HUMAN
F A C T O R S , 1975, 17(4),328-336
Biornechanical Analysis of the U.S. Navy Mark V and Mark XI1 Diving Systems ARTHUR J. BACHRACH, Behavioral Sciences Departttietit, Naval Medical Research Iiistittite, Betliesda, Marylaiid; GLEN H . EGSTROM, Perfoniiaiice Physiology Laboratory, Uiiiversity of California at Los Aiigeles; atid SUSAN M . BLACKMUN,.Beliavioral Scieiices Department, Naval Medical Research Institute, Betliesda, Marylaiid
This stitdy is oiie of a series of litiriratt factors atialyses coittpariiig two US.Navy siirfacesiipported Iiardliat diviiig systetiis - the standard Mark V and the prototype Mark XII. The study assessed the range of motion iti the two divirigsystenis, tisitig a bionieclianical analysis. Foiirteeti aiitliropometric iiieastirenieiits were chosen wliicli represented gross body moveitietits used iii hardhat diviiig arid likely t o be affected most b y diviiig suits. After ttieastiritig each moveinelit, coiiiparisotis were made with s w i m suit baselities to deteniiiiie lioiv i ~ i ~ c l i loss of ttiobility had occurred. The MarkXII ivassiiperior to the Mark V overall, both in wet arid dry modes.
INTRODUCTION
the interest of’increased safety and efficiency underwater. The typical working diver, enIn the development of diving technology, closed in a cumbersome copper hardhat and little systematic human engineering has been done. The diver is often expected to compen- canvas diving dress, is protected but loses sate for inadequacies in equipment design. mobility, reminding us of Robert Browning’s This is not only true in commercial and Navy phrase (from Herakles) that “ A man in armour diving, but in sport diving as well. Consider- is his armour’s slave”. The present study’ is one of a series comparing the level of sophistication in such areas as ing the U S . Navy diving system, the Mark V, vision research, the observation by Egstrom with a newly developed prototype, the U.S. (1970) is interesting: “. . . faceplates have reNavy Mark XI1 (Figures 1 and 2 ) . The goal of mained virtually unchanged since the 30’s and was to compare the flexibility of the this study few major problems have been resolved. The two diving systems, using a biornechanical faceplate still provides tunnel vision, magnifianalysis. cation, refraction, and in some cases, distorThe background of the biomechanical techtion. The sports diver adapts to these limitanique is derived from anthropornetric meastions and generally finds little fault with faceplates. However, the increasing demands on ures. Static anthropometry deals with dimenworking divers should result in a closer look at sions and, in the applied situation, is concerned with the range of size for design of such the problem.” Similar comments may be made regarding Other studies in process dealing with human tanks, regulators, and other gear. For the factors include work-physiology measures. Kinney, working diver, as Egstrom suggests, human Luria, Ferris, and Paulson (1972) compared visual factors must be more carefully considered in acuity and related factors.
328
August, 1975-329
ARTHUR J. BACHRACH AND OTHERS
Figure 1 . US. Navy hfark V siirface-siippofled liardhat divirzg systern.
aspects as clothes and work space. Static anthropometric measures have been accomplished previously with a U.S. Navy diverpopulation (Beatty and Berghage, 1972). Dynamic anthropometry deals with functional measurements and is concerned with the quantitative measurement of joint angle changes and range of motion while people are performing volitional movements. The techniques of dynamic anthropometry were employed in this study.
Figure 2. US. Navy Mark XI1 prototype siirfaceslipported hardhat divirzg system.
Measiireriteiit Metliodology
In biomechanical measurement the problem of standardizing positions and reference marks exists. Accordingly, positions and reference points that seemed most appropriate to yielding data on the comparative flexibility of each diving system were chosen. The areas of the body selected for measureMETHOD ment were based on a rationale of joint Siibjects movement as described by Hertzberg (1 972): Six male, professional, Navy-trained divers “the movable joints of the body articulated by served as subjects. They ranged in height from means of ligaments (tough, fibrous bands)” 66 to 75 in. (167.6 to 190.5 cm), in weight from are of several types, of which the three most 145 to2351b(65.8 to 106.6kg),andinagefrom important are (1) hinged joints (finger); (2) pivot joints (elbow); and (3) ball and socket 29 to 40 years (Table 1).
330-August, 1975
HUMAN FACTORS
TABLE 1 Subjects: Physical Characteristics
Subject
1 2 3 4 5 6
Height (in.) (m)
67.5 72.0 68.0 70.5 66.0 75.0
1.71 1.83 1.73 1.79 1.68 1.91
Mean
9.0 69.8
.229 1.77
First-class diver population: means
69.4
1.76
Range
Percentile,
21 87 28 68 8 99
52
Weight (lb) (kg)
Percentile
Age (yr)
40 32 32 31 29 29
175 196 185 145 148 235
79.4 88.9 83.9 65.8 67.1 106.6
42 75 59 9 10 99
90 181
40.8 82.1
-
180
81.6
~
49
11 32
’ Percentiles extrapolated from data presented in Beally and Berghage (1972) joints (shoulder and hip).The range of motion, Hertzberg notes, is limited by the joint body configuration, by the attached muscles, tendons, and ligaments, as well as by the amount of surrounding fatty tissue. All of these vary from person to person and within individuals from time to time. He also notes that “joint movement is measured a t the angle formed by the long axes of two adjoining body segments (link lines) or, in some cases, of the angle formed by one body segment and a vertical or horizontal plane. The total range of movement is measured between the two extreme positions of the joint.” A further guideline for measurement comes from the observations of Dempster (1955) that “all movements are rotational” rather than linear, and are measured in degrees or radians. He also notes that “ligaments, bony stops (elbow), tissue bulk (knee flexion), or muscle stretch define limits to the range of movement”. Functional ranges are, of course, also based on individual structure. The types of movement described are limited by internal mechanical stops. In a comparison of diving dress, the analysis must begin with a measurement of the individual,
undressed, for optimal measurement of these internal mechanical stops. When the diver is suited up in diving dress, the imposed external mechanical limitations of the gear itself can then provide a basis for range-of-movement analysis. As far as was possible, the measures in the study were taken along mechanical axes using bony landmarks as reference points.
