Non-contact Situations Research Articles

Supporter-Type Anterior Cruciate Ligament Prevention System Based on Estimation of Knee Joint Valgus Angle Using Stretch Sensors

Anterior cruciate ligament (ACL) injuries are common in sports involving jumping and rapid direction changes, often occurring in non-contact situations. The risk of ACL injury is evaluated by knee flexion and valgus angles; a small knee flexion angle combined with a large valgus angle increases the risk. Monitoring these angles during activities can help athletes recognize their ACL injury risk and adjust their movements. Traditional 3D motion analysis, used for measuring knee angles, is costly and impractical for daily practice. This study proposes a knee supporter with stretch sensors to estimate knee flexion and valgus angles in practice settings, evaluating ACL injury risk and notifying athletes of high-risk movements. The proposed device wirelessly transmits data from three stretch sensors placed on the device to a PC and uses machine learning to estimate the knee angles. The results of the evaluation experiments, conducted with data from five healthy male and female participants in their twenties, indicate that the estimation accuracy for the knee flexion angle, achieved by a model trained using a Random Forest Regressor (RFR) with data from individuals other than the target user, resulted in a Mean Absolute Error (MAE) of 8.86 degrees. For the knee valgus angle, a model trained with the user’s own data using the RFR achieved a MAE of 0.81 degrees.

Lower Quarter Y-Balance Test Anterior Reach Asymmetry and Noncontact Lower Limb Injury in Subelite Young Male Soccer Players With Different Training Experiences

Poor single-leg balance performance is associated with an increased risk of sustaining lower limb injuries in team sports. However, it is unclear whether this relationship is modified by the level of training experience (years of training experience). The objective of the present study was to evaluate whether soccer players’ single-leg balance performance is related to lower limb injuries in noncontact situations with different levels of training experience. Subelite young male soccer players performed the Lower Quarter Y-Balance Test with the dominant and the nondominant leg at the beginning of the preseason. Due to COVID-19 rules, the occurrence of lower limb injuries during the second half of the competitive season was documented. The odds of injury were calculated based on a previously reported Lower Quarter Y-Balance Test cut-off score for side-to-side anterior reach difference (≥4 cm). Twelve soccer players sustained a lower leg injury in noncontact situations. Only four of them had an anterior reach difference equal to or above the cut-off score. Soccer training experience has no significant influence on the association between Lower Quarter Y-Balance Test anterior reach asymmetry and noncontact lower limb injury in young male players.

Changes in Daily Life, Physical Activity, GAD, Depression, and Personal Hygiene of Adolescents in South Korea Due to the COVID-19.

This study used raw data obtained from the Adolescents’ Health Behavior Survey by government-affiliated agency open data. A total of 109,796 students were sampled. A comparative analysis was performed based on the year 2020 and when the COVID-19 pandemic occurred, in which we analyzed changes in adolescents’ depression and panic anxiety perception and dietary habits, physical factors, physical activity, and handwashing habits. There was no weight control in the second year compared to the first year of the COVID-19 pandemic, and obesity also increased. The continuation of the non-contact situation caused by COVID-19 led to a worsening of subjective health awareness, and the experience of generalized anxiety disorder, depression, sadness and hopelessness, and suicidal thoughts and attempts increased. The frequency of washing hands with soap before meals and after using the toilet at school or at home was reduced. As a result of this analysis, we believe that there needs to be a system of support in place to address the academic gaps and deficiencies in learning caused by COVID-19, and that psychological and emotional support needs to be strengthened at this time, as well as the issues to be supported after the end of the non-contact situation.

