the knapsack and pack - bmj

193

THE KNAPSACK AND PACK AN HISTORICAL AND PHYSIOLOGICAL SURVEY WITH PARTICULAR

REFERENCE TO THE BRITISH SOLDIER

BY

E. T. RENBOURN, B.Sc., M.D.

Formerly Major, Royal Army Medical Corps

Ministry of Supply: Physiological Research Establishment of the Directorate of Physiological and Biological Research

(Continued from page 88, April issue)

PART HI

CLINICAL ATTITUDES TO PACK PALSY, PACK FRACTURE, PACK EXHAUSTION

We may divert here to review some of the more important clinical aspects of load carriage by the soldier. It has for long been known that chilling of a sweating back, when the pack is taken off after a strenuous march, may predispose not only to what is generally called lumbago or rheumatism, but also to inflammation of the kidney and lung infection. In the Effort Syndrome-the "Soldier's Heart" of the earlier authors-the load acts as but one of the "stress factors" in an individual who tends to break down even with the psychological stresses of civil life.

In 1949, Rogers (59) pointed out that compression effects may occur on the subclavian blood-vessels and brachial plexus of nerves, during their course from the neck, under the clavicle, and into the arm (Costoclavicular Syndrome or Acroparresthesia of W alshe). Such pressure may be due to congenital anomalies in their pathway, or from drooping of the shoulders as a consequence of fatigue of the shoulder muscles. In susceptible individuals, the mere carrying of a handbag, postbag or respirator may induce the disorder, with resulting pain, cyanosis, weakness, numbness or tingling in the neck, arm or hand. Stammers, in 1950, described the syndrome in new recruits, and reintroduced the old expression "Pack Palsy" (60), as used by Pringle and Parkes. In the past, this condition has been ascribed to pressure on vessels and nerves, and by tight bands and straps in the armpit. However, the axillary vessels and nerves run through the inner side of the arm, and as long as the arm is free to swing, it is not likely that such structures will be directly compressed.

The presence of bands passing high in the armpit is nevertheless indicative of a short pack situated high on the back. Since such a pack is likely to be bulky, disturbance of the centre of gravity may occur, with undue pull on the shoulder muscles, and drooping of the shoulders as a probable consequence. It would hence appear that "Pack Palsy" is essentially a manifestation of the

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194 The Knapsack and Pack

Costoclavicular Syndrome, and due only indirectly to the presence of the straps. Stammers showed the condition to arise from unaccustomed loads on the shoulders of young, untrained recruits of the weedy, asthenic type. The symptoms disappeared, in most cases, after a few weeks of outdoor life, good food, and graduated exercises for the shoulder muscles (60).

In recent years yet another disorder has been elucidated which is of interest in the problem of the load on the back. Such disorder is due to congenital weakness, present in some individuals, of the intervertebral cartilages. When these are exposed to undue compression, the softer central disc (nucleus pulposus) is dislocated, with resulting pressure on the spinal cord or its emergent nerve roots. Floyd and Silver have shown by electromyographic studies that, with full fiexion of the spine, the Erector Spinre muscles are relaxed and support of the spine thrown on its ligaments (61). Since, in gravity mechanisms, the spine and its cartilages act as a fulcrum, heavy loads on the back (especially if the centre of gravity is displaced backwards) will considerably increase the pressure on the cartilages, and in such a circumstance dislocation of a cartilaginous disc is liable to occur. This may arise not only during marching with a load, but during the lifting of the pack, or during extreme fiexion of the trunk, as with tying a shoelace. Weak intervertebral cartilages occur particularly in the cervical and lumbar regions, with symptoms referable to the neck or arm, and simulating the Costoclavicular Syndrome, or to the leg, producing a variety of sciatica.

