4‘ W 'T THE EMT-Ll UI' ébhflklfiu URN-I AHIIVIIIEJ Vl‘ THE KNEE EXTENSION STRENGTH AND INJURY INCIDENCE OF HIGH SCHOOL FOOTBALL PLAYERS Thesis for flu Degree OI M. A. MICHIGAN STATE UNIVERSITY Johnny Mitchell Hinton 1957 4:» <99 '5? MICHIGAN E UNIVERSITY INSTRUCTIONAL ‘ TERIALS CEN COLLEGE or cxmou THE EFFECT OF SELECTED DAILY ACTIVITIES ON THE KNEE "EXTENSION STRENGTH AND INJURY INCIDENCE OF HIGH SCHOOL FOOTBALL PLAYERS by Johnny Mitchell Hinton AN ABSTRACT Submitted to the College of Education of Michigan State University of Agriculture and ApplkniScience in partial fulfillment of the requirements for the degree of MASTER OF ARTS Department of Health, Physical Education; and Recreation 1957 Approved BUREAU OF EDUCATIONAL RESEARCH CCLLESECF‘EDUQXHON AHCrJG~FISfAlE UNPJHENTY LAST mums. mama/m [I’ll 4““. 4' UV ABSTRACT JOHNNY MITCHELL HINTON Title. The Effect of Selected Daily Activities on the Knee Extension Strength and Injury Incidence of High School AFootball Players. Statement of the Problem. To determine the: effect cfi‘ selected daily activities on knee extension strength and knee injury incidence. Methodology. The static knee extension strength and body weight were measured on a sample of two hundred eleven high school football players fdmml twelve high schools within a twenty-five mile radius of Lansing, Michigan prior to the 1955 football season. During the football season a record was made of all knee injuries. Tflmzplayers were also given a ques- tionnaire on which they recorded daily activities, i.e., dis- tance walked per day, ownership of car, et cetera. The quan- titative strength results and injury data for the subjects' responses on the questionnaire were then statistically ana- lyzed using analysis of variance and the chi square techniques. Conclusion. Bk) statistically significant differences were found hiquestionnaire responsecnlknee extension strength or knee injury incidence. These results would tend to refute the prevailing concept of "automobile knees” being the cause of the high knee injury incidence. THE EFFECT OF SELECTED DAILY ACTIVITIES ON THE KNEE EXTENSION STRENGTH AND INJURY INCIDENCE OF HIGH SCHOOL FOOTBALL PLAYERS by Johnny Mitchell Hinton A.THESIS Submitted to the College of Education of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF ARTS Department of Health, Physical Education, and Recreation 1957 ACKNOWLEDGMENTS The writer is profoundly grateful to his advisor, Dr. Wayne D. Vaanuss, Associate chfessor of Health, Physical Education and Recreation, for the helpful suggestions and criticisms given during the preparation of the study. Expressions-of gratitude are also due Dr. Reva White Allman, Professor of Education, Alabama State College, for invaluable consultative service. Gratitude is extended to the players euui coaches who cooperated wholeheartedly. Special indebtedness is acknowledged to my wife, Vera L. Hinton, for the inspiration and kindness shown during the preparation of the study. ii TABLE OF CONTENTS CHAPTER PAGE I. INTRODUCTION OF THE PROBLEM . . . . . . . . . . . l The Problem . . . . . . . . . .'. . . . 2 Statement of the Problem . . . . . . . 2 The Need for This Study . . . . 2 Source of Data . . . . . . . . . . . 2 Definition of Terms Used 2 Knee Injuries . . . 2 Selected Daily Activities . 2 Static Knee Extension Strength 2 Procedure Used in Carrying Out This Study . 3 Limitations 3 II. A REVIEW OF RELATED LITERATURE . . . .‘. . . u Prevention of Knee Injuries . . . . . u Exercises and Procedures for Strengthening and Rehabilitating Players . . 9 III. METHODOLOGY . . . . . . . . . . . . . .1. . . . . In Development of the Questionnaire . . . . . . . lu Contacting Respondents . . . . . . . . . . . . 1H Distribution of Questionnaire . . . . . . . . . 15 Tabulation of Data . . . . . . . . . . . . . . 15 Statistical Analysis . . . . . . . . . . . . . 15 IV. ANALYSIS AND PRESENTATION OF THE DATA.. . . . . . 17 Introduction . . . . . . . . . . . . . . . . . 17 Analysis Of Data . . . . . . . . . . . . . . . 18 Presentation of Data . . . . . . . . . . . . . 