코로나19 팬데믹 상황에서의 유아기 자녀를 둔 어머니 양육경험에 대한 사례연구

This is a case study on the parenting experience of mothers who raised infants during the COVID-19 pandemic. The study was conducted from August 2021 to October 2021 through in-depth interviews with four mothers with children between the age of 3 and 6, and data analysis was conducted using the case analysis method suggested by Creswell(2013). The similarities between the cases were as follows: First, the participants chose home childcare, but as they faced limitations; they decided to send their children to attend school again. Second, participants were able to adapt to the COVID-19 pandemic through the assistance of people around them. Third, participants said that COVID-19 reduced their travel and experience opportunities. Fourth, the participants gradually became apathetic and adapted to the changed circumstances. The differences between the cases were as follows: First, among the working mothers, those who experienced career breaks perceived the meaning of work more positively. Second, participants with poor social support resources experienced greater difficulty in nurturing their children. Third, participants raising children with developmental disabilities were more concerned about the child’s development than the COVID-19 infection and accordingly had to play multiple roles. Based on the results of this study, the meaning of the mother’s parenting experience in the COVID-19 pandemic assessed by the researcher was as follows: First, the heavy responsibility and burden of mothers stood out, and mothers living in the COVID-19 situation were forced to play multiple roles, akin to a superwoman. Second, in the non-contact situation caused by COVID-19, the imbalance between the degree of social exchange and resources for emotional support was revealed more clearly.

The influence of soccer shoes on plantar distribution in young players in a static condition: a pilot study.

Injuries are a serious problem in soccer for the player but also for the society. It has been noted most of the injuries occurs during non-contact situations and, the soccer shoes have an important role. Unfortunately, few studies investigated the plantar distribution, argument that could help to deeply understand the causes behind the injuries. The objective was to evaluate the influence of the soccer shoes on plantar distribution in young players in a static condition. Young soccer players (range 11-18) were recruited and performed two tests on a baropodometric platform, one barefoot and one with technical soccer shoes. A student's t-test was performed to evaluate the differences between the conditions. Significative results were between the left plantar surface (P<0.05) and in the total surface anterior (P<0.05) with and without the soccer shoe. Related to the pressure values, soccer shoes resulted higher than barefoot condition. Statistical significance has been found also between the forefoot and the rearfoot in the left foot, in barefoot condition (P<0.05). Soccer shoes generally produce a reduction in the contact plantar surface, especially in the anterior zone and the foot load is higher in the forefoot zone.

팬데믹 현상을 통해 본 실버댄스 참여의 한계와 개선 방향에 관한 연구

This study finds the limits of participation in silver dance among the elderly who are in the worst environment in the pandemic situation caused by COVID-19. As a result, the elderly faced many difficulties, such as fear of life, lack of social activity, and difficulties in maintaining physical health. One of them was the experience of being completely cut off from silver dance activities, which had been one of his leisure activities. Therefore, through this study, the future direction of performing silver dance in non-contact situations such as a pandemic is explored to find ways for the elderly to maintain their health through performing silver dance despite social isolation.

A practical optimisation method of submarine base considering vibration reduction, light-weight and shock resistance

ABSTRACT Engine base plays an important role in a submarine. To enhance the vitality of the submarine, the base should resist shock under underwater non-contact explosion situations. To improve the submarine’s acoustic-stealth characteristics, the base also needs to have an excellent vibration isolation ability. This paper establishes a multi-level and multi-objective optimisation method for the submarine base structure. The strong coupling interaction between the submarine structure and seawater is considered. Taking structure shock safety, vibration isolation and base light-weight as multi-objectives, the artificial intelligence technology is applied to optimise the size and shape of the base structure. With the optimisation, the total vibration level difference in the base is improved by 3.06 dB and the mass of the base is reduced by 26.16%. The adopted optimisation method in this paper could give references for the engineering design of the submarine base.

Nine typical injury patterns in German professional male football (soccer): a systematic visual video analysis of 345 match injuries

AimWe aimed to systematically analyse the videos of acute injuries in professional men’s football and describe typical injury patterns.MethodsInjuries were registered with the German statutory accident insurance for professional athletes...

