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Biomechanics of Muscle: WITH PARTICULAR APPLICATION TO
STUDIES OF GAIT
HERBERT ELFTMAN
J Bone Joint Surg Am. 1966;48:363-377.
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The Journal of Bone and Joint Surgery
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O*I4,
Biomechanics
WITH
PARTICULAR
BY
An
human
r1ime
mmmovemmment
with
Course
comitrolled
arc
ELFTMAN,
Lecture,
is built
body
a quarter
APPLICATION
HERBERT
Instructional
nmuscies.
striate
TO
PH.D.*,
The
aroumid
by
billion
of Muscle
NEW
American
For
this
OF
YORK,
Academy
a cOlflplex
mmmuscle fibers
STUDIES
GAIT
N.
of Orthopaedic
of bomic levers
purpose
artfully
Y.
each
Surgeons
whose
posit-iomm
immdividual
assemmmbled
amid
is provided
immf-o mmiuscles
ammo! at-
to the
skeletal
levers iii strategic
positions.
Motion
is coorditmated
through
the
nervous
system,
which
can devise
progranis
for commiplicafed
activities,
store timenmi for
later
use, arid modulate
f-heir performmmamice under
the immfluemmcc of feedback
signals.
facimed
l)reselifaf-iomm
This
than
lurloscs
factors
fessiommal
sidered
of the
amid those
first
bionmechammics
of mmmuscle will
enml)hasize
sonic
of these
of-hers.
No f-reatmmment of Iimuscle biomecimammics
adequate
can ever be sinmple, but if the I)ropert-ies
of single
fibers
mmmore
of nervous
coordimiation
last,
for
are
sommme of time difficulties
procon-
will
be
mmminimmiized.
Intrinsic
Ami average
imummman
met-er
imi diammieter.
20,000
discs
quently
fiber
are
400
times
the
at rest
secfiomms
mmmost readily
size
of the
Muscle
is five
Z nmembramies
sommmefimmmes called
iii describing
cami be visualized
about.
of Single
fiber
nmuscle
Trammsverse
that
used
Properties
Fibers
ceimtinmcters
divide
the
sarcomeres,
!ommg and
fiber
although
.05
that
tcrmmi
is mmmorc fre-
of fibrils
rather
thami fibers.
Time structure
i)y means
of a nmodel. The Ummited States
average
human
muscle
disc
mmmilli-
immto approximmmately
ammo! has
of time
olinme is
simmmilar propor-
tiomis. Timus a simmglc nmuscle fiber cami be rcprescmmted
by a stack of 20,000
dimes,
which
would
mmmake a colummmmi over sixty feet high.
Each
disc comif-aimms about
three
mmmilliomi
filaments
of myosimm, ommly omme of which
is showmi imi Figure
1. Parallel
to the nmyosimi
are
filaimmemmts
of actimm,
amicimored
to
time Z nmcmbrammc.
Nervous
excitation
causes
mmmyosimi amid
actin
to develop
f-he mmmutual
attraction
f-hat
is the
source
of nmuscle
temi-
siomm.
The
Length-Tension
Iii many
Curve
ways
fact
that
This
l)lmenmonmenOli
time immost inmporf-ammt
if-s potemmtial
femmsiomi
was
first-
siimgle
depemids
mmmeasurcd
on
by
characteristic
its
Blix
length
4,5,6,
of f-he mmmuscle fiber
at
a
the
Swedish
mmmommmenmtof
is the
excitatiomm.
physiologist,
in 1891.
The contribution
22,26 is illustrated
by
drawn
l)erpemmdicular
time
leimgth-tensiomi
with
time nmyosin
area
of
interactiomm
Omi time other
of-her
of
the
*
York,
VOL.
of actin
amid myosin
to the lcmmgth-temisioni
relationship
19,2o,2m,
the graph
imi Figure
1. This
graph
is so desigmmed
that
a limme
frommm the end of the right-hand
actin
filanmemmt will intersect
curve
at f-lie al)propriate
point-.
If the sarcomcrc
is stref-ched,
stayimmg iii l)ositiomm,
the actin
filamemit
will sliole further
out, its
the myosin
will decrease,
if time fiber shortemis,
the two
with
hand,
amid when
they overlap
mmmyosin encoumitered
they
after
l)epartnmemit
College
of Amiatonmy,
will hot-h
timey pass
of Physiciamis
amid the tension
will olinmimmish.
act-in filammmemmts slide toward
each
be affect-ed
by the reversed
polarization
the mmmidolle mieutral
segmmmeimf. Owimig
and
Surgeomms,
Columbia
University,
to
New
N. Y. 10032.
48-A,
NO.
2, MARCH
1966
363
364
A.A.O.S.
this
relatioumsimip
Flme
ramige.
rest
15101
iP1
at
LECTURE
factors,
time t-emmsiomi o!ecreases
its time fiber’ slmortemms in this
f-lie t-emision is greatest
is calleol,
sommmewhat arbitrarily,
which
rFhme first
mimay be
comimmect-ive
teImsiOli
iim (hfleremmt
f-issue,
ijicance
ummi-il it
mmiuscle
Figure
in
single
fiber
zero
niuscies
Tens
the
\Viiich
give
total
time
ion
fiber
wimemm
f-he fiber
f-lint )ass
over
other
fact-or
fascia,
which
tensiomm
o!evelops
curve
frommm
are
clue
is time uresemmce
commtributes
for
to
of sarcommmeres
of
passive
it mimust
be
aolded
time mmiuscle.
ip
cami l)rOdU(’e
(!ecmetmses
is a)proxinma1-ely
only
differemit
differemmces
of lommg chains
Time
teimsiomi
Relations/i
nmuscle
sommiewimat
These
consists
commmmective-tissue
to
are
2-A.
of comitm’acf-iomm.
After
of the Length-
reason,
eIicim
states
tensiomi
femmsiomm
becommies
imm time whole
simowmi
immcluo!immg sam(olemmmmmma amid
acf-ommmyosimm
‘fime
timis
is that
mvlmeii stref-cimeol.
time
if/fl
iommshi is
ammo! are
sarcommmere
factors.
wimich
ii i’elat
m-lemmgf
mm time
two
S
ama! of-her
lemmgt-h
COURSE
letigtii.
those
to
IXSTItUCTr0NAL
omme joint
-1.0
nmust
as
time
fiber
simorteims,
60 ler
cent
of rest
lengtim.
For
have
fii)ers
nearly
timree
timmies
R
2
0
-0.5
U)
z
Ui
I-
LENGTH
-
ACT
N
________________________________________
_\
-Ic
-‘
-‘
:;
-\
r
r
:
r
z
z
z
Fmu.
1
Part of omme sar(’ommiere
simowim at restlemmgth.
The
di.stamice
betweemi
the menmbranes
(Z) is 2.2
micra.