Load carriage may lead not only to compression of blood-vessels and nerves, but on occasion even bone fracture may occur. Such "March Fracture," "Stress" or "Pack Fracture" has in the past masqueraded under a variety of names, and often been misdiagnosed. Because of the excess callus formation, it has even been confused with osteogenic sarcoma. During the Second World War the condition was shown to arise in susceptible individuals from the prolonged and repeated stresses of unaccustomed loads, especially in untrained recruits. The pull of muscles on the elastic bones appears to be the main cause, but more direct stress on bones when muscles are fatigued may be of some moment. The bones of the foot (see below) are most commonly involved, but the condition has been described in the neck of the femur, the upper end of the tibia and fibula, the hip bones, and even the ribs (62). During evolution, the adoption by.. man of the upright posture has introduced a number of mechanical disadvantages from which he has not yet recovered. The Costoclavicular Syndrome, Slipped Disc Syndrome, and "Pack Fracture" are probably some of the results of such disadvantages.

Prolonged and forced marches, with heavy and uncomfortable loads, may as we have shown be followed by such severe "Pack Exhaustion," both physical and mental, that men may fall out, or collapse in their tracks and even die. The mechanism and pathology of the condition is not clear, and hypoglycremia does not appear to be an important factor (32). But exhaustion of such a grade undoubtedly acts as a severe "stress factor," with failure of the "Adaptation Syndrome," depletion of the reserves of the suprarenal glands, and a con-




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E. T . R enboll17l

,.

1882 1888

1903 FIG. 5

SJO~: VI EWS O f" VA RIOUS F ORi\'IS OF EQUJPME."lT

Showing evolution of s traps in annpit

1908

195




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1937

1951 Experimental (Battle Order)

1942 Battlt: Jerkin 1944

1951 Experimental (Marching Order)

(Supporting strap through armpit rises in Marching Order)

FIG. 6 SIDE VrEWS OF VARIOUS FOR~lS OF EQUIP.\-lEKl'

Showing evolution of straps in armpit. Short arrows indicate armpit straps.




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E. T. Renbourn 197

sequent vasomotor shock which may be fatal. Of the conditions which may predispose to such an outcome, we have lack of food and sleep, climatic extremes, and poor morale. It was well known to Pringle in 1762 that marching with a load in a hot climate was conducive to death from heat stroke, but as a lesson this is still sometimes forgotten.

Although the disorders we have described are not common, they must be considered amongst the problems of the marching soldier. In the past, measurement of energy expenditure has been used in the classic experiments that have determined the maximum load and the best methods of carrying it. Such a technique has, however, at the best thrown light on the efficiency of muscle activity under short term and controlled laboratory conditions, and may not be a valid measure of the soldier's efficiency in carrying his load under the prolonged and variable stresses of the field. Furthermore, the technique may give no indication of the liability to the clinical disorders we have outlined above.

A.O.R.G. AND 1951 EXPERIMENTAL EQUIPMENT

As the outcome of the demands of the War Office Qualitative Requirement of 1950 for an improvement in personal load carriage equipment, research which had already commenced in A.O.R.G. was completed in the same year, and an excellent report produced by Lippold and Naylor (63). Working on the principle that the minimal disturbance of the centre of gravity of the body was desirable, an electromyographic technique was used to indicate activity in the back muscles when loads were carried in different ways. The results showed that more muscles are active with an unbalanced than with a balanced load, and that a long, narrow, flat pack produces less activity of the Trapezius and Sacrospinalis muscles than the high pack of the 1937 equipment. It was noted in the paper that "disproportional expenditure of energy does not necessarily mean disproportionate rate of fatigue." This would fit into the concept outlined above, that load carriage is more than a matter of muscle tone and contraction. As an outcome of the report, a new design of equipment was produced for Battle Order. In principle, this is a long, narrow, flat pack, balanced by ammunition pouches in front, and with the weight of the pack distributed between the shoulders and hips. Due to inverse relations of movements at the hip and shoulder joint during walking (64), a certain amount of bounce of the load is inevitable. Such a mode of load carriage, utilizing a long narrow pack, was already in use in Germany, Austria, Belgium and Denmark towards the end of the last century, and shoulder-hip carriage was the principle employed in the 1871 valise equipment. It will be remembered that Lavisse in 1902 strongly recommended a long, narrow, flat pack with shoulder-hip carriage. The present 1951 experimental web equipment (Z2 pattern) is based on the A.O.R.G. design.

