From synthetic turf to hardwood floors, the surfaces underfoot in athletic facilities have advanced by leaps and bounds over the past 25 years
The sports landscape of 2002 appears vastly different than the one witnessed in 1977. Indeed, the very foundations of competition, the surfaces on which games are played, have undergone steady change over the past 25 years.
So subtle, perhaps, has the surface evolution been that the casual observer of synthetic turf fields, hardwood floors and ice rinks and the like may not realize any change has taken place at all. But, to be sure, those in the increasingly competitive sports surfacing industries have kept close tabs. Ultimately, it's the participants who have benefited, as top-quality surfaces once reserved for elite athletes and athletic programs eventually found a broader marketplace. This country's athletic participation boom has coincided with a race among manufacturers to unveil the next revolutionary approach to accommodating a given sport without radically altering its play.
Natural Turf One athletic surface predates all others: the grass field. While grass is the most natural of all sports surfaces, it has benefited greatly from human intervention since 1977.
Back then, native soils comprised the vast majority of natural turf athletic fields, even at the professional level. Often exhibiting the high-compaction characteristics of clay and other sticky soils, these fields inhibited the vertical movement of water through their profiles. In other words, they tended to puddle, divot, smear and in the process do a poor job of preventing grass plants from being uprooted. Consequently, native-soil fields required considerable recovery times, limiting their use.
In 1977, the application of sand-based fields to fall-down sports such as football was considered experimental - and expensive. But the soil profile that helped golf courses handle tremendous amounts of water eventually came to be seen as one with similar benefits for more aggressive sports, as well. Given their high percolation rate through a root zone highly concentrated with sand, these fields proved to be not nearly as susceptible to water damage. Today's sand-based fields withstand up to three times as much play and even enhance the quality of play. Their popularity has been fueled by a shortage of fields in the wake of the decades-long sports participation surge, particularly among girls and women, and by heightened athlete expectations regarding the performance of fields. For example, sand-based fields are more tolerant of today's lower mowing heights dictated by the participants in ballroll sports such as soccer and field hockey.
Still relatively scarce at the high school level, sand-based fields involve considerable installation costs, as well as accelerated irrigation and fertilization programs to keep pace with the fields' ability to rapidly percolate water. (On the other hand, their resistance to compaction translates into a less-frequent need for aeration.) However, sand-based fields have gained a foothold in higher-profile venues. One estimate puts the growth in use of these fields at the professional level from 5 percent in 1977 to around 80 percent today.
On fields in which slow percolation rates raise standing-water concerns, the advent of laser leveling within the past five years has greatly facilitated the next-best drainage alternative: runoff. The goal is to have water migrate from the crown of a field toward its sidelines without puddling along the way. Tractors armed with a laser eye indicate to maintenance staff where a field is high or low, and whether those areas need to be cut down or filled in. A properly laser-leveled field may exhibit a drainage-friendly tolerance of a quarter-inch in its finished grade.
Both native-soil and sand-based fields have benefited from increasingly sophisticated subsurface drainage systems, and in-ground irrigation has evolved from the days when saucer-shaped steel sprinkler caps dotted a field to the point where automated retractable sprinkler heads are virtually invisible. Technology has even advanced the installation of sod, which in 1977 entailed the piecing together of 16-by-24-inch slabs. Today, sod cut in 4-by-100-foot rolls allows for fewer seams and quicker stabilization and playability of the field.
Additional innovations have included the introduction of both synthetic and biodegradable fibers and mesh backings as a means to stabilize and strengthen the root zones of natural grass fields. Systems have been designed as "hybrids" of natural and synthetic turf, with permanent synthetic fibers keeping fields playable in areas where real grass blades have been displaced. Other systems use plastic trays, measuring several square feet, in which to grow natural grass. The trays, which are perforated to allow for drainage and airflow, can be rotated to evenly distribute a field's wear and tear, or completely replaced as needed with backup trays of fresh grass.
Perhaps the greatest change involving natural grass athletic fields over the past 25 years is the recognition of their care as a true full-time profession, as evidenced by the increasing number of colleges and universities offering degrees in turf management and by the formation in 1981 and subsequent growth of the Sports Turf Managers Association.
Synthetic Turf In existence for more than 10 years by 1977, synthetic turf would undergo some of its most significant changes during the next quarter-century.
