Single-Leg Drop Jump Biomechanics After Ankle or Knee Joint Cooling in Healthy Young Adults.

CONTEXT: It is unclear if lower-extremity joint cooling alters biomechanics during a functional movement. OBJECTIVE: To investigate the effects of unilateral lower-extremity cryotherapy on movement alterations during a single-leg drop jump. DESIGN: A crossover design. SETTING: Laboratory. PATIENTS: Twenty healthy subjects (10 males and 10 females; 23 y, 169 cm, 66 kg). INTERVENTION(S): Subjects completed a single-leg drop jump before and after a 20-minute ankle or knee joint cooling on the right leg, or control (seated without cooling) on 3 separate days. MAIN OUTCOME MEASURES: Time to peak knee flexion, vertical ground reaction force, lower-extremity joint angular velocity (sagittal plane only), and angle and moment (sagittal and frontal planes) in the involved leg over the entire ground contact (GC; from initial contact to jump-off) during the first landing. Time to peak knee flexion was compared using an analysis of variance; the rest of the outcome measures were analyzed using functional analyses of variance (P < .05). RESULTS: Neither joint cooling condition changed the time to peak knee flexion (F2,95 = 0.73, P = .49). Ankle joint cooling reduced vertical ground reaction force (55 N at 4% of GC), knee joint angular velocity (44°/s during 5%-9% of GC), and knee varus moment (181 N·m during 18%-20% of GC). Knee joint cooling resulted in a reduction in knee joint angular velocity (24°/s during 37%-40% of GC) and hip adduction moment (151 N·m during 46%-48% of GC), and an increase in hip joint angular velocity (16°/s during 49%-53% of GC) and plantarflexion angle (1.5° during 11%-29% of GC). CONCLUSION: Resuming activity immediately after lower-extremity joint cooling does not seem to predispose an individual to injury during landing because altered mechanics are neither overlapping with the injury time period nor of sufficient magnitude to lead to an injury.

Return to sport decisions after an acute lateral ankle sprain injury: introducing the PAASS framework-an international multidisciplinary consensus.

BACKGROUND: Despite being the most commonly incurred sports injury with a high recurrence rate, there are no guidelines to inform return to sport (RTS) decisions following acute lateral ankle sprain injuries. We aimed to develop a list of assessment items to address this gap. METHODS: We used a three-round Delphi survey approach to develop consensus of opinion among 155 globally diverse health professionals working in elite field or court sports. This involved surveys that were structured in question format with both closed-response and open-response options. We asked panellists to indicate their agreement about whether or not assessment items should support the RTS decision after an acute lateral ankle sprain injury. The second and third round surveys included quantitative and qualitative feedback from the previous round. We defined a priori consensus being reached at >70% agree or disagree responses. RESULTS: Sixteen assessment items reached consensus to be included in the RTS decision after an acute lateral ankle sprain injury. They were mapped to five domains with 98% panellist agreement-PAASS: Pain (during sport participation and over the last 24 hours), Ankle impairments (range of motion; muscle strength, endurance and power), Athlete perception (perceived ankle confidence/reassurance and stability; psychological readiness), Sensorimotor control (proprioception; dynamic postural control/balance), Sport/functional performance (hopping, jumping and agility; sport-specific drills; ability to complete a full training session). CONCLUSION: Expert opinion indicated that pain severity, ankle impairments, sensorimotor control, athlete perception/readiness and sport/functional performance should be assessed to inform the RTS decision following an acute lateral ankle sprain injury. TRIAL REGISTRATION NUMBER: ACTRN12619000522112.

Measurement of Ankle Joint Movements Using IMUs during Running.

