Turf Management, Athletic-fieldConditions, and Injuries in High School

Football

J.C. Harper, C.A. Moorehouse, D.V.Waddington, and W.E. BuckleyPennsylvania State University

The wide range of turfgrass conditionsexisting on high school athletic fields

in Pennsylvania may reflect: i) proceduresused during construction, ii) past and cur-rent maintenance practices, iii) intensityof use, or iv) a combination of these fac-tors. The conditions of a playing field isnot only of aesthetic importance, but italso may affect play and player safety.

The prevention of athletic injuries, par-ticularly in a violent contact sport such asfootball, is of major concern to most edu-cational institutions. At college level,comparison of natural turf and artificialsurfaces in regard to football injuries hasreceived attention in recent years, but dif-ferences in quality of the turf on grassedfields has been a topic that has receivedonly minor attention.

Wilcox, Fox, and Beyer [Athl. J.45(10): 34, 1965] reported a pronouncedreduction in practice field injuries at onehigh school when practice sessions weremoved from a dry and heavily compactedarea to a field where the turf had beenadequately maintained. Of course, the re-duction in injuries may have been influ-enced by factors not under consideration.Also, conclusions based on data from asingle high school may not be valid forother schools. Sanderson [Athl. Purch. andFacil. 4 (5) 54,1979] stated that soil com-paction of athletic fields is a leading causeof football players' knee injuries. He ad-vocated a full maintenance program ofaerification, overseeding, fertilization,and weed control to provide a playingsurface that would tend to reduce the inci-dence and severity of injuries.

Well controlled studies of the effects ofturf management practices on the inci-dence of injuries in football are needed.The purposes of this study were i) to evalu-ate conditions of high school game and

•-,. ...

6 - Sports Turf Newsletter

practice fields and determine the relation-ship of field conditions to maintenanceprograms; ii) to determine if a relationshipexisted between field conditions and theincidence of field related injuries in highschool football, and iii) to provide profes-sional advice concerning turf manage-ment programs in an effort to improve thequality of high school football fields.

Experimental Procedure

Selection of Participants:In May, 1981, all high school athletic

trainers who were active members of thePennsylvania Athletic Trainers' Associa-tion were mailed a brief description of theproposed project. Trainers used the en-closed response card to indicate whethertheir school agreed to participate in thestudy and whether they were willing toprovide the required reports of injurythroughout the 1981 football season.

While most trainers expressed interest inthe study, only 12 schools were willing toparticipate. This sample came from vari-ous locations across the state and provided24 fields (12 game fields and 12 practicefields) for evaluation. Two of the schoolsdid not provide a complete record of inju-ries, so injury results and correlations in-volving injuries are based on the data from

10 schools. Field condition and mainte-nance comparisons reflect evaluations ofall 12 schools, however.

Injury Reporting:All injuries to football players in the

sample schools were reported through theNational Athletic Injury/Illness ReportingSystem (NAIRS), established by ThePennsylvania State University in 1974.NAIRS receives weekly reports, submit-ted by team trainers or physicians, of inju-ries and illnesses sustained by members ofan athletic team during practice and duringcompetition. In this study injuries and ill-nesses were classified by NAIRS into fourcategories, as follows:

1. Minor - any reportable injury/illness(other than dental or head injuries) thatdid not prevent an athlete from return-ing to practice or competition for longerthan seven days following the injury orillness.

2. Significant - all head and dental injuries( regardless of time lost from play orpractice), and any injury/illness thatkept an a thelete from returning to playor practice for longer than seven days.

3. Major - any significant injury/illnessthat prevented a player's return to prac-tice or competition for 21 days orlonger.

4. Severe - any permanently disabling in-jury, such as paraplegia.Injuries/illnesses were reported on

standard forms to NAIRS and coded intothe system's data bank. Trainers of thecooperating schools included in their re-ports the location of the activity at the timeof injury (playing field, practice field, orelsewhere) and their options about thelikelihood of a casual relationship of play-ing surface to injury (definitely related,perhaps/possibly related, or definitely notrelated).

At the end of the season, data collectedduring the football season of the 12schools - nature and category of injuries,condition of the field (wet, frozen, etc.)when the injury occurred, and the opinion

of the trainer as to the relationship of theplaying surface condition to occurrence orseverity of the injury were compiled forstudy and analysis by the authors of thisstudy.

Injury reports from two of the schoolswere not compete, and these schools werenot included in the comparisons of injuriesto conditions of playing surfaces.

