Rate Caps: Holding Rhythm So Pace Can Drift

The context

A rate cap is a deliberate ceiling on stroke rate. You hold the rhythm and let the pace do what it does.

The logic is sound in outline. Fix the rate, and every change you see on the monitor is a change in the work rather than a change in rhythm, so the split you are reading means something. Capping at 22, the only way to go faster is to push harder on each stroke, and the only way to hold the pace is to keep the stroke clean.

On an uncapped endurance row, a rising split can mean two different things: that you are getting faster, or that your rhythm is drifting and you are buying pace with a shorter stroke. The monitor cannot tell you which. Cap the rate and the second explanation is removed, leaving the first one standing on its own.

Where should the cap sit? Concept2's own bands are a better sanity check than most rules of thumb, and they are narrower than people assume. At 18-22 spm the flywheel has more time to slow down between strokes, so each stroke carries more load; that band is for practising technique, stroke sequence and rhythm, and long hard workouts at it are not recommended. At 24-28 spm the rate stays comfortable for steady-state work, and it is the band Concept2 recommends for longer workouts. At 30-36 spm you are into intervals and racing distances up to 2000 m. At 38 spm and above you are racing ([9] Concept2 2017). Most endurance work wants 24-28, or below it.

The core idea

Fix the rate and you have fixed force per stroke as a consequence. Cabrera's model is the clearest published account of the mechanics a cap acts on: its primary features are one-dimensional momentum balance, a point mass rower, infinitely stiff oars, and quadratic force-velocity relationships for the boat and the blade, and it predicts boat velocity well even when it is not fitted to velocity ([1] Cabrera 2006). A stroke rate enters that model as a quantity you can change without changing the rower, the boat or the blade.

What a cap does not do is make you more efficient, and this is where the drill is usually sold short. The common pitch is that a lower rate is a more economical rate, that holding the stroke longer keeps you economical and lets you do more at less cost. The study that tested it directly does not support that.

Seventeen well-trained female rowers rowed at 28, 34 and 40 spm at submaximal intensity with power transfer to the flywheel held constant, and gross efficiency did not differ significantly between the three rates ([3] Hofmijster 2009). The internal power losses the efficiency argument depends on were not there to find, and the secondary measure that rose with rate turned out to be unreliable for estimating them. So a capped rate is not a cheaper rate. Anyone rowing at 22 because it saves energy is rowing at 22 for a different reason, and it is worth being clear about which.

The earlier part of the same research group runs the other way. Across 20 to 36 spm, raising the rate increased the fraction of rower power that reaches the boat: blade losses fell as blade kinematics changed, and velocity-fluctuation losses fell as the impulse exchange between rower and boat grew ([2] Hofmijster 2007). Rate is not a tax on efficiency. Within the competitive range it redistributes power, and it redistributes favourably.

Together these give the position the rest of this guide rests on. Rate affects where your power goes, and does not visibly affect how much of it you get. A cap is a decision about reading and control, not about physiology, and what it buys is a session you can read honestly rather than a session that feels more efficient. If you cannot tell whether a session was aerobic from the monitor afterwards, you cannot adjust the next one.

The how-to

This is the part that has to be spelled out, because a cap you have not been told how to set is not a drill.

The cap is a number you hold, not a switch you flip. The performance monitor has no rate-cap setting. What it has is the number: stroke rate sits in the upper right corner of every workout display, in strokes per minute, and it updates on every stroke ([9] Concept2 2017). That readout is the whole instrument. A cap is what you decide the readout must not exceed.

Two ways to hold it. With no software, pick the number before you start and hold it by feel. The recovery is the dial, because the rate is a ratio of drive to recovery: if the number is climbing you are shortening the recovery, not adding drive. Concept2's own drill runs this in the opposite direction and is worth copying. Start at 28-30 spm, then every minute drop the rate two beats, 30, 28, 26, and try to hold the pace per 500 m. If you can hold the pace as the rate falls, the power is real; if the split drifts with it, you were buying pace with rhythm ([10] Concept2 2013).

With software you can be told. Concept2's ErgData app takes a target stroke rate for a workout and shows it next to your actual rate. The target field changes colour when you sit above or below it, dark blue when you are under the target and red when you are over it, and it is a reminder rather than a judge: the workout carries on if you miss it, with no penalty and no consequences ([12] Concept2 2022). You can set a different target for each interval of the workout.

