Br J Sp Med 1994; 28(2)

Athletic footwear affects balance in men

Steven Robbins MD*, Edward Waked PhDt, Gerard J. Gouw PhD(eng)* and JacquelineMcClaran MD CFPC§*tlDepartment of Mechanical Engineering, Concordia University, *tDivisions of Geriatric and ExperimentalMedicine, Montreal General Hospital, *§McGill University Centre for Studies in Aging, 5McGill UniversityFaculty of Medicine and 5Division of Geriatric Medicine, Montreal General Hospital

Stable equilibrium during locomotion is required for bothsuperior performance of sports and prevention of injuriesfrom falls. A recent report indicated that currentlyavailable athletic footwear impairs stability in older men.Since this discovery, if confirmed, seems important toboth competitive athletes and the physically active generalpublic, we performed an experiment using similarmethods on a younger population. We tested thehypothesis that midsole thickness is negatively, andhardness positively related to dynamic equilibrium, in 17healthy adult men (mean(s.d.) age 33(11.13) years) via abalance beam method. Subjects walked along a 9-m longbeam at 0.5m sl once barefoot and six times wearingidentical pairs of experimental shoes which differed onlyin midsole hardness and thickness which spanned therespective ranges currently available in footwear. Fallsfrom the beam (balance failures) were quantified. Balancefailures varied significantly in relation to midsole hard-ness and thickness, and there was a strong trend towardinteraction of these variables (P = 0.09). Midsole hardnesswas positively related to stability, and midsole thicknesswas negatively related, which confirms the previousreport. Hence, shoes with thick-soft soles, similar tomodem athletic footwear and 'walking shoes', destabilizemen, and shoes with thin-hard soles provide superiorstability. The pair with the poorest stability (A 15 - thick;12.34 balance failures per 100 m) produced 217% morebalance failures than those associated with the beststability (A 50 - thin; 3.89 balance failures per lOOm).Since most types of athletic footwear and many othershoes incorporate midsoles with hardness and thicknessassociated with poor stability, we conclude that bothathletic performance and public safety could be enhancedthrough stability optimized footwear.

Keywords: Equilibrium, stability, balance, footwear,athletic footwear, shoes

Maintenance of stable equilibrium during locomotion(walking and running) applies to physical activityfrom two perspectives - athletic performance andinjury. Athletic performance must be influenced

substantially by an athlete's stability, however, asidefrom obvious poor athletic performance shown bythose with significant equilibrium impairment, suchas vestibular disorders', and induced instability viacalorics2, it has not been quantified.With respect to health, falls and their consequences

are the most significant hazard associated with poorstability. Although falls in the older age group havelife threatening consequences3-', falls during locomo-tion in younger individuals account for considerablemorbidity.

Falls are usually elicited by correctable extrinsicfactors that produce disequilibrium, acting upon theindividual's inherent stability, which declines withage in adults8 9. Extrinsic factors include en-vironmental causes of instability, such as slipperysurfaces, pavement irregularities, loose rugs, poorlighting, footwear, and obstacles in passageways, toname a few. Most progress in preventing falls willcome from identifying and mitigating environmentalcauses of instability3.Footwear that incorporates expanded polymer

foam of a certain range of thickness and hardness,which includes most commercially available athleticfootwear, and presently popular 'walking shoes', hasrecently been reported substantially to impair equilib-rium in older men. For example, these authors haveshown that differences in fall frequency from abalance beam varied by an amazing 128%, whencomparing footwear associated with the best stabilitywith that of the poorest8. Since stability differences ofthis magnitude must have major health and athleticperformance effects, products providing poor stabil-ity are currently being marketed to the general publicspecifically for use in performing physical activity(walking shoes and athletic footwear), and no safetystandards are in force that can provide the publicwith relative stability with the use of these products.Further examination of the relation between footwearsoles and stability seems justified.The previous report examined footwear midsole

hardness and thickness exclusively in an older malecohort8. It seems unwise to assume that their resultsapply to the general population without testing ayounger group. Accordingly, the experiment thatfollows tests the hypothesis that stability in youngermen is influenced by footwear midsole hardness andthickness.