Procedt rre Each subject served as his own control with his baseline measurements taken in a swim suit before any gear was donned. Subjects were then measured while wearing the Mark V and Mark XU. both on dry land and in the water. To minimize error, each movement was measured three times, with the mean used as the recorded figure. Measurements in the two suits were never taken consecutively, because subjects were usually fatigued after one suit had been worn. Air was used as the breathing medium during all measuring sessions. Fourteen separate range-of-motion measurements were chosen (Figure 3), representing gross body movements principally used in hard-
ARTHUR J . BACHRACH AND OTHERS
August, 1975-33 1
Figure 3. Schemalic diagrann of Ihe 14 anrhroponierric
hat diving and likely to be affected most by diving suits was calculated in relation to the the diving suits. The subjects were told to exe- swim suit baselines (Table 3). The impairment cute each movement through the fullest pos- in degrees was converted into percentages for sible range of motion but without extremely easy comparison across diving systems and forceful straining. The following general types measurements. Pair t tests were performed on of movement were measured: flexion (rcduc- the measurements to determine whether the ing joint angle); extension (increasing a joint flexibility of the two suits differed signifiangle); abduction (movement away from the cantly (Table 4). body midline); and rotation (turning or twistIn the dry mode, the Mark XI1 was signifiing). The following joints were used: shoulder, cantly more flexible for 8 of the 14 movements: elbow, hip, knee, and trunk. trunk extension, trunk lateral flexion, shoulRange of joint movement was measured in der joint abduction, shoulder joint flexion, degrees with a 12-in. (30.5 cm) plastic com- shoulder joint extension, shoulder joint horipass with metal rods attached to extend the zontal flexion, knee flexion, and hip abduccompass arm length by 2 ft. (0.6 m). The com- tion. pass was used for all measurements. For In the water, the Mark XI1 allowed greater transerve rotation of the trunk, an indicator flexibility for 6 of the 14 movements: trunk rod attached to a fixed metal cup was also extension, shoulder joint abduction, shoulder used. Table 2 lists procedures for the 14 an- joint flexion, shoulder joint horizontal flexion, thropometric movements. knee flexion, and hip abduction. Averaging all measurements taken in the RESULTS AND DISCUSSION water. the Mark XI1 allowed meaterflexibilitv After measuringeach movement in degrees, (p < .005). Combing wet and dry data for all loss of flexibility in the Mark V and Mark XI1 measurements, the Mark XI1 was less restrictY
332-August, 1975
HUMAN F A C T O R S
TABLE 2
Procedures for 14 Anthropomctric hleasures' Movement
Position of Bodv
Procedure
1. Trunk flexion
Feet together. Knees locked. Trunk bent forward at the waist. Shoulders rounded. Trunk flexed from standing position.
Compass placed on centerof rotation of hip joint, one rod extended down the center of lateral malleolusat ankle; theother rod placed on centerof rotation of shoulder joint. Difference in compass readings recorded.
2. Trunk extension
Feet together. Same reference points as above, except upper Knees locked. pointer rod placed on posterior junction of upper Trunk hyperextended from arm and shoulder. waist.
3.Trunk lateral flexion
Feet together. Compass placed on lower spine, one rod in a Knees locked. vertical line between the buttocks, the other on Hips stationary while bending the cervical spine at the neck. trunk to the side.
4. Trunk
Normal upright position. Trunk and shoulders twisted to each side. Hips held in starting position and not twisted.
Cup attached to indicator rod was placed on bony junction of shoulder girdle and shoulder joint (acromion process), with a suspended weight hanging to the ground. Floor was marked under weight, and also at the pivot point of the feet, directly between the medial malleolus of the ankle. When subject twisted trunkand shoulders to each side (holding hips in starting position), the points of maximum movement were marked on the floor under the weight. The compass was then used to measure the angles formed by the marks on the floor.
5. Shoulder joint abduction
Normal upright position. Arm raised out to side and up, palm up, elbow locked. (Shoulder joint outward rotated to permit arm to be raised over head).
Center of compass placed on center of rotation of scapula, one rod on tip of ulna at wrist, the other compass arm pointed perpendicular to floor.
6. Shoulder joint flexion
Normal upright position. Center of compass placed on center of head of Arm raised forward, palm humerus at shoulder joint, one rod on tip of ulna down and elbow locked. at wrist; other compass arm held vertical, down side of body.
7. Shoulder joint extension
Normal upright position. Compass placed on same points as for shoulder Arm raised to rear, palm facing joint flexion. back, elbow locked.
8. Shoulder joint horizontal flexion
Normal upright position. Shoulder joint abducted to90". Arm moved forward at horizontal plane, palm down, elbow locked.
9. Shoulder joint horizontal extension
Normal upright position. Compass placed on same points as for shoulder Shoulder joint abducted to 90". horizontal flexion. Arm moved backward in horizontal plane, palm down, elbow locked.
transverse
rotation
Center of compass placed on top of acromion process (shoulder abducted to go"), both rodson tip of ulna at wrist. One rod was held stationary, the other moved with the arm.
August, 1975-333
ARTHUR J . BACHRACH AND OTHERS
10. Elbow flexion
Normal upright position.
