Aerobic Versus Anaerobic Effort on the Erg — A Research-Grade Synthesis

Abstract

Aerobic and anaerobic effort are not the on/off switch the older textbooks describe. The peer-reviewed literature now treats them as overlapping contributors: aerobic ATP provision dominates from the first stroke, and the anaerobic systems add a smaller, intensifying share as pace and power rise ([3] Brooks 1986, Level 5; [4] Holloszy & Coyle 1984, Level 5; [5] Hargreaves & Spriet 2020, Level 5; [6] Baker, McCormick & Robergs 2010, Level 5). The phosphocreatine system supplies the first ~6–10 seconds, the glycolytic system dominates between 10 s and roughly 2 min, and the oxidative system contributes most of the ATP for pieces longer than ~2 min ([8] Hagerman 1984, Level 5; [9] Mahler et al. 1984, Level 5; [10] Steinacker 1993, Level 5). On the rowing ergometer, the aerobic share of energy provision shifts roughly from 50% at 500 m to 80% at 6 min, and 90% at 30 min ([8] Hagerman 1984, Level 5; [11] Volianitis, Yoshiga & Secher 2020, Level 5). The lactate shuttle operates from the first stroke: lactate is a fuel, not a waste product, and lactate threshold is a transition zone, not a single line ([3] Brooks 1986, Level 5; [12] Brooks 1986, Level 5; [13] Gladden 2004, Level 5; [14] Messonnier et al. 2013, Level 5; [7] Poole et al. 2021, Level 5). The peer-reviewed Borg RPE at the lactate threshold is about 11–13 in trained adults, and the talk test (last positive stage) tracks ventilatory threshold closely ([19] Scherr et al. 2013, Level 2b; [22] Reed & Pipe 2014, Level 5). The modern training consensus is that the polarised distribution — roughly 80% of session time below LT1, 20% above LT2 — is the empirically dominant distribution in elite rowers and elite endurance athletes ([25] Seiler & Kjerland 2006, Level 4; [28] Stöggl & Sperlich 2014, Level 5; [29] Ingham et al. 2008, Level 2b). The 2K is a synthesis test, and the peer-reviewed literature places it on the aerobic-anaerobic spectrum: power at VO2max, power at lactate threshold, and peak power together explain 98% of 2K speed variance in 41 elite rowers ([26] Ingham et al. 2002, Level 2b). The AI coach that reads the monitor alongside the rower's breathing, RPE, and talk-test response is reading energy-system demand correctly; the coach that asks the rower to "be in the aerobic zone" without naming the pace and duration that defines it is not.

What "aerobic" and "anaerobic" actually mean

The body produces ATP — the energy currency of muscle contraction — through three pathways. The phosphocreatine (PCr) system breaks down stored phosphocreatine to resynthesise ATP, releases no lactate, and reaches its peak rate within the first second of exercise. The glycolytic system breaks down muscle glycogen and blood glucose to pyruvate and lactate, and reaches its peak rate by 5–10 seconds. The oxidative system — the "aerobic" system — oxidises carbohydrate and fat in the mitochondria, and reaches its peak rate over 1–3 minutes of sustained exercise ([3] Brooks 1986, Level 5; [5] Hargreaves & Spriet 2020, Level 5; [6] Baker, McCormick & Robergs 2010, Level 5).

The older framing treated these as sequential systems — "PCr first, glycolysis next, oxidative last" — but the 2010 [6] Baker, McCormick & Robergs paper placed the field on the modern footing: all three systems contribute simultaneously from the first stroke. The proportion shifts with intensity and duration, but the systems are not stacked in time, only in peak power ([6] Baker, McCormick & Robergs 2010, Level 5; [7] Poole et al. 2021, Level 5). The 1984 [4] Holloszy & Coyle review anchored the mechanistic basis: the aerobic system is the only system that adapts to repeated training, and the increase in mitochondrial density and capillary supply is the long-term reason that endurance training improves performance ([4] Holloszy & Coyle 1984, Level 5). The 2020 [5] Hargreaves & Spriet review added the substrate side — carbohydrate oxidation rises sharply with intensity, fat oxidation peaks at moderate intensities and falls as intensity rises, and the crossover from fat to carbohydrate dominance is part of the aerobic-to-anaerobic transition ([5] Hargreaves & Spriet 2020, Level 5).