Br J Sp Med 1994; 28(2) 117

Address for correspondence: Dr Steven E. Robbins MD, 800 ReneLevesque West Suite 2010, Montreal, Quebec, H3B 1X9, Canada

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MethodsWe adapted the balance beam testing method for usein this experimentl0'-4. The narrow width of thebeam places a fixed constraint on the strategy ofmoving the ipsilateral (the side towards which thecentre of mass is displaced) leg laterally to maintainstable equilibrium. The requirement of forwardlocomotion on the beam at a constant velocity, placesa constraint on other behavioural strategies humansuse to retain and regain stable equilibrium duringlocomotion (e.g. prolongation of the double supportphase; reduced forward velocity; reduced stridelength). We placed the beam on the floor, andpositioned a technician close to the subject, so thatfalls to the floor are prevented when subjects fail tobalance on the beam (balance failures).

ApparatusAn extruded aluminium beam (cross-section outerdiameter width 7.8cm, height 3.9cm; length 9m)rested on 4-mm thick pads of carbon rubber (in orderto reduce risk of beam movement across the floor),which contacted the floor. Beam width was selectedso as to be wider than the soles of the experimentalshoes. All subjects wore glasses which were modifiedby adding translucent adhesive tape to the lowertwo-thirds of both lenses, so as to prevent subjectsfrom seeing their feet clearly and approximately 2mof the beam in front of them. This method of visualinformation deprivation was based on a pilot studywhich showed that this technique produced adequatevariation in balance failure frequency with subjects ofthe age used in this experiment, when combined withthe width of beam used, and the relatively slowforward velocity. We feel that this method of visualinformation attenuation is valid insofar as duringnormal locomotion humans do not look at their feetor immediately in front of them when they normallywalk or run. The relatively long beam length waschosen in preference to more typical shorter beams inorder to reduce time lost by turning and remountingthe beam. The floor adjacent to the beam was markedat 1-m intervals to aid the technician in estimatingdistance travelled by subjects to points of balancefailures.

SubjectsA total of 17 subjects participated in the study whowere of mean(s.d.) age 32.6(11.13) years (range 19-50years) and mean(s.d.) height 176.4(4.95) cm (range166.4-185 cm); mean(s.d.) weight 72.2(10.59) kg(range 56.8- 102.3kg). Fifty years was chosen as themandatory upper age limit because a previous reportand a pilot study we performed indicated thatstability in men decreases thereafter. The compulsorylower limit of 18 years was selected to avoidontological changes in stability. This experiment waslimited to men in order to circumvent selection ofsubjects by foot size, because available shoe sizescould properly fit most men, but would fit a smallpercentage of women. Additional subject selectioncriteria were absence of disabilities influencing abilityto walk, and no history of frequent falls.

Testing locationThe room was well lit and devoid of furnishingsbarring experimental apparatus. The room wasisolated so as to subdue auditory and visualdistractions that might disturb subjects' concentra-tion.

Hardness testingA scale durometer (Shore) hardness testing wasperformed according to methods set forth by theAmerican Society for Testing of Materials (StandardD 2240 - Standard Test Method for Rubber Property -Durometer Hardness)'5. A larger value of A scalehardness connotes greater hardness.

Testing conditionsThere were seven testing conditions - barefoot andsix different pairs of experimental footwear. Thefootwear was similar to current running shoes -uppers fabricated from suede leather and nylonfabric; cement lasted; heel flare of 20°; outersole 5-mmthick carbon rubber (Figure 1). For each size, therewere six different pairs of experimental shoes, whichdiffered in midsole hardness and thickness, theexperimental variables. The midsoles were composedof a uniform expanded polymer foam of hardnessA 15, A 33 or A 50. These hardness choices werebased on a pilot study which sampled currentfootwear. A 15 approximated the softest midsole,whereas A 50 corresponded to the hardest, and A 33represents the mean. The most commonly usedmidsole hardness in current footwear that uses thesematerials was A 25. For each midsole hardness, therewere two midsole thicknesses. The thinner midsole

I cm[I

MMidsole /FZ Outersole

Figure 1. Dimensions of sole materials of thick and thinshoe used in this experiment. Outer sole (lowest layer)was 0.5-cm carbon rubber. Midsole (middle layer betweenoutersole and upper) was composed of expanded polymerfoam of hardness A 15, A 33 or A 50. Hardness measuredby Shore durometer using the A scale. The upper, whichencloses the foot, was identical in all shoes used.

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was 13-mm thick at the heel, and 6.5-mm thick at thesite subtending the metatarsal-phalangeal joint. Thethicker shoe's midsole was 27mm at the heel and16mm under the metatarsal-phalangeal joint. Thesethicknesses correspond to the respective thinnest andthickest midsoles measured in a survey of currentlyavailable footwear of this construction. The shoeswith thin midsoles and A 50 hardness resembleconventional leather or hard rubber walking shoeswith respect to sole hardness and thickness.