18 Discussion . . . . . . . . . . . . . . . . . . 30 V. SUMMARY, CONCLUSION, AND RECOMMENDATIONS. . . . . 31 Summary . . . . . . . . . . . . . . . . . . . . 31 ' COHCIUSIOH 0 o o o o o o a o o o o o o o o o 0 32 Recommendations . . . . . . . . . . . . . . . . 32 BIBLIOGRAPHY . . . . . . . . . . .V. . . . . . . . . . 3h APPENDIX, Questionnaire . . . . . . . . . . . . . . . . 37 iii TABLE I. II. III. IV. VI. VII. VIII. IX. XII. XIII. XIV. XVII. XVIII. XIX. LIST OF TABLES Place Of Residence Distance of Residence from School Means of Transportation to School . . . . Distance Walked Per Day . . . . . . . . . Frequency of Bicycle Riding . . Personal Ownership of Car . . . . Frequency of Using Parents' Car After School Job . . . ... . Hours Devoted Per Week to After School Job Type Of.Aft€F School Job . . . . . . . . . Special Jobs Assigned Around Home . . . . Summer Job . . . . . . . . . . Hours Devoted Per Week to Summer Job . . . Type of Summer Job . . . . . . . . . . . The Distance Which Can be Swum . . . Frequency of Swimming During Summer . . Farm Work in Summer . . Participation in Other Sports Wearing of Knee Braces or Wraps iv PAGE 19 19 20 2o 21 21 22 22 23 23 21L 21+ 25 25 26 27 27 28 29 CHAPTER I INTRODUCTION OF THE PROBLEM Footballis probably the outstanding sportzhlthe United States. at both the college and high school levels. Forsythe states that 799 high schools of Michigan play football at the varsity or intramural levels.1 Since the frequency (fl? participation is high in this particular sport, fl;is of major concern that it also produces the greatest number of knee injuries. There were seventy knee injuries for which athletic insurance claims were paid among Michigan high school football players during the season Of 1956. lflyurteen Of these injuries required surgery.2 . Icgan.believes that knee injuries present the most dif- ficult problem in athletic training.3 The prevalence of knee injuries in football, basketball, baseball, and hockey, indi- cates the seriousness of the problem and places unusual re- sponsibilities on the coach. . 1Charles E. Forsythe, "Athletic Accidents,” Michigan High School Athletic.Association Bulletin, XXXIII (August, ’18 - 21bid., p. 25. 3Gene A" Logan and Ronald E. Logan, Techniques of Ath- letic Training_(Los Angeles: Franklin-Adam Press, 1952), p. u. 1 2 If‘some means of preventing or minimizing knee injuries could be found, it might be helpful Us both the participants and the coaches. li.was primarily for this reason the present research project was carried out. The Problem Statement of the Problem. To determine the effect of selected daily activities on static knee extension strength and knee injury incidence. The Need for This Study. Methods are needed to prevent the high incidence of knee injurges and to understand factors contributing to this high incidence. Source of Data. Two hundred and eleven varsity foot- ball players from twelve Michigan high school located within a radius of twenty-five miles of Lansing, Michigan, served as subjects for this investigation. Definition of Terms Used Knee Injuries. Any knee injury which kept players out of action for two weeks or more. Selected Daily Activities. The activities about which information is sought on the questionnaire. Static Knee Extension-Strength. The ability Of the ex- A tensor muscles of the leg to apply tension at 110° Of extension. uH. H. Clarke, Cable Tension Strength Tests (Chicopee, .Massachusetts: Brown MurphyTCo., 1953), pp. 12-15. Procedure Used in Carrying Out This Study Prior to the 1955 football season, two hundred eleven subjects' statk:knee extension strength and weight were meas- ured. Following these measurements, it was considered infor— mation regarding the players' daily activities would be of interest. From the review of related literature and contact with coaches, doctors, and trainers, a questionnaire was then prepared. .A copy of the questionnaire is included in Appendix A. The questionnaires were taken to the respondents at each school at the completion of football season. After col- lecting the questionnaires, an analysis of the data was begun. The data obtained were organized, tabulated, and statistically analyzed. .Limitations. The limitations of this study are as follows: 1. The results are limited to static strength only. 2. Restriction Of the sample to one geographical loca- tion. CHAPTER II A.REVIEW OF RELATED LITERATURE The literature reported has been organized into the 'foilowing sections: 1. Prevention Of knee injuries. 