Ground reaction force (GRF) and tibiofemoral force magnitudes and directions have been shown to affect anterior cruciate ligament loading during landing. However, the kinematic and kinetic factors modifying these 2 forces during landing are unknown. To clarify the intersegmental kinematic and kinetic links underlying the alteration of the GRF and tibiofemoral force vectors secondary to changes in the sagittal-plane body position during single-legged landing. Crossover study. Laboratory. Twenty recreationally active participants (age = 23.4 ± 3.6 years, height = 171.0 ± 9.4 cm, mass = 73.3 ± 12.7 kg). Participants performed single-legged landings using 3 landing styles: self-selected landing (SSL), body leaning forward and landing on the toes (LFL), and body upright with flat-footed landing (URL). Three-dimensional kinetics and kinematics were recorded. Sagittal-plane tibial inclination and knee-flexion angles, GRF magnitude and inclination angles relative to the tibia, and proximal tibial forces at peak tibial axial forces. The URL resulted in less time to peak tibial axial forces, smaller knee-flexion angles, and greater magnitude and a more anteriorly inclined GRF vector relative to the tibia than did the SSL. These changes led to the greatest peak tibial axial and anterior shear forces in the URL among the 3 landing styles. Conversely, the LFL resulted in longer time to peak tibial axial forces, greater knee-flexion angles, and reduced magnitude and a more posteriorly inclined GRF vector relative to the tibia than the SSL. These changes in LFL resulted in the lowest peak tibial axial and largest posterior shear forces among the 3 landing styles. Sagittal-plane intersegmental kinematic and kinetic links strongly affected the magnitude and direction of GRF and tibiofemoral forces during the impact phase of single-legged landing. Therefore, improving sagittal-plane landing mechanics is important in reducing harmful magnitudes and directions of impact forces on the anterior cruciate ligament.Context:
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Altered Vertical Ground Reaction Forces in Participants With Chronic Ankle Instability While Running
Altered gait kinetics may increase the risk of long-term injuries in participants with chronic ankle instability (CAI). Vertical ground reaction forces (vGRFs) can provide insight into how body loading is altered. To compare the components of vGRFs while running in participants with or without CAI. Cohort study. University biomechanics laboratory. Twenty-four experienced, college-aged runners. Groups were categorized by the presence (CAI group) or absence (control group) of CAI through self-reported questionnaires. After a warm-up period, all participants ran on an instrumented treadmill for 5 minutes at 3.3 m/s. Data were collected during the last 30 seconds. Five continuous trials of heel-to-toe running were identified per participant and averaged for statistical analysis. The dependent variables were impact peak force (N/body weight [BW]), active peak force (N/BW), time to impact peak force (milliseconds), time to active peak force (milliseconds), and average loading rate ([N/BW]/s). A difference was found between groups (P = .002). The CAI group had higher impact peak forces (P = .001) and active peak forces (P = .002) compared with the control group. The CAI group also had an increased loading rate (P = .001) and a shorter time to reach the active peak force (P = .001) compared with the control group. No difference was seen between groups in the time to reach the impact peak force (P = .952). Participants with CAI produced altered vGRFs and loading rates while running. Altered loading rates could predispose individuals with CAI to stress-related injuries and repetitive sprains.Context:
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Neuromuscular training enhances unconscious motor responses by stimulating both the afferent signals and central mechanisms responsible for dynamic joint control. Dynamic joint-control training is a vital component of injury-prevention programs. To investigate the effects of body-weight neuromuscular training on Y-Balance Test (YBT) performance and postural control in female basketball players. Randomized controlled clinical trial. Basketball practice sessions. A total of 28 healthy elite female basketball players were randomly assigned to an experimental (n = 14) or a control group (n = 14). Before their regular practice sessions, the experimental group warmed up with body-weight neuromuscular exercises and the control group with standard tactical-technical exercises twice weekly for 8 weeks. Anterior-, posteromedial-, and posterolateral-reach and composite YBT scores