As with natural turf, drainage has always been a primary concern among users of synthetic fields, particularly during the late '70s. To encourage runoff, synthetic turf fields of the time commonly exhibited crowns placing the center axis of a given field as much as 3 feet higher than its sidelines. Some percolation was accomplished by drilling holes into the closed-cell foam padding sandwiched between the blanket of turf fibers and a concrete or asphalt substrate. However, with the advent of porous asphalt, greatly improved percolation rates have made severe crowning of synthetic turf fields far less common, or necessary, today. A football field in 2002 may require a crown of only 6 inches, mainly to avoid the optical illusion created by perfectly flat fields, which appear slightly dished. This has allowed ball-roll sports such as soccer and field hockey to more readily embrace synthetics.
Another innovation that contributed to more consistent ball roll on synthetic turf involved the fibers themselves. Fields once exhibited an obvious grain, with the turf's ribbon-like fibers positioned so that their flat sides gave a uniform appearance to at least one side of the field (usually the one facing the press box). Football coaches were even known to run plays against this grain, or into the fiber tips, so their ball carriers had better traction to make cuts. Then, manufacturers began manipulating the nylon ribbons with moisture and heat to set irregular kinks in each fiber. This process essentially made entire fields uniform in appearance and performance, with a ball rolling the same distance regardless of direction.
Stitched seams also contributed to more consistent play on synthetic turf. In 1977, seams were joined by gluing each section of turf to a strip of polyester tape. While this tape didn't represent a tremendous stumbling block, the field was nonetheless raised slightly and noticeably stiffer at its taped seams, located every 15 feet or so. By stitching the two sections together using a sewing apparatus rolled along the field on wheels, the turf remained a perfectly even plane.
By the late 1980s, a cushioning alternative emerged. The new layer combined ground rubber and a polyurethane adhesive, and was laid with an asphalt spreader over a bed of crushed and compacted stone. Though the rubber layer tended to be less expensive and last twice as long as its closed-cell predecessor (which after 10 or more years lost resilience as gas escaped the millions of tiny bubbles within the pad), it often produced a firmer surface.
What many observers might consider the most recent - and revolutionary - challenge to the synthetic turf status quo actually traces its roots back to the 1980s. Still, field systems featuring longer fibers and an infill of sand or sand and crumb rubber (one early entrepreneur even identified cork as an infill material) have received the bulk of the industry's attention within the past five years. To the casual observer, synthetic turf systems that incorporate infill may come closest to resembling natural turf, with their longer fibers free to move in any number of directions, even while stabilizing a bed of loose material at their base. Time will tell whether their popularity will continue to increase among athletes and facility operators.
Hardwood Floors A hardwood gym floor from 1977 may not look any different than one assembled in 2002, but there have been significant changes in what lies beneath the maple surface. An explosion of subsurface options and configurations has led today's manufacturers to offer some 30 variations of wood flooring systems each, five times what was marketed 25 years ago.
Back then, consumers were confronted with two basic options: a floating floor or an anchored floor. Floating floors featured tongue-and-groove boards mechanically fastened to a subfloor material such as plywood, which then floated unfastened on a lower layer of shock-absorbing material, typically foam, which like the plywood was also free-floating. This configuration, while producing proper performance characteristics, left the floor susceptible to buckling in the event of excessive humidity or, worse, a water leak. The layers of an anchored floor, meanwhile, were pinned or clipped snugly to the substrate, providing a lively but ultimately fatiguing surface for sports participants.
Today, the benefits of both are found in a hybrid, called the restrained floating floor, which uses metal pins, channels, straps or other mechanical fasteners to loosely fasten the subfloor system to the concrete beneath it.
In a pin system, the foam and plywood layers are anchored to the concrete, even as the maple floorboards are fastened to the plywood. The heads of the pins are sufficiently recessed in the plywood so that when the foam is compressed, the maple floorboards don't bottom out on the unmoving pinheads. In a channel system, 2-by-4-inch boards rest freely on a layer of cushioning within upturned U-shaped metal channels, which are anchored to the concrete in a parallel grid. A plywood subfloor is then nailed to the 2-by-4 "sleeper" boards, or maple is nailed directly to the sleepers in perpendicular fashion. In a system utilizing metal straps, the straps wrap around padded and evenly spaced 2-by-3-inch sleepers, with the ends of each strap attached to the substrate on opposite sides of the sleeper. The straps are held in place at the top of the boards by notches, which are cut deep enough to allow vertical movement of the sleepers once they are fastened to the plywood subfloor or maple floorboards above.
Each of these systems provides the floor with enough stability to deter buckling during moisture-induced expansion and contraction of the system, while also controlling the amount of vertical deflection the floor imparts upon athletes.