2. Exercise and procedures for strengthening anui re- habilitating players. In searching the literature, no quantitative evidence was found relating activitiescn*strength of football players to knee injuries. Some Opinionated material is available,but very little quantitative evidence can be found. Aszniexample Warner states that strong knees are less susceptible to knee injury. lfizfurther indicates the boys should engagein.activ- ities of walking a distance of two miles or more every day during the first week of practice and,if the boys seem to be progressing well, the distance may be increased.1 Prevention Of Knee Injuries Ochsenhirt thinks that it is important to give proper attention to the young athlete. VHuHI he calls attention to the susceptibility Of adolescents to injuries, Ochsenhirt states: 1Lt. Jack Warner, "Sport Injuries Prevention," Scho- _£astic Coach, September, l95h, p. 39. 5 The adolescent years are fruitful, yet dangerous for the athlete. The structure of his body is developing, but has not reached physical maturity. For example, long bones are more susceptible to fractures, epiphyseal sepa- rations, dislocations, etc. The judgment Of a qualified roentgenologist is necessary too in X-ray evaluations. Frequently, young tissues although fresh, virikzand flex- ible, have neither natured, nbr have they'been trained sufficiently to develop tensile sérength so necessary for the stresses they must withstand. GallagheE3states that if adolescents are to avoid knee, ankle, and low back strains to which strenuous activities sub- ject them, they would do well to supplement their games with exercises which are specifically designed to increase the size and power of those muscles which support joints and help to protect the joints from injury. Bilik states that pre-season conditioningis.fundamental in the prevention of subsequent mishaps.u Ikzobserves that men who will not take time to get "in condition" will be "out of condition," will grow stale, or may be easily injured. Gallagher further points out that conditioning exer- cises, attention to the proper fitting Of shoes, and the proper use Of adhesive strapping are a few of the important matters 2N. C. Ochsenhirt, "Prevention and Management of Ath- letic Disabilities," Archive of Physical Medicine, XXXIV IMarch,1953),158. 3Roswell Gallagher, Adolescents' Progressive Resistance Exercise, in Thomas L. Delorme & Arthur L. Watkins ed. (New Tork: Appleton-Century Crofts, Inc., 1951),. 206. “s. E. Bilik, "Athletic Training and the Treatment of .Athletic Injuries," Illinois Medical Publication, 31, (Decem- ber, 1930), 79, Arcthes Physical Medicine and Rehabilitation, 34 (March, 1953), 158. BUREAaJ OF EDUCATIONAL RESEARCH COLLBmiCT7EDUCAfiON MICHIGAN STATE UNIVERSITY EAST LANSING. MICHIGAN 6 to consider in the attempt to control the knee injuries con— nected with such a game as football.5 Thorndike states that special exercises divised by Ray- croft and Crisler at Princeton for increasing the strength of the knee and ankle joints are distinctly beneficial and good prophylaxis for any squad in early season training.6 McCloy believes that sport injuries to joints, such as the knee are caused by strains which are placed on the liga- ments of the joints, and are, consequently, too much to be borne by the ligaments, and hence give way with a rupture of the ligament, either partial or complete:7 In the case of the knee, these injuries may be to the medial or lateral collat- eral ligaments, to the posterior cruciate ligament, or tears of the meniaci between the femur and tibia. McCloy lists two types of procedures that can help to prevent such injuries. The first procedure is to greatly strengthen the muscles passing the joints. For example, in the knee one needs to strengthen the quadriceps and the ham- strings.8 5Gallagher, op. cit., p. 222. 