Testing procedureSubjects were told that the purpose of the experimentwas to relate footwear features to balance. Theirconsent was obtained according to guidelines setforth in the Declaration of Helsinki of the WorldMedical Association. Subjects practised beam walk-ing a minimum of ten, and maximum of 20 passes, bytheir choice. In order to pace subjects at a predeter-mined velocity, and to prevent falls to the ground, atechnician walked backwards with the beam betweenhis feet, at a constant velocity, 1 m in front of thesubject. The rate of walking was fixed at 0.5 ms-1,which was shown in a pilot study to be a relaxedwalking pace with subjects of this age group. Subjectswere instructed not to reduce the forward velocityeven if it would help prevent balance failures. Uponfalling off the beam, subjects were required to walk tothe end of the beam before remounting rather thanrecommencing at the fall site (Figure 2).There were ten passes down the beam for each

testing condition. The distance from the beginning ofthe pass to the site of balance failure was estimated tothe nearest metre and recorded. The order ofpresentation of the different shoes and walkingbarefoot followed a unique random series for each

subject. After completion of all test conditions,subjects were asked to identify the most comfortableshoe, as well as any uncomfortable ones.

Data analysisStrength of relations among the seven test conditionsand balance failure frequency were evaluated bytwo-factor analysis of variance for repeated mea-sures. The two factors were midsole thickness (thin,thick) and midsole hardness (A 15; A 33; A 50).When significant F ratios were obtained, the relation-ships between specific pairings of conditions wereassessed by post hoc paired t tests. Pearson productmoment correlation coefficients were used to assessthe relationship among variables of age, height andweight and balance failure frequency. An alpha levelof 0.05 was used as the criterion for all tests ofstatistical significance.

Results

Balance failure frequency as a function of subject's age.There was no significant relationship between ba-lance failure frequency and subject's age (r = 0.04;P = 0.33).

Balance failure frequency as a function of subject's height.There was a small but significant negative relation-ship between balance failure frequency and subject'sheight (r = -0.21; P = 0.01). The linear regressionobtained is given by the following equation:

y= -0.35x + 69.3

where x = subject height in cm

y = balance failures per 100m of beam walking

Figure 2. Subjects walk forward and technician backwardstraddling the beam. Subject is told to maintain a fixeddistance between himself and the technician. The techni-cian paces the subject at a velocity of 0.5ms-1. Thetechnician is sufficiently close to the subject so as toprevent subjects from falling to the floor after they fallfrom the beam.

Balance failure frequency as a function of subject's weight.There was no significant relationship between ba-lance failure frequency and subject's weight(r = -0.07; P = 0.23).

Balance failure frequency as a function of test condition(Figure 3 and Table 1).Analysis of variance for repeated measures indicateda statistically significant main effect for midsolethickness (F(1,16) = 11.04; P =0.004), and midsolehardness (F(2,32) = 11.12; P= 0.0002). The interac-tion effect between midsole thickness and midsolehardness was not statistically significant, althoughthere was a trend towards interaction (F(2,32) = 2.48;P=0.09).

Post hoc t test revealed a statistically significanteffect for midsole thickness (thin mean = 5.79 balancefailures per 100 m; thick mean = 8.94 balance failuresper 10Gm; t = 3.62; P = 0.0003). In addition, signifi-cant differences between hardness A 15 and 33(t = 2.83; P = 0.003), A 33 versus A 50 (t = 4.38,P = 0.0001) were obtained using post hoc t tests, and astrong trend toward differences between A 33 andA 50 (t =- 1.55, P = 0.06).

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15

EC)CD

00.

(Aen

a)

t)

m

10

5

O I A

15 33 50

Midsole hardness (Shore A)

Figure 3. Plot of balance failures (falls from the beam) as afunction of midsole hardness for two sole thicknesses andbarefoot conditions. Values are mean(s.e.). *, thinmidsoles; A, thick midsoles; *, barefoot

Table 1. Balance failure frequency as a function of test conditions

Hardness Thickness Mean(s.e.)

