Local muscle
and occluded
endurance with open
intramuscular
circulation
K. B. START
AND ROSEMARY
Faculty of Education,
The University
M7estern Australia
publication
I
g October
l A test of maximum
strength
probably
gives
of the number
of contractile
elements
that are
muscle
that
rather
submaximum
than
its
immediate
tensions
resources
can be produced
more indication
available
in the
of energy.
The fact
and maintained
for
a finite
time subsequent
to a maximum
contraction
which
can be
maintained
for a transitory
period
only,
indicates
that
it is not a
question
of energy
exhaustion
alone.
Thus in any correlation
which
might
exist
between
strength
and
high-load
endurance,
the relation
might
not be simply
on the basis
of the common
energy
supply
unless
a maximum
contraction
is only
developed
when
all
the available
fibers
are contracting
at their
maximum
rate
and
the outward
response,
in the form of the external
tension
generated,
takes
some
time to build
up. Even
in the latter
case strength
de-
1962.
804
Downloaded from http://jap.physiology.org/ by 10.220.33.3 on September 12, 2016
D
either
isotonic
or isometric,
a
URING
EXERCISE,
muscle develops a tension which appears externally
as a
force and internally
as an increased
intramuscular
pressure. This pressure tends to compress the walls of
the capillaries,
venules, and arterioles within the muscle
tissue while these are maintained
open by the pressure
of the blood which the heart is sending through
them
(r-4).
However
it is evident that during
contraction,
a muscle is capable of developing
intramuscular
pressures far in excess of the blood pressures generated
by
the heart and as a result, as the muscular
tension rises
and the intramuscular
circulation
is compressed,
there
comes a critical
tension at which these blood vessels
are occluded
(5-7). The value of this critical
pressure
could be expected to vary with the individual’s
systolic
blood pressure at the time of the exercise and the response
of his vascular bed to the exercise, but norms for these
occlusion pressures have not been prepared.
It is certain
that in maximum
and near-maximum
contractions
of
normal skeletal muscle the tension developed is sufficient
to produce
intramuscular
vascular
occlusion
and the
question
becomes one of determlning
at which
subfor
Nedlands,
maximal
level, perhaps
expressed as a percentage
of
maximum
strength,
the critical
occlusion
tension
is
developed.
It has been variously
suggested (7-g) that
a contraction
equivalent
to two-thirds
of maximum
strength produces occlusion,
while Barcroft
and Millen
(2) concluded
that a contraction
need be equivalent
to
only one-fifth of maximum
strength to have this effect.
It appears that more work in this area is required
before
a final understanding
of this situation
is achieved.
The maximum
effort of a single muscle is assumed to
call into play all the fibers under the immediate
volitional control of the subject. The number of such fibers,
their degree of hypertrophy,
the efficiency
of their
neurological
organization,
and the frequency
of their
contraction
govern the external
force generated
in a
“maximum
voluntary
effort.” With a submaximal
effort
not all the fibers would
be required
and the task of
maintaining
the tension could be shunted
from one
group of motor units to another.
This in turn would
enable a submaximum
tension to be maintained
for a
longer period as in what is understood
as an isometric
endurance
activity.
If the tension
developed
in the
muscle th .ough su .bmaximal
was sufficient
to produce
occlusion
of the intramuscular
circulation
the total
energy available for the endurance
effort would be fixed
as that initially
available
to the muscle.
The same
amount of energy would have been available for a single
effort which might be indicated
by an isometric strength
test and one might
therefore
expect that isometric
strength
and isometric
endurance
would
be related
when the tension for the endurance
effort is sufficient
to occlude the intramuscular
circulation.1
Also as the
START, K. B., AND ROSEMARY HOLMES. Local mm/e endurance
with open and occluded intramuscular
circulation.
J. Appl.
Physiol.
1g63.-The
local isometric
endurance
of the
18(4): 804-807.
elbow flexors of four groups of five female subjects was tested.
Two
groups
had the circulation
to the contracting
muscles
occluded
by a pressure
cuff and the others had normal
circulations. One group in each of the open and occluded
conditions
worked
with
a load equivalent
to one-third
of maximum
strength
and the other
group
worked
against
a resistance
of
two-thirds
of maximum
strength.