Field Assessment:School representatives provided infor-

mation about maintenance practices anduses over the previous year. Maintenancepractices included fertilization, liming,aeration (core cultivation), mowing, irri-gation, overseeding, and control of weeds,insects and diseases. Uses included foot-ball games and practices, other varsity andintramural sports, physical educationclasses, band practices, community ac-tivities, and other activities. Estimatednumbers of occurrences for each use wereobtained.

Game and practice fields were evaluatedtwice - first in August, prior to or duringpreseason football practice, and again inearly November as the season was ending.Inspections and evaluations were made bytwo turfgrass specialists from the Collegeof Agriculture. Data were collected onkinds and amount of turfgrass, kinds andamount of weeds, total vegetative cover,turfgrass density, total weed coverage,smoothness of the surface, vegetativeclumps, and stones on the surface. Therecorded ratings represented a consensus.Data for subjective evaluations were as-signed code numbers for use in statisticalanalysis. Evaluators inspected game fieldsat nine areas (between inbound hash marksand near each sideline at midfield and neareach goal line). Areas inspected on thepractice fields were selected to representobvious differences in the playing sur-faces. As part of the final field inspection,each field was also characterized accord-ing to undulations (free draining swales),depressions (which could hold water),crown or slope, and internal drainage. Incontrast to ratings for natural undulationsor depressions, the field roughness ratingwas an indication of holes and other ir-regularities caused by play. Also duringthe initial visit, soil samples were taken fordetermination of soil textural class, bulkdensity, pH, and available phosphorus (P)and potassium (K). Samples for bulk den-sity represented the more intensively usedportions of the fields. The percentages of

sand, silt, and clay and the textural class ofthe surface soil were obtained by particlesize analysis using a hydrometer method.Bulk density, the mass of soil per unit bulkvolume, was determined from 10 soilcores, each an inch in diameter and 2.5inches long. Samples from the surface 2.5inches were used for pH determinationusing a 1:1 soil-to-water paste, and forphosphorus (P) and potassium (K) usingBray No. 1 and neutral, normal ammoniumacetate extractants, respectively.

Upon completion of the second evalu-ation, Penn State specialists prepared aletter that described field conditions andsuggested maintenance and/or renovationprograms for fields at each school.

"As many as 20% offield injuries could

have beenprevented... by

more favourablefield maintenance."

Characterization of Data:The number of injuries occurring during

games (expressed as injuries per 1000 ex-posures) was compiled for the total sampleof 10 schools and for each individualschool. Data were summarized to indicatethe number of reported injuries on eachfield, the relation of injuries to field con-ditions, and the number of injuries withinvarious body-part categories.

Statistical procedures involving Spear-man rank-order correlations for non-para-metric data were determined to ascertainthe possible relationships among the inci-dences of injury, field characteristics, andmaintenance practices. The variables usedin correlations were as follows:Soil Properties: Sand (%), Silt (%), Clay

(%), Bulk Density (g/cc), pH, AvailableP (lb/A) and Available K (lb/A).

Field Surface Rating Codes For Undula-tions, Depressions and Roughness: 0 =none, 1 = few, 2 = moderate, 3 = many,4 = extreme.

Field Rating Codes for Stones ( 1 cmdiam.): 0 = none, 1 = few, 2 = many.

Field Rating Codes for VegetativeClumps: 0 = none, 1 = few, 2 = many.

Vegetative Characteristics Rating Codes:Aug. & Nov. Cover: 0 to 9 where 0 = none,

9 = 100%Aug. & Nov. Weeds: 0 = 2%, 1= 2 to 25%,

2 = 26 to 50%, 3 = 51 to 75%, 4 = 75 to100%.

Aug. & Nov. Density: 0 = bare, 1 = thin,2 = moderate, 3 = dense.

Maintenance Factors:Nitrogen fertilization (lb/1000 sq.ft./year)Aeration or core cultivation (no. ofpasses/year)Mowing height (inches)

Use Rating: 0 = light, 1 = moderate, 2 =heavy, 3 = severe

Overall Field Rating: 0 = poor, 1 = fair, 2= good, 3 = excellent.

Injuries - possibly or definitely field re-lated (number).

When field conditions varied across afield, ratings used for correlations wererepresentative of the area between the in-bound hash marks.

Discussion of Results

Reported InjuriesA total of 210 injuries were reported by

the 10 participating schools. Of these in-juries, 96 occurred in varsity or juniorvarsity games, 4 in practice games, and110 during scheduled practices. Of theseinjuries, 152 were classified as minor and58 were significant. Of the significant in-juries reported, 23 were major. No severeinjuries were reported. The 10 schools hada total of 35,155 exposures during thefootball season (31,816 and 3,339 in prac-tice and games, respectively). Rates ofinjuries per 1000 exposures were 4.21 forminor injuries, 1.59 for significant inju-ries, and 0.65 for major injuries.

