Long runs are essential for the marathon
High confidence
Runs longer than about 90 minutes teach your body things shorter, faster sessions cannot. Over those hours you learn to burn fuel steadily and keep your legs from breaking down. Most marathon plans build the long run up to 2.5 to 3 hours or more.
Why it works
Long, steady running sits below your threshold (the pace where easy effort tips into hard). Held for hours, that effort teaches your body to stretch its fuel further. It grows new small blood vessels to feed the muscles. And it toughens the tendons and connective tissue that get pounded over long distances.
What it means in practice
In a solid marathon plan, the long run builds to a peak of 2.5 to 3.5 hours, whatever your pace. A plan that caps the long run at 90 minutes or less for marathon prep is worth questioning. For a half-marathon, long runs of 90 to 120 minutes do the job.
The evidence
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Of 675 first-time marathoners who finished the study, 64 (9.5%) sustained a major injury that stopped a race start or finish; another 332 (49.2%) reported a minor injury affecting training or performance. Prior half-marathon experience predicted lower injury risk (multivariable OR 0.40, 95% CI 0.22-0.76, p=0.005), as did longer training runs (OR 0.87 per unit, 95% CI 0.81-0.94, p<0.001). Running four or more times a week carried higher risk than fewer sessions (RR 1.36, 95% CI 1.13-1.63, p=0.001), while age and sex made no significant difference. Injuries were self-reported, so treat the effect sizes as suggestive rather than definitive.
n=720
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Resilience, the ability to preserve running economy and neuromuscular function late in prolonged exercise, is a trainable performance attribute distinct from VO2max, lactate threshold, or fresh-state economy. Runners matched on VO2max and 10K performance still differ in how well they hold economy deep into a run: those who regularly train long runs over 90 minutes show only a 3.1% rise in oxygen cost across a 90-minute effort at ~80% VO2max, versus 6.0% in less-accustomed runners. Higher training volume, regular long runs, and strength work all track with better durability. Specificity applies too, so building resilience at race pace likely requires training at race pace, including long aerobic intervals such as the 15 × 1000m sets elite marathoners run; as a narrative review of a recent concept, its specific prescriptions still run ahead of the RCT evidence.
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Across their first seven years of systematic training, the world-class Kenyans ran more total distance than either Spanish group (P<0.001, d≥1.35). They also logged more tempo runs and short intervals (P<0.001, d≥1.38), but not more long intervals or races. Easy running was the largest single component for every group as a share of total distance, and the two Spanish tiers separated mainly on easy-run volume. The design is retrospective and observational on 55 elite runners, so it distinguishes world-class from national training patterns without showing that the extra tempo and short-interval work caused the gap.
n=55
Why we call confidence high
Toresdahl 2023, tracking NYC marathon training, found that runners who logged longer training runs had a lower injury risk on race day. Jones 2025 lays out the physiology behind that. And Casado 2019 shows how much elite runners lean on the long run in their own training.
Where it applies
Adult marathon and ultramarathon runners. It matters less for the half-marathon and shorter distances.
Does not apply to: 5K and 10K specialists where long-run benefit is more limited.
Plans that respect this
Plans that scored well on the rubric measures informed by this claim.
- 10-Week Run Your First 10k (3 days)
- 10-Week Run Your First 10k (4 days)
- 10-Week Run Your First Half Marathon (3 days)
- 10-Week Run Your First Half Marathon (4 days)
- 10-Week Sub-1:30 Half Marathon (4 days)
- 10-Week Sub-1:30 Half Marathon (5 days)
- 10-Week Sub-1:30 Half Marathon (6 days)
- 10-Week Sub-1:45 Half Marathon (4 days)
- 10-Week Sub-1:45 Half Marathon (5 days)
- 10-Week Sub-1:45 Half Marathon (6 days)
- 10-Week Sub-2 Half Marathon (3 days)
- 10-Week Sub-2 Half Marathon (4 days)
Last reviewed Apr 30, 2026. See how we score.