Anthropometric Characteristics of Feet of Soldiers in the New Zealand Army

MILITARY MEDICINE, 176, 4:438, 2011 Anthropometric Characteristics of Feet of Soldiers in the New Zealand Army Marian L. Baxter, BPhsEd (Hons) * ; David G. Baxter, DPhil ABSTRACT Lower limb and lower back injuries are prevalent within the New Zealand (NZ) Army: independently collected data shows these to be most prevalent, with on average 10% of military personnel affected by such an injury at any time. To improve the quality and appropriateness of footwear, it is essential that normative foot anthropometric data is collected from NZ Army personnel. NZ Army personnel ( n = 807) were included in this study; data on foot length, circumference, width, and arch heights were collected. It was found that the NZ Army personnel had notable differences in feet anthropometry compared to an exemplary model for the NZ general population, specifically in terms of arch height. It was also found that a substantial proportion (approximately 50%) of personnel tested could not be provided with a boot that fit (mainly Maori and Pacific Island soldiers) because of a limited width range of the currently issued boot. INTRODUCTION The aim of this study was to develop a preliminary data set of the anthropometric characteristics of feet of soldiers within the New Zealand (NZ) Army. The purpose of this study is to allow better informed manufacture of footwear and, therefore, to reduce the incidence of related overuse injury. To do this, 807 military personnel were included in the study. Data were collected based on boot size, foot width, length, circumference, and arch height. Data were grouped and analyzed using available comparisons. Lower limb and lower back injuries are prevalent within the NZ Army. Data collected from the Accident Compensation Corporation (ACC) indicates that over a period of 5 years, 10% of the regular force was consistently affected by such injuries, which make these the most prevalent within the military population. Specific injuries of particular relevance here include stress fractures of the shin, stress fractures of the foot, knee injury or pain, hip injury or pain, and lower back injury or pain 1,2 (NZ Army ACC data). This is an important issue, as such injuries prevent the soldiers from attending the daily training; this is even more important during basic training as it has been reported that between a third 3 and a fifth 4 of recruits sustain such an injury during the first month of basic training, many of which require so many days off that the recruit then has to repeat the whole basic training course. 3,4 The biomechanical model of human movement suggests that kinetics and kinematics of movement follow a chain. The lower back and lower limb comprise a kinetic chain that starts with the foot. 5 7 It is, therefore, important to gather normative anthropometric data on feet within the NZ Army to better inform decisions on injury prevention, as it may be possible that those who are at risk are anthropometrically different to those at low risk. *School of Preventive and Social Medicine, University of Otago, PO Box 913, Dunedin 9054, New Zealand. School of Physiotherapy, 325 Great King Street, University of Otago, Dunedin 9054, Otago, New Zealand. This has been an area of developing research interest, with investigations focusing on foot structure and its relation to musculoskeletal overuse injury, 8 and in the past few years, targeted samples of the Australian military have been assigned specific interventions based on their foot anatomical characteristics.9 It has long been recognized in literature that fit of footwear has potential relevance in preventing