Biomechanics of Baseball Pitching & the Ulnar Collateral Ligament

8/18/2019 Biomechanics of Baseball Pitching & the Ulnar Collateral Ligament

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Project Report

Biomechanics of Baseball Pitching & theUlnar Collateral Ligament

BIOE689GCamilo Pascual04/26/16


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1. IntroductionIn the past, tears to a ma or lea!ue pitcher"s el#o$ ulnar collateral li!ament %&C'( $as consi)ere) a career*en)in!

in ur+, #ut in 19 4, orthope)ic sur!eon -r. ran o#e per orme) the irst &C' reconstruction or 3 omm+ ohn5 sur!er+ on

ma or lea!ue pitcher omm+ ohn, #+ usin! a sur!ical !ra t to replace the &C' in the me)ial el#o$ $ith a ten)on rom

else$here in the #o)+, an) e ten)e) his career )ramaticall+. or people that ollo$ ma or lea!ue #ase#all %7'B(, it

appears that there has recentl+ #een an increase in the num#er o el#o$ li!ament in uries an) &C' reconstruction

proce)ures per orme), as $ell as an increase) a$areness in the mana!ement o a pitcher"s $or loa) in hopes o

pre entin! in ur+. leisi! et al reporte) that -r. ames . :n)re$s operate) on the el#o$s o 184 #ase#all pitchers

#et$een 199; an) 1999, an) the el#o$s o 624 #ase#all pitchers #et$een 2000 an) 2004, $hich in)icates a )ramatic

increase in the num#er o el#o$ sur!eries in these consecuti e ;*+ear perio)s an) sho$s that #ase#all pitchin! in uries

are clearl+ a serious pro#lem ues actin! upon a pitcher"s el#o$, an) the stresses an) strains su# ecte) to the &C' $ere speci icall+

in esti!ate). his research permitte) a more thorou!h un)erstan)in! o the #iomechanics o #ase#all pitchin! alon! $ith

speci ic theories, stu)ies, an) a mo)el, properties o the &C', anal+sis o pro#a#le causes in the rise o 3 omm+ ohn5

sur!eries in #ase#all pitchers, i)enti ication o possi#le pre ention strate!ies that can or are #ein! emplo+e), an)

i)enti ication o potential uture research.

2. Biomechanics of Baseball Pitching

: #ase#all pitch is one o the most )eman)in! acti ities on an athlete"s el#o$. he el#o$ is su# ecte) to #oth lar!e

orces an) tor>ues at certain instances )urin! the pitchin! motion. he #iomechanics o the el#o$ oint is a unction o

inematics, inetics, an) electrom+o!raph+. ?inematic an) temporal parameters )escri#e ho$ somethin! is mo in!, $hile

e clu)in! $hat causes the motion, an) uses re lecti e mar ers place) at certain locations on a pitcher"s #o)+ $ith hi!h

spee) i)eo!raph+ to >uanti + linear an) an!ular )isplacement, elocit+, an) acceleration uations $ith the collecte) i)eo!raphic )ata to

calculate/estimate the net orce an)/or tor>ue actin! on the o# ect uanti ication o

muscle acti it+ usin! sur ace an)/or in)$ellin! electro)es


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he %1( $in)*up phase #e!ins

$hen the pitcher initiates mo ement

an) en)s $hen the ront nee has

reache) its ma imum hei!ht,

t+picall+ lastin! 0.; to 1.0 secon)

rom the stance oot pi ot to $hen

the nee is at its ma imum hei!ht.

he %2( stri)e phase #e!ins $hen

Figure 1. he si phases o #ase#all pitchin!@ $in)*up, stri)e, arm coc in!, arm acceleration, arm)eceleration, an) ollo$*throu!h. Ima!es represent the instances separatin! the phases@ initial motion,#alance point, oot contact, ma imum shoul)er e ternal rotation %7a E (, release, ma imum shoul)er internal rotation %7a I (, an) iel)in! position. ue o ;2 to 6 D m %mean@ 64 D m( is !enerate) #e ore 7E to

resist this al!us tor>ue, an) the le or an) pronator muscle mass o the orearm )ispla+ mo)erate to hi!h acti it+ % Table

1(, $hich also helps contri#ute to this arus tor>ue ue as

a critical instant an) i)enti ie) it as a critical loa) relate) to el#o$ in uries % Figure 4 (


