REF-1644 · Mitchell et al., 2025 · Sports Biomechanics, Vol. · Paper · PubMed

Running on a softer surface lowered peak tibial acceleration (SMD −0.8, 95% CI −1.42 to −0.18) but showed no significant difference in peak vertical ground reaction force, loading rate or ground contact time

A meta-analysis of overground running on hard against soft surfaces (25 studies, n = 492; 22 pooled, n = 392); the lower injury risk is the authors' inference from tibial acceleration, not a measured outcome

Main caveat: No risk-of-bias assessment in the abstract; study quality unknown.
moderate evidenceMeasured on a mixed groupRead from the abstract only

Mitchell and colleagues asked what the compliance of the running surface does to overground running biomechanics, given that surfaces are often blamed for running injuries.

Following the PRISMA protocols statement, they searched CINAHL, EMBASE and EBSCO with search terms for running on overground surfaces combined with biomechanical measures (kinematics, tibial acceleration, force and pressure).

After de-duplication and screening, 25 articles with 492 participants met the criteria, and 22 of them (392 participants) entered random-effects meta-analysis. On softer surfaces, peak tibial acceleration was lower (SMD −0.8, 95% CI −1.42 to −0.18; Z = 2.51, P = 0.01).

Peak vertical ground reaction force, the loading rate and contact time with the ground did not differ significantly between hard and soft surfaces. Because higher peak tibial acceleration has been associated with tibial stress injury, the authors judge that running on softer surfaces to cut the impact on the tibia is "probably justified" to lower the risk of stress injuries.

Participants

25 articles, 492 participants in all; 22 articles and 392 participants in the pooled analyses.
Not in the abstract: the runners' level, age, sex, footwear and the size of each study.

Methods

Search: CINAHL, EMBASE and EBSCO; anchoring terms covered running and overground surfaces together with biomechanics, kinematics, tibial acceleration, force and pressure; the search date is not in the abstract.
Selection: de-duplication, title and abstract screening, then full-text review against inclusion criteria that the abstract does not list.
Analysis: random-effects meta-analysis, standardised mean differences.
Quality: no risk-of-bias or quality assessment reported in the abstract.
Not in the abstract: the surfaces compared, running speeds, heterogeneity and effect sizes for the outcomes that did not differ.

Key Results

Outcome, softer against harder surfacePooled result
Peak tibial accelerationlower on softer surfaces: SMD −0.8 (95% CI −1.42 to −0.18), Z = 2.51, P = 0.01
Peak vertical ground reaction forceno significant difference
Loading rateno significant difference
Ground contact timeno significant difference

Practical Application

A softer surface softened the shock at the shin; the force through the body showed no significant change. Pooled across studies, running on softer surfaces lowered peak tibial acceleration (SMD −0.8) while peak vertical ground reaction force, loading rate and contact time did not differ significantly. Moving some easy running to softer ground is a reasonable option for a runner worried about load on the shin bone; it has not been shown to prevent injury.
The injury step is the authors' inference. Peak tibial acceleration has been linked to tibial stress injury, so they call softer surfaces "probably justified"; injury was not among the pooled outcomes.
Inference, not tested here: a change of surface does not replace managing the load itself; in the base, a sudden jump in run length is the risk marker to watch (SYNTH-29), and bone stress injury is treated as a loading problem (REF-622).
Who decides: bone-like or worsening shin pain goes to a clinician before any surface experiment (SYNTH-94); the assistant does not diagnose.
Not settled by this design / not from this paper: whether softer surfaces lower injury rates, which surfaces were compared, whether the effect holds late in a long run, and whether uneven soft ground brings other risks (trail running has its own risk-factor evidence, REF-783).

Limitations

No risk-of-bias assessment in the abstract; study quality unknown.
Biomechanics only; injury was not an outcome, and tibial acceleration stands in for injury risk only through earlier associations.
Surfaces, speeds, footwear and runner characteristics are not in the abstract; "hard" and "soft" may cover different surfaces across studies.
Small studies on average (our reading: 492 participants across 25 articles); the effect of fatigue or of weeks of running on one surface is not addressed.
Written from the abstract and the PubMed record; full text not read.
How this entry was checked and changed
Why this level

risk of bias not read (abstract only; the abstract reports no risk-of-bias or quality assessment); the pooled outcomes are directly measured mechanics (tibial acceleration, ground reaction force, contact time), not markers, but injury was not among the pooled outcomes

Content correction 2026-11-07
2026-11-07: added from the abstract and the PubMed record; level B+ (meta-analysis; risk of bias not read, abstract only).