Energy systems are a continuum, not a switch

The dominant-energy-system framing is useful for intuition, but it is misleading if taken literally. The 2010 [6] Baker, McCormick & Robergs paper consolidated the modern position: the three energy systems contribute simultaneously, and the dominant system — the one supplying the largest fraction of ATP at a given moment — shifts as a continuous function of intensity and duration ([6] Baker, McCormick & Robergs 2010, Level 5). The 2021 [7] Poole, Rossiter, Brooks & Gladden review — 50+ years after Wasserman's original anaerobic-threshold paper — placed the field on the modern mechanistic footing: lactate is a fuel, not a waste product, and the transitions between energy-system dominance are gentle curves, not step changes ([7] Poole et al. 2021, Level 5; [15] Wasserman & McIlroy 1964, Level 5; [16] Beaver, Wasserman & Whipp 1986, Level 5; [3] Brooks 1986, Level 5).

The practical duration bands for energy-system dominance are approximately as follows, from the 1984 [8] Hagerman review and the 1984 [9] Mahler et al. companion paper: at 6 s, the PCr system supplies roughly 70–80% of ATP and oxidative supply is roughly 10–20%; at 60 s, the glycolytic system dominates at roughly 50–60% and oxidative supply is roughly 30–40%; at 2 min, glycolytic and oxidative contribute roughly equally; at 6 min, oxidative supply dominates at roughly 80%; at 60 min, oxidative supply is roughly 90–95% ([8] Hagerman 1984, Level 5; [9] Mahler et al. 1984, Level 5). The 1993 [10] Steinacker paper sharpened the rower-specific framing: elite rowers have 70–85% slow-twitch fibres and the aerobic-anaerobic threshold sits at 80–85% of maximal performance, so the dominance transition happens at a higher percentage of VO2max in rowers than in cross-country skiers or distance runners ([10] Steinacker 1993, Level 5). For a broader exploration of how whole-body musculature and endurance capacity develop on the ergometer, see our comprehensive synthesis on what indoor rowing trains.

The 2020 [11] Volianitis, Yoshiga & Secher review is the modern rower-physiology anchor: the cardiovascular and metabolic demands of rowing are unusual because the rowing stroke engages ~85% of muscle mass and produces very high cardiac outputs at lower VO2 than running, and the on-water stress on pulmonary diffusion, cerebral blood flow, and neuromuscular activation is higher than the ergometer profile ([11] Volianitis, Yoshiga & Secher 2020, Level 5). The honest read for the indoor rower: the rower should care less about which system is "on" and more about the proportion of contribution at the pace and duration of the session they are doing.

Aerobic vs anaerobic contribution across rowing distances

The 1984 [8] Hagerman review remains the canonical reference for rowing-specific energy contributions. The table below is a synthesis of the duration × energy-system breakdown Hagerman reports, cross-referenced with the 1984 [9] Mahler et al. companion paper and the 2020 [11] Volianitis, Yoshiga & Secher update:

| Piece | Duration | Aerobic share | Anaerobic share | Primary sensation | |---|---|---|---|---| | 100 m | ~15–20 s | ~20–25% | ~75–80% (PCr + glycolytic) | All-out, sprint depletion | | 500 m | ~1.5–2 min | ~50% | ~50% (glycolytic dominant) | Breathless, lactate-burning | | 2K | ~6–8 min | ~75–80% | ~20–25% | Hard but rhythmic | | 5K | ~18–22 min | ~85% | ~15% | Sustainable with focus | | 6K | ~22–24 min | ~85–90% | ~10–15% | Steady, lactate onset | | 30 min | 30 min | ~90% | ~10% | Pacing is everything | | 60 min | 60 min | ~95% | ~5% | Sustainable, fat oxidation |

The 1984 [8] Hagerman paper and the 1984 [9] Mahler et al. companion paper are the primary sources for these breakdowns; the 1993 [10] Steinacker paper provides the rower-specific muscle-fibre and threshold-position context; the 2020 [11] Volianitis, Yoshiga & Secher review is the modern restatement ([8] Hagerman 1984, Level 5; [9] Mahler et al. 1984, Level 5; [10] Steinacker 1993, Level 5; [11] Volianitis, Yoshiga & Secher 2020, Level 5). The 1984 [8] Hagerman paper is the single most important reference for any coach who wants to size a session by the energy-system share it is training.

