Executive Summary
Published in the American Journal of Sports Medicine in 2019, this study from the Kerlan-Jobe Institute analyzed four consecutive seasons of injury data across Major League Soccer — one of the more rigorous professional-league surveillance studies comparing artificial turf and natural grass. Using MLS’s electronic health record injury tracking system, researchers set out to test whether injury rates on artificial turf were “noninferior” (a formal statistical standard, not just “similar”) to natural grass at the elite professional level.
Key Findings
- Overall injury rate on artificial turf was noninferior to natural grass — the study’s primary hypothesis was supported across four seasons of professional match data.
- Foot injuries and forefoot injuries specifically were also noninferior on artificial turf.
- No statistically significant difference was found in knee injury rates between the two surfaces.
- Ankle injury rate was found to be higher on artificial turf — the one injury category where a statistically significant difference favored natural grass.
- No other injury subgroup showed a statistically significant difference between surfaces.
- The study’s own stated conclusion: turf meeting the performance standard studied is “a viable alternative to natural grass in elite-level soccer competition.”
Important Limitations
- This is a professional, elite-level dataset — MLS fields are professionally maintained at a resourcing level not available to most schools or municipalities, which limits how directly the findings generalize to lower-budget or less-maintained fields of either surface type.
- The specific turf systems studied were not broken down by manufacturer, infill type, or installation age within this four-year window, so it cannot isolate which specific turf technologies drove the results.
- The elevated ankle injury finding is isolated to one specific injury category — it should not be read as evidence of broadly higher injury risk, since the overall and most individual injury-category comparisons showed no significant difference or favored turf.
- As with other surveillance-based research, this study shows association between surface and injury rate; it doesn’t isolate every possible confounding factor (playing style, team-specific medical care, schedule density).
Why This Matters
This is one of the more methodologically rigorous professional-level comparisons in the literature — four full seasons, formal noninferiority testing, and a real-world elite competitive environment rather than a lab setting. The overall result is a genuinely favorable data point for well-built, professionally maintained turf systems. The one exception — ankle injury — is consistent with a pattern that shows up elsewhere in this Research Library (see Gould et al. 2023): foot and ankle injury risk is the area where the literature most consistently flags a difference, even when broader injury measures look comparable or favorable.
Act Global Perspective
This study reinforces two things we think are worth saying plainly. First, well-maintained, professional-grade turf can perform at or above the level of natural grass across most injury categories — this isn’t a marginal or hypothetical claim, it’s what four seasons of MLS data show. Second, the recurring foot/ankle signal across multiple independent studies in our library is a real pattern worth taking seriously, not an outlier to explain away. That’s why traction and release characteristics — measured through rotational resistance testing — remain one of the core categories Act Global tests and reports on for every system, rather than treating overall injury parity as the end of the conversation.
Related Resources
- Lower Extremity Injury Rates on Artificial Turf vs. Natural Grass — Review of Gould et al. 2023
- Incidence of Football Injuries on Artificial Turf vs. Grass — Review of Kuitunen et al. 2023
- Rotational Resistance Explained — Traction and Lower-Extremity Injury Risk
Access the Original Study
This review is Act Global’s independent summary of publicly available peer-reviewed research, prepared for educational purposes. Act Global does not host or reproduce the original article. Read the full study directly from the publisher:
- Calloway SP, Hardin DM, Crawford MD, Hardin JM, Lemak LJ, Giza E, Forsythe B, Lu Y, Patel BH, Osbahr DC, Gerhardt MB, Mandelbaum BR, Baldwin WW. “Injury Surveillance in Major League Soccer: A 4-Year Comparison of Injury on Natural Grass Versus Artificial Turf Field.” American Journal of Sports Medicine, 47(10):2279–2286, 2019. DOI: 10.1177/0363546519860522
This is an Act Global Research Review — an independent interpretation of publicly available peer-reviewed research prepared for educational purposes only. It does not constitute medical, legal, or engineering advice.
