REF-1312 · Kluitenberg et al., 2016 · Journal of Science and Medicine in Sport · Paper · PubMed

Does running harder raise a beginner's injury risk?

In 1696 novices a harder-feeling previous week went with more injuries (HR 1.28 per unit of mean RPE, our reading) but not with first pain; observational, not a guideline. B+.

Main caveat: Observational, time-varying exposures. Reasons for weekly differences are unknown; the authors flag the volume result as likely confounded.
moderate evidenceMeasured on non-athletes and recreational people

Kluitenberg and colleagues asked whether training factors in the week before each session predict running injury in novices.

Registrants of the 2013 Start to Run programme (Dutch Athletics Federation; 6 weeks, two or three runs a week, one supervised, goal a 20-min run without breaks) aged 18-65 were invited; 1772 completed the baseline questionnaire and 1696 at least one weekly diary.

For every session the diary recorded minutes, RPE (6-20) and any pain; an injury was pain in one body part of the lower extremity or back, attributed to running, that restricted running for at least three consecutive sessions (one week).

Running volume, frequency and mean RPE were computed over the 7 days before each session and entered as time-varying predictors in Cox models with minutes of running as the time scale. Of 185 injured runners, 26 were injured in the first week (no prior-week data), leaving 159.

Higher mean intensity in the previous week went with higher injury risk (multivariable HR 1.28, 95% CI 1.18-1.40); more than 60 min in the previous week went with lower risk than under 30 min (HR 0.41, 0.20-0.86); running three times a week tended to be riskier than twice (HR 1.42, 0.97-2.08).

In a sensitivity analysis with the first report of pain as the outcome, volume showed the same protective pattern but intensity was not associated (HR 1.02, 0.97-1.08).

The authors conclude that running more than 60 min at lower intensity was least injurious, call the volume finding contrary to expectation and "presumably the result of other factors", and say the results should not be used plainly as a guideline.

The companion paper (same 1696 runners) found 10.9% injured during the programme, with higher age, higher BMI, previous musculoskeletal complaints not attributed to sport and no previous running experience as risk factors (abstract; hazard ratios not given there).

Our reading: the one novice cohort that ties a harder previous week to injury; an association with felt effort, in a low-intensity programme, that did not carry over to first pain.

Protocol

Who: n = 1696 novice runners with at least one diary (of 7660 registrants invited and 1772 who completed baseline); 1332 women (78.5%), age 43.3 ± 10.0 years, BMI 25.5 ± 4.0, no running experience 1023 (60.3%).
Programme: Start to Run 2013 (March or September), 6 weeks, two to three runs a week, one supervised by a licensed athletics trainer; about 15 min of warm-up and cool-down (walking, stretching, relaxation).
Diary: weekly online, per session: planned and completed sessions, running minutes, RPE 6-20, pain in the lower extremities or back (body chart), whether the session was completed despite pain; e-mail and phone reminders.
Injury: musculoskeletal pain in a single body part of the lower extremity or back, attributed to running, restricting running (speed, distance or duration) for at least three consecutive sessions (one week); muscle soreness and blisters excluded.
Exposures (time-varying, previous 7 days, current session excluded): total running volume (min; categorised by quartile — under 30, 30-45, 45-60, over 60 min — because proportional hazards failed for the continuous form), number of sessions (under 2, 2, 3, over 3) and mean RPE (continuous).
Analysis: extended Cox regression, minutes of running as the time scale; univariable then multivariable; sensitivity analysis with first pain as the outcome; Schoenfeld residuals; at least 10 injuries per predictor; personal characteristics not included (treated as effect modifiers; strata too small to stratify). R 3.1.3, survival 2.38.1. Ethics: University Medical Center Groningen, no. 2012/350.
Funding and interests: funded by a grant of ZON-MW (50-50305-98-12001); the Dutch Athletics Federation gave access to Start to Run participants (acknowledgements; not named as a funder). No conflict-of-interest statement appears in the article text read.

Key Results

Previous-7-day predictorInjury: univariable HR (95% CI)Injury: multivariable HR (95% CI)First pain: multivariable HR (95% CI)
Volume under 30 min1 (reference)1 (reference)1 (reference)
Volume 30-45 min0.73 (0.48-1.13)0.65 (0.40-1.06)0.63 (0.50-0.79)
Volume 45-60 min0.71 (0.42-1.18)0.56 (0.31-1.04)0.45 (0.33-0.61)
Volume over 60 min0.52 (0.29-0.93), p = 0.0280.41 (0.20-0.86), p = 0.0180.38 (0.27-0.53)
Mean intensity (RPE)1.29 (1.18-1.41), p < 0.0011.28 (1.18-1.40), p < 0.0011.02 (0.97-1.08), p = 0.432
Under 2 sessions1.16 (0.74-1.81)0.92 (0.56-1.50)0.85 (0.67-1.08)
2 sessions1 (reference)1 (reference)1 (reference)
3 sessions1.20 (0.84-1.72)1.42 (0.97-2.08), p = 0.0751.18 (0.98-1.42)
Over 3 sessions1.71 (0.51-5.71)2.27 (0.64-8.01)0.89 (0.47-1.67)
Exposure: 18,706 sessions and 6732.5 h of running; 3632 sessions fell in the first week and had no prior-week data. Mean intensity 12.1 ± 1.5 on the RPE scale.
The intensity hazard ratio's unit is not stated; mean RPE entered as a continuous variable, so it reads as per point on the 6-20 scale (our reading).
Companion (Kluitenberg 2015, abstract): 10.9% of 1696 runners sustained an injury during the programme (injury hampering running for three consecutive sessions); in multivariable Cox regression higher age, higher BMI, previous musculoskeletal complaints not attributed to sport and no previous running experience were related to injury.
Numbers that do not add up: the authors write that the first-pain sensitivity analysis "showed a similar pattern" to the injury analysis; for volume it did, but intensity — the headline finding — was not associated with first pain (univariable 1.03, 0.98-1.09; multivariable 1.02, 0.97-1.08). The session counts do add up: 3830 + 4068 + 2998 + 4178 + 3632 = 18,706 (our arithmetic).

