TECHNICAL REPORT
`NATICK/TR-82/0ll
`
`Effects of Gender, Load, and
`Backpack on the Temporal and
`Kinematic Characteristics of Walking Gait
`Volume III
`
`BY PWLIP E. MARTIN
`AND
`RICHARD C. NELSON
`
`BIOMECHANICS LABORATORY
`THE PENNSYLVANIA STATE UNIVERSITY
`UNIVERSITY PARK, PENNSYLVANIA
`
`APRIL 1982
`
`TEeHNICAt LIBRARY
`U.S. ARMY NATICK R & Q LABORAIOltlfJ
`NATICK, MA 01760
`
`APPROVED FOR PUBLIC RELEASE; DlSTRIBUTION UNLIMITED
`
`Petitioner Ex. 1084 Page 1
`
`

`
`Petitioner Ex. 1084 Page 2
`
`

`
`UN tCLASSIFIED
`SECURITY CLASSIFICATION OF THIS PAGE ("04ej Date Ente___
`
`ýx
`
`C
`
`VOL
`
`'ub"TiFECTS OF GENDER, LOAD, AND BACKPACK
`ON THE TEMPORAL AND KINEMATIC CHARACTERISTICS OF
`WALKING GAIT
`
`7. AUTHOR(a)
`
`Philip E. Martin, M.S.
`Richard C. Nelson, Ph.D.
`9. PERFORMING ORGANIZATION NAME AND ADDRESS
`Biomechanics Laboratory
`The Pennsylvania State University
`University Park, Pennsylvania 16802
`II. CONTROLLING OFFICE NAME AND ADDRESS
`US Army Natick Research and Development Laboratories
`ATTN: DRDNA-ICCH
`Natick, Massachusetts
`01760
`14. MONITORING AGENCY NALE & ADDRESS(If ditferent ftim Controlling Office)
`
`REPORT DOCUMENTATION PAGE
`P FORM
`B.FORR
`i a0 i±ol
`A
`A.-~
`.
`GOVT ACCtSION NO. S. RECIPIENT'S CATALOG NUMUER
`I. REPORT NUMBER
`..
`NATICI(/TR-82/021
`
`____________
`S..
`Fil
`
`PT,, ORTP 'O
`COVERED
`Report for Perio
`
`October ] 1979 t August21,1981
`.
`6. PERFORMING ORG. REPORT NUMBER
`
`G. CONTRACT'OR GRANT NUMBER(a)
`
`DAAK60-79-C-0131
`
`10. PROGRAM ELEMENT, PROJECT, TASK
`AREA & WORK UNIT NUMBERS
`62,
`9p05
`6.2
`
`IS.
`
`12. REPORT DATE
`April 1982
`,UNSER oF PAGES
`78
`1S. SECURITY CLASS. (of thle report)
`
`UNCLASS IFIED
`ISO, DECL ASSI FICATION/OOWNGRAOING
`
`SC'4EDULE
`
`IS. DISTRIBUTION STATEMENT (of tsle Report)
`
`Approved for public release; distribution unlimited.
`
`17, DISTRIBUTION STATEMENT (of the abstract entered In Block 20, If different from Report)
`
`IS. SUPPLEMENTARY NOTES
`
`It. KEY WORDS (Continue an revers.e sde if necessry end identify by block number)
`loads
`load carrying
`walking
`males
`anthropometry
`military personnel
`females
`combative movement
`exercise
`frame-pack systems
`performance
`field tests
`
`4,
`
`20. AVIh AC? (Centilou,
`I Pepsi= ebb Nm
`fdlMtily' by block nule'ber)
`(cid:127)eeemand
`This study was conducted to determine the effects of loads worn or carried
`and the type ol" backpack used on parameters of the walking gait of men and women.
`Eleven men and eleven women participated in the test, with walking speed con-
`trolled at 4 mi/hr, unde'c each of the following load conditions: Load 1 - base-
`line (shorts, t-shirt, sneakers); Load 2 - fighting gear (utility shirt and
`trousers, boots,, ALICE fighting gear); Load 3 - combat gear (Load 2 plus PASGT
`helmet, PASGT armor vest, simulated M16 rifle); Load 4-combat gear and 20-lb
`
`W1473
`
`1 0pv 3ss
`I
`
`Op
`
`is OsmCIETh
`
`UNCLASSIFII-
`
`SECURITY CLASSIIiCATION OF THIS 10049
`
`(01b Date Bnterea)
`
`Petitioner Ex. 1084 Page 3
`
`

