SYNTH-40 · Guide
Prescribing and reading a session without a power meter
The instruments that survive, and the ones that quietly stop working
The decision this framework makes
How to write a session, and how to judge the session that came back, when the only inputs are perceived effort, heart rate, pace, time and terrain.
Key Findings — what still works without a meter
Perceived effort is an instrument, not a vibe. Foster's session-RPE has a protocol — about 30 min after the session, rate the whole effort on the Borg CR-10 scale; multiply by duration in minutes for a load in arbitrary units — and Foster 2001's abstract reports a "highly consistent" relationship between the session-RPE score and an HR-based objective method across steady-state cycling, interval cycling and basketball (REF-500; the abstract gives no correlation coefficients — the r 0.75-0.90 range and lactate / %VO2max criteria once quoted for sRPE are in no abstract and have been deleted from that composite entry).
Subjective measures track the training response more sensitively than most objective ones (REF-368). Inference from that: losing the power meter loses precision, not the signal (the review compared self-report with physiological markers, not with power).
The signal behind the talk test survives fatigue better than power does (the talk test itself was not tested). In 14 endurance-trained cyclists and triathletes, ventilation at the first ventilatory threshold was unchanged after two hours of moderate cycling (72 ± 12 vs 69 ± 13 L/min, P = 0.075; within-subject CV 5.4%) while power at that boundary fell ~10% (REF-180). *Inference from that:* full sentences means the moderate domain; laboured speech means the boundary has been crossed — and that stays true late in a long ride, when a fixed wattage no longer describes the same domain.The paper measured ventilation, not speech, and two hours, not five; the talk test as a proxy for ventilation is the base's own practice.Breathing rate itself tracks effort: in 9 well-trained male cyclists riding self-paced 10-, 20- and 30-min time trials, respiratory frequency, not heart rate, minute ventilation or VO2, followed RPE with the same time course in every trial (REF-1083, B, crossover); a Perspective from the same group argues that breathing rate is a strong marker of physical effort and follows workload changes in intervals quickly (REF-1084, C+, opinion).Neither tested speech, so reading effort from breathing in the field remains the base's own practice.
A threshold heart rate taken from the athlete's own hard effort is a usable anchor; a percentage of an age-estimated maximum is not. Age formulas carry RMSE 9.1-10.5 bpm on the individual, and 9 of 13 formula-mode combinations differed significantly from the measured value in 5069 endurance athletes (abstract count; 5311 in the Results, corrected 2026-10-12) (REF-3494, and SYNTH-38 for what to do about it).
Perceived effort can move on its own. After 90 min of a demanding cognitive task, 16 subjects cycling at 80% peak power lasted 640 ± 316 s against 754 ± 339 s in the control condition (about 15% shorter) and rated effort significantly higher, with cardiorespiratory and muscle-energetic responses largely unaffected (REF-370, randomised crossover) — so effort-based prescription needs the athlete's context, not just their rating.
Triangulating talk test with heart rate is the base's own practice, not a documented Norwegian method — the REF-302 entry (12 coaches of world-class athletes) describes session models (voluminous, controlled intervals; far more moderate than high-intensity sessions) and carries nothing about lactate-free monitoring.
1. Set the anchor once
Threshold heart rate from a 20-30 min maximal steady effort, averaging the last 20 minutes (SYNTH-38). A convention, not a finding — say so.
For runners, a threshold PACE from the same effort on flat terrain, and keep it as a pace, not a heart rate, whenever the route allows a steady effort (a convention, like the heart-rate anchor).
If the athlete will not test, anchor on effort alone. That is a worse anchor, not an unusable one.
