Injury is a major problem for participants in collision sports. North American football, Rugby Union, Rugby League, Australian Rules football, and ice hockey are all beset by a high incidence of personal injury. Because collision-style contact is an integral part of these sports, attention has focused on the use of protective equipment to dissipate impact forces and offer support to vulnerable body structures.
A diverse range of personal protective equipment is used in collision sports, ranging from lightweight items like support sleeves and taping of body joints to the hard-shell helmets and bulky body pads required in North American football. Most usage of protective equipment in collision sports arises from regulatory mandate. There are little published data on voluntary usage of protective equipment in collision sports, with the exception of mouthguard use in Rugby Union and Rugby League players (7,9–11,21,22,30).
This paper presents data on the level of protective equipment usage in a cohort of New Zealand Rugby Union players. Variation of usage within individuals and variation in usage patterns by position and grade are described. Self-reported reasons for using protective equipment and an analysis of injury history as a predictor of equipment usage are also presented. At the time these data were collected, the sport’s national officiating body, the New Zealand Rugby Football Union (NZRFU), did not require the wearing of any item of protective equipment, and the individual athlete was largely free to select what protective equipment s/he would wear, within the confines of the rules of the game. Mouthguard use was promoted, but not mandated, by the NZRFU.
This study utilized data from the Rugby Injury and Performance Project (RIPP), a prospective cohort study of Rugby Union players in Dunedin, New Zealand. A detailed description of the study design and methods has been published elsewhere (31). Players initially participated in a preseason assessment that included an extensive questionnaire and a physical assessment. The cohort was subsequently followed over the course of the 1993 competitive club season. Each week, cohort members were telephoned and interviewed about their exposure to rugby and usage of protective equipment during the previous week. Weekly follow-up over the season was 90% complete (31). Before the start of data collection, the RIPP protocol was reviewed and approved by the Otago Area Health Board Ethics Committee. Informed written consent was obtained from all study participants.
Assessment of equipment usage.
Protective devices and equipment were defined as the following items: mouthguard, shin guards, padded headgear, taping of joints, head tape, support sleeves, and grease. The padded headgear typically used in New Zealand rugby is designed to protect the crown and the top of the head (32). It is constructed from fabric or leather, contains strips of impact-absorbing material up to 10 mm in depth, and has neither a hard outer shell nor a face mask. Taping typically involves the application of adhesive tape, sometimes with strips of cloth, to body joints. Taping affords additional support to the joint and limits the range of motion (1,5). In addition to taping joints, rugby players sometimes also apply adhesive tape and/or cloth strips to the head, for the purpose of protecting the ears from hematoma and other injury. Although the materials used are similar, joint taping and head taping seek to protect two very different classes of anatomical structure and therefore are treated as distinct items for the purposes of this study. Support sleeves are used to support body joints and insulate muscular areas. Grease is also sometimes applied to body surfaces, in part to make it harder for opponents to grasp them. The equipment items studied fall into two distinct groups: passive, extrinsic countermeasures (mouthguards, shin guards, headgear, and head tape) and active, intrinsic countermeasures (joint taping, support sleeves, and grease). Equipment items in the former category prevent injury by absorbing and dissipating external impact forces, whereas items in the latter group prevent injury by influencing the mobility and/or sensorimotor behavior of one or more body structures.
At the preseason assessment, participants were asked what equipment or devices they had used in their previous season of rugby and why they had used those items. In response to the query, “Did you use this equipment ...,” participants could check multiple responses from five precoded options: to prevent injury, under coach’s advice, under medical advice, due to a past injury, to improve rugby performance, and because everyone uses it. A write-in space was provided for additional responses. Then, in each week of in-season follow-up, participants were telephoned and asked the following question: “Did you use any protective gear or strapping during team practices or games last week?” Players were also interviewed about their active participation in rugby (number of games and practices) and injury experience (diagnosis, activity at time of injury, medical treatment sought) during the previous week.
Assessment of injury history.
Three aspects of injury history were examined to quantify its influence on protective equipment usage: injury in the previous season, preseason injury status, and the cumulative frequency of in-season injury. Previous season and preseason injuries were self-reported by the athlete on the preseason questionnaire. An injury in the previous season was defined as any injury resulting from rugby participation in the 12 months before the start of the 1993 season, which prevented the player from participating in at least one game, or at least two practices, or required medical attention. Athletes were asked to recall all injuries that met these criteria as part of the preseason questionnaire and were provided with a list of 14 common rugby injuries as an aid to recall. A write-in space was provided for other injuries. Preseason injury was defined as any injury that the player reported was currently affecting his or her ability to train at the time the preseason questionnaire was completed.