Gait analysis has historically been implemented in laboratory settings only with expensive instruments; yet, recently, efforts to develop and integrate wearable sensors into clinical applications have been made. A limited number of previous studies have been conducted to validate inertial measurement units (IMUs) for measuring ankle joint kinematics, especially with small movement ranges. Therefore, the purpose of this study was to validate the ability of available IMUs to accurately measure the ankle joint angles by comparing the ankle joint angles measured using a wearable device with those obtained using a motion capture system during running. Ten healthy subjects participated in the study. The intraclass correlation coefficient (ICC) and standard error of measurement were calculated for reliability, whereas the Pearson coefficient correlation was performed for validity. The results showed that the day-to-day reliability was excellent (0.974 and 0.900 for sagittal and frontal plane, respectively), and the validity was good in both sagittal (r = 0.821, p < 0.001) and frontal (r = 0.835, p < 0.001) planes for ankle joints. In conclusion, we suggest that the developed device could be used as an alternative tool for the 3D motion capture system for assessing ankle joint kinematics.

Ankle Instability Patients Exhibit Altered Muscle Activation of Lower Extremity and Ground Reaction Force during Landing: A Systematic Review and Meta-Analysis.

This review aimed to investigate characteristics of muscle activation and ground reaction force (GRF) patterns in patients with ankle instability (AI). Relevant studies were sourced from PubMed, CINAHL, SPORTDiscus, and Web of Science through December 2019 for case-control study in any laboratory setting. Inclusion criteria for study selection were (1) subjects with chronic, functional, or mechanical instability or recurrent ankle sprains; (2) primary outcomes consisted of muscle activation of the lower extremity and GRF during landing; and (3) peer-reviewed articles with full text available, including mean, standard deviation, and sample size, to enable data reanalysis. We evaluated four variables related to landing task: (1) muscle activation of the lower extremity before landing, (2) muscle activation of the lower extremity during landing, (3) magnitude of GRF, and (4) time to peak GRF. The effect size using standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for these variables to make comparisons across studies. Patients with AI had a lower activation of peroneal muscles before landing (SMD = -0.63, p < 0.001, CI = -0.95 to -0.31), greater peak vertical GRF (SMD = 0.21, p = 0.03, CI = 0.01 to 0.40), and shorter time to peak vertical GRF (SMD = -0.51, p < 0.001, CI = -0.72 to -0.29) than those of normal subjects during landing. There was no significant difference in other muscle activation and GRF components between the patients with AI and normal subjects (p > 0.05). Altered muscle activation and GRF before and during landing in AI cases may contribute to both recurrent ankle and ACL injuries and degenerative change of articular.

Effects of a 4-Week Short-Foot Exercise Program on Gait Characteristics in Patients With Stage II Posterior Tibial Tendon Dysfunction.

CONTEXT: Clinically, it has been suggested that increased activation of intrinsic foot muscles may alter the demand of extrinsic muscle activity surrounding the ankle joint in patients with stage II posterior tibial tendon dysfunction. However, there is limited empirical evidence supporting this notion. OBJECTIVE: The purpose of this study was to investigate the effects of a 4-week short-foot exercise (SFE) on biomechanical factors in patients with stage II posterior tibial tendon dysfunction. DESIGN: Single-group pretest-posttest. SETTING: University laboratory. PARTICIPANTS: Fifteen subjects (8 males and 7 females) with stage II posterior tibial tendon dysfunction who had pain in posterior tibial tendon, pronated foot deformity (foot posture index ≥+6), and flexible foot deformity (navicular drop ≥10 mm) were voluntarily recruited. INTERVENTION: All subjects completed a 4-week SFE program (15 repetitions × 5 sets/d and 3 d/wk) of 4 stages (standing with feedback, sitting, double-leg, and one-leg standing position). MAIN OUTCOME MEASURES: Ankle joint kinematics and kinetics and tibialis anterior and fibularis longus muscle activation (% maximum voluntary isometric contraction) during gait were measured before and after SFE program. Cohen d effect size (ES [95% confidence intervals]) was calculated. RESULTS: During the first rocker, tibialis anterior activation decreased at peak plantarflexion (ES = 0.75 [0.01 to 1.49]) and inversion (ES = 0.77 [0.03 to 1.51]) angle. During the second rocker, peak dorsiflexion angle (ES = 0.77 [0.03 to 1.51]) and tibialis anterior activation at peak eversion (ES = 1.57 [0.76 to 2.39]) reduced. During the third rocker, the peak abduction angle (ES = 0.80 [0.06 to 1.54]) and tibialis anterior and fibularis longus activation at peak plantarflexion (ES = 1.34 [0.54 to 2.13]; ES = 1.99 [1.11 to 2.86]) and abduction (ES = 1.29 [0.50 to 2.08]; ES = 1.67 [0.84 to 2.50]) decreased. CONCLUSIONS: Our 4-week SFE program may have positive effects on changing muscle activation patterns for tibialis anterior and fibularis longus muscles, although it could not influence their structural deformity and ankle joint moment. It could produce a potential benefit of decreased tibialis posterior activation.