`
`SEcusITY CLAShIVICATON OF THIS PAOC(lWhM DGa Rn(cid:127)Rt
`
`- combat gear and
`backpack load (Load 3 plus backpack with 20-lb load); Load 5
`The men were
`35-lb backpack load (Load 4 plus an additional 15 lb in pack).
`also tested under a sixth load condition: Load 6 - combat gear and 50-lb back-
`The subjects carried loads
`pack load (Load 4 plus an additional 30 lb iin pack).
`Two of these consisted of
`4 through 6 using four different backpack systems.
`Army frames equipped with the standard Army pack. The third was an experimental
`The fourth
`item, a packboard made of rigid aluminum, used with the Army pack.
`internal frame system. The dependent
`backpack was a commercially-available,
`measures analyzed were stride length, rate, and velocity, single leg contact
`time, double support time, swing time, and trunk angle. Analyses of the data
`the trunk angles maintained by the
`difference in
`little
`indicated that there was
`the men generally had greater stride lengths and
`However,
`men and the women
`shorter stride raes than the women. There was a tendency for subjects to
`decrease stride length and increase stride rate as the load was increased. Also,
`Few
`there was an increase in forward lean of the body.
`between Loads 4 and 6,
`the characteristics of walking gait could be attributed to
`differences in
`differences in backpack designs.
`
`SECOMITY CLASSIFICATION OF THIS PAGEt(Whn Dose Xntor*4
`
`Petitioner Ex. 1084 Page 4
`
`

`
`PREFACE
`
`This is
`the third of four volumes comprising the final report of research
`performed under Contract Number DAAK60-79-C-0131 with the Individual Protection
`Laboratory, US Army Natick Research and Development Laboratories, Natick,
`Massachusetts.
`The work was formulated and directed by Drs. Carolyn K. Bensel
`and Richard F. Johnson, Human Factors Group, Iidividual Protection Laboratory.
`Dr. Bensal was the contract monitor ar,', Dr. Johnson was the alternate.
`
`The authors would like to express their appreciation to several individuals
`for their assistance and cooperation during this project. Mr.
`In-Sik Shin,
`Mr. Wlodzimierz Erdmann, Mr. Li Cheng Zhi, and Ms. Maureen Breckenridge provided
`valuable assistance during the data collection and data processing portions
`of the project. Mr. John Palmgren provided technical assistance particularly
`for the filming procedures used for data collection. Finally, the efforts and
`cooperation of Major Richard Bartolomea, Marine Instructor Officer for the
`R.O.T.C. program at The Pennsylvania State University and his staff were
`responsible for providing the research facility used for the data collection.
`The quality of the assistance of these individuals was greatly appreciated.
`
`INS,'ECTED
`
`Ancession For
`
`NTIS GRA&I
`DTIC TAB
`
`Justifilcation-_
`
`_Distribut i on/
`
`AvailnbilitY Codes•
`Avail and/or
`specia~l
`
`Dist
`
`I,,
`
`1- - .
`
`Petitioner Ex. 1084 Page 5
`
`

`
`TABLE OF CONTENTS
`
`PREFACE
`
`LIST OF FIGURES
`
`LIST OF TABLES
`
`INTRODUCTION
`
`PROCEDURES
`
`Test Sessions
`Subjects
`Backpack Systems
`ALICE LC-2
`ALICE LC-1
`LOCO
`PACKBOARD
`Load Conditions
`Load 1
`Load 2
`Load 3
`Load 4
`Load 5
`Load 6
`Data Coilection Procedures
`Stride length
`Stride rate
`Stride velocity
`Single leg contact time
`Double support time
`Swing time
`Trunk angle
`Statistical Procedures
`
`RESULTS AND DISCUSSION
`
`Stride Velocity
`Effect of Gender and Load
`Effect of Gender, Backpack, and Load
`Effects of Backpackpack and Load
`Comparative Analysi's of the Influence of Load
`
`SUMMARY AND RECOMMENDATIONS
`
`3
`
`Page
`
`1
`
`5
`
`6
`
`11
`
`12
`
`12
`12
`13
`13
`13
`13
`13
`14
`14
`14
`14
`15
`15
`15
`15
`16
`16
`17
`17
`17
`17
`17
`17
`
`18
`
`18
`19
`24
`30
`34
`
`37
`
`i
`
`Petitioner Ex. 1084 Page 6
`
`

`
`TABLE OF CONTENTS (continued)
`
`REFERENCES
`
`APPENDICES
`
`A. Clothing and Equipment Used in This Study
`
`B. ANOVA Summary Tables - Stride Velocity Analyses
`
`C. ANOVA Summary Tables - Analyses of Gender
`and Load (1-3)
`
`D. ANOVA Summary Tables - Analyses of Gender,
`Backpack, and Load (4-5)
`
`E.
`
`ANOVA Summary Tables - Analyses of Backpack
`and Load (4-6)
`
`Page
`
`39
`
`41
`
`'57
`
`60
`
`65
`
`75
`
`I.
`
`"*
`
`44
`
`A
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.*~=
`
`Petitioner Ex. 1084 Page 7
`
`