Although the number of injuries sus-tained in practices was about the same asthat in games, the number of exposuresduring practices, based on the average sizeof squads ( practice or game), and thenumber of sessions (practice or game) wasnearly 10 times as great as the number ofgame exposures. However, the severity ofcontact and intensity of play during thegames probably were considerably greaterthan for the practice sessions.

Of the 210 injuries reported, 12 (5.7 per-

cent) were definitely field related, 15.2%were considered possibly field related, and76.7 percent were definitely not field re-lated. In the judgement of the trainers re-sponsible for recording the data onlocation at the time of injury, a total of 44injuries (20.9 percent) may have beencaused by poor field conditions. On thebasis of these data, it can be estimated thatas many as 20 percent of the reportedinjuries could have been prevented or per-haps rendered less severe by more favour-able field conditions. Safety conditionsshould thus be an incentive for the con-struction and maintenance of high-qualityplaying surface, for practice as well asgames.

Within each body-part category, injuriesare further classified according to theirrelation to field conditions. As would beexpected, most of the injuries judged to berelated to field conditions involved thelower extremities (i.e., hip/leg, knee, andankle/foot). Also, it should be noted thatthe majority of injuries to lower extremi-ties were classified as definitely not fieldrelated or, in other words, they were con-sidered by the athletic trainers in atten-dance at the time of occurrence to beinjuries likely to have been sustained re-gardless of field conditions.

Field CharacteristicsField Maintenance: Data collected on

maintenance of game and practice fieldsindicated considerable variation betweenfields at a particular school as well asamong fields of different schools. Al-though practice fields were much moreintensively used than were the gamefields, they received less care.

Mowing heights were similar on gameand practice fields, but game fields re-ceived more nitrogen fertilization andmore aeration than practice fields. Gamefields averaged 2.0 lb. NIlOOOsq. ft. com-pared to 0.2 lb. N/1000 sq. ft. for practiceareas.

Herbicides were used for weed controlon 25 percent of the game fields: not oneschool reported use of weed killers onpractice fields. All fields receiving weedcontrol chemicals were treated with a pre-emergence crabgrass herbicide and a com-bination herbicide for broadleaf weedcontrol.

Eighty-three percent of the 24 fields in-volved in this study were overseeded in thespring. Only 75 percent of the 12 playingfields and 25 percent of the 12 practice

Practice fields wereused more, yet

received less carethan game fields.

fields were aerated. Not one of the schoolshad access to a disk seeder, and only a fewschools had access to aerators. Some of thefields were thus overseeded without ade-quate seedbed preparation. Without theseed-to-soil contact provided by properpreparation of the seedbed, success of theseeding is highly unlikely.

Field Conditions: Game fields were inbetter condition than practice fields. Ingeneral, game fields had smoother sur-faces, lower bulk densities (less compactsoil), fewer weeds, more vegetative cover,and more dense turf. The better conditionson the game fields are no doubt a reflectionof better construction and maintenancepractices. Soils on all fields were mediumor fine textured and were distributedamong the following textural classes:loam, silt loam, clay loam, silty clay loam,and silty clay. Kentucky bluegrass was thepredominant turfgrass species on mostfields. Perennial ryegrass had been used tooverseed fields; in some instances, the rye-grass population approached or exceededthat of Kentucky bluegrass.

Weed cover decreased during the sea-son, primarily because of the poor wearingqualities of species such as clover andknotweed, and loss of summer annualssuch as crabgrass, goose grass, and knot-weed. Lower ratings for vegetative coverduring the second of the two evaluationswere associated with reductions in weedpopulations. Turf density likewise de-creased during the season: most practiceand some game fields were nearly or en-tirely without vegetative cover betweenthe inbound hatchmarks at the second ofthe two field evaluations.

Additional or more effective mainte-nance practices (i.e., aeration, fertiliza-tion, overseeding, and weed control) wereneeded on most of the game fields and on

all practice fields surveyed in this study.Practice fields were used more than gamefields, but received lower levels of main-tenance. All practice fields in this studywere considered to be in poor condition,thus presenting surfaces potentially moreconductive to player injury.

Relationship Between Various FieldVariables: Correlations were used to indi-cate a relationship between two variables.Two variables may be correlated becauseone directly affects the other, or becauseboth are influenced by an external factor.A negative correlation coefficient indi-cates that one variable decreased as theother increased.