Sports injury and illness incidence in the PyeongChang 2018 Olympic Winter Games: a prospective study of 2914 athletes from 92 countries.

OBJECTIVE: To describe the incidence of injuries and illnesses sustained during the XXIII Olympic Winter Games, hosted by PyeongChang on 9-25 February 2018. METHODS: We recorded the daily number of athlete injuries and illnesses (1) through the reporting of all National Olympic Committee (NOC) medical teams and (2) in the polyclinic and medical venues by the PyeongChang 2018 medical staff. RESULTS: In total, 2914 athletes (1210 women, 42%; 1704 men, 58%) from 92 NOCs were observed for occurrence of injury and illness. NOC and PyeongChang 2018 medical staff reported 376 injuries and 279 illnesses, equalling 12.6 injuries and 9.4 illnesses per 100 athletes over the 17-day period. Altogether, 12% of the athletes incurred at least one injury and 9% at least one illness. The injury incidence was highest in ski halfpipe (28%), snowboard cross (26%), ski cross (25%), snowboard slopestyle (21%) and aerials (20%), and lowest in Nordic combined, biathlon, snowboard slalom, moguls and cross-country skiing (2%-6%). Of the 376 injuries recorded, 33% and 13% were estimated to lead to ≥1 day and >7 days of absence from sport, respectively. The highest incidences of illness were recorded in biathlon (15%), curling (14%), bobsleigh (14%) and snowboard slalom (13%). Thirty per cent of the illnesses were expected to result in time loss, and 70% affected the respiratory system. Women suffered 61% more illnesses than men. CONCLUSION: Overall, 12% of the athletes incurred at least one injury during the Games and 9% an illness, incidences that are similar to the Olympic Winter Games of 2010 and 2014.

Safety Evaluation of Protective Equipment for the Forearm, Shin, Hand and Foot in Taekwondo.

The objective of the study was to evaluate and compare different brands of forearm, shin, hand and foot protective equipment used in Taekwondo. The most popular brands of large forearm, shin, hand and foot protectors (D®, A®, K ®), approved by the World Taekwondo and Korean Taekwondo Association, were examined. A drop test was used to test the protective equipment using impact levels of 3J, 9J, 12J and 15J for the forearm and shin guards, and 3J and 9J for the hand and foot protectors. The protective equipment was hit ten times from each of the designated drop heights. The drop test is described in the European standards manual of protective equipment for martial arts (SRPS EN 13277-2). The maximum force (MF) and impulse were lowest for brand K® (2610.3 ± 1474.1 N), and brand A® (9.6 ± 3.1 Ns), respectively, for the forearm guards; for brand A® (2053.4 ± 1267.1 N) and brand K® (9.8 ± 3.5 Ns), respectively, for the shin guards; for brand K® (4486.5 ± 1718.4 N), and brand A® (6.3 ± 1.1 Ns), respectively for the hand protectors; and for brand A® (3733.7 ± 2465.3 N), and brand D® (6.8 ± 0.6 Ns), respectively, for the foot protectors. For the forearm guard brand and impact level, there was a significant interaction effect for the MF (F=42.44, η2=.677, p <0.001) and impulse (F = 33.97, η2 = 0.626, p <0.001). Based on the MF, brand K® performed the best for the forearm guards and hand protectors, and brand A®, for the shin guards and foot protectors. The best results for the impulse were for brand A® (forearm guards and hand protectors), brand K® (shin guards) and brand D® (foot protectors).