`
`LIST OF FIGURES
`
`Figure 1.
`
`Figure
`
`2.
`
`Figure
`
`3.
`
`Mean double support time versus Load
`Condition for the men and women subjects.
`
`Means for stride length versus Load
`Condition for the men and women subjects.
`
`Meanp for swing time versus Load
`Condition for the men and women subjects.
`
`,!
`
`(cid:127)
`
`Figure
`
`4.
`
`Trunk angle values versus Load Condition for
`the men and women subjects.
`
`Figure A-I.
`
`ALICE Fighting Gear.
`
`Figure A-2.
`
`ALICE Pack.
`
`Figure A-3.
`
`ALICE LC-2 Frame.
`
`Figure A-4.
`
`ALICE LC-1 Frame.
`
`Figure A-5.
`
`PACKBOARD
`
`Figure A-6.
`
`LOCO.
`
`Page
`
`22
`
`25
`
`29
`
`36
`
`43
`
`45
`
`47
`
`50
`
`52
`
`54
`
`5
`
`1,
`
`Petitioner Ex. 1084 Page 8
`
`

`
`LIST OF TABLES
`
`Table 1. Physical Characteristics of Subjects
`
`Table 2. Approximate Values for Selected Characteri3tics
`of the Four Backpacks
`
`Table 3. Mean Load Values (kg) for Men and Women for All
`Load Conditions
`
`Table 4. Mean Values of Stride Velocity for Gender and Load
`
`Table
`
`5. Mean Values of Stride Velocity for Gender,
`Backpack, and Load
`
`Table
`
`6. Mean Values of Stride Velocity for Backpack and
`Load
`
`Table
`
`7. Mean Values of Stride Length (m) for Gender and
`Load
`
`Table
`
`8. Mean Values of Stride Rate (strides/sec) for
`Gender and Load
`
`Table
`
`9. Mean Values of Single Leg Contact Time (msec)
`for Gender and Load
`
`Table 10. Mean Values of Double Support Time (msec) for
`"Gender and Load
`
`Table 11. Mean Values of Swing Time (msec) for Gender and
`Load
`
`Table 12. Mean Values of Trunk Angle (degrees) for Gender
`and Load
`
`Table 13. Mean Values of Stride Length for Gender, Backpack,
`and Load
`
`Table 14. Mean Values of Stride Rate for Gender, Backpack,
`and Load
`
`"Table 15. Mean Values of Single Leg Contact Time for
`Gender, Backpack, and Load
`
`Table 16. Mean Values of Double Support Time for Gender,
`Backpack, and Load
`
`Table 17. Mean Values of Swing Time for Gender, Backpack,
`and Load
`
`Page
`
`13
`
`14
`
`15
`
`18
`
`18
`
`19
`
`20
`
`20
`
`21
`
`21
`
`23
`
`23
`
`24
`
`26
`
`27
`
`28
`
`28
`
`6
`
`121,
`
`Petitioner Ex. 1084 Page 9
`
`

`
`LIST OF TABLES (continu.d)
`
`Table 18.
`
`Mean Values of Trunk Angle for Gender,
`Backpack, and Load
`
`Table 19.
`
`Table 20.
`
`Table 21.
`
`Table 22.
`
`Table 23.
`
`Mean Values of Stride Length (m) for Backpack
`and Load
`
`Mean Values of Stride Rate (strides/saec) for
`Backpack and Load
`
`Mean Values of Single Leg Contact Time (msec)
`for Backpack and Load
`
`Mean Values of Double Support Time (msec)
`for Backpack and Load
`
`Mean Values of Swing Time (msec) for Backpack
`and Load
`
`Table 24.
`
`Mean Values of Trunk Angle (degrees) for Backpack
`and Load
`
`Table 25.
`
`Mean Values of Stride Length, Stride Rate, and
`Trunk Angle for All Loads
`
`Table B-1.
`
`ANOVA Summary of Stride Velocity for Gender and
`Load (1-3)
`
`Table 3-2.
`
`ANOVA Summary of Stride Velocity for Gender,
`Backpack, and Load (4-5)
`
`Table B-3.
`
`ANOVA Summary of Stride Velocity for Backpack and
`Load (4-6)
`
`Table C-1.
`
`ANOVA Summary of Stride Length for Gender and
`Load (1-3)
`
`Table C-2.
`
`ANOVA Summary of Stride Rate for Gender and
`Load (1-3)
`
`Table C-3.
`
`ANOVA Summary of Single Leg Contact Time for
`Gender and Load (1-3)
`
`Table C-4.
`
`ANOVA Summary of Double Support Time for Gender
`and Load (1-3)
`
`Table C-5.
`
`ANOVA Summary of Swing Time for Gender and
`Load (1-3)
`
`Page
`
`18
`
`31
`
`32
`
`32
`
`33
`
`33
`
`34
`
`35
`
`58
`
`58
`
`59
`
`61
`
`61
`
`62
`
`62
`
`63
`
`!
`
`7
`
`-
`
`*,',e
`
`Petitioner Ex. 1084 Page 10
`
`