Patella dislocation: an online systematic video analysis of the mechanism of injury

BackgroundThe mechanism of injury (MoI) for a patellar dislocation has not been fully established. The aim of this study was to use systematic video analysis to determine the MoI of a patella dislocation.MethodsA systematic search was conducted of three video sharing websites and three popular search engines to identify videos demonstrating a patellar dislocation. Videos were reviewed by three surgeons trained in systematic video analysis, who commented on the position of the lower limb and the situation in which the injury occurred. The results were reviewed to build a consensus of the MoI for each video. Statistical analysis was conducted for interobserver agreement (p < 0.05).ResultsInitial search yielded 603 videos with 13 meeting the inclusion criteria. The injuries were sustained performing a sporting activity (n = 9) or whilst dancing (n = 4). The injury was predominantly sustained during a non-contact situation (n = 10). The most common mechanism was an unbalanced individual with a flexed hip sustaining a valgus force to their flexed knee with the tibia externally rotated.ConclusionsThis study provides some insight into the MoI for a patellar dislocation and the findings may assist in developing injury prevention programmes and rehabilitation protocols as well as guiding future research.

Epidemiology of physical activity-related injuries in Chinese university students.

Knowledge gaps of the physical activity-related injury (PARI) problem among general undergraduates exist. We conducted a study in four universities, where 1421 students graded 1-3 were interviewed face-to-face during April and May after their completion of the baseline survey in March and April 2017, aiming to describe the incidence and characteristics of PARI. PARI experience and physical activity (PA) participation in the past 12months were collected. Injury incidence density (IID) and risk, and injury characteristics were evaluated for the overall sample and by gender. Pearson chi-square or Fisher's exact tests and independent-sample t tests were used to test between-group differences. We found that 486 PARIs were reported totally by 289 participants, with an overall IID of 0.57 per 1000hours of exposure (males: 1.07, females: 0.45) and an injury risk of 0.34 injuries/student/y (males: 0.52; females: 0.28). Higher IIDs were found in roller skating, football, and basketball. The majority of injuries occurred outdoors and involved the lower extremities, with sprain and strain being the primary injury types. Moreover, most injuries were new, acute, and happened in non-contact situations. Of all injuries, 52.1% required medical attention and 64.6% resulted in inactivity of one or more days. Some significant differences were observed between males and females. Our study indicates that PARI is a public health concern among Chinese university students, which can provide direction for targeted prophylactic interventions to underpin the sex-specific injury mechanism to reduce PARI.

An approach to generate noncontact ACL-injury prone situations on a computer using kinematic data of non-injury situations and Monte Carlo simulation

ACL-injuries are one of the most common knee injuries in noncontact sports. Kinematic data of injury prone situations provide important information to study the underlying ACL-injury mechanisms. However, these data are rare. In this work an approach is presented to generate injury prone situations for noncontact ACL-injuries on a computer. The injury prone situations are generated by a musculoskeletal simulation model using kinematic data of a non-injury situation and the method of Monte Carlo simulation. The approach is successfully applied to generate injury prone landings in downhill ski racing. The characteristics of the obtained injury prone landings are consistent with video recordings of injury cases.

Mechanisms of acute adductor longus injuries in male football players: a systematic visual video analysis

BackgroundChange of direction and kicking have been described as the main actions resulting in adductor longus injury. Video descriptions of inciting events are lacking.ObjectivePerform a standardised visual video analysis of...

Hip and Ankle Kinematics in Noncontact Anterior Cruciate Ligament Injury Situations: Video Analysis Using Model-Based Image Matching

