Jounal of Athletic Training 1998:33(2):122-129@ by the National Athletic Trainen' Association, Inc

Injuries in the Sport of RacewalkingPeter R. Francis, PhD; Niles M. Richman, MA; Patricia Patterson, PhD

Department of Exercise and Nutritional Sciences, San Diego State University, San Diego, CA 92182

OSecfiw: To examine the nature and incidenca of injudessuffercd by racewalkers.

D*lgn and #ting: A total of 682 questionnaires weredistributed to racewalkers in the San DiegoAong Beach, CAarea, participants in a national qualiiling race held in Washing-ton, DC, and subscribers to lhe Ohb Racewalker.

Subjects: Four hundred questionnaires were retumed to theinvestigators, for a retum rate of ffi.7%.

Measurcnents: Questions addressed demographics, exer-cise pattems, competitive history, walking surfaces, types offootwear normally used for training and competition, and inju-ries suffered during racewalking. Questionnaire results weretabulated and chi-sguare analyses were used to test for inter-relationships. A stepwise discriminant analysis was used todevelop a model fior the prsdiction of injury in racewalking.

Resultc: Racewalking participation peaks in the 30- to39-year-old age group, while the proportion of injurcd partici-

pants is gleatest in those under 30. Most iniudc involved thelower extremity, but the "averags" rac€walkar $ffer€d only oneserious injury anery 51.7 years. Those participants sfio train€dsix or seven times per week were most likely to be injured;those who trained three or fEwer times per week wge leastlikely to be injured. The percentage of injured participantsincreased progressively with weekly training mileage. A modelbased on the data from this investigation corectly predlctedmembership in either the injured or uninjured group in only64.1% of cases and is, therefore, of limited us€ to the re-searcher or clinician.

Condusions: Although the rate of injudes in racswalkers islow, more qpternatic research is necessary before sportsmedicine professionals can confidently recommend consis-tently effective iniury prwention proc€dures.

Key Wotds: walking surfac6, footwear, training, injury pre-diction

he popularity ofracewalking has increased steadily eversince the sport was first included in the Olympic Gamesin 1908. International competitors have been drawn

from countries all over the world, but the two Olympic events(20 km and 50 km) are currently dominated by athletes fromMexico, Italy, and countries that were formerly pafi of theSoviet Union. Racewalking has not yet attracted large numbersof participants in North America, but there appear to beindications that the sport is growing in popularity. Racewalk-ing events of 5 and l0 km are becoming increasingly popularfor casual athletes, and successes in these relatively shortevents have encouraged some newcomers to attempt progr€s-sively longer races.

A number of walking enthusiasts have attributed the risingpopularity of racewalking to a decline in the popularity ofjogging and a concomitant increase in the number of peoplewho are taking part in exercise walking programs. It ispresumedl-3 that this trend has been influenced by the wide-spread belief that racewalking is a sport providing opportuni-ties for competition, as well as valuable health and fitnessbenefits, without significant risk of injury.

A review of the literature revealed that little has beendocumented about injuries associated with racewalking.Palamarchuka questioned 31 racewalkers and concluded thatthe individuals in his small sample were prone to the samekinds of injuries as runners. The primary complaint wasblisters of the heels and toes. Hamstring injuries were the nextmost common, followed in decrcasing order of incidence bymedial knee pain, nonspecific hip pain, plantar Tasciitis, shin

splints, shess fractures, and groin stains. In view of theincreasing popularity of racewalking, we reasoned that a

survey of a larger group of participants would provide addi-tional objective data that would be useful to the athletictraining and coaching communities.

METHODS

A detailed questionnaire was designed, field tcsted, andmodified before being administered to subjects used in the

investigation. In addition to questions of a demographic nature,the instmment elicited responses about exercise patterns (in-cluding racewalking and any other physical activities), com-petitive history, and the walking surfaces and types of footwearnormally used for training and competition. Finally, questions

were asked about injuries suffered during participation inracewalking. A distinction was made between injuries thatrespondents believed to have been the direct result of partici-pation in racewalking and injuries that were assumed to havebeen associated with prior orttropaedic history.

