Biomechanical measurements of human impacts in basketball

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1 Loughborough University Institutionl Repository Biomechnicl mesurements of humn impcts in bsketbll This item ws submitted to Loughborough University's Institutionl Repository by the/n uthor. Cittion: HALKON, B.J.... et l, Biomechnicl mesurements of humn impcts in bsketbll. Procedi Engineering, 72, pp Additionl Informtion: This is n Open Access Article. It is published by Elsevier under the Cretive Commons Attribution Non-Commercil-No-Derivtive 3.0 Licence (CC BY-NC-ND 3.0). Metdt Record: Version: Published Publisher: c Elsevier Rights: This work is mde vilble ccording to the conditions of the Cretive Commons Attribution-NonCommercil-NoDerivtives 3.0 Unported (CC BY- NC-ND 3.0) licence. Full detils of this licence re vilble t: Plese cite the published version.

2 Avilble online t ScienceDirect Procedi Engineering 72 (2014 ) The 2014 conference of the Interntionl Sports Engineering Assocition Biomechnicl mesurements of humn impcts in bsketbll Benjmin Hlkon *, Sén Mitchell, Thoms Pyne, Jorge Crbo b Wolfson School of Mechnicl nd Mnufcturing Engineering, Loughborough University, Loughborough, Leics., LE11 3TU, UK b Nike, Inc., One Bowermn Drive, Beverton, OR , USA Abstrct Despite significnt dvnces in mterils nd mnufcturing techniques pplied to sports protective equipment in recent yers, sports injuries due to impct, contusions in prticulr, continue to occur. In this pper, test methodology imed t collecting dt from lbortory-simulted humn-on-humn impcts in Bsketbll is presented. The study ws executed in three stges with dt being collected from: i) humn on instrumented bg; ii) impctor on instrumented bg nd iii) impctor on instrumented humn impcts. In ll cses, high-speed video nd/or kinemtic motion dt cpture systems were used to obtin prmeters such s inbound/outbound velocities, contct durtions while resistive ink technology pressure sensing films were used to estimte prmeters such s pressure distributions, pek pressures, contct res, impct forces. Elite-level thletes were used in ll humn trils to ensure tht impct techniques nd levels representtive of the elite gme were obtined nd tht tolernce to impcts ws similrly representtive. Two common strikes were simulted: knee on thigh nd elbow on rib/torso. Five prticipnts were used to collect the humn-on-bg dt while 12 prticipnts were used to collect the impctor-on-humn dt. Between three nd five impcts per scenrio were performed to enble noise verging nd, importntly, likely injurycusing outlier cpture The Published Authors. by Published Elsevier Ltd. by Elsevier This is n Ltd. open ccess rticle under the CC BY-NC-ND license ( Selection nd peer-review under responsibility of the Centre for Sports Engineering Reserch, Sheffield Hllm University. Selection nd peer-review under responsibility of the Centre for Sports Engineering Reserch, Sheffield Hllm University Keywords: Bsketbll; humn impct; force; pressure; velocity; Tekscn; CODA * Corresponding uthor. Tel.: ; fx: E-mil ddress: b.j.hlkon@lboro.c.uk Published by Elsevier Ltd. This is n open ccess rticle under the CC BY-NC-ND license ( Selection nd peer-review under responsibility of the Centre for Sports Engineering Reserch, Sheffield Hllm University doi: /j.proeng

