extra effort credit to high-rate rowing, which is more cardiovascularly demanding, rather than rewarding efficiency for its own sake. Without a stroke rate it scores 5.

How to Use Your Effort Score

Use the Effort Score to compare workouts across different types and durations. A 75 on a steady state day and a 75 on a sprint day represent similar total physiological cost. Track your average Effort Score over a week to manage load, and compare scores at the same pace over months to see fitness improvements. If your Effort Score is dropping at the same split, you are getting fitter.

Tips

+Enter accurate resting and max heart rate in Watta for the most meaningful Cardiac Load score.
+Compare Effort Scores for similar workout types before comparing across test pieces and steady state.
+A dropping Effort Score at the same pace means improved aerobic fitness.
+Use Effort Score to manage weekly training load and avoid overreaching.
+Pair Effort Score with heart rate zone analysis to understand why a workout felt hard or easy.

Frequently Asked Questions

What is a good Effort Score?

It depends on the workout. A steady state session might score 40-60, a threshold piece 60-80, and a 2K test 80-95. The score is most useful when compared to similar workouts over time.

How is Effort Score calculated?

Effort Score adds Cardiac Load (up to 40 points), Work Output (up to 35), Pacing (up to 15) and Economy (up to 10). It uses average heart rate against heart rate reserve, watts, duration, interval splits and stroke rate from your Concept2 workout.

Can I compare Effort Scores across different workouts?

Yes. The score is designed to normalise differences in duration and intensity. A 60-minute steady state row and a 6-minute 2K test can produce similar scores if their total physiological costs are similar.

Does Effort Score work without heart rate?

Yes. Without heart rate, Cardiac Load is estimated conservatively from power and duration and capped at 28 of its 40 points, so the same piece scores lower than it would with a strap paired to the PM5. Work Output, Pacing and Economy are unaffected.

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