11 Knee flexion
Normal upright position. Center of compass placed on lateral center of Lower leg raised to rear to flex rotation of knee joint, rods extended to center of knee. head of femur at hip joint and center of lateral malleolus at ankle.
12. Hip flexion
Normal upright position. Back straight. Thigh raised toward chest, knee bent.
Centerof compass placed on center of rotation at hip joint with one rod extended up trunk to center of acromion process at shoulder joint, other running along thigh to knee.
13. Hip extension
Normal upright position. Knee locked. Leg extended to rear.
Same compass points as in hip flexion.
14. Hip abduction
Normal upright position. Trunk vertical. Knee locked. Leg abducted.
Center of compass placed over center of anterior aspect of hip joint, one rod along a vertical axis and the other along inside of leg to center of medial malleolus at ankle.
~
Center of compass placed on lateral center of rotation of elbow joint with rods extended to tip of ulna at wrist and center of acromion process at shoulder joint.
' Shown in Figure 3. TABLE 3 Range of hlotion (degrees) for the hiark V and hlark XI1 Diving Suits Dry Movement Trunk flexion Range Mean
Swim Suit Mark
Wet
V Mark XI1 Mark V Mark XI1
106-1 30 116.4 7.5
92-114 103.3 7.7
88-115 103.4 10.3
Trunk extension Range Mean S.D.
49-70 58.8 8.0
31-58 43.3 10.1
48-65 29-36 54.7 . 34.4 6.0 2.6
33-54 42.8 6.7
Trunk lateral flexion Range Mean S.D.
27-34 30.8 2.6
15-33 22.7 6.1
20-34 27.3 5.1
17-29 21.8 4.2
18-28 21.4 3.5
Trunk transverse rotation Range Mean S.D.
38-62 53.0 9.1
23-37 30.3 4.5
22-46 32.8 7.7
31-41 36.3 3.5
25-44 36.0 7.9
S.D.'
Shoulder joint abduction Range Mean
S.D. Shoulder joint flexion Range Mean
S.D.
177-1 91 182.0 6.2
I
6 ~ 9 5 67-114 83.1 84.9 9.9 15.3
100-123 111-161 114-130 142-155 142.1 116.8 149.9 108.5 8.0 4.4 8.2 15.1
16 ~ 9 0 85-114 g a l 6 1 97.5 136.2 179.4 20.6 10.5 8.6
95-121 139-166 108.9 150.4 9.1 10.1
H U M A N FACTORS
334-Augu~t, 1975
Shoulder joint extension Range Mean S.D.
34-59 45.7 7.7
42-63 51.7 6.3
46-69 56.4 7.1
44-69 56.4 8.0
6.9
66-93 82.0 9.4
84-106 99.0 7.7
68-87 79.3 7.0
91-115 100.8 8.2
4E-62 51.4 5.4
27-47 33.8 6.5
27-46 36.2 5.7
24-58 39.7 10.8
28-50 38.8 8.3
59-75 64.7 5.9
Shoulder joint hor. flexion Range 119-140 Mean 129.9 S.D.
Shoulder joint hor. ext. Range Mean S.D.
Elbow flexion Range Mean S.D.
Knee flexion ange Mean S.D.
Hip flexion Range Mean S.D.
Hip extension Range Mean S.D.
Hip abduction Range Mean S.D.
140-152 125143 126-139 129-140 135-141 138.6 133.8 137.0 135.0 146.6 4.0 2.1 6.3 3.9 3.6 90-107 102-126 100.2 112.2 5.3 7.4
109-1 36 122.1 8.3
85-97 91.4 4.2
97-115 108.5
87-1 11 103.5 8.7
57-77 66.1 5.9
58-79 69.4 7.2
72-83 77.1 3.7
57-92 78.1 11.1
29-40 34.3 3.8
11-27 18.4 5.1
17-37 24.1 6.4
16-25 19.0 2.9
9-40 24.2 9.4
39-65 52.4 8.7
18-28 22.1 3.1
2339 29.8 5.8
25-35 30.4 2.8
26-51 40.6 8.5
5.9
Standard deviation
ive (p c .01). In no case was the Mark V superior to the Mark XII, either wet or dry. The results of each range-of-movement measurement are as follows: (1) Trunk flexion. No significant differences were found between the two suits; however, this movement is more difficult to perform in both suits in the water than on dry land. In the dry mode, the weight of the helmet 'helps to pull the trunk forward; in the water, the positive buoyancy of the Mark XI1 helmet somewhat hinders downward motion. (2) Trunk extension. The Mark XI1 allowed more flexibility in the water (p < .05). and for
the combined wet and dry data (p < .01). This movement is also difficult to perform in the water, being affected by the same factors as in trunk flexion, but to a lesser degree. (3) Trunk lateral flexion. The Mark XI1 was significantly more flexible in the dry mode only (p < .05).Buoyancy was aslight problem. (4) Trunk transverse rotation. There were no significant differences. Some restrictions of this movement were caused by suit materials, gas volumes, etc., but were equally limiting in both suits. (5) Shoulder joint abduction. In the water, the Mark XI1 allowed more movement for this
August, 1975-335
ARTHUR J. BACHRACH AND OTHERS
TABLE 4
Mean Percentage Loss of Diver FlexibilityCaused by the Mark V and Mark XI1 Diving Suits Movement
Trunk flexion Trunk extension Trunk lateral flexion Trunk transverse rotation
Shoulder joint abduction Shoulder joint flexion Shoulder joint extension Shoulderjointhor.flexion Shoulder joint hor. extension Elbow flexion Knee flexion Hip flexion Hip extension Hip abduction Overall mean loss Difference
Dry Mark V Mark VII 11.1 26.9 27.2 42.2 40.4 47.5 29.8 37.0
11.2 12.5 12.3 37.8 22.1 24.1 20.2 23.7
34.6 7.9 24.8 35.6 46.7 56.8
29.6 8.7 11.1 32.9 30.0 42.4 22.7
33.3 10.6
p
ns .05 .05
ns .01 .01
.05 .01
ns ns .01
ns ns .05
Wet Mark V Mark XI1 28.5 38.1 29.9 29.5 35.9 39.3 12.9 39.0
26.9 26.8 31.0 31.3 17.6 16.1 13.0 22.0
23.2 6.4 17.7 25.1 43.8 40.8 29.3
24.9 5.4 8.0 24.8 31.0 21.1 21.4
p
ns .05
ns ns .01 .01
ns .01
ns ns .01 ns
ns .01
7.9
p = level of significance ns = not significant