The practical read is direct: a 30-minute steady piece is ~90% aerobic, so it trains the oxidative system. A 2K piece is ~75% aerobic, so it trains both the oxidative system and the glycolytic system. A 500 m sprint is ~50% aerobic, so it trains glycolysis and the oxidative system's ability to recover between intervals. The coach that knows these proportions can size weekly training to target each system in proportion.

The lactate shuttle: what lactate actually is

The 1986 [3] Brooks paper introduced the lactate shuttle: 75% of lactate produced during steady-rate exercise is removed by oxidation, and 20% is converted to glucose. The 1986 [12] Brooks Fed Proc paper formalised the same observation: lactate is produced under fully aerobic conditions, and the production-clearance balance is the central fact of lactate metabolism ([3] Brooks 1986, Level 5; [12] Brooks 1986, Level 5). The 2004 [13] Gladden review consolidated the modern view: lactate is a fuel shuttled between producer and consumer cells, and the body treats lactate as a circulating carbohydrate source, not a metabolic waste product ([13] Gladden 2004, Level 5).

The 2013 [14] Messonnier et al. paper quantified the kinetics: at the lactate threshold, lactate production equals lactate clearance, and the threshold is the work rate at which the production-clearance balance flips from net clearance to net accumulation ([14] Messonnier et al. 2013, Level 5). The 2021 [7] Poole et al. review — 50+ years after the original Wasserman paper — concluded that the original O2-limitation hypothesis is no longer tenable, and that lactate threshold is a transition zone, not a single line ([7] Poole et al. 2021, Level 5). The 1999 [18] Coyle paper placed the threshold in the endurance-performance framework: VO2max, lactate threshold, and economy together determine endurance performance, and the threshold is the single most trainable of the three ([18] Coyle 1999, Level 5; [27] Joyner & Coyle 2008, Level 5). For a deeper dive into the subjective and physiological markers of threshold work, read our dedicated article on lactate and the feeling of a hard sustainable pace.

The practical read is direct: lactate threshold is not a metabolic failure point. It is a transition zone where the body's clearance mechanisms begin to fall behind production, and the practical marker of that transition is the change in sensation — the shift from "hard sustainable" to "this is over within minutes." The lactate shuttle means that training at LT2 increases the body's clearance capacity, which is why the threshold itself is trainable ([18] Coyle 1999, Level 5; [4] Holloszy & Coyle 1984, Level 5; [29] Ingham et al. 2008, Level 2b).

The lactate threshold: what the rower can read

The peer-reviewed literature now treats lactate threshold as a transition zone, not a single number. The 1979 [17] Kindermann, Simon & Keul paper operationalised it as a work rate at which lactate first rises above resting values during a graded exercise test. The 1986 [16] Beaver, Wasserman & Whipp paper introduced the V-slope method, the gas-exchange implementation of the threshold concept. The 2021 [7] Poole et al. review — 50+ years after the original Wasserman paper — placed the field on the modern footing: the threshold is a transition zone, not a single line, and the original O2-limitation hypothesis is no longer tenable ([7] Poole et al. 2021, Level 5; [15] Wasserman & McIlroy 1964, Level 5; [17] Kindermann, Simon & Keul 1979, Level 5; [16] Beaver, Wasserman & Whipp 1986, Level 5).

The 2013 [19] Scherr et al. paper is the most direct anchor for what the rower can read: in 2,560 men and women, Borg RPE correlated with blood lactate at r = 0.83 and with HR at r = 0.74. RPE at the lactate threshold was about 10.8; RPE at IAT was about 13.6; RPE at the fixed 4 mmol/L threshold was about 14.1 ([19] Scherr et al. 2013, Level 2b). The 2014 [22] Reed & Pipe review established that above VT/LT, comfortable speech is not likely possible ("negative" stage); below it, the "equivocal/last positive" stage is possible. The talk test is the field-deployable cue for the LT2 boundary ([22] Reed & Pipe 2014, Level 5).

The 2001 [20] Tanaka, Monahan & Seals paper anchored the HR anchor: the 208 − 0.7×age formula. The 2001 [21] Coyle & González-Alonso paper added the drift caveat: HR drifts 10–30 bpm over a steady piece, so HR alone is a noisy cue — the rower should track split-time and pace alongside it ([20] Tanaka, Monahan & Seals 2001, Level 5; [21] Coyle & González-Alonso 2001, Level 5). To see how to interpret heart rate variability and drift alongside monitor feedback without treating HR zones as absolute limits, review our heart rate zones guide. The honest read for the indoor rower: the hard sustainable pace is roughly 12–13 on Borg CR-10 — "somewhat hard" to "hard" — and you can say a few words but cannot hold a conversation. Below it, conversation is comfortable. Above it, speech becomes impossible and the effort is fundamentally time-limited.

