Erg Training Zones: UT2, UT1, AT and How to Set Them From a 2k

A 2k result is the one number every other erg session hangs off, and the zone model turns it into five bands, each with a split, a stroke rate and a job. Most rowers who train without a coach never set the bands. They pull every piece at the same medium-hard effort and the monitor looks busy for months. The 2k stops moving.

The five zones and what each one trains

The names come from the system British Rowing uses in its club programmes: UT2, UT1, AT, TR and AN, with UT standing for utilisation training, the two aerobic bands where you spend most of the year. AT is anaerobic threshold. TR is transport, the VO2max band. AN is anaerobic, the sprint band. Rowing research sorts the same work by blood lactate: below 2 mmol/L, 2 to 4, and above 4, the bands a diary study of 36 junior world-class German rowers used.

• UT2 is aerobic base. Long, low-rate rows where you could hold a conversation, lactate under 2 mmol/L, and British Rowing puts it at 65-75% of max heart rate, with UT1 at 75-80%. This is where the aerobic engine gets built. It is also the zone most people row too fast.
• UT1 is aerobic power. Firm steady state, breathing deliberate, a sentence still comes out and lactate sits between 2 and about 3 mmol/L. Useful in small doses. Toxic as a default.
• AT is threshold. The hardest pace you can hold for 20-30 minutes without lactate running away, around 4 mmol/L on most tables, and the band that lifts the middle 1000m of a 2k.
• TR is VO2max. Intervals of 3-8 minutes, at or a touch slower than 2k pace. This raises the ceiling. The other zones fill it in.
• AN is anaerobic. Sprints under 90 seconds, faster than 2k pace, full recovery between. Small volume, high cost.

Two of these bands do most of the work, UT2 building the engine and TR raising its ceiling. The rest are seasoning.

Why a 2k, and why the math runs through watts

Lactate testing costs money. A true max heart rate is hard to find alone. A 2k is free and repeatable, so it is the anchor coaches build zones from. If you have not raced one, the 2k pacing guide covers how to get an honest number out of it, and the 2k predictor estimates one from a 500m, 1k, 5k, 6k or 10k piece if you are not ready to test.

The zones are set as a percentage of your 2k power, not as a fixed number of seconds, and the reason is the monitor's own physics: Concept2 states watts = 2.80 divided by pace cubed, with pace in seconds per metre. Power rises with the cube of speed. A percentage of watts therefore becomes a smaller percentage of split: row at 55-65% of your 2k watts and your split is 15-22% slower than 2k pace, which for a 1:45 rower is 16-23 seconds slower per 500m and for a 2:15 rower is 21-30 seconds. The "2k plus 20" rule of thumb fits one rower and misses the rest. The erg calculator converts split to watts and back; what a split is and how to hold one is covered in the erg splits guide.

Re-anchor after each 8-12 week block, or when a UT2 split that used to hold at 140 bpm sits at 130. The anchor moved.

The zone table: every band from your 2k

Take your 2k watts, multiply by the percentage, convert back to a split. Stroke rate is part of the prescription, heart rate and lactate are the ceiling to check against, and the last column is the share of weekly rowing time each band gets.

A 7:00 2k is a 1:45.0 split, 302 watts, so the table gives UT2 at 166-197 watts, which is 2:01-2:08 per 500m at 18-20 spm, with UT1 landing at 1:56-2:01, AT at 1:51-1:56, TR at 1:47-1:51 and AN at 1:42-1:47. An 8:00 2k (2:00.0, 203 watts) sets UT2 at 2:18-2:26, UT1 at 2:12-2:18, AT at 2:07-2:12, TR at 2:02-2:07 and AN at 1:56-2:02. If those UT2 numbers look slow, that is the point. Everyone's do.

The watt percentages are the convention most erg pace calculators run on, the UT2 and UT1 heart rates are British Rowing's, and the AT, TR and AN bands are the usual extension of the same model and drift a few points between tables, one more reason the split sets the session. The rate column runs a stroke wider at the top of UT2 and UT1 than British Rowing's published 18-19 and 20-22. That leaves room for individual variation.

Stroke rate is half the prescription

Two rowers can hold 2:05, one at 19 strokes a minute and one at 27, and they are doing different sessions. At 19 each stroke carries more force. At 27 the same watts come from tempo, the legs never load, and the session drifts toward UT1 physiology with a UT2 split on the screen. British Rowing writes the rate into every piece for that reason, and its published programme sets UT2 at 18-19 and UT1 at 20-22, with the harder pieces climbing from the mid-20s into the low 30s as the weeks progress, which is where threshold and race-pace work land.

• Cap UT2 at 20. If the split is only reachable at 22-24, the split is wrong for your fitness. Slow down. Hold the cap.
• Let rate climb with the zone. Each step up the table adds roughly 2-4 strokes per minute: threshold at 20 spm turns into a strength session, sprints at 24 are a drill.
• Watch for rate creep inside a piece. Finishing a 60-minute UT2 row at 22 when you started at 19 is the same fatigue signal as a rising heart rate, and the average rate on the summary screen hides it. The per-split rate shows it.