Statistically significant correlationsbased on data from all fields were listed.In general, correlations indicated that thefield with better maintenance practicesalso had better field conditions. goodmaintenance practices seemed to be a car-ryover of good construction methods. Forinstance, factors associated with higherrates of nitrogen fertilization were fewerundulations and depressions, more aera-tion, lower bulk density, fewer weeds, andgreater cover. Factors associated with in-creased aeration were higher nitrogen fer-tilization, fewer weeds, and greater coverearly in the season. Fields with the mostdepressions also had more undulations, arougher surface, more stones, less denseturf, less cover, less nitrogen fertilization,and severer use.

Good cover prior to the season was asso-ciated with higher N fertilization, moreaeration, greater density, less roughness,fewer depressions and stones, and less use.At the conclusion of the season, bettercover was associated with good cover inAugust, greater density in August and No-vember, smoothness, fewer depressionsand undulations, lack of stones, less use,and fewer weeds in August.

The highest correlations with use ratingswere the negative correlations with den-sity in August and with cover in Augustand November. Cover in November gavethe best correlation with overall field rat-ing.

Correlations were also determined forgame fields only and practice fields only.Fewer significant correlations occurredwhen the sample was limited to eithergame or practice fields; however, the re-sults tended to support the relationshipfound when all fields were considered.The complexity of interpreting correla-

tions can be illustrated by the negativecorrelation between aeration and Novem-ber density for game fields. One mightquestion the result because it seems that abetter aerated field should better support aturfgrass stand. On the other hand, fieldsthat have a less dense cover are in greaterneed of aeration, and the data suggest thatthey are getting more.

Recommendations for Field Improve-ment: Good fields were associated withgood management programs. Some fields,however, were poor because of construc-tion methods and needed renovation be-yond that provide by normal maintenancepractices. Suggestions for maintenanceand renovation programs were sent to eachschool following the second field evalu-ation. Subsequent visits have indicatedthat those schools that followed these sug-gestions have substantially improved theirfields.

Methods for getting information aboutconstruction, maintenance, and renova-tion of fields to those in charge of fieldmanagement must be implemented andimproved. Valuable information is pub-lished in various forms, but it may not bereaching those having the greatest need.Chalmers (Tech. Turf Topics 7: 1982) re-

ported that a survey of football field man-agers in Virginia indicated that 78 percentwere not happy with the turf quality oftheir fields and 94 percent wanted to im-prove the quality of the fields. Countyextension personnel, extension special-ists, turf consultants, representatives ofturf equipment and supply companies, andothers involved in turfgrass managementcan and usually are quite pleased to pro-vide guidance and information about ath-letic field maintenance.

The quality of construction and mainte-nance use for school fields may be relatedto socioeconomic factors within the com-munity. Our results indicted a trend forbetter maintenance practices on betterconstructed fields. Such a trend may havebeen coincidental, but it should be an in-centive to construct and maintain highquality playing surfaces.

In general, better field conditions wereassociated with better maintenance.Schools with well- constructed fieldsoften had better turf management pro-grams. Practice fields were used more thangame fields, but received lower levels ofmaintenance and were in poorer condi-tion. Additional or more effective mainte-nance practices (i.e., aeration, fertiliza-

tion, overseeding, and weed control) wereneeded on all practice fields and mostgame fields evaluated in this study.

[Reprintedfrom The Turf Line News, Vol.120, No.2, pp. 28 - 33, 1994J

GRASS CLIPPINGS

In a monocot the leaf sheathis often a structural or sup-port element. Theoverlapping sheaths form atube through which the newleaf or stem grows. An ex-treme example is thebanana '~ree." A fifteen-foot'trunk' is formed by overlap- .Jping leaf sheaths. The stemremains below ground untilflowering, when a flexiblestem snakes up an outthrough the top to form flow-ers and fruit.[Madison - Principles of TurfCulture]

Eliminate spray driftwith

THE WINDFOlL

Harry Shapko - Central Ont.Bill Carnochan - West Ont.Dave Telfer - East Ont.Chuck Demers - North Ont.

OJeCQ INC. "The turlseed specialists"P.O. Box 219, Brampton, Ontario L6V 2L2

Phone 905-846-5080 Fax 905-846-6909Phone 800-668-5080

PICKSEED~The home of Sportsturf Magic

George BannermanIan M.Clark

PICK8EED CANADA INC.Box 304, Lindsay,

Ontario, Canada K9V 483Phone 1-800-661-4769

FAX (705) 878-92491-800-661-4769

Res: (416) 773-4862Car: (416) 399-9721

Telephone 416-247-7875. Fax 416-247-6540

Douglas (Doug) MacMillanSales Manager

Lawn & Turfgrass Products