15 thin 7.03(1.70)33 thin 6.46(1.68)50 thin 3.89(1.03)*15 thick 12.34(2.19)t33 thick 7.43(1.91)50 thick 7.04(2.18)Barefoot 10.79(2.19)t

*Significantly lower balance failure frequency than any other testcondition; tsignificantly higher balance failure frequency thanany other test condition; tsignificantly higher balance failurefrequency than five of six experimental shoe conditions

Balance failures with experimental footwear in relation tobalance failures when barefoot.There were significantly more balance failures whenbarefoot as compared with overall balance failuresfrequency with experimental footwear (mean bare-foot = 10.78; mean footwear = 7.01; (t = 2.79,P = 0.006) ).

Balance failure frequency as a function of order ofpresentation of conditions.Balance failure frequency was significantly higherwith the first testing condition encountered duringthe session compared with any that followed(F(14,98) = 4.42, P = 0.0001). There was no othersignificant difference in balance failure frequency inrelation to presenting order.

Superior comfort as a function of experimental footwearmidsole hardness and thickness.Fifteen subjects judged shoes with midsoles A 15 -thick, and two subjects chose shoes with midsolesA 33 - thick, to be most comfortable. None choseshoes with other midsoles.

Discussion

Postural stability has been assessed either by indi-vidual tests or via test profiles. The profile method isexemplified by Fregley, whose 'Test Battery' wasoriginally developed to infer relative stability ofindividuals with vestibular disorders1. Profileapproaches have limitations. The selection of testsused in profiles follows no logical plan, other thanusage of methods in previously published reports,and adequacy in identifying certain individuals withobvious balance disorders. Tests included in profilesvary in validity, repeatability and sensitivity. The'score', which is the unweighted average of thevarious tests, may poorly reflect actual stability ofhumans under a specific condition. Since we wereinterested exclusively in the situation when healthyhumans normally fall, use of the profile methodconcerned us greatly - we chose to use an individualmeasure of stability, which required selection of asingle method that was the most valid, sensitive andrepeatable of all measures that have been used to testhumans. Following selection of test type, furtherwork was performed refining it (dealt with in aprevious report)8. Method selection criteria deservemention. We believe the method chosen, a modifiedbalance beam method, to be the most valid inunderstanding stability in relation to human falls fora number of reasons. Unlike many methods, thetask-specific constraints that the balance beam placeson an individual attempting to retain or regain stableequilibrium resembles conditions associated withhuman falls in the natural condition, because fallsalmost always occur under environmental stress(usually impaired foot-ground contact, and duringlocomotion)16. Furthermore, the scientific literaturehas shown that the balance beam method is the mostconsistent in selecting those groups with neurologicalbalance disorders, conditions known to causefalls1',2 12

This can be contrasted with measures of sway, astability measure currently in fashion7' 18. Swayincreases not only in individuals with poor stability,but also in those possessing superior stability whenrelaxed and unstressed17. Therefore it fails todistinguish the most stable from the least stableindividuals. Further, sway is measured when stand-ing rather than during locomotion when most fallsoccur.Other popular methods infer stability of indi-

viduals via responses to provoked instability, by suchmeans as tilting platforms or physically movingsubjects18. These methods seem to lack validity forour purposes because they fail to examine subjectsduring locomotion, and the methods used to provokefalls poorly resemble initiation of most natural falls.

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Perhaps our specific method's greatest attractionhas been its repeatability. Our method producesresults with the lowest standard error of any stabilitymeasure reported in the literature to date. Forexample, through pooling data from the presentreport and a previous one which used this method,we found that the standard error of the mean ofbalance failures was well under 4% 68 (1.76 balancefailures per 100 m). In addition, the method isexceptional in terms of reliability. As an example, 13older subjects were retested on the balance beam 2years after their first testing session in a differentlaboratory, by a different technician. The reliabilitycoefficient was found to be a remarkable 0.91.The results of the present experiment essentially

confirm the results of the earlier report8. There weresignificant differences in stability in relation tomidsole thickness and hardness in the patternconsistent with our hypotheses. Exchanging shoeswith thin midsoles for thick-soled ones, increasedbalance failure frequency by 54.3% (thin mean = 5.80balance failures per 100m; thick mean = 8.94 balancefailures per 100m). Furthermore, changing from thehardest to softest midsoles increased balance failurefrequency by 77.1% (mean A 15 = 9.69 balancefailures per 100 m; mean A 50 = 5.47 balance failuresper 100m). Substituting shoes with the thickest andsoftest midsoles (poorest stability) for those incorpor-ating the thinnest and hardest midsole (best stabil-ity), increased balance failure frequency by a remark-able 217%. There was a strong trend towardinteraction between these two variables (P = 0.09).Clearly there is a positive relation between midsolehardness and stability, and a negative relationbetween midsole thickness and stability.The data from the present experiment suggest