Rotational and linear head accelerations from taekwondo kicks and punches.

The purpose was to compare rotational and linear head accelerations as a result of taekwondo kicks and punches. Taekwondo athletes executed five repetitions of the turning kick, spinning hook kick, hook punch, straight punch, and jab punch to a Hybrid III Crash Test Dummy head-neck complex. A tri-axial accelerometer and an angular rate sensor were mounted inside the Hybrid III head to measure resultant linear (RLA) and rotational accelerations. The Hybrid III was fixed to a height-adjustable frame and fitted with protective taekwondo headgear. Dummy head height was positioned to each participant's standing height. Acceleration data were processed in accordance with SAE J211-1.There was no significant multivariate difference in RLA but the effect was not clear. Univariate follow-up analysis showed a significant difference in RLA but the effect was also not clear. There was no difference in rotational acceleration. The highest RLA and rotational acceleration were produced, in order, by the turning kick, hook kick, hook punch, straight punch, and jab. These data are clinically important as they provide a better understanding of the biomechanical injury measures and support for improved headgear testing methodology.

Injuries among Korean Female Professional Golfers: A Prospective Study.

This study aims to analyze the incidence, location, type, and mechanisms of injuries and possible injury risk factors among all levels of Korean female professional golfers. This was a prospective study with a follow-up period of 24 months. A total of 363 members of the Korean Ladies Professional Golf Association (KLPGA), who competed in tournaments during the 2015 and 2016 seasons, took part in the study. The incidence of injury varied by tournament level and was significantly higher in Division II (11.1/1000AEs) and Division III (13.4/1000AEs) than in Division I (5.6/1000AEs) (p < 0.05). The most common location and type of injury were the shoulder/clavicle (Division I: 14.1%, Division II: 15.7%, Division III: 17.3%) and the tendinosis or tendinopathy (21.2%) (Division I: 23.7%, Division II: 21.2%, Division III: 18.5%), respectively. The most common mechanism of injury was the golf swing (47.9%-51.6% for the three divisions), and the most frequent specific phase of injury was upon ball impact (23.5%-30.9%). Multivariate analysis revealed that body mass index and the number of previous season competitions were significantly associated with injury risk in female golfers. The other factors examined did not have a significant association with golf-related injuries. In conclusion, KLPGA golfers were commonly exposed to injuries and showed a higher rate of injuries in competitions than practices, with significantly higher in Division II, III than Division I. However, overall, there was no significant difference in the location, type, mechanism and risk factors for injuries among the division level of KLPGA.

Biomechanical Effects of Ball Position on Address Position Variables of Elite Golfers.

The purpose of this study was to investigate address position variables in response to changes in ball position in golfers. Eleven male professional golfers were instructed to perform their golf swing. A three-dimensional motion analysis system, with eight infrared cameras and two force platforms, was used to capture the address positions. A golf ball has a diameter of 4.27 cm, and a radius of 2.14 cm. Even small movements of ball position in the mediolateral (M-L) and anteroposterior (A-P) directions significantly changed the address position. When the ball was moved to the left, the shoulder rotation and club-face aim rotated toward the left of the target, and the left vertical ground reaction force increased. When the ball was moved to the right, the opposite findings were observed. When the ball was moved closer, the trunk, hip, knee, ankle, and absolute arm angle extended; the lie angle of the golf club increased; and the center of pressure moved toward the posterior direction. These changes were reversed when the ball was moved further away. The M-L ball position critically changed the address positions of the upper extremities in the horizontal plane, and the A-P ball position critically changed the angles of whole body parts in the sagittal plane. Furthermore, club-head kinematics at impact such as club-face aim, club path, and angle of attack were significantly changed in the M-L ball position; and club-head speed and angle of attack were significantly changed in the A-P ball position. This in-depth understanding of the address position in association with the ball position could provide valuable data for swing coaches when finding a golfer's optimal address position.