injuries 10 ; therefore, knowledge of foot shape is imperative in producing well-fitting boots and consequently reducing injury. Despite this, there is currently no literature available on the anthropometric characteristics of the NZ population or the Army. Furthermore, no similar study has been published in other military populations. In the case of New Zealand, the population has such a unique ethnic diversity accompanied by anthropometric differences. wear designed overseas (as is currently the case) without reference to the characteristics of the NZ foot is always likely to be problematic. This study aimed to collect normative data of anthropometric foot characteristics from a representative sample of soldiers from the NZ Army and to describe differences with data for the general population. The ultimate goal of this work was to provide valid, accurate, and reliable data to allow comparison between at risk versus low risk groups and to inform production of appropriate and well-fitting footwear. SUBJECTS A randomly selected convenience sample (by walk past; the researchers positioned themselves at the Army mess buildings over 4 days and all soldiers who walked past were sampled) of 807 NZ Army personnel were included in this study. The single inclusion criterion was current membership of the NZ Army regular force; there was no filtering of participants based on anthropometric or anatomical characteristics. Participants were recruited from the 2 main military bases in NZ, and all measurements were completed on site. Approval for access was by verbal informed consent. Data were not collected for ethnicity, age, height, gender, or weight, as most of these 438 MILITARY MEDICINE, Vol. 176, April 2011

TABLE I. Data Collected from the 807 Members of the Regular Force NZ Army Based on Width, Circumference,, Arch Height, and size (US) (cm) Width (cm) Circumference (cm) Range 4 14 18.2 34.0 8.3 19.0 10.5 31.0 Mean (±SD) 9.80 (1.71) 26.28 (1.71) 10.33 (0.81) 25.31 (1.68) Data given are size/measurement range and mean (±SD) for all measurements. variables have been identified previously as nonsignificant factors in terms of injury occurrence, prevention, and treatment for the injuries of interest. 11 Although it was not known at the time of data collection that there would be ethnicity differences (and was therefore considered to not be relevant), such differences became apparent as a result of the study. METHOD A total of 807 NZ Army personnel were included in this investigation. Feet were measured with boots and socks off, while in a weight-supported (standing) position. The aim of the study was to create a representative distribution of foot anthropometric data for soldiers in the NZ Army. MATERIALS This study included the use of a standard seamstress tape measure (1.5 m) to take measurements of the feet and a standardized visual scale of arch height as used within the NZ Army equipment issue stores and is defined as follows: For high arches: 30% or less ground contact just under the metatarsal phalangeal joint; For medium arches: >30% to <55% ground contact just under the metatarsal phalangeal joint; For low arches: 55% or more ground contact just under the metatarsal phalangeal joint; These measurements were taken with participants standing upright with both feet planted at hip width apart. TABLE II. Arch Height Distribution Counts and Percentages from the 807 Members of the NZ Army Who were Included in the Study: Possible Range from Very High to Low Arch Height Number of Participants (%) Very High 0 High 31 (3.84) High Medium 29 (3.59) Medium 103 (12.76) Medium Low 94 (11.65) Low 550 (68.15) PROCEDURE Data collection took place over 1 week at