Whemi time mmmyosimmfilanmeimt
is fixed imi position,
shortenimig
timid lemmgtiiemmimig occur
bysymnmetrical slidimmg of time mictimm filaments
with
respect
to the nmyosimm. The
chamige
iii tension
associated
with
length
(‘lmammges (‘liii be followed
omm time iemigth-temisiomi
diagrani
iy observimig
the Positiomi
of the
dotted
limme as it mmamves to the right or left with time actimi. It desigmiates
rest lemmgth.
as lotmg as time distance
This
joimit-.
timrouglm
k’mmgtim allomvs
and still retaiim some
relat-iolmsimul)
i)etweemr
sioleratiomi
in evaluating
force
fiber
wimiclm they
themmm to exert
whemm
short-eu
(ltmrimmg commil)lete
mmmaximmmtmnmforce
mmmovemmmemmt
of time
wimemm t-imey immitiate
mimovemiment
time mimaximmmummi mmmovemmmemmtis conmpleted.
Timis
close
lemmgt-ii ammo! ahmml)lit-ude of shomtemmimmg is aIm immiporf-ammt contime ProsPective
efficacy
of a sui)stit-tmt-e
immuscle after
tenolon
trammsfer.
Iii t.mvo-joiumt nmuscles,
of
extemmsom’s are classic
examples,
conimimoolat-e
timemmmselves commiplef-ely
mmiaxinmummm mmmovemmmemmt ili
ftmllv
joimmts
decreasing
kimec
shown
which
time imammistrings
f-he fiber lemmgf-h is too
extemioleo!
(droppimig
is commmpletely
in Figure
uies
to time cimange
associated
the
joints.
hanmst-rimmgs
dowmm time lemmgt-h-tension
flexed.
2-A.
f-lie
The
Time
opposite
muscles
are
commdition,
ami(l time (ligital
flexors
ammo!
simort for the mimuscies to ac-
immlemigtim ivimicim would
accommmpamiy
If a persomm stammdimmg with
his hip
to flex
one
curve
kmmee, he will
ummt-il it reaches
tlmemm in a state
passive
TIlE
of active
immsufficiemmcy,
JOURNAL
OF
BONE
feel
the
zero)
temmsiomm
before
the
immsufficiency,
cami he illustrated
ANI)
JOINT
SURGERY
as
HERBERT
by keeping
conditions
the kmiee
stretchimmg
insufficieimcy
of
inmsufficiermcy
the
extend
the
of Speed
Time
imm whicim
stimulated
produce
or
change
being
used
those
active
of
the
the
nmuscle
has
as
iii
result
time
either
so
physiology
lemmgtim clmammges,
is rarely
require
which
temisiomis
all
fotmmic! outsio!c
with
of
time
fimmgers
to
; fiexiomm of
states
Isommmef-ric
simmce
f-he
beemi
illustrated
lemmgfim at
contractiomi,
active
the
have
f-lie
by
whicim
it
was
slowly.
Muscles
mmiust frequemitly
aim exferhmal
load.
Such
activity
laboratory,
iim which
vary
far
mmiaimmtaimmed
immsimortemmimmg.
commtractiomi,
ext-emmsor
wrist
is extendeol
these
joimits.
Produced
commsidered
mmommiemmclature for
that
Isotommic
365
MUSCLE
conimoim
when
the
it to govern
immlemmgfh is kmmowmi as ami isommiet-ric
stat-es
life
on Tension
relatiommships
in modermm
stability.
OF
has
changed
lemigth
extremimely
emiough
temmsioim to coummterbalance
just
without
immability
of Contraction
lemmgth-temmsion
situations
normal
the
is
immterphalammgeal
joimits completely
lenmgthemms f-he mmmuscle amid enables
wrist
Effect
BIOMECHANICS
fully extemmded
amid then
attemptimmg
hip flexiomm ; ummo!er timese
of the comimmective-tissue
elements
will bring
about
passive
the hip joint reaches
its limit of mimoveimmemit. A gooo! example
before
lommg
active
ELFTMAN:
contraction
muscles
t-emmsion
of just
is as commmmomm hi
are
remimains
laboratory,
time immStantammeous
time t.ermim contraction
of mmmuscle inst-eaol
so
imimport-ammt
commstamit
for
while
simmce miatural
f-he
mmmovememmts
load.
I
U
I
z
I
Li
I
U
I
I
-LO
z
U)
0
z
U)
z
Li
Li
-Q5>
U
4
L
.6
.8
.6
LENGTH
CONTRACTION
ISOMETRIC
j
CONTRACTION
FIG.
2-B
2-A:
Lemigth-temisiomm
diagram
for isometric
contractiomm
of a muscle
fiber.
The
differemices
this diagram
amid Fig.
1 are dime to the arrangememit
of sarcomeres
in series
immthe fiber amid
of passive
stretch
of commnective-tissue
elements,
CT.,
which
add to the active
temmsiomm of
betweemm
effect
actonmyosimi,
M.
Fig.
2-B:
Length-tensiomm
diagranm
metric
values
for comparison.
When
veloped
is greater
than
the isometric
the tensiomm is less than
isometric
to
the
The
Figure
general
2-B.
duction
effect
The
wit-h
speed
will
depemmdimmg
while
tO
.8
LENGTH
2-A
FIG.
Fig.
1.0
of speed
isometric
immfinmitcly
always
it is active
slow
simeed.
of contractioim
curve,
produce
the
on
for fast- comitractiomi
(solid
limme). The
dotted
limie shows
isoa muscle
is stimulated
amid themm stretched,
the temisiomm dotension;
whereas
when
the muscle
shortemis
after
stinmulatiomi,
a degree
that
depends
on the speed
of simortemmimig.
chammge
less
Iii
will increase
drawn
as
of length.
f-haim
on
tension,
fashiomi,
its t-emmsionm, sometimes
l)roo!Imctiomm
is
simowim
iii
limme, represents
A nmusclc
isometric
a commmplemmmentary
teimsiomi
a dotted
fiber
temmsiomm prosimortenimig
at a fimmite
time anmounfstret-ciming
sufficiemitly
of
o!ecreasc
time mmmuscle rapidly
to rupture
muscle
or
tendomm.
Work
Done
Physical
VOL.
48-A,
NO.
by Muscle
work
2, MARCH
and
on Muscle
is defimmeol as
1966
time l)rOdUct
of force
timmmes time distaimce
timrougim
366
A.A.O.S.
INSTRUCTIONAL
COURSE
LECTURE
L
PASSIVE
-.
MAXIMUM
STRETCH
WORK
ACTIVE
a
ISOTONIC
Fmu. 3-A
Fa;.
STRETCH
SHORTENING
Fmu.
3-B
3-C
Fig.
3-A:
Time work
done
by a niuscie
imi three
experimmmemmts
imm which
time muscle
was passively
st ret(’iie(l
tmmi(1 t hemi stimmimilated
to a. givemm temmsiomm, with
slmi)sequemmt
isot-omiic
simortemmimig.
Time work
(lomme is (‘qual
tii tue
shaded
area
imi eacim experinmemmt
simice time work
domme is the product
of force
t immies cliamige
of lemmgth.
