# Master citation list

The single source of truth for every quantitative claim in this skill. Each entry: full citation,
PMID/DOI, and a **confidence flag** from verification against PubMed / DOI resolvers.

**Confidence key:**
- ✅ **Confirmed** — PMID and/or DOI verified; title, authors, journal internally consistent.
- ⚠️ **Confirmed metadata, claim = commonly-cited/approximate** — the paper exists as cited, but the
  exact number attributed to it is widely-repeated rather than verified word-for-word in the source.
- ❌ **Not found** — could not be confirmed; **do not cite as fact.**

Verified as of 2026-07-20.

---

## Durability / fatigue resistance

**✅ Muriel et al. 2022** — fatigued-state power differentiates riders; fresh power does not.
Muriel X, Mateo-March M, Valenzuela PL, Zabala M, Lucia A, Pallarés JG, Barranco-Gil D. *Durability
and repeatability of professional cyclists during a Grand Tour.* Eur J Sport Sci. 2022;22(12):
1797–1804. **PMID 34586952 · DOI 10.1080/17461391.2021.1987528.**

**✅ Spragg, Leo & Swart 2023 (training characteristics)** — durability tracks accumulated
volume/load; fatigued profile varies more than fresh across a season. *This is the primary "load
dependency" cite.* Spragg J, Leo P, Swart J. *The relationship between training characteristics and
durability in professional cyclists across a competitive season.* Eur J Sport Sci. 2023;23(4):
489–498. **PMID 35239466 · DOI 10.1080/17461391.2022.2049886.**
> The crisp "reduced load maintains fresh power; sustained load maintains durability" phrasing is
> Spragg's applied *interpretation* of this data — attribute as commentary, not a quoted result.

**✅ Spragg, Leo & Swart 2023 (physiological characteristics)** — physiological correlates of
durability (higher VO2max, gross efficiency, fat oxidation). Spragg J, Leo P, Swart J. *The
Relationship between Physiological Characteristics and Durability in Male Professional Cyclists.*
Med Sci Sports Exerc. 2023;55(1):133–140. **PMID 35977108 · DOI 10.1249/MSS.0000000000003024.**

**✅ Maunder et al. 2021** — canonical definition of durability as a distinct profiling quality.
Maunder E, Seiler S, Mildenhall MJ, Kilding AE, Plews DJ. *The Importance of 'Durability' in the
Physiological Profiling of Endurance Athletes.* Sports Med. 2021;51(8):1619–1628.
**PMID 33886100 · DOI 10.1007/s40279-021-01459-0.**

---

## MTB / XCO demands

**✅ Hays et al. 2018** — XCO demand profile (~25% time above MAP; hard start); HR/power/VO2
dissociation (VO2 high on descents, %VO2max uncorrelated with %HRmax/%MAP). Hays A, Devys S, Bertin
D, Marquet LA, Brisswalter J. *Understanding the Physiological Requirements of the Mountain Bike
Cross-Country Olympic Race Format.* Front Physiol. 2018;9:1062.
**PMID 30158873 · DOI 10.3389/fphys.2018.01062.**

**✅ Prinz et al. 2021** — corroborating hard-number demand data (~30% top zone; 334 efforts ~4.3 s
at ~135% MAP). Prinz B, et al. *(power-profile / demands of XCO)* Int J Sports Physiol Perform. 2021.
**PMID 33848975 · DOI 10.1123/ijspp.2020-0758.**

**✅ Protzen et al. 2026** — systematic review: contemporary XCO shifted toward greater anaerobic
contribution while maintaining high aerobic demand; ~¼ race time above MAP. Protzen G, Inoue A,
Buzzachera CF, Doma K, Devantier-Thomas B, Herrero-Molleda A, García-López J, Boullosa D. *The
Physiology of Contemporary Olympic Cross-Country Mountain Biking: A Systematic Review.* Sports Med
Open. 2026;12:16. **PMID 41739301 · DOI 10.1186/s40798-026-00976-4.**

**✅ Impellizzeri et al. 2005** — aerobic predictors of XCO (mass-normalized threshold power/VO2).
*Frame r ≈ 0.6–0.9 as "across studies"; the elite-cohort raw VO2max did not separate riders.*
Impellizzeri FM, Marcora SM, Rampinini E, Mognoni P, Sassi A. *Correlations between physiological
variables and performance in high level cross country off road cyclists.* Br J Sports Med.
2005;39(10):747–751. **PMID 16183772 · DOI 10.1136/bjsm.2004.017236.**

**✅ Inoue et al. 2012** — anaerobic power predicts XCO race time (r = −0.79, p = 0.006). Inoue A,
Sá Filho AS, Mello FCM, Santos TM. *Relationship between anaerobic cycling tests and mountain bike
cross-country performance.* J Strength Cond Res. 2012;26(6):1589–1593.
**PMID 21912290 · DOI 10.1519/JSC.0b013e318234eb89.**