the NZ Army s 2 main bases; measurements took approximately 8 minutes per participant and all data collection was completed by the lead author (Marian L. Baxter). No other anthropometric or participant data were obtained for 2 reasons: most variables have been previously identified as nonconfounding (specifically height, weight, and gender 11 ), also it would have prolonged the measurement time unnecessarily, as only foot data was of interest in the study. characteristics were collected from each participant while they stood upright on 2 bare feet. This included boot size, foot length (measured from the rear of the talus where it makes contact with the ground to the tip of the second toe), foot width (measured as the distance between the widest part of the foot lateral medial), foot circumference (the circumference of the foot when standing around the metatarsal tarsal joint), and arch height (according to the NZ Army s standardized measurement system: percentage of ground contact when standing). Measurements were taken from the participant s longest foot, using a seamstress tape measure. Data Analysis Data recorded during measurement sessions were collated and entered into excel spreadsheets (Microsoft) for analysis using descriptive statistics. Values obtained were subsequently compared with data for the NZ general population. RESULTS Data are presented in Table I as means and SDs for arch height; frequency data are presented as appropriate in Table II ; Graphically represented percentages across arch heights are shown in Figure 1 ; and NZ population percentages are shown in Figure 2. 12 Distributions indicate that the NZ Army soldiers have feet that are different to that of the general population. It was also found that some soldiers (approximately 50%) were wearing boots that did not fit because of limited size and width availability (Table III ): this was an unexpected finding. DISCUSSION This study aimed to collect normative data of anthropometric foot characteristics from a representative sample of soldiers from the NZ Army and to describe differences with data for the general population. The ultimate goal was to provide valid, accurate, and reliable data to inform production of appropriate and well-fitting footwear. The principal findings were that NZ Army personnel had notable differences in feet anthropometry compared to the NZ general population, specifically related to arch height distribution ( Figures 1 and 2 ). This could have been due to the greater proportions of Maori and Pacific Islanders within the Army compared to the general population, which is somewhat speculative, and based on anecdotal evidence of a higher prevalence of a flatter arch. MILITARY MEDICINE, Vol. 176, April 2011 439

(cm) of s Included in the Study ( n = 807) FIGURE 1. Histogram showing extrapolated arch height distribution of soldiers in the NZ army ( n = 807). FIGURE 2. Histogram showing extrapolated arch height distribution of the NZ general population. 12 Because of the limited research within NZ on anthropometric foot data, it is impossible to make further comparisons besides that of arch height distribution. It was also found that a proportion of the personnel tested (approximately 1 soldier in 6) could not be provided with a boot that fitted properly, apparently because of a limited width range of the current boot (see Table III ). The current issue boot 1 10.5 27.5 404 8 24.6 2 7.5 26.5 405 10.5 27.5 3 8.5 26.5 406 9.5 26.2 4 10.5 27.5 407 11 27.8 5 9.5 27 408 9.5 26.9 6 10.5 25.5 409 9 26.3 7 6 24.5 410 10.5 28 8 13 26 411 10.5 27.1 9 6.5 24 412 10 25 10 6.5 25 413 7.5 24.7 11 6 23.5 414 12 28 12 10 28 415 9.5 26.6 13 8 29 416 14 30.3 14 4 