Background: Detailed kinematic descriptions of real anterior cruciate ligament (ACL) injury situations are limited to the knee only. Purpose: To describe hip and ankle kinematics as well as foot position relative to the center of mass (COM) in ACL injury situations through use of a model-based image-matching (MBIM) technique. The distance between the projection of the COM on the ground and the base of support (BOS) (COM_BOS) normalized to the femur length was also evaluated. Study Design: Descriptive laboratory study. Methods: Ten ACL injury video sequences from women’s handball and basketball were analyzed. Hip and ankle joint kinematic values were obtained by use of MBIM. Results: The mean hip flexion angle was 51° (95% CI, 41° to 63°) at initial contact and remained constant over the next 40 milliseconds. The hip was internally rotated 29° (95% CI, 18° to 39°) at initial contact and remained unchanged for the next 40 milliseconds. All of the injured patients landed with a heel strike with a mean dorsiflexion angle of 2° (95% CI, –9° to 14°), before reaching a flatfooted position 20 milliseconds later. The foot position was anterior and lateral to the COM in all cases. However, none of the results showed larger COM_BOS than 1.2, which has been suggested as a criterion for ACL injury risk. Conclusions: Hip kinematic values were consistent among the 10 ACL injury situations analyzed; the hip joint remained unchanged in a flexed and internally rotated position in the phase leading up to injury, suggesting that limited energy absorption took place at the hip. In all cases, the foot contacted the ground with the heel strike. However, relatively small COM_BOS distances were found, indicating that the anterior and lateral foot placement in ACL injury situations was not different from what can be expected in noninjury game situations.

Sport Injuries and Preventive Measures in Handball / Rankininkų patiriamos traumos ir naudojamos prevencinės priemonės

The aim of the study is to define the opinion of handball coaches, team players and physiotherapists on the most common injuries and their causes in handball. Research object: sport injuries and their risk factors. Research methods: analysis of literature, questionnaire “Injury prevention in handball”, quantitative data analysis chi-square (χ2) p < 0.005. The study used an international questionnaire on “Injury Prevention in the Handball” (www.safetysport.eu). The questionnaire was translated into Lithuanian, a pilot study was carried out and a questionnaire adjusted. The questionnaire is for handball coaches, athletes and physiotherapists. A total of 348 questionnaires were sent to team players, 112 of them answered (men/women). 38 handball coaches were asked to fill out their questionnaire, 21 coaches answered and 7 physiotherapists. Respondents (athletes and coaches) are playing in the highest and student leagues. Injuries in handball are associated with poor physical preparation, and it‘s noted that the lower limb injuries mainly related to non-contact situations. The head, hands, knees, ankle injuries identified as the most common injuries in handball. Incidence rate of injuries by men 50% and women 60% among handball players, but mostly there were affected lower limbs. By playing positions, the wing players affected ankle, knee and hand injuries, which is caused by jumping, landing or contact situation. Most injuries affect knees and ankle of the backcourt players, which happens in jumping, deceptive movements, running, and contact situations. The pivot players get head and knees injuries when they rotating or in contact situations with other players, as goalkeepers get lower limbs injuries after jumping, landing movements. The study of various sports athletes has shown that taller athletes are more likely to be injured than shorter athletes. Physical fatigue may be associated with decreased neuromuscular and sensory control, which may result in lower limb injury. The analysis of literature and questionnaire data of handball coaches and athletes experience showed that the most sensitive part of the body for injury in handball are lower limbs. Mostly affected parts are knees, ankles, fingers. Respondents indicated the most important causes of injuries are inappropriate warm-up, contact situations, poor physical condition, previous and accidental injuries. Keywords: injury, preventative measures, handball. DOI: http://dx.doi.org/10.15823/sm.2017.29

Identification and risk estimation of movement strategies during cutting maneuvers.

Approximately 70% of anterior cruciate ligament (ACL) injuries occur in non-contact situations during cutting and landing maneuvers. Parameters such as footstrike patterns and trunk orientation were found to influence ACL relevant knee loading, however, the relationship between the whole body movement and injury risk is debated. This study identifies whole body movement strategies that increase injury risk, and provides training recommendations to reduce this risk or enable a save return to sports after injury. Experimental cross-sectional study design. Three dimensional movement analysis was carried out to investigate 50 participants performing anticipated 90° cutting maneuvers. To identify and characterize movement strategies, footstrike pattern, knee valgus moment, knee internal rotation moment, angle of attack, shoulder and pelvis axis were analyzed using statistical parametric mapping. Three different movement strategies were identified. One strategy included rearfoot striking in combination with a relatively upright body position which generated higher knee joint loads than the second strategy, forefoot striking in combination with more backwards leaning and pre-rotation of the trunk towards the new movement direction. A third strategy combined forefoot striking with less preorientation which increased the ACL relevant knee joint load compared to the second strategy. The identified movement strategies clearly pre-determine the injury risk during non-contact situations with the third strategy as the most unfavorable one. Compared to the study of isolated parameters, the analysis of the whole body movement allowed for detailed separation of more risky from less risky cutting strategies. These results give practical recommendations for the prevention of ACL injury.

