Evening star., 1942-04-16
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Laboratory. Field
And Study.
By Thomas r. Henry.

BY Thomas II. Henry.
how lons7
This question, whicn may become OF
vital significance in Americas war ef-
fort, Is answered in part in report TO
the American Medical Association by
DR.. A. C. Ivy of the University of
Chicago.
Work. he explained, can be measured
in terms of the rate at which the body
burns up fuel to provide energy-the
metabolic rate.
The normal basal rate Is between
1900 and 1900 cslories. This is the
energy OF keeping alive, used up when
the body is completely at rest. Any
exertion results in some increase. 1t
now is generally agreed, DR.. Ivy says.
that the maximum exertion which a
man can endure steadily for eight hours
Is that which increases the energy pro-
duction about eight-fold. If continued
over long period the result is collapse.
Actually, he says. no such demand
ever Is made on q worker in American
industry. Some tasks, like forced
marches under heavy loads. may rep
resent close approach. An increase
between three-fold and eight-fold may
be considered heavy work"
Such work performed over an 8-hour
period. he explains, requires diet con-
tanning from 800 to 1900 calories
above the basal requirements. The
special requirements are for increases
In fats and carbohydrates. such as su-
gar, which easily are burned by the
body.
Extra vitamins may be required. he
points out, because various elements of
the complex are necessary to burn
sugar and sweating increases the need
for vitamin c.
Most OF the labor in modern fac
tory or office, he says, can be considered
as moderate work" which produces a
metabolic rate of less than three times
the basal metabolic rate. The increase
In oxygen consumption, in heart rate
and in blood pressure are slight. The
oretically such work might be kept up
for much more than the normal work.
ing day.
But, DR.. Ivy points out, much factory
work involves constant standing and
the use of special or small groups of
muscles. The burden on the nerve
system of the muscles is intense.
Even standing" he says, lis fatigu-
Ing. 1t Is well known that the adapta-
ton of the circulation of man to stand
Ing still is imperfect. Only the physi-
cally mt can stand for long periods. The
expenditure Of energy is only about Is
to so calories above the basal rate but
the motor nerve endings may undergo
fatigue and the nerve endings in muscles.
tendons and joints undoubtedly are af-
fected.
knowledge regarding one of the most
important aspects of work, the time
required for and the factors concerned
in recuperation. is very meager. Some
evidence indicates that an athlete after
10 seconds of maximum exertion may not
be fully recuperated in an hour. It is
believed that runner cannot do his
best daily, and some believe not even
weekly.
In hand tests in which small muscle
groups are used and the work is car
ried to exhaustion, the average recovery
In group Of subjects is 80 per cent
complete in 10 minutes and 95 in 20
minutes. In tests on the stationary
bicycle, in which the subject does con-
tinuous heavy work as long as he can
maintain the same degree of work. nv
associate and I find that recovery in
10 minutes amounts to from As to IS
per cent.
"Meager data indicate that the re-
covery from the fatigue effects of mental
work resembles that of muscular work.
One investigator found that in repeti-
tive mental tasks the optimum rest Pc
riod was 2 minutes for each hour of
work, or minutes for each two hours"
In both the British and German war
efforts to date, he points out, long hours
have been reduced as much as possible
because Of the finding that they actu-
ally result In a decreased production.
1t may be due, he stresses, to the phe-
nomenon Of "staleness," familiar to every
trainer of athletes but the physciologi-
cal principles of which are not under
stood.
Development OF a new chemical treat
ment for protection of stored grain has
just been announced by the University
of New Hampshire.
1t appears to be highly effective In
preventing loss from weevils, grain
beetles and other pests. The treatment
is the result of three years intensive
work
The new chemical is chlorinated nj
troethance. 1t is a clear liquid which
can be shipped safely in ordinary con-
tainers. 1t has a distinct but not OBJ
noxious odor. 1t vaporizes readily on
exposure to air and the vapors will
penetrate through -four, grain and many
other products. While these vapors will
kill insects, they are not as hazardous
to human beings as other fumigants.
The penetrating property of the va
pors is extraordinary. For example, they
will penetrate -four stored in tight paper
bags. They will go through tightly COM
pressed cotton, or other textiles. Also.
they will go through waxed paper wrap
pings around packages and through the
nn ~ ~ t.. III