important motion of the arm (p < .Ol). In the data showed no significant differences beMark V, it was difficult to raise the arm much tween the two suits. beyond a horizontal plane, owing to interfer(1 0) Elbow flexion. No significant difference from the breastplate, which makes over- ences were found between the two suits. Suit head movements exceptionally difficult. if not materials and air within the sleeves caused impossible. slight restrictions (an average of 7% impair(6) Shoulderjoint flexion.This motion of the ment compared with swim suit flexibility). arm, similar to shoulderjoint abduction, is an This is the only movement that showed little important one for overhead work and was dif- or no restriction in either suit. ficult to perform in the Mark V. The Mark XI1 (1 1) Knee flexion. There was more flexibility was more flexible in all cases (p < .01). (p < .Ol) in the Mark XII, probably a result of (7) Shoulder joint extension. No statistically the difference in weight of the boots (a Mark V significant differences were found in the boot weighs 17.5 Ibs [7.9 kg], and a Mark XI1 water, but on land the Mark XI1 allowed more boot weighs 10 lbs [4.5 kg]). This opinion is freedom of movement. further supported by the fact that the range of (8) Shoulder joint horizontal flexion. motion in the Mark V increases in the water Movement was hampered by the bulky mate- where the boot weight has less effect than on rials of the two suits and by the gas volumes land. within thesuits.The breastplate in the MarkV (12) Hip flexion. There were no significant makes i t difficult to bring the arm straight differences between the two suits, either wet forward. For this particular motion, the Mark or dry, but both were better in the water than XI1 was significantly less restrictive (p < .01). on dry land, where interference from heavy (9) Shoulder joint horizontal extension. The boots was greater.
-
336-August, 1975
(13)Hip extension.The MarkXII was better, but only when both wet and dry data were combined. This motion was difficult to measure accurately since even the baseline angle was small (around 30"). All the subjects had trouble performing it correctly in the water. (14) Hip abduction. The Mark XI1 was significantly superior, again probably a result of lesser boot weight. This ,movement (keeping the body vertical while lifting the leg and heavy boot out to the side) is particularly awkward and physically difficult in the dry mode. Five of the six subjects considered themselves too light in the Mark XI1 to adequately perform the trunk movements (trunk flexion, extension, and lateral flexion). Under actual working conditions weight would be adjusted, but to maintain consistency in this phase of testing, each suit was worn as designed, with the standard amounts Of weight.1t is possible that, with added weight, the Mark XI1 could
show greater trunk in the water. The one diver who had no complaints about his \,,eight had only 1% impairment of flexion in the water. The others found it difficult to keep their feet on the bottomwhile pulling against the buoyancy of the helmet. Individual differences in ment were apparent in all of the k g movemerits, particularly on land, where boot weight has a greater effect.
HUMAN F A C T O R S
The overall mean loss of mobility in the water was 21.4% for the Mark XII, and 29.3% for the Mark V, a difference of 7.9%. The results of this study indicate the Mark XI1 was clearly superior overall to the Mark V in both wet and dry modes. ACKNOWLEDGMENTS This research was funded by the Bureau of hledicine and Surgery, Navy Department, Research Su b t ask h14306.03.204DAC9. The opinions and statements contained herein are the private ones of the writers and are not tobeconstruedasofficialorreflecting theviewsoftheNavy Department or the naval service at large. The authors wish to thank F. W. Armstrong, the late K. J. Conda. and J. M.Woolley, Behavioral Sciences Department of the Naval Medical Research Institute, whoactedas subjects and provided technical assistance. We would also like to thank divers R. I. Ault and R. Radecki, of the U S . Navy Experimental Diving Unit, and W. E. Long. Jr., Environmental Biosciences Department of the Naval Medical Research Institute, for acting as subjects. The authors also wish to thank LT D. R. Chandler, MSC. USN, of the U S . Navy Experimental Diving Unit, for his encouragement and support.
REFERENCES Beatty. H.T. and Berghage. T. E. Diver anthropometrics. Washingt0n.D.C.: U.S.NavyExperimenta1DivingUnit Research Report 10-72. June, 1912. Dempster,W. T.Theanthropometryofbody action.Attrtafs o f t h e N e w YorkAcadeniyofSciertces, 1955.63.559-585. Egstr0m.G. H. Effect ofequipment on divingperformance. In Hro~zatzperfonnorice in scuba diving. Chicago: The Athletic Institute, 1970,516. Hertzberg. H. T. E. Engineering anthropology. In H. Van Cott and R. G. Kinkade (Ed.) Human engirweririggitide to eqtcipnzetifdesigti. Washington, D.C.: Superintendent of Documents. 1912. Kinney. J. S., Luria, S . M.,Ferris. S. H., andPau1son.H. hl. Optical andvisual testson the Navyprototypehardhat diving system. Groton. Connecticut: US. Naval Submarine Medical Research Laboratory. Report 73 1, 1972.
