Niggles often warn of a bigger injury
Low confidence
A niggle is a small ache that lingers between runs but does not stop you yet. In semi-pro footballers, carrying a minor complaint raised the risk of an injury that cost training time in the following week about 3.6-fold, and a moderate one about 6.9-fold. Runners have not been studied this way, so the size of the effect for runners is unknown.
Why it works
A plausible explanation is that a niggle marks early tissue stress, and running through it lets that stress build. No study has measured this in runners.
What it means in practice
Treat a lingering low-grade ache as worth noticing, not background noise. In the app, log niggles separately from sharp, acute pain so the pattern is easy to see. Easing off intensity or mileage for a few days is a sensible precaution, but no study has tested how much or how long.
The evidence
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Non-time-loss injuries, the 'niggles' players train through, were useful in identifying players at increased risk of a time-loss injury. A minor complaint raised time-loss injury risk over the next 7 days by 3.6 times; a moderate complaint raised it by 6.9 times. The signal showed good predictive power (22.0 to 41.8%; AUC 0.73 to 0.83), and among compliant responders 28% of players each week, on average, reported a complaint that did not stop training or match play.
n=218
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Across 7 focus groups, 31 recreational runners described injury as a 9-level continuum: running smooth, discomfort, niggle, twinge, persisting niggle, non-responding niggle, short-term injury, long-term injury, and career-ending injury. They placed each level in four descriptor categories: physical, outcome (effect on running and daily life), psychological, and management. Runners preferred to self-manage lower-level injuries, many did not count a niggle as an injury, and they came to see themselves as "injured" once they lost that autonomy and needed external professional help. Lacey and colleagues propose the continuum as a tool for injury surveillance and risk-factor research, and as a framework for teaching runners to self-manage lower-level symptoms.
n=31
Why we call confidence low
Low: the only quantitative evidence is from football. Whalan 2019 followed 218 semi-professional footballers weekly for a season and found that a minor complaint raised the risk of a time-loss injury in the following 7 days about 3.6-fold, and a moderate complaint about 6.9-fold. In runners, Lacey 2023's focus groups (31 recreational runners) show runners often keep training through low-level symptoms, but they describe perceptions rather than measure what happens next. No prospective runner study has tested whether niggles predict later injury.
Where it applies
Adult runners, recreational through trained.
Does not apply to: normal post-workout muscle soreness that resolves within 48-72 hours.
Plans that respect this
Plans that scored well on the rubric measures informed by this claim.
- 10-Week Advanced 10k Training (5 days)
- 10-Week Run a Faster 10k (3 days)
- 10-Week Run a Faster 10k (4 days)
- 10-Week Run a Faster 10k (5 days)
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- 10-Week Run a Faster Half Marathon (3 days)
- 10-Week Run a Faster Half Marathon (4 days)
- 10-Week Run a Faster Half Marathon (5 days)
- 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)
Last reviewed Oct 14, 2026. See how we score.