&lt;i&gt;Wh&lt;/i&gt;-questions in Singapore English tell us what about questions with declarative syntax?

Bobaljik &amp;amp; Wurmband (2015) have recently developed a hypothesis that no language truly mixes wh-movement and wh-in-situ structures in its syntax, with seemingly optional wh-in-situ in a wh-movement language being analyzed as a question with declarative syntax. In this paper, we will present novel data from Colloquial Singapore English (CSE) which question this hypothesis. Instead of assuming that the Q-feature of the interrogative CWH head in a language must be specified in a binary manner (valued or unvalued), we will propose that this feature is underspecified in languages such as CSE. The proposed amendment is not only sufficiently restrictive to cover the type of languages predicted by B&amp;amp;W’s original hypothesis, but also flexible enough to accommodate languages with a mixed wh-system. We will further argue that contact-based explanations, though plausible, do not have to be taken as a reason for CSE to develop this specific trait, which could have developed under independent, non-contact situations. This position is supported by Malay and Ancash Quechua, two non-contact languages which nonetheless exhibit optional wh-in-situ like CSE.

Effect of Fatigue Protocols on Lower Limb Neuromuscular Function and Implications for Anterior Cruciate Ligament Injury Prevention Training: A Systematic Review

Background: Approximately two-thirds of anterior cruciate ligament (ACL) tears are sustained during noncontact situations when an athlete is cutting, pivoting, decelerating, or landing from a jump. Some investigators have postulated that fatigue may result in deleterious alterations in lower limb biomechanics during these activities that could increase the risk of noncontact ACL injuries. However, prior studies have noted a wide variation in fatigue protocols, athletic tasks studied, and effects of fatigue on lower limb kinetics and kinematics. Purpose: First, to determine if fatigue uniformly alters lower limb biomechanics during athletic tasks that are associated with noncontact ACL injuries. Second, to determine if changes should be made in ACL injury prevention training programs to alter the deleterious effects of fatigue on lower limb kinetics and kinematics. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review of the literature using MEDLINE was performed. Key terms were fatigue, neuromuscular, exercise, hop test, and single-legged function tests. Inclusion criteria were original research studies involving healthy participants, use of a fatigue protocol, study of at least 1 lower limb task that involved landing from a hop or jump or cutting, and analysis of at least 1 biomechanical variable. Results: Thirty-seven studies involving 806 athletes (485 female, 321 male; mean age, 22.7 years) met the inclusion criteria. General fatigue protocols were used in 20 investigations, peripheral protocols were used in 17 studies, and 21 different athletic tasks were studied (13 single-legged, 8 double-legged). There was no consistency among investigations regarding the effects of fatigue on hip, knee, or ankle joint angles and moments or surface electromyography muscle activation patterns. The fatigue protocols typically did not produce statistically significant changes in ground-reaction forces. Conclusion: Published fatigue protocols did not uniformly produce alterations in lower limb neuromuscular factors that heighten the risk of noncontact ACL injuries. Therefore, justification does not currently exist for major changes in ACL injury prevention training programs to account for potential fatigue effects. However, the effect of fatigue related to ACL injuries is worthy of further investigation, including the refinement of protocols and methods of analysis.

Differences in the Dominant and Non-Dominant Knee Valgus Angle in Junior Elite and Amateur Soccer Players after Unilateral Landing.

