Mouthguards in sport activities : history, physical properties and injury prevention effectiveness

Three systematic reviews were conducted on: (i) the history of mouthguard use in sports; (ii) mouthguard material and construction; and (iii) the effectiveness of mouthguards in preventing orofacial injuries and concussions. Retrieval databases and bibliographies were explored to find studies using specific key words for each topic. The first recorded use of mouthguards was by boxers, and in the 1920s professional boxing became the first sport to require mouthguards. Advocacy by the American Dental Association led to the mandating of mouthguards for US high school football in the 1962 season. Currently, the US National Collegiate Athletic Association requires mouthguards for four sports (ice hockey, lacrosse, field hockey and football). However, the American Dental Association recommends the use of mouthguards in 29 sports/exercise activities. Mouthguard properties measured in various studies included shock-absorbing capability, hardness, stiffness (indicative of protective capability), tensile strength, tear strength (indicative of durability) and water absorption. Materials used for mouthguards included: (i) polyvinylacetate-polyethylene or ethylene vinyl acetate (EVA) copolymer; (ii) polyvinylchloride; (iii) latex rubber; (iv) acrylic resin; and (v) polyurethane. Latex rubber was a popular material used in early mouthguards but it has lower shock absorbency, lower hardness and less tear and tensile strength than EVA or polyurethane. Among the more modern materials, none seems to stand out as superior to another since the characteristics of all the modern materials can be manipulated to provide a range of favourable characteristics. Impact studies have shown that compared with no mouthguard, mouthguards composed of many types of materials reduce the number of fractured teeth and head acceleration. In mouthguard design, consideration must be given to the nature of the collision (hard or soft objects) and characteristics of the mouth (e.g. brittle incisors, more rugged occusal surfaces of molars, soft gingiva). Laminates with different shock absorbing and stress distributing (stiffness) capability may be one way to accommodate these factors.Studies comparing mouthguard users with nonusers have examined different sports, employed a variety of study designs and used widely-varying injury case definitions. Prior to the 1980s, most studies exhibited relatively low methodological quality. Despite these issues, meta-analyses indicated that the risk of an orofacial sports injury was 1.6-1.9 times higher when a mouthguard was not worn. However, the evidence that mouthguards protect against concussion was inconsistent, and no conclusion regarding the effectiveness of mouthguards in preventing concussion can be drawn at present. Mouthguards should continue to be used in sport activities where there is significant risk of orofacial injury.     

The effect of wrist guards on bone strain in the distal forearm.

There are increasing epidemiologic and biomechanical data suggesting that wrist guards are effective in preventing wrist injuries in snowboarders and in-line skaters. However, there have been few studies designed to determine how they function. In this study we explored the load-sharing function of wrist guards at subfailure loading levels. To do so, we measured bone strain in the distal radius, distal ulna, and midshaft of the radius in cadaveric forearms with and without two types of commercially available wrist guards. We also measured construct stiffness and energy absorption during testing. Our most significant findings were that dorsal and volar distal radius bone strain were reduced with both wrist guards, and wrist guards increased energy absorption. We also found a reduction in dorsal distal ulnar bone strain, but only with the one guard in which the volar plate was elevated off the heel of the hand. In our loading configuration, wrist guards did not increase bone strain at the radial midshaft. These findings provide insight into how wrist guards protect the wrist: during low-energy falls they function partly by load-sharing, as well as by absorbing impact energy.     

Application of a standard test to the in vitro performance of mouthguards

OBJECTIVE: To use a simulated upper jaw made from a rubber arch containing replaceable ceramic teeth and a renewable composite ceramic jawbone to compare the effectiveness of seven custom made mouthguard designs and a "boil and bite" mouthguard. METHODS: Following an earlier development of a standard impact test using a selection of projectile shapes and energies, the most sensitive conditions were selected. These were then applied to a series of six guards constructed in ethylene vinyl acetate and styrene butadiene. The guards were constructed to reflect possible variations in both design and materials. RESULTS: Significant differences between the mouthguard performances were observed in response to the impact conditions selected. All the custom made designs gave better performance than the "boil and bite" mouthguard. CONCLUSIONS: The differences observed indicated that the standard test should be sensitive enough to be used as an assessment procedure for the approval of the manufacture of these safety devices. A sequence of tests on eight identical mouthguards selected from a batch of 12, based on the best design, gave remarkably consistent results, indicating that both the manufacturing technique and the test method are reliable. The features of the best design should be incorporated into the current "best practice" for the construction of these devices.