In an effort to establish a means of communicating with a

broad representative sample of the racewalking population, aninformal survey was carried out before the present investiga-tion. The survey revealed ttrat there was considerable variabil-ity in the available estimates of the sizp of the population ofracewalkers in the United States, especially with respect to thenumber of casual athletes involved in the sport. For example,estimates of the size of the total racewalking populationprovided by various individuals associated with the United

12. Volume 33 o Number 2 o June 1998

States Olympic Committee and the Athletic Congress varied

from 2,000 to 6,000 participants. Preliminary inquiries also

indicated that the mssq/elking population is widely distributedthroughout the nation.

Therefore, trro different methods were used in an anempt to

obtain a representative sample from this sparse and widelydistributed population.

One of the investigators (N.M.R.) met personally withpotential subjects at competitions held at rwo widely separated

geographic locations. Seventy prestamped and preaddressed

questionnaires were distributed to competiton in the San

Dego/Long Beach area in California. An additional 100

questionnaircs were randomly disributed at a national quali-fying race held in Washington, DC. Finally, in an effort tocontact participants in other areas of the United States, amailing list was obtained from the editors og u t*sq/alkingnewsletter (The Ohio Racewall<cr), and questionnaires weredistributed to all 512 individual subscriben. Thus, the totalnumber of potential subjects was 682.

RESULTS

Data analysis was carried out when a total of 4(X) completedquestionnaires were received by the investigators, which represented a return of 58.7%. On the basis of available estimates,

the present investigation was based upon a sample of approx-imately 7% to 2OEo of the entire population of racewalkers inthe United States. All data were coded and analyzed so as toobtain descriptive and inferential statistics.

Demographic Information

The sample consisted of 294 males and 106 females whoseages ranged from 12 to 88 yea$ (mean = zl4 years). History ofparticipation in the sport for the individuals in the sample

ranged from 3 months to 62 years (mean : 8.04 years). Thesample included participants from all but five states. About one

third of the subjects (34.6%) indicated that they began

racewalking after being injured in another sport. Of these

subjects, 89% indicated that running was the activity respon-sible for the earlier injuries. The remaining subjects indicatedthat they had suffered injuries while taking part in a variety ofother activities, of which football, bicycling, and soccer werereported most frequently.

Exercise Habits

Most respondents (357 : 89.3%) indicated that they tookpart in competitive walking events ranging in distance from Imile to the marathon, but it was apparent that the level ofparticipation varied greatly. Figure I summarizes the average

frequency, duration, and weekly mileage of the racewalkingexercise of the subjects. The variability clearly indicates that

the sample included participans who ranged from casual

racewalkers to serious competitors.

10-30 31-60 61-90 91-120 121-200Mlnules of italnlng per sesslon

10 20 30 40 50 60 70 80 90 100

Weekly lralnlng mllaage

Ftg 1. FrcquencA and durston of tralning secslons and averageweekty mibage of 4O0 racewalkenr.

Most participants reported that they werc concurrentlyparticipating in other athletic activities, of which running,bicycling, swimming, and weight training were the mostcornmon. The great majority of participants (83%) indicatedthat they took part in some forrr of stretching program inconjunction with their racewalking programs. Almost twothirds of the subjects (213 : 63.2%) reported that theystretched both beforc and after exercise.

Footwear and Walking Surfaces

A little more than one third (150 : 37.5%) reported thatthey normally used shoes designed for racewalking duringtraining and competition. However, more than half of the

respondents (239 = 59.8%) wore shoes that were designed forrunning. The remainder reported that they normally wore a

variety oftypes offootwear, including shoes designed for courtand racquet sports.

Most respondents (61%) indicated that they exercised almostexclusively on a single type of ground surface. Almost half ofthese individui'ls (195 : 48.8Vo) performed on concrete for the

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Joumal of Athletic Training 123

majority of time, while 156 (397o) did most of their walking on

asphalt. Other individuals reported that they trained on a

combination of surfaces, including various indoor and outdoor

tracks (all-weather, cinder, dirt, wood, grass) and treadmills.

