New study suggests mowing height has little influence on athlete speed

Synopsis

Athletic field groundskeepers are being pressured to mow turf too low by coaches who believe that their athletes can run faster on shorter cut grass. This practice leads to scalped fields and damaged turf.

A new study supports the author's contention that lower cutting heights do not increase athlete performance. The author proposes that mowing cool-season high school football fields at 2 inches should be a standard, justifiable procedure.

Background discussion

The athletic field is an unusual turfgrass situation. It is subjected to tremendous demands, undreamed of in a residential lawn setting. As explained by Goss and Cook (1993), the field must be able to “withstand intensive traffic under a range of climatic conditions.” To support this activity, the field must first be designed and constructed properly (Indyk, 1986). Realistic scheduling of the use of the field is also critical since an irresponsible overuse of living turfgrass will cause it to fail (Goss & Cook, 1993).

Equal in importance to initial development and subsequent scheduling of use is the implementation of sound maintenance programs. A poorly maintained field will be less able to sustain and recuperate from the wear and tear of sports activities. To endure these pressures turfgrass must be vigorous, dense, and deeply rooted.

Proper mowing practices play an integral role in realizing these objectives. Cockerham (1989) noted this relationship: The first and most apparent result of mowing on grass is that some of the photosynthetically active tissue is removed, reducing the plant food production capability.

A direct result of that removal is a reduction in root growth. Indeed, the relationship between mowing and root development was established early on in pioneering turfgrass research.

A 1961 experiment by Deal clearly showed the influence of higher mowing on Poa pratensis (Kentucky bluegrass) root quantity. The study compared two-inch and one-inch clipping heights and the resulting increase in rootmass associated with the higher cut.

That investigation, and others like it, contributed to the basic understandings contained in modern textbooks that instruct today’s turfgrass students. As explained by Hull (1996), a closely mowed turf will have a less developed root system and will be less wear tolerant. For the cool-season species used for sports turf, a cutting height above two inches will produce more rootmass than a height below two inches.

This root/shoot relationship becomes a critical factor on football fields where stress is the norm, and each management decision requires a careful consideration of consequences. Nowhere is the attention to this detail more important than in the maintenance of school athletic facilities. A poorly developed root system will be less able to access the water and nutrients needed for sustenance. This will require additional expenditures for the materials and labor needed to intensify fertilization and irrigation programs.

Clearly then, on facilities with limited resources, mistakes made in basic procedures are magnified, becoming not only wasteful but also difficult to rectify and potentially devastating.

Despite its merits, the proposal to raise football field mowing heights is met with resistance from coaches and players. Joe Casarella, the athletic director of the North Rockland Central School District, believes that most coaches are convinced lower heights of cut will enhance the athletes running performance. He also feels that these coaches are unaware that low mowing practices can negatively affect the playing field.

In an actual survey of football coaches “the overwhelming attitude of the coaches was that a higher cut turf would somehow impede the speed of the athletes (especially fast running backs) and thus somehow affect the outcome of the contest” (Caton, 1993).

This belief persists despite the lack of data to support it. In their athletic field cooperative extension publication, Goss and Cook (1993) wrote, “shorter mowing will provide a denser turf and a faster playing surface. Higher mowing will provide a slower surface but increased rooting depth.” It is unclear if the authors are referring to running speed or perhaps to ball roll. Canaway and Baker (1993) linked ball roll and mowing height.

It is accepted in the golf world that low cut heights are vital to playability, and superintendents manage turf for low heights. At a different (mowing) level, that holds true in other sports like soccer. Cockerham, Weston, and Kiesling (1995) constructed an apparatus for ball roll measurement in preparation for World Cup Soccer USA. Their device showed an increase in ball roll distance with a decrease in mowing height. However, there is nothing in the literature which links mowing height and foot speed.

The purpose of this study is to investigate the influence of clipping height on player speed and turfgrass quality on high school football fields.

In reviewing the literature, two key issues emerge which argue for the enhanced vigor associated with higher mowing on tight-budgeted school football fields. In light of the fact that there is no evidence that lower mowing increases foot speed, these fields should be mowed at two inches to promote safer fields of better playing quality and produce more pest-resistant turfgrass stands.

Harper, Morehouse, Waddington, & Buckley (1984) determined that a relationship exists between maintenance factors, surface and vegetative characteristics and field-related injuries in high school football. A follow up study demonstrated that greater shear resistance [traction] and lower impact values [more resilient field surface] were related to maintenance practices (Rogers, Waddington, & Harper, 1988). While traction and hardness will influence the sport participant’s perception of playing quality (Canaway & Baker, 1993), their greater importance clearly lies in field safety. Those practices, like proper mowing that contributes to improved turf cover, must be encouraged. Sifers and Beard (1996) acknowledged that “many impact-type injuries are related to varying degrees of surface hardness.” They also demonstrated that surface hardness is decreased with increasing heights of cut.