KNAPSACKS AND FEET

During the Second Wodd War some interesting experiments were carried out in America by Turrell and Robinson (65) on the relationship of heavy boots




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to the energy requirements of the soldier. It was shown that the addition of one pound to the weight of shoes was equivalent in energy cost to the carriage of four pounds on the back. Recent unpublished work in this laboratory confirms the finding, but suggests that the ratio is nearer 1 : 2.5. The problem, however, is not a new one. Munson in 1901 (30) quoted a rash authority who stated that "one gramme on the shoe is equivalent to one kilogramme in the knapsack." Parkes in England, Morache in France, Roth and Lex in Germany, and Munson in America were all concerned with the importance to the soldier of rational footgear, and the effect of marching with loads on the arch of the foot, swelling -of the foot and frictional blisters.

As early as 1855, Breithaupt described in young soldiers a condition of chronic painful swollen feet (Fussgeschwulst), due to prolonged or forced marches When carrying full knapsacks. Stechow, surgeon to the Prussian Guard, first showed in 1897, with the aid of the recently introduced X-ray technique, that the condition was due to a "hair line" fracture of the metatarsal bones of the foot (66). The French Army Surgeons Chapotot and Boisson described the condition in 1899 as "Pied Force ... provoque par la marche des fantassins." During the First World War many cases of "March" or "Pack Fracture" of the foot were recorded, and before the Second World War a group of cases was published by Kiintscher (67) and attributed to the rapid and intensive training of young German recruits. During the last war the disorder had so increased in frequency that in 1946 six papers dealing with the subject were reviewed in the same journal (62). New boots should be tried on by men wearing full marching gear, but it is doubtful if this is often done.

CONCLUSIONS

Lothian, in his historical review (41), has shown the conflict in the minds of generals between the "Essentials" of a soldier's load and the "Necessaries" of his mobility. In the history of all armies there are numerous examples of overburdened soldiers discarding excess or uncomfortable equipment in order to survive and do battle; and other examples where they have collapsed by the roadside, shackled to the knapsack, too exhausted to fight, or to consolidate what they had gained. We have noted the attempt to free the British soldier during the Boer War, and the effect of overloading him during the First World War. Colonel Marshall (68), of the American Army, has recently reviewed in a trenchant manner the problems of the soldier's load, and quoted numerous examples from the Second World War of the dire consequences of overload. Since the time of Professor Parkes and the Committee of 1865-1868, the physiologist, and sometimes the soldier, has preached to the unheeding a lesson still not yet learned. A soldier converted into a beast of burden inevitably loses his intrinsic, but most prized, weapons-his morale, his initiative and his audacity. Only the commanders can put this lesson into practice.

We have shown that in the history of load carriage there have been many trials and tribulations, and it is sometimes to be wondered whether the soldier is in fact better off today than he was with the valise equipment in 1871. It is




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E. T. Renbourn 199

seen that there has been a great deal of repetition of earlier work due, often, to lack of knowledge of what had been done before. Although there have been great technical advances during the present century, the principles used today in load carriage were already well known long before the end of the nineteenth century. The acceptance of an equipment by one committee, and its rejection a few years later by another, recurs throughout the history we have traced. This is perhaps partly due to conclusions which were never valid; but also to the fact that a load carriage equipment, like all military equipment, should always have a drill for its correct usage. This may in fact be practised by the inventors, or by the soldiers, in the early days of its use; but in time such drill tends to become seriously neglected, or forgotten, particularly if it lacks simplicity.

The mode of equipment testing, by either laboratory experiments or field trials, is of great importance in the choice of the best tools for the fighting soldier. From the earliest days it has been an accepted fact that the opinion of an officer may not always be a good indication of the value of an equipment to the fighting soldier. Questionnaires have been used since the trials of 1865-1868 as a measure of the subjective effect on the user, but unless the questions are designed to eliminate bias, misleading information may be obtained. Furthermore, it may be impossible to draw sound conclusions', even from objective tests, however carefully carried out, unless the experiments are suitably designed and the data examined for statistical significance. Differences which are statistically significant may nevertheless be too small for practical consideration. The failure to appreciate the import of these various deliberations is found throughout almost the whole history of load carriage. As a result, much data has accumulated, but it is often difficult to draw valid conclusions.