Acute effects of whole body vibration on balance in persons with and without chronic ankle instability.

Chronic ankle instability (CAI) is a common condition following ankle injury that is associated with compromised balance. Whole body vibration training (WBVT) programmes are linked with improved balance and function in athletic and non-athletic populations and may improve balance in CAI. Twelve healthy and seven CAI participants completed two randomly assigned interventions. Two Power Plate® platforms were attached back to back using a Theraband®. Participants stood on the active plate and inactive plate for WBVT and sham interventions, respectively. Each intervention included vibration of the active plate. Centre of pressure (COP) and the star excursion balance test (SEBT) were measured before and at 3, 15 and 30 min following the interventions. Significant improvements were found in the anterior direction of the SEBT following both interventions in CAI and varying patterns of improvement were observed for COP measurements in all participants. Therefore, WBVT does not appear to acutely improve balance in CAI.

Changing sagittal plane body position during single-leg landings influences the risk of non-contact anterior cruciate ligament injury.

PURPOSE: To examine the effects of different sagittal plane body positions during single-leg landings on biomechanics and muscle activation parameters associated with risk for anterior cruciate ligament (ACL) injury. METHODS: Twenty participants performed single-leg drop landings onto a force plate using the following landing styles: self-selected, leaning forward (LFL) and upright (URL). Lower extremity and trunk 3D biomechanics and lower extremity muscle activities were recorded using motion analysis and surface electromyography, respectively. Differences in landing styles were examined using 2-way Repeated-measures ANOVAs (sex × landing conditions) followed by Bonferroni pairwise comparisons. RESULTS: Participants demonstrated greater peak vertical ground reaction force, greater peak knee extensor moment, lesser plantar flexion, lesser or no hip extensor moments, and lesser medial and lateral gastrocnemius and lateral quadriceps muscle activations during URL than during LFL. These modifications of lower extremity biomechanics across landing conditions were similar between men and women. CONCLUSIONS: Leaning forward while landing appears to protect the ACL by increasing the shock absorption capacity and knee flexion angles and decreasing anterior shear force due to the knee joint compression force and quadriceps muscle activation. Conversely, landing upright appears to be ACL harmful by increasing the post-impact force of landing and quadriceps muscle activity while decreasing knee flexion angles, all of which lead to a greater tibial anterior shear force and ACL loading. ACL injury prevention programmes should include exercise regimens to improve sagittal plane body position control during landing motions.

Incidence of Sport Injuries in the Manchester 2019 World Taekwondo Championships: A Prospective Study of 936 Athletes from 145 Countries.

We aimed to describe injury incidence and patterns at the 2019 World Taekwondo Championships (WTC), and to compare them with those of previous WTCs, based on new World Taekwondo (WT) competition rules, medical codes, and the Protector and Scoring System (PSS). This prospective cohort study utilized data obtained through the WT Injury Surveillance System. All athletes with injuries were evaluated by on-site sports medicine specialists, and ultrasonography was used to assess all musculoskeletal injuries. Of 936 athletes, 60 injuries were recorded (6.4 injuries/100 athletes, 95% confidence intervals [CI]: 4.8-8.0), and 4.5% (n = 42) sustained at least one injury. Males had a higher risk of sustaining injuries than females (incidence rate ratio: 1.57; 95% CI: 0.89-2.76). The most common sites, type, and mechanism were lower extremities (n = 26, 43.33%), contusion/hematoma/bruises (n = 33, 55.0%), and contact with another athlete (n = 50, 83.33%). Overall, the injury patterns associated with the mechanism of injury were similar in both the 2019 and 2017 WTCs. Refined WT competition rules and a re-established PSS at the 2019 WTC reduced the overall and severe injury incidence. Our findings can help revise Taekwondo competition rules, enhance protective equipment, optimize on-site venue medical systems, and develop injury prevention projects.