Technique is its own guide. Here the rate is a dial that keeps the zone honest.

Split sets the session, heart rate polices it

On the erg the power reading is exact and instant. Heart rate is neither. It takes a few minutes to catch up at the start of a piece, and over a long row it drifts upward at the same split as you heat up and lose fluid. Chase a heart rate number in the first ten minutes and you row UT2 too hard; hold a heart rate ceiling for 90 minutes and you finish at a recovery paddle. So the order is: set the split from the table, hold the rate cap, and treat heart rate as the alarm.

Three signals worth acting on:

• Heart rate above the band at the correct split, early. You are not recovered. Poor sleep, or a hard lift the day before, and a resting heart rate trend from your watch usually confirms it that morning. Drop the split 3-5 seconds and finish the session as recovery.
• Heart rate below the band at the correct split, week after week. Fitness moved. Re-test rather than freelance a faster UT2.
• Drift past the ceiling in the back half of a long UT2. Ease the split, keep the rate. That is the piece doing its job.

How much of the week belongs in each band

The share of time is where the science is loudest. Across sports, elite endurance athletes training 10-13 times a week converge on about 80% of sessions at low intensity, around 2 mmol/L, with about 20% built around hard intervals near 90% of VO2max. Rowers lean further. The junior world-class German rowers logged 95% of rowing time below 2 mmol/L, 2% between 2 and 4, and 3% above 4, and the share stayed near 95% through the whole season. A 2024 systematic review of 14 studies landed on 75-80% low intensity with 15-20% high as the mix that moved VO2max and work economy most.

Turn that into a recreational week:

• Four to five hours of rowing. Three to three and a half hours in UT2 across three rows of 45-70 minutes, one AT session of 3-4 x 8 minutes, one TR session of 5-6 x 3 minutes, and AN as a few 30-second bursts at the end of a UT2 row. UT1 is the last 10 minutes of one steady row. Not a session of its own.
• Two to three hours. Two UT2 rows and one hard session that alternates AT and TR week to week. Skip AN until the 2k is within 8 weeks.
• Six hours or more. Add UT2 before anything else. The hard sessions stay at two; the third hard day is what breaks people.

Count minutes, not sessions. A 60-minute UT2 row and a 20-minute threshold piece are one session each, and the week is 75% steady state by the clock. A week-by-week build to a 2k is a plan; this is the distribution the plan has to respect.

The classic error: every session in the middle

Here is the pattern. A rower with a 7:00 2k pulls 40 minutes at 1:57-2:00 at 24 spm, four days a week, heart rate 155-165 the whole way, 80-84% of max. Feels productive. The monitor shows a respectable split, the session leaves a pleasant tiredness, and the 2k has been 7:00 for a year.

That pace is UT1 drifting into AT: too hard to recover from and repeat four or five times a week, too easy to touch the VO2max ceiling. It is the erg version of what runners call the moderate-intensity rut. The experiments are unkind to it. Twelve sub-elite runners were split into two groups for five months: the group at 80% low, 12% moderate and 8% high improved a 10.4 km race by 157 seconds; the group at 67% low and 25% moderate improved by 121. Same high-intensity dose, more middle, less result. In a nine-week trial of 48 trained endurance athletes, the polarized group raised VO2peak 11.7% and time to exhaustion 17.4%, while the threshold-training group made no further gains on any performance variable.

Rowing has its own version of that data. Norwegian medal-winning rowers between the 1970s and the 1990s moved training below 2 mmol/L from 30 to 50 hours a month, cut race-pace and supramaximal work from 23 hours to about 7, and their VO2max rose 12% while 6-minute erg performance rose almost 10%. More hours, slower hours. Faster races.

How to tell you are in the middle:

• Your steady rows average more than 75% of 2k watts.
• Your hard days cannot hit TR splits past the second interval.
• Every session's average heart rate lands between 150 and 168, whatever the plan said.
• Rate on "easy" days sits at 22-26.

The fix costs nothing but ego. Slow UT2 down to the band, 5-8 seconds for most people, cap the rate at 20, and hold it for three weeks. The hard days get harder on their own once the easy days stop stealing from them.

How Movement Rebels fits

The zones only work if someone tracks the share of the week you spend in each and adjusts. With the Concept2 integration each erg session lands in the app with its split, stroke rate and duration, and the coach reads your training intensity distribution, the share of time by zone. It also reads the HRV and resting heart rate your Garmin or Apple Health syncs overnight, your morning check-in, and the lifts you log. So in a week where the UT2 rows crept up to UT1 power, resting heart rate is 6 bpm over baseline and Thursday was a heavy deadlift day, the Sunday plan turns Saturday's planned TR session into a capped UT2 row and moves the intervals to Tuesday. Write your 2k in Notes for your coach. The anchor is then in the brief it reads each week.

Set the bands once from an honest 2k. Then row 75% of your minutes slower than feels impressive.