23.5 417 10 27.1 15 10.5 26 418 10.5 27.2 16 12.5 30.5 419 10.5 26.2 17 11.5 28.5 420 8.5 25.5 18 12.5 30 421 10 26.4 19 10 25.5 422 10 26.2 20 11 30 423 9.5 25.7 21 9.5 27 424 11 26.9 22 9.5 24.7 425 10 25.9 23 11 28 426 10.5 26.4 24 10.5 26.5 427 9.5 25.7 25 11 27 428 7 24.7 26 5.5 24 429 8.5 27.4 27 11.5 27.2 430 10.5 27.1 28 12 29 431 11.5 28.5 29 10 25 432 6 24.9 30 10 28.5 433 10.5 26.3 31 10 27.5 434 10 25.7 32 14 32 435 9.5 27.1 33 9 25 436 12.5 27.3 34 13 31 437 11.5 27.1 35 11 28.5 438 12 27.2 36 11.5 30 439 10 25.3 37 7.5 24.5 440 9 24.3 38 10.5 27 441 6 23.4 39 11 28.5 442 6 24.2 40 10 27.5 443 9.5 24.4 41 7 24 444 12 27.5 42 10 27 445 13 18.2 43 10 28.5 446 10.5 26.7 44 11.5 28.5 447 11 26.5 45 11.5 28 448 9.5 27.3 46 11 28.2 449 11 26.3 47 9 25.5 450 10.5 27.1 48 10 25.5 451 9.5 25.1 49 9 27.5 452 9.5 27.8 50 8 25 453 13 28.2 51 12 29.5 454 14 29.3 52 6.5 25 455 8.5 25.6 53 11 29.5 456 11 24.8 54 10.5 29 457 9 25.4 55 11 27 458 6 22.2 56 9.5 27 459 11 26.4 57 12 28.7 460 8.5 24.1 58 10.5 29 461 8.5 24.8 59 7.5 25.5 462 9.5 27.8 60 11 29.5 463 9 24.9 () 440 MILITARY MEDICINE, Vol. 176, April 2011

61 11 29 464 9 25 62 12 30 465 10.5 27.3 63 9 26.5 466 10.5 26.8 64 10 27.7 467 9.5 25.6 65 9.5 27 468 9.5 26.5 66 11 28.5 469 9.5 26 67 11 28.5 470 7 23.9 68 10.5 28.5 471 8 24.7 69 10 26.5 472 10.5 27.1 70 10 26.5 473 7.5 23.8 71 10.5 28.5 474 10 25.6 72 10 25.5 475 9.5 25.7 73 12 27.5 476 9.5 24.4 74 10 27 477 10 26.4 75 10.5 27 478 12 28.6 76 7 23.5 479 10.5 26.2 77 9 25 480 10 26.8 78 9.5 25.5 481 9.5 25.8 79 8.5 24.5 482 10 25.3 80 9.5 27 483 9 23.6 81 8 22.5 484 10 26.7 82 10 26 485 9 25.1 83 10.5 27 486 9 24.5 84 13 28.5 487 11 28.6 85 11 28 488 6 23.2 86 13 30 489 9.5 25.7 87 10 27.5 490 9.5 26.4 88 11 27 491 8.5 25.6 89 9.5 25.5 492 13 27.4 90 9 23.7 493 7 25.1 91 9 25.5 494 5 22.3 92 12 27.5 495 6 23.2 93 10.5 27.5 496 10 27 94 10.5 27 497 8.5 24.2 95 8.5 27 498 6 24.7 96 8.5 25.5 499 6 22.5 97 10.5 28 500 12 28.7 98 10 27 501 12 29.2 99 11 29 502 9 24.8 100 10 26 503 11 26.3 101 10 28 504 8.5 24.8 102 12 29 505 7.5 25 103 13 28 506 7 25.2 104 9.5 25.5 507 10.5 28.2 105 11.5 29 508 10 26.7 106 9 27 509 11.5 28.6 107 10 26.5 510 10.5 28.3 108 9 25.2 511 9 26.4 109 7 24 512 10 29.3 110 10.5 28.5 513 9.5 26.5 111 9 28 514 7 25.7 112 10.5 27 515 10.5 28.2 113 10 27 516 9.5 25.4 114 9.5 25.2 517 9.5 28.1 115 8 24.5 518 12 25.5 116 9.5 27 519 10.5 27.2 117 11.5 27.2 520 9 25.3 118 11.5 28 521 9.5 25.9 119 8 26 522 11.5 27.7 120 9.5 26.2 523 8.5 25.4 121 11 27 524 10.5 28.1 122 6 24 525 9 26.4 123 10.5 29 526 9.5 27.8 124 10.5 29 527 9 25.2 125 10.5 27.5 528 10 26 126 10.5 28.5 529 10.5 27.3 127 10.5 27.2 530 8.5 25.6 128 9.5 27.5 531 5 23.8 129 9.5 26 532 6 22.9 130 10.5 26.5 533 9 24.3 131 9.5 26 534 11.5 26.4 132 12 28 535 11.5 26.9 133 8 26 536 10.5 25.1 134 9 26 537 9 24.8 135 12 27.5 538 10 26.5 136 11 28.2 539 10.5 25.6 137 10.5 26.4 540 9.5 25.3 138 9.5 26.2 541 8 25 139 9 26.2 542 10 27.8 140 12 28.5 543 11 27.6 141 6 23.7 544 9.5 25.6 142 9 26 545 10 26.3 143 9 26.7 546 8.5 25.6 144 12 34 547 12 26.5 145 6 24 548 9 25.9 146 11 29 549 11 27.5 147 10 27.5 550 10.5 25.4 148 10 27 551 11.5 26.6 149 7 24.5 552 12 25.6 150 10 25.5 553 8 23.8 151 8.5 25 554 10 26.7 152 10.5 26.5 555 7.5 24.4 153 10.5 27.1 556 11.5 26.6 154 10.5 28.5 557 10.5 25 155 10 27.5 558 10 25.5 156 8.5 25.5 559 7.5 21.2 157 8 23.7 560 10.5 26 158 7.5 25.5 561 11.5 26.3 159 8 25.5 562 10.5 28.2 160 7.5 25.2 563 10 25.7 161 6.5 25.2 564 11 24.9 162 5.5 23.7 565 10.5 27 163 5 22.5 566 12 25.1 164 7.5 25.2 567 14 31.4 165 10.5 27.3 568 6 23 166 10 27.2 569 12 27.7 167 8 24 570 9.5 25 168 11 27.4 571 11 28 169 11 26.2 572 10 26.2 170 4 24.7 573 10 24.8 171 10 27 574 10.5 25.3 172 8 26 575 9.5 25 173 9 26 576 8.5 24.1 174 6 23.5 577 9.5 24.4 175 6 24.4 578 12.5 25.6 176 10.5 27.5 579 11.5 25.3 177 11 28 580 11 27.3 178 8 25.5 581 11 28 179 11.5 27.2 582 10.5 27.2 180 9 26.4 583 9.5 27.2 181 9 27.5 584 9.5 25.6 182 7 24.5 585 11.5 26.8 MILITARY MEDICINE, Vol. 176, April 2011 441

