Pitch perfect
Studies suggest there us no difference between injury incidence rates on grass and synthetic surfaces, rather it is their quality and not material that counts.
It is 4 years since I completed my work to deliver, commission and handover Oriam, Scotland’s sports performance centre, to move my life and family to the other side of the world. I do, however, still like to connect with the facility which is largely through news stories that use the large, indoor synthetic field as their hero image.
This is no surprise: the indoor pitch was the focal point of the project. The McLeish report, which was the catalyst for Oriam being built, had found Scotland needed more indoor training facilities. In the years since Oriam opened, the indoor pitch has been well used; it has hosted Victory Shield games, the national football and rugby tams, reserve grade football matches along with school events including CBBC’s ‘can you kick it?’. The usage, measured in hours, goes well beyond what could be accommodated on a natural turf field. On the face of it then, a good investment; so why is it that synthetic fields still seem to polarise opinion within sporting circles?
The main concerns around synthetic fields can be described as falling into two main categories; that they result in more injuries when compared to natural turf and that they are detrimental to the environment. To explore these questions we need to look at how synthetic fields are built. Layers sit beneath the green carpet on which you run that are not uniform across installations and will depend on the budget allocated to the project. The depth and composition of these sub-layers have an impact on the quality of the finished product, its longevity and the amount of use it can withstand. For example, synthetic surfaces often but not always have a shock pad layer, an installation that should reduce impact forces when players run, jump and land. The quality of the materials used to build the layers beneath the shock pad can also vary. This, as we will see, is why comparisons between synthetic and turf fields is not easy.
Concerns at the professional levels of football that synthetic fields are the cause of more injuries when compared to natural turf is not borne out in the research; studies have looked at injury incidence rates on grass and synthetic and found there to be no difference. This does not stop coaches and medical practitioners at the top level of football recoomending that their players do not train nor play on synthetic fields.
It is worth pausing to consider the challenges in conducting such large scale studies. Players with an injury history around the knee and ankle often report greater swelling, soreness and loss of movement after training on synthetic fields compared to grass (I can attest to this as I am one of them). these incidences are not classified as an injury because the player is usually able to continue with their routine with only small modifications in training practises. The issues are described as ‘niggles’, common parlance within football circles, and are the topic of research conducted by Dr Matt Whalan, physiotherapist to the Australian Socceroos team. As an example, injury classification systems used by clubs may require players to miss at least two consecutive sessions for an injury to be logged and included in any subsequent analysis.
Dr. Whalan found that the presence of a niggle increased the risk of suffering a more significant time-loss injury by 3-6 times depending on the severity of the complaint. Dr Whalan also told us “Over 25% of players will have a niggle each week that doesn’t stop them playing, but negatively impacts on their performance, whilst 68% of time loss injuries were preceded by a niggle in the previous week.”
This is a problem with studies that aim to report the rates of injury incidences between clubs, leagues and countries: there needs to be a universally accepted and validated method of classifying injuries so that a level of certainty around its cause can be established. For example, it is impossible to say exactly what has caused an injury that was not the result of direct contact. The myriad factors that may have contributed include, but are not limited to: age, previous injuries, training volume, training intensity, hydration, sleep quality, familial circumstances, stress… The list could go on and on and certainly includes the quality and type of surface. Isolating one factor above the others, however, is difficult.
Rather than polarising the debate between natural and synthetic fields, looking at the quality of the field may be a better starting point. Ante Covic knows this well. In a professional career spanning 20 years, he spent eight seasons in Sweden with Hammarby and Effsborg, training and playing on both natural and synthetic fields. On his time at Hammarby (2002-2007) Ante reflected: "most players who were playing for clubs that could maintain natural grass fields did not like or enjoy playing on synthetic, not because of injury concerns but because the early synthetic field installations played poorly, they had very shorthorn with lots of black rubber pellets which resulted in the ball bobbling constantly.”
Time change, though: when he joined Effsborg, advances had been made in how synthetic fields were constructed and maintained, so that, by 2009, “the increase in quality of synthetic surfaces was massive. Longer blade yarn, underlay and better maintenance regimes made it quite enjoyable. For three seasons we trained on a synthetic pitch daily and played all our games on it. When a game was to be played on grass we would have a few training sessions on that surface to adjust.” A recent study which looked at perceptions of injury risk among players competing in the Womens UEFA European Championships seemed to echo Ante’s views, in that the quality rather than the type of surface was the main concern held by players.