Injuries

Incidence of \iuries. About two thirds of all respondents

(257 = @.2%) reported that they had suffered one or moreinjuries during their racewalking careers. The incidence ofsuch injuries was remarkably similar for females (69 : 65.l%o')

and males (188 : 63.5%). The 400 respondents in the

investigation reported a total of 502 injuries, which, based onthe mean length ofparticipation of 8.04 years, represents 0.156injuries per year per p€rson. Put in other terms, the "average"racewalker suffers one injury for every 6.4 years of participa-tion. On the basis of this observation alone, it would appear

that the widely held belief that racewalking is a relatively safe

sport is justified.Types and Locations of Injuries. During the planning

stages of this investigation, we assumed that some racewalkerswould be able to provide specific medical diagnoses of injuriesthat they had suffered. Conversely, we assumed that otherinjured individuals would be unable to provide such informa-tion for a variety of reasons, including the inability to recallprecise medical terminology or the fact that they had notreceived any form of medical attention. Thercfore, subjectswho were able to do so were given the oppormnity to providethe precise medical terms used to describe each of the injuriesthey had suffered. In addition, all subjects were asked toidenti$ the anatomic location of injuries that they had suf-fered.

About half of all reported injuries (247 : 49.29o) wereidentified with specific diagnoses (Table l). In apparentagreement with the observations of Palamarchuk,a we foundthat many of these injuries are similar to those suffered bynurners. The most common injuries reported by runners appearto be patellofemoral pain syndrome, tibial stress syndrome,Achilles peritendinitis, plantar fasciitis, and patellar tendini-tis.5'6 However, the most commonly reported injury in ourinvestigation was hamstring strain. A number of subjectsindicated verbally that they frequently suffered from blisters ofthe heels and toes, but only six cases were reported in responseto the questionnaire. Many racewalkers appear to regard a

blister as an inconvenience rather than an injury.Table 2 lists the anatomic locations and frequency of

occurence of all the injuries counted in this investigation. Ithas been reported that the knee is the site most commonlyassociated with injury in runners.6-e However, the foot andknee were almost equally affected by injury among theracewalkers in our investigation. During informal discussions,several competitors stated that racewalkers rarely if ever sufferknee injuries. However, this conlention was not supported byour data. Even though hamstring strain was the most frequentlyreported specific injury, the knee, shin, hip, and back were

Table l. Specifrc Diagnoses of Iniurles Roported by Sttblocts

Injury Frequency

Hamstring strainShin splintsGeneral ligament sprainsOther musde strainsTendinitis, footSpinal injuriesTendinitis, kneelliotibial band syndromeSciaticaPlantar tasciitisChondromalacia patellaGroin pulUstrain

Anterior tibial tendinitbMhritis, kneeUgarnent strain, kneeStress fracture, tootBlisters, footMhritis, other locationsStress fractures, other locationsGeneral tendinitisSesamoiditisNonspecific painBursitisAnterior compartment syndromeMuscle spasmOther conditionsTotal

Tablc 2 Locationg of Iniurles Reported by {Xl Racewalkers

Frequency

Psrcentag€ of All Injuriesat This Location Whh NoPrior Orhopedic History

2419

17171610I8I876666666555q

542

31

247

Location

KneeFootShinHipBackHamstringAnkleGroinThighShoulderNeckAbdomenlliotibial bandP€lvisOtherTotal

1O7 (213%l1O4 (20.7%lu(12.7%l58 (11.6%)48(5.2%l41(8.2%l37 V.4%)13 (2.6%)I (1.8%)6(1.2%)4(0.8%)2(0.4%)1(O.2%)1(O.2%le (1.8%)

502 0 oo.1 %)

66.0%75.O%94.2%74.59641.s%o

81.1o/ou.696

' Total (100.1 %) due to rounding all percentages to one d€cimal place.

more commonly affected by a variety of nonspecific injuriesthan was the hamstring musculature.

