The relationship between ground conditions and injury: What level of evidence do we have?

Abstract

Objectives

To identify studies which address the relationship between ground conditions and injury, in a sporting context and to evaluate current practice and provide recommendations for future studies that measure ground conditions and injury risk.

Design

Systematic review.

Methods

A comprehensive search of electronic databases from the earliest records available until the end of 2011, and supplemental hand searching was conducted to identify relevant studies. A classification scale was used to rate the methodological quality of studies.

Results

79 potentially relevant articles were identified, and 27 met all inclusion criteria. They varied in methodological quality, with analytical observational studies the most common design, although four descriptive observational studies, considered to be of lower quality were also identified. Only five studies objectively measured ground conditions, and of studies that used subjective assessment, only one provided descriptors to explain their classifications. It appears that harder/drier grounds are associated with an increased injury risk but the presence of major limitations necessitates cautious interpretation of many key findings.

Conclusions

There is limited high quality evidence of the relationship between injury risk and ground conditions. Further research with high quality designs, and measurement of ground conditions are required to draw more definitive conclusions regarding this relationship.

Introduction

In an array of sports including cricket and the different codes of football, characteristics of ground conditions have been identified as a factor associated with injury risk.1, 2, 3, 4, 5, 6, 7 Ground hardness (the effect that the surface has on absorbing impact energy) and traction (the type of footing or grip a playing surface provides) have been cited as the two main surface characteristics related to injury, particularly the lower limb.⁸ Hardness is most highly correlated with soil moisture content and traction with grass cover.⁸ While studies investigating the relationship between ground conditions and injuries are evident in the sports medicine and international sports science literature,1, 2, 4, 5, 9, 10, 11 the range of approaches used to investigate this relationship have not previously been systematically and comprehensively examined. Accordingly, there are no standardised practices for the measurement of ground conditions, and this has resulted in an intuitive relationship, rather than a solid evidence base linking ground conditions and injury.1, 4, 12, 13

Orchard⁵ identified that there was a need to make use of, and further develop instruments to measure ground conditions, although as an initial step in advancing current practice, it seems appropriate to recognise and evaluate published studies. While two systematic reviews investigating injury and playing surfaces have been published recently, they have addressed the difference in injury rates on natural and artificial playing surfaces,¹⁴ and the incidence, nature and mechanisms of football injuries on natural turf compared to newer generation artificial turfs.¹⁵ This systematic review differs as it aims to identify and compare studies which address the association between ground conditions and injury, in a sporting context. More specifically, it describes the methodologies and assessment of ground conditions, and highlights the strengths and weaknesses of different approaches. Implications for understanding the relationship between ground conditions and injury risk, and considerations for improving the quality of ground measurement in future studies are discussed.