Reading your monitor: pace, HR, RPE, and the talk test

The peer-reviewed literature converges on four field-deployable cues for energy-system demand: pace, HR, RPE, and the talk test. Each has strengths and limitations.

Pace is the most directly controllable variable. The 1984 [8] Hagerman review provides the duration × energy-system contribution table, and the 1984 [9] Mahler et al. companion paper provides the duration × pace reference. The 2020 [11] Volianitis, Yoshiga & Secher review is the modern rower-physiology anchor. The practical translation: a rower at 2K pace is at ~75% aerobic; a rower at 30-minute pace is at ~90% aerobic ([8] Hagerman 1984, Level 5; [9] Mahler et al. 1984, Level 5; [11] Volianitis, Yoshiga & Secher 2020, Level 5). The 2002 [26] Ingham et al. paper sharpened the 2K reading: power at VO2max, VO2 at LT, power at 4 mmol/L lactate, and peak power together explained 98% of 2K speed variance in 41 elite rowers ([26] Ingham et al. 2002, Level 2b).

HR is a useful but noisy cue. The 2001 [20] Tanaka, Monahan & Seals paper anchored the 208 − 0.7×age formula. The 2001 [21] Coyle & González-Alonso paper added the drift caveat: HR drifts 10–30 bpm over a steady piece, especially in heat, so HR alone is not a reliable intensity marker across a long session ([20] Tanaka, Monahan & Seals 2001, Level 5; [21] Coyle & González-Alonso 2001, Level 5). The 2001 [21] Coyle paper is the methodological anchor for pairing HR with pace and RPE rather than relying on it alone.

RPE is a robust cue when the rower is experienced. The 2013 [19] Scherr et al. paper established RPE at LT ~10.8 in trained adults. The 2023 [31] Gaskill, Skinner & Quindry paper confirmed it in a larger and more varied sample: in 863 adults, mean RPE at the ventilatory threshold was 12.5 ± 0.93 ([31] Gaskill, Skinner & Quindry 2023, Level 2b). The honest read: a hard sustainable pace is roughly 12–13 on Borg CR-10, and the standard deviation is wide enough that a single RPE read is not a calibration of physiology ([19] Scherr et al. 2013, Level 2b; [31] Gaskill, Skinner & Quindry 2023, Level 2b).

The talk test is the most practical field cue. The 2014 [22] Reed & Pipe review established that above VT/LT, comfortable speech is not likely possible; below it, the "equivocal/last positive" stage is possible. The 2023 [32] Kwon, Kang & Chang paper validated the talk test in 17 healthy adults on a treadmill: three stages showed significant linear correlations with HR, VO2, RER, ventilation, tidal volume, and respiratory rate. The practical translation: long sentences are below LT1, short sentences are around LT1, and broken words are at or above LT2 ([22] Reed & Pipe 2014, Level 5; [32] Kwon, Kang & Chang 2023, Level 2b).

The honest read for the indoor rower: pace, HR, RPE, and the talk test are four orthogonal cues, and the coach that reads all four together — not any one alone — is reading energy-system demand correctly.

Practical session templates by energy-system target

The 2006 [25] Seiler & Kjerland review established the modern training-distribution framework: elite endurance athletes train ~75% below VT1, 7–8% between VT1 and VT2, and 17–22% above VT2. The 2014 [28] Stöggl & Sperlich paper — Frontiers randomised study — showed that polarised distribution outperforms threshold, high-intensity, and high-volume training on key endurance variables. The 2008 [29] Ingham et al. paper provided the experimental anchor: in 18 trained rowers, the LOW group (polarised distribution) gained 23.5 ± 12.2 W at LT vs 5.1 ± 5.0 W in the MIX group over 12 weeks ([25] Seiler & Kjerland 2006, Level 4; [28] Stöggl & Sperlich 2014, Level 5; [29] Ingham et al. 2008, Level 2b). For an in-depth comparison of intensity distributions, see our review of polarized vs pyramidal endurance training.

The practical templates below target each energy-system band with a rower-appropriate session. The rate bands are the 2020 [11] Volianitis reference and the Concept2 stroke-rate bands the Concept2 stroke-rate guide documents ([23] World Rowing, Level 5; [24] Concept2 — Stroke rate, Level 5).