Initial Occurencrc of lqiuries. For each injury reported,subjects were asked to indicate whether they believed that theinjury had occurred as a direct result of participation inracewalking or whether the injury had occurred as a result ofsome other activity and had been aggravated or reinjured bysubsequent participation in racewalking. Table 2 shows thepercentage of injuries at each anatomic site that were not

124 Volume 33 o Number 2 o June 1998

associated with prior orthopaedic history: that is, injuriesrespondents assumed to have been a direct rcsult of participa-tion in racewalking. Our analysis has been restricted to thosesites that include at least SVo of all rcported injuries. Datagenerated from subsets that included only a handful of cases

appear to be of dubious value.In total, about four fifths of all injuries reported at the seven

most commonly injured sites were not associated with priororthopaedic history, but a closer examination of the data

reveals some interesting rends. For example, more than half ofthe injuries involving the back (58.5Vo) had been associatedwith prior orthopaedic history. However, most injuries to the

shin (94.2%), ankle (84.6%), and hamstring (8l.lVo) were notassociated with prior orthopaedic history. On the basis of these

observations, we inferred that many back pain sufferers "bringtheir injuries to the sport," but there appear to be cause-and-effect relationships between racewalking and many injuries tothe shin, ankle, and hamstring.

Severity of I4juries. Subjects were asked to designate thelevel of severity of each of the injuries that they had suffered,based upon the following scale:r I-evel L Pain only after exercise.o Level 2.Pun during and after exercise, but little change in

exercise patterns or daily activities.r Level 3. Pain resulting in changes in exercise patterns and

affecting some daily activities.o Level 4. Pain all the time, eliminating all exercise and

affecting many daily actiYities.Only l5.5%o of respondents reported more than two injuries,

and in most instances where more than two injuries werereported, the additional injuries were classified by respondentsas Level I (pain only after exercise). Therefore, we limitedsubsequent analysis to the most serious injury and the secondmost serious injury for subjects who reported two or moreinjuries (Fig 2). About half of all the injuries (49.5Vo) can beregarded as relatively trivial, since they created few or nochanges in exercise patterns or daily activities. Of the remain-

Level 1 Larel2 Level 3 leYel ISeverlty of Inlury

Fig 2. Distribution ot severity of all r€ported aniuries.

der, only l2.4%o were classified by respondents as Level 4injuries, which had a significant effect on exercise and dailylife. These observations reinforce the contention that racewalk-ing is a relatively safe activity. As indicated earlier, theracewalkers in our sample suffered an average of 0.156 injuriesper year. If only 12.47o of all injuries are l-evel 4, the averageracewalker will suffer one serious (kvel 4) injury every 51.7years!

Reladve Severity of lr{ury at Each Anatomic Site.Analysis of the severity of those injuries that subjects assumed

to have been sustained as the result of racewalking revealedsome interesting trends. Figure 3 shows the distribution ofinjury severity at the four anatomic sites wherc such injurieswere most fr,equently reported. Subjects indicated that mostinjuries to the shins had little or no effect on exercise patternsor daily activities and that only 63% were serious (Level 4).Conversely, over halfthe injuries to the knees, ankles, and feetresulted in changes to exercise pattems and daily activities(65.3% of knee injuries, 65.2% of the ankle injuries, and 6O%

of foot injuries were classified as l-evels 3 or 4).Medical Attention. A further insight into the relative

seriousness of injuries can be inferred from the fact that almostone third ofinjured subjects (3O.6Vo) did not seek any form ofmedical treatment even for their most serious injury. Of those

706050aoKnee ;m10

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706050

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L€Yel 1 Lsvel 2

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6o

oooo

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Lovel 2 Lavol 3 Lovol I

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L€vel 1 Levol 2 Level 3 L6Yel /t

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Level 1 Levol 2 Levsl 3 Lovol 4

Fig 3. Relatiye seyerity ot inluries reported at four anatomic

Level 3

Journal of Athletic Training 125

subjects who did seek treatment, some subjects sought medicaladvice from more than one source. In all, 343 sought medicalconsultations (Table 3). The specific treatments recommended

are listed in Table 4. It is apparent that only a limited numberof subjects sought attention from athletic trainers (6.4Vo),

which we assume is due to a lack of opportunities forracewalkers in the high school and collegiate settings. How-ever, we suggest that athletic trainers who have an interest inracewalking injuries should make local physicians aware oftheir willingness to accept refenals of injured athletes.