6Augustus Thorndike, Athletic Injuries (Philadelphia: Lea and Febiger, 1956), p. 58. 7H. C. McCloy, "Knee Injuries," Exercise Program to Strengthen Ligaments of Knees and Ankles_(IowaTCityr State University of Iowa Press, January, 1957), pp. 1-2. 81bid., p. 1 The second type of procedure is to strengthen the liga- ments directly. McCloy further states: To strengthen (and hypertrophy) ligaments progres- sive strains should be put on them. Chm illustration is found in the operation used by orthopedists; this purpose is to compensate partially for the disability Of children in whom there is total paralysis of the abdominal muscles due to poliomyelitis but in whom the thigh flexor muscles are intact. Here, a strip of fascia latae is often re- moved from each thigh and implanted under the skin of the abdomen, attached from the lower ribslithe pubis. After several'months, these strips of fasciae latae hypertrophy and unite after treatment and are fifty per cent wider and several hundred per cent thicker than they were when im- planted. This same thing can happen to ligaments of knee and ankle when progressively greateroand greater stresses are systematically applied. McCloy states further: In addition to the support given to the knee joint,Iy'the strengthening of the muscles passing the knee joint, an- other'phenomenon is noted. . . . The vastus medalis and the vastus lateralis insert not only on the patella with the rest of the quadriceps, they insert also in retinacu- lum patella, associated with the capsular ligament of the knee, and blending posteriorly into the collateral liga- ments; hence, when the quadriceps muscles are greatly strengtBened these ligamentscfi‘the knee are also strength- ening. Regarding the techniques for strengthening the ligament of the knee and ankle, McCloy states: One cd‘the best techniques is to use "iron boots" with attached weights. Here the subject first sits on a bench INLUT a pad under the knee of the foot to which the iron boot. is attached. The weight should at first be about one-half of what the subject can lift ten times by extending the lower leg fully. Ikzshould lift this weight ten times, then increase the weight as many times as pos- sible. After a further rest of about two minutes, he should again lift this weight a maximum number of times. When the subject can lift it from twelveixnfourteen times, 91bid.fl, p. 1 101mm, p. 3. 8 the weight should be increased until he can lift it only eight to ten times. The second technique is to pair the subjects Off,and have each offer resistance to the other of the pair.11 ' McCloy has found: Exercises such as these not only result in the strength- ening Of the ligaments Of the knee, but also add from 50 to 90per cent tOOthe strength Of the musclefeof the leg-- a factor not entirely useless to football. Delorme and Watkins as reported by Klein state that runnerous authors concur in the values of specific exercises for injury prevention, but few have outlined specific proced- ures for accomplishing the desired goals for massive muscular strength, and power for reducing the effect of medial and lat- eral hinging which is highly responsible for the medial and lateral ligament and cartilage problems.13 There is also an apparent lack of emphasis on related literature on the impor- tance of muscular flexibility relative to its value as an im- portant phase of the conditioning efforts. Klein further points out: In order for the exercise technique to have the relative value as applied in progressive resistive exer- cise, some of the following points should be considered: 1. The muscle groups have to be placed under pro— gressive stress. 2. The exercise should have some semblance Of in- dividual prescription. ”1mm, p. 2. 121mm, p. 3. 13Karl K. Klein, "A.Preliminary Study of the Dynamics of Force As Applied to Knee Injury in Athletics as Related to the Supporting Strength of the Involved Musculature," National Athletic Trainers' Journal (December, 1956), passim. 