Fig.
3-B: \laximimumim
work
of which
the nmiiscle
is capai)le
is attaimied
by passive
stretch,
stimulat iomm, timid t imemi decrease
imi temmsiomm as the
nmuscle
shortemi.s.
Fig.
3-C:
A miiimscle fiber
remmmovimmg emiergy
from
the bod’
as it is actively
stretCiie(I
amid subse(m(iemitlY slu)rtemiecl;
the dotted
area
measures
the excess
of energy
received
during
stretchimmg
over
amid tii)Ove
time work
domie iii shortemiimig
immdicated
by the lined
area.
it- mmmoves. Althougim
mviiich
reoluires
time
oloes
imot
wom’k,
t-imem’e is
vork
o!Omme
Oh
omm its
till’
o!egradat-iomm
olescetiol
iim(
mntmscle.
Pi1551V(lY
fronm
au isonmetric
of
mmmove. Likewise,
siimce
it- does
exl)emmdifure
nmetabolic
am unloao!ed
mmmoveimmemmtbut
at-f-acimnmemmt-s.
mmmuscle.
This
to heat,
is invaluable
imeigimt-s
by
3-A
st-retcimed
comivertimmg
diagram
lemigt-im-temisiomi
ligume
trammsfer
simovs
three
commtm’action
energy,
nmuscle
mmoforce.
When
Potemmtial
or
ba-c!
the
booly
imm each
o!oimmg
teimsiomm shorterms,
stretches
a muscle,
usually
work
is
by
its
folloveol
to slow
its nmovemmmemmt ammo! to
cami be dissipated.
of the vork
olonme by amid on
of wimich
time mmmuscle was first
to heat
visualizatiomi
comit-racfiomms,
exerted
lemmgtimemms without
to time mimuscie,
emmergy
fummct-iomi amid
simmce time force
a nmtmscle exerting
atm external
in allowimig
imo work
simortemms
When
of emmergy
allows
iem’fom’mmis a useful
it does
which
to nmaximmiummi lemmgt-h amid timemi stimulated
to aim active
TENDON
temmsion
OF
ORIGIN
MUSCLE
FIBERS
TENDON
OF
JOINT
AXIS
.-.-----
?5
-15
.05
Flu.
4-A
FIG.
4-B
Fig. 4-A: Time lemmgtim of a muscle
fiber capai)le
of producimig
180 degrees
of flexiorm while
shortening
40 l)0 (‘emit- of its rest lemmgth is short-e.st
whemi time muscle
imiserts
near
the joimit. Whemi
the distanmce
fromim time joimit axis to the poimmt of imisertiomi
omm the simort i)omme segmemit
is more
thami 0.25 times
the
lommger bone
segmimemmt, complete
flexiomm is mmot possible.
Fig.
4-B:
Typical
niimscle
comistructiomi
with
short
fibers
attached
to temidons
of origin
amid insertiomi.
The limme of aetiomm of the muscle
amid its lever
arnm with
respect
to the joimit axis are showmi.
THE
JOURNAL
OF
BONE
AND
JOINT
SURGERY
HERBERT
equal
to a suspemided
the amouhmt
contractiomms
weight
showhi by
is measured
:
ELFTMAN
the
that
was
BIOMECHANICS
then
lifted
as the nmuscle
obtained
mmiaxinmumim
amount
by
commtract-ion
isotoimic
imi Figure
3-B.
stimulated
to
f-he
achieved,
although
wimat
lined
areas.
area.
The
Here
of
simice
f-he
line amid the base
at an imiternmediafe
which
Obviously,
nmay
isotommically
hue. It is obvious
temmsion f-imammat
1mm f-he shorfenmimig
area
that
is thus
to
Immany
to
together
iii
a
fibers
mmmuscle
(wide
black
bamids),
immg to 60 per
each
capable
creases
as the 1)Oimmt of fiber
joimmt axis,
umit-il f-he longest
of time short
lemmgth
their
will imot be bug
a
chamice
niatter
of
f-hat-
lost-
exanml)le
froimm time body.
(rest-)
of
fibers
capacities
shows
fibers.
the
fiber
product-ion
these
unit-ed
of fleximig
forces
must
to
be
the
large
gaf-here!
fummcf-iomial
re-
omie of the limmmif-ations imimposed
Three
mmmuscle fibers are showmi
joimit
through
lemmgth.
The
180
degrees
by
lemmgfh of fiber
siiortemm-
needed
iii-
atf-achmmmcmmt- to f-he distal
bomme mmmoves fart-imer frommi time
fiber simowmm stretches
fronm origilm to imiserf-iomm. If time
bomme lever
nmmuscle fiber
actually
is a general
emmergy
the
body,
1’igure
4-A
of muscle
of ifs greatest
cent
iii
human
adapt-s
(iuireniemmts
of f-he joimifed skeletomm.
by f-he lemigtim-temmsiomm characteristics
physical
cooperate
of the
which
fashiomm
it-s tensioim
be
The arrows
immdicate timat time
to the sumim of time dotted
ammo!
did work eoiimal to f-he limmed
muscle
total
3-C
be
length,
of Muscles
nmust
f-he joints
commfrol
with
canmiot
Figure
mmever
with
mmmaximmiunm lemmgth,
slowly
specificatiomis
f-he
f-he
cami
vary
to
shorten
approached.
followed,
equal
capable
tensiomi
stretched
to
these
be closely
is
the
when
emmergy is to be dissipated.
stretched,
acceptimig
energy
equal
imappemm
actively
Simmce
that
allowed
Structure
emiough
a nmuscle
it requires
mmmuscle is passively
curve.
they
dotted
work
f-emmsiomm, amid
isonmetric
nmay
mmmuscle was
of
isonmef-ric
followihmg
of
short-cued
exf-remmme.
The
as
367
MUSCLE
horizoimtal
arrows.
Simmce f-he work done by each of these
by the product
of force and shortemming,
time work domme will
be equal
to f-he area betweemi
the force-excursion
that for isotonic
commtract-iomms more work is done
either
OF
is mimore fhamm omme-fourth
emmough
to produce
a full
mimost- hunmmaim muscles
are
that
of time bug
180 degrees
arranged
omie, time
of flexiomm. It is not
alniost
parallel
to time
bommes.
The
nummmher of mmmuscle fibers
required
in each
nmuscle
to give
it sufficient
stremigtim
is so large
that- packimig
problenis
arise.
Simice f-lie mmmuscle fibers
or fiber
bundles
must
be arranged
parallel
for f-heir immdividual
forces
to sunmmaf-e,
a (Oilveniemit
packing
fibers
are
shapes
syst-enum
attached,
consistent
force
Figure
the
Whemi
.
arraimgemmmemmf
pennate
in
with
developed
fiber
is a temmoiomm of origimi
as
4-B.
space
curved
gives
of Capacity
of Muscle
Imi est-immiat-imig the
remmmenmbereo!
of the
fiber
which
it
roughly
f-imat- time
for
fummctiommal
dist-ammce
capacity
olepenmds
are
nonmemiclature
to
f-he
total
to which
be
time
wrapped
greatly
cut
of
cross
sectiomi.
now
of all the
force,
nmaxinmunm
or
fifty
isometric
l)011mm015
muscles
NO.