     

Transient forces generated by projectiles on variable quality mouthguards monitored by instrumented impact testing

OBJECTIVES: (a) To determine the force-time trace that occurs when a spring mounted simulated upper jaw is impacted; (b) to examine if mouthguards of variable quality have significant influence on such force-time traces; (c) to attempt to relate physical events to the profile of the force-time traces recorded. METHODS: A simulated jaw, consisting of ceramic teeth inserted into a hard rubber arch reinforced with a composite jawbone, was fitted with various mouthguards as part of a previous round robin study. A clinical assessment distinguished good, bad, and poor mouthguards, and these were each fitted to the jaw, which was then submitted to instrumental impact tests under conditions expected to produce tooth fractures. The force-time trace was recorded for such impact events. RESULTS: The spring mounting method caused two distinct peaks in the force-time trace. The initial one was related to inertia effects and showed an increase in magnitude with impactor velocity as expected. The second peak showed features that were related to the differences in the mouthguards selected. CONCLUSIONS: The use of a force washer within a conical ended impactor enabled force-time traces to be recorded during the impact of a spring mounted simulated jaw fitted with mouthguards of variable quality. The spring mounting system causes an initial inertial peak followed by a second peak once the spring mount has fully compressed. Good fitting guards, which keep most teeth intact, result in high stiffness targets that in turn generate high reaction forces in the impactor. If the spring mounting is omitted, the two peaks are combined to give even higher reaction forces. The force-time trace offers some potential for assessing both overall mouthguard performance and individual events during the impact sequence. Mouthguards with good retention to the jaw remained attached during the impact event and helped to preserve the structural integrity of the target. This in turn developed high forces in the second part of the force-time trace. Guards that detached during impact and allowed tooth fractures showed lower forces in the second part of the test. The force profile measured offered some quantitative support to, and agreement with, the observed clinical quality of the mouthguards.     

Effect of mouthguards on the transmission of force across the human jaw.

OBJECTIVE: To determine if impact responses (stiffness and damping values) of the jaw and neck are significantly different between mouthguards of varying material and manufacturing properties, in controlled conditions involving specified upper limb orientation and applied loading. DESIGN: Quasi-experimental design. SETTING: Simon Fraser University biomechanical laboratory. PARTICIPANTS: Twelve male subjects between the ages of 19 to 28 participated in this study. All subjects were healthy, had no missing teeth, and had no mechanical (orthodontic) appliances. MAIN OUTCOME MEASUREMENTS: For each condition, the system stiffness and damping values were estimated using the free vibration technique. Stiffness and damping values are relevant because they are the major determinants of impact force and, potentially, injury risk. It is the first study to show experimentally the quantitative effects of mouthguard in situ. RESULTS: All the mouthguards lowered the system stiffness as compared with the no mouthguard condition (P < 0.001). There was no observed effect on stiffness between the 2 limb orientation positions. Excitation weight had an unexpected effect on system stiffness (P = 0.041), with increasing weight leading to increased stiffness. CONCLUSIONS: The findings suggest that wearing any mouthguard is better than wearing none at all due to their ability to reduce system stiffness and damping values after a blow to the chin.     

Influence of intra-oral maxillary sports mouthguards on the airflow dynamics of oral breathing

PURPOSE: Mouthguards worn during sporting competition may influence oral airway flow dynamics and potentially increase airflow resistance during mouth breathing. METHODS: We measured oral airflow resistance (RO) in 10 normal subjects (four men, six women, age 29 +/- 3 yr, mean +/- SEM) wearing two different custom-made maxillary mouthguards. RESULTS: During tidal mouthpiece breathing (jaw position controlled), inspiratory R(O) (at (1.4 L x s(-1)) increased from 0.22 (0.15-0.46) cm H2O x L(-1) x s(-1) (median and interquartile range) to 0.47 (0.24-0.52) cm H2O x L(-1) x s(-1) with mouthguard 1 (general sports mouthguard) and from 0.34 (0.27-0.51) to 0.46 (0.39-0.86) cm H2O x L(-1) x s(-1) (N = 8) with mouthguard 2 (laminated, field hockey mouthguard, both P < 0.05). With oral only mask breathing (jaw position not controlled), inspiratory R(O) (at 0.4 L x s(-1)) increased to 1.02 (0.42-1.57) cm H2O x L(-1) x s(-1) (P < 0.03, compared with mouthpiece) but was variably affected by both mouthguards. At 1.0 L x s(-1), there was a tendency for both mouthguards to increase inspiratory R(O); however, this effect only reached significance for mouthguard 1 during mouthpiece breathing. CONCLUSION: Thus, although maxillary mouthguards do increase R(O) when jaw position is controlled, individual subjects respond differently when in control of mouth opening. This may be related to variable recruitment of compensatory mechanisms (e.g. mouth opening and/or oral airway dilator muscle activity).     