In-season injuries were defined as any injury resulting from rugby participation that required medical attention or caused the player to miss a scheduled game or team practice. Data on in-season injuries were obtained during the weekly follow-up interviews. The cumulative frequency of in-season injury was the total number of injuries sustained in the season up to, and including, the previous week of follow-up (i.e., the cumulative count, for each player-week of follow-up, of the number of in-season injuries, lagged 1 wk). This time-dependent variable increased during the course of the season for those participants sustaining one or more injuries and was zero for those who sustained no injuries during the season.
Grade and position categories.
A number of participants competed in more than one grade (5.4% of player-weeks) or played in more than one position (17.3% of player-weeks) during the course of the season. For the purposes of analysis, the most frequent grade and position over the course of the season for each player was used. Data on playing position were unavailable for one participant. Playing positions were grouped into the following categories:
Front row: left prop, right prop, and hooker (ball-winning players, typically of large physique).
Locks: left lock and right lock (support for the front row, also typically of large physique).
Loose forwards: left flanker, right flanker, and number eight (move the ball and feed it to the backs).
Inside backs: halfback and first-five-eighth (receive ball from the forwards, will either kick the ball, run the ball at the opponents, or pass the ball out to the other backs, typically more slightly built).
Center backs: second-five-eighth and center (run the ball at the opponents or pass the ball).
Outside backs: left wing, right wing, and full back (wings play wide and typically have good acceleration. Fullbacks are typically the last line of defense and serve as an overlapping man on offense).
In general, backs are involved in tackling and being tackled while on the run, whereas forwards are involved in numerous low-speed contacts at a wide range of body sites. Forwards tend to be more massive than backs (25).
The RIPP cohort included players from a wide range of levels of competition, namely, Senior A, Senior B, Women, Colts, Schoolboys, and Schoolgirls grades. Senior A and Senior B are the two highest grades of male competition. For the purposes of this analysis, one player who played Senior Reserve was included in the Senior B group (the next highest level of competition). Colts is the highest level of junior development and is open to players under the age of 21 yr. The Schoolboys group comprises players in the Under 19 and Under 18 age grade competitions. It included 40 players who competed in these grades under the auspices of a high (secondary) school team and 12 players who played on club teams. All schoolgirls competed on school teams.
The main outcome measure of interest was the percentage of player-weeks for which each equipment item was used. This was calculated as the weighted sum (over the cohort) of player-weeks of use for each item, divided by the weighted sum (over the cohort) of player-weeks of active participation in rugby, times 100, i.e.,
where xij = weeks of active participation in rugby for which participant i used item j;
ni = weeks of active participation in rugby for participant i;
wi = weight for participant i, proportional to
A player was considered to have participated actively in rugby in a given week if s/he had participated in at least one team practice or game in that week. Length of season, length of follow-up, and total weeks of active participation in rugby varied between players. To prevent players with greater participation and more complete follow-up from exerting undue influence on the outcome measure, the usage percentage was inversely weighted by the number of weeks of active participation in rugby (wi −1). To facilitate interpretation, usage percentages were categorized as follows: never used (0%), seldom used (1–29%), sometimes used (30–69%), and frequently used (70–100%). Ninety-five percent confidence intervals (95%CI) were calculated for all usage percentages.
For each of the protective equipment items, usage was highly correlated within individuals. Variance inflation factors for the overall usage percentages ranged from 6.8 for mouthguards to 11.3 for padded headgear (the variance inflation factor, or “design effect,” indicates the degree of clustering, with 1.0 being no effect). SUDAAN software was used to adjust the standard errors of the usage percentages for the inflation in variance due to correlation within individuals (29). Strength of association between previous injury and protective equipment usage was assessed using Pearson’s chi-square test, and the Mantel-Haenszel chi-square test was used to examine this association while controlling for grade and position (23).
A total of 356 participants were enrolled in the RIPP cohort. Twenty-nine individuals were excluded from the analysis presented in this paper for the following reasons: did not complete the full preseason assessment (N = 10), not followed at all during the season (N = 8), followed for less than 50% of the season (N = 4), never participated in any rugby games or team practices (N = 3), and mainly participated in social games with limited exposure to competitive club play (N = 4). The remaining 327 players (240 male and 87 female) accumulated a total of 5633 player-weeks of follow-up and participated in at least one team practice and/or game in 4703 (83%) of these player-weeks.