What a capped stroke feels like. Lower the rate and the flywheel slows further between strokes, which takes more work to spin back up, so the recovery lengthens and the drive has to carry more ([11] Concept2 2020). The stroke feels heavier and slower, and the extra length in the recovery is where you will feel the cost. That is the physical signature of the cap, and it is the point of the exercise: at a capped rate you cannot hide behind a busy rhythm, so what is left has to come out of the legs. Low-rate work also breaks a stroke into its parts, because at 22 you have time to check your posture, your head position, your grip and your breathing rather than rowing past all four.

The cue: rows that look the same. A cap makes the stroke the only variable, which means a coach can watch the boat rather than the monitor. Put a rower in front and ask for a row that matches theirs: the catch arriving at the same time, the legs going before the arms, the handle coming in under the chest rather than out in front. At 22 the rower and the boat have to agree with each other, and a stroke that is only held together by hurrying shows up in the seat and the back, not in the split.

A worked session. Ten minutes of warm-up, uncapped, at 24-26 spm and an easy effort, and let the split settle before you cap anything. The first two minutes at a new rate always look worse than they are.

Then 20 minutes at 22 spm. Watch the split, not the rate. It will start at your normal 2:00 and drift — 2:03, 2:05, 2:07 — if your rate has been drifting upward through the session without you noticing. If it holds at 2:00 and you are still working, that is the finding: the split you thought you had was never there. Expect the cap to feel heavy for the first three minutes and then settle.

Then 4 x 4 minutes at 24 spm with 2 minutes easy at 20 between. Each interval should start close to the same split and drift a little further than the one before it, and that drift is the reason to do the set: four intervals that fall away by half a second each time tell you that the ceiling of your steady-state work sits below the split you are reading. Write down the two numbers that matter before you stop: the split at the start of the capped piece and the split at the end, plus the rate you actually averaged. If the rate you averaged is above your cap, the cap was not held and the piece tells you nothing.

The trade-offs

Three limits, then the distinction that matters most.

A cap does not control volume. It constrains rhythm, not how long you row or how many strokes you take. A capped row at a high split is still hard work, because intensity is set by how hard you pull on the drive, not by the rate you pull it at ([10] Concept2 2013).

A cap does not control the physiological cost of the piece. Cardiovascular drift is the process by which the same external output costs progressively more cardiovascular output over time ([4] Coyle 2001). Holding the rate down does not stop that, it makes it visible. A split that climbs while the rate holds is fatigue or a form change, and chasing it is the main way a long session stops being aerobic.

Managing intensity distribution is what a cap is for. Seiler's account of where training time should sit ([5] Seiler 2010), Stöggl and Sperlich's nine-week, four-way comparison of distribution strategies, in which the polarized group came out ahead on VO2peak and time to exhaustion while also logging more training hours than the threshold and interval groups ([6] Stöggl 2014), and Ingham's rowing-specific comparison of low- versus mixed-intensity training ([7] Ingham 2008) all say the same thing: do not spend threshold sessions on ordinary days. None of those papers is about stroke rate. They are about where the intensity goes, which is the thing a cap is actually good at enforcing.

Capping rate is not capping intensity. A row at 22 that drifts from 2:10 to 1:50 is not aerobic, whatever the stroke rate says. A cap helps when the session is meant to be aerobic and the cap is what keeps it there. A cap gets in the way when the session is meant to be hard, and it will happily let a threshold piece run for an hour at a rate nobody could row in a race.

When not to use it. Drop the cap for a race piece and for a genuine threshold session. In both, the rate is a consequence of the work you are doing, and constraining it removes the thing you are trying to measure. And if the session you are protecting is the one before a key race, the reference is taper dose-response rather than a rate ceiling: two weeks of tapering, with training volume cut by 41 to 60 per cent and intensity and frequency left alone ([8] Bosquet 2007).

What to do tomorrow

Four things, in order.

1. Pick the cap from the band, not from the rate you happened to row last time. 24 spm for a long aerobic row, 20 or 22 for a technique block, and write the number on the machine before you start.
2. Decide how you will hold it before you start. Either the number on the display, or a target rate in the app so it colours when you cross it. Doing both is fine, but pick one to write down.
3. Run 20 minutes under the cap and write down two numbers: the split at the start and the split at the end, plus the rate you actually averaged. Three numbers, one session.
4. Decide in advance what the split is allowed to do. If it climbs, that is fatigue and you stop chasing it. If it falls, that is the cap working and the piece was easier than you thought.