9 3. The exercise should be resistive enough to work in the strength power areas of development as well as to consider endurance qualities. 4. The exercise should be able to develop desired qualities of strength and power at a rapid rate so the protective qualities may be developed early in or previous to, the competitive season.1& Colthard sums up the problem by emphasizing strong mus- culature for injury prevention in that the‘fifllfllis more firmly bound together and lateral movement is reduced.15 He states further that good muscle tone will tend to lessen injury when a player who is relaxed is hit on the field.16 Exercises and Procedures for Strengthening and Rehabilitating Players Gallagher states that the tendency of knee injuries to recur if well known and hence the need for combating the atrophy and hypotonia of the extensor muscles of the thigh which accom- pany these injuries is most important.17 Gallagher further ob- served that whether or not the ligaments are torn, whether or not the cartilage is damaged or removed," the most important 1L'"Ibid., pp. 3—u 15A“ L. Coulthard, "Football Conditioning,".Athletic Journal, XXXIII, No. 9 (May, 1953), u. 1611nm, p. L1. 8 17Thomas L. DeLorme and J. Roswell Gallagher, "The Use and Techniques of Progressive-Resistance Exercise in Adoles- cence," Journal of Bone and Joint Surgery, A: 8&7, l9u9, p. 31. 10 part Of the after-care Of knee injuries is the development of strength in the quadriceps.18 Recommended exercises, such as quadriceps setting, straight-leg raising, and walking are val- uable in the early after-care Of knee injuries and will gradu- ally improve the power Of the quadriceps; however, to prevent a recurrence Of injuries,it.seems logical to us to strive for more thanzareturn to former strength. ITIregard to the impor- tance of exercises in the restoring Of strength to muscles, Gallagher further states that: Progressive-resistance exercises can restore the power lost and can produce a much greater: strength. in the sup— porting nmscles than they possessed prior to the initial injury. Watkins20 points out that exercises which are regular, systematic, and have natural rhythm will tend to thicken and toughen the sarcolemma of muscle fibers. These exercises will also increase the amountcfi‘connective tissues within the mus- cle. It is observed, however, that there is an increase in Inuscle size,Infl;not an increase.h1the number of muscle fibers. The merits of stretching muscles intastrengthening program is expressed by Delorme when he states that: The loads to be overcome when performing progres- sive resistance exercise may stretch the muscles concerned beyond their normal resting length. This is advantageous. 18DeLorme and Watkins, op. cit., p. 208. 191b1d., p. 208. 20K. G. Watkins, "The Physiological Aspect Of Thera- peutic Physical Exercise," Journal of American Medical Asso- ciation, 1&2 (January lu, 1950), ION-106. II It has long been recognized that skeletal muscles develop greater force after they are previously stretched. Their elasticity appears to be sufficiently hight£>P€SISt tear- ing by loads and are capable Of being lifted under the con- ditions specified in the technic of application. Trauma of this type is ‘never observed in properly administered progressive resistance exercise. West Observes that experiences with 3k knee instability patients supports Watson Jones in his claim that following severe iigamentor injury, the patient may even return to strenuous athletics if the quadriceps muscle power has been completely restored.22 'West expresses further that protection of an unstable knee by a brace is indicated only after surgery and maximum redevelopment Of the quadriceps femoris muscle has failed to yield a serviceable knee.23 Thorndike has found that until the quadriceps return to their usual strength, the affected knee is not stable.2u West reports that no mechanical device could possibly stabilize the knee as effectively as powerful quadricep mus- 25 cles. .1. nghomas L. DeLorme and.Arthur L. Watkins, Progressive Resistance Exercise (New York: Appleton-Century Crofts, Inc., 1951), p. 10. 