3 Benjmin Hlkon et l. / Procedi Engineering 72 ( 2014 ) Introduction Elite-level bsketbll hs evolved in recent decdes in prticulr in terms of its physiclity nd of the specilistion nd fitness level of plyers. Comprison with plyers from the 1980 s will show increses in verge height nd mss which, when combined with greter physiclity in gmeply, results in methods of mitigting impct-relted injuries becoming more pertinent considertion. The officil bsketbll rules (FIBA, 2012) s pproved by the Centrl Bord of the interntionl governing body, FIBA, stte tht: A foul is n infrction of the rules concerning illegl personl contct with n opponent. Although bsketbll is therefore intended to be plyed in non-contct mnner, mny ccidentl impcts occur nd it is widely regrded mong plyers s contct sport. A longitudinl study conducted by Dick et l. (2007) investigted the injury incidence mongst collegite bsketbll plyers over 16 yer period. It ws noted tht the overll rte of injury occurrence during gmeply ws 9.9 per 1000 thlete exposures which would suggest tht plyers would suffer pproximtely one injury per seson. Of those injuries, 76.6% were directly ttributed to contct, just over two thirds of which occurred s result of contct with other plyers. While injuries not (directly) relted to contct, such s sprins nd strins, were the most frequent, contusions ccounted for significnt proportion of in-gme injuries ( 10%). While, in the study presented by Dick et l. (2007), contusion injuries were not significnt in terms of 10+ Dys of Activity Time Loss, n indiction of the potentil impct of such injuries is provided by Diz et l. (2003) who used imging techniques to investigte the severity of qudriceps muscle contusions in thletes. A specific cse report considered blunt trum experienced to the nterior thigh from knee impct in bsketbll gme ply. The rnge of motion t the knee decresed by nerly 115% nd the thlete suffered severe pin for the three dys following the impct. Subsequent MRI scns reveled tht it took up to 3.5 months for the thlete to fully recover, lthough he ws ble to resume ply fter three weeks. The shift in the physiques of bsketbll plyers nd the incresed physicl nture of the sport hve elevted the prevlence nd severity of in-gme injuries with mny plyers now opting to wer some form of personl protective equipment. Typiclly set of protective undergrments, such s those shown in Fig. 1, re used: compression pdded shorts (Fig. 1) provide protection to the nterior nd lterl thigh, the hip nd the tilbone while compression vest (Fig. 1b) provides protection to both the rib cge nd the thorcic spine. The incresed vilbility nd uptke of such equipment hs prompted the need to better understnd the intensities of in-gme impcts nd usge scenrios to inform improved design nd to understnd its effectiveness. The im of this study ws, therefore, to experimentlly investigte the kinemtics nd kinetics involved in common bsketbll impct scenrios with view to providing better understnding of the potentil injury inducing phenomen experienced. b Fig. 1. Exmple () compression pdded shorts; (b) compression vest commonly worn in elite bsketbll.

4 216 Benjmin Hlkon et l. / Procedi Engineering 72 ( 2014 ) Methods 2.1. Test protocols & prticipnts Investigting the effect of humn-on-humn impcts experienced in bsketbll gme ply presents mny logisticl nd ethicl chllenges. Even stged sports impcts in the lbortory environment (Hlkon et l., 2012), due to the dynmic nd reltively uncontrolled nture of the impcts, inevitbly result in low experimentl control, poor externl vlidity or both. In order to overcome mny of these limittions, three-phsed protocol ws proposed: Humn-on-Bg Impcts: the first phse involved five plyers, with plying experience t Ntionl Legue or better level, performing series of bsketbll-relevnt impcts on freely suspended trining bg instrumented s described in the following subsection. Age, mss nd height sttistics were 23.4 (2.9) yers, 83.6 (12.4) kg nd (8.6) cm, respectively. Prticipnts were sked to perform mnoeuvres involving contct typicl of those experienced or performed in prctice or gme scenrios. The kinemtics nd kinetics of the impct were recorded to provide n indiction of the mgnitudes experienced in bsketbll gme ply. Artificil Impctor-on-Bg Impcts: the second phse involved impcting the sme instrumented bg used in the previous phse with freely suspended rtificil impctor. The dvntge of the rtificil impctor is tht it provides controlled, repetble striking object tht cn be djusted in terms of its mss, geometry nd impct velocity to mtch both the contct res nd pressures experienced in the humn-on-bg impcts. An itertive process presented the opportunity to determine suitble rtificil surrogte to be used in the third phse. Artificil Impctor-on-Humn Impcts: this phse of testing involved impcting nine bsketbll plyers (20.9 (2) yers, 88 (12.8) kg, (6.8) cm), instrumented with pressure sensors fitted between the personl protective equipment nd the body, using the rtificil impctor developed in the second phse t incresing impct intensities up to mximum level equivlent to tht observed in the first phse. This finl pproch yields more controllble method of pplying the impcts t specific impct energies while ensuring tht the prticipnt does not experience extreme discomfort or ctstrophic injurious impct which my occur in less controllble humn-on-humn impcts. By dopting this incresing intensity pproch, llowing the prticipnt to withdrw t ny time, strict ethicl guidelines re dhered to nd level of externl vlidity is mintined Instrumenttion nd other equipment Pressure mpping, kinemtic motion nd high-speed video dt cpture were used to chrcterise the impct events. b c Fig. 2. () 3001E F-Scn sensors; (b) lbortory lyout; (c) schemtic section view of trining bg construction from top.