2,
MARCH
in
time
1966
ler
iii
force
square
imummmami
body
and
into
frohmm
time
dissection,
iii
bipennate
time
ammo! itmulti-
Work
of f-he nmuscle
f-lie
sect-ion
in Figure
nmuscle
Simice
nmyosin
of all
of
4-B,
camm shorten
nmuscle.
imumimber of
cross
fimose
of immuscle
the
Production
which
the
on
ficiemmt
48-A,
def-racf-immg
surfaces
lemmgt-h, mmot f-he lemmgfh of f-he emit-ire
camm olevelop
proport-iommal
sectiomm,
Force
through
to as f-lie physiological
VOL.
f-hemi
muscles.
Estimation
for
the
to
of insertion
nmay
without
temmdon
rise
a temidomi
temmdomms
available
these
disclosed
and
These
it nmmust- be
is a fracfiomi
time mmmaxinmunm force
filammmemmt-s present-,
time fibers,
usually
is
if.
referreol
Mammy est-inmafes
have beemm made
of time coefbeing
in the mmeighborhooo!
of 3.3 kilograms
use
per
inch.
square
cemmtinieter
Simmce the
is a)proximmmately
total
of
physiological
physiological
six square
cmoss
feet,
cross
section
if all were
to
368
A.A.O.S.
contract
simimultaiieously
twemmty-two
such
as
mmmaximmmumim
Fick
proximmmatiomm
three
tabulated
could
times
be
by
his
of the
to
work
fiber
olo .66 kilogram
control
No
that
forces
time
could
Consideratiomi
(Fig.
3-B)
the
a force
of
realized,
authori-
do
by
some
multiplying
of the areas
under
suggest-s
f-hat. a better
ammioumit
overestimimated
of
of
f-he
excellent
is
simortenimmg
the
ap-
by
one-
mmmaximmmummm
temmsiomi by
fables
for
body
kmmee, the
joint
is always
time reference
axis
shifts
as the
poimmt
is ijrovided
Each
of work
under
optimum
Body
work
capacity
in the
about
the
be, there
in more
movement
its
mass,
since
centinmcter
of
circummistances.
body
joints
because
which
they
connect
can
them.
is always
aim axis about
which
complicated
joints,
such
as
progresses
muscle
by
cubic
Segments
effective
segments
for
do
section.
are
a joint may
each
imistant;
at
can
cross
on
produce
the
occurring
muscle
tinmes
of Muscles
comnplicated
mmmovemiient
army
centimeter
muscles
rotation
mmmatter how
was
muscle
otherwise
length
Action
nih
Fick
exert
relationship
each
mmmultiplyimmg
Since
estimates,
esfimmiate
coulol
that
would
by six.
is l)roportiommal
milUscie
work
LECTURE
they
lemmgth-temmsiomm
the
obtaimmed
mimodermm
l)e (livioled
A rough
this
leimgth
optimmmumn
time mmmaximmmummi
t-cmision.
simould
COURSE
by nmaximmmunm
shortening.
diagrahmm for mimaxinmummi work
force
lengt-im-temmsion
half
at
tons.
f-lie imimporf-ammcc of the
Before
ties
INSTRUCTIONAL
but
its
instantaneous
the
the
position
actiomi.
Simice
f-lie human
body
moves
by a series
of rotations
of segments,
the most
of f-he effect
of muscle
is the moment
of force
(torque)
which
the
immuscle caim exert-. Time nmomehmt of force immvolves the tension
immthe muscle,
labeled
useful
nmeasure
F in
4-B,
Figimm’e
multiplied
by its lever
arm,
labeled
1. The
lever
arm
is best
defined
as f-he length
of a perpendicular
between
the limie of action
of the muscle
and the
axis of f-lie joimmt. Iii similar
fashiomm, f-he weight
TV has a lever arm d. If the force of
gravity
acf-immg on time weight
and the force of contraction
of the muscle
are the only
forces
act-immg
on f-his body
segmcmmt,
no motion
will occur
if F X 1 + W X d = 0.
Whemm accelerat-iomms
occur,
they cami be included
iii these
referred
to either
as effective
forces or inertia
forces.
,Joint
Gompi’ession
and
calculations
amid
are
Stability
Muscles
amid joiimts funictiomm immclose cooperatiomm.
The joints
assist
the
lYT mmmeammsof arficular
surfaces
mvhicim guide
the nmovemmmemmts that the muscles
ing
to
prooluce.
l)roviole
fh
deltoiol
forth
Time
sf-ability.
shoulder
when
the
immtime scapula
I’igure
of the
1mm f-his
mmmuscles are
commiplef-ed
the
deltoid
the
pull
axis
in
the
Figure
5-A
of the
deltoid
mmmuscle pull
joimit,
commjunct-ion
in
of the
deltoid
mmeuf-ralize
commmpressive
by
the
force
addif-iomm
other
forces
exerted
cuff
labeled
but
arc
wit-h
commtribute
added
by
of gravitational
to
f-he
that
THE
of the
calls
reaction
the
constitute
to
equal
hummmerus
passes
well
conic
to
I. Their
a
rotate
and
(miot
the
opposite
shown
f-he
effective
JOURNAL
outside
in the
f-he
the
rescue.
mmmonmemits of
additive
of
commibimmed
arid
action
acromiomm
to joimit commmpression.
The
vector
which
portrays
muscles
S arid
the
of f-he muscle
omi the
compression
rotator
each
Wimemm these
shoulder
joimit to
the
on
muscles
are try-
the
of
shows
amid joimit
f-he teimdemmcy
5-B,
Figure
coml)ressionm
mmmeasures
pull
to
sifuatiomi
showmi
commmpressiomi.
resulf-amit
Time
mmmeasures f-he comitributiomi
of the deltoid
5-B shows
a more
perilous
situatiomi.
,
conf-ribimtiomm
time joimit
in
to the
sufficient
as amm exammmple.
joimmt ; together
reactiomi
This
reactiomm
lai)rummm.
serve
provide
is elevated.
mmmommmetmt
of which
scapula.
diagrammm)
imi refurmi,
will
humerus
imm the
a reacfiomm
couple,
mmmuscles,
joint
the
then
nmuscles.
Two
force
cuff
about
s amid i, to joint
forces,
o!eltoio!,
the
glenoid
we
Time
obtain
picture
R, the
cami
forces.
OF
BONE
AND
JOINT
SURGERY
be
HERBERT
ELFTMAN:
BIOMECHANICS
OF
5-A
FIG.
369
MUSCLE
5-B
FIG.
Fig. 5-A: Commtributiomm
of the deltoid
muscle
to stability
of time elevated
by time reaction
to time pull of the muscle
passimig
well withimm the glemmoid
simoulder
labrmmm
joint.
joimmt is shown
to compress
the
.