The endurances
of the two
groups
working
with two-thirds
of maximum
strength
as load
were not significantly
different
despite
the occlusion
of the
blood supply
in one of the groups.
The endurance
of the group
with open circulation
and one-third
of maximum
strength
as
ioad was significantly
greater
than that of the group
with the
same load but with occluded
blood supply.
Only
at this lower
level of loading
did the artificial
occlusion
of the blood supply
to the active muscle group appear to reduce its endurance.
Received
HOLMES
of Western Australia,
FIG.
I. Modified
Kelso-Hellebrandt
ergograph
used for measuring the maximum
strength
and isometric
endurance
of the elbow
flexors
of the subjects
(diagrammatic).
METHODS
fit women
university
underTwenty
medically
graduates
comprised
the sample for this study. In the
first week the strength of flexion of the right elbow was
measured
on a modified
(IO: I I) Kelso-Hellebrandt
ergograph
(12)
by the cable-tension
method devised by
Clarke (I 3). Much discussion has centered on the optimum angle at elbow for maximum
performance
(1420),
and from the evidence of such researches and particularly
those of Graham
(I o) and Murray
(I I>: who
used the identical
technique
in their work, the angle at
elbow was established
at I I 5’ for testing.
Each subject was measured
supine, elbow at I I 5’,
with the wrist attached by means of a padded cuff to the
lever arm of the instrument
(Fig. I). Reduction
of the
elbow angle was prevented
by connecting
the lever to a
fixed point by means of the measuring
cable (I 3). In
this position
two measures of maximum
strength
of
elbow flexion were taken for each of the 20 subjects who
were subsequently
ordered on the basis of the mean of
these two strength measures and placed into four groups
as in Table I.
The isometric
endurance
of the elbow flexors of the
subjects was measured as follows. Each subject adopted
the identical
position on the ergograph
to that for the
.~-_
_-__
-..
__ - - ---velopment
would
involve
a learning
or skill factor
as well
as fiber
hypertrophy
as the first step would
be to acquire
the ability
to
stimulate
all the fibers
at their
maximum
rate and this would
be a
‘This
might
account
for
the
rapid
neurological
development.
strength
development
seen in the first week of training
and might
really
be an indication
of increase
in neurological
control
(skill)
r;ither
than any physiological
hypertrophy.
RESULTS
The data on the mean endurance
times of the four
2.
experimental
groups appear in Table
There
were obvious numerical
differences
between
the means for the endurance
scores and these means
were checked for statistical significance
by means of an
F test and the Kruskal-Wallis
(2 I)
variance
analysis.
A summary
of the data appears in Table 3.
A value of F = 5.56 is required
for significance
at the
I %, level
and thus the result obtained
from these data
is highly
significant.
This finding
agreed
with
the
Kruskal-Wallis
(21)
result where p(H)
= 13.86 and
hence within
the four groups ostensibly
there was a
fundamental
difference.
An obvious difference appeared
between group C and t he other groups while a second
Downloaded from http://jap.physiology.org/ by 10.220.33.3 on September 12, 2016
energy reserve is localized
in such circumstances,
endurance as measured
by time should be related to the
load involved.
If a tension was sufficient in itself to produce
intramuscular occlusion subsequent
artificial
occlusion of the
circulation
of the muscle should not affect its endurance
performance.
Similarly
in occluded
muscles, whether
this condition
is produced
artificially
or naturally,
endurance
should be related
to load. These were the
two hypotheses which were investigated
in this study.
Thus
each person
strength
measure.
was measured
supine: elbow at I I 5’, with the wrist attached by means
of a padded
cuff to the lever arm of the instrument.
Instead of preventing
movement
of the lever arm by
means of a tension cable as for the strength
test, its
movement
could be resisted by the attachment,
over
gears, of any desired load. Movement
of the lever arm
I 5’)
by means of two
was limited
to a 5’ arc (I IO’-I
stops. Contraction
of the elbow flexors could move the
lever from the I I 5’ stop and thereby lift any load that
was attached
to it. The subject was asked to lift the
lever just clear of the I I 5’ stop and to maintain
it in
this position against the resistance for as long as possible.