5 Benjmin Hlkon et l. / Procedi Engineering 72 ( 2014 ) Pressure mpping: Tekscn F-Scn VersTek system with 3001E Sport sensors, s shown in Fig. 2, with pressure rnge kp (0-75 psi) ws selected for this study bsed on its vilbility, low reltive sensor cost nd for resons of obtining dt comprble with those obtined in previous study (Hlkon et l., 2012). Despite its intended ppliction being tht of qusi-sttic nd lower-rte dynmic in-sole pressure mesurements (e.g. git nlysis) the 750 Hz smple rte mkes for resonble number of dt points during the circ 200 ms impct event. The reltively dense (3.9 cm -2 ) sensing element spcing (on sensor ctive re of 107 x 305 mm; 954 elements in totl) enbles resolution of pressure vrition cross the impct region tht is required to understnd contusion occurrence mechnisms. The 0.15 mm sensor thickness, importntly, reduces the invsiveness on the prticipnt in the humn testing. Kinemtic motion dt cpture: to determine the impctor velocity t impct, Chrnwood Dynmics 4x Codmotion cx1 system smpling t 800 Hz ws employed, s cn be seen in Fig. 2b. Active, infrred emitting mrkers were ttched in clusters to the impctor bodies enbling, if required, 3 trnsltionl nd 3 rottionl degrees of freedom of motion to be determined. High-speed video dt cpture: Photron Fstcm 675K-C1 cmer ws used to cpture video dt t between 500 Hz nd 2 khz depending up the impct type (i.e. humn-on-bg, impctor-on-bg or impctor-on-humn) nd the nominl impct velocity. These dt were lso used to determine impct velocity in the bsence of (relible) Codmotion dt. Video frme clibrtion for digitistion (Imge Pro Anlyser) ws chieved by selecting n object of known length in the plne of the impct motion. As shown in Fig. 2b, 40 kg trining bg with n dditionl 20 kg of snd ws suspended from n A-frme. The suspension rrngement ws specified in order tht prticipnts nd the impctor could be redily brought into contct with the bg during the first nd second phses, respectively. The mss of the bg ws determined using nthropometric scling prmeters defined by Winter (1990) for 100 kg individul; the hed, neck nd torso were included. The bg construction, s shown in Fig. 2c, includes 50 mm thick polyethylene chip fom section surrounding the snd core. The resulting bg complince is intended to represent tht of humn soft tissue. In the second phse the impctor ws lso suspended from the A-frme in order tht the impct velocity, trjectory nd loction could be crefully controlled. In the third phse, the bg ws replced with the prticipnt(s). 3. Results Exmple impcts nd pressure dt for the humn-on-bg tests re shown in Fig. 3 in which it cn be seen tht the impct region is typiclly not continuous region of sensed pressure. Furthermore, due to its in-plne stiffness, the sensor hs tendency to crinkle when the sensor/surfce is subjected to reltively smll dimeter impct. b c d Fig. 3. Exmple () elbow impct nd (b) corresponding pressure dt; (c) knee impct nd (d) corresponding pressure dt.