F A C T O R S , 1975, 17(4),328-336
Biornechanical Analysis of the U.S. Navy Mark V and Mark XI1 Diving Systems ARTHUR J. BACHRACH, Behavioral Sciences Departttietit, Naval Medical Research Iiistittite, Betliesda, Marylaiid; GLEN H . EGSTROM, Perfoniiaiice Physiology Laboratory, Uiiiversity of California at Los Aiigeles; atid SUSAN M . BLACKMUN,.Beliavioral Scieiices Department, Naval Medical Research Institute, Betliesda, Marylaiid
This stitdy is oiie of a series of litiriratt factors atialyses coittpariiig two US.Navy siirfacesiipported Iiardliat diviiig systetiis - the standard Mark V and the prototype Mark XII. The study assessed the range of motion iti the two divirigsystenis, tisitig a bionieclianical analysis. Foiirteeti aiitliropometric iiieastirenieiits were chosen wliicli represented gross body moveitietits used iii hardhat diviiig arid likely t o be affected most b y diviiig suits. After ttieastiritig each moveinelit, coiiiparisotis were made with s w i m suit baselities to deteniiiiie lioiv i ~ i ~ c l i loss of ttiobility had occurred. The MarkXII ivassiiperior to the Mark V overall, both in wet arid dry modes.
INTRODUCTION
the interest of’increased safety and efficiency underwater. The typical working diver, enIn the development of diving technology, closed in a cumbersome copper hardhat and little systematic human engineering has been done. The diver is often expected to compen- canvas diving dress, is protected but loses sate for inadequacies in equipment design. mobility, reminding us of Robert Browning’s This is not only true in commercial and Navy phrase (from Herakles) that “ A man in armour diving, but in sport diving as well. Consider- is his armour’s slave”. The present study’ is one of a series comparing the level of sophistication in such areas as ing the U S . Navy diving system, the Mark V, vision research, the observation by Egstrom with a newly developed prototype, the U.S. (1970) is interesting: “. . . faceplates have reNavy Mark XI1 (Figures 1 and 2 ) . The goal of mained virtually unchanged since the 30’s and was to compare the flexibility of the this study few major problems have been resolved. The two diving systems, using a biornechanical faceplate still provides tunnel vision, magnifianalysis. cation, refraction, and in some cases, distorThe background of the biomechanical techtion. The sports diver adapts to these limitanique is derived from anthropornetric meastions and generally finds little fault with faceplates. However, the increasing demands on ures. Static anthropometry deals with dimenworking divers should result in a closer look at sions and, in the applied situation, is concerned with the range of size for design of such the problem.” Similar comments may be made regarding Other studies in process dealing with human tanks, regulators, and other gear. For the factors include work-physiology measures. Kinney, working diver, as Egstrom suggests, human Luria, Ferris, and Paulson (1972) compared visual factors must be more carefully considered in acuity and related factors.
328
August, 1975-329
ARTHUR J. BACHRACH AND OTHERS
Figure 1 . US. Navy hfark V siirface-siippofled liardhat divirzg systern.
aspects as clothes and work space. Static anthropometric measures have been accomplished previously with a U.S. Navy diverpopulation (Beatty and Berghage, 1972). Dynamic anthropometry deals with functional measurements and is concerned with the quantitative measurement of joint angle changes and range of motion while people are performing volitional movements. The techniques of dynamic anthropometry were employed in this study.
Figure 2. US. Navy Mark XI1 prototype siirfaceslipported hardhat divirzg system.
Measiireriteiit Metliodology
In biomechanical measurement the problem of standardizing positions and reference marks exists. Accordingly, positions and reference points that seemed most appropriate to yielding data on the comparative flexibility of each diving system were chosen. The areas of the body selected for measureMETHOD ment were based on a rationale of joint Siibjects movement as described by Hertzberg (1 972): Six male, professional, Navy-trained divers “the movable joints of the body articulated by served as subjects. They ranged in height from means of ligaments (tough, fibrous bands)” 66 to 75 in. (167.6 to 190.5 cm), in weight from are of several types, of which the three most 145 to2351b(65.8 to 106.6kg),andinagefrom important are (1) hinged joints (finger); (2) pivot joints (elbow); and (3) ball and socket 29 to 40 years (Table 1).
330-August, 1975
HUMAN FACTORS
TABLE 1 Subjects: Physical Characteristics
Subject
1 2 3 4 5 6
Height (in.) (m)
67.5 72.0 68.0 70.5 66.0 75.0
1.71 1.83 1.73 1.79 1.68 1.91
Mean
9.0 69.8
.229 1.77
First-class diver population: means
69.4
1.76
Range
Percentile,
21 87 28 68 8 99
52
Weight (lb) (kg)
Percentile
Age (yr)
40 32 32 31 29 29
175 196 185 145 148 235
79.4 88.9 83.9 65.8 67.1 106.6
42 75 59 9 10 99
90 181
40.8 82.1
-
180
81.6
~
49
11 32
’ Percentiles extrapolated from data presented in Beally and Berghage (1972) joints (shoulder and hip).The range of motion, Hertzberg notes, is limited by the joint body configuration, by the attached muscles, tendons, and ligaments, as well as by the amount of surrounding fatty tissue. All of these vary from person to person and within individuals from time to time. He also notes that “joint movement is measured a t the angle formed by the long axes of two adjoining body segments (link lines) or, in some cases, of the angle formed by one body segment and a vertical or horizontal plane. The total range of movement is measured between the two extreme positions of the joint.” A further guideline for measurement comes from the observations of Dempster (1955) that “all movements are rotational” rather than linear, and are measured in degrees or radians. He also notes that “ligaments, bony stops (elbow), tissue bulk (knee flexion), or muscle stretch define limits to the range of movement”. Functional ranges are, of course, also based on individual structure. The types of movement described are limited by internal mechanical stops. In a comparison of diving dress, the analysis must begin with a measurement of the individual,
undressed, for optimal measurement of these internal mechanical stops. When the diver is suited up in diving dress, the imposed external mechanical limitations of the gear itself can then provide a basis for range-of-movement analysis. As far as was possible, the measures in the study were taken along mechanical axes using bony landmarks as reference points.