Endurance
was measured from the time the lever cleared
the I I 5’ stop until the subject could no longer resist the
load and could not prevent the lever falling back against
the restraining
I I 5’ stop (Fig. I).
The loading
factors for the groups were decided
at
one-third
and two-thirds
of maximum
strength.
Onethird was selected as the lower limit as Royce (7) had
noted that when used as a training
load it did not have
any effect on strength
development.
Two-thirds
was
taken as the upper limit as Tuttle
(8) and Royce (7)
found this training
load produced
strength
gains and
Wolbers
(9) had suggested that only at tensions equal
to or greater
than two-thirds
of maximum
were all
fibers involved.
In the second week, the isometric
endurance
of the
right elbow flexors of group C was measured using onethird maximum
strength as the loading
factor. Group
D was similarly
measured but had their endurance
load
set at two-thirds
of maximum
strength. Groups A and
B had sphygmomanometers
placed as high as possible
on the upper arm. The cuffs were inflated
to systolic
blood pressure + I 5 mm Hg immediately
before testing
and were maintained
above systolic pressure during the
test. The isometric endurance
of group A was measured
using one-third
maximum
as load and that of group B,
which
had two-thirds
of maximum
as loading,
was
also taken. In all cases endurance
was measured
in
minutes and seconds by means of a stop watch but for
ease of calculation
these times were decimalized
as
minutes.
806
K.
TABLE
strength
I. Distribution of subjects within groups and basic
data for the four experimental groups
Rank Order of Subj. on
Basis of Strength
*, 8, 9, 16, 17
Group
A
Mean
Strength*
47-8
Components
Between
sets
Within
sets
3.828
B
C
2, 7, 10,
396,
11,
‘5,
‘4,
18
‘9
44.8
45.9
2.709
2 d&go
D
4, 5, 12,
‘3,
20
45.8
24754
TABLE
experimental groups
Group
A
B
Load,
max
35
35
34
D
35
* Endurance
three
cases.
measurements
Mean
Time
Open
Open
2 -576
I .2x4
2.526
were
terminated
after
15 min
21.2069
t test analysis
A
A
Occluded
$5
B
C
D
Occluded
Open
$5
Open
y$
35
y0 Maximum
Endurance,
0.613
12 .gr8*
=
2.739
4,159
I .380
B
c
2-739
4.159
8.538
8*538
I-338
I
D
.380
I.338
7 *299
7 -299
TABLE
5. Relation of isometric endurance to load as expwssed
as a percentage of maximum strength
SD
2*97I
4’2:.
Variance
109.4808
5.1625
3
16
in
possibly existed between group A and groups B and D.
Whether the differences were significant
was approached
in two ways: a) by eliminating
group C and repeating
the F and Kruskal-Wallis
(21)
tests on the three remaining groups, and b) by doing t tests on the individual
group means. The results of these analyses gave the
figure for F for groups B, C, and D as 3.0217 (28’~~ =
3.88) while
the Kruskal-Wallis
(21)
method
gave a
p(H) = 1.52. For the 5% level p(H) had to reach a
level of 5.660. Thus without
group C the remaining
three groups were statistically
similar
and the main
difference
between
the original
four groups was that
between A and the others. In the second procedure
the
t test analysis of the four groups was carried out and is
summarized
in Table 4.
As 05t8is 2.306 and oltx is 3.355 it can be seen from
Table 4 that group C was significantly
different
from
all the other groups as was expected. It was also noted
that group A differed significantly
at the 5 % level from
group B though not from group D.2
DISCUSSION
If muscular
contraction
occurs at such a level as to
cause occlusion
of the intramuscular
circulation
then
its performance
in this condition
should not be aS’ected
if the circulation
to the muscle is cut off by means of a
pressure cuff. It has been suggested that tw-o-thirds
maximum
effort is sufficient to produce
this occlusion
of the intramuscular
circulation
and thus group D was
given endurance
work with two-thirds
maximum
loading
2 The numerical
difference
between
the means
of the occluded
and open
circulation
groups
which
worked
with
two-thirds
loading
could
occur
by chance
more frequently
than
I in 20,
thus it cannot
be considered
significant.