**✅ Sánchez-Jiménez et al. 2025** — fatigue-decline magnitudes: Top-10 ~6–10% vs lower ~15–20%.
Sánchez-Jiménez L, Javaloyes A, Peña-González I, Moya-Ramón M, Mateo-March M. *Record Power Profile
in Elite Olympic Cross-Country Mountain Bike Cyclists: Normative Values and Fatigue Effects.* Scand
J Med Sci Sports. 2025;35(11):e70170. **PMID 41285697 · DOI 10.1111/sms.70170.**

**✅ Novak et al. 2018** — marathon (4-h) MTB predictors differ from lap XCO. Novak AR, Bennett KJM,
Fransen J, Dascombe BJ. *Predictors of performance in a 4-h mountain-bike race.* J Sports Sci.
2018;36(4):462–468. **PMID 28406361 · DOI 10.1080/02640414.2017.1313999.**

---

## Strength training (incl. masters)

**✅ Llanos-Lagos et al. 2026 (epub 2025)** — meta-analysis, 17 studies / 262 cyclists: heavy
strength improves efficiency, anaerobic power, TT performance; **no VO2max effect**. Llanos-Lagos C,
Ramírez-Campillo R, Sáez de Villarreal E. *Heavy strength training effects on physiological
determinants of endurance cyclist performance: a systematic review with meta-analysis.* Eur J Appl
Physiol. 2026;126(1):193–222. **PMID 40632222 · DOI 10.1007/s00421-025-05883-2.** *(Certainty of
evidence noted as low by the authors.)*

**✅ Cadore et al. 2013 (epub 2012)** — strength-first sequencing yields greater strength gains in
the elderly (~35% vs ~22%). Cadore EL, Izquierdo M, Pinto SS, et al. *Neuromuscular adaptations to
concurrent training in the elderly: effects of intrasession exercise sequence.* Age (Dordr).
2013;35(3):891–903. **PMID 22453934 · DOI 10.1007/s11357-012-9405-y.** *(This is the "Cadore 2012"
sequencing cite.)*

**✅ Cadore & Izquierdo 2013** — interference manageable/muted in older adults except at high
volume/frequency. Cadore EL, Izquierdo M. *How to simultaneously optimize muscle strength, power,
functional capacity, and cardiovascular gains in the elderly: an update.* Age (Dordr).
2013;35(6):2329–2344. **PMID 23288690 · DOI 10.1007/s11357-012-9503-x.**

**⚠️ English & Paddon-Jones 2010** — commonly cited origin of "~8% muscle loss/decade after 40."
*Exact figure not verified in abstract; treat as commonly-cited/approximate.* English KL, Paddon-
Jones D. *Protecting muscle mass and function in older adults during bed rest.* Curr Opin Clin Nutr
Metab Care. 2010;13(1):34–39. **PMID 19898232 · DOI 10.1097/MCO.0b013e328333aa66.**

**✅ Volpi, Nazemi & Fujita 2004** — sarcopenia mechanisms; resistance/aerobic training as
countermeasure (fiber-type-fastest specifics not verbatim-confirmed). Volpi E, Nazemi R, Fujita S.
*Muscle tissue changes with aging.* Curr Opin Clin Nutr Metab Care. 2004;7(4):405–410.
**PMID 15192443 · DOI 10.1097/01.mco.0000134362.76653.b2.**

**✅ Cruz-Jentoft et al. 2019 (EWGSOP2)** — consensus: sarcopenia centers on muscle strength;
resistance training recommended. *Strongest confirmed cite for "loaded resistance is the primary
countermeasure."* Cruz-Jentoft AJ, et al. *Sarcopenia: revised European consensus on definition and
diagnosis.* Age Ageing. 2019;48(1):16–31. **PMID 30312372 · DOI 10.1093/ageing/afy169.**

---

## VO2max intervals

**✅ Yang, Wang & Guan 2025** — network meta-analysis, 51 studies / 1,261 athletes: inverted-U
dose-response; optimum ~140 s work, work:rest ~0.85. *Weighted toward running-based HIIT.* Yang Q,
Wang J, Guan D. *Comparison of different interval training methods on athletes' oxygen uptake: a
systematic review with pairwise and network meta-analysis.* BMC Sports Sci Med Rehabil.
2025;17(1):156. **PMID 40605061 · DOI 10.1186/s13102-025-01191-6.**

**✅ Fleckenstein, Braunstein & Walter 2025** — *running*: long (3-min) intervals accumulate more
time >90% VO2max than intensified 30-s intervals. Fleckenstein D, Braunstein H, Walter N. *Faster
intervals, faster recoveries — intensified short VO2max running intervals are inferior to
traditional long intervals in terms of time spent above 90% VO2max.* Front Sports Act Living.
2025;6:1507957. **PMID 39835194 · DOI 10.3389/fspor.2024.1507957.**