were measured before and after 8 weeks of training. Improvement over baseline scores was noted in the posteromedial (right = 86.5 ± 4.5 cm versus 89.6 ± 2.2 cm, +3.5%, P = .049; left = 85.5 ± 4.3 cm versus 90.2 ± 2.7 cm, +5.5%, P = .038)- and posterolateral (right = 90.7 ± 3.6 cm versus 94.0 ± 2.7 cm, +3.6%, P = .016; left = 90.9 ± 3.5 cm versus 94.2 ± 2.6 cm, +3.6%, P = .011)-reach directions and in the composite YBT scores (right = 88.6% ± 3.2% versus 94.0% ± 1.8%, +5.4%, P = .0004; left = 89.2% ± 3.2% versus 94.5% ± 3.0%, +5.8%, P = .001) of the experimental group. No differences in anterior reach were detected in either group. Differences were noted in postintervention scores for posteromedial reach (right = 89.6 ± 2.2 cm versus 84.3 ± 4.4 cm, +4.1%, P = .005; left = 94.2 ± 2.6 cm versus 84.8 ± 4.4 cm, +10%, P = .003) and composite scores (right = 94.0% ± 1.8% versus 87.3% ± 2.0%, +7.1%, P = .003; left = 94.8% ± 3.0% versus 87.9% ± 3.4%, +7.3%, P < .0001) between the experimental and control groups. Body-weight neuromuscular training improved postural control and lower limb stability in female basketball players as assessed with the YBT. Incorporating neuromuscular training into the workout routines for basketball players may enhance joint awareness and reduce the risk of lower extremity injury.Context:
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Sunscreen lotions are important to protect the skin during outdoor exercise, but they may interfere with sweating. To measure the effect of 2 water-resistant sunscreens on local sweat production in men and women exercising in the heat and to compare those effects with the expected inhibition resulting from the use of an antiperspirant. Randomized crossover study. Exercise in the heat (ambient temperature = 30.2°C ± 0.4°C dry bulb and 58% ± 4.3% relative humidity) in a controlled-environment laboratory. Twenty physically active, apparently healthy college students, 10 men (age = 22.5 ± 2.8 years, height = 1.771 ± 0.069 m, mass = 70.2 ± 11.0 kg) and 10 women (age = 22.2 ± 3.2 years, height = 1.625 ± 0.075 m, mass = 57.7 ± 7.9 kg). With sweat-collection patches applied to their right and left scapular regions, the participants performed 2 exercise sessions on consecutive days. We assigned skin treatments (antiperspirant; organic chemical sun filter, sunscreen A; inorganic physical sun block, sunscreen B; no lotion) randomly to side and session. Participants pedaled at 79% ± 1% of maximum heart rate for 20 minutes in the heat. Scapular localized sweat rate. No baseline, environmental, or exercise condition was different among skin treatments. Scapular localized sweat rate was lower for the antiperspirant treatment (88.3 μL/min·dm2; 95% confidence interval [CI] = 82.0, 94.7 μL/min·dm2) and the inorganic physical sun block (sunscreen B) treatment (99.3 μL/min·dm2; 95% CI = 93.1, 105.5 μL/min·dm2) than for the organic chemical sun filter (sunscreen A) treatment (114.8 μL/min·dm2; 95% CI = 108.8, 120.6 μL/min·dm2) or the no-lotion treatment (122.6 μL/min·dm2; 95% CI = 116.2, 129.0 μL/min·dm2; P < .01). The inorganic physical sun block, sunscreen B, hindered effective sweating to the same extent as the antiperspirant, whereas the treatment with the organic chemical sun filter, sunscreen A, was not different from the control treatment. At this stage, it is not possible to identify the specific ingredient responsible for the effect.Context:
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The pocketing effect of helmet padding helps to dissipate forces experienced by the head, but if the player's helmet remains stationary in an opponent's shoulder pads, the compressive force on the cervical spine may increase. To (1) measure the coefficient of static friction between different football helmet finishes and football jersey fabrics and (2) calculate the potential amount of force on a player's helmet due to the amount of friction present. Cross-sectional study. Laboratory. Helmets with different finishes and different football jersey fabrics. The coefficient of friction was determined for 2 helmet samples (glossy and matte), 3 football jerseys (collegiate, high school, and youth), and 3 types of jersey numbers (silkscreened, sublimated, and stitched on) using the TAPPI T 815 standard method. These measurements determined which helmet-to-helmet, helmet-to-jersey number, and helmet-to-jersey material combination resulted in the least amount of static friction. The glossy helmet versus glossy helmet combination produced a greater amount of static friction than the other 2 helmet combinations (P = .013). The glossy helmet versus collegiate jersey combination produced a greater amount of static friction than the other helmet-to-jersey material combinations (P < .01). The glossy helmet versus silkscreened numbers combination produced a greater amount of static friction than the other helmet-to-jersey number combinations (P < .01). The force of static friction experienced during collisions can be clinically relevant. Conditions with higher coefficients of static friction result in greater forces. In this study, the highest coefficient of friction (glossy helmet versus silkscreened number) could increase the forces on the player's helmet by 3553.88 N when compared with other helmet-to-jersey combinations. Our results indicate that the makeup of helmet and uniform materials may affect sport safety.Context:
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Workplace bullying (WPB) has recently received much attention in society. Research on WPB in athletic training practice settings is limited. To determine the prevalence of WPB in the secondary school setting and explore the factors related to it. Mixed-methods study. Secondary school. A total of 567 athletic trainers (women = 322 [56.8%], men = 245 [43.2%]), aged 36.5 ± 11.1 years with 11.9 ± 9.5 years of experience took part in phase I. Ten participants (7 women and 3 men), aged 39.3 ± 10.1 years with 14.3 ± 8.3 years of experience, took part in phase II. For the online survey, we used the previously validated and reliable (Cronbach α = .84) Athletic Training Workplace Environment Survey, which included the Negative Acts Questionnaire-Revised. The prevalence of WPB was measured with descriptive statistics, and χ2 analyses were used to compare differences between groups (ie, females and males, perpetrators' titles). The interview data were examined using an inductive content analysis. Of the participants, 44 (7.8%) were empirically identified as targets of bullying, though a higher percentage (12.4%, n = 70) self-identified as bullying targets. Men and women did not differ with respect to having experienced WPB, but more perpetrators were male (71.6%, n = 48) than female (28.4%, n = 19; χ21 = 12.55, P = <.001). We also observed a difference in perpetrators' titles, with the vast majority of bullies being coaches or administrators (χ26 = 33.82, P = <.001). Lack of administrator support and discrimination were antecedents of bullying. Stress, depression, and sleep disturbances were reported consequences. Participants coped with bullying by avoidance and role refocusing. Bullying was experienced by a small percentage of athletic trainers in the secondary school setting, a contrast to the findings in the collegiate practice setting.Context:
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Availability of athletic trainer (AT) services in US secondary schools has recently been reported to be as high as 70%, but this only describes the public sector. The extent of AT coverage in private secondary school settings has yet to be investigated and may differ from the public secondary school setting for several reasons, including differences in funding sources. To determine the level of AT services in US private secondary schools and identify the reasons why some schools did not employ ATs. Concurrent mixed-methods study. Private secondary schools in the United States. Of 5414 private secondary schools, 2044 (38%) responded to the survey. School administrators responded to the survey via telephone or e-mail. This instrument was previously used in a study examining AT services among public secondary schools. Descriptive statistics provided national data. Open-ended questions were evaluated through content analysis. Of the 2044 schools that responded, 58% (1176/2044) offered AT services, including 28% (574/2040) full time, 25% (501/2042) part time, 4% (78/1918) per diem, and 20% (409/2042) from a hospital or clinic. A total of 84% (281 285/336 165) of athletes had access to AT services. Larger private secondary schools were more likely to have AT services available. Barriers to providing AT services in the private sector were budgetary constraints, school size and sports, and lack of awareness of the role of an AT. More than half of the surveyed private secondary schools in the United States had AT services available; however, only 28% had a full-time AT. This demonstrates the need for increased medical coverage to provide athletes in this setting the appropriate level of care. Budgetary concerns, size of the school and sport offerings, and lack of awareness of the role of the AT continued to be barriers in the secondary school setting.Context:
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The Patient-Reported Outcomes Measurement Information System (PROMIS) item banks have been validated for general populations, but their application to high-functioning patient populations remains speculative. To examine the measurement properties of the PROMIS physical function item bank, version 1.0, when applied to individuals representing high levels of physical ability. Cross-sectional study. National Collegiate Athletic Association Division I and III collegiate athletic training rooms and intramural events. A heterogeneous sample of 215 adults from Division I or Division III collegiate or recreational sports volunteered for this study. Participants were divided into 4 groups depending on sport activity and injury status: healthy collegiate (HC; 33 men, 37 women; age = 19.7 ± 1.1 years), injured and currently active in sport (IP; 21 men, 29 women; age = 19.9 ± 1.2 years), injured and currently not active in sport (INP; 12 men, 18 women; age = 19.7 ± 1.3 years), and healthy recreational (HR; 47 men, 18 women; age = 20.1 ± 1.4 years). Participants completed 2 assessments: (1) an injury-history questionnaire and (2) the PROMIS physical function item bank, version 1.0, in computer-adaptive form. Mean PROMIS physical function scores were determined for each group. The PROMIS physical function score for the HC group (61.7 ± 6.0) was higher than for the IP (54.9 ± 7.5) and INP (44.1 ± 8.2) groups (P < .001). The IP group had a higher score than the INP group (P < .001). Mean PROMIS scores were not different between the HC and HR participants (mean difference = 1.9, P = .10). The computer-adaptive PROMIS physical function item bank, version 1.0, accurately distinguished injury status in elite-level athletes on a physical function latent trait continuum. Although it was unable to distinguish HC athletes from HR athletes, exposing a possible ceiling effect, it offers potential for use as an outcome instrument for athletic trainers and other sports medicine clinicians.Context:
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Sport-specific adaptations at the glenohumeral joint could occur in adolescent athletes because they start participating in high-performance sports in early childhood. To investigate shoulder-rotator strength, internal-rotation (IR) and external-rotation (ER) range of motion (ROM), and acromiohumeral distance (AHD) in asymptomatic adolescent volleyball attackers to determine if they have risk factors for injury. Cross-sectional study. University laboratory. Thirty-nine adolescent high school-aged volleyball attackers (22 boys, 17 girls; age = 16.0 ± 1.4 years, height = 179.2 ± 9.0 cm, mass = 67.1 ± 10.9 kg, body mass index = 20.7 ± 2.6 kg/m2). Shoulder IR and ER ROM, total-rotation ROM, glenohumeral IR deficit, AHD, and concentric and eccentric strength of the shoulder internal and external rotators were tested bilaterally. External-rotation ROM was greater (t38 = 4.92, P < .001), but IR ROM (t38 = −8.61, P < .001) and total ROM (t38 = −3.55, P = .01) were less in the dominant shoulder, and 15 athletes had a glenohumeral IR deficit (IR ROM loss > 18°). We observed greater concentric internal-rotator (t38 = 2.89, P = .006) and eccentric external-rotator (t38 = 2.65, P = .01) strength in the dominant than in the nondominant shoulder. The AHD was less in the dominant shoulder (t38 = −3.60, P < .001). Adolescent volleyball attackers demonstrated decreased IR ROM, total ROM, and AHD and increased ER ROM in their dominant shoulder. Therefore, routine screening of adolescent athletes and designing training programs for hazardous adaptive changes could be important in preventing shoulder injuries.Context:
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Schneider KJ, Iverson GL, Emery CA, McCrory P, Herring SA, Meeuwisse WH. The effects of rest and treatment following sport-related concussion: a systematic review of the literature. Br J Sports Med. 2013;47(5):304–307. After concussion and a period of symptom-limited physical and cognitive rest, do athletes who experience intermittent symptoms return to asymptomatic condition more quickly with physical activity than with prolonged physical rest? One investigator performed an individual search for each research question using the following databases: CINAHL, Cochrane Controlled Trials Registers, EMBASE, HealthSTAR, ProQuest, PsychInfo, PubMed, SPORTDiscus, and Web of Science. Search terms for rest were brain concussion, cognitive rest, mild traumatic brain injury, physical exertion, postconcussive syndrome, rehabilitation, sport-related concussion, therapy, treatment, and treatment outcome. Search terms for treatment were the same terms as for rest, as well as brain training, cervical spine, cognitive therapy, dizziness, exercise, headache, neck, pharmacotherapy, postural balance, and vertigo. The authors