Template 1 — Pure aerobic (steady state, 60–90 min). Pace: 30–40 sec/500 m slower than 2K pace. Rate: 18–20 spm. Sensation: easy conversation, RPE 9–11. Energy-system target: 95%+ aerobic. Frequency: 2–3× per week. Anchor: the 1984 [8] Hagerman review and the 2006 [25] Seiler paper.

Template 2 — Threshold (4 × 8 min at LT2, 2 min rest). Pace: 2K pace + 4–6 sec/500 m. Rate: 22–24 spm. Sensation: short sentences only, RPE 13–14. Energy-system target: 85% aerobic, 15% glycolytic. Frequency: 1× per week. Anchor: the 2013 [19] Scherr et al. RPE-LT paper and the 2014 [22] Reed & Pipe talk-test review.

Template 3 — VO2max (5 × 3 min at 2K pace, 3 min rest). Pace: 2K pace. Rate: 26–28 spm. Sensation: broken words, RPE 15–17. Energy-system target: 75% aerobic, 25% glycolytic. Frequency: 1× per week. Anchor: the 2002 [26] Ingham et al. 2K-determinant paper and the 1984 [8] Hagerman review.

Template 4 — Glycolytic (8 × 500 m at 2K + 10–12 sec, 2 min rest). Pace: 500 m PR pace + 10–12 sec/500 m. Rate: 28–32 spm. Sensation: lactate-burning, RPE 17–19. Energy-system target: 50% aerobic, 50% glycolytic. Frequency: 1× per week. Anchor: the 1984 [8] Hagerman review and the 1993 [10] Steinacker paper.

Template 5 — PCr / neuromuscular (6 × 30 s sprint, 4 min rest). Pace: all-out. Rate: 36–44 spm. Sensation: maximal, RPE 20. Energy-system target: 70–80% PCr. Frequency: 1× per week. Anchor: the 2010 [6] Baker, McCormick & Robergs paper and the 1984 [8] Hagerman review.

The five-template scheme is an application of the polarised-distribution principle to the indoor ergometer. The 2006 [25] Seiler paper is the empirical anchor; the 2014 [28] Stöggl & Sperlich paper is the modern experimental anchor; the 1984 [8] Hagerman review is the duration × energy-system reference for the rate bands and pace bands. The 2K, 5K, and 30-minute test distances are the standard federation-recognised indoor-rowing test distances, and the [30] British Rowing Go Row Indoor tests document is the practical reference for coach-supervised testing ([30] British Rowing, Level 5). For benchmark pacing guidelines on longer aerobic trials, see our analysis in the 5K erg test pacing guide.

The 2K as a synthesis test

The 2K is the canonical indoor-rowing race distance, and the peer-reviewed literature places it on the aerobic-anaerobic spectrum. The 2002 [26] Ingham et al. paper is the most direct anchor: in 41 elite rowers, a regression model with power at VO2max, VO2 at lactate threshold, power at 4 mmol/L lactate, and peak power explained 98% of 2K speed variance ([26] Ingham et al. 2002, Level 2b). The 1999 [18] Coyle paper provided the synthetic framework: VO2max, lactate threshold, and economy together determine endurance performance, and the 2K is the test that sits on all three ([18] Coyle 1999, Level 5; [27] Joyner & Coyle 2008, Level 5). For an in-depth breakdown of how pacing strategy and physiological components dictate performance, see what a 2K result actually tells you as well as understanding VO2max on a rowing machine.

The 1984 [8] Hagerman review anchored the 2K as a synthesis of aerobic and anaerobic energy systems; the 2020 [11] Volianitis, Yoshiga & Secher review is the modern restatement. The 2008 [29] Ingham et al. paper is the experimental anchor: low-intensity rowing volume is the dominant driver of adaptation, and the polarised distribution is the empirically dominant shape in elite rowers ([8] Hagerman 1984, Level 5; [11] Volianitis, Yoshiga & Secher 2020, Level 5; [29] Ingham et al. 2008, Level 2b).

The 2002 [26] Ingham et al. paper is the methodological anchor for the 2K as a synthesis test: a 2K is roughly 75% aerobic and 25% glycolytic at the elite level, and the rower's lactate threshold is one of the strongest single predictors of 2K performance. The honest read for the indoor rower: the 2K is a synthesis test, and the rower who trains both the aerobic and glycolytic systems sees a real but bounded improvement in 2K performance.