Pilot study comparing changes in postural control after training using a video game balance board program and 2 standard activity-based balance intervention programs.

OBJECTIVE: To compare the impacts of Tai Chi, a standard balance exercise program, and a video game balance board program on postural control and perceived falls risk. DESIGN: Randomized controlled trial. SETTING: Research laboratory. PARTICIPANTS: Independent seniors (N=40; 72.5±8.40) began the training, 27 completed. INTERVENTIONS: Tai Chi, a standard balance exercise program, and a video game balance board program. MAIN OUTCOME MEASURES: The following were used as measures: Timed Up & Go, One-Leg Stance, functional reach, Tinetti Performance Oriented Mobility Assessment, force plate center of pressure (COP) and time to boundary, dynamic posturography (DP), Falls Risk for Older People-Community Setting, and Falls Efficacy Scale. RESULTS: No significant differences were seen between groups for any outcome measures at baseline, nor were significant time or group × time differences for any field test or questionnaire. No group × time differences were seen for any COP measures; however, significant time differences were seen for total COP, 3 of 4 anterior/posterior displacement and both velocity, and 1 displacement and 1 velocity medial/lateral measure across time for the entire sample. For DP, significant improvements in the overall score (dynamic movement analysis score), and in 2 of the 3 linear and angular measures were seen for the sample. CONCLUSIONS: The video game balance board program, which can be performed at home, was as effective as Tai Chi and the standard balance exercise program in improving postural control and balance dictated by the force plate postural sway and DP measures. This finding may have implications for exercise adherence because the at-home nature of the intervention eliminates many obstacles to exercise training.

Effect of static foot alignment on plantar-pressure measures during running.

CONTEXT: Altered foot dynamics due to malalignment of the foot may change plantar-pressure properties, resulting in various kinds of overuse injuries. OBJECTIVE: To assess the effect of foot characteristics on plantar-pressure-related measures such as maximum pressure, maximum pressure-time, and pressure-time integral underneath the medial aspect of the foot during running. DESIGN: Cross-sectional. SETTING: Laboratory. PARTICIPANTS: 8 men and 17 women. MAIN OUTCOME MEASURES: Static non-weight-bearing rear-foot and forefoot alignment and navicular drop were measured. Plantar-pressure data were collected while subjects jogged at 2.6 m/s on a treadmill. Maximum pressure, time to maximum pressure, and pressure-time integral of the medial side of the foot were extracted for data analysis. Multiple-regression analysis was used to examine the effect of arch height and rear-foot and forefoot alignment on maximum pressure and pressure-time integral in the medial side of the foot. RESULTS: In the medial rear-foot and midfoot regions, only rear-foot alignment had a significant effect on the variance of maximum pressure and pressure-time integral. There were no significant difference effects in the medial forefoot region. CONCLUSION: Rear-foot alignment was found to be a significant predictor of maximum plantar pressure and pressure-time integral in the medial rear-foot and midfoot regions. This indicates that control of rear-foot alignment may help decrease plantar pressure on the medial region of the foot, which may potentially prevent injuries associated with excessive rear-foot eversion.

Epidemiological study of post-traumatic ankle osteoarthritis after ankle sprain in 195,393 individuals over middle age using the National Health Insurance Database: A retrospective design.