183 7.5 25 586 10 26 184 10 26 587 9.5 26.3 185 9 26.2 588 7 25.9 186 8.5 25.8 589 11 27.2 187 8 23.3 590 11 28.2 188 10.5 28.2 591 11 27.4 189 10 27.4 592 9.5 26.7 190 10 27 593 11.5 27.2 191 8 23.3 594 7.5 24.7 192 6.5 24.5 595 11 27 193 10.5 27.5 596 8 25 194 7 24 597 9.5 24.5 195 6 24.5 598 11.5 28 196 6 24.7 599 10 26.2 197 5 23.7 600 10.5 26.7 198 10.5 26 601 11 27.5 199 9 25 602 9 24.2 200 9 25.1 603 12 28.1 201 12 29 604 10.5 26.1 202 10.5 26.5 605 8.5 25.3 203 11.5 28.2 606 9.5 24.8 204 11.5 27.6 607 9.5 24.9 205 12 28.5 608 10.5 26.6 206 11 28.3 609 9 23.9 207 13 29 610 9 25.4 208 9 23.7 611 6 24 209 12 28.7 612 10.5 25.2 210 9 27 613 10 27 211 10 25.7 614 9 25.4 212 10 26.2 615 11.5 27.8 213 12 28.7 616 8.5 23.4 214 10.5 27.3 617 8.5 25.7 215 13 28.4 618 11 26.1 216 10.5 27.4 619 9 24.1 217 8 24.2 620 8.5 24.3 218 11.5 29.3 621 5 23.2 219 14 29.7 622 9 25 220 11 27.6 623 7 24.8 221 10 27 624 10 26.1 222 7 24.1 625 9.5 26.4 223 8.5 24.4 626 11 28 224 11.5 27.1 627 8.5 25 225 11.5 28.3 628 12 28.1 226 13.5 31 629 10 24.4 227 9.5 27.5 630 8 26.2 228 9.5 25 631 5 22 229 10.5 28.3 632 10 26.2 230 9 26.5 633 10.5 24.9 231 9 25.1 634 10 25.8 232 9 25.7 635 11 26.5 233 9.5 26.7 636 9.5 24.8 234 9.5 27 637 9 25.4 235 11.5 28.4 638 9.5 25.4 236 9.5 27.6 639 11 26.9 237 7 24.3 640 9.5 26.2 238 9 26.5 641 10 26.4 239 8 24.6 642 9 25.5 240 11 28.7 643 11.5 26.6 241 10 25.2 644 9.5 26.2 242 7 22.4 645 6.5 24.8 243 11 27.4 646 7 23 244 9 27 647 10.5 27.6 245 12 29 648 5 23 246 10.5 28.3 649 11.5 29 247 12 28.5 650 8 25 248 9.5 26.4 651 10 25 249 12 27 652 10 28 250 14 30.5 653 11 27 251 8.5 24.4 654 8.5 26 252 10.5 26.5 655 14 29 253 9.5 26.5 656 5.5 23 254 10.5 26.4 657 9.5 25.5 255 10.5 28 658 11 27.4 256 8.5 24 659 10 26.4 257 11 26.8 660 9.5 25 258 10 26.5 661 10 25.6 259 12 26.4 662 9 24.3 260 10.5 25.7 663 11 25.2 261 10.5 24.5 664 8 24.7 262 10.5 27.6 665 11 26.4 263 11.5 29.4 666 8.5 25.2 264 9.5 27 667 6.5 23 265 9.5 26 668 11 26.8 266 12 28 669 8.5 24.5 267 9.5 25.7 670 10 24.8 268 8 24.2 671 9.5 26.8 269 9.5 24.3 672 12.5 27.4 270 9 24.3 673 9.5 23.9 271 10 27.8 674 10 27.3 272 10.5 25.7 675 10 26.5 273 10 25.7 676 10.5 26 274 10 25.5 677 9.5 26.3 275 11.5 27.2 678 10 26.4 276 10 26.9 679 10 25.3 277 11 26.8 680 12 28.2 278 10 27.3 681 7 26 279 13 28 682 10.5 29.2 280 10.5 27.2 683 8 26.7 281 9.5 26.5 684 10.5 27.3 282 12 27.8 685 8 24.6 283 8.5 25.9 686 10.5 27.5 284 12 27.1 687 9.5 26.2 285 10.5 26 688 11 27.8 286 9.5 25.2 689 9.5 26.9 287 12.5 28.2 690 9 26.3 288 10 26.8 691 10.5 28 289 12 27.4 692 10.5 27.1 290 9 28 693 10 25 291 10 27.1 694 7.5 24.7 292 11.5 28.2 695 12 28 293 7.5 24.9 696 9.5 26.6 294 11 27.1 697 14 30.3 295 8 24.6 698 10 27.1 296 10.5 27 699 10.5 27.2 297 9 25.9 700 10.5 26.2 298 10.5 26.8 701 8.5 25.5 299 11.5 26.4 702 10 26.4 300 10.5 25.5 703 10 26.2 301 10 26.5 704 9.5 25.7 302 12.5 28.5 705 11 26.9 303 10 26.4 706 10 25.9 304 9 27.8 707 9 26.7 () 442 MILITARY MEDICINE, Vol. 176, April 2011