Physiological effects of wearing mouthguards.

Mouthguards are considered by most authorities to be an essential part of equipment for players participating in body-contact sports. Mouthguards provide excellent dental protection but not all players use them, complaining of breathing difficulties and problems with speaking. Although information exists concerning dental trauma and mouth protector use, there are no reported data that quantify the physiological effects of wearing mouthguards. The purpose of this study was to measure the ventilatory and gas exchange effects of wearing a mouthguard. Ten healthy men and seven women aged 20-36 years (mean(s.d.) 27.2(5.2) years) were used as subjects. Forced expiratory air volume at 1 s (FEV1) and peak expiratory flow rates (PEF) were measured on each subject while wearing either no mouthguard or one of three different over-the-counter mouthguards including one maxillary (mouthguard 1) and two different bimaxillary guards (mouthguards 2 and 3). To determine the effects of wearing each of the mouthguards during exercise, oxygen consumption (VO2) was measured while exercising on a cycle ergometer for 5 min at a light and heavy workload. An ANOVA of repeated measures was used to determine statistical differences. In each case, the wearing of a mouthguard significantly (P less than 0.05) reduced FEV1 and PEF in comparison with no mouthguard. FEV1 was reduced 8% with mouthguard 1, and 12% and 14% with mouthguards 2 and 3 respectively. PEF was reduced by 7, 15 and 15.8% with mouthguards 1, 2 and 3 respectively. The wearing of the different mouthguards did not significantly change VO2 while exercising at the lower work level whereas VO2 was significantly ( P < 0.05) reduced at the heavier workload. This surprising reduction in VO2 during heavy exercise may be due to a 'pursed-lip' type of breathing which has been shown to decrease CO2 tension, increase oxygenation and exercise tolerance. It can be concluded that although mouthguards may be perceptably uncomfortable and restrict forced expiratory air flow, they appear to be beneficial in prolonging exercise by improving ventilation and economy.     

Protective equipment use among female rugby players.

OBJECTIVES: Our objective was to assess the prevalence of protective equipment use and the motivation for using protective equipment among a sample of US female rugby players. DESIGN/METHODS: We surveyed a convenience sample of 234 current US female rugby players from 14 teams participating in a US women's rugby tournament, obtaining self-reported demographic, rugby exposure, and protective equipment use information. RESULTS: Mouthguards were the most commonly used piece of protective equipment: 90.8% of players reported having always worn a mouthguard while playing or practicing rugby within their most recent 3 months of play. Fewer than 15% of players reported having always worn other types of protective equipment. Equipment use varied by playing position. Whereas over 80% of players in all other positions always wore a mouthguard, 66.7% of scrum halves reported always wearing one. Both backs and forwards reported wearing shoulder pads, but only forwards reported always wearing padded headgear. Mouthguards, padded headgear, and shoulder pads were worn "to prevent injury," whereas ankle braces, neoprene sleeves, and athletic tape on joints were worn "to protect a current/recent injury." CONCLUSIONS: This is the first study of female rugby players to assess the prevalence of protective equipment use by playing position and the motivation for using protective equipment. With the exception of mouthguards, US female rugby players infrequently use protective equipment. Protective equipment use varies by playing position. Some types of protective equipment appear to be used as primary prevention mechanisms, whereas others are used as secondary or tertiary prevention mechanisms.     