Procedt rre Each subject served as his own control with his baseline measurements taken in a swim suit before any gear was donned. Subjects were then measured while wearing the Mark V and Mark XU. both on dry land and in the water. To minimize error, each movement was measured three times, with the mean used as the recorded figure. Measurements in the two suits were never taken consecutively, because subjects were usually fatigued after one suit had been worn. Air was used as the breathing medium during all measuring sessions. Fourteen separate range-of-motion measurements were chosen (Figure 3), representing gross body movements principally used in hard-
ARTHUR J . BACHRACH AND OTHERS
August, 1975-33 1
Figure 3. Schemalic diagrann of Ihe 14 anrhroponierric
hat diving and likely to be affected most by diving suits was calculated in relation to the the diving suits. The subjects were told to exe- swim suit baselines (Table 3). The impairment cute each movement through the fullest pos- in degrees was converted into percentages for sible range of motion but without extremely easy comparison across diving systems and forceful straining. The following general types measurements. Pair t tests were performed on of movement were measured: flexion (rcduc- the measurements to determine whether the ing joint angle); extension (increasing a joint flexibility of the two suits differed signifiangle); abduction (movement away from the cantly (Table 4). body midline); and rotation (turning or twistIn the dry mode, the Mark XI1 was signifiing). The following joints were used: shoulder, cantly more flexible for 8 of the 14 movements: elbow, hip, knee, and trunk. trunk extension, trunk lateral flexion, shoulRange of joint movement was measured in der joint abduction, shoulder joint flexion, degrees with a 12-in. (30.5 cm) plastic com- shoulder joint extension, shoulder joint horipass with metal rods attached to extend the zontal flexion, knee flexion, and hip abduccompass arm length by 2 ft. (0.6 m). The com- tion. pass was used for all measurements. For In the water, the Mark XI1 allowed greater transerve rotation of the trunk, an indicator flexibility for 6 of the 14 movements: trunk rod attached to a fixed metal cup was also extension, shoulder joint abduction, shoulder used. Table 2 lists procedures for the 14 an- joint flexion, shoulder joint horizontal flexion, thropometric movements. knee flexion, and hip abduction. Averaging all measurements taken in the RESULTS AND DISCUSSION water. the Mark XI1 allowed meaterflexibilitv After measuringeach movement in degrees, (p < .005). Combing wet and dry data for all loss of flexibility in the Mark V and Mark XI1 measurements, the Mark XI1 was less restrictY
332-August, 1975
HUMAN F A C T O R S
TABLE 2
Procedures for 14 Anthropomctric hleasures' Movement
Position of Bodv
Procedure
1. Trunk flexion
Feet together. Knees locked. Trunk bent forward at the waist. Shoulders rounded. Trunk flexed from standing position.
Compass placed on centerof rotation of hip joint, one rod extended down the center of lateral malleolusat ankle; theother rod placed on centerof rotation of shoulder joint. Difference in compass readings recorded.
2. Trunk extension
Feet together. Same reference points as above, except upper Knees locked. pointer rod placed on posterior junction of upper Trunk hyperextended from arm and shoulder. waist.
3.Trunk lateral flexion
Feet together. Compass placed on lower spine, one rod in a Knees locked. vertical line between the buttocks, the other on Hips stationary while bending the cervical spine at the neck. trunk to the side.
4. Trunk
Normal upright position. Trunk and shoulders twisted to each side. Hips held in starting position and not twisted.
Cup attached to indicator rod was placed on bony junction of shoulder girdle and shoulder joint (acromion process), with a suspended weight hanging to the ground. Floor was marked under weight, and also at the pivot point of the feet, directly between the medial malleolus of the ankle. When subject twisted trunkand shoulders to each side (holding hips in starting position), the points of maximum movement were marked on the floor under the weight. The compass was then used to measure the angles formed by the marks on the floor.
5. Shoulder joint abduction
Normal upright position. Arm raised out to side and up, palm up, elbow locked. (Shoulder joint outward rotated to permit arm to be raised over head).
Center of compass placed on center of rotation of scapula, one rod on tip of ulna at wrist, the other compass arm pointed perpendicular to floor.
6. Shoulder joint flexion
Normal upright position. Center of compass placed on center of head of Arm raised forward, palm humerus at shoulder joint, one rod on tip of ulna down and elbow locked. at wrist; other compass arm held vertical, down side of body.
7. Shoulder joint extension
Normal upright position. Compass placed on same points as for shoulder Arm raised to rear, palm facing joint flexion. back, elbow locked.
8. Shoulder joint horizontal flexion
Normal upright position. Shoulder joint abducted to90". Arm moved forward at horizontal plane, palm down, elbow locked.
9. Shoulder joint horizontal extension
Normal upright position. Compass placed on same points as for shoulder Shoulder joint abducted to 90". horizontal flexion. Arm moved backward in horizontal plane, palm down, elbow locked.
transverse
rotation
Center of compass placed on top of acromion process (shoulder abducted to go"), both rodson tip of ulna at wrist. One rod was held stationary, the other moved with the arm.
August, 1975-333
ARTHUR J . BACHRACH AND OTHERS
10. Elbow flexion
Normal upright position.