305 12 26.8 708 10 26.6 306 11 26.2 709 10 25.4 307 9 25.7 710 6 24.2 308 9 26.3 711 7.5 24.2 309 11 27.2 712 7 22.7 310 13 28 713 13 31.8 311 10.5 27.7 714 9.5 25.6 312 10 25.8 715 10.5 26.2 313 10.5 26.2 716 12 29.3 314 11 27.3 717 12 26.8 315 9.5 26 718 11 26.9 316 9.5 26.7 719 10 26.7 317 10 25.7 720 10 27.2 318 11.5 27.5 721 10.5 28.6 319 9.5 26 722 13 28.4 320 9.5 25.3 723 10 26.3 321 9 25.2 724 11.5 28.3 322 9 24.2 725 10.5 26.6 323 10 24.6 726 10.5 27 324 12 28 727 9 25.4 325 11 27.3 728 10 27.2 326 11 27 729 11 28.4 327 10.5 26.3 730 13 30.3 328 12 26.8 731 10 25.3 329 12.5 29.7 732 11.5 29.2 330 10.5 26.6 733 10.5 27.7 331 13 28.4 734 10 27.2 332 8 25 735 9 25.2 333 9 27 736 7.5 24.8 334 8 25.3 737 9.5 26 335 12 27.5 738 9 22.8 336 9 26.2 739 9.5 25.2 337 6.5 24.7 740 12.5 26.2 338 8 24.2 741 10 26 339 7 26.2 742 9.5 25.1 340 9.5 27.5 743 11 26.1 341 5.5 24.5 744 12 28.5 342 9 25.4 745 9 26.4 343 6 22.7 746 9 26 344 9.5 26.1 747 8 24.5 345 7 22.6 748 7.5 24 346 9 24.5 749 7 24.3 347 6.5 22.8 750 10 24 348 10 27.4 751 11 26 349 9.5 25 752 6 22 350 6.5 22 753 12.5 28.7 351 10 25.8 754 6 22.4 352 10 26.8 755 7 22.5 353 13 27 756 7 22.6 354 10.5 27.8 757 7 22.6 355 5 23.9 758 9.5 25.6 356 11 26.3 759 10.5 26.3 357 9 24.5 760 9.5 23.2 358 10.5 26.6 761 9.5 23.8 359 10.5 26.2 762 11 27 360 11 27.3 763 9.5 24.6 361 11 26.5 764 11 25.4 362 12 27.7 765 12 26.5 363 10 27.7 766 11 27.4 364 8.5 25.7 767 9 23.5 365 8 24 768 11 28 Those who were not wearing the correct boots are shown in italics. 366 10 25.5 769 11 26.4 367 11 27 770 11 26.2 368 10 25 771 11.5 29 369 13 27.6 772 10.5 26.8 370 10.5 26.3 773 10.5 25.4 371 9.5 25.9 774 6 22.9 372 11 26.8 775 11.5 28.3 373 5.5 23.5 776 9.5 26.3 374 8.5 24 777 10.5 26.5 375 5.5 23 778 10.5 27.3 376 9.5 25.5 779 11 27.4 377 11 27.4 780 8.5 25.9 378 10 26.4 781 12 29 379 9.5 25 782 9 26.3 380 10 25.6 783 10 26.5 381 9 24.3 784 5 23.1 382 11 25.2 785 10 26.8 383 8 24.7 786 12 29.2 384 11 26.4 787 10.5 25.9 385 8.5 25.2 788 10.5 26.5 386 6.5 23 789 11 27.2 387 11 26.8 790 9.5 26.1 388 8.5 24.5 791 8 24.7 389 10 24.8 792 9.5 25.3 390 9.5 26.8 793 9.5 26.5 391 12.5 27.4 794 9.5 23.7 392 9.5 23.9 795 10 26.4 393 10 27.3 796 11.5 25.8 394 10 26.5 797 5 22.9 395 10.5 26 798 11.5 26.8 396 9.5 26.3 799 9 24.5 397 10 26.4 800 9.5 25.7 398 10 25.3 801 12 29.3 399 12 28.2 802 7 23 400 7 26 803 14 28.3 401 10.5 29.2 804 9.5 26.4 402 8 26.7 805 10 25.3 403 10.5 27.3 806 9.5 25.2 is made and designed for soldiers who are of European descendent, who are anecdotally considered to have a characteristically thinner foot than the Maori or Pacific Island peoples. If this were indeed the case, a boot specifically designed with the unique characteristics found in the NZ Army soldier population could address some of the current problems with injuries. As seen in Table I, the range of foot sizes were US size 4 to 14, with mean and standard deviation of US size 9.8 and 1.7, respectively. This was expected, as information from army supply stores indicates that foot wear is ordered from US size 4 to US size 16, the most common size being a US size 10.5. The mean and standard deviation suggest that foot sizes tend to be towards the larger end of the scale. As the investigation was primarily to collect anthropometric data, boot size may seem to hold little relevance here. However, it is of particular relevance within the NZ Army as MILITARY MEDICINE, Vol. 176, April 2011 443

there is anecdotal evidence of limited width availability for army boots; collection of boot size data was to allow comparison with data for foot length to assess whether soldiers were wearing correct footwear based upon the measured lengths. It was found that an average of 1 in 7 soldiers was wearing a boot that was larger than required (in some cases up to 3 sizes too big) apparently to have a boot that was wide enough. This finding suggests that the current footwear supplied by the army is inappropriate for some soldiers. length ranged from 18.2 to 32 cm, with means and standard deviations of 26.3 cm and 1.7, respectively; these data are comparable