Marathon myths, checked

Marathon advice is full of confident rules. Some come from popular books, some from podcasts and social media, and some from product marketing. This page checks 22 of them against the research reviewed for this site.

The verdicts are about specific claims, not about whole books or their authors. Many of the books mentioned here get the main message right, and several of the claims below are versions that spread beyond what the original author wrote. Where a claim has its own page, the claim links to it.

The verdicts

Claim	Verdict	What the evidence shows
Most running should be easy	Supported	Faster marathoners mostly differ by running more easy volume.
80/20 polarized training beats pyramidal	Contradicted	Two meta-analyses found no time-trial difference.
Zone 2 is the best stimulus for mitochondria, fat burning or VO2max	Overstated	Not better than higher intensities; Zone 2 alone does not maximize VO2max.
Double threshold at fixed lactate targets	Untested	Not tested as a method; fixed mmol targets don’t transfer between people.
MAF “180 minus age” marks your aerobic threshold	Untested	Even its author concedes it isn’t tied to the lactate threshold.
Your max heart rate is 220 minus age	Overstated	Underestimates in older adults; typically off by about 11 beats.
The weekly 10% rule keeps you injury-free	Not supported	No benefit in a trial; single long-run spikes matter more (long-run rule).
A 16-mile long-run cap is enough (Hansons-style “cumulative fatigue”)	Untested	Longer longest runs go with faster times (Doherty 2020).
Cut intensity in the taper	Not supported	Cut volume; keep intensity and frequency.
Planned fuelling of about 60 g carbohydrate an hour helps recreational runners	Supported	About 11 minutes faster in the only marathon trial. See also hitting the wall.
Drink at every station; sodium prevents low blood sodium	Contradicted	Overdrinking is the cause. Drinking to thirst is supported.
Super shoes make everyone 4% faster	Overstated	About 1% at recreational pace; some runners get worse.
Strength training improves running economy	Supported	Small to moderate gains, mostly from heavy lifting (Llanos-Lagos 2024).
Strength training prevents running injuries	Not supported	No reduction unless the programme is supervised (Wu 2024).
Everyone should run at 180 steps a minute	Not supported	Cadence is only weakly linked to economy (Van Hooren 2024).
Switch your foot strike or go minimal	Not supported	Not recommended for uninjured runners (Anderson 2020).
Run-walk gives a similar time with less discomfort	Partly supported	One trial (Hottenrott 2016).
Keto or fat adaptation improves endurance	Contradicted	Worse economy at race pace (Burke 2017; Burke 2021).
“Train low” on carbohydrate improves performance	Not supported	No benefit in a meta-analysis (Gejl and Nybo 2021).
Plan training around menstrual-cycle phase	Not supported	At most a trivial phase effect (McNulty 2020).
Women should never train fasted and need a 30-minute protein window (as popularized)	Overstated	Lacks robust support (Matkin-Hussey 2026).
“Brain endurance training” makes you race faster	Overstated	Mental-fatigue effect near zero after bias correction (Holgado).
Rest completely the week after a marathon	Not supported	Easy activity from 48 hours didn’t slow recovery (Martínez-Navarro 2021).

The pattern

The supported claims are mostly unglamorous: run mostly easy, build long runs gradually, fuel and drink sensibly on race day, and keep intensity in the taper. The claims that fail tend to promise a precise edge, such as one intensity model, one heart-rate formula, one cadence, one diet or one shoe, for everyone. Where the evidence is weak, it is usually because nobody has run the trial, not because the idea has been proven wrong. “Untested” is not the same as “false”.

What we don’t know

• Most marathon evidence is observational, male-skewed and based on short time trials. Few trials use a marathon as the outcome.
• Several claims rest on a single trial, including the fuelling trial and the run-walk trial.
• Untested claims could still turn out to work. Double threshold for amateurs and the Hansons long-run cap have simply not been compared head to head with the alternatives.
• The review behind this page had a limited search budget, so some authors and topics, such as stretching, warm-ups and altitude, were not examined.
• The women’s nutrition review examined claims matching themes some authors promote, but it could not be confirmed that it names any specific author.

Sources

• Doherty et al. (2020). Longest training run and marathon performance.
• Llanos-Lagos et al. (2024). Meta-analysis of strength training and running economy.
• Wu et al. (2024). Meta-analysis of exercise programmes for preventing running injuries.
• Van Hooren et al. (2024). Biomechanics, cadence and running economy.
• Anderson et al. (2020). Changing foot strike in uninjured runners.
• Hottenrott et al. (2016). Randomized trial of run-walk vs continuous running.
• Burke et al. (2017). Ketogenic diet and race-walking performance in elite athletes.
• Burke et al. (2021). Ketogenic diet, economy and carbohydrate restoration in elite race walkers.
• Gejl and Nybo (2021). Meta-analysis of periodized carbohydrate restriction.
• McNulty et al. (2020). Menstrual cycle phase and exercise performance.
• Matkin-Hussey et al. (2026). Review of nutrition claims aimed at active women on social media.
• Holgado et al. Mental fatigue and endurance performance, corrected for bias.
• Martínez-Navarro et al. (2021). Active recovery after a marathon.