`
`LIST OF TABLES (continued)
`
`Table C-6.
`
`ANOVA Summary of Trunk Angle for Gender and
`Load (1-3)
`
`Table D-1.
`
`ANOVA Summary of Stride Length for Gender,
`Backpack and Load (4-5)
`
`Table D-2.
`
`ANOVA Summary of Stride Rate for Gender,
`Backpack, and Load (4-5)
`
`Table D-3.
`
`ANOVA Summary of Single Leg Contact Time for
`Gender, Backpack, and Load (4-5)
`
`Table D-4.
`
`ANOVA Summary of Double Support Time for
`Gender, Backpack, and Load (4-5)
`
`Table D-5.
`
`ANOVA Summary of Swing Time for Gender, Backpack,
`and Load (4-5)
`
`Table D-6.
`
`ANOVA Summary of Trunk Angle for Gender, Backpack,
`and Load (4-5)
`
`Table D-7.
`
`Cell Mean Values of Stride Length
`Backpack, and Load
`
`(m) for Gender,
`
`Table D-8.
`
`Cell Mean Values of Stride Rate (stride/sec)
`for Gender, Backpack, and Load
`
`Table D-9.
`
`Cell Mean Values of Single Leg Contact Time
`(msec) for Gender, Backpack, and Load
`
`Table D-10. Cell Mean Values of Double Support Time (msec)
`for Gender, Backpack, and Load
`
`Table D-11. Cell Mean Values of Swing Time (msec) for
`Gender, Backpack, and Load
`
`Table D-12. Cell Mean Values of Trunk Angle (degrees) for
`Gender, Backpack, and Load
`
`Table E-1.
`
`ANOVA Summary of Stride Length for Backpack and
`Load (4-6)
`
`Table E-2.
`
`ANOVA Summary of Stride Rate for Backpack and
`Load (4-6)
`
`Table E-3.
`
`ANOVA Summary of Single Leg Contact Time for
`Backpack and Load (4-6)
`
`Page
`
`63
`
`66
`
`67
`
`68
`
`69
`
`70
`
`71
`
`72
`
`72
`
`72
`
`73
`
`73
`
`73
`
`76
`
`76
`
`77
`
`Petitioner Ex. 1084 Page 11
`
`

`
`LIST OF TABLES (continued)
`
`Table E-4.
`
`ANOVA Summary of Double Support Tinie for
`Backpack and Load (4-6)
`
`Table E-5.
`
`ANOVA Summary of Swing Time for Backpack and
`Load (4-6)
`
`Table E-6.
`
`ANOVA Summary of Trunk Angle for Backpack and
`Load
`
`Page
`
`77
`
`78
`
`78
`
`9
`
`9/1
`
`1I
`II
`
`I
`
`4
`
`t;i
`
`Ii
`
`S(cid:127),(cid:127) (cid:127) -- (cid:127)(cid:127)
`
`,:(cid:127)
`
`(cid:127)
`
`/
`
`l
`
`(cid:127)'(cid:127)'(cid:127)(cid:127)
`
`>(cid:127)
`
`......
`
`,(cid:127)
`
`......
`
`.. 1
`
`Petitioner Ex. 1084 Page 12
`
`