6 218 Benjmin Hlkon et l. / Procedi Engineering 72 ( 2014 ) b Fig. 4. () Artificil impctor used in second nd third testing phses; (b) third testing phse experimentl set-up b Fig. 5. Combined velocities for () elbow impcts nd (b) knee impcts In order to replicte the pressure mesurements obtined during the humn-on-bg phse, n impctor with rdii of curvture of 12.5 mm (Wdi et l., 2007) nd 37.5 mm (Osterhoff et l., 2011), s shown in Fig. 4, ws developed. The impctor ws suspended using light inextensible strings nd relesed from number of drop heights necessry to chieve 1-5 m/s impct velocity with 1 m/s resolution. The nominl contct durtion observed with the impctor ws significntly shorter thn tht observed during the humn-on-bg impct (circ 50 vs. 200 ms) owing to the rigid nture of the impctor vs. the complint nture of the humn body. For the sme reson, the required force levels were chieved with reltively low mss: 2 kg for the elbow impct generted nett force of 318 (7) N t 5 m/s impct velocity nd 2.8 kg for the knee impct generted force of 1044 (74) N t 4 m/s. During the impctor-on-humn testing, s shown in Fig. 4b, impct velocities of 2-5 m/s with 1 m/s resolution were rrnged. Velocity dt chieved re shown in Fig. 5. A single pressure sensor (rther thn pir) per loction ws used in this phse due to the incresed reltive control of the impct loction. Exmple impcts nd corresponding pressure dt re shown in Fig Discussion & Conclusions This study provides good understnding of pproprite msses nd velocities required to simulte gmeply bsketbll impcts. The pressures determined in the impctor-on-humn trils were in generl lower thn those determined in impctor-on-bg impcts which could be explined by the reduced force trnsferred through the

7 Benjmin Hlkon et l. / Procedi Engineering 72 ( 2014 ) b c d Fig. 6. Exmple impctor () elbow impct nd (b) corresponding pressure dt; (c) knee impct nd (d) corresponding pressure dt. personl protective equipment. This is the first time such study hs been undertken nd this represents n importnt step towrds understnding humn response to impcts in sport, specificlly in bsketbll. There re, however, severl res in which improvements could be mde. Firstly, the pressure mesurement system used is being deployed outside of its typicl ppliction envelope nd results must, therefore, be interpreted with cution. A more flexible, less invsive pressure mesurement system with higher sensitivity rnge, ccurte dynmic clibrtion nd miniml sensitivity drift would represent n idel solution. Secondly, the impctor used could hve been mde more bio-fidelic to represent the viscoelstic nture of humn tissue. Vrible stiffness nd dmping should idelly be incorported to tune the impctor for the representtion of different types of humn tissue. The result, of course, would be prolonged contct durtion. The three phsed protocol used in this study provided n importnt mens of fcilitting humn impct testing within ethicl limittions nd provided useful humn response dt. The initil phse of testing investigted humn-on-bg impcts nd provided velocities, contct times, pressure distributions, pek pressures, nd pek forces. The second phse of testing investigted the msses necessry to replicte the humn-on-bg impcts in controlled pendulum impctor system, reduced contct times experienced were ccounted for through the lck of viscoelsticity present in the rtificil impctor. The finl phse of testing investigted the humn response when subject to representtive rtificil impctor strikes nd provided pressure distributions, pek pressures, contct times, nd pek forces for pdded strike on humn tissue. Acknowledgements The uthors would like to cknowledge the support of Nike, Inc.. References Diz, J.A., Fischer, D.A., Rettig, A.C., Dvis, T.J., Shelbourne, K.D., Severe Qudriceps Muscle Contusions in Athletes: A Report of Three Cses. Americn Journl of Sports Medicine 31, Dick, R., Hertel, J., Agel, J., Grossmn, J., Mrshll, S.W., Descriptive Epidemiology of Collegite Men's Bsketbll Injuries: Ntionl Collegite Athletic Assocition Injury Surveillnce System, through Journl of Athletic Trining 42, Hlkon, B.J., Webster, J.M., Mitchell, S.R., Mientjes, M Development of Test Methodology for the Assessment of Humn Impcts in Sport. 9 th Conference of the Interntionl Sports Engineering Assocition: Engineering of Sport. Procedi Engineering Vol. 34, Officil Bsketbll Rules 2012, Fédértion Interntionle de Bsketbll (FIBA), Oct Osterhoff, G., Löffler, S., Steinke, H., Fej, C., Josten, C., & Hepp, P., Comprtive ntomicl mesurements of osseous structures in the ovine nd humn knee. The Knee, 18, Wdi, F., Kmineni, S., Dhotre, S., Amis, A., Rdiogrphic mesurements of norml elbows: clinicl relevnce to olecrnon frctures. Clinicl Antomy 20, Winter, D.A., Anthropometry in Biomechnics nd Motor Control of Humn Movement; second ed.. John Wiley & Sons Inc