Shock absorption capacities of mouthguards in different types and thicknesses

Although sports mouthguards provide protection against trauma, dentoalveolar injuries can still occur with the mouthguards in place. This study examined the effect of mouthguard protection in an in vitro model. A simulated maxilla, out of a polymethylmethacrylate (PMMA) arch, containing replaceable resin teeth, was used to assess the performance of different mouthguard designs. "Boil and bite" and custom-fitted mouthguards (ethylene vinyl acetate [EVA]) laminated with hard (poly-vinyl chloride [PVC]) or soft labial intermediate EVA layers were fabricated according to manufacturers' instructions. A steel ram was dropped onto the mouthguards at the maxillary incisor region. Changes in voltage, which were induced by a strain gauge at the back of the upper left incisor, were measured with an amplified voltmeter. Data were analysed by ANOVA at a significance level of 0.05. "Boil and bite" and mouthguards layered with silicone or with small hard PVC inserts of 1.5 mm thickness demonstrated less absorption and differed significantly from the other mouthguard systems (p < 0.05). Bilaminated mouthguards with hard PVC inserts of 0.8 mm, 1.5 mm or 2 mm thickness showed no significant differences to those with 1.5 mm thick (EVA) inserts. The absorption rates amounted to 33 % compared with the unprotected tooth.     

A comparison of athletic mouthguard materials

The development of protective mouthguards resulted from extensive injuries during participation in contact sports. This has produced a dramatic decrease in the incidence of injuries to the orofacial complex. Numerous materials and techniques have been used for mouthguard fabrication. The purpose of this investigation was to make an in vivo comparison of various thermoplastic mouthguard materials. Mouthguards were fabricated upon maxillary models of 40 members of the UCLA football team. The mouthguards were made of the following materials: poly (vinyl acetate-ethylene) copolymer clear thermoplastic; polyurethane; and laminated thermoplastic. Eleven measurements were taken for each mouthguard to demonstrate dimensional changes that occurred with wear. Statistical analyses determined differences between the types of mouthguards. The clear thermoplastic revealed less dimensional change than the polyurethane material. The laminated thermoplastic showed significantly less dimensional change than the other materials tested.     

Does silica–nylon mesh improves the biomechanical response of custom-made mouthguards?

Purpose

Mouthguards are used for injury prevention due to the high risk of dental and craniofacial injuries during sports activities. Therefore, the aim of this study was to evaluate the effect of silica–nylon mesh on the biomechanical performance of custom-made mouthguards using the finite element method.

Methods

Two custom-made mouthguards were modeled according to the presence or not of silica–nylon mesh. A 500 N load was applied in the region of the upper central incisors for both models. A mesh convergence test of 10% was conducted in the computer-aided analysis software to reduce the error during the results processing. An ideal contact interface was used between all contacts, simulating a situation in which the athlete would not lose his mouthguard upon impact. Also, the contact between the reinforcement and the mouthguard was defined as frictionless after a microscopic investigation. Maximum principal stress parameter was analyzed for bone, mouthguard, teeth, and skull displacement. Stress peaks for mouthguards and teeth were analyzed using one-way ANOVA.

Results

The results showed that the mesh presence neither influenced the skull displacement or the stress distribution in the bone, teeth or mouthguard. ANOVA showed no difference between the mesh presence or not, with 8.75?±?2.00 MPa mean value for the mouthguard and 9.88?±?2.75 MPa for the teeth.

Conclusions

The presence of a silica–nylon mesh did not modify the biomechanical response in the bone, teeth or mouthguard. In addition, even with the mouthguards in position, some damage can occur after the trauma.

     

DOMS-associated changes in ankle and knee joint dynamics during running

PURPOSE: The purpose of this study was to determine whether leg mechanics change due to DOMS by examining ankle and knee joint kinematics and stiffness before and after a down hill run. METHODS: Sagittal plane kinematics were recorded with high-speed (120 Hz) video at a speed representing 75% of VO2peak of nine well-trained male runners before (RE1) and 48 h after (RE2) a 30-min downhill run. From the recorded video, 10-12 consecutive strides were digitized, and the following variables were calculated for each stride: ankle and knee range of motion (ROM), ankle and knee peak angular velocity, ankle and knee stiffness, and leg vertical stiffness. A repeated measures ANOVA was calculated for each variable (alpha = 0.05). RESULTS: Both knee and ankle ROM during stance decreased with DOMS, but otherwise there were few changes in ankle mechanics with DOMS. Knee stiffness tended to increase during the early portion of stance (from initial stance to maximum angular velocity of flexion) with DOMS, immediately followed by a decrease (to maximum knee flexion) in stiffness. Changes in knee stiffness caused vertical leg stiffness to increase for the initial portion of stance with DOMS. CONCLUSION: Knee mechanics changed such that the knee stiffness increased at initial stance, resulting in an increase in vertical leg stiffness. This change in knee stiffness possibly serves as a protective mechanism to prevent further damage or pain in the knee extensor musculature.     