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Figure 2. or>ues applie) onto the orearm at the el#o$ in le ion an) arus)irections. he instants o oot contact % C(, ma imum e ternal rotation %7E (, #allrelease % E'( an) ma imum internal rotation %7I ( are sho$n. ue $as !reater in the ast#all an) cur e#all than in the chan!e*up, an) el#o$ le ion tor>ue $as !reater

in the cur e#all than in the chan!e*up % Table 2 ( ues reporte) or each pitch t+pe $ere

lar!er than $hat $as reporte) in other re erences %


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mar er on the han), $hich monitors $rist inematics an) impro es the location o the han)"s an) #all"s masses an)

sho$s the importance o mar er placement or inematic/ inetic stu)ies. he authors conclu)e), althou!h

there $ere si!ni icant inematic

)i erences #et$een the ast#all

an) cur e#all, the resultant oint

loa)s $ere similar %the el#o$

pro imal orce $as the onl+

si!ni icant inetic )i erence

#et$een the 2 pitches( an) )i) not

in)icate that either pitch $as more

Table 2. oint ?inetics Compare) :mon! Pitch +pes a


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&C', tension in the le or*pronator muscle mass, an) compression in the ra)iocapitellar oint, an) thus the !reater arus

tor>ue !enerate) #+ colle!e an) pro essional pitchers ma+ impl+ that the+ are at a hi!her ris or &C' tear, muscle strain,

an) other arm in uries. he authors conclu)e) that the )i erences, or lac thereo , amon! competition le els in)icates

that pitchers shoul) learn proper mechanics as earl+ as possi#le, an) #uil) stren!th an) itness as the #o)+ matures uires intense muscle acti it+ an), there ore, can #e

consi)ere) to #e per orme) un)er anaero#ic con)itions, #ut the act o pitchin! in a !ame can e pecte) to #e per orme)

un)er aero#ic con)itions an) is a reason $h+ ati!ue is e pecte) to a ect pitchin! #iomechanics. :s muscles ati!ue, their

a#ilit+ to a#sor# ener!+ )ecreases, $hich allo$s or !reater stresses to #e applie) to articulations an) inert structures,

such as the el#o$ oint an) the &C', an) un)er this premise, Escamilla et al stu)ie) the e ects o approachin! muscular

ati!ue on pitchin! #iomechanics )urin! a simulate) #ase#all !ame %1; pitches per innin! or to 9 innin!s(


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#et$een a hi!h elocit+ !roup %those $ho thre$ aster than A8.0 m/s L8; mphM( an) a lo$ elocit+ !roup %those $ho thre$

slo$er than A4.2 m/s L 6.; mphM( uations are %&. '1( to

'$( . he !eneraliKe) orces/tor>ues are calculate) usin! the mo)el* ali) inematics %e perimental )ata collecte)( an)

su# ect"s se!ment parameters % rom 6 pitchers( in %&. '1( , V (θ , θ́ ) an) g (θ ) are the elocit+*)epen)ent tor>ues

an) !ra it+ tor>ues ectors, respecti el+. he an!ular accelerations pro)uce) #+ tor>ues are calculate) usin! %&. '2( an)

'3( , I (θ )− 1

τ inclu)es onl+ the instantaneous e ects rom the muscle orce at that instant, $hile I (θ )− 1

V (θ , θ́ )

re lects the cumulati e e ects rom all histor+ o all muscles an) !ra it+ tor>ues until that instant. he elocit+*)epen)ent

tor>ue can #e e presse) as the sum o se eral inematic aria#les L %&. '4( an) '$( M. he accelerations $ere inte!rate)

rom N200 to 0 ms or the shoul)er, el#o$, an) $rist, an) rom N200 ms to the time o pea elocit+ or the trun . he

results o this stu)+ are some$hat similar $ith pre ious re erences %ue o A2 D m are calculate)/reporte) % arus* al!us tor>ue is not6 o 10


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inclu)e) in this mo)el( < =. he main conclusion/similarit+ is the in)ication that #ase#all pitchers accelerate the )istal el#o$

an) $rist oint rotations #+ utiliKin! the elocit+*)epen)ent tor>ue that ori!inate rom the pro imal trun an) shoul)er oint

tor>ues in the earl+ phase o the pitchin! motion, an) pro i)es stron! supportin! e i)ence o the inetic chain principle

ue. he lo$er part in)icates the cumulati e e ect pro)uce) #+ theelocit+*)epen)ent tor>ue. he !ra it+ tor>ue is not sho$n here. he soli)

line in)icates the )irect e ect rom its o$n tor>ue. he )otte) %or li!hter(line in)icates the remote e ect rom the other tor>ues. %a)apte) rom < =(

Inverse Dynamics

τ = I (θ )θ́− V (θ , θ́ )− g (θ ) '1(Induced Acceleration Analysis

´θ= I (θ )− 1 (τ + V (θ , ´θ )+ g (θ )) '2(

θ́ j= ∑i= 1

13

A ji τ i + ∑i= 1

13

A ji V i + ∑i= 1

13

A ji gi

¿ (θ́ jτ 1 + θ́ jτ 2 + …+ θ́ jτ 13 )+ θ́ jV + θ́ jg'3(

Decompostion of the Velocity-Dependent Torque

V (θ , θ́ )= ∑i= 0

3

{V Ai ( Ai)+ V Bi (Bi)+ V B gi (Bgi )+ V C i (C i)} '4(

Ai= Ω i × (θ́ i)