Perceived Causes of Iqiuries. Subjects were given theopportunity to attempt to explain the causes of their injuries.These data must be regarded with some reservations. However,in the absence of information about the precise circumstancesassociated with each of the injuries reported, it can be argued

that the subjects' perceptions might provide better insights thanthe researcher's or clinician's speculations.

For 225 of the 502 reported injuries (M.8Vo), subjects

believed that they could identify the cause of their injuries.Almost two thirds of all of these "accountable" injuries (146 :G.9%) were attributed to either a significant increase in the

amount of exercise that was done (97 = 43.17o) or postural oranatomic deficiencies (49 : 2l.8%o). Improper technique(29 : l2.9%o), improper shoes (19 : 8.4Va), and impropersurface (17 : 7.6Vo) were also reported. One or more subjectsalso attributed the cause of injuries to running on hills,insufficient stretching or warm-up, poor coaching, and pushingtoo hard during a race.

Cross-Tabulation Of Variables

We made an effort to establish a relationship between injurystatus and the variables examined in our investigation. Analy-ses were restricted to those injuries that were not associatedwith a prior orthopaedic history. That is, injuries that had beensustained before participation in racewalking and had subse-

Table 3. Medical Consultations Reported by 4O0 Racewalkers

Practitioner Frequency

Table 4. Treatments Prescribed as th€ Result ot ConsultationsListed in Table 3

Recommended Treatment Frequency

Reduced activityPhysical therapyMedicationComplete restSurgeryOther treatmentsNo treatmentTotal

83124'2%l68 (19.8%)55 (16.0%)45 (13.1%)45V.3%)

65118.4%l4 (1.1%)

343 (99.9%)'

OrthopaedistPodiatristChiropractorGeneral practitionerAthletic trainerPhysical therapistMassage therapistSports medicine MDMilitary physicianSports medicine clinicGoachKinesiologistInternistRheumatologistOsteopathNeurosurgeonTotal

105 (30.6%)82(23.9%l57 ('t6.6yo)44 (12.8Vo)

22 (6.4Vo)

18 (5.2o/o)

3 (0.e%)2(0.6%)2 (O.6yo)

2lO.6Vo)(O.3o/o)

(0.3o/o)

(O.3Yo)

(0.3%)(0.3%)(0.3%)

'Total (99.9%) due to rounding all percentages to one decimal place.

quently been aggravated or reinjured by participation inracewalking were excluded from the remainder of the analyses.

Results of a chi-square analysis indicated significant rela-tionships between injury status and three of the variablesexamined. These were age of subjects (P : .0001), the numberof training sessions in a typical week (P : .009), and theweekly training mileage (P : .02). Table 5 shows the means

and standard deviations for each of these three variables forboth injured and noninjured subjects.

Age and Injury. Figure 4A shows the distribution of ages ofsubjects in this investigation. Participation peaks in the range

of 30 to 39 years of age and declines steadily thereafter. Figure48 shows the percentage of individuals in each of the age

groups who reported injuries. The greatest proportion ofinjuries was reported by individuals under the age of 3O (42

injured out of 57 subjects : 73.7%), and the proportion ofinjured participants tends to decline thereafter.

Interpretation of this observation is open to some specula-

tion. However, on the basis of the mean ages of injured and

noninjured participants (4O|7 and 48-2 years ofage, respective-ly), it might be argued that those participants who are prone todiscomfort and injuries are more likely to give up the sportearlier than those who are injury free. In this sense, olderparticipants can be regarded as having "survived" by virtue ofgenetic factors such as mechanically sound biomechanics andby behavioral factors such as prudent training practices. Thishypothesis could be tested by examining the injury history ofa sample of retired racewalkers.