22Francis E. West, reported by Thomas L. DeLorme and Arthur L. Watkins, "The Knee," Progressive Resistance Exercise (New York:.Appleton-Century Crofts, Inc., 1951), p. 12;. 231mm, p. 125. 21+Augustus Thorndike, "Injuries to the Knee," Athletic Injuries (Philadelphia: Lea and Febiger Company, 1956), p. 206. 25West, op. cit., p. 125. l2 DeLorme observes that no joint ever completely recovers 26 The least one can do is to attempt to fhmmlasevere injury. protect itby'developing the supporting muscles to their maxi- mum. With regard to the effect of progressive resistance ex- ercise technique, DeLorme reports that: In observing 47 boys at Phillips Academy who were taking progressive resistance exercise in an attemptiinncrease the power of their quadriceps onbr3 of the E7 boys had a recurrence of knee injury, despite the fact that most of them were very active individuals in athletics. DeLorme further observed that one can be sure that the proba- .bility of a second injury is Inaterially' reduced when a high degree of quadriceps strength is achieved.28 lflein states that the use of progressive resistance ex- ercise as a post injury technique is a scientific nmthod of 29 approach in establishing maximum muscular function. Klein further thinks that the problem of rabuilding the muscles to their normal strength after injury does not particularly need specific technique of application, but once this normal level is reached systematic progressive resistance exercise is need- ed to build toward maximum muscular strength. It is further believed by Klein.that due to the known characteristics of muscles, atrOphy of the quadriceps and the hamstring muscles 26DeLorme and Watkins, op. cit., p. 209. 28 27221;!» p. 21? Ibid., p. 217. 29K. K. Klein, "A.Preliminary Study of the Dynamics of Force as Applied to Knee Injury in Athletics as Related to the Supporting Strength of the Involved Musculature," Athletic Journal, 1, No. 1 (December, 1956), 3. 13 groups, the application of progressive resistive exercise from the early restoration phase to completion of the pro- gram will produce maximum strength.30 These results may be anticipated within a period of four to eight weeks of exer— cise on a basis of three exercise periods per week. 30 H bid., p. 3. CHAPTER III METHODOLOGY Development Of the Questionnaire Following the literature review on knee injuries, in- dividual conferences were held with coaches, doctors, and trainers, and a number Of possible causes of knee injuries were listed. ’Nue questionnaire was then prepared to obtain information regarding these possibilities (Appendix.A). Contacting Respondents TTw list Of schools contacted was a part Of the sample 'used by Schrecengost}' TTds list made it possible to compose the qualitative questionnaire datato the more precise quanti- tative strength data. The subjects' static knee extension strength was measured pmeseason as described by Clarke2 and modified by Richards. The weight was also measured. The purpose of the study was explained in detail to the school 1Randall P. Schrecengost, "The Relationship Between Knee Extension Strength and Knee Injury Incidence Among High School Football Players" (unpublished Master's thesis, Mich- igan State University, East Lansing, 1957). 2H. H. Clarke, Cable Tension Strength Tests (Chicopee, Massachusetts: Brown Murphy Co., I953), ppffiI2-13. 1h 15 authorities enui permission granted in each case to make the investigation. Distribution of Questionnaire The questionnaires were taken to the schools partici- pating in the investigation. They were explained in detail to the subjects prior to filling them out. The questions were explained as to meaning. Aid was given when needed in completing the questionnaire. Two hundred and eleven players were contacted and their completed questionnaires provided the qualitative data for this study. Tabulation Of Data The questionnaires were numbered and the data tabu- lated on I.B.M. sheets and checked for accuracy. The data were then punched into I.B.M. cards and verified. Statistical Analysis The data were then sorted according to question. For each of the responses the necessary data were recorded or-cal- u culated for analysis of variance 5 of the quantitative data or chi square analysis of the qualitative data. For the latter, uG.