Given players do not play and train on one pitch, perhaps changing surfaces may contribute to injury? John Currie, Head of Sport Science at Celtic FC, an old colleague of mine at Heart of Midlothian FC and experienced in the English Premier League with Sunderland FC, explains the differences he has experienced in natural grass fields. Of the Non Camp he recalls: “The grass was cut to 15mm, 5mm less than the training fields at Real Madrid, something that allows a much faster style of football yet markedly different from the stadia in the Scottish Premier league, where Celtic FC ply their domestic trade. As a comparator, the length of the yarn used on synthetic fields that is recommended for Football is 50mm. John also noted: “Where grass pitches are soft because of excessive rain and poor drainage, synthetic fields can be a welcome relief. However, this is really dependant on the player and their perceptions.”
This makes sense given that in professional circles the use of synthetic fields for match play and training is still not the norm, at least in the UK and Australia. Players who have experience of training and playing on synthetic fields and who not suffer any negative effects, real or imagined, are unlikely to be perturbed by using them. It may also help explain why teams who install a synthetic field do not report more injuries. Indeed, the majority of young players in Scotland and Australia will undertake much of their development training an competing on synthetic surfaces, yet we have not see an epidemic of lower body injuries as a result.
The concept of how a change in surface may be a factor in injury incidence is worth exploring more closely. Clubs invest time and effort in testing their pitches, both natural grass and synthetic, for factors such as firmness and traction.; ground keepers will perform these tests in spots around the field to understand how it is playing and also how best to schedule maintenance regimes. I have worked with this type of data over multiple seasons, and in facilities where there are numerous fields, and have seen differences within and between grass fields that would likely be greater than between grass and synthetic surfaces. For example, players who train and play on natural turf may still encounter large differences between the conditions underfoot over the course of a season in their training base includes more than one field of play. Players will contest half the matches they play on a different surface to that which they train and play their home games on.; despite this we rarely hear that an injury sustained on an away teams field was the result of differences between the two natural grass fields.
The difference, however, could be greater than that experienced between grass and synthetic. There may also be differences between the grass pitch that players train on and that which they play their home games on. Training fields have to withstand much more activity than a match venue, may be constructed to a lower standard and, in some instances, are looked after by a different grounds team. Two years ago the Sydney Roosters, an Australian Ruby League team, suffered a spate of knee injuries that were linked to the change in surface between the wicket and the outfield ares of the pitch; they play (but do not train) on an oval that hosts Cricket in the summer and Rugby/AFL in the Winter.
The technology associated with synthetic fields is improving all the time and FIFA have recently published guidelines on how to maintain these surfaces along with how best to dispose of them when they are decommissioned. One of the main environmental concerns is around the impact that the infill, small micro-plastics, has on the environment when they get washed into waterways as well as the associated heat gain with synthetic surfaces. To combat the issues of micro-plastics, drainage systems around the field should include either gross pollutant trapdoor similar waste collection baskets to stop the plastic infill making their way into the water system.
This is important as synthetic fields are impervious to water and so overland flows during heavy rain fall will collect at least some of the plastic infill. The impervious nature of synthetic fields means they add to heat gain, more important now than ever as we strive to reduce global warming. Using organic infill in synthetic fields can help reduce heat gain and us less of an issue to the water system. However, it is more expensive than traditional plastic infill to install and maintain. As this technology becomes more widely adopted, the cost will decrease. Globally, however, the environmental impact of synthetic fields is likely to remain a concern.
Building a new field is complicated and the most complex components are hidden from view. the installation of a new field is unlikely to lave much change from a six figure budget, irrespective of whether it is natural turf or a synthetic surface. Budget cuts can be made however user groups are more likely to complain if these are made to the dimensions, floodlights or equipment (goals, dug outs and the like). This means that savings are likely to be made in areas that are hidden from view yet more likely to have a long term negative impact on playability and perhaps environmental impact. As well as the capital cost, there are ongoing maintenance costs to factor in; for synthetic fields the maintenance costs are considerably lower whilst accommodating greater usage, upwards of 50 hours per week compared to 12-15 for natural grass. More bookings and more revenue. With increased usage an reduced operational costs it is not difficult to see why so many clubs, councils and sporting organisations are electing to install synthetic fields.
At first glance, the island of green that football is played on can seem pretty uniform, especially when viewed from the stands. In reality, it is anything but. Its construction can differ in many ways with as much variance between different grass fields as between natural turf and synthetic surfaces. The devil is in the detail..
Whilst there are still unanswered questions relating to synthetic surfaces and injury, these questions apply in equal measure to the differences between different natural turf fields and should be considered in future large scale studies that look to investigate the topic. There is also work to be done in understanding the environmental impact of the infill used in synthetic field installations and how this can be decommissioned in a way that is kind, or at least kinder, to the environment.
The bigger challenge for football is ensuring that as many people of all ages can access a green rectangle throughout their life to enjoy the game and develop their skills; it is this that will foster the development of future professionals whilst nurturing a love of the game amongst the masses that lasts a lifetime. To this end, synthetic fields may well be the answer.
This article was first published in Nutmeg, the Scottish Football Periodical, in September 2021.