Frequency of Training. Figure 5 shows the proportion ofinjured participants grouped on the basis of the number oftraining sessions in a typical week. Less than half the groupwho trained three or fewer times per week had sufferedinjuries, while about two thirds of the individuals who trainedsix or seven times per week had been injured. These observa-

Table 5. Means (! Standard Devlation) of Age, TrainingFrequency, and Average Weekly Mileage for NoninjuredRacewalk€rs and Racewalkers Who Suftered InjuriesWith No Prior Orftopedic History

Training AverageAge M (sessionVwk) (weekly mileage)

343 (100%)fnjured (n = 200) 4O.7 + 13.2Noninjured (n = 143) 48.2 * 15.3

5.1 * 1.4 32.3 * 17.94.7 + 1.6 26.7 * 18.4

126 Volume 33 o Number 2 o June 1998

12-29 30-39 40-49 50-59 60-69 70-84

Age grouP

Age group

Fig 4. A Age distribution of 'O racewalkers. B, Percentage ofinjured racewalketr an each of ttp age groupe shown in A.

100

1-3 4-5 6-7FrequencY of training

Flg 5. Number of training days each week and corespondingnumber of iniured participants,

tions appear to reflect cumulative stress disorders. It is widelybelieved that the potentially injurious effects of mechanicalstress are cumulative, but that days of rest will allow physio-logic processes to repair microtrauma to the musculoskeletalsystem.

Weekly Training Mileage. The average weekly trainingmileage reported by injured subjects (32.3 miles) was greater

than the mileage reported by uninjured subjects (26,7 miles).Figure 6 indicates that the greatest proportion of injuredindividuals occurred among the group whose members accrued

more than 50 miles each week, and the smallest proportion ofinjured individuals occurred among those who restrict weeklytraining to 15 miles or less. This observation is consistent withthe conclusion of Powell et al,lo who reviewed three epidemi-ologic studies of running injuries and reported, "Of all the

possible causes of injury, the number of miles run per week ismost clearly associated with the incidence of running injuries."

Discriminant Analysis of Variables Related to Iniury

We used a stepwise discriminant analysis to determinewhich linear combination of variables examined would bestdiscriminate between injured and uninjured racewalkers. Re-

sults indicated that years of participation in racewalking (D,the duration of the average training session (D), the frequencyof training sessions in a typical week (O, and age (A) were

significant (P < .05). A model for the prediction of injury inracewalking was established: D : 0.28(D + 0.27(D) +M4(n - 0.83(A)

However, indicators of practical significance, including thecanonical correlation coefficient (0.32) and Wilks lambda(0.90), demonstrated little utility for the model. In fact, the

above relationship would conectly predict membership ineither the injured group or uninjured group in only 64-l%o ofcases. In practical terms, such a model is not a great deal moreeffective than prediction based upon coin tossing, which wouldcorrectly predict group membership in 5O% of cases. The currentmodel is therefore of limited value to the researcher or clinician.

1-15 16-49 50-100Weekly tralnlng mlleage

Fig 6. Percentage of racewalkers reporting iniuries in each of thre€groups based on weekly training mlleage.

't20

100

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B

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12-29 30-39 40-49 50-59 60-69 70-8E

Journal of Athletic Training 127

DrscussroN

Our investigation provided demographic data that are ofinterest to the athletic training community. Specifically, overallparticipation peaks among the 30- to 39-year-old age group.

This finding is likely to reflect the passage of the "age wave"of baby boomers in our society, but the total number ofparticipants under the age of 20 years (16,4Vo) revealed that

racewalking appears to have limited appeal to younger indi-viduals. [n a study conducted on behalf of the AthleticFootwear Association,rt Ewing and Seefeldt questioned more

than 8,000 young people and found that there was a steady

decline in interest in track sports berween the ages of l0 and l8years. Subjects indicated that the mean reason for participationwas "having fun." In commenting on the sociologic implica-tions of Ewing and Seefeldt's observations, Danishll stated,

"What is enjoyable for individuals will change with age. Eventhough boredom or anxiety may produce a drop-out, the

individuals may well turn to the sarne or another sport later on,

especially if they can find something important about them-selves in the activity."