OBJECTIVES: This study aimed to determine the risk of ankle OA onset after an incidence of sprain, relative to the risk of onset in healthy population, and to investigate the effect of gender, age, BMI, and exercise on the development of ankle OA after sprain. DESIGN: Retrospective cohort study. METHODS: Using a sample cohort dataset from 2002 to 2013 provided by the Korean National Health Insurance Sharing Service, we calculated the mean survival time and cumulative incidence rate in sprained and healthy populations using Kaplan-Meier analysis. A Cox proportional hazards model was used to analyze the adjusted hazard ratio (HR) of sprain for the development of OA with 95% confidence intervals (CIs). Adjusted HRs of gender, age, BMI, and exercise (yes/no) were analyzed in the sprained group. RESULTS: Among the selected population of 195,393 individuals, 40,876 (20.9%) were diagnosed with an ankle sprain, and 1543 (3.85%) of those individuals developed ankle OA. Of the 154,517 healthy individuals (79.1%), 4062 (2.66%) cases had progressed to OA. The sprained group had 46% (HR, 1.46; 95% CI, 1.38-1.55) greater rate of progression to ankle OA than did healthy individuals. In the sprain group, individuals who were female, obese, and overweight had 40% (HR, 1.40; 95% CI, 1.26-1.55), 43% (HR, 1.43; 95% CI, 1.12-1.82), and 22% (HR, 1.22; 95% CI, 1.10-1.35) higher incidence to develop ankle OA, respectively, compared to those who were male, underweight and normal. CONCLUSIONS: This study found that ankle sprain was a significant risk factor for a diagnosis of early OA. Female gender and high BMI increased the incidence of ankle OA after sprain.

Mechanisms of Sports Concussion in Taekwondo: A Systematic Video Analysis of Seven Cases.

Sports-related traumatic brain injuries are the most common injury in adolescents and young adults due to recurrent concussion experiences and head shock. Therefore, this study was designed to describe player characteristics and situational factors associated with concussions in the World Taekwondo Championships using systematic video analysis. Athlete injury data were collected using a web-based injury surveillance system at the World Taekwondo Championships organized by World Taekwondo from 2017 to 2019. Seven video footage were independently analyzed by four analysts using a modified Heads-Up Checklist. Descriptive statistical analysis was used. The incidence of concussion was 3.21 per 1000 games. Most players with concussions were shorter than their opponents, and most concussions were caused by a roundhouse kick on the front of the face. Regarding the acceleration direction of the head after the impact, transverse and multiplane directions were the most common. Most players with a concussion have used a closed stance and did not use blocking techniques during the defense. The rate of concussions caused by penalties was 42.9%. Based on our findings, no other injury mechanisms, except for direct blows to the head, were observed. Therefore, education on the risk and symptoms of concussion, the appropriate management and blocking techniques should be emphasized in TKD-S to reduce incidence of concussion.

Altered Biomechanics in Individuals With Chronic Ankle Instability Compared With Copers and Controls During Gait.

CONTEXT: Given that motions of 1 segment affect those of an adjacent segment, the authors of biomechanical studies must thoroughly investigate the kinematics and kinetics of the proximal joints (hip and knee) as well as the ankle joints in patients with chronic ankle instability (CAI). However, few researchers have investigated the altered movement strategies of the lower extremities of patients with CAI compared with lateral ankle-sprain (LAS) copers and control participants throughout the full gait cycle of walking and jogging. OBJECTIVE: To evaluate lower extremity biomechanical differences in patients with CAI, LAS copers, and control individuals during gait. DESIGN: Case-control study. SETTING: Controlled laboratory setting. PATIENTS OR OTHER PARTICIPANTS: A total of 54 participants, consisting of 18 patients with CAI (age = 24.6 ± 2.8 years, height = 173.0 ± 8.0 cm, mass = 67.8 ± 14.6 kg), 18 LAS copers (age = 26.0 ± 4.6 years, height = 173.4 ± 7.5 cm, mass = 66.9 ± 10.3 kg), and 18 control individuals (age = 26.2 ± 2.3 years, height = 172.2 ± 8.2 cm, mass = 63.3 ± 11.2 kg). MAIN OUTCOME MEASURE(S): Three-dimensional kinematics and kinetics of the lower extremity during walking and jogging. RESULTS: The CAI group exhibited dorsiflexion deficits and more inverted ankles compared with the LAS coper and control groups during walking and jogging. In addition, the LAS coper group generated greater knee internal-rotation moments than did the CAI group during jogging. The other variables did not differ among groups. CONCLUSIONS: Participants with CAI demonstrated altered biomechanics, which need to be addressed via intervention programs.

