An issue that surfaces regularly when players experience a totally new synthetic turf concept, is the claim that the surface is either too slippery or too rough to find their footing. Finding the right balance is complicated and involves much more than just the yarn or the carpet concept.
A former top hockey player who was asked to comment on the newly introduced dry-turf concept he had just played on claimed that the surface was too rough. Dutch football players interviewed after their game on a new non-filled or mineral filled synthetic turf concept indicated that the surface was too slippery. Both interview sessions were part of data-gathering exercises that are compulsory for any company wanting to introduce a new synthetic turf surface to the Dutch market. Alarmed, the Dutch FA (KNVB) even commissioned the Department of Movement Sciences of the Free University of Amsterdam, to establish exactly what their members were talking about. “We video-taped several games on these new concepts and had the footage analysed by a scientist. He noticed a high incidence-rate when the surface was damp with dew or wet from the rain,” says Patrick Balemans of the KNVB. Incidents were grouped in one of ten different categories, ranging from managing to remain upright to falling down completely, either with or without having the ball, and whether this happened while running, shooting, passing or receiving. “We noticed an incident every few minutes, something we find unacceptable. However, the type of incident and incident rate differed between the various non-filled and mineral-filled concepts as well as between the various surfaces in each category, making it even more difficult to find common ground.”
Not necessarily a turf issue
Incorrect or excessive player-surface interaction is not exclusive to newly developed synthetic turf surfaces. As recently as 2019, Professors Paul Fleming and Steph Forrester of Loughborough University advocated that a new mechanistic approach is needed for studying the traction forces generated during boot-surface interactions on third-generation synthetic turf, this despite the concept having been around for almost 30 years. “Lots of research was traditionally empirical, which is good for benchmarking but doesn’t explain the why,” Forrester says when asked why such an essential issue is still being studied 30 years since its inception. In their study ‘Traction forces generated during studded boot-surface interactions on third-generation artificial turf: A novel mechanistic perspective,’ Fleming and Forrester identified 39 variables as directly affecting the traction response. This included the player’s body mass, movement and intensity to technique, the location, synthetic turf system dynamics, to the design of the third-generation turf surface, its condition and history, to the design of the boots the player is wearing. “Slipping at tackling is often an issue of a player not getting it right. A solution to this problem might be found in the design of the shoe,” she adds, thereby indicating that it is not always the synthetic turf system designers who are to blame. Forrester points out that, despite the fact rubber infilled synthetic turf surfaces have been widely rolled out over the past 30 years, “there is still scope to improve synthetic turf boots for use on rubber infilled synthetic turf surfaces.”
New testing apparatuses
The discrepancy between what players experience and what system designers had in mind can also be attributed to new insights that continually come to light. One of these will now result in FIFA adopting an adjusted Advanced Artificial Athlete (AAA) test in the upcoming release of the Handbook of Test Methods. In the paper ‘Comparison of player perceptions to mechanical measurements of third generation synthetic turf football surface,’ published early last year, Fleming and Forrester, together with David Cole and Jon Roberts (both also from Loughborough University), David James (testing institute Labosport), Mickael Benetti, Katharina Wistel and Johsan Billingham (all from FIFA) point out that “the AAA produces a short dynamic impact curve of < 50 ms, with a measured peak force in the range 2–3 kN to pass the FIFA standard requirements. In contrast, during running on third generation turf a typical foot-strike peaks at around 1–2 kN and lasts about 250 ms. Vertical forces of 3 kN have, however, been recorded underfoot during landing from a simulated header. Furthermore, the AAA test foot generally resembles the shape and area of the human heel, in contrast to peak player contact forces which typically occur with the whole- or fore-foot in contact with the surface.”
Continual point of attention
While the authors used only third generation synthetic turf surfaces for their study, the AAA-test as well as the Rotational Resistance Test (RRT) are also updated in the interest of the development of non-filled turf systems. Although none of these systems has currently been approved by FIFA, there is still the consensus that this concept will be the way forward. For that reason, Loughborough University, together with TenCate Grass, has initiated a PhD study to further delve into the issue of how non-filled synthetic turf responds to player interactions, including the characteristics associated with shear/traction related (horizontal) player/mechanical test movements and relevant aspects of (vertical) impacts.
Regarding dry-turf for hockey, the situation is a bit different. Elsewhere in this issue, you can find an article on the latest dry-turf developments. Yet, the first dry-turf surface that was installed for official testing according to FIH criteria has a completely different carpet configuration than the current standard. Pending a clear indication of the way forward for this type of surface, perhaps we should keep something else in mind. “Once we adopted watered synthetic turf hockey surfaces, players started to slide and dive, which wasn’t really the case on sand-dressed surfaces,” the Facilities and Quality Programme Manager of the International Hockey Federation (FIH), Alastair Cox, recently remarked. “World Rugby, on the other hand, had to deal with the fear of carpet burns when they adopted synthetic turf. Both the FIH and World Rugby now allow for the wearing of undergarments to accommodate the players.” Cox’s rationalisation is straight forward: “As things evolve, we recognise that it is often more than just the carpet.”
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