However
the pressure
cuff itself
must
have
had some
debilitating
effect
on the portion
of the muscle
it
covered
and this might
have
contributed
to the smaller
score
of
the occluded
group.
and
Equa .tions
the three
strength
mins
for the
closest
y =
y =
y =
where
y is endurance
0
66.67
33933
4.740
00
curves
of best fit we re derived
are given
in order
below
:
9.7 log I/X
IO.5 (log
I/X)1*08
8.73 log I/X +
in minutes
100
1.616
for
0
the
data,*
I
2
2.52
and
* For
the mathematical
treatment
to Dr. P. 0. Silberstein
of the Department
versity
of Western
Australia.
(log
I /x)~
x is y0 maximum
the
authors
are
of Mathematics,
3
strength
indebted
Uni-
while group B was similarly
loaded but had the blood
supply to the muscle group cut off immediately
prior
to the commencement
of the exercise. The endurance
times of groups B and D were found to be statistically
similar.
This agreed with Dolgin
and Lehrmann
(5)
who found that arresting
the circulation
in the upper
arm had no effect on the endurance
of strong hand grip.
This might be taken to suggest that the energy available
for the contraction
was of the same order and possibly
was available
from the same intramuscular
source.
If the contraction
of the muscle is insufficient
to
produce occlusion of the intramuscular
circulation
then
there will be both a continuous
supply of glycogen and
oxygen and a removal of the metabolites
of contraction.
Both of these facilities
should prolong
the period
for
which a given rate of muscular work may be maintained.
If however the blood supply to the contracting
muscles
is artificially
interrupted
then the energy source becomes
limited to that already in the muscle and the length of
working
becomes distinctly
finite depending
upon the
rate of work and the muscular
reserve. Thus groups A
and C worked at one-third maximum
loading but differed
in that group A had the circulation
to the active muscle
group interrupted
by means of the pressure cuff. The
mean endurance
of the groups were significantly
different which
might indicate
that, as group A with its
occluded
circulation
had a lower endurance,
group C
had access to additional
sources of energy and was not
irritated
by the accumulation
of metabolites.
In the case where the circulation
is artificially
oc-
Downloaded from http://jap.physiology.org/ by 10.220.33.3 on September 12, 2016
C
Circulation
Occluded
Occluded
rog.48o8/5.1625
TABLE 4. Intergroup
endurance data for the four
2.&k?2??Za?-y
R. HOLMES
Degrees of
Freedom
Sum of Squares
328.4425
82*59995
F=
* The
greatest
difference
in mean
strength
was
between
groups
A and B. A t test for the significance
of this
difference
was insignificant
at the 5% level
(t =
gave
t = I .27g which
2.306).
AND
3. F test on data
TABLE
SD
B. START
LOCAL
MUSCLE
807
ENDURANCE
measures and
muscle action.
provi .de an interesting
win .dow
on
CONCLUSIONS
I> The mean of the endurance
scores of a group of
women undergoing
local isometric
endurance
exercise
of maximum
with
a load equivalen t to two-thirds
strength was not significantly
different
from the mean
score of a second group who similarly
exercised with
the blood supply occluded
from the working
muscle
group.
2) The mean of the endurance
scores of a group of
women
undergoing
local isometric
endurance
exercise
with a load equivalent
to one-third
of maximum
strength
was significantly
higher than the mean score of a second
group who similarly
exercised with the blood supply
occluded from the working
group.
3) From I) and 2) it was assumed that an isometric
equivalent
to two-thirds
of maximum
contraction
strength was sufficient to produce occlusion of the intramuscular
circulation
in the contracting
muscles.
4) Of the two groups of women who underwent
isometric endurance
exercise with the blood supply occluded from the working
muscles, the group which exercised with a load equivalent
to one-third
of maximum
strength
had a significantly
higher
mean endurance
than the second group which
exercised
with a load
equivalent
to two-thirds
of maximum
strength.
From
this it was assumed that in muscles with occluded intramuscular
circulation
there is a finite reserve of energy,
the rate of dissipation
of which depends on the rate of
working
of the particular
muscle group.
REFERENCES
G. V., AND E. VON SAAFIELD.
J. Physiol.,
London
‘935.
H., AND ,J. L. E. MILLEN.
J. Physiol.,
London
97:
2. BARCROFT,
I.