‘W. Snedecor, Statistical Methods (Ames, Iowa: The Iowa State College Press, 1956), pp. 2MB, 2H2. 5Quinn, McNemar, Psychological Statistics (New York: John Wiley and Sons, Inc., l9fl9), pp. 207-210. 16 the total injuries and knee injuries were merely counted. For the analysis of variance, the sum Of the X's and sum of the X squares were calculated. The remaining portions of the analysis were completed using a hand calculator. CHAPTER 1v ANALYSIS AND PRESENTATION OF THE DATA , Introduction This stu¢y was undertaken to determine the effect of selected daily activities on knee extension strengthznuiknee injury incidence of high. school football players. Raw static strength, strength per pound of body weight, total injuries, and knee injuries were considered. A comparison was made between the four items listed above and (I) place Of residence, (2N distance of residence from school, (3) means of transportation to school, (A) dis- tance walked per day, (éfl frequency Of bicycle riding, (7) personal ownership of car, (8) frequency using parents' car, (9) after school job, (10) hours devotedtn after school job, (12) types of after school jobs, (L3) special ‘yfla assigned around home, (HI) summer job, (H3) hours devoted to summer job per week, (léfl types of summer jobs, (L7) the distance which can be swum, (18) frequency of swimming during summer, (19) farm work, (20) participating in other sports, and (35) wearing of knee brace or wraps. 1? 18 Analysis Of the Data Prior to the football season static knee extension strengthland weight measures were made on two hundred eleven football players from twelve high schools within a 25 mile radius of Lansing, Michigan. Following the football season, the same subjects were given the questionnaire being investi- gated in this study. The data were sorted according to questionnaire re- sponses, and the quantitative raw static strength and strength per pound of body weight data were statistically analyzed by 2 The quantitative total the analysis of variance technique. injury and knee injury data were statistically analyzed using the chi square techniques.3 Presentation Of Data The data are presented in Tables ltO 19 arranged accord- ing to questionnaire responses. Where statistical significance exists, the "F" value or chi square value is asterisked. The probability level desired for significance was the five per cent level. In other respects, the tables are self-explanatory in nature. There were no responses to questions 5 and 11. 1H. H. Clarke, Cable Tension Strength Tests (Chicopee, Massachusetts: Brown Murphy Co., 1953), pp. 12-15. 2G. W. Snedecor, Statistical Methods (Ames, Iowa: The Iowa State College Press, 19567, pp. 2h0, 2H2. 3Quinn McNemar, Psychological Statistics (New York: John Wiley and Sons, Inc., 19E9), pp. 207-210. 19 TABLE I PLACE OF RESIDENCE Small City Town Country Farm "F" Value Strength Data Within vari- Raw Strength (M) 208 198 208 206 ance greater than between Within vari- St/Lb Body Wt. (M) 1.33 1.28 1.3u 1.3A ance greater than between Injury Data Chi Square Values Total Injuries 16 10 10 15 2.10 Knee Injuries 9 9 u 9 .33 N=69 N256 N=30 N=56 TABLE II DISTANCE OF RESIDENCE FROM SCHOOL l/u- 1/2- 3/u- Over O-l/u 1/2 3/u 1 1 "F" Mile Mile Mile Mile Mile Value Strength Data Raw Strength (M) 196 202 216 192 210 1.28 St/Lb Body Wt. (M) 1.27 1.32 1.36 1.26 1.35 1.10 Injury Data Chi Square Values Total Injuries 5 7 5 6 28 3.73 Knee Injuries u 5 3 u 15 1.55 N: N=2u =22 N=23 N=100 ' 20 TABLE III MEANS OF TRANSPORTATION TO SCHOOL Walk Bike Bus Car "F" Value Strength Data Raw Strength (M) 196 210 202 215 2.30 St/Lb Body Wt. (M) 1.28 1.uo 1.29 1.38 2.0a Injury Data Chi Square Values Total Injuries 18 0 13 20 2.26 Knee Injuries 11 0 