2. Write the session in the language the athlete can execute
| Session type | How to prescribe it without a meter (practice, not evidence — conventions assembled from the cited principles) |
|---|---|
| Easy / recovery | Talk test — full sentences throughout. Cap by time, not distance. Heart rate as a ceiling, never as a target |
| Long aerobic | Talk test at the top end of conversational; a heart-rate ceiling for the first hour only (house convention — no entry sets one hour), then expect drift, most of all in the heat, and let the ceiling go (REF-3496: +11% over minutes 15-45 at 35 °C vs +2% at 22 °C) |
| Threshold / sustained | Threshold heart rate or threshold pace, with RPE 7-8 on CR-10 as the cross-check; reps of 8-20 min so heart rate has time to arrive |
| VO2max intervals | Effort and repeatability, NOT heart rate. Prescribe "the hardest pace all reps can be completed at" and judge by whether the last rep matched the first (SYNTH-33) |
| Short / neuromuscular | Effort and duration only. Heart rate is meaningless here — the rep ends before the response arrives |
| Hills, in place of intervals | Gradient and time substitute for a power target well; the same hill at the same effort is a repeatable test |
3. Read the completed session
Ask for one sRPE about 30 minutes afterwards, on the same scale every time (REF-500). That single number, tracked against the athlete's own history, is the backbone of load monitoring without a meter.
Judge quality by repeatability, not by an average. Did the last interval match the first? Did the pace hold to the end of the long run? That question needs no power meter and answers more than a zone distribution would.
Read heart rate as a comparison against the athlete's own similar sessions in similar conditions — never against a table, and never as a percentage of a formula (REF-3494).
Expect drift, and know it is mostly weather. A hot session's heart rate is not comparable to a cool one's (REF-3496).
Progress by symptoms and by whether the last session was completed (base practice), not by a fixed weekly percentage — the systematic review behind the "10% rule" found "very limited evidence" that a sudden change in training load is associated with injury, and no difference in injury between 10% and 24% weekly increases (REF-565); what the cohort data in recreational runners do show is that a 20-60% jump in weekly distance costs injuries in the next three weeks (REF-623; both sources are running studies — for cycling this is a transfer).
Practical Application
Write the session in effort, time and terrain, and give the heart-rate or pace number as a cross-check rather than as the target. An athlete who cannot execute the prescription has not been given one.
Use the talk test as the primary marker of the moderate-domain boundary (easy and long aerobic work), including hour five of a long ride — the base's own practice, reasoned from the ventilation result below. Ventilation at VT1 is the one boundary marker in this base shown to hold after two hours of cycling, while power at the same boundary falls ~10% (REF-180); its extension to hour five is inference.
Collect one session RPE about half an hour after every session on a fixed 0-10 scale (REF-500) — that is the load record, and it is a validated one.
Judge intervals by whether the reps held together, not by time-in-zone. The fraction of VO2max sustained is what predicted adaptation in 22 well-trained cyclists, and %HRmax related to fewer outcomes and repeated worse (REF-041, SYNTH-16); judging by whether the reps held together is the base's own practice (SYNTH-33), not a finding of that study.
Never make a plan conditional on buying equipment. State honestly what a meter would add — a stable anchor and a per-interval target — and then give the athlete a complete plan that does not need one.
Say when the answer got softer. Fewer instruments means wider error bars, and the athlete should hear that from you rather than discover it.
What NOT to do
Do not translate a watt-based plan into heart-rate zones built on an age formula and present it as equivalent (REF-3494).
Do not prescribe short intervals by heart rate — the response arrives after the rep is over.
Do not chase a specific TSS or time-in-zone target with an athlete who has neither instrument to hit it with.
Do not quote critical power, W′ or FTP percentages to an athlete who cannot measure any of them.
Limitations
The session-prescription table in section 2 is practice, not evidence. The rep lengths, the RPE 7-8 band and the hill substitution are conventions assembled from the cited principles; no trial in this base compares effort-prescribed against power-prescribed training head to head.
The talk-test evidence is narrow — REF-180 is a 14-person cycling study of ventilation at the moderate-heavy boundary after 2 h; it did not test speech, threshold or above, or five-hour rides, and it is not a substitute for a measured boundary.
The field threshold protocol in section 1 has no validation study in this base (SYNTH-38).
Nothing here addresses swimming, where the equivalent anchor is a timed field test rather than effort, and this base's coverage of that is thin.
Strength training is out of scope; its own RPE conventions differ and live in the strength sections.
This card cannot restore precision. It describes how to train well with wider error bars, not how to match what a meter provides.