to the data on boot size. However, the average length is slightly shorter than that required for the average boot size, which might be expected given that a proportion of the boots the soldiers are wearing is too big compared to their foot length. width ranged from 8.3 to 19.0 cm; corresponding values for mean and standard deviation were 10.3 cm and 0.8, respectively. No relevant data were available in current literature for comparison. circumferences ranged from 10.5 to 31.0 cm, with mean of 25.31 cm and standard deviation of 1.68. Arch height range ( Table II ) was compared to members of the NZ general public ( Figures 1 and 3 ). A visual comparison suggested that army personnel tended to have lower arches than the NZ general public. The apparent reason for this was the relative difference in the proportion of population accounted for by Maori and Pacific Islanders; the general population includes just over 15% Maori and Pacific Islanders, although comparative data for the NZ Army includes 30% (Dunn, personal communication). It is widely accepted that anthropometric differences between Europeans and Maori/ Pacific Islanders includes a tendency for lower arches, although there are no published data to confirm this. Practical Implications The current findings on foot anthropometric characteristics of NZ Army soldiers suggest that some of the prevalence of lower limb and lower back injury may be attributable to issue related to footwear. These data should also inform production of more suitable footwear; knowledge of the tendency of lower arch height and need for a wider fit are especially important. Perhaps the most important finding was that a proportion of soldiers were wearing boots too big to have a suitable width ( n = 463, Table III ). Wearing boots that are too big has been proven to increase the risk of overuse injury. 13 Given that the most common injury within the NZ Army is overuse injury of the lower limb and lower back and the relation to inappropriate footwear, 13 it is clear that this issue needs to be addressed. More research is needed in this area to confirm and extend the findings of this study. It is suggested that more research would enable the NZ Army to better improve the currently issued equipment. FIGURE 3. Measurements taken from the foot; Top: foot length and width were measured, along with arch height (while standing). Arch height was measured as the percent ground contact under the arch. Bottom: the circumference of the metatarsal phalangeal joint was measured. Future Directions A major issue faced in this study was the lack of comparative data, which did not allow firm conclusions to be made on the findings. More research is necessary to provide comparative and baseline data sets. A similar study completed across a larger sample size is warranted. Future research should focus on the soldiers who were seen to have most problems (apparently Maori and Pacific Islanders). In addition, a matched sample of the population (matched by ethnicity) should be undertaken. This will add further support to the findings of this study and clarify whether particular demands of being in the NZ Army has an effect on foot anthropometry. It has been strongly recommended that boots should be made available in sufficient width and length ranges to provide a boot that fits to all soldiers. To achieve this, further investigation is warranted as to the specific range of widths and lengths required within the soldier population, and boot manufacturers need to be provided with these demographics to ensure that availability needs are met. 444 MILITARY MEDICINE, Vol. 176, April 2011

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