**✅ Rønnestad & Hansen 2016** — *cycling, opposite result*: 30-s intervals induced more time ≥90%
VO2peak than longer intervals. Rønnestad BR, Hansen J. *Optimizing Interval Training at Power Output
Associated With Peak Oxygen Uptake in Well-Trained Cyclists.* J Strength Cond Res. 2016;30(4):
999–1006. **PMID 23942167 · DOI 10.1519/JSC.0b013e3182a73e8a.** *(Often mis-cited as 2013 = epub.)*

**✅ Rønnestad et al. 2020** — *cycling*: short (30/15 s) beat effort-matched long (5-min) intervals
over 3 weeks (+4.7% 20-min power) in elite cyclists. Rønnestad BR, Hansen J, Nygaard H, Lundby C.
*Superior performance improvements in elite cyclists following short-interval vs effort-matched
long-interval training.* Scand J Med Sci Sports. 2020;30(5):849–857.
**PMID 31977120 · DOI 10.1111/sms.13627.**

**✅ Almquist et al. 2020** — effort-matched acute systemic/muscular responses favor short intervals.
Almquist NW, Nygaard H, Vegge G, Hammarström D, Ellefsen S, Rønnestad BR. *Systemic and muscular
responses to effort-matched short intervals and long intervals in elite cyclists.* Scand J Med Sci
Sports. 2020;30(7):1140–1150. **PMID 32267032 · DOI 10.1111/sms.13672.**

**✅ Rønnestad et al. 2021** — microcycle shock-block: short intervals → superior adaptations.
Rønnestad BR, Øfsteng SJ, Zambolin F, Raastad T, Hammarström D. *Superior Physiological Adaptations
After a Microcycle of Short Intervals Versus Long Intervals in Cyclists.* Int J Sports Physiol
Perform. 2021;16(10):1432–1438. **PMID 33735833 · DOI 10.1123/ijspp.2020-0647.**

> **Caveat on the cycling short-interval body of work (Rønnestad 2016/2020/2021 + Almquist 2020):**
> the short-interval superiority comes chiefly from a **single research group**, and its adaptation
> claims are challenged by effort-matched work: when **total work duration** is matched, the
> advantage reportedly disappears (attributed to a Seiler-group study — **unpublished /
> secondary-source, low evidence tier, not cited as fact**). Present short-interval superiority as a
> *lab-consistent but not independently settled* finding, not a cycling consensus. See
> `vo2max-intervals.md`.

**❌ "Effort-matched cycling replication, no difference" (Seiler group)** — **NOT VERIFIABLE as a
primary source.** Referenced only via secondary/coaching sources as an unpublished master's thesis
(~30 cyclists, VO2max ~64, total-work-matched, no short-vs-long difference). Used only to *temper*
overconfidence in the short-interval side; **do not cite as established evidence.**

---

## Distribution / periodization philosophy

**✅ Seiler 2024** — "long game, not epic workouts"; HIIT is not an acute-maximization problem;
polarized training as a context-dependent principle. Peer-reviewed Perspective (open access). Seiler
S. *It's about the long game, not epic workouts: unpacking HIIT for endurance athletes.* Appl
Physiol Nutr Metab. 2024;49(11):1585–1599. **PMID 39079169 · DOI 10.1139/apnm-2024-0012.**

**✅ Sun, Yu et al. 2025** — review of training-intensity-distribution models: **no single model
universally superior**; adapt to sport/phase/athlete. *(Use for the "distribution is context-
dependent" point — it does NOT claim frequency > distribution.)* Sun Q, Yu Y, Cui J, Lin S, Wang X,
Zhou T. *Recent advances in training intensity distribution theory for cyclic endurance sports.*
Front Physiol. 2025;16:1657892. **PMID 41169886 · DOI 10.3389/fphys.2025.1657892.**

**❌ "Yu et al. 2025" (frequency > distribution)** — **NOT FOUND.** No PubMed paper with Yu as first
author making this specific claim could be located. **Do not cite.** The nearest real paper
(Sun/Yu 2025, above) does not support "frequency outweighs distribution." Ground the frequency point
in Seiler 2024 instead, and label it a heuristic, not a quantified finding.

---

## Notes on verification method

All ✅ identifiers were read from PubMed record pages and cross-checked against DOI resolvers by
independent verification agents on 2026-07-20. Where a claim's *number* is widely repeated but not
verbatim in the source abstract, it is marked ⚠️ and the reference docs say so inline. No identifier
in this list was fabricated; the one unlocatable citation is explicitly marked ❌.