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ment of antagonist muscles, one of
which lengthens under tension whenever
the other shortens.
Soon after the work of 1951
was
finished, an attempt was made by three
of my colleagues (9) to see how the
physiological
expense
of
“negative”
work in man compares with that of
ordinary positive work.
At that time
research workers were not so certain as
they are now that stretching a muscle
during contraction can cause a reversal
of chemical processes, and they were
more cautious in interpreting what they
found than they would need to be
today. Their results, indeed, were quite
unexpectedly large and were certainly
due in part to the fact that the force
exerted by a muscle while it is being
be examined critically in further experiments on man.
The original experiments were entertaining ones to make, or to watch. Two
bicycles were arranged in opposition;
one subject pedaled forward, the other
resisted by back-pedaling. The speed
had to be the same for both, and (apart
from minor toss through friction) the
forces exerted were the same. All the
work done by one subject was absorbed
by the other; there was no othersignifi-
cant resistance.
The main result was
evident at once, without analysis: the
subject pedaling forward became fatigued, while the other remained fresh.
The rate of working was varied, and the
physiological effort was measured by
of the lines relating oxygen usage to
muscle units could be employed for a
ment was shown in 1952 at a conver-
given force.
But that is probably not
the whole story, ‘afid fhe partial reversal
of chemital reactions probably plays a
substantial part. That possibility should
bright idea, try it and see: the result
may be much more amusing than you
expected.
References and Notes
1.
rate of working differed greatly between
positive and negative work, The experisazione of the Royal Society in London
and was enthusiastically received, particularly because a young lady doing
the negative work was able quickly.
W. O. Fenn, J. Physiol. (London)
(1923); ibid. 58. 373 (1924).
2.
determining the rate of oxygen consumption. It was found that the slopes
stretched is much greater than the force
exerted while it is shortening at the
same speed, so a smaller number of
without much effort, to reduce a youn
man doing the positive work to exhaustion. It is evident now that further
investigation is necessary. But however
much, or little, the results of stretching
isolated muscles may explain the findings in studies of negative work in man,
it is interesting to see how the experiments on man arose directly from those
on toads. The moral is, if you have a
5.
6,
ao~
and balancedall the time by an arrange-
9.
A.
,
V.
Hill,
Proc.
Roy,
Soe.
58,
(London)
175
B137,
273 (1950); rid. B141, 104 (1953).
, ibid. B136, 195 (1949); B. C. Abbott,
J. Physiol. (London) 112, 438 (1951).
, Proc. Roy, Soc. (London) Bi26, 136
(1938).
B. C. Abbott, KX. M. Aubert. A. V. Hill,
ibid. B139, 86 (1938); B. C. Abbott and
xX. M. Aubert, ibid. B139, 104 (1938).
~
A. VY. Hill and J. V. Howarth, ibid. Bist,
169 (1959),
A. V. Hill, ibid. B14i1, 161 (1953).
A. F. Huxley, Progr. in Biophys. and Biophys.
Chem, 7, 255 (1957).
B. C. Abbott, B. Bigland, J. M. Ritchie,
J. Physiol. (London) 117, 380 (1952}; B. C.
Abbott
and
B.
Bigland,
fhid.
120.
319
(1954).
“F4
po (i
2
—*
ments made in an airplane.
f
US‘
nent from the observed total radiation,
Investigations of Natural
Environmental Radiation
A profile of external dose rates, cosmic and terrestrial,
has been obtained with ionization chambers.
Leonard R. Solon, Wayne M. Lowder,
Arthur Shambon, Hanson Blatz
We have reported previously the results of external environmental meas-
urements made during the summer of
1957 by members of the United States
Atomic Energy Commission’s Health
and Safety Laboratory (7). The purpose of these measurements was to
establish the approximate range of population exposures to penetrating cosmic
and terrestrial gamma radiation; ex23 MARCH 1960
By sub-
tracting the cosmic radiation compo-
posure to terrestrial beta radiation was
excluded.
In the present article are summarized
further measurements made in_ the
eastern United States and in New England,
and
a series of measurements
made in Western Europe. In addition,
cosmic radiation ionization intensities
as a function of altitude have been
obtained by several series of measure-
estimates of the terrestrial radiation
dose rates alone have been derived.
Since
ground
measurements
were
made in an automobile, an average
attenuation factor for terrestrial radiation by the automobile has been determined experimentally, and all observations, including those presented in tie
earlier reports, have
correspondingly.
been
corrected
Also reported are measurements
made in single-family and multiplefamily dwellings in the metropolitan
New York area, including three boroughs of New York City, nearby Long
Island, and Westchester County.
The ionization chamber used in the
measurements has been described in
detail elsewhere (2). This chamber has
a gas volume of 20 liters and is filled
with air at atmospheric pressure. Ioni-
zation
current
is
measured
with
a
vibrating-reed electrometer, connected
Mr. Solon, Mr. Lowder, and Mr. Shambon are
affiliated with the Health and Safety Laboratory.
New York Operations Office, U.S. Atomic Energy
Commission. Mr. Blatz is director of the Office
of Radiation Control of the Department of Health,
New York City.
90;