Fig. 5-B: Imi this position
of the shoulder,
outside
time glemmoid laI)rnmm.
Time addition
balamice
but
their
joimit rea(’tiomms
(s amid
nmore favorably
placed
for joimmt stability.
timid effective
forces
are also iniportant.
the reactiomi
to the pull of time deltoid,
D,is
located
well
of two
cuff nmimscles,
S amid J,wmthi
them.r mimommmemmtsin
i) additive
provmdes
a resultammt
jommit reaction,
H, much
1mm additiomi
to time mimuscimlar
forces
showmm here,
gravity
IN
CHANGE
6-A
FIG.
LENGTH-
CM.
6-B
FIG.
Fig. 6-A : 1ime st ret (ii-simort
cmi cycle.
I )iagranm
of t ime posterior
delt oid miiuscle
aidi mmg gravity
to
svimmg the arm at more
thami its miatural
frequency.
As the arni swimigs forward
the imiusele
is stretched
as it decelerates
the arnm with
imicreasimig
force umitil it exerts
nmaximunm
temisiomm at mmmtiximiiummmlemmgth
with
the mimotion
mmmomemmtarily
stopped.
The
nmmmscle then
shortemms,
acceleratimmg
time arnm with
docreasimig
force
umitil it agaimi passes
the vertical
position.
Fig.
6-B:
The stretch-simortemm
cycle
of the (‘alf muscles
dmmrimig rumimmimig. (Adapted
frommm Time Actiomm of Muscles
in the Body
by herbert
Elftman.
Biological
Symposiimm,
Voltimime 3, pg
201, 1941.)
Time Stretch-Shorten
Cycle
?ilammy mmmovenmemit-s of time body
immovemmieimt-s
therefore
are
first
stretcimeol
simimilar to those
illustrated
by
the
oscillation
gravity.
Figure
swings
forvarol
witim decreasing
before
6-A
accelerating
wimemm time armii swimmgs forwaro!
as it. slows
down
backwa-m’d.
Time
at
wimich
rIii
VOL.
48-A,
fume
general
NO.
the
forward
nmaxinmummm
the
velocity
sigmiificaimce
2, MARdI
1966
are
such
that
Time
ommaim oro!immary
of an arm forced
shows
time arnm first
velocity
until
backward.
l)ast
Time
the
swing
force
time mmiuscles
themm simorten.
of gravity
ai(lihig
posit-ion
amid
timese
these
muscles
are
amid mmmay, indeed,
a higher
frequeimcy
imm a
vertical
posit-iomi
by
be
mmmuscles
fm’oimmwhich
it
mmmoimmeimtam’ilyat il-s u)permmmost
deltoid
posit-iomi
mmiuscle
wimicim control
of
to
posterior
amid fimially
imi time
pemmdulum
it stops
vertical
act-iomis
mmiuscle
becomimes
; time immuscle is timen
shortemms
is exerteol
as it accelerates
at- ifs
active
stretched
time swing
mimaxinmumim
lemigth,
is zero.
of this
stretcim-simortemi
cycle
is further
enmpimasized
by
370
A.A.O.S.
1igure
6-B,
siomi
which
iim hot-li
crease
is based
lemmgt-h,
with
as
f-he
this
tion
frommm time work
mmom’mimalsequence
Two-Joint
with
gemmerosity
will
of niore
be used
during
the
for
stretched
by
this
muscles
tend
events
takimmg
is what
is suppheo!
the
cunmulative
actually
to
pass
place
fiber-lemigth
in all
over
being
IN
tensiomm imi one muscle
sequemmce.
stretched
amid
in omme nmuscle
are
shortemmed
Figure
7,
they
at
which
are
ammother.
records
hip
7
of two,
shortemi
If separate
receivimig
elimimmate
more
slowly,
kmmee flexors
amid hip
energy,
amid the hip
this
duplicatiomi
of
amid follow
the mmormal
.
dissipatiimg
imistead
emmergy.
arid
follow
muscles
of two
The
the
are
hanistrimmg
mmormal
that
; short-emmimig
are
expenditure
left
amid
to the
control.
less efficient
Basic
tainied,
suggest
that
mmmuscle
cami do
stretch-shorten
temisiomm is produced
is slower
timan
all
this
sequence
imi the
as
ahmd mimaimionc-joimmt
mmmus-
by temmdomm action;
It is therefore
mmot
f-he nmuscles
of the hunmami body
are orgammized
imito lomig nmuscles
amid able to perform
the gemmcral actiomm imitcmmded with efficiency
of emmergy
represents
is usually
nmammy joimmts
movcnmemmt
The
two-joint
additiomm
would
a fashion
they
by
This
they replace;
emmcrgy is tramisferrcd
fronm omme joimit to ammother
the stretcim-shortemi
cycle,
with its advamitages,
is achieved.
timat
over
rummninig
If ommiy omie-joimit mmmuscles were available,
a hip
shortemmimig
arid doing
positive
work,
while
a kmmee flexor
trememmdous
emmergy-saving
showmi
in the figure.
The advamitages
of two-joint
spamimmimig
pass
LENGTH-CM.
instead
with
surprising
which
muscles
joimmts.
nmimscles.
Actual
records
of rummmiimmg .
the knee
muscle
would
be stretched,
work.
The
hamstring
muscles
(right)
amid kmiec nioniemits
during
extemisor
would
have
been
walkimig
confirmmma-
The term
simice the
immtwo-joimmt
the
while
is illustrated
FIG.
both
ole-
suggest-ion
received
mimuscles
joimmt-s immsuch
at omie joimit
happemis
Emmergy-snivimig
by two-joimmt
extensors
were employed
(left),
muscle
WoUld
shortemm,
doing
effort, maintain
stretcim-shortemi
with
movememit
CHANGE
des
arid
has
by
The
mmo mmew principles.
allow
the
time body
beemi mmoted that
to
two-joimmt
taimmed
is followeol
shortemmimig.
time muscle
in temm-
increase
emmergy,
the usefulness
of this arrammgenment.
mnore than two joint-s are immvolved,
immdicates
already
mmot sufficient
was
rfhe
.
absorbs
subsequemmt
sommme energy
which
evemi when
joimmf-s aohis
It has
rfhat
published
amid
of Hill.
timaim omie joiimf-
that-
previously
is stretched
saves
LECTURE
Muscles
rfie
muscle
COURSE
on a figure
mimuscle
lcmmgfim amid f-cnsiomi
that-
nmore
INSTRUCTIONAL
siimmplest
forward
the
type
The
finer
short
nmuscles.
Factors
in Gait
adjustnmemmts
of gait,
from
which
all other
surface.
Once
the average
omi a level
pattern
a repetifiomm
of gait
of
the
repeats
first
itself
except
JOURNAL
the
details
of
types
can be approached,
is
forward
speed
has beemm oh-
every
two steps;
for the exchange
THE
of
OF
evemi
of left
BONE
the
for
AND
sccommd
right.