The demographic characteristics of the overall cohort have been reported previously (2), and the subset analyzed here was very similar. A high proportion were full-time students enrolled at a secondary or tertiary educational institution (65.0%). The mean age was 20.3 yr and ages ranged from 14 to 39 yr. The male players were considerably more experienced in the game than their female counterparts; this was the first season of participation in organized rugby for 45.3% of the women and 100.0% of the schoolgirls (1993 was the first season that the schoolgirls grade was offered in Dunedin). By contrast, this was the first season of organized rugby for only two of the male players (both were schoolboys). Among those participants who had played the game previously, the mean number of consecutive years of play was 5.9 (male: 6.4; female: 3.0). Rugby was the self-reported major sport for 92.9% of the male players and 41.9% of the female players.
Mouthguards were the most commonly used item of protective equipment. Usage ranged from 88.6% of player-weeks for Senior A forwards to 56.2% of player-weeks for Schoolgirl backs, with an average across all grades and positions of 64.9%. Taping, padded headgear, and grease were the next most commonly used items (10–25% usage), whereas shin guards, support sleeves, and head taping were all used less than 10% of the time. Overall, study participants used at least one item of protective equipment in 75.8% of player-weeks. When mouthguards were excluded from analysis, the usage dropped to 50.3% of player-weeks.
Equipment usage by grade and position.
There were important variations in equipment usage by grade and position (Tables 1A). Usage of protective devices and equipment was higher in forwards than in backs, with the exception of support sleeves (4.8% of player-weeks for forwards and 11.4% for backs). Backs were relatively homogeneous in terms of equipment usage. Forwards’ usage, on the other hand, varied considerably from one position to another. Grease and head taping were mainly used by locks, whereas front row players were the highest users of mouthguards and shin guards. Loose forwards were the highest users of padded headgear.
In general, female players had markedly lower usage of protective devices and equipment than their male counterparts. This was particularly true for padded headgear and grease, which had almost zero usage in women players. Within the male grades, the highest levels of mouthguard, shin guard, and body taping usage were observed in the Senior A players. Schoolboys’ usage of padded headgear and grease exceeded that of any other grade.
To learn more about taping practices, respondents were asked what sites they taped and who performed the taping. This information was obtained during the preseason assessment and relates to taping practices in the player’s most recent rugby season (the most recent season was the previous calendar year, winter 1992, for 94.1% of those who responded). The most commonly taped body sites were the ankle, thumb, and knee (Tables 1B). Of those players who used taping, 58.2% taped a lower limb and 48.8% taped an upper limb. The taping was commonly performed by either a team physiotherapist (42.4%), the individual player (40.4%), or a team trainer or medic (22.7%) (the player could indicate more than one body site or person; therefore, these percentages do not sum to 100%).
Variation in equipment usage.
Users of protective equipment exhibited considerable variation in their week-to-week usage patterns (Table 2). Mouthguards were the only equipment item with a large number of frequent users. Shin guards and padded headgear had similar proportions of users in the seldom, sometimes, and frequent categories. The majority of grease, taping, support sleeve, and head tape users wore the items sporadically (more than 50% of users used the item for less than 30% of the season).
Injury history as a predictor of equipment usage.
The strength of association between injury history and protective equipment usage was examined. Grade and position were strong potential confounders in this analysis, because they are associated with both equipment usage and injury experience. We controlled for them using the Mantel- Haenszel procedure. However, because both grade and position may also be influenced by injury history, controlling for their influence potentially underestimates the true association between injury history and equipment usage. For this reason, the unadjusted and the adjusted P-values should both be interpreted with some degree of caution.
A history of rugby injury (either head or nonhead) in the previous rugby season was strongly associated with increased use of headgear. After adjusting for grade and position, previous season injury failed to predict usage for any other equipment item (Tables 4A and 4B). Self-reported presence of a current injury at the start of the season was a predictor of taping and support sleeve usage, and the cumulative frequency of in-season injury was associated with headgear and taping usage, after adjustment for grade and position.
Reasons for using protective equipment.