On the basis of our data, it would appear that racewalkinghas exemplified this state of affairs. The cross-training habitsof many participants are clearly appropriate for goals otherthan success in competition, and long-term commitment to the

sport is cornmon. The widespread use of footwear that was

designed for activities other than racewalking may be indica-tive of the limited selection of racewalking shoes available.However, this observation could also indicate that manyparticipants have a relatively informal attitude to the activitywhen compared with many dedicated runners and dance-exercise enthusiasts, who tend to be fiercely loyal to specificmodels of activity-specific shoes.

Participants appear to be well informed about current sportsmedicine practices. The injury-prevention benefits of stretch-ing have not been objectively demonstrated, but stretching, onthe basis of anecdotal evidence, is widely advocated by sportsmedicine professionals and practiced by most racewalkers.Most medical consultations appear to have been sought withinthe framework of credible medical resources. Racewalkers'perceptions of the causes of their injuries are also consistentwith the conclusions of researchers who have studied injuriesto runners and dance-exercise participants and instruc-tors.7,8,r2.r3

The injury rate in the sport is low by any standards, and thenature and location of injuries to the lower extremity aresomewhat consistent with the biomechanics of the activity.Fentons found that the mediolateral forces on the feet ofracewalkers were significantly higher than for a normal walk-ing gait. Paynera attributed these relatively large mediolateralforces in racewalking to the straightening of the supporting legand the compensatory lowering of the opposite hip andipsilateral shoulder in order to maintain a linear progression ofthe center of mass. Corrallo et al (V. Corrallo, L. Downes, K.Hogan, T. King, K. Larsen, J. O'Dwyer, and A. Peck, unpub-

lished data, 1983) found that, unlike normal walking gait, there

was no knee flexion during midstance.

The characteristic rolling gait of racewalking is mandated bythe rules, which specify that at least one foot should be incontact with the ground at all times and that the knee should be

extended when the corresponding foot makes first contact withthe ground. Although a significant change in the first of these

rules would predictably reduce some mechanical sEess on thelower extremities, it is likely that such a fundamental change

would radically alter this traditional competitive activity. Inactual fact, high-speed cinematographic analysis has shownthat many racewalkers do incorporate an unsupported phase

during competition,l5 but that the practice cannot be detected

using only the visual acuity of judges. Furthermore, on thebasis of the incidence of injury indicated by the curentinvestigation, there is little compelling rationale for advocatingsuch an extreme change in the rules. However, some writershave recommended that changes should be made in the rulegoveming knee extension during initial impact with theground.l6

Finally, even with the relatively large sample of subjecs thatwas used in our investigation, we were unable to generate a

model that would provide good prediction of injury status onthe basis of the variables examined. Such a conclusion isconsistent with similar attempts to objectively identify factorsthat cause injuries to runners.lo

In an attempt to provide a systematic approach to theidentification of factors that contribute to injuries, Nigg et allTproposed a system that classifies the sources of potentiallyinjurious mechanical stresses into a number of categories and

subcategories. These include external factors, (such as thevarious characteristics of shoes, surfaces, and the environ-ment), internal factors (such as pre-existing orthopaedic status

and various aspects ofpsychological status), technique (includ-ing the influence of history of instruction and experience), and

training habits. However, the authors indicated that even witha systematic approach, there may be additional factors in-volved, and it is likely that there are complex interactionsbetween the various factors. On the basis of research involvingrunning injuries, Powell et alro concluded that a number of thefactors widely believed to be causative of such injuries havenot been objectively demonstrated to be strongly related toinjury status. Furthermore, human populations cannot bereadily subjected to experimental controls, and so it is inevi-tably either impractical or impossible to account for allpotentially causative factors. A great deal more systematicresearch must be completed before the athletic training com-munity can confidently recommend consistently effective in-jury prevention procedures in sport in general and racewalkingin particular.

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128 Volume 33 o Number 2 o June 1998

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3. Subotnick S. The Rwning Fut hctor.

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4. Palarruchuk R. Racewalking: a not so injury froe sporr In: Rinaldi R&Sabia MI. eds. Spons Medicitu '80. ML Kisco, NY: Fuuua hblishingCo; 1980:19-20.

5. Fenton RM. Rrcewalkiog gmund a*tion forces. ln: Terauds J, Bartlrcls

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