JOINT
step
SURGERY
HERBERT
:
ELFTMAN
BIOMECHANICS
FIG.
OF
371
MUSCLE
8
Saliemit
features
of an average
step
modeled
after
Fischer’s
secommd experinment
16#{149}
The body is
divided
immto three
cardinal
parts:
the head,
arms,
and
trunk
(HAT)
and two
lower
extremities,
for each
of which
the center
of gravity
may be followed
with simfficiemit
accuracy
by a parallelogranm
constructiomm
at the kmmee. Phase
1 shows
beginning
of double
support
with
relative
swimmg of lower
extremities
completed
and body
center
of gravity
almost
at lowest
elevation
and
maximum
forward
speed.
Phase
2 shows
maximum
speed
of swing
of extremities
with
respect
to each
other
amid
the body
center
of gravity
approaching
highest
elevation
amid mimiimum
forward
velocity.
The last
t\V() piiases
repeat
the first
two but with
left foot imi contact.
The
nmovements
movement,
such
during
as
the
gait
be
can
rhythmic
comisidered
swing
under
of arms
and
two
legs
imeadimmgs:
relative
to
intermial
each
of-her
without
changimmg f-he position
of the center
f-he body as a whole;
amid external
movement,
of gravity
or the angular
mommiemitumim of
the translation
of the center
of gravity
of the
this
are
body
amid rotation
of the
body
illustrated
in Figure
8. The
lower
nmemmt at phase
body
cemiter
which
1 (left)
of gravity
is relatively
Control
small
of Internal
Control
are
respect
their
swing
to each
kinetic
imm
it at phase
is showmm
a nmajor
portiomm
anmoumit
of energy
emmergy
emmergy
expemmditure
48-A,
NO.
external
camimmot
result
the
curves
2, MARCH
of work
must
swimmg
imm the
camm
1966
done
by
of the muscles.
flow of kinetic
emmergy
that
16
move-
nmovemmmemmt of the
of the
be accomimplisimed
body
as a whole,
alomie
lower
be decreased
is
muscles
of
by
part
forces,
ammo!
increase
arid
decrease
in kimmef.ic cimergy
amid
the
succeeding
dewith
as the
decrease
In both cases nmctabolic
energy
is useol.
energy
of internal
movehmment
represents
expenditure
be supplied
by extermmal
with frictiomi
amid plastic
of the lower
extremities
other,
as shownm in Figure
8, immvolves
alternate
energy,
as showmi iii Figure
9. The immcrease
of
nmovemenfs
imiternmal
by Muscles
movcnmemmts
lower-extrenmity
kinetic
VOL.
3. The
relative
; f-he rotatiomi
accomplished
almost
emmt-ircly by muscles,
cmmt-erimig to a lesser
degree.
The swimmging
is the
of these
their
is imot showim.
Move,-nents
accelerates
for
space
Some
start
amid complete
is accommmplished
by stretchimig
Commfrol of the ebb and
step
center.
extremities
through
here,
of immternmal
so they
formation
about
the
nmuscle
represented
of
wit-imout
Figure
body
durimmg
gait
amid themm removed
by the nmaxinmum
9.
altcrimmg
The
ommly way
average
velocity
Time
during
value
imi whichm
mmet
each
of time
this
amid lemmgth
372
A.A.O.S.
INSTRUCTIONAL
COURSE
LECTURE
C-)
0
m
Li-
0
Li
+2
z
U)
+1
Li
.-J
0
w
RO
LS
LO
FIG.
RS
9
changes
for time step simowmi immFig. 8. The upper
grapim shows
how the kimietic emiergy amid
emmergy of the body
as a whole
conmpemm.sate
durimig
the step. The curve
labeled
KER
is the
mirror
image
of the KE
curve;
if the PE curve
coimmeided
with
the KE!?
curve,
time nmuscles
would
mmot need to supply
amiy emmergy for movememmt
of the body
as a whole.
The lower part of the figure
shows
the kinetic
emiergy
of the
relative
niovenmemitof the lower
extremities
with respect
to each
other.
This
emmergy nmust be supplied
by nmuscie.
Energy
potemitial
of ste1)
to flatten
iS
the
out
kinetic
emmergy curve
by
providimmg
fall. Time limit of emmergy-savimmg
by this device
is shown
by
lower
part of Figure
9. This
situation
cami only
be obtaimmed
celeratiomm
to
Internal
swimmgimmg,
ami average
during
tiomms
process.
of the
of External
external
mimovenments
to those of time imiterimal
The
are
Movement
trunk
and
mmot restricted
timey
to
comitribute
the
of ammy extremity
head,
a commimon
and
lower-extremity
immajor
may
part
also
occurrence
Movements
of time body
mimovememmts,
by Gravity
during
except
and
be
of
imi nmammy types
Muscles
the body
as a whole
are exaggerated
in abmiormal
mmornial gait as well, if for mmoother
reasomi thamm the
gaits
but are importammt
great
care which
nmust be
exercised
to mmminimize them.
Guarded
rotatiomm of the hips, for immstammce, lessemis
lever armmi by wimicim the ground
reactiomi
affects
total
vertical
spimm.
Time translation
of the cemmf-er of gravity
of the body
during
gait is shown
Figure
are
8. Althougim
time
gravity
energy
variatiomis
the
balanced
level walkimmg go through
cycles
for forward
tramislatiomi.
Time rota-
of
ill the
rise
gait.
Control
similar
walkimig
mmormmmal i)erforniamlce
energy
involved
in this
by a coummfer-miiovemmienit
of disordered
rapid
velocity.
mmmovcmmmemmtsduring
but
a mnore
time dotted
himme in the
by immstanitammeous
ac-
vertical
its lateral
umidulatiomms
umidergoes.
of time body
ill potential
The
forward
as a whole
mmmovemmmcmmtsare
ammo! chammges
velocity
amid time vertical
immmportant,
imm forward
is
time
of mmmuch greater
which
velocity
largest
ummdulat-iomms
commtributor
are
the
ccmmter
time
images
JOURNAL
OF’ BONE
AND
JOINT
of
kimmetic
of the
emmergy.
THE
in
significance
to
faithful
the
SURGERY
HERBERT
Time vertical
in
movememmts
8 amid are
Figure
potential
tigators
also
fumictiomi
to
of muscle
Immstead
of
each
that
step
OF
of gravity
I)otemitia!
curve
impressive
is the
foe
373
MUSCLE
of the
energy
are
gravity
is to battle
muscle
cemiter
as the
during
envisage
BIOMECHANICS
of the
shown
energy
2,28
ELFTMAN:
body
are
in Figure
and
led
of efficiemmt
amid that
body
were
to
gravity,
KER
curve
PE
imives-
time mimajor
gravity.
combating
follow
time actual
imm
changes
imiammy early
gait
however,
it
camm be
seemm froni
that time kimmet-ic energy
of the body waxes
arid wammes so as to cooperate
in keeping
the total energy
of the body relatively
constammt.