At the preseason assessment, players were asked to identify the reason(s) why they used protective equipment. This analysis was limited to players who had previously competed in organized rugby and reported using one or more items of protective equipment in their most recent season (N = 252). Participants could identify as many reasons as they felt appropriate. The two most commonly cited reasons were to prevent injury (70.2%) and because of a past injury (65.5%). Medical advice was cited by 25.0% of players; a further 12.7% used equipment to improve their rugby performance, and 4.4% cited coaching advice. Only two participants (0.8%) cited peer pressure, and only eight (3.2%) did not identify at least one of the health/injury responses (injury prevention, past injury, or medical advice) as a reason for using protective equipment.
This study of rugby players in Dunedin, New Zealand, identified high levels of voluntary mouthguard use and low to moderate levels of usage for other equipment items. Grade, position, and injury history all played an important role in determining the type of protective equipment used and the frequency of usage. The most commonly reported reason for using protective equipment was to prevent injury. Use of protective equipment was higher in those players who were at greater risk of injury, such as forwards, male players, and the senior grades. The fact that players demonstrate significant levels of voluntary usage, coupled with high toll of injury in this sport (3,12,15,16,27), suggests that health professionals should consider advocating for the further changes to the rules of the game, with a view to increasing the range of protective equipment that is permitted (18,20). Further research into the effectiveness of such equipment is also warranted.
Despite the importance of protective equipment in preventing sports injury, there are relatively few reports in the literature describing usage patterns in collision athletes. Almost all research has focused on the use of mouthguards in collision sports (7–11,13,21,22,24,26,28,30) with particular emphasis on Rugby Union (7–11,13,21,22,30). Other items of protective equipment have been largely ignored. This study used an inclusive definition of protective equipment in order to capture the variety of equipment items used in modern rugby, and, to the best of our knowledge, this is the first comprehensive study describing the full range of protective equipment used in a population of rugby athletes.
The weekly telephone interview method utilized in this study minimized the potential for recall bias. During the season, study participants were never asked to recall information over a time period of greater than 1 wk. This approach represents a significant methodologic advance over previous studies, almost all of which have utilized a cross-sectional design (7–11,13,21,22,30). A significant degree of week-to-week variation in usage was observed in this study (Table 3), and this may, to some extent, be typical of voluntary usage of protective and safety devices in general. The presence of this weekly variation calls into question the reliability of the cross-sectional studies (7–11,13,21,22,30) and studies that have relied on the ability of the athlete, postseason, to self-report accurate usage data for the season (4).
The high level of voluntary mouthguards usage is indicative of a considerable level of player support for this item’s role in the game. This is also consistent with the previous research, which has found that a majority of players prefer to play with a mouthguard and support mandatory usage for adult players (7–11,30). A recent review of the literature on mouthguards in rugby concluded that there was strong evidence for the effectiveness of mouthguards in preventing dental and other orofacial injuries and that, in general, the majority of Rugby Union players surveyed in the literature wore a mouthguard on a “regular” basis (6). The proportion of players using a mouthguard “regularly” ranges from 53% for Senior grade players in Southern England (21) through to 96% for Australian club players (7). Interpretation of these studies is hindered by the fact that few of them have explicitly defined “regular” usage. Nevertheless, our finding that 59% of players wore a mouthguard for 70% or more of the season appears to be consistent with the published literature and indicative of a general acceptance by players of their role in the game of rugby. Subsequent to the collection of the data reported in this study, the NZRFU mandated mouthguard use at all levels of the sport in New Zealand.
The lower usage of protective equipment in female players may, in part, be due to differences in the style of play. Women’s rugby has only recently become an organized part of the sport, and, in general, the momentums and impact forces generated in the women’s game are lower than those in the male game (3,25). In addition, rugby was a secondary sport for nearly 60% of the women, and lack of familiarity with the protective equipment, and the cost of purchasing it, may initially discourage those who are new to the game from using protective equipment.
The finding that equipment usage is higher among those at greatest risk of injury has implications for future studies of protective equipment and injury. Previous injury is an important predictor of injury risk in athletes (17), and, because injury history is an important predictor of usage for some items, any epidemiologic study of the effectiveness of protective equipment in preventing injury must seek to control for the effect of injury history on both equipment usage and injury risk. In addition, there is a strong potential for bias in longitudinal studies where the outcome of interest (injury) influences the main study variable (protective equipment usage) at subsequent time points (19). In this study the use of taping, in particular, demonstrates the potential for this bias. Taping is used in rugby for two reasons: prophylactic application in an attempt to prevent injury and stabilization of a damaged joint after injury. Application of tape for the latter purpose probably explains a portion of the week-to-week fluctuation in usage and probably accounts for the observed association with injury history. Unfortunately, we lack week-to-week data on the specific reason for taping (prophylactic versus past injury).