Wood floor performance relating to such factors as shock absorption and ball bounce has received increased attention from manufacturers over the years. Hence, the widening array of subfloor options. For example, strips of foam, as opposed to one solid sheet, can effectively soften a floor. Perhaps quarter-inch foam is replaced by 2-by-3 inch rubber pads that are 3/8 -of-an-inch thick. Instead of two layers of solid plywood subfloor, the top layer can be specified as plywood strips, allowing air movement underneath the surface.
In addition, water-based urethane finishes have gained in popularity since 1977, when mostly oil-modified urethanes were used. Both provide equally durable protection, according to wood flooring experts. However, water-based finishes typically contain smaller concentrations of volatile organic compounds (deemed a health risk by the Environmental Protection Agency during the '90s), dry twice as fast and are resistant to yellowing over time.
Synthetic Floors The past 25 years have also brought more choice to the synthetic gym floor market.
One system to emerge from Europe, which lacks the maple wood resources of the United States, uses prefabricated mats made of recycled tire rubber. These mats, which are available in a variety of thicknesses based on varying performance specifications, are coated with a poured layer of urethane to create a durable, seamless playing surface.
Another innovation has introduced the benefits of rubber to poured-in-place urethane floors. While never capable of equaling the softness of rubber, urethane is now available in a formulation containing 25 percent finely ground rubber for application in self-leveling lifts. Pouring the first three lifts of a half-inch floor with this mixture, topped with a solid lift of urethane, is an option designed to combine the shock absorbency of rubber with the stability of fully bonded urethane.
But even as additives have been introduced to urethane floors since 1977, their worst components have been weeded out. The elimination of mercury and lead from poured-in-place urethane has made disposal of these floors less of an environmental burden. Formulations have also stabilized to the point where a floor is less likely to revert to a gummy state in the event moisture wicks up through the concrete substrate beneath it.
Injection-molded polypropylene tiles came indoors from primarily outdoor residential court applications during the mid-'80s. What these snap-together modular tiles brought with them was unprecedented multipurpose functionality and immunity to moisture damage. A popular choice as a volleyball surface, tiles also proved they could stand up to basketball and inline hockey competition, as well.
The synthetic surface to most closely match hardwood floors in appearance within the past 25 years takes the form of resilient vinyl sheet goods. In addition to presenting consumers with a multitude of color combinations, vinyl floors can be formulated to feature the wood-grain look and texture of maple and other hardwoods. Vinyl floors, as well as those incorporating vulcanized rubber, also allow for a wide selection of thicknesses and performance specifications, sometimes incorporating multiple layers of materials engineered to provide users with a comfortable and responsive playing surface. Even the seams inherent to the application of sheet goods have virtually disappeared, thanks to advanced heat-welding techniques.
Tracks By 1977, the future of outdoor track surfaces was in sight. While most institutions with tracks still maintained cinder surfaces, and a smaller percentage ran on rubberized asphalt, polyurethane systems were beginning to pop up on the campuses of a few Division I universities and private colleges.
Today, synthetic tracks dominate from Olympic Stadiums to high schools, and it's not uncommon to find these all-weather surfaces installed at middle schools, too. The reason is a proliferation of affordable polyurethane and latex formulations that have made even rubberized asphalt economically obsolete. Not that tracks have abandoned their past completely. Asphalt still comprises the foundation of the new generation of all-weather tracks (porous asphalt is used to handle excessive precipitation in the Northwest), and a recycled rubber component provides the lower layers of these newer poured surfaces with their resiliency.
In addition to poured polyurethane and latex tracks, facility managers can also choose an embossed vulcanized rubber surface available in a variety of thicknesses on rolls of varying widths and lengths.
The result of these innovations are running surfaces that are more uniform than cinders, which often varied from one track to another and sometimes even along the same track, depending on how well it was maintained. Loose cinders produced a softer, slower surface; packed cinders, a track that was hard on athletes' joints. Wet or dry, cinders could also be slippery if not compacted properly. Synthetics essentially removed these variables, allowing runners to train longer on a urethane or latex track due to its superior energy return and consistent traction, even in rainy conditions.
Synthetics also brightened the track world by introducing color to the oval. The blacks and grays of the cinder and asphalt days have given way to popular reds, blues and greens, as well as other color options.
Tennis Courts Tennis was in the midst of near-decade-long growth spurt in 1977, and manufacturers flooded the market with, by one count, more than 100 brand names of synthetic surfaces suitable for the sport. But those banking on the popularity boom to continue indefinitely were soon disappointed.