Limitations and open questions

The rowing-specific energy-system contribution literature is small. Most of the foundational papers are in cycling, running, or general exercise physiology, with rowing-specific work concentrated on the 1984 [8] Hagerman review (a synthesis of the prior literature) and the 2020 [11] Volianitis, Yoshiga & Secher review. The 1984 [8] Hagerman review is the most direct anchor for indoor-rowing energy-system contributions, and the 1984 [9] Mahler et al. companion paper is the most direct anchor for rower-specific duration × energy-system breakdown. The 1993 [10] Steinacker paper is the muscle-fibre anchor. The reader should weight the rowing-specific evidence more heavily than the cross-sport evidence when the two diverge. For a broader survey of the rowing physiology literature, the [1] PubMed rowing-research index and the [2] European College of Sport Science position stand are the natural starting points.

The fixed 4 mmol/L threshold is not the gold standard. The 1979 [17] Kindermann, Simon & Keul paper established the 4 mmol/L threshold as an operational choice, and the 2021 [7] Poole et al. review catalogued the field's convergence on the threshold-as-transition-zone framing. The reader who treats the AT on a training plan as the same as the lab-measured lactate threshold is over-fitting the model.

The RPE and talk-test anchors are robust but bounded. The 2013 [19] Scherr et al. paper established that RPE at LT is about 10.8 in trained adults, but the standard deviation is wide ([19] Scherr et al. 2013, Level 2b). The talk test is a useful practical tool, but it is one of several — the coach that anchors the rower's reference pace on a single talk-test read is over-fitting.

The indoor ergometer profile is not the on-water profile. The 2020 [11] Volianitis, Yoshiga & Secher review noted that the on-water 2K profile is more front-loaded than the ergometer profile, and the on-water stress on pulmonary diffusion, cerebral blood flow, and neuromuscular activation is higher than the ergometer profile ([11] Volianitis, Yoshiga & Secher 2020, Level 5). The reader who rows both should treat the ergometer and on-water energy-system demands as distinct.

The energy-system contributions are bounded to the lab setting. The 1984 [8] Hagerman review is a synthesis of laboratory measurements, and the 1984 [9] Mahler et al. companion paper is the same. The peer-reviewed literature on indoor-rowing energy-system contributions is concentrated on the 1984 [8] Hagerman review and the 2020 [11] Volianitis, Yoshiga & Secher update. The reader should treat the contribution percentages as order-of-magnitude estimates, not as precise fractions.

What to do with this article

Read the principle: aerobic and anaerobic effort are not an on/off switch. The peer-reviewed literature treats them as overlapping contributors, and the proportion of contribution shifts with intensity and duration. Read the evidence: the 1984 [8] Hagerman review (Level 5) is the canonical aerobic-vs-anaerobic contribution table for indoor rowing; the 1986 [3] Brooks paper (Level 5) and the 2021 [7] Poole et al. review (Level 5) anchor the "lactate is a fuel, not a waste product" framing; the 2013 [19] Scherr et al. paper (Level 2b) and the 2014 [22] Reed & Pipe review (Level 5) anchor the RPE and talk-test cues; the 2006 [25] Seiler & Kjerland paper (Level 4) and the 2014 [28] Stöggl & Sperlich paper (Level 5) anchor the polarised-distribution claim. Read the practical read: the rower should care less about which system is "on" and more about the proportion of contribution at the pace and duration of the session they are doing; a 30-minute steady piece is ~90% aerobic, a 2K is ~75% aerobic, and a 500 m sprint is ~50% aerobic; the talk test is the most practical field cue, and the AI coach that reads the monitor alongside the rower's breathing, RPE, and talk-test response is reading energy-system demand correctly.

When you want to anchor a session by energy-system target, the practical recipe is: pick the template (1–5) that targets the share you want to train; set the pace to the duration × energy-system table the 1984 [8] Hagerman review reports; set the rate to the rate-by-duration bands the 2020 [11] Volianitis review and the Concept2 stroke-rate guide document; check the rower's RPE against the 2013 [19] Scherr et al. paper's RPE-LT anchors; verify with the talk test; and treat the energy-system proportions as order-of-magnitude estimates, not as precise fractions. The AI coach that reads the monitor alongside the rower's breathing, RPE, and talk-test response is reading energy-system demand correctly; the coach that asks the rower to "be in the aerobic zone" without naming the pace and duration that defines it is not.