B i= ω i × (ω i × L i)

Bgi= ω i × (ω i × L gi)

C i = ω i × ( I i ω i)

'$(

4. )lnar *ollateral +igamenthe &C' is compose) o three #un)les@ an anterior #un)le, a posterior #un)le, an) a trans erse li!ament % Figure , (

o t tissue restraints, such as the &C', pro i)e primar+ static an) )+namic sta#ilit+ rom 20H to 120H o el#o$ le ion,

$hich is the arc o motion $here #ase#all pitchin! occurs. he anterior #un)le is the primar+ restraint to al!us orce o

the el#o$ rom A0H to 120H o le ion an) ma+ #e consi)ere) the 3 e+5 to the sta#ilit+

o the thro$in! el#o$, the posterior #un)le applies more sta#ilit+ a!ainst al!us

stress $hen the el#o$ is le e) rather than e ten)e), an) the trans erse li!ament

has no contri#ution to the oint"s sta#ilit+ ser in! onl+ a support unction


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anterior #un)le is su# ecte) to near* ailure tensile stresses )urin! the arm coc in! an) arm acceleration phases, ha in! a

ma imum el#o$ arus tor>ue o 64 D m, a ma imum el#o$ le ion tor>ue o 40 to 60 D m, an) a ma imum el#o$

an!ular elocit+ o 2,100H to 2, 00H per secon)


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$(, or sti ness %Table , ( #et$een an+ o the ten)on !ra ts stu)ie).

Each o the ten)on !ra t reconstructions teste) $ere si!ni icantl+

$ea er an) less sti than the intact or nati e &C'. he authors

conclu)e) that there $as no #iomechanical a) anta!e !aine) usin!

a lar!er ten)on !ra t instea) o a palmaris lon!us !ra t an) the most

rea)il+ a aila#le !ra t source $ith lo$est mor#i)it+, $hich is o ten the

palmaris lon!us ten)on, shoul) #e use) or &C' reconstruction ue o

28 D m an) 48 D m or +outh an) hi!h school le el pitchers, respecti el+, $hich

he current pre ention strate!ies #ein! emplo+e) inclu)e

Other possi#le pre ention strate!ies

inetic chain principle

,. *onclusions " Future Research

9 o 10


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his research paper outline) the #iomechanics o #ase#all pitchin! an) is )i i)e) into si phases. he ma imum

el#o$ arus tor>ue o 64 D m is !enerate) ust prior to 7E , )urin! the arm coc in! phase or A r) phase, an) is re!ar)e)

as the critical instant relate) to el#o$ in uries alon! $ith the repetiti e trauma that lea)s to tears or ailure o the anterior

#an) o the &C'.

Base#all pitchers $ith &C' tears most li el+ re>uire &C' reconstruction sur!er+ to return to the !ame an) must

un)er!o a len!th+ reha#ilitation a ter the sur!er+ to allo$ the ten)on use) to replace their torn &C' to con ert to a

li!ament an) o#tain the necessar+ #iomechanical properties.

he ollo$in! are potential uture research topics to urther our un)erstan)in! o the #iomechanics o #ase#all

pitchin! an) the cause o &C' tears@ %1( ati!ue stu)ies )urin! an actual !ame to )etermine ho$ e treme muscular ati!ue

a ects pitchers" inematics an) inetics, %2( e pansion o inetic chain mo)el #+ Jirashima et al $ith more )e!rees o

ree)om or the el#o$ oint to inclu)e the calculation o el#o$ arus/ al!us tor>ue, an) %A( !eneration o !ra ts that

resem#le the #iomechanical properties o nati e &C' to re)uce the current len!th+ reha#ilitation re>uire). :lthou!h

outsi)e the scope o this class, epi)emiolo!ical stu)ies ma+ also help i)enti + other causes or the current rise in &C'

tears or in uries %i.e. pitchers $ho pla+e) in $arm*$eather climates ha e un)er!one &C' reconstruction more re>uentl+

an) earlier in their 7'B careers than pitchers $ho pla+e) in col)*$eather areas(. he $eara#le technolo!+ that $as

recentl+ appro e), 7otus Base#all lee e %measures stress on el#o$( an) Qeph+r Bioharness %monitors heart an)

#reathin! rates(, $ill pro i)e 7'B teams $ith more personaliKe) )ata a#out their pla+ers, an) there is a potential or the

intro)uction o ne$ en!ineere) technolo!+ to monitor/measure other inematic/ inetic aria#les an) ati!ue state, $hich

ma+ hope ull+ help to pre ent or re)uce in ur+ an) &C' reconstruction sur!eries in #ase#all pitchers.

0. Reference -rticles


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Biomechanics of Baseball Pitching & the Ulnar Collateral Ligament