What has remained consistent over the past quarter-century is that the majority of Americans play their tennis outdoors on hard courts. These all-weather courts, which comprise an estimated 80 percent of all tennis courts in the United States, typically amount to a rough asphalt base (concrete is used primarily in the Southwest) that is coated with a smooth, albeit sand-textured acrylic. Acrylic technology applied to these courts has evolved to the point where today's court surfaces are stronger, brighter and easier to repair. By the late '70s, the process of patching courts had abandoned the use of relatively crude asphalt-emulsion products in favor of more durable acrylic resins capable of holding sand.
This period also saw the popularization of a cushioned acrylic material spread thinly between the asphalt or concrete base and the acrylic surface, a development that continues to pay dividends today as one means by which tennis centers, particularly those in for-pay indoor settings, cater to the sport's aging player demographic. While no noticeable change in the speed of play results from this surface cushioning, it is seen as more comfortable for players.
However, as tennis boomers of the late '70s reach their 50s and 60s, speed of play has become a concern. With today's surface formulations, manufacturers can incorporate sand of varying concentrations and sizes to give each court its own feel. As the concentration of sand or the size of sand particles increase, the court becomes slower. Thus, tennis becomes more accessible to the aging player or younger players of average skill. Even tennis coaches at the collegiate level have been known to prefer slower courts, since they allow student-athletes to be trained to handle a wide variety of shots, not just 140-mile-per-hour serves.
As the sport matures, tennis courts appear more conservative today than in 1977. The red-and-green surfaces popular then have given way to all-green or two-tone green courts. That said, radical colors such as purple have found a niche among the sport's younger players.
Ice Sheets Few surfaces have witnessed greater changes to the way they are installed and maintained than the ice sheet. Certainly, no surface is as susceptible to a greater number of mechanical and atmospheric variables.
Computerized control systems employing infrared cameras to monitor ice surface temperature began gaining popularity in the late '80s and became the recognized standard within the next decade. These tools, which allowed rink systems to automatically react to changes in ice temperature, replaced the old method of manually adjusting the refrigeration process using thermostat readings and mechanical switches.
Refrigeration system components have evolved, as well. Screw compressors emerged as a popular alternative to reciprocating compressors in the 1990s, the same time plate-and-frame chillers became recognized as a smaller, equally efficient alternative to the traditional shell-and-tube chiller. Refrigerants have come and gone, as dictated by environmentally driven government policy. The result is that chlorine-based refrigerants such as Freon have been steadily phased out in favor of less-harmful compounds such as ammonia, which traces its refrigeration roots back to the late 1800s.
The very water used to flood rinks at the loftiest levels of competition has improved since 1977, thanks to more widespread use of a purification process that filters out minerals and organic matter. Used in the old Chicago Stadium in 1971 and in Toronto's Maple Leaf Gardens before the end of that decade, the process has within the past 15 years become standard at professional and collegiate facilities where local water is of poor quality. This purified water results in clearer, denser ice that is faster for players and easier to control for rink operators.
Perhaps the greatest impact on ice quality over the past quarter-century involves a rink component not physically linked to the refrigeration cycle: the dessicant dehumidifier. Utilizing the same silica gel found in the packaging of shoes and other dry goods, these machines remove moisture from the arena atmosphere that, if left unchecked, would condense on the coldest surface available: the ice sheet. Heat released during this condensation is enough to melt the ice surface.
The sun's radiant energy has always presented additional heat-load concerns, even within roofed arenas. But widespread use of low-emissivity ceilings, whose reflective silver prevents radiant heat from reaching the ice surface, didn't emerge until the mid-'80s. Combined with advances in refrigeration and dehumidification, these ceilings have contributed to ice rinks exhibiting 30 percent greater efficiency today than in 1977, by one expert's estimate. This newfound efficiency has been critical to the steady migration of ice sports into the warm, humid climes of the southern United States.
Ice has also come a long way visually. Sheets used for the highest levels of competition in 1977 were not only plain in appearance by today's standards, they often looked patchy and uneven, as well. In the past, ice treated paint as a pollutant, gradually pushing it toward the surface, and the paint tended to attract radiant heat. Paint used on rinks in 2002 is more easily suspended within the ice and actually reflects radiant heat. Ice sheets today feature a stark white surface, brighter blue lines and red face-off circles, not to mention colorful team logos and splashy advertising graphics.
Changes to sports surfaces over the past 25 years have included both the subtle and dramatic. It's arguable that each one has succeeded in advancing the cause of participants and the efficiency of facility operations.
No surface is perfect, as one industry insider puts it, but imperfection is what drives innovation. As shortcomings in certain surfaces are gradually exposed, alternatives emerge, and the constant tweaking of sports surfaces by biologists, chemists and engineers has resulted in a quarter-century of progress toward greater surface performance, utility, safety and aesthetics.