Rugby Union involves significant transfers of force between players on the field of play but provides minimal protection to the participants. The physically demanding nature of the sport is in part maintained through the rules of the game, which impose strict limits on the protective equipment items that can be worn. Hard-shell helmets and padding at most body sites is expressly forbidden by the International Rugby Board (IRB). Recent rule changes have permitted the use of soft, thin (<1 cm) padded headgear and thin (<1 cm) shoulder pads.
The popular concept that rugby players view protective equipment with a degree of disdain gains credibility mainly from the relatively modest items that are legally permitted in the game. However, our finding that the cohort members used at least one item of protective equipment for about 75% of the season (50% if mouthguards are excluded) is in contrast to the widespread notion that rugby players largely eschew protective equipment. The high toll of injury associated with the sport (3,12,15,16,27) suggests that the possibility of updating the rules on protective equipment, while still maintaining the intensity, integrity, and character of the modern game, needs to be carefully investigated (18,20).
Cohort members exhibited a surprising degree of week-to-week variation in their usage of protective equipment. Use of protective equipment was highest in those players who were at the greatest risk of injury, namely, forwards, male players, and those in the senior grades. Because of this, and because injury history is an important predictor of usage for some items, epidemiologic studies of protective equipment effectiveness in preventing injury must control for injury history. The high voluntary usage of mouthguards is indicative of a strong base of player support for their usage.
The Rugby Injury and Performance Project was funded through a grant from the Accident Compensation Corporation of New Zealand to the University of Otago Injury Prevention Research Unit. The University of Otago Injury Prevention Research Unit is jointly funded by the Accident Compensation Corporation and the Health Research Council of New Zealand. The preparation of this manuscript was supported by University of North Carolina Injury Prevention Research Center. The University of North Carolina Injury Prevention Research Center is supported by a grant (R49/CCR402444) from the National Center for Injury Prevention and Control, Centers for Disease Control and Prevention. We acknowledge the invaluable support and assistance of the New Zealand Rugby Football Union, the Otago Rugby Football Union, the RIPP advisory board, the study interviewers, and the players who participated in the study. Thanks to Shrikant I. Bangdiwala, Ph.D., Frederick O. Mueller, Ph.D., Carol W. Runyan, Ph.D., and Carl M. Shy, M.D., Dr.P.H., for their comments on earlier drafts of this manuscript.
Address for correspondence: Stephen W. Marshall, Ph.D., Injury Prevention Research Center, CB#7505, Chase Hall, University of North Carolina, Chapel Hill, NC 27599-7505; E-mail: SMarshall@ Unc.Edu.
1. Beynnon, B. D., and P. A. Renstrom. The effect of bracing and taping in sports. Ann. Chir. Gynaecol. 80: 230–238, 1991.
2. Bird, Y. N., A. E. Waller, and D. J. Chalmers. The New Zealand rugby injury and performance project: playing experience and demographic characteristics. J. Phys. Educ. N. Z. 28: 12–16, 1995.
3. Bird, Y. N., A. E. Waller, S. W. Marshall, D. J. Chalmers, J. C. Alsop, and D. F. Gerrard. The New Zealand rugby injury and performance project: V. Descriptive epidemiology of a season of rugby injury. Br. J. Sports Med. 32: 319–325, 1998.
4. Blignaut, J. B., I. L. Carstens, and C. J. Lombard. Injuries sustained in rugby by wearers and non-wearers of mouthguards. Br. J. Sports Med. 21: 5–7, 1987.
5. Callaghan, M. J. Role of ankle taping and bracing in the athlete. Br. J. Sports Med. 31: 102–108, 1997.
6. Chalmers, D. J. Mouthguards: protection for the mouth in Rugby Union. Sports Med. 25: 339–349, 1998.
7. Chapman, P. J. Orofacial injuries and mouthguards: a study of the 1984 Wallabies. Br. J. Sports Med. 19: 93–95, 1985.
8. Chapman, P. J. Players’ attitudes to mouthguards and prevalence of orofacial injuries in the 1987 U.S. rugby football team. Am. J. Sports Med. 17: 690–691, 1989.
9. Chapman, P. J. Orofacial injuries and international rugby players’ attitudes to mouthguards. Br. J. Sports Med. 24: 156–158, 1990.