ANREP,
85:
375,
‘7,
‘939.
I2
D. H. Res. Quart.
26 : 263, 1956.
3. CLARKE,
T. C., AND J. FULTON.
Medical
Physiology
4. RUCH,
p/zysics. Philadelphia
: Saunders,
1960.
Arbeitsphysiologie
P., AND G. LEHRMANN.
5. DOLGIN,
‘930.
J. L., AND J. LINDHARD.
J. Physiol.,
6. HANSEN,
287,
7*
and
Bio-
2:
London
248,
57 :
‘923.
ROYCE,
J.
Res.
Quart.
29:
204,
1958.
C. D. JANNEY,
AND C. W. THOMPSON.
J.
Ap@
Physiol.
2: 663, 1950.
C. P., AND F. P. SILLS.
Res. Quart.
27 : 446, 1956.
90 WOLBERS,
J. S. A Survey
of Some Factors
in the Development
of
IO. GRAHAM,
8. TUTTLE,
Strength
Existing
(Thesis).
II
W. W.,
and an Experimental
Between
Static
U niversity
Determination
Strength
and
of Western
Australia,
of the Relationships
Isometric
Endurance
1961.
‘3.
P. J. C. Some Aspects
of Strength
Development
with
MURRAY,
Reference
to the Relation
Between
Strength
and Muscular
Endurance
(Thesis).
University
of Western
Australia,
1961.
HELLEBRANDT,
F., 1-L V. SKOWLAND,
AND L. E. A. KELSO.
Arch.
Phys.
Med.
29: 21, 1948.
CLARKE,
H. H. Cable
Tension
Test. Massachusetts:
Brown
Murphy,
14. CLARKE,
‘5. DARCUS,
16. DOWNER,
‘953.
D. H. Arch. Phys. Med.
31 : 89, 1950.
A. D. Proc. Roy. Sot. Med. 49: ggg, 1956.
H. H. Phys. Therapy
Rev. 33: 68, 1953.
77’ RASCH, R. J. Res. Quart. 27 : 333, 1956.
18. SALTER,
H. J. Bone Joint Surg. 37B: 471, 1955.
K. G., J. W. GERSTEN,
E. C. ELKINS,
AND G.
‘9. WAKIM,
MARTIN.
Arch.
Phys. Med.
31 : 92, 1950
20. WILLIAMS,
K., AND J. SLUTZMAN.
Phys.
Therapy
Rev.
M.
39 :
‘459 ‘959.
21.
KRUSKAL,
47:
614,
W. H.,
1952-
AND
W.
A. WALLIS.
J.
Am.
Statist.
ASSOC.
Downloaded from http://jap.physiology.org/ by 10.220.33.3 on September 12, 2016
eluded then the energy available for contraction
is fixed
and the endurance
of the muscle determined
by the
amount of work that it has to perform in a given time
(the rate of working).
Thus groups A and B which have
occlusion
induced
by pressure
cuffs and which were
working
at one-third
and two-thirds
maximum
load
had endurance
means that were different
at the 5 %
This would
though not at the I % level of significance.
tend to support the hypothesis of a finite energy supply
being dissipated over varying periods of time by differing rates of work.
The detailed relation
of the load to the endurance
in
the occluded muscles in this study could not be ascertained with accuracy
from the limited
nature of this
experiment
but as would be expected it was rather more
complicated
than a simple linear relationship.
An attempt was made to envisage the graph of the data by
deriving two further hypothetical
points in the relationship of maximum
strength to local isometric endurance.
Hansen and Lindhard
(6) point out that the maximum
contraction
can only be maintained
for a fraction
of a
second. Thus if the muscle hypothetically
had been
loaded with a resistance equal to its maximum
strength
it would have had a negligible
endurance.
In an occluded
condition
without
a load, i.e., load = o % maximum
strength, the endurance
of the muscle would
be determined by its BMR and on the time scale used in this
study the endurance
time would
approach
infinity.
In this manner
four readings were noted in Table 5,
two obtained
experimentally
while the other two were
theoretically
derived.
This is obviously
a very tentative
digression
but detailed work relating
strength to endurance
in occluded
muscles might
remove
the necessity for endurance