Increased in-shoe lateral plantar pressures with chronic ankle instability.

BACKGROUND: Previous plantar pressure research found increased loads and slower loading response on the lateral aspect of the foot during gait with chronic ankle instability compared to healthy controls. The studies had subjects walking barefoot over a pressure mat and results have not been confirmed with an in-shoe plantar pressure system. Our purpose was to report in-shoe plantar pressure measures for chronic ankle instability subjects compared to healthy controls. METHODS: Forty-nine subjects volunteered (25 healthy controls, 24 chronic ankle instability) for this case-control study. Subjects jogged continuously on a treadmill at 2.68 m/s (6.0 mph) while three trials of ten consecutive steps were recorded. Peak pressure, time-to-peak pressure, pressure-time integral, maximum force, time-to-maximum force, and force-time integral were assessed in nine regions of the foot with the Pedar-x in-shoe plantar pressure system (Novel, Munich, Germany). RESULTS: Chronic ankle instability subjects demonstrated a slower loading response in the lateral rearfoot indicated by a longer time-to-peak pressure (16.5% +/- 10.1, p = 0.001) and time-to-maximum force (16.8% +/- 11.3, p = 0.001) compared to controls (6.5% +/- 3.7 and 6.6% +/- 5.5, respectively). In the lateral midfoot, ankle instability subjects demonstrated significantly greater maximum force (318.8 N +/- 174.5, p = 0.008) and peak pressure (211.4 kPa +/- 57.7, p = 0.008) compared to controls (191.6 N +/- 74.5 and 161.3 kPa +/- 54.7). Additionally, ankle instability subjects demonstrated significantly higher force-time integral (44.1 N/s +/- 27.3, p = 0.005) and pressure-time integral (35.0 kPa/s +/- 12.0, p = 0.005) compared to controls (23.3 N/s +/- 10.9 and 24.5 kPa/s +/- 9.5). In the lateral forefoot, ankle instability subjects demonstrated significantly greater maximum force (239.9N +/- 81.2, p = 0.004), force-time integral (37.0 N/s +/- 14.9, p = 0.003), and time-to-peak pressure (51.1% +/- 10.9, p = 0.007) compared to controls (170.6 N +/- 49.3, 24.3 N/s +/- 7.2 and 43.8% +/- 4.3). CONCLUSION: Using an in-shoe plantar pressure system, chronic ankle instability subjects had greater plantar pressures and forces in the lateral foot compared to controls during jogging. CLINICAL RELEVANCE: These findings may have implications in the etiology and treatment of chronic ankle instability.

Validity and Reliability of a Novel Instrument for the Measurement of Subtalar Joint Axis of Rotation.

Inclination of the subtalar joint (STJ) in the sagittal and transverse planes may be highly associated with ankle pathology. However, the validity and reliability of measuring the inclination of the STJ axis of rotation (AoR) is not well established. This study aimed to develop a custom-made STJ locator (STJL) and evaluate its reliability and validity. To establish the reliability and validity of the measurement device for STJ AoR, 38 healthy male participants were recruited. For the reliability analysis, test-retest was used, and for validity analysis, Pearson's correlation and Bland-Altman plot analyses were performed. In the reliability analysis of the STJL, a higher correlation was observed with the sagittal plane (0.930) and transverse plane (0.748) (standard error of measurement: 0.56-0.78; minimal detectable difference: 1.57-2.16). In the validity analysis between radiography and STJL, a significantly higher value of 0.798 was obtained with radiography (42.5) and STJL (43.5) with the sagittal plane. The custom-made STJL may be used in the clinical setting as its validity and intraclass correlation coefficient were high, indicating consistent measurements. Further studies including motion analysis are necessary to provide more information regarding the relationship between STJ AoR inclinations and STJ movements.