11 Knee flexion
Normal upright position. Center of compass placed on lateral center of Lower leg raised to rear to flex rotation of knee joint, rods extended to center of knee. head of femur at hip joint and center of lateral malleolus at ankle.
12. Hip flexion
Normal upright position. Back straight. Thigh raised toward chest, knee bent.
Centerof compass placed on center of rotation at hip joint with one rod extended up trunk to center of acromion process at shoulder joint, other running along thigh to knee.
13. Hip extension
Normal upright position. Knee locked. Leg extended to rear.
Same compass points as in hip flexion.
14. Hip abduction
Normal upright position. Trunk vertical. Knee locked. Leg abducted.
Center of compass placed over center of anterior aspect of hip joint, one rod along a vertical axis and the other along inside of leg to center of medial malleolus at ankle.
~
Center of compass placed on lateral center of rotation of elbow joint with rods extended to tip of ulna at wrist and center of acromion process at shoulder joint.
' Shown in Figure 3. TABLE 3 Range of hlotion (degrees) for the hiark V and hlark XI1 Diving Suits Dry Movement Trunk flexion Range Mean
Swim Suit Mark
Wet
V Mark XI1 Mark V Mark XI1
106-1 30 116.4 7.5
92-114 103.3 7.7
88-115 103.4 10.3
Trunk extension Range Mean S.D.
49-70 58.8 8.0
31-58 43.3 10.1
48-65 29-36 54.7 . 34.4 6.0 2.6
33-54 42.8 6.7
Trunk lateral flexion Range Mean S.D.
27-34 30.8 2.6
15-33 22.7 6.1
20-34 27.3 5.1
17-29 21.8 4.2
18-28 21.4 3.5
Trunk transverse rotation Range Mean S.D.
38-62 53.0 9.1
23-37 30.3 4.5
22-46 32.8 7.7
31-41 36.3 3.5
25-44 36.0 7.9
S.D.'
Shoulder joint abduction Range Mean
S.D. Shoulder joint flexion Range Mean
S.D.
177-1 91 182.0 6.2
I
6 ~ 9 5 67-114 83.1 84.9 9.9 15.3
100-123 111-161 114-130 142-155 142.1 116.8 149.9 108.5 8.0 4.4 8.2 15.1
16 ~ 9 0 85-114 g a l 6 1 97.5 136.2 179.4 20.6 10.5 8.6
95-121 139-166 108.9 150.4 9.1 10.1
H U M A N FACTORS
334-Augu~t, 1975
Shoulder joint extension Range Mean S.D.
34-59 45.7 7.7
42-63 51.7 6.3
46-69 56.4 7.1
44-69 56.4 8.0
6.9
66-93 82.0 9.4
84-106 99.0 7.7
68-87 79.3 7.0
91-115 100.8 8.2
4E-62 51.4 5.4
27-47 33.8 6.5
27-46 36.2 5.7
24-58 39.7 10.8
28-50 38.8 8.3
59-75 64.7 5.9
Shoulder joint hor. flexion Range 119-140 Mean 129.9 S.D.
Shoulder joint hor. ext. Range Mean S.D.
Elbow flexion Range Mean S.D.
Knee flexion ange Mean S.D.
Hip flexion Range Mean S.D.
Hip extension Range Mean S.D.
Hip abduction Range Mean S.D.
140-152 125143 126-139 129-140 135-141 138.6 133.8 137.0 135.0 146.6 4.0 2.1 6.3 3.9 3.6 90-107 102-126 100.2 112.2 5.3 7.4
109-1 36 122.1 8.3
85-97 91.4 4.2
97-115 108.5
87-1 11 103.5 8.7
57-77 66.1 5.9
58-79 69.4 7.2
72-83 77.1 3.7
57-92 78.1 11.1
29-40 34.3 3.8
11-27 18.4 5.1
17-37 24.1 6.4
16-25 19.0 2.9
9-40 24.2 9.4
39-65 52.4 8.7
18-28 22.1 3.1
2339 29.8 5.8
25-35 30.4 2.8
26-51 40.6 8.5
5.9
Standard deviation
ive (p c .01). In no case was the Mark V superior to the Mark XII, either wet or dry. The results of each range-of-movement measurement are as follows: (1) Trunk flexion. No significant differences were found between the two suits; however, this movement is more difficult to perform in both suits in the water than on dry land. In the dry mode, the weight of the helmet 'helps to pull the trunk forward; in the water, the positive buoyancy of the Mark XI1 helmet somewhat hinders downward motion. (2) Trunk extension. The Mark XI1 allowed more flexibility in the water (p < .05). and for
the combined wet and dry data (p < .01). This movement is also difficult to perform in the water, being affected by the same factors as in trunk flexion, but to a lesser degree. (3) Trunk lateral flexion. The Mark XI1 was significantly more flexible in the dry mode only (p < .05).Buoyancy was aslight problem. (4) Trunk transverse rotation. There were no significant differences. Some restrictions of this movement were caused by suit materials, gas volumes, etc., but were equally limiting in both suits. (5) Shoulder joint abduction. In the water, the Mark XI1 allowed more movement for this
August, 1975-335
ARTHUR J. BACHRACH AND OTHERS
TABLE 4
Mean Percentage Loss of Diver FlexibilityCaused by the Mark V and Mark XI1 Diving Suits Movement
Trunk flexion Trunk extension Trunk lateral flexion Trunk transverse rotation
Shoulder joint abduction Shoulder joint flexion Shoulder joint extension Shoulderjointhor.flexion Shoulder joint hor. extension Elbow flexion Knee flexion Hip flexion Hip extension Hip abduction Overall mean loss Difference
Dry Mark V Mark VII 11.1 26.9 27.2 42.2 40.4 47.5 29.8 37.0
11.2 12.5 12.3 37.8 22.1 24.1 20.2 23.7
34.6 7.9 24.8 35.6 46.7 56.8
29.6 8.7 11.1 32.9 30.0 42.4 22.7
33.3 10.6
p
ns .05 .05
ns .01 .01
.05 .01
ns ns .01
ns ns .05
Wet Mark V Mark XI1 28.5 38.1 29.9 29.5 35.9 39.3 12.9 39.0
26.9 26.8 31.0 31.3 17.6 16.1 13.0 22.0
23.2 6.4 17.7 25.1 43.8 40.8 29.3
24.9 5.4 8.0 24.8 31.0 21.1 21.4
p
ns .05
ns ns .01 .01
ns .01
ns ns .01 ns
ns .01
7.9
p = level of significance ns = not significant