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B+ and 2026-10-01 from B (the instruments are B-level, the anchor and the prescription table are practice): the only A-level entry it cites is the systematic review REF-368; REF-370 and REF-3494 are B+, REF-180 is B and REF-500 is C+; the prescription conventions are labelled as conventions
Content correction 2026-09-27
"REF-302: Norwegian practice without lactate is talk test plus heart rate" -> not in REF-302's corrected entry (session models only); relabelled as the base's own practice, cross-reference dropped.
"REF-180: talk test survives five hours" -> the study is ventilation at VT1 after 2 h in 14 cyclists (72 vs 69 L/min, P = 0.075; power −10%); the talk test as a speech proxy and the five-hour extension are labelled inference.
"REF-370: RPE +0.5-1.0 points, TTE −12%, HR/lactate/VO2 unchanged" -> abstract: 640 vs 754 s (≈15%), RPE significantly higher, physiology "largely unaffected".
"REF-500: r 0.75-0.90 against TRIMP, lactate, %VO2max" -> Foster 2001's abstract gives a "highly consistent" HR-based relationship and no r-values; the range flagged as untraced composite.
"REF-129" -> duplicate entry; replaced with REF-044 (corrected, B, n=10 habitually active).
REF-3496 window and population stated; level parenthetical corrected (REF-3494 B+, REF-370 crossover n=16, REF-500 composite).
Sync after the full-base pass: REF-180 was regraded B+ -> B (uncontrolled pre/post, n=14); Level-line parenthetical updated. REF-565 wording aligned to its conclusion ("very limited evidence" that a sudden load change is associated with injury).
Level B+ -> B: REF-500, REF-370 and REF-3494 were cited as A-level primaries; they are C+/B+.
REF-370 limitation note: the entry has since been corrected (B+, 640 vs 754 s); the "still reads level A / quotes 12%" remark is out of date.
Resync 2026-09-28: "the r 0.75-0.90 range and the lactate / %VO2max criteria quoted in that composite entry REF-500" -> the corrected REF-500 has deleted them (Foster 2001's abstract gives no coefficients); restated as no longer in the entry. Level parenthetical "the consensus REF-368" -> REF-368 is a systematic review of 56 studies, not a consensus.
Verification 2026-10-01: 29 ref-bearing sentences/cells read against REF-500, REF-368, REF-180, REF-3494, REF-370, REF-3496, REF-3495, REF-302, REF-044, REF-120, REF-565, REF-623, REF-041 and the pointed lines of SYNTH-38/33/16; 22 OK.Every quoted number matches its entry (REF-180 72 ± 12 vs 69 ± 13 L/min, P=0.075, CV 5.4%, power ~−10%, n=14; REF-3494 RMSE 9.1-10.5, 9 of 13, n=5069; REF-370 640 vs 754 s, n=16; REF-3496 +11% vs +2%, 10 men; REF-041 n=22; REF-565 10% vs 24%; REF-623 20-60%, three weeks). No NUMBER or WRONG finding; the Level-line grades are all correct.
Verification 2026-10-01: rows counted = 4 anchor bullets (section 1) + 6 table rows (section 2) + 5 reading bullets (section 3). The prescription itself is practice and the card admits it in Limitations; the label is missing in the cells/lead, which is where the athlete-facing text is taken from.
Verification 2026-10-01: the weakest point is the talk test. The base holds one uncontrolled n=14 study of ventilation at VT1 after 2 h; speech was not measured. The body labels this as inference, but the lead, the Key-Findings heading and the first Practical bullet state it as fact and extend it to 'everything below threshold'.
Verification 2026-10-01: 'first hour' for dropping the heart-rate ceiling appears twice with REF-3496; neither drift entry contains that number.
Verification 2026-10-01: no contradiction found with SYNTH-38 (20-30 min effort, last 20 min, labelled convention in both) or SYNTH-39.
Revision 2026-10-04: Key Findings, talk-test bullet — added that breathing rate tracked RPE better than HR, VE or VO2 in 9 trained cyclists over 10-30 min self-paced TTs (REF-1083, Nicolò 2016, B) and the same group's Perspective (REF-1084, 2017, C+); speech not tested, so the talk test stays labelled practice; cross-reference added. No rule, default or level changed.