If f-he rise
following
depicted
9. The
curve,
(the
the
mirror
muscles
image
would
of
KE
the
Figure
instead
curve)
mmeed to commtribut-e
9
with gravity
amid fall of the
miothiimg
of
to
the
H
H
C
FIG.
FIG.
10-A
FIG.
10-B
10-C
Fig.
10-A: Basic fundamentals
of muscle
control
of the trajectory
of the body as a whole by det-ermining
the ground
reaction.
The square
represents
the mass
of the body
as a whole
with
an arrow
for its instant
velocity.
The ground
reaction(R)
is the result of the reaction
to gravity
(G) amid the
effective,
or inertia,
force (A) reflecting
the acceleratiomi
of the body. The body is vaultimmg through
space
on a rigid
rod,
the reaction
is perpendicular
to the trajectory,
and
the chammges
in kinetic
emmergy are due to gravity.
Fig.
10-B:
The ommly change
is to show
a lower
extremity
requiring
muscle
momemmt.s,
H,K,
amid A,
to keep
it rigid.
For simplicity
we shall
regard
this extremity
as weight-less.
The
muscle
momemits,
H,K,
and A are proportmonal
to their lever arms, h,k, and a. The muscles
use metabolic
energy
for
tension
maintenance
but do no physical
work.
Fig. 10-C: Action
of the muscles
changing
the trajectory
of the body. The ratio
of muscle
moment.s,
dictated
by the nervous
system,
determines
the position
of the groummd reactiomm
amid the
magnitude
of the muscle
moments
determines
the acceleration.
exterimal
energy
center
of
of gravity
management
imi
which
of the
body
way
movememmts
weight
the
limbs
effective
weightless
ground
the
acceleratiomm
tial
emmergy
management
A
to simplify
,
cooperate
is illustrated
in a box
OIi a pole.
force,
resulting
muscles
“
concentrated
as if vaultimmg
Skillful
body.
the eniergy
that
for the normal
walker
is easier
The
body
the
which
reaction,
of the
immf-erchmammge.
the
of the
muscle
must
than
for the
minimizes
with
gravity
in Figures
10-A,
surrounding
details.
the
trajectory
of the
contribute.
anmputee.
in controlhimmg
10-B,
center
In Figure
10-A,
the
amid 10-C,
body
external
which
of gravity
the
body
rflmis skillful
amid
depict
comisider
moves
forward
The external
forces
are the reaction
to gravity,
G, amid f-he
is the product
of the mass amid acceleration
of the body.
The
R, is perpendicular
to the instant
velocity
of f-he body,
body
No
is derived
muscle
cmmt-irely
activity
from
gravity,
is immvolved.
amid
kimiet-ic
amid
potemm-
374
A.A.O.S.
Iii
Figure
10-B
the
INSTRUCTIONAL
pole
has
COURSE
beemi
replaced
by
simowmm. rrlme ground
reactiomi
has miot changed
through
time figure (dotted
himme). It is necessary
tiomm to
ankle
1)revemmt
further
Plammtar-flexor
a. 1mmthe same
arnm,
tively,
can
tiomm of the
nietabolic
doing
be
flexioim
muscle,
way
the
calculated.
of action
emmergy
to
lever
of the
various
arms
nmaimmf-aimm tension
to the
kmiee
of the
t
but
segmemits,
joimmt-s. The
of the
reaction,
body
ammgulateo!
as
amid its line of action
is projected
for mmiuscles to be in isometric
contrac-
be equal
must
monmeimts
The
hue
mmophysical
of the
A,
LECTURE
amid
are
hip
muscles
amid s, arc
riot
mmiomemmt of force
reactiomm,
R,
amid
chammging
of the
time
K arid
muscles
showmm.
timmies
lever
H, respec-
the
lmoimmt-s of imit-ersec-
The
muscles
length
and
are
usiimg
therefore
are
work.
3
#{247}
VELO
FIG.
Emmergy
comisunmption
fronm the experiments
bolic energy,
above
iii walking
at various
CI IV
11
combimmatiomis
of Atzler amid Herbst
The
that used in standing,
required
contour
of step
lines
lemigth
of the
amid velocity,
nipper
graph
replot-ted
show
weight
the meta-
to move
omme kilogram
of body
omme meter
The mimminmum
emiergy
expemiditure
for each
velocity
is shown
by a limme which
passes
amid mmear E amid F, which
refer to the steps
ammalyzed
by me 8 amid by Fischer
16.17,
The lower graph shows the emiergy consumptiomm
above
that
for stammding
plotted
in two ways.
The
solid
limme simows
the COSt imm calories
of trammsportimmg
omme kilogram
of body
weight
omme horizontal
meter;
it ha.s a defiumite minimum
where the efficiemicy of the locomotor
apparatus
is greatest.
The
hrokemm limme shows
emmergy comm.sumptiomi
immcalories
per kilogram
minute;
whemm the ba.sal
expemmditure
for stammdimig ( 17.2 calories
per kilogram
mimmute)
is added
to this
it reflects
the stress
to which
the
body is subjected.
horizommtally.
through
0.50
In Figure
has
10-C,
stinmulateol
about
action
H, K,
time imiuscles
enough
motor
assertimmg
positive
provide
commtrol.
The
mmmonments of force
mmervous
systenm
(H,
amid A)
K,
hip,
kmmee, amid ankle.
Simmce a weightless
hinmb is assuimmed,
time ground
rewill be the same for each joimmt. When
the mmcrvous systemim produceol
momemmts
ammo!A , it deternmimmed
the direction
of the groummd react-ion
by their
proportions
the
amid time mmmagmmit-imdcof the
ommly upwaro!
arni
arc
ummits to
with
acceleratiomm
respect
to the
acceleratiomi
by their
mmmagmmitudes. rFhe result
but also amigular
acceleration
simmce the reaction
body
center
will
be
has
a lever
riot
of gravity.
THE
JOURNAL
OF
BONE
AND
JOINT
SURGERY
HERBERT
ELFTMAN:
Energy
A detailed
the
amialysis
physical
of the
work
systenm
Such
also
therapeutic
are
procedures
ummusually
An
1 1.
vel1
Herbst.
The
Their
subject
of gait
the
metabolic
for
tensiorm
consumption
the
information
metabolism
under
experiment
of this
at each
riot
It is important
mmmoveniemit
mmmore
tracteol
frommi that
The
solid
to mmote that,
the
accurately,
durimmg
hue
mmiemmf-s
choose
upward
the
of these
in order
optimmmummmline.