More than 70% of all knee injuries in soccer occur in non-contact situations. It is known that increased lower limb dynamic knee valgus is associated with such situations. Little has been found out about differences in knee kinematics of the dominant (kicking) and non-dominant (supporting) leg during a single leg landing. A total of 114 male adolescent soccer players (age 14.6 ± 1.1 years) from elite (N = 66) and amateur soccer clubs (N = 48) performed a single leg drop landing down from a box. For each leg, the two-dimensional dynamic knee valgus angle (DKVA) was calculated. Paired t-tests were used to statistically determine significant differences between dominant and non-dominant leg DKVA, and t-tests were calculated between the two performance groups. Statistically significant differences (p < 0.05) were identified for the DKVA between the dominant and non-dominant leg for both amateur and elite players, showing a greater DKVA for the dominant leg. Group differences for the DKVA between amateur and elite players were not found, neither for the dominant, nor for the non-dominant leg. It can be concluded that the non-dominant leg showed more stable dynamics than the dominant leg during unilateral landing regardless of the player’s performance level. This could be due to adaptions to sport-specific requirements. Therefore, it is recommended that programs to prevent knee injuries among soccer players consider the dynamics of each leg individually.

The Effect of Arm Position on Lower Extremity Kinematics during a Single Limb Drop Landing: A Preliminary Study

Anterior cruciate ligament (ACL) injuries occur most commonly during non-contact situations, such as landing from a jump. Arm position has been shown to affect the loading of the lower extremity and therefore alter the potential injury risk. This study aimed to investigate the effect of arm position on lower extremity kinematics during single limb drop landings. Eight recreational American football players performed single limb drop landings on their preferential limb in four different conditions; (1) control (arms free); (2) arms to landing limb side; (3) arms in front of body; and (4) arms away from landing limb side. Kinematics of the hip, knee and ankle were recorded in both the sagittal and frontal planes at initial ground contact and maximum. Results showed that there was a significant decrease in maximum hip flexion and a significant increase in peak dorsiflexion when landing with arms away from the landing-side limb. Since decreased hip flexion and increased ankle dorsiflexion have been proposed to increase the likelihood of ACL injury, it would appear that landing with arms away from the landing-side limb may increase the risk of ACL injury, and therefore athletes should avoid this position when landing from a jump.

Male-Female Differences in Knee Laxity and Stiffness

Background: It has been reported that over 70% of anterior cruciate ligament (ACL) injuries occur in noncontact situations and that females are at 2 to 8 times greater risk of ACL injury than males. Increased joint laxity and reduced knee stiffness in female knees have been suggested as possible explanations for the higher ACL injury rates in females. Hypothesis: Compared with male knees, female knees will demonstrate increased laxity and reduced stiffness along the anterior-posterior (AP), internal-external (IE), and varus-valgus (VV) directions. Study Design: Controlled laboratory study. Methods: Forty-seven fresh-frozen human cadaveric knees were tested (22 male and 25 female) by use of a robotic system. Mean ages were 34.6 years (range, 19-45 years) for males and 28.4 years (range, 16-42 years) for females. Joint laxity and stiffness were measured from force-vs-displacement or torque-vs-rotation curves recorded for 3 modes of testing: ±134 N AP force, ±5 N·m IE torque, and ±10 N·m VV moment. Results: Compared with male knees, female knees had greater internal laxity from 0° to 50° flexion (P < .01; maximum difference of 8.3° at 50° of flexion) and greater valgus laxity from 0° to 50° of flexion (P < .05; maximum difference of 1.6° at 50° of flexion). However, female knees exhibited greater anterior laxity only at 50° of flexion (P < .03; difference of 1.3 mm). No significant male-female differences in anterior or posterior stiffness were found. Male knees had 42% greater internal stiffness from 0° to 30° of flexion (P < .03), 35% greater valgus stiffness at 10° of flexion (P < .03), and 19% greater varus stiffness at 50° of flexion (P < .03). Conclusion: Female knees demonstrated significantly increased laxity and reduced stiffness compared with males. This finding was not uniform but was dependent on the direction tested and the knee flexion angle. Clinical Relevance: Understanding the risk factors for noncontact ACL injury is important for injury prevention. In combination with other female-specific risk factors, increased knee laxity may be a contributing factor associated with the higher rate of female ACL injuries.