6 In 1.12 N=9O N=1 N=38 N=82 TABLE IV DISTANCE WALKED PER DAY Over 1 2 3 5 Mile Miles Miles Miles Miles "F" Value Strength Data Within vari- Raw Strength (M) 20k 208 201 202 I92 ance greater than between Within vari- St/Lb Body Wt. (M) 1.31 1.3a 1.31 1.35 1.2A ance greater than between Chi Square Injury Data Values Total Injuries 10 19 6 6 5 1.98 Knee Injuries 5 1H 3 5 3 H.23 N=59 N=71 N=3o N=2l N=l7 21 TABLE VI FREQUENCY OF BICYCLE RIDING - Less 3-u 1-2 Than When Times Times Once Car Every Per Per Per unavail- Day Week Week Week able "F” Value Strength Data Raw Strength.UW) 21k. 168 189 200 217 l.u7 Within vari- St/LbBodth. (M)1.3o 1.15 1.29 1.31 1.38 ance greater than between Injury Data Chi Square Values Total Injuries 0 0 3 l2 7 .52 Knee Injuries 0 0 l 7 5 1.1a N=8 N=LI,‘ 11:15 N=113 11:25 TABLE VII PERSONAL OWNERSHIP OF CAR Yes No "F" value Strength Data Raw Strength (M) 215 199 5.14 St/lb. Body Wt. (M) 1.36 1.26 , 3.98 Injury Data Chi Square . Values Total Injuries 15 35 1.63 Knee Injuries 9 22 1.22 N=81 N=128 22 TABLE‘VIII FREQUENCY OF USING PARENT'S CAR Sev- eral Spe- Times cial Week Per Occa- .Any Ends Week sions Time Never "F" value Strength Data Raw Strength (M) 200 200 .207 215 192 1.50 St/LbBOdth.(M) 1.27 1.30 1.36 1.37 1.211 1.63 , Chi Injury Data Square Values Total Injuries 10 7 10 15 8 .67 Knee Injuries 5 6 6 9 5 .10 N=3u N=35 N=36 N=59 N=32 TABLE 1X AFTER SCHOOL JOB Yes NO "F" Value Strength Data Raw Strength (M) 202 207 Within variance greater than between St/Lb Body Wt. (M) 1.31 1.34 Within variance greater than between Injury Data Chi Square Values Total Injuries 24 26 .10 Knee Injuries 17 1h .25 N=10u N=103 23 TABLE X HOURS DEVOTED PER.WEEK TO AFTER SCHOOL JOB More 10- Than 1-3 u-6 7-10 15 15 "F" Value Strength Data Raw Strength (M) 181 201 215 19A 123 3.95 . , . . . Within vari- St/Lb BodyNHL.(M) 1.27 1.3A 1.35 1.30 1.26 ance greater than between Injurijatg Chi Square Values Total Injuries 0 6 5 6 14 1.67 Knee Injuries 0 3 1 5 10 3.28 N=11 N=15 N=26 N=25 N=u8 TABLE XII TYPE OF AFTER SCHOOL JOB Heavy Running Mild Lifting Errands ‘ Work "F" Value Strength Data Raw Strength (M) 206 187 196 1.2M St/Lb Body Wt. (M) 1.33 1.20 1.28 1.1a Injury Data Chi Square Values Total Injuries 18 1 13 1.97 Knee Injuries 13 1 6 3.u3 N=62 N=9 N=68 2h TABLE XIII SPECIAL JOBS ASSIGNED AROUND HOME Yes No "F" Value Strength Data Raw Strength (M) 20k 206 Within variance greater than between St/Lb Body Wt. (M) 1.31 1.33 Within variance greater than between Injury Data Chi Square Values Total Injuries 36 In .05 Knee Injuries 22 8 .10 N=lk7 N=61 TABLE XIV SUMMER JOB Yes No "F" Value Strength Data Raw Strength (M) 20A 288 Within variance greater than between St/Lb Body wt. (M) 1.32 1.38 1.09 Injury Data Chi Square Values Total Injuries H2 9 1.8h Knee Injuries 25 6 1.81 N=185 N=2u 25 TABLE XV HOURS DEVOTED PER WEEK TO SUMMER JOBS Over "F" 0-5 6-10 11-20 21-30 31-H0 HO Value Strengtthata Raw Strength (M) 190 210 177 198 205 212 1.57 St/LbBodth. (M) 1.35 1.33 1.19 1.27 1.33 1.35 1.13 Chi Injury Data Square I 'Value Total Injuries 0 0 0 3 10 31 H.28 Knee Injuries 0 0 0 2 6 18 2.13 =4 N=7 N=15 N=19 N=55 N=9l TABLE XVI TYPE OF SUMMER JOB Light Medium Heavy "F" Value Strength Data Raw Strength (M) 198 202 206 Within variance greater than between St/Lb Bodth..(M) 1.25. 1.33 . 1.33 Within variance greater than between Injury Data Chi Square Values Total Injuries 3 6 35 5.85 Knee Injuries 2 k 20 1.62 N=22 =u5 N=126 m 26 sanz omauz mmuz manz smuz oauz Am.a m as m a n o moaaerH ooex oo.m : mm m a m a moaaoeea Aesop moaam> ocmsvm «co Mpmo hcanca c663pon cmcp aoadoam ooeeaaes canoe: mm.a mm.a mm.a om.a mm.a Am.a sz .os.soom .os\aw Co63pon swap aooooao ooeoaae> canoas mom pom was com pom pom sz cameoaom 3am noon Emmanuem osfim> em: Efi3w mvcm> mecm> mucm> .mucm> mean» o.enO ooa ooa-m~ mNIOm omImm mm cm>O 233w mm ZX mqm¢H 27 TABLE XVIII FREQUENCY OF SWIMMING DURING SUMMER Every 5-6 3-u 1—2 0 "F" Day Days Days Days Days Value Strength Data Raw Strength (M) 200 182 210 207 222 1.66 St/Lb Body Wt. 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