`
`Effects of Gender, Load, and Backpack on the Temporal
`and Kinematic Characteristics of Walking Gait
`
`INTRODUCTION
`
`This is the third of four studies on the biomechanics of load carrying
`behavior being carried out in the Riomechanics Laboratory at The Pennsylvania
`State University under the direction and sponsorship of the Army Natick
`Laboratories.
`The first two studies in this series were examinations of
`easy standing, vertical jumpirg, and combative movement performance of men
`and women under various backpack and load conditions. 1 , 2 Because a foot
`soldier may spend a considerable amount of time walking,
`it
`is
`important
`to have some knowledge of the influence of the gender of the soldier, of
`different load carrying systems, and of the magnitude of load on walking gait.
`Consequently,
`it was the purpose of this experiment to examine the effects
`of gender,
`load and backpack type on the temporal and kinematic characteristics
`of the walking gait.
`
`Previous research on the biomechanics of load carrying behavior performed
`by Nelson, Clark, and Hinrichs 3 examined the influence of gender, body size,
`and backpack on four aspects of the vertical ground reaction force during two
`speeds of walking - 4.8 and 8.0 km/hr. These speeds are slightly slower and
`slightly faster than a typical walking speed for most individuals. The four
`aspects of the ground reaction force examined were:
`1) contact time, 2) maximum
`force during initial contact time, 3) minimum force during mid-support, and
`4) maximum force during push-off.
`The analyses yielded similar trends in
`ground reaction forces for both speeds of walking.
`The results also demonstrated
`differences among males and females and persons of different body sizes.
`Differences between backpacks were not detected, however, using this ground
`reaction data.
`In particular,
`the results showed that contact time for female
`and small subjects was less than that for male and large subjectý..
`Few
`differences were found for the three force parameters (Ref.
`3).
`
`1
`
`S~February
`
`Nelson, R.C. and P.E. Martin. Volume I. Effects of Gender and Load on
`Combative Movement Performance (Tech. Rep. NATICK/TR-82/01i). Natick,
`Massachusetts: US Army Natick Research and Development Laboratories,
`1982.
`Nelson, R.C. and P.E. Martin. Volume II. Effects of Gender, Load, and
`
`Backpack on Easy Standing and Vertical Jump Performance (Tech. Rep.
`NATICK/TR-82/016). Natick, Massachusetts: US Army Natick Research and
`Development Laboratories, March 1982.
`
`Nelson, R.C., T.E. Clarke, and R.N. Hinrichs. An Investigation into the
`Biomechanics of Load Carrying: The Effects of Gender, Body Size, and
`Backpack on Load Carrying Behavior. Nat~ck, Massachusetts: US Army Natick
`Research and Development Laboratories,
`in preparation.
`
`*2
`
`Petitioner Ex. 1084 Page 13
`
`

`
`Test Sessions
`
`PROC EDURES
`
`Each subject participated in two test sessions. Because it was
`important for subjects to be thoroughly familiarized with the data collection
`procedures so as to avoid any disturbance of their normal walking pattern,
`the first test session was used as a practice session. During this session,
`the test protocol was explained to each subject. Following this explanation,
`the subjects performed a number of practice trials under a few selected load
`conditions. The number of trials and load conditions used during this session
`varied from subject to subject depending upon how rapidly they adapted to
`the experimental conditions. At a minimum, each subject performed ten trials
`under two load conditions. These two load conditions were Loads 1 and 4
`which are described later in this volume. In addition to familarizing the
`subjects with the testing procedures, the practice session also helped to
`reduce the time needed to do the actual data collection during the second
`session.
`
`I
`
`The data collection session comnsisted of the filming of the walking
`gait of each subject under several different load and pack configurations.
`Only one walking speed was used for this study. In earlier work in which
`walking was analyzed, two walking speeds, 4.8 and 8.0 kin/hr were employed.
`The walking speed used in this project was intermediate to those of the first
`project. The 6.4 km/hr rate represented a near normal walking speed for most
`subjects. In order to control the walking speed, it was necessary to have
`some indication of the speed for each trial. To accomplish this, a system
`was established to time each subject over a five-meter zone in the filming
`area. Any trial in which the walking speed was within five percent of the
`6.4 km/hr target speed was accepted as a good trial. Those outside of
`+-5% range were repeated.
`
`Sujects4
`
`Eleven men and eleven women, all students in the Army R.O.T.C. Program
`at The Pennsylvania State University, served as subjects for the study. This
`group of twenty-two was a subset of the original thirty subjects who
`participated in the first study in this series (Ref. 1). These individuals
`were highly motivated as subjects for this project because of their personal
`interest and experience in load carrying. As was noted in the report on the
`first study, these subjects, based on their physical characteristics, were
`considered to be representative of U.S. Army personnel (Ref. 1). Table 1
`contains mean values for the age, height, and weight of the male and female
`subjects who participated in this study.
`
`12
`
`.
`
`Petitioner Ex. 1084 Page 14
`
`

`
`Table 1
`
`Physical Characteristics of Subjects
`
`Gender
`
`N
`
`Age
`
`(yrs)
`
`X
`
`S.D.
`
`Height
`X
`
`(cm)
`
`S.D.
`
`Weight
`X
`
`(kg)
`
`S.D.
`
`Men
`
`Women
`
`11
`
`1.1
`
`20.9
`
`1.8
`
`176.9
`
`5.7
`
`71.0
`
`7.2
`
`20.8
`
`1.7
`
`166.4
`
`4.8
`
`W08
`
`10.9
`
`Backpack Systems
`
`The four backpacks used in this study included three with external. framesI
`and one with an internal frame. The same top-leading pack, a standard Army
`item, was used on each of the external frames. A brief description of each
`system is included here. Appendix A contains additional information on these
`
`items.
`
`a. ALICE LC-2 is the Army's standard frame. It is made of aluminum
`tubing and has foam-padded shoulder and lower back straps. The waist belt,
`made of wide nylong webbing, is attached to the padded back strap.
`
`b. ALICE LC-1 was the standard Army frame prior to the introduction of
`the LC-2. The frame itself is one of the same design as the LC-2. However,
`the shoulder and back straps are of different dimensions and are not foam-
`padded. In addition, the waist strap is made of narrow webbing and attaches
`to the frame.
`
`c. LOCO is a commercially-available, internal-frame system. The frame
`consists of two, vertical, aluminum stays which extend the length of the
`pack and are on the side of the pack closest to the wearer's body. The pack
`itself is a top-loading bag to which foam-padded shoulder straps and a waist
`belt are attached.
`
`d. PACKBOARD is an experimental item which was fabricated for this study.
`It consists of a flat sheet of aluminum. The shoulder, back, and waist straps
`attached to it are identical to those used with the. ALICE LC-2.
`
`The physical dimensions and weights of the p.acks are listed in Table 2.
`
`*
`
`*
`
`13
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`Petitioner Ex. 1084 Page 15
`
`