important motion of the arm (p < .Ol). In the data showed no significant differences beMark V, it was difficult to raise the arm much tween the two suits. beyond a horizontal plane, owing to interfer(1 0) Elbow flexion. No significant difference from the breastplate, which makes over- ences were found between the two suits. Suit head movements exceptionally difficult. if not materials and air within the sleeves caused impossible. slight restrictions (an average of 7% impair(6) Shoulderjoint flexion.This motion of the ment compared with swim suit flexibility). arm, similar to shoulderjoint abduction, is an This is the only movement that showed little important one for overhead work and was dif- or no restriction in either suit. ficult to perform in the Mark V. The Mark XI1 (1 1) Knee flexion. There was more flexibility was more flexible in all cases (p < .01). (p < .Ol) in the Mark XII, probably a result of (7) Shoulder joint extension. No statistically the difference in weight of the boots (a Mark V significant differences were found in the boot weighs 17.5 Ibs [7.9 kg], and a Mark XI1 water, but on land the Mark XI1 allowed more boot weighs 10 lbs [4.5 kg]). This opinion is freedom of movement. further supported by the fact that the range of (8) Shoulder joint horizontal flexion. motion in the Mark V increases in the water Movement was hampered by the bulky mate- where the boot weight has less effect than on rials of the two suits and by the gas volumes land. within thesuits.The breastplate in the MarkV (12) Hip flexion. There were no significant makes i t difficult to bring the arm straight differences between the two suits, either wet forward. For this particular motion, the Mark or dry, but both were better in the water than XI1 was significantly less restrictive (p < .01). on dry land, where interference from heavy (9) Shoulder joint horizontal extension. The boots was greater.
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336-August, 1975
(13)Hip extension.The MarkXII was better, but only when both wet and dry data were combined. This motion was difficult to measure accurately since even the baseline angle was small (around 30"). All the subjects had trouble performing it correctly in the water. (14) Hip abduction. The Mark XI1 was significantly superior, again probably a result of lesser boot weight. This ,movement (keeping the body vertical while lifting the leg and heavy boot out to the side) is particularly awkward and physically difficult in the dry mode. Five of the six subjects considered themselves too light in the Mark XI1 to adequately perform the trunk movements (trunk flexion, extension, and lateral flexion). Under actual working conditions weight would be adjusted, but to maintain consistency in this phase of testing, each suit was worn as designed, with the standard amounts Of weight.1t is possible that, with added weight, the Mark XI1 could
show greater trunk in the water. The one diver who had no complaints about his \,,eight had only 1% impairment of flexion in the water. The others found it difficult to keep their feet on the bottomwhile pulling against the buoyancy of the helmet. Individual differences in ment were apparent in all of the k g movemerits, particularly on land, where boot weight has a greater effect.
HUMAN F A C T O R S
The overall mean loss of mobility in the water was 21.4% for the Mark XII, and 29.3% for the Mark V, a difference of 7.9%. The results of this study indicate the Mark XI1 was clearly superior overall to the Mark V in both wet and dry modes. ACKNOWLEDGMENTS This research was funded by the Bureau of hledicine and Surgery, Navy Department, Research Su b t ask h14306.03.204DAC9. The opinions and statements contained herein are the private ones of the writers and are not tobeconstruedasofficialorreflecting theviewsoftheNavy Department or the naval service at large. The authors wish to thank F. W. Armstrong, the late K. J. Conda. and J. M.Woolley, Behavioral Sciences Department of the Naval Medical Research Institute, whoactedas subjects and provided technical assistance. We would also like to thank divers R. I. Ault and R. Radecki, of the U S . Navy Experimental Diving Unit, and W. E. Long. Jr., Environmental Biosciences Department of the Naval Medical Research Institute, for acting as subjects. The authors also wish to thank LT D. R. Chandler, MSC. USN, of the U S . Navy Experimental Diving Unit, for his encouragement and support.
REFERENCES Beatty. H.T. and Berghage. T. E. Diver anthropometrics. Washingt0n.D.C.: U.S.NavyExperimenta1DivingUnit Research Report 10-72. June, 1912. Dempster,W. T.Theanthropometryofbody action.Attrtafs o f t h e N e w YorkAcadeniyofSciertces, 1955.63.559-585. Egstr0m.G. H. Effect ofequipment on divingperformance. In Hro~zatzperfonnorice in scuba diving. Chicago: The Athletic Institute, 1970,516. Hertzberg. H. T. E. Engineering anthropology. In H. Van Cott and R. G. Kinkade (Ed.) Human engirweririggitide to eqtcipnzetifdesigti. Washington, D.C.: Superintendent of Documents. 1912. Kinney. J. S., Luria, S . M.,Ferris. S. H., andPau1son.H. hl. Optical andvisual testson the Navyprototypehardhat diving system. Groton. Connecticut: US. Naval Submarine Medical Research Laboratory. Report 73 1, 1972.
