Landing Technique Affects Knee Loading and Position During Athletic Tasks

Anterior cruciate ligament (ACL) injuries have been reported to occur with the ankle in a dorsiflexed position at initial contact. Few studies have attempted to quantify the biomechanical parameters related with such landing patterns during athletic tasks. Objectives- The purpose of this study was to evaluate the effects that two landing techniques have in lower extremity biomechanics while performing two tasks. Design- Single-group repeated measures design. Methods- Twenty female soccer athletes from a Division 1 institution performed two landing techniques (forefoot and rearfoot) during two unanticipated tasks (sidestep cutting and pivot). Repeated measures analyses of variance were conducted to assess differences in the kinematic and kinetic parameters between landing techniques for each task. Results: The forefoot landing technique had significantly higher internal knee adductor moment than the rearfoot for both the pivot and sidestep cutting task (p \u3c 0.001 and p = 0.003, respectively). For the sidestep cutting task, participants had increased knee valgus angle with the rearfoot, whereas for the pivot they had increased knee valgus with the forefoot landing technique (p \u3c 0.05). Conclusions- The results of this study highlighted that there are inherent differences in biomechanical outcomes between foot-landing techniques. The forefoot landing technique increasingly affects knee adduction moment loading, which can potentially place a higher strain on the ACL. Essentially, the demands of the landing technique on lower extremity biomechanics (e.g., hip and knee) are task dependent

Curricular Satisfaction Levels of National Athletic Trainers\u27 Association- Accredited Postprofessional Athletic Training Graduates

Context: Academic programs rely on outcomes assessments to determine if changes in the curriculum are necessary. Objective: To examine the overall satisfaction levels of graduates (2005-2006) of National Athletic Trainers\u27 Association-accredited postprofessional athletic training education programs as related to the 2002 Standards and Guidelines for Development and Implementation of NATA-Accredited PostProfessional Graduate Athletic Training Education Programs. Design: Original survey instrument and demographic questionnaire. Setting: Online survey instrument. Patients or Other Participants: Of 211 survey recipients, 123 returned surveys (58.29% response rate). Main Outcome Measure(s): Demographic information and satisfaction levels in 10 standard areas (depth of learning, breadth of learning, critical thinking, instructor availability, theoretic basis, writing skills, scholarly growth, community return, leadership, and overall program satisfaction) were obtained. Satisfaction scores were categorized into 10 percentage brackets (eg, 80%-89%) for each standard area. Results: No differences were noted in relation to any of the standard satisfaction areas for evaluation of time off from school. However, graduates who required more than the allotted amount of time to complete their degree were less satisfied in the areas of depth of learning (P = .027), breadth of learning (P = .001), instructor availability (P = .005), writing (P = .022), and overall program satisfaction (P = .016). Conclusions: Graduates were generally satisfied across all areas of their didactic curriculum. However, satisfaction levels were affected if graduates required more than the allotted amount of time to complete their degrees