`
`Table 2
`
`Approximate Values for Selected
`Characteristics of the Four Backpacks
`
`Backpack
`
`Length*
`
`Width*
`
`Delpth*
`
`Frame and
`Bag Weight**
`
`ALICE LC-2
`ALICE LC-.1
`
`LOCO
`PACKBOARD
`
`52 cm,
`51
`
`46 cm
`46
`
`61
`54
`
`35
`46
`
`40 cm
`39
`
`30
`32
`
`3.23 kg
`2.84
`
`1.41
`3.57
`
`*Dimensions were measured with the pack loaded with the
`basic 9.1 kg load (Load 4) which consisted of a sleeping
`bag, mattress, waterproof clothes bag, poncho, socks, and
`undershirt. The length and width dimensions were the
`greatest values for the frame-pack system in their
`respective directions. The depth dimension was an estims±te
`of the maximum distance the pack projected from the body.
`
`**Combined weight when empty.
`
`Load Conditions
`
`In addition to using four different backpacks, the subjects performed
`* their normal walking gait under several different load conditions. These
`* loads were the same as those used in the other two studies in this series
`(Refs. 1 and 2). In all, there were six different load conditions carefully
`selected so as to cover a wide range of typical military loads. The male
`subjects performed under all six load conditions, while the female subjects
`performed only under the first five load conditions. ia following summary
`describes the six load conditions used in the testing. Additional information
`on the clothing and equipment used is pres Lted in Appendix A.
`
`Load I served as the baseline condition. Subjects wore t-shirt, shorts,
`socks, and sneakers.
`
`Load 2 was considered the fighting gear condition. The subjects wore
`socks, underwear, utility shirt and trousers, boots, and the standard
`fighting gear which included a water-filled canteen with cover, intrenching'T
`tool with carrier, and two small arms ammo cases containing 1.75 kg sandbags.
`
`Load 3 was designated the combat gear condition. The subjects wore a
`PASGT helmet and armor vest and carried a simulated M-16 rifle in addition to
`those items included in Load 2.
`
`14
`
`i
`
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`Petitioner Ex. 1084 Page 16
`
`

`
`FIRT
`
`Load 4 included all items from Load 3 plus one of the four backpacks
`containing a 20 pound (9.1 kg)
`load.
`This load consisted of a sleeping bag,
`mattress, waterproof 'lothes bag, poncho, socks, and undershirt.
`
`Load 5 included all
`items from Load 4 plus an additional weight of
`15 pounds (6.8 kg) placed in the pack. The extra load consisted of three,
`5 pound (2.3 kg) barbell disks.
`
`Lead 6 was carried by the men only and included sll items from Load 4
`plus 30 additional pounds (13.6 kg)
`in
`the form of three, 10 pound (4.5 kg)
`disks placed in
`the pack.
`
`Note that the magni'
`ides of Loads 4, 5, and 6 differed slightly with
`the backpack used since the weights of the packs differed somewhat. Table 3
`summarizes the magnitudes of all
`loads,
`including Loads 4,
`5, and 6 in
`combination with each pack.
`
`Table 3
`
`Mean Load Values (kg) for Men and
`Women for All Load Conditions
`
`Backpack
`Men (N-11)
`
`1
`.76
`
`2
`9.46
`
`Load Condition
`3
`4
`17.67
`
`5
`
`6
`
`ALICE LC-2
`
`ALICE LC-l
`
`LOCO
`
`PACKBOARD
`Load Mean
`
`Women (N-11)
`ALICE LC-2
`ALICE LC-1
`
`LOCO
`
`PACKBOARD
`
`Load Mean
`
`.56
`
`9.04
`
`16.92
`
`43.62
`
`43.21
`
`41.76
`
`43.94
`43.13
`
`30.01
`
`29.60
`
`28.15
`
`30.33
`29.52
`
`29.26
`28.85
`
`27.40
`
`29.58
`
`28.77
`
`36.81
`
`36.40
`
`34.95
`
`37.13
`36.32
`
`36.06
`35.65
`
`34.20
`
`36.38
`
`35.57
`
`Data Collection Procedures
`
`Standard high speed cinematography techniques were used to film each
`subject. Because the movements of the walking gait occur primarily in
`the
`sagittal plane of the body, only one camera was used and a planar analysis
`completed. A Locam camera manufactured by Redlake Corporation and capable
`of running at speeds as high as 500 frames per second was preset to run at
`50 frames per second for this experiment. A timing unit placed in the field
`
`|1
`
`15
`
`Petitioner Ex. 1084 Page 17
`
`