10. Chapman, P. J. Attitudes to mouthguards and prevalence of orofacial injuries in international rugby: a study of the 1990 Wallabies. Aust. J. Sci. Med. Sport 23: 113–115, 1991.
11. Chapman, P. J., and B. P. Nasser. Attitudes to mouthguards and prevalence of orofacial injuries in four teams competing at the second Rugby World Cup. Br. J. Sports Med. 27: 197–199, 1993.
12. Clark, D. R., C. Roux, and T. D. Noakes. A prospective study of the incidence and nature of injuries to adult rugby players. S. Afr. Med. J. 77: 559–562, 1990.
13. Davies, R. M., D. Bradley, R. W. Hale, W. R. Laired, and P. D. Thomas. Prevalence of dental injuries in rugby players and their attitude to mouthguards. Br. J. Sports Med. 11: 72–74, 1977.
14. De Wet, F. A., M. Badenhorst, and L. M. Rossouw. Mouthguards for rugby players at primary school level. J. Dent. Assoc. S. Afr. 36: 249–253, 1981.
15. Edgar, M. Tackling rugby injuries. Lancet 345: 1452–1453, 1995.
16. Garraway, W. M., and D. A. D. MacLeod. Epidemiology of rugby football injuries. Lancet 345: 1485–1487, 1995.
17. Garrick, J. G., and R. K. Requa. Role of external support in the prevention of ankle sprains. Med. Sci. Sports 5: 200–203, 1973.
18. Gerrard, D. F. The use of padding in rugby union: an overview. Sports Med. 25: 329–332, 1998.
19. Greenland, S. Introduction to regression modelling. In: Modern Epidemiology, 2nd Ed., K. J. Rothman and S. Greenland (Eds.). Philadelphia: Lippincott-Raven, 1998, pp. 401–432.
20. Hume, P. A., and D. F. Gerrard. Effectiveness of external ankle support: bracing and taping in rugby union. Sports Med. 25: 285–312, 1998.
21. Jennings, D. C. Injuries sustained by users and non-users of gum shields in local Rugby Union. Br. J. Sports Med. 24: 159–165, 1990.
22. Kay, E. J., P. Kakarla, D. A. D. MacLeod, and T. P. L. McGlashan. Oro-facial and dental injuries in club Rugby Union players. Br. J. Sports Med. 24: 271–273, 1990.
23. Mantel, N., and W. Haenszel. Statistical aspects of the analysis of data form retrospective studies of diseases. J. Natl. Cancer Inst. 22: 719–748, 1959.
24. Nowjack-Raymer, R. E., and H. C. Gift. Use of mouthguards and headgear in organized sports by school-aged children. Public Health Rep. 111: 82–86, 1996.
25. Quarrie, K. L., P. Handcock, A. E. Waller, D. J. Chalmers, M. J. Toomey, and B. D. Wilson. The New Zealand rugby injury and performance project: III. Anthropometric and physical performance characteristics of players. Br. J. Sports Med. 29: 263–270, 1995.
26. Rodd, H. D., and D. J. Chesham. Sports-related oral injury and mouthguard use among Sheffield school children. Community Dent. Health 14: 25–30, 1997.
27. Roux, C. E., R. Goedeke, G. R. Visser, W. A. Van Zyl, and T. D. Noakes. The epidemiology of schoolboy rugby injuries. S. Afr. Med. J. 71: 307–313, 1987.
28. Seals, R. R., R. M. Morrow, W. A. Kuebker, and W. D. Farney. An evaluation of mouthguard programs in Texas high school football. J. Am. Dent. Assoc. 110: 904–909, 1985.
29. Shah, B. V., B. G. Barnwell, and G. S. Bieler. Sudaan User’s Manual, Release 7.0. Research Triangle Park, NC: Research Triangle Institute, 1996, pp. 86–106, 135–149.
30. Stokes, A. M., and P. J. Chapman. Mouthguards, dental trauma and the 1990 All Blacks. N Z J. Sports Med. 19: 66–67, 1991.
31. Waller, A. E., M. Feehan, S. W. Marshall, and D. J. Chalmers. The New Zealand rugby injury and performance project: I. Design and methodology of a prospective follow-up study. Br. J. Sports Med. 28: 223–228, 1994.
32. Wilson, B. D. Protective headgear in Rugby Union. Sports Med. 25: 333–337, 1998.
Keywords:© 2001 Lippincott Williams & Wilkins, Inc.
SPORTS INJURY; PROTECTIVE DEVICES; MOUTH PROTECTORS; CONTACT SPORTS