performance could be improved if footwear usedwere optimized for stability. For example, diving andgymnastics, sports which stress balance consider-ably, are usually performed with bare feet. Our datashowed 10.79 balance failures per 100m whenbarefoot, whereas there were 3.89 balance failures per100m with the best shoe. If such a shoe were used byindividuals performing these activities, the 64%decrease in balance failures would probably bereflected in improved performance due to improvedstability. It should be noted the present experiment'sbest shoe was not an optimal shoe because thepurpose of the present experiment was to span therange of sole thickness and hardness in availablefootwear rather than optimize these factors. Throughoptimization, it should be possible to produce a shoecapable of reducing balance failure frequency by farmore than 64%.Furthermore, sports such as football, basketball

and racquet sports stress balance greatly. Sincehardness and thickness of midsole material used inthe soles of virtually all available footwear issuboptimal according to data from the presentexperiment and the previous report, improvedstability, hence performance, could be anticipated inthese sports with stability optimized shoes. We arepresently testing stability in athletes using currentlyavailable commercial sports shoes with the goal ofachieving a more stable shoe.

A comparison of the results of the present report,which used a young population, with those of aprevious report employing an older cohort, ispossible only to a limited extent8, since experimentalprocedures in both studies differed slightly. Notwith-standing this, the results indicate that the oldersubjects may be less affected by thick soles thanyounger individuals. For example, switching fromthin to thick soles increased balance failures by 54.3%in the young (5.80 balance failures per 100m to 8.94balance failures per 100 m), but raised balance failuresby 21.3% in the elderly (7.60 balance failures per100m to 9.23 balance failures per 100 m). By contrast,when considering sole hardness, changing from A 50to A 15 in hardness increased balance failure frequ-ency by 77.2% with the young (A 50 = 5.46 balancefailures per 100m; A 15 = 9.68 balance failures per100 m), but by 93.2% in the older population (A 50 =6.15 balance failures per 100m to 11.88 balancefailures per 100m). Therefore changes in hardnessaffected stability more in the elderly than the young.With 88.2% of the subjects selecting the shoe with

A 15 - thick midsoles as most comfortable, there issupport for the notion that midsole thickness ispositively related to comfort and hardness is nega-tively related to comfort. However, none of theexperimental shoes was judged uncomfortable. Sincethe shoe that imparted the greatest comfort also wasresponsible for the greatest instability, it seemssensible to caution individuals against optimizingfoot comfort through choosing shoes with thick andsoft midsoles. Relatively comfortable shoes withthin-hard midsoles should be preferred.The present experiment does not identify the

material property of expanded polymer foam, themain constituent of athletic footwear soles, thatdestabilizes. It is known that ankle motion in themedial-lateral plane is negatively related to midsolematerial hardness (soft soles cause increased anklemovement), caused by sole compressible materialbeing eccentrically loaded (load applied near peri-meter) during human locomotion (the lateral aspectof the heel is usually the point of first contact). Webelieve that these rapid ankle movements produce aconfusing peripheral signal resulting in poor sense ofactual ankle position (impaired proprioception).Ankle position sense is thought to be important inmaintaining stable equilibrium in humans.Another material property of midsoles that may

contribute to instability is sensory insulation causedby expanded polymer foam. This sole material doesnot allow the plantar surface to deform from highamplitude localized vertical and horizontal loads. Wehave hypothesized that subjects underestimate theload they are experiencing and tend to overloadduring locomotion8 19. Similarly, sensory insulationcaused by thick-soft midsoles may make individualsunable to judge plantar pressure distribution. Plantarskin sense is known to contribute to stable equilibriumin humans. As far as preventing injuries to thegeneral public, since most athletic footwear andmany types of shoes marketed for casual use haveyielding layers underfoot composed of material lessthan A 33 hardness - hardness that this experimenthas shown is associated with suboptimal stability -

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there can be little doubt user stability could beimproved, and falls prevented, if safety standardsrestricted footwear midsole thickness and requiredthe use of harder materials.To summarize, footwear with thick-soft soles, in

the range of hardness and thickness seen in mostcurrent athletic footwear, and other footwear such as'walking shoes', destabilize men. Since impairedstability worsens athletic performance, optimizedfootwear would have an anticipated benefit tocompetitive athletes. In terms of health, these datasuggest a need for safety standards for footwear toprotect users from falls and their consequences.