`
`of view was used to determine the actual camera speed. In addition, two
`reference numbers were used to identify the suibject and the condition und~er
`which he was performing. Markers were placed on critical body locations so
`as to facilitate the filmi analysis. These markers were used to estimate
`the joint centers of the ankle, knee, hip, an(J shoulder.
`
`For each male subject, there was a total of 15 conditions. These
`consisted of the three lowest loads in which no packs were used plus the
`three highest loads in combination with each of the four backpacks.
`Consequently, there were 12 conditions that involved the four packs and
`three without packs. For the female subjects, there were 11 conditions.
`Since the females were not tested under the highest load, there was one
`fewer condition for each of the four packs, or four fewer conditions for
`the females than for the males.
`
`The order of presentation of the backpack and load conditions was
`similarly determined for both the male and female subjects. All subjects
`were first tested under Loadb 1, 2, and 3 in sequential order. These were
`then followed by the test conditions involving the four packs. For each
`subject, the order of presentation of the four packs was randomly determined.
`Loads 4, 5, and 6 for the men and Loads 4 and 5 for the women were then
`randomly ordered for each pack. Consequently, each subject performed all
`loads for a single pack before changing packs. For each backpack and load
`condition under which a subject performed, one acceptable trial was required.
`The decision to collect only one trial for each condition was based on the
`large time demands associated with the film analysis procedures used to
`obtain the walking data and bacause each subject was well practiced prior to
`the data collection. A short rest interval was provided between trials so
`that the influence of fatigue could be minimized. This interval was
`approximately two minutes in length which generally was the time needed by
`the experimente..s to make necessary adjustments for changes in pack and
`load conditions.
`
`The films were analyzed using a Vanguard projection system with a Bendix
`digitizer. This system provided on-line data recording capabilities on the
`laboratory computer. Values for seven variables which were used to describe
`the temuporal and kinematic characteristics of the gait of each subject were
`obtained from the film. During the filming, the field of view was established
`to include three to four strides. The experimenters were then able to select
`the two strides which were closest to the center of the field of view. In
`all trials, the film analysis was initiated at a position when the subject's
`* right heel made contact with the ground and continued until the next right
`heel strike occurred. This provided two complete strides for analysis and
`meant that two measures for each variable were obtained. These values were
`then averaged and the average values for each variable were used in the
`statistical analysis. The following summarizes the measurement of each of
`the seven variables:
`
`1. Stride length in meters was measured as the distance from the point
`of one heel strike to the point of the next heel strike.
`
`2. Stride rate was calculated by measuring the stride time which was
`the time between two heel strikes, and then taking the reciprocal
`of the stride time. Stride rate was then represented as the number
`of strides completed per second.
`
`16
`
`.
`
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`
`Petitioner Ex. 1084 Page 18
`
`

