NEW DEVELOPMENTS IN URETHANES FOR TRACK SURFACES YIELD RECORD RUN TIMES AND REDUCE THE RISK OF TRAINING INJURIES WHILE REMOVING MERCURY TOXICITY
By Thomas Garrett, Ph.D.
R&D Director, Athletic Polymer Systems, Inc.
While advances in nutrition, training, shoes, equipment and coaching methodology have contributed to setting track records in the past few decades. One previously overlooked component has recently garnered attention as a means to improve track times — track surface itself. Although synthetic surfaces first appeared on running tracks more than 40 years ago, few really significant improvements have since been made. However, with the recent introduction of advanced urethanes for track surfaces, collegiate coaches and athletics directors are now benefiting from the performance payoffs — both in short and long distances — made possible by these technological improvements.
On the other hand, a renewed focus on synthetic track surfaces has unveiled a previously unknown threat, that of mercury toxicity. However, the same technical improvements that have yielded faster running times have also managed to produce surfaces that lack any mercury whatsoever.
Improving Speed and Endurance, While Avoiding Liability
At the highest levels of track and field, fractions of seconds make the difference between winning and losing. For this reason, even choosing the right track surface now ranks as a critical decision for any campus administrator or athletics director.
By some estimates, the average track coach will oversee the installation of one to two track surfaces in a career. While the technical and design details can be complex and require a consultant, one basic consideration is the issue of short-track performance vs. long distance training.
"The longer the race, the more punishing the track surface on the student-athlete," observes Steve McBride, University of Oregon Associate Athletics Director for internal operations and a past project manager for Hayward Field-the legendary venue for the USA championships, NCAA championships and the Prefontaine Classic. "In a sprint, it might be fine to have a hard surface that returns all the energy back to the athletes quickly so they can move to the next step, but in distance races you need a surface that is more forgiving. The trick is to find a material and design that works for everybody, even infield runways where acceleration and stopping are important."
"We needed both a high performance venue and a surface we could train on," adds Tom Heinonen, three-time NCAA coach of the Year and eight-time Pacific-10 Conference Coach of the Year, now serving his 26th year as head coach for the womenís track team at Oregon. "The harder a track, the faster you can run on it until the spikes wonít go in anymore. But, the harder it is, the more people get hurt on it. Youíve got to be able to train on it too, unless you want an empty stadium reserved only for events and meets."
Many schools and colleges also must weigh durability into the equation for finding the right track surface. For instance, because Hayward Field is open to the public, and the elements, 24-hours a day, the resurfacing material also has to be durable enough to handle the expected wear-and tear without compromising its performance characteristics.
"From the athleteís point of view, we needed top performance without unnecessary injury, but from the maintenance point of view, we need the surface to last as long as possible at an acceptable price point," says McBride.
In addition, the issue of mercury liability is now also affecting the choice of track surfaces. A potent neurotoxin capable of damaging the central nervous system of adults and impairing neurological development in fetuses and children, mercury has been used as a manufacturing catalyst in polyurethane-based running track surfaces since the 1970s. Mercury traditionally delayed the curing process to make the track easier to install — a cost-saving measure that has no performance benefit. However, influenced by rising litigation, stiffer federal regulations and more clearly defined health risks from mercury exposure, colleges are now specifying track surfaces that are built without its use.
Advanced Urethanes that meet All Needs
Building upon the proprietary urethane research of some of the most famous poured-in-place athletics surfaces, chemical engineers have now developed improved polyurethane with a dynamic response optimized for an athleteís gait, with the energy return on the same time scale as that of a naturally occurring footfall. This patented polyurethane athletics surface redirects the energy otherwise release as heat, into a rebound force that enhances performance and improves track times.
Modern polyurethane also install easier than previous artificial track surfaces. Unlike rubber sheet, structural sprays or other materials which must be torn out before refurbishing the track surface, this advanced urethane is simply poured over an existing surface — automatically leveling itís self, and filling in any existing surface cracks, dips or grooves. Each subsequent urethane pouring ups the performance factor, since each new layer adds to those beneath it.
In contrast to rubber surfaces, which shrink and harden, advanced urethanes remain unaffected by hot or cold temperatures and wonít retain water, greatly reducing the need for maintenance.
Perhaps most importantly, though, one manufacturer has developed a 100 percent mercury-free urethane formula for track surfaces. The removal of mercury has actually helped increase the dynamic performance of the filler material, while greatly reducing liability for campus administration.
Advanced Urethane Track Surfaces Prove Faster
"We were one of the first schools to put in a synthetic track under Bill Bowermanís leadership in the late Ď60ís," says Oregonís McBride. "As the technology has increased and the budget allowed, weíve always tried to get the best surface available."
Since the fall 2000 installation of an advanced urethane track surface at Hayward Field, the university has recorded a number of new track records according to USA Track & Field — the national governing body for track and field, long-distance running and race waking — records set at Hayward Field in 2001 include — the collegiate and American records for the womenís 3,000-meter steeple chase at 9:49.73 (set by Elizabeth Jackson of Brigham Young University); a new womenís 3,000-meter steeple chase record at 9:49.41 (later set by Lisa Nye of Nike); and the American junior 100-meter record at 10.08 (a tie, set by Justin Gatlin of Tennessee). At the 2002 Perfontaine Classic, Alan Webb broke Jim Ryunís high school mile record with a 3:53 effort, and four 100-meter dash times under 10-seconds occurred.
"Hayward Fieldís current surface lets us run fast without beating up our athletes," adds Heinonen. "Thatís what every coach wants: a fast surface for meets thatís good for training, too. Itís a great track."
Susquehanna University, a Division III competitor in Selingsgrove, Pennsylvania, also recently installed a six-lane 200-meter indoor track using advanced urethane materials.
"Eighteen MAC records were set on the surface the first time we held a Middle Atlantic Conference (MAC) meet at the facility," says Jim Taylor, head menís track coach at Susquehanna, who has 10 MAC conference outdoor titles in his 24 years with the university. "The facility enhanced as the athletesí times, whether they won or finished fifth."
Some of the sprinters like harder surfaces and some of the distance runners like softer surfaces, but we couldnít have one lane soft and the other hard," continues Taylor. "We had to put down one surface that was beneficial to everybody. Now, thereís nothing comparable to our 200-meter indoor track in the conference."