With limited budgets, the margin for error narrows, making it all the more important to adhere to sound mowing practices. A 1994 industry profile survey conducted by the Sports Turf Managers Association reported that the average cost per acre for the maintenance of professional sports facilities was $4,333. The figure for school fields was $658 per acre. Player safety, as well as enjoyment, needs to be considered in the efficient, effective and responsible management of school facilities.

An unpublished study by Gramckow (1966) showed no correlation between height of cut and foot speed. Conducted at Cal-Turf Nurseries in Camarillo, Calif., the study investigated characteristics of turfed areas such as impact energy absorption, shear strength, and wear tolerance in addition to the clipping height/running speed relationship. Running tests were performed on 100-yard tracks with eight tracks laid out on Bermudagrass, six on fescue and six on bluegrass for a total of 20 separate lanes. These lanes were cut at heights ranging from 1 inch to 3 inches in half-inch increments, with two additional lanes on the Bermuda grass at one-half inch each.

Ten high school football players were timed in a 100 yard sprint, running once on each track. Randomly selected, the track order was different for each runner. The 10 running times for each track were then averaged. The results showed no significant difference in sprint times. The conclusion was that cutting height had no appreciable affect on running speed.

Considering the location and time elapsed since the California study, it is apparent that further research is needed to verify the important inference that mowing below two inches does not enhance athletic performance.

New York study

The subjects for this study were male students from a more than 2,000 student high school serving more than 7,000 student suburban school district with a strong “tradition of excellence” in athletics. The 20-student sample in this study was selected from pre-existing, self-contained interscholastic sports teams for which the young players had successfully tried out. These teams were junior varsity and varsity football and cross country.

Athletes ranged in age from 13 to 18 and were selected by their respective coaches as being representative of a range of athletic abilities and running speed potential. The subjects were not told any details of the experiment. They were told only that their running speed would be tested and recorded in a series of 40-yard sprints, and they were encouraged to perform to the best of their abilities.

Players were separated into groups based on their respective teams. The subjects included seven from junior varsity football, seven from varsity and six from cross-country. All athletes wore cleated sports shoes except the cross country runners who wore a smooth-soled spikeless racing shoe.

The study was conducted at a time that corresponded to the athletes’ midseason so that they would possess their optimum physical conditioning and thereby minimize a fatigue factor that might influence sprint order results.

Results discussion

To test the hypothesis that there would be no difference in running speed on turfgrass mowed at the three different heights, the recorded sprint times were evaluated first to determine means and probability of the means being statistically significant.

The stability of individual sprint times is consistent with the hypothesis. There was no statistically significant difference in the comparison. When the sub-sample of only the 14 football players is examined, the data are equally supportive. The average time (rounded to the nearest tenth) for the 40-yard sprint of fourteen high school football players was 5.7 seconds at each clipping height.

Tables 1 and 2 (above) show the recorded times of these 14 athletes and clearly show their nearly identical performances in running the 40 yards regardless of mowing height.

When the data were examined in this sub-group manner, the cross country results seemed at first glance to indicate an association between height of cut and foot speed.

Table 3 (above) shows what appeared to be a gradual improvement in running times as the height was lowered with lane averages of 5.36 seconds at 3 inches, 5.33 at 2 inches and 5.26 at 1 inch.

The significance of these means was tested. The statistical technique reveals that the one-tenth of a second difference in times is easily within the realm of chance and is of no significance.

What may be worth noting, however, is the fact that 67 percent of the spikeless racing shoe cross country runners clocked their best time on the one-inch turf. Considering the fact that only a third of the cleated subjects recorded their best times at this height, as might be expected in a three-lane experiment design, the possible influence of shoe type and traction suggests further study. Indeed, it is possible that shoe type may have played a role in the origin of the belief in a clipping height/foot speed correlation.

Conclusion

This study was conducted to determine if lower cutting heights on high school football fields might be justified by a corresponding enhancement of athletic performance. No such relationship was observed.

Cool season turfgrasses, like Kentucky bluegrass, grow most of their roots in spring and fall. It is during these times, which coincide with the outdoor school sports season, that cutting height will have its greatest influence on root growth.

The results of this study argue for sensible mowing practices that provide safer athletic fields, promote better playing quality and produce a healthier, pest-resistant turf requiring fewer inputs. For these reasons, mowing cool-season high school football fields at 2 inches should be a standard, justifiable procedure.

References

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