`
`3. Stride velocity was calculated by taking the product of stride length
`and stride rate which resulted in stride velocity in meters per second.
`
`4. Single leg contact time was measured as the time from heel strike
`of one leg until the foot of the same leg left the ground to begin
`the swing phase.
`
`5. Double support time was the time during which both feet were in
`contact with the ground. This was the time from heel contact of
`one leg until the foot of the other leg left the ground.
`
`6.
`
`Swing time was the time of non-support for one leg and was measured
`from a point when the foot of one leg left the ground until heel
`strike of the same leg.
`
`7. Trunk angle was a measure of the forward inclination of the trunk
`at a point when the foot of one leg left the ground. The angle
`measured was that between the horizontal and a line connecting the
`shoulder joint and the hip joint such that a greater forward
`inclination resulted in a smaller angular measure.
`
`Statistical Procedures
`
`The program ANOVR, originally created by Gordon F. Pitz of Southern
`Illinois University and modified by Dr. Paul A. Games 4 of the Educational
`Psychology Department at The Pennsylvania State University, was used to
`analyze three different statistical designs used in this pahse of the project.
`In addition,
`the Tukey Wholly Significant Difference (WSD)
`test was used
`as a follow-up test to determine how sample means differed from one another
`when significant F values were obtained in
`the ANOVR results. The following
`represent the two, 2-factor designs and one, 3-factor design used: Gender
`vs. Load (for Loads 1-3), Backpack %,s. Load (Loads 4-6 for the men only),
`and Gender vs. Backpack vs. Load (Loads 4-5). A conventional analysis of
`variance logic was used to assess the results of the ANOVR runs. For the
`2-factor designs, tae interaction was first examined. The lack of a significant
`interaction indicated that the effect of one factor was the same from level
`to level of the second factor. Consequently,
`the main effects sufficiently
`described the results of the analysis.
`If
`the interaction was significant,
`however, an examination of the main effects no longer gave an adequate
`representation of the trends presented in the data. Follow-up analyses,
`therefore,
`included an examinc.tion of the simple effects. Because of an
`a priori interest in the main effects,
`they were examined and reported even
`when a significant interaction existed. The assessment of the 3-factor design
`was an extension of this same logic.4
`
`Games, P.A., G.S. Gray, W.L. Herron, A. Pentz, and G.F. Pitz. Analysis
`of Variance with Repeated Measures. University Park, PA: The Pennsylvania
`State University Computation Center, June 1979.
`
`17
`
`Petitioner Ex. 1084 Page 19
`
`

`
`Stride Velocity
`
`RESULTS AND DISCUSSION
`
`The walking velocity of each subject was limited to a + 5% range around
`If the velocity was adequately controlled, then
`6.4 km/hr, or 1.782 m/sec.
`the results of the analysis of variance (ANOVA) of st--ide velocity should
`be non-significant.
`In facL, thQ results did show that there were no
`significant differences at the .05 level in walking speed between any of
`the experimental conditions. The grand mean for the 374 observations which
`represented all conditions was 1.834 m/sec. This value is slightly higher
`than the 1.782 m/sec target speed but is well within the + 5% range
`(1.699 m/sec to 1.878 m/sec).
`The mean values for stride velocity generated
`by each of the three ANOVA runs are shown in Tables 4,
`5, and 6. The vertical
`lines which connect the mean values are used to show non-significance.
`The
`ANOVA summary tables are included in Appendix 3.
`
`Table 4
`
`Mean Values of Stride Velocity for Gender and Load
`
`Main Effect
`Gender
`Men
`Women
`
`Load
`
`1
`2
`3
`
`Stride Velocity (m/sec)
`
`1.8261
`1.843
`
`1.824
`1.839
`1.840
`
`Mean Values of Stride Velocity for Gender, Backpack, and Load
`
`Table 5
`
`Main Effect
`Gender
`Men
`Women
`Backpack
`ALICE LC-2
`ALICE LC-l
`LOCO
`PACKBOARD
`
`Load
`
`4
`5
`
`Stride Velocity (m/sec)
`
`1.829
`1.845
`
`1.843
`1.828
`1.841
`1.836
`
`1.843
`1.832
`
`18
`
`Petitioner Ex. 1084 Page 20
`
`

`
`Table 6
`
`Mean Values of Stride Velocity for Backpack and Load
`
`Main Effect
`
`Stride Velocity (m/sec)
`
`Backpack
`
`ALICE LC-2
`ALICE LC-l
`LOCO
`PACKBOARD
`
`Load
`
`4
`
`5
`
`6
`
`1.838I
`1.826
`1.829
`1.822
`
`1.833
`
`1.826
`
`1.629
`
`Effect of Gender and Load
`
`A2-factor AN'OVA was used to evaluate the differences between men aad4
`women and among Loads 1, 2, and 3 for the seven variables selected to describe
`the gait of each subJect. The mean values and the statistical results for
`six of the seven variables (excluding stride velocity) are discussed and
`presented in tabular form below. The six variables include stride length,
`stride rate, single leg contact time, double support time, sw.ing time, and
`trunk angle. The ANOVA sutmmary tables ate shown in Appendix C. In all of
`the following tables presenting statistical results, mean values which are
`not connected by a horizontal or vertical line are significantly different
`at the .05 level, and those which are connected are not statistically differenL,
`In addition, only the main means were analyzed in follow-up procedures when
`there was no significant interaction since an examination of simple effects
`was not required. The cell means are included for completeness, however,
`regardless of the significance of the interaction.
`
`Table 7 contains the mean values for stride length. The ANOVA results
`indicated no significant interaction (F =2.40) existed between gender and
`load. An examination of the main means then showed no significant difference
`between the men and women (F = 3.28), although the men did tend to have longer
`stride lengths, but a signi~ticant load effect (F -7.69) was obtained.
`Further analysis showed that the subjects had a significantly longer stride
`length under the intermediate load condition, Load 2, than under Loads 1 and 3,
`which were not statistic