It is with some dismay that one discovers that little is new; that physiological methods have been used for nearly a hundred years. However, the various techniques (pulse rate, stress and pack tests, body temperature, sweat loss and energy metabolism, electro-myography and so forth) indicate, at the best, the short term effects on some particular bodily functions; and they are not necessarily a valid measure of the efficiency of the whole man-the soldierin carrying out his varying and prolonged military duties. This is particularly true of experiments limited to the controlled environment of the laboratory. For this reason, performance tests, simulating military tasks, and carried out under the realities of the field, should be included among the various methods of investigation in order to give a more complete evaluation of the problem. The scientific team is incomplete without the close collaboration of Service officers, experienced in field trials and exercises.

In the clothing worn, the equipment they use, and the loads to be carried, soldiers are essentially uniform and standardized. But it is to be remembered that in height, weight, muscular efficiency and military fitness, soldiers are predominantly individuals. The effect of a load, or a particular load carrying equipment, hence varies appreciably from man to man; and in the same man,




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with climate and terrain, training and experience, with the state of morale. It must be accepted that the vertical frame of the human body is not adapted for the carriage of heavy loads, especially by men marching in step and in military formation. The physiologist must consider the requirements, plan the experiments, consider all the relevant data, and then advise; but the final decision will always have to come from the commanders in the field, who alone are intimately conversant with the soldier's function, and the purpose of his equipment. Hence the load carried by the soldier, and the personal load carriage equipment, will probably always be a compromise between what is physiologically sound and what is operationally essential.

ACKNOWLEDGMENTS

Thanks are due to Mr. D. W. King of the War Office Library for valuable help in the search for relevant War Office Confidential· Papers, for numerous references and for some of the figures; to Mr. A. A. Lethern of the Mills Equipment Company for information on the early history of web equipment; to A.M.D.S, the War Office, for permission to examine files dealing with load carriage.

This paper is published with the permission of the Chief Scientist, Ministry of Supply.

REFERENCES (59) ROGERS, L. (1949). Brit. Med. J., 2, 956. (60) STAMMERS, F. A. R. (1950). Lancet, 1, 603. (61) FLOYD, W. F., and SILVER, P. H. S. (1951). Lancet, 1, 133. (62) Various authors (1946). War Medicine, 6, 47,109,257,328 and 398. (63) LIPPOLD, O. C. J., and NAYLOR, P. F. D. (1950). The Design of Load Carriage

Equipment for the Soldier in Battle Order. A.O.R.G. Report, 11/50. (64) STEINDLER, A. (1935). Mechanics of Normal and Pathological Locomotion in Man.

London. (65) TURRELL, E. S., and ROBINSON, S. (1943). Interim Report to C.M.R., No. 3. (66) STECHOW (1897). Deutsche Mil.-iirtzl. Ztschr., 26, 465. (67) KUNTSCHER, G. (1939). Med. Klin., 35, 973. (68) MARSHALL, COLONEL S. L. A. (1950). The Soldier's Load and the Mobility of a

Nation. Washington.

GENERAL REFERENCES (1) RAVENEZ, E. F. (1817). L'habillement actuel du Soldat. Paris. (2) HARDINGE, COLONEL H. (1828-1844). Regulations for the Provision of Clothing,

Necessaries, Accoutrements, and Appointmentsfor Corps of Infantry. H.M.S.O. London.

(3) LUARD, COLONEL J. (1857). History of the Dress of the British Soldier. London. (4) KRAUS, O. A. (1907). Bekleidung und Ausriistung der Irifanterie. Berlin. (5) FORBES, MAJOR-GENERAL A. (1929). A History of the Army Ordnance Service.

London . . (6) LAWSON, C. C. P. (1940). A History of the Uniforms of the British Army. London. (7) GESSLER, E. A., and SCHNEIDER, H. (1952). "Uniforms." Ciba Review No. 93.

Basle.




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