Mechanisms

Measured: a higher prior-week mean RPE went with injury, and a larger prior-week volume with fewer injuries and less first pain, over minutes of running.
Authors' interpretation: novices should not run every session at too high an intensity. The volume result is unexpected and presumably due to other factors — for instance, people who pick up running easily may both run more and get injured less; it is not a green light to start above 60 min a week. Reverse causation (complaints leading to shorter sessions) was examined with the first-pain analysis, which kept the volume pattern.
Inference: RPE is felt effort. A runner whose legs are already sore, or who is less fit, rates the same session harder, so "harder week → injury" may partly mean "struggling runner → injury". Intensity did not predict first pain, which fits neither a pure "hard running causes damage" nor a pure "pain raises RPE" story cleanly.
Inference: in a run-walk programme at mean RPE 12, "higher intensity" means running the easy sessions harder, not adding intervals; the finding agrees with the base's practice of keeping a beginner's runs conversational (SYNTH-75) more than it tests intensity-first programming.

Practical Application

Does running harder raise a beginner's injury risk? In 1696 novices a harder-feeling previous week went with more injuries (HR 1.28 per unit of mean RPE, our reading) but not with first pain; observational, not a guideline. B+.
Keep a beginner's runs easy (B+, observational; consistent with the base's practice): conversational effort, in line with SYNTH-75's "everything else stays easy enough to speak in full sentences". A run that feels hard to a novice is a reason to slow down or walk, not a training target.
Do not read "more minutes, fewer injuries" as advice: the authors call it presumably confounded; the base's step rule — no single run far beyond the past month's longest (REF-1102) — still governs volume.
Risk markers for a novice (companion, from the abstract): older age, higher BMI, earlier non-sport musculoskeletal complaints and no running experience — reasons for a slower ramp (practice), not for a different order.
Hold it beside the trials: progressing hard running after an 8-week easy base injured no more recreational runners than progressing volume (REF-1290, A-, wide CI); this cohort's signal is in true novices, from felt effort, without a comparison group. Neither settles intensity's role; both argue for small steps.

Limitations

Observational, time-varying exposures. Reasons for weekly differences are unknown; the authors flag the volume result as likely confounded.
Few events. 159 analysable injuries; 26 early injuries had to be excluded because no prior week existed.
No adjustment for personal characteristics. Deliberate (treated as effect modifiers), but it leaves age, BMI and experience unaccounted for in these models.
Self-reported diary data, felt intensity rather than speed or heart rate, no diagnoses; three in four participants women; a 6-week programme.
Companion read from the abstract; its hazard ratios were not available.
Funding and interests: ZON-MW grant 50-50305-98-12001; no conflict statement in the article text read.
How this entry was checked and changed
Why this level

large prospective cohort (rubric B+), read from the full text (publisher version in the Utrecht University repository); not higher because only 159 injuries could be analysed, exposures are self-reported diary values, personal characteristics were deliberately left out of the models, and the volume finding is open to reverse causation and confounding that the authors themselves raise. The companion (risk factors, same cohort) carries B+ from its abstract

Full text (checked 2026-10-27)
1696 participants completed weekly diaries on running exposure and injuries during a 6-week running program; N = 1772 completed the baseline questionnaire, of N = 7660 registrants (full text)
185 of the included participants sustained a running-related injury; 26 injuries occurred in the first 7 days, so 159 runners were included in the analyses (full text)
Higher intensity was associated with injury in the univariable (HR 1.29; 95% CI 1.18–1.41) and multivariable analyses (HR 1.28; 95% CI 1.18–1.40) (full text)
Running more than 60 min in the previous 7 days: univariable HR 0.52 (95% CI 0.29–0.93), multivariable HR 0.41 (95% CI 0.20–0.86) (full text)
Running three times per week vs two: HR 1.42; 95% CI 0.97–2.08 (full text)
First pain, intensity: univariable 1.03 (0.98–1.09), multivariable 1.02 (0.97–1.08), p 0.432 (full text)
18,706 training sessions with a summed running duration of 6732.5 h; mean training intensity 12.1 ± 1.5 on the RPE scale (full text)
The NLstart2run study was funded by a grant of ZON-MW (50-50305-98-12001); registered as NTR3676 (full text)