Exercise capacity in athletes with mouthguards

The objective of this study was to determine the effect of wearing a mouthguard on maximal exercise capacity and cardiopulmonary parameters at peak workload, and to assess the athletes' attitudes toward wearing a mouthguard. Thirteen volunteer male athletes (18 to 27 years old) were interviewed before and after delivery of a custom-made laminated mouthguard. A visual analogue scale (VAS, 0 - 100 mm) was used for judgment of interference with breathing, speaking, concentration and athletic performance. In addition, the athletes were subjected to a cardiorespiratory examination on a cycle ergometer with and without mouthguards. Subjectively, the athletes rated the mean interference with performance to be 37 mm VAS at the beginning of the study. Mean scores of impairment decreased to 23 mm VAS (p = 0.081) after wearing the mouthguard for four weeks, and further improved to 12 mm VAS (p < 0.001) after the test on the cycle ergometer. Objectively, the maximum workload during spiroergometry was even slightly elevated during exercise with the mouthguard (330.2 W) compared to exercise without the mouthguard (314.5 W). Peak minute ventilation and oxygen uptake were not different during exercise with and without the mouthguard. The present study demonstrated that a custom-made mouthguard does not significantly affect or reduce maximum exercise performance of athletes.     

Towards the development of a standard test procedure for mouthguard assessment

A simulated upper jaw, made from a rubber arch containing replaceable ceramic teeth and a renewable composite jawbone, offers promise in assessing the performance of custom made mouthguard designs. Impact tests, involving precise assessment of jaw and tooth fractures caused by projectiles of various energies and profiles, simulate conditions that approximate to common clinical observation. Such conditions offer the most sensitive indices for assessing both improved mouthguard designs and product quality and reliability. Damage caused by the dissipation of the impact energy may be transferred within this simulated oral cavity by minor changes to the impact conditions.     

Prevention of dental trauma in a high-risk military population: the discrepancy between knowledge and willingness to comply

Military fighters are at high risk for oral/tooth injuries. Our aim was to evaluate the knowledge and willingness to use preventive measures among this population to reduce oral trauma. A total of 336 fighters were randomly assigned to two groups. The control group answered a structured questionnaire, which included questions regarding: knowledge of the benefits of mouthguard use, past/current use, and willingness to use a mouthguard. The intervention group received a 60-minute dental trauma lecture, and responded to the same questionnaire. Significantly more subjects in the intervention group were familiar with the benefits of mouthguards compared to the control group, but there was no difference between the groups in their willingness to use mouthguards routinely. Discomfort and potential interference to sport performance were the most common reasons for rejection. It seems that a structured lecture is not sufficient for ensuring usage of mouthguards in a military population. Emphasis on motivation or mandating use may be required.     

Beneficial effects of air inclusions on the performance of ethylene vinyl acetate (EVA) mouthguard material

OBJECTIVE: To investigate the impact characteristics of an ethylene vinyl acetate (EVA) mouthguard material with regulated air inclusions, which included various air cell volumes and wall thickness between air cells. In particular, the aim was to identify the magnitude and direction of forces within the impacts. METHOD: EVA mouthguard material, 4 mm thick and with and without air inclusions, was impacted with a constant force impact pendulum with an energy of 4.4 J and a velocity of 3 m/s. Transmitted forces through the EVA material were measured using an accelerometer, which also allowed the determination of force direction and magnitude within the impacts. RESULTS: Statistically significant reductions in the transmitted forces were observed with all the air inclusion materials when compared with EVA without air inclusions. Maximum transmitted force through one air inclusion material was reduced by 32%. Force rebound was eliminated in one material, and reduced second force impulses were observed in all the air inclusion materials. CONCLUSION: The regulated air inclusions improved the impact characteristics of the EVA mouthguard material, the material most commonly used in mouthguards world wide.     

Effect of noncustom bimolar mouthguards on peak ventilation in ice hockey players.