1mmthe lower
part
evaluatiomm
This
this
of the
calories
curve
sort
have
The
by
curve
requirement
to f-he
distance,
and
Ralston
taneously,
motor
there
unit
are
fibers
for
of motor
units
of fibers
in each
miumber
was
ummit imm the
susceptible
number
the
right
represents
able to walk
effect ommcmmcrgy
the
of
in a muscle
unit,
of increnmemmts
belief
but
the
to
Imi the
to determine
(solid
himme).
of
gaits.
limme) shows
would
to
Measuremmmenmts
emiergy
time olata imi the
This
nmethod
of
peak
the
to each
load
be
that
immdicaf-cd
restimig
by
sfandimig
value
is mmthe
emiergy
on time gra)h.
of Muscles
that
mammy muscle
fibers
mm a given
nerve.
The mmumber of muscle
fibers
few fibers in each unit of the extraocular
gastrocmicmius
13
motor
that
muscles
by
the
with
commtrol.
nmay be a better
number
Although
ummit always
graduated
simmce the
which
useful
1 1 (broken
added
(‘lose
ways.
horizontally
by multiplyimig
by the velocity.
mimmute,
very
two
of abmmornmal
instance,
in each
closely
iii
shape.
efficiency
is so arranged
per
number
mmmuscle activity.
of the
beemi sub-
corresponding
meter
evaluatiomm
for
Control
all of the
the
ated
are
for
was
were
16
it is most
one
kilogram
fronm each
motor
varies
from the
the
semiting
data
cost
has
to
velocity
of Figure
heart,
per
subject,
is justification
more
f-he
part
calories
fibers
that
left
(F)
a characteristic
for
lower
of muscle
1600
rcasomm to believe
from
commsunmptiomi
omme kilogram
Nervous
muscles
emmergy
standing
of Fischer
imi goimmg a given
upomm the
muscle
receive
branches
each of these nmotor units
amid that
omie mvhemm it is not
if 17.2
inrmervatiomm
the
only velocity
in nmef-abohisni
mmmeasureThe assunmptiomm
that an individual
will
is not always
true,
although
it is interestimig
against
for f.imis particular
The
Atzler
values
shown
horizontally
the
subject
graph
nminufc
amid is obtained
per kilogrammm meter)
placed
f-he graph,
the
is plotted
the
iii
kilogram
(calories
Time load
8
mimmimum
is f-he mimost useful
on
to represent
1 1 , time energy
above
done
heemm used
secommd
portamit.
values
of Figure
a definite
commsummipfiomi per
curve
below
this
plottimmg
(E)
nmine
up in transporting
has
by
by
provided
The
weight
of step at which
this subject
lemmgth of step has a profoummd
conibimmationi
graph
work
used
performed
is
27
conditions
combinations
of the
across
exl)erinmemit.
subjects,
imi the
different
custommm of reporting
efficient
historic
two
optimmmumim hue
the
usual
imm amm imiadequate
thie nmost
that
of
available
walking.
sweepimmg
; the
results
nmaintemmance.
controlled
was
out
two
replotted
in the upper
part of Figure
combinations
of length
of step
and
nietabohismmi
the commmbinmatiomms of speed
amid length
mmiost- efficiently
at each velocity.
The
comisummmption
and
usually
type
take
of these
advamitages
frommm which
the contour
lines of this figure
were commstructed.
the emmergy immcalories
used for movimmg omme kilogram
of body
omie immet-er.
they
only
productiomm
the
comimputimmg
energy
cost
of
but
involves
7,8,10
physical
understanding
of over-all
desigmied
the
data
that they
collected
are
walked
at twenty
different
; his oxygen
velocity
an
mechanisms,
restricted
to a measurernermt
meamms of oxygen
consumption.
and
requirements
needed
for
and
in Walking
and
energy
is desirable
375
OF MUSCLE
in shortening,
stretched,
of the
aim analysis
energy
by muscles
as they
but
fumictiomis,
Consumption
of the
done
BIOMECHANICS
index
there
fewer
of effective
systemmi
simul-
fibers
f-he
iii
other
camm recruit
each
hand,
control
of ummits commmes closer
miervous
is rio
commtract
On
in
thamm
to repregradu-
376
A.A.O.S.
Time feedback
fummctiomms 25
two
maimmtenammce
orgamis
of information
Omme is regulation
contraction
; this
muscle
spindles,
of
amid the
feremmt fibers.
The
cermmimig how
well
infornmationm
mmmay or
sensory
other
the
may
problems
in
COURSE
is feeding
to the
is succeeding
not
LECTURE
concerning
muscle
of intrinsic
factors
regulation
is mediated
which
have
gamma
function
nmuscle
termmmimmatiomis from
\-lanmy
INSTRUCTIONAL
reach
mmervous
immproducing
go to a variety
of locomotion
progranm
nmore information
time
complicated
be obtained
actioims
concerning
the extent
and the time it takes
effect nmodulafion.
The ordinary
are too short
for the production
OIl which
part
be applicol.
can
of the
contractions
of a tetanus
succeeding
cycles
Future
iii the
The
immformation
classic
methods.
sequence
ciated
with
other
criteria
The use
of devices
motor
pattermis
bodies
is a challenge
an even
to
for the
informatiomm
broader
new
sources
froni
current
goes beyond
by a variety
spectrum
activity
will
of tension
data
production
Harmonious
will
concerning
the
if it can be asso-
useful
variations
in muscle
power
presents
the
of energy.
that
available
of experimental
of instrumentation
has contributed
become
more
monitoring
of the electric
using
external
The
resemblance
It is essential
of Study
future.
of action
contractions.
the commtrol
Methods
that
bears
slight
laboratories.
of muscles
during
mmormal movements
and it would
be interesting
to know
afferenmt
Electromyography
of muscle
groups
but
centers.
ummsolved.
24,
contained
in the present
paper
by adding
later data gathered
immthe
comm-
movememit.
This
by a variety
of
to which
the higher
centers
for feedback
inmforniation
to
23,29
It is to be expected
be employed
information
of higher
remain
elegamit
perfornmance
of which
human
beings
are capable
to the primimitive
reflex movements
studied
in physiology
that
system
the desired
and is served
comisciousness
which
messages
the neural
control
contraction
presumably
has
within
the muscle,
such
as
largely
by the Golgi tendon
efferent
fibers
as well as af-
in non-isometric
as sources
possibility
function
of signals
of linking
for
old
of reconstructed
to biomechanics.
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under
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amid Pathological
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A mmumber
S. Reich
omm The
Reconstruction
The
whether
of typographical
Selection
(High
first
recent-
On page
line
or
205,
errors
of Patients
Osteotomy
of text
203
is still
legend
for
should
.
.
Fig.
VOL.
48-A,
page
NO.
209,
7, second
Reference
2, MARCH
1966
Hip
Imistructiomial
Fractures
Graft
or Both)
read
“The
Course
for
in the
Lecture
Prosthetic
or
Jammimary
treatment
1966
Other
issue
of fractures
of the
for
23.
.“
3-C,
On page 207, 25th line of text, for Haa.s
On
in the
with
or Bone
on page
unimnited,
immthe
occurred
line,
next
to the
read
Ha.ss.
for
945-955
la.st
read
line,
745-755.
28 read
by Dr.
Types
of The
femoral
Rudolph
of
Hip
Joimrnal.
neck,