Chris Farhood
f6dd9dfc27
Modular cycling-training skill: periodization logic, workout design, and research-backed protocols that companion an Intervals.icu MCP server (the server owns all data + computed metrics; the skill owns knowledge + reasoning). Structure: - SKILL.md router + README (companion-to-MCP architecture, install steps) - references/: durability, mtb-xco-demands, strength-for-cyclists, vo2max-intervals, periodization, data-confounds, citations - assets/: base + build plan templates, durability field-test protocol Every quantitative claim carries an inline citation; citations.md is the single source of truth with PMID/DOI, each verified against PubMed on 2026-07-20. Notable honesty flags baked in: - VO2 rep-length: running (Fleckenstein 2025) vs cycling (Ronnestad) conflict documented rather than asserted; cycling evidence favors short intervals. - 'Yu et al. 2025' (frequency > distribution) could not be found; not cited. - Under-researched doses (durability, taper TSB, CTL ramp) flagged 'track response'. - HR-confound doc forbids naive decoupling<5% / RHR+5 rules. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01TqrhBhC3GEcKyaw8RTk8G6
72 lines
4.6 KiB
Markdown
72 lines
4.6 KiB
Markdown
# VO2max interval optimization
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**Load this doc when:** designing high-intensity interval sessions, choosing rep length or
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work:rest, or trying to rebuild sustained aerobic power.
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**Data/knowledge split:** MCP gives you the power/HR streams and interval stats to *check* whether a
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session did what you intended (was power sustained across reps?). This doc gives the *design logic*.
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---
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## The target: maximize time spent ≥90% VO2max
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The organizing principle of VO2max interval design is **accumulating time at or above 90% of
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VO2max** — that's the stimulus, not simply "going hard." Design sessions to spend the most quality
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minutes in that band that the athlete can repeat and recover from.
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## What a large meta-analysis found (dose-response)
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A systematic review with pairwise and network meta-analysis (**51 studies, 1,261 athletes**) found
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inverted-U dose-response relationships and identified an optimum around **~140 s work duration** and
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a **work-to-recovery ratio of ~0.85**, with ~3×/week over 3–6 weeks as an effective pattern (Yang,
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Wang & Guan 2025, *BMC Sports Sci Med Rehabil* 17(1):156; PMID 40605061;
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DOI 10.1186/s13102-025-01191-6).
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> **Caveat — modality.** This meta-analysis is weighted toward **running-based** HIIT. The ~140 s /
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> 0.85 optimum is a strong starting anchor, but see the cycling-specific conflict below before
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> treating "longer is better" as settled *for cyclists*.
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## ⚠️ Genuine conflict: rep length in cycling vs running
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The claim that **longer reps (3–5 min) accumulate more time ≥90% VO2max than 30/30s** is
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**supported in running but contradicted in cycling.** Do not present it as settled.
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| Modality | Finding | Source |
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| **Running** | 3-min intervals accumulated **more** time >90% VO2max (~328 s) than intensified 30-s intervals (~201 s), even with 30-s intensity raised | Fleckenstein, Braunstein & Walter 2025, *Front Sports Act Living* 6:1507957; PMID 39835194; DOI 10.3389/fspor.2024.1507957 |
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| **Cycling (acute)** | **30-s** work intervals induced **more** total time ≥90% VO2peak than longer intervals in well-trained cyclists — the opposite result | Rønnestad & Hansen 2016, *J Strength Cond Res* 30(4):999–1006; PMID 23942167; DOI 10.1519/JSC.0b013e3182a73e8a |
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| **Cycling (adaptation)** | Over 3 weeks, effort-matched **short** intervals (30/15 s) beat long (5-min) intervals — e.g. +4.7% 20-min power — in elite cyclists | Rønnestad, Hansen, Nygaard & Lundby 2020, *Scand J Med Sci Sports* 30(5):849–857; PMID 31977120; DOI 10.1111/sms.13627 |
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Reinforcing the cycling short-interval side: effort-matched acute responses (Almquist et al. 2020,
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PMID 32267032) and a microcycle shock-block (Rønnestad et al. 2021, PMID 33735833).
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**Why they might differ:** protocol construction differs (cycling short-interval work is typically
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30/15 s series to exhaustion; the running comparison used fixed-volume intensified 30-s reps),
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so part of the divergence may be design, not pure modality. Either way, **for cyclists the
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best-controlled evidence favors short 30/15-style intervals for accumulating time ≥90% VO2max**,
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which cuts against a blanket "bias toward longer reps."
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> ⚠️ **Under-researched — track individual response.** Optimal rep length for a *given cyclist* is
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> not resolved. Use the MCP interval/stream data to verify what actually keeps power ≥90%-effort
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> band across reps for this athlete, and let that — not a rule — drive the choice.
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## Practical prescription
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- **Default menu for cyclists** (bias to what the cycling evidence supports, then verify per rider):
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- **Short intervals:** 30/15 s (≈13 reps × 2–3 series) — strong for time ≥90% VO2max and
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adaptation in cyclists (Rønnestad 2020/2021).
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- **Longer intervals:** ~3–5 min reps at ~0.85 work:rest — the meta-analytic optimum region
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(Yang 2025); useful for **sustained** aerobic power and for riders who tolerate short intervals
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poorly. If rebuilding sustained power specifically, longer reps have a rationale — but this is
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a reasoned choice, not a proven superiority in cycling.
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- **Prescribe from power.** For MTB especially, HR lags and misleads (`mtb-xco-demands.md`,
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`data-confounds.md`).
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- **Verify the session worked:** pull the interval stats/streams from MCP and check power held near
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target across reps. Fading power = too much intensity or too little recovery; adjust work:rest.
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## Frequency vs distribution
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For *how often* to do hard sessions and how they fit the week/season, see `periodization.md` — the
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argument there (after Seiler 2024) is that the **long-term integration** of frequency, intensity,
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and duration matters more than chasing the acute maximum of any single session.
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