AcknowledgementsThis work was supported in part by the Natural Sciences andEngineering Research Council of Canada Grant OGPIN 013, andthe Helen McCall Hutchinson Clinical Gerontology Scholarship.We thank ASICS Corporation for supplying the custom-madefootwear which was used in this experiment.

References1 Fregly AR. Vestibular ataxia and its measurement in man. In:

HH Kornhuber, ed. Handbook of Sensory Physiology: VestibularSystem, New York, USA: Academic Press, 1974: 321-60.

2 Fregly AR, Graybiel A. Labyrinthine defects as shown byataxia and caloric tests. Acta Otolaryng 1966; 69: 216-22.

3 Tideiksaar R In: BE Gray, ed. Slips, Stumbles and Falls:Pedestrian Footwear and Surfaces. Philadelphia, Pennsylvania,USA: American Society for Testing and Materials, 1990:17-27.

4 Wolf-Klein GP, Silverstone FA, Basavaraju N. Prevention offalls in the elderly population. Arch Phys Med Rehab 1988; 69:689-91.

5 Gabell A, Simons MA, Nayek USL. Falls in the elderly:predisposing causes. Ergonomics 1985; 28: 965-75.

6 Tinetti ME, Speechely M, Ginter SF. Risk factors for fallsamong elderly persons living in the community. N Engl I Med1988; 319: 1701-7.

7 Wasson JH, Gall V, McDonald R. The prescription of assistivedevices for the elderly: practical considerations. J Gen Int Med1990; 5: 46-54.

8 Robbins SE, Gouw GJ, McClaran J. Stability in older men inrelation to footwear midsole hardness and thickness. J AmerGeriatr Soc 1992; 40: 1089-94.

9 McMahon TA, Valiant G, Frederick EC. Groucho running. JAppl Phys 1987; 62: 2326-7.

10 Assaiante C, Marchand AR, Amblard B. Discrete visualsamples may control locomotor equilibrium and foot position-ing in man. J Mot Beh 1989; 21: 72-91.

11 Newsome BD, Brady JF, Gobile GJ. Equilibrium and walkingchanges observed at 5, 71/2, 10 and 12 RPM in the revolvingspace simulator. Aerospace Med 1965; 36: 322-6.

12 Auxter DM. Proprioception among intellectually typical anddifferentially diagnosed educatable mentally retarded boys.Perc Mot Skills 1965; 21: 751-6.

13 Horvat MA. Effect of a home learning program on learningdisabled children's balance. Perc Mot Skills 1982; 55: 1158.

14 Heath SR The military use of the rail-walking test as an indexof locomotor coordination. Psych Bull 1943; 40: 282-4.

15 American Society for Testing and Materials. Standard testmethod for rubber property-durometer hardness. Annual BookofASTM Standards, Philadelphia, Pennsylvania, USA: ASTM,1988, 09.01: 596-600.

16 Warren WH, Young DS, Lee DN. Visual control of step lengthduring running over irregular terrain. J Expt Psych 1986; 12:259-66.

17 Wober C, Baumgartner C, Deecke L. Stabilizing anddestabilizing effects of vision and foot position on body swayof healthy young subjects: a posturographic study. Eur Neurol1989; 29: 241-5.

18 Era P. Heikinen E. Postural sway during standing andunexpected disturbance of balance in random samples of menof different ages. J Geront 1985; 40: 287-95.

19 Robbins SE, Gouw GJ. Athletic footwear: unsafe because ofperceptual illusions. Med Sci Sports Exerc 1991; 23: 217-22.

IX th EUROPEAN CONGRESS ON SPORT PSYCHOLOGY

Integrating Laboratory and Field Studies in Sport Psychology

4-9 July 1995Bruxelles, Belgium

The Congress will include:

* general lectures * interactive poster sessions * symposia with selected speakers

Venue: Universitd Libre de Bruxelles, Institut de Sociologie, avenue Jeanne 44, B-1050 Bruxelles

Languages: French, Dutch, English (no simultaneous translation will be provided)

Registration Fees: Before 15 March 1995 After 15 March 1995

Participants 7.000 BEF 9.000 BEFProceedings 2.000 BEFStudents and accompanyingpersons 3.000 BEF 4.000 BEF

For more information contact: Mrs M Plasch, IX th FEPSAC CONGRESS '95ISPEK - U.L.B.

av. P Hdger 28 (CP 168), 1050 Bruxelles, BelgiumTel: 32 2 650 21 80Fax: 32 2 650 31 14

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