included peer-reviewed, published articles and abstracts and performed a citation search. Studies were included based on the following criteria as determined before searching: classified as original research, symptoms resulted after sport-related concussion, and investigation of the effects of either rest or treatment on symptoms. Abstracts that were excluded failed to evaluate rest, omitted sport-related concussion as the cause of symptoms, failed to evaluate a treatment's effect on sport-related concussion, or did not present original research. The following data were extracted from each study that fit the selection criteria: study design; sample size; participants' demographic information (age and sex); type, duration, and intensity of treatment; key findings including effect sizes and means with 95% confidence intervals (calculated when possible using the data provided in the original study, even if not presented in the original study); and relevant comments. The search revealed 749 articles evaluating the effects of rest and 1175 articles evaluating the effects of treatment. Of the 749 articles evaluating the effects of rest, only 2 met all the inclusion criteria. Of the 1175 articles evaluating the effects of treatment, only 10 met all the inclusion criteria. Ultimately, the authors were able to identify additional treatment articles that met the inclusion criteria, for a total of 12. The nature of the treatments and the participants differed enough that meta-analysis was not possible. One of the 2 articles that evaluated rest was a retrospective analysis of athletes that showed those who were prescribed a period of cognitive rest had a longer duration of symptoms. The other study followed athletes postconcussion who were retrospectively assigned to groups based on self-reported activity level after injury. Those who reported moderate levels of cognitive and physical exertion over the first month postinjury appeared to demonstrate improved outcomes compared with those who pursued small or large amounts of activity. Twelve studies evaluated the effects of treatment on symptoms after sport-related concussion. Various interventions were reviewed, including pharmacotherapy, light aerobic activity, graded exercise treadmill test, hyperbaric oxygen therapy, vestibular physiotherapy, and cervical spine manual therapy. Unfortunately, the authors did not report effect sizes for specific interventions, and due to the varied nature of each study and its respective treatment approach, no pooled data could be analyzed. However, a group of adolescents treated with submaximal aerobic and coordination exercises, visualization, and imagery returned to full normal physical activity at a mean duration of 4.4 weeks (95% confidence interval = 3.1, 5.7 weeks). Furthermore, a randomized controlled trial of patients experiencing persistent neck pain, dizziness, and headaches who underwent manual and physical therapy showed they were more likely to return to sport after 8 weeks of treatment. Despite the inability to pool data, the authors concluded that each treatment appeared to positively influence specific aspects of certain patients' symptoms. Little high-quality evidence has addressed the effects of rest and treatment after sport-related concussion. Current evidence suggests that an initial period of rest appears to be beneficial. Further research is needed to evaluate the long-term outcomes of rest (including the quality and quantity of the rest). Low levels of exercise may benefit the athlete postinjury, but additional study is required to determine the optimal timing for initiation of treatment postinjury. Patients with cervical spine or vestibular dysfunction may benefit from rehabilitation techniques targeted at their individual symptom profile to facilitate recovery. Overall, we need high-quality studies evaluating resting period, pharmacologic interventions, rehabilitative techniques, and exercise and their effects on patients slow to recover from concussion symptoms.Reference:
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Reliability and Validity of the Functional Assessment of Neurocognition in Sport (FANS): A Paradigm Shift in Post-Concussion Return-to-Sport Decision-Making
Driving After Concussion: Clinical Measures Associated with Post-concussion
The role of shoulder posture in pitching mechanics and injury risk in high school baseball pitchers
Corticospinal Excitability during Standing and Its Association with Postural Control Following Acute Lateral Ankle Sprain.
The socio-economic cost of anterior cruciate ligament injuries and lateral ankle sprains in amateur football and basketball.
JAT eISSN: 1938-162X
JAT ISSN: 1062-6050
ATEJ ISSN: 1947-380X