OBJECTIVE: To examine the effect of a noncustom bimolar mouthguard on ventilation in female varsity ice hockey players. DESIGN: Prospective crossover study. MAIN OUTCOME MEASURES: Expired ventilation (VE), oxygen uptake (VO2), and heart rate were measured in 12 university varsity female ice hockey players while these players were skating on a skating treadmill. Data were collected for each player with and without a mouthguard at both submaximal and maximal efforts to recreate the intensity of games. RESULTS: VE and VO2 were similar (P > 0.05) with and without a noncustom bimolar mouthguard at submaximal effort. The mean VE at maximal effort (VEmax) was significantly lower (P < 0.05) using the mouthguard (108.5 l/min) compared with without a mouthguard (114.1 l/min). VO2 at maximal effort (VO2max) was significantly lower (P < 0.05) using the mouthguard (48.8 mL.kg.min) compared with without a mouthguard (52.4 mL.kg.min). Heart rates were similar for players with and without a mouthguard at both submaximal and maximal efforts. CONCLUSIONS: Noncustom bimolar mouthguards may reduce ventilation and oxygen uptake at maximal efforts by female ice hockey players.     

Outdoor dynamic subject-specific evaluation of internal stresses in the residual limb: hydraulic energy-stored prosthetic foot compared to conventional energy-stored prosthetic feet

The prosthetic foot plays an important role in propelling, breaking, balancing and supporting body loads while the amputee ambulates on different grounds. It is therefore important to quantify the effect of the prosthetic foot mechanism on biomechanical parameters, in order to prevent pressure ulcers and deep tissue injury. Our aim was to monitor the internal stresses in the residuum of transtibial amputation (TTA) prosthetic-users ambulating on different terrains, which the amputees encounter during their daily activities, i.e. paved floor, grass, ascending and descending stairs and slope. We specifically aimed to compare between the internal stresses in the TTA residuum of amputees ambulating with a novel hydraulic prosthetic foot compared to conventional energy storage and return (ESR) prosthetic feet. Monitoring of internal stresses was accomplished using a portable subject-specific real-time internal stress monitor. We found significant decrease (p<0.01) in peak internal stresses and in the loading rate of the amputated limb, while walking with the hydraulic foot, compared to walking with ESR feet. The loading rate calculated while ambulating with the hydraulic foot was at least three times lower than the loading rate calculated while ambulating with the ESR foot. Although the average decrease in internal stresses was ≈ 2-fold larger when replacing single-toe ESR feet with the hydraulic foot than when replacing split-toed ESR feet with the hydraulic foot, the differences were statistically insignificant. Our findings suggest that using a hydraulic prosthetic foot may protect the distal tibial end of the TTA residuum from high stresses, therefore preventing pressure-related injury and pain.     

Comparison of soccer shin guards in preventing tibia fracture

The goal of this study was to evaluate the effectiveness of a number of shin guards in protecting against tibia fracture in soccer players. A secondary purpose was to determine the relationship between the material and structural differences in shin guard design and the protection provided. Twenty-three commercially available shin guards were tested on a model leg containing a synthetic tibia that had been calibrated against human cadaver specimens. Each guard was categorized into one of four material types: plastic (N = 9), fiberglass (N = 6), compressed air (N = 4), and Kevlar (N = 4). The maximum combined force at the ends of the tibia, the principal strain on the posterior side of the tibia, and the contact time of the impact were measured using a drop track impact simulation. Shin guards provided significant protection from tibia fracture at all drop heights. The average guard reduced force by 11% to 17% and strain by 45% to 51% compared with the unguarded leg. At the higher drop heights, material composition and structural characteristics of the shin guards showed significant differences in protective abilities. These findings indicate that all shin guards provide some measure of protection against tibia fracture, although the level of protection may vary significantly among the different guards.     

The effects of ankle guards and taping on joint motion before, during, and after a squash match

The effects of ankle guards and taping on joint motion before, during, and after exercise were studied. Twelve league squash players played two matches, each lasting 1 hour. Two different ankle guards, and two types of tape applied by the same method, served as supports. A specially designed goniometer with electronic digital display (accuracy 1 degree) was used to determine joint range of motion: plantar-flexion and dorsiflexion, neutral inversion and eversion, plantar-flexed inversion and eversion. The results were statistically analyzed to determine the significance of the restriction provided by the supports. This revealed that the two ankle guards provided no significant support. The two tapes, however, provided significant support before exercise and after 10 minutes but not after 1 hour of exercise. Nonelastic (zinc oxide) tape proved to be the most restrictive at all times measured, especially prior to exercise, when the ankle's range of motion was decreased between 30% and 50%. However, once exercise commenced, the tape stretched, and restriction became less effective.