Changes in Lower Extremity Biomechanics Due to a Short-Term Fatigue Protocol

Context: Noncontact anterior cruciate ligament injury has been reported to occur during the later stages of a game when fatigue is most likely present. Few researchers have focused on progressive changes in lower extremity biomechanics that occur throughout fatiguing. Objective: To evaluate the effects of a sequential fatigue protocol on lower extremity biomechanics during a sidestep-cutting task (SS). Design: Controlled laboratory study. Setting: Laboratory. Patients or Other Participants: Eighteen uninjured female collegiate soccer players (age 19.2 ± 0.9 years, height = 1.66 ± 0.5 m, mass 61.6 ± 5.1 kg) volunteered. Intervention(s): The independent variable was fatigue level, with 3 levels (prefatigue, 50% fatigue, and 100% fatigue). Using 3-dimensional motion capture, we assessed lower extremity biomechanics during the SS. Participants alternated between a fatigue protocol that solicited different muscle groups and mimicked actual sport situations and unanticipated SS trials. The process was repeated until fatigue was attained. Main Outcome Measure(s): Dependent variables were hip- and knee-flexion and abduction angles and internal moments measured at initial contact and peak stance and defined as measures obtained between 0% and 50% of stance phase. Results: Knee-flexion angle decreased from prefatigue (-17 degrees ± 5 degrees) to 50% fatigue (-16 degrees ± 6 degrees) and to 100% fatigue (-14 degrees ± 4 degrees) (F2,34 = 5.112, P = .004). Knee flexion at peak stance increased from prefatigue (-52.9 degrees ± 5.6 degrees) to 50% fatigue (-56.1 degrees ± 7.2 degrees) but decreased from 50% to 100% fatigue (-50.5 degrees ± 7.1 degrees) (F2,34 = 8.282, P = 001). Knee-adduction moment at peak stance increased from prefatigue (0.49 ± 0.23 Nm/kgm) to 50% fatigue (0.55 ± 0.25 Nm/kgm) but decreased from 50% to 100% fatigue (0.37 ± 0.24) (F 2,34 = 3.755, P = 03). Hip-flexion angle increased from prefatigue (45.4 degrees ± 10.9 degrees) to 50% fatigue (46.2 degrees ± 11.2 degrees) but decreased from 50% to 100% fatigue (40.9 degrees ± 11.3 degrees) (F2,34 = 6.542, P= .004). Hip flexion at peak stance increased from prefatigue (49.8 degrees ± 9.9 degrees) to 50% fatigue (52.9 degrees ± 12.1 degrees) but decreased from 50% to 100% fatigue (46.3 degrees ± 12.9 degrees) (F 2,34 = 8.639, P = 001). Hip-abduction angle at initial contact decreased from prefatigue (-13.8 degrees ± 6.6 degrees) to 50% fatigue (-9.1 degrees ± 6.5 degrees) and to 100% fatigue (-7.8 degrees ± 6.5 degrees) (F2,34 = 11.228, P = .001). Hip-adduction moment decreased from prefatigue (0.14 ± 0.13 Nm/kgm) to 50% fatigue (0.08 ± 0.13 Nm/kgm) and to 100% fatigue (0.06 ± 0.05 Nm/ kg) (F2,34 = 5.767, P = .007). Conclusions: The detrimental effects of fatigue on sagittal and frontal mechanics of the hip and knee were visible at 50% of the participants\u27 maximal fatigue and became more marked at 100% fatigue. Anterior cruciate ligament injury-prevention programs should emphasize feedback on proper mechanics throughout an entire practice and not only at the beginning of practice

Differences in Static postural Control Performance Between Athletes who are Hearing and Athletes who are Deaf or Hard-of-Hearing

Please enjoy Volume 5, Issue 1 of the JSMAHS. In this issue you will find Professional and under graduate research abstracts, case reports, and critically appraised topics. This research was funded by an OATA Research Grant Thank you for viewing this 5th Annual OATA Special Edition

Comparison of a Head Mounted Impact Measurement Device to the Hybrid III Anthropomorphic Testing Device in a Controlled Laboratory Setting

Background: Reports estimate that 1.6 to 3.8 million cases of concussion occur in sports and recreation each year in the United States. Despite continued efforts to reduce the occurrence of concussion, the rate of diagnosis continues to increase. The mechanisms of concussion are thought to involve linear and rotational head accelerations and velocities. One method of quantifying the kinematics experienced during sport participation is to place measurement devices into the athlete’s helmet or directly on the athlete’s head. Purpose: The purpose of this research to determine the accuracy of a head mounted device for measuring the head accelerations experienced by the wearer. This will be accomplished by identifying the error in Peak Linear Acceleration (PLA), Peak Rotational Acceleration (PRA) and Peak Rotational Velocity (PRV) of the device. Study Design: Laboratory study. Methods: A helmeted Hybrid III 50th percentile male headform was impacted via a pneumatic ram from the front, side, rear, front oblique and rear oblique at speeds from 1.5 to 5 m/s. The X2 Biosystems xPatch® (Seattle, WA) sensor was placed on the headform’s right side at the approximate location of the mastoid process. Measures of PLA, PRA, PRV from the xPatch ® and Hybrid III were analyzed for Root Mean Square Error (RMSE), and Absolute and Relative Error (AE, RE). Result: Seventy-six impacts were analyzed. All measures of correlation, fixed through the origin, were found to be strong: PLA R2 =0.967 p \u3c 0.01, PRA R2 =0.933 p \u3c 0.01, PRV R2 =0.999 p \u3c 0.00. PLA RMSE was 34%, RE 31.0% ± 14.0, and AE 31.1% ± 13.7. PRA RMSE was 23.4%, RE -6.7 ± 22.4 and AE 18.9% ± 13.8. PRV RMSE was 2.2%, RE 0.1 ± 2.2, and AE 1.8 ± 1.3. Conclusion: Without including corrections for effect of skin artifact, the xPatch® produces measurements highly correlated with the gold standard yet above the average error of testing devices in both PLA and PRA, but a low error in PRV. PLA measures from the xPatch® system demonstrated a high level of correlation with the PLA data from the Hybrid III mounted data collection system. Level of Evidence:

Effects of Training on Physical Performance Wearing Personal Protective Equipment

We evaluated the effects of wearing a weighted vest during 6 weeks of military-style training. Forty-three subjects were randomly assigned to a control group or a vest group (carrying 4-5 kg for 2 weeks, and 8-10 kg for 4 weeks), with 37 completing the study (17 vest, 20 control). Both groups performed stair climbing in addition to standard Marine Corps training for 1 hour, four times per week. Pre- and post-tests were performed while wearing military personal protective equipment, with the exception of the Marine Physical Readiness Test (PRT). Both groups significantly improved PRT scores (8.4% 3-mile run, 28-38% calisthenics) and an agility drill (4.4%). Significant improvements in uphill treadmill performance (6.8% vest, 3.0% control) and maximal oxygen consumption (10.7% vest, 6.8% control) were approximately twice as much in the vest versus control group, although these differences did not reach significance (p = 0.16 and 0.13, respectively)

Instruction and Jump-Landing Kinematics in College-Aged Female Athletes Over Time

Context: Instruction can be used to alter the biomechanical movement patterns associated with anterior cruciate ligament (ACL) injuries. Objective: To determine the effects of instruction through combination (self and expert) feedback or self-feedback on lower extremity kinematics during the box–drop-jump task, running–stop-jump task, and sidestep-cutting maneuver over time in college-aged female athletes. Design: Randomized controlled clinical trial. Setting: Laboratory. Patients or Other Participants: Forty-three physically active women (age = 21.47 ± 1.55 years, height = 1.65 ± 0.08 m, mass = 63.78 ± 12.00 kg) with no history of ACL or lower extremity injuries or surgery in the 2 months before the study were assigned randomly to 3 groups: self-feedback (SE), combination feedback (CB), or control (CT). Intervention(s): Participants performed a box–drop-jump task for the pretest and then received feedback about their landing mechanics. After the intervention, they performed an immediate posttest of the box–drop-jump task and a running–stop-jump transfer test. Participants returned 1 month later for a retention test of each task and a sidestep-cutting maneuver. Kinematic data were collected with an 8-camera system sampled at 500 Hz. Main Outcome Measure(s): The independent variables were feedback group (3), test time (3), and task (3). The dependent variables were knee- and hip-flexion, knee-valgus, and hip- abduction kinematics at initial contact and at peak knee flexion. Results: For the box–drop-jump task, knee- and hip-flexion angles at initial contact were greater at the posttest than at the retention test (P \u3c .001). At peak knee flexion, hip flexion was greater at the posttest than at the pretest (P = .003) and was greater at the retention test than at the pretest (P = .04); knee valgus was greater at the retention test than at the pretest (P = .03) and posttest (P = .02). Peak knee flexion was greater for the CB than the SE group (P = .03) during the box–drop-jump task at posttest. For the running–stop-jump task at the posttest, the CB group had greater peak knee flexion than the SE and CT (P ≤ .05). Conclusions: Our results suggest that feedback involving a combination of self-feedback and expert video feedback with oral instruction effectively improved lower extremity kinematics during jump-landing tasks

Inter-Rater Agreement and Validity of a Tackling Performance Assessment Scale in Youth American Football

Background: Long term neurologic injury and concussion have been identified as risks from participation in American football. Altering tackling form has been recommended to reduce the risk of neurologic injury caused by head accelerations when tackling. The purpose of this research is to determine the inter-rater agreement and validity of the Qualitative Youth Tackling System (QYTS), a six-item feedback scale to correct tackling form, when utilized by novice and expert raters. Hypothesis: Experienced raters will have higher levels of agreement with each other and with motion capture when compared to novice raters. Methods: Both novice and experienced raters viewed video of youth athletes (ages 9-13) tackling a dummy in a laboratory setting along. The raters identified successful performance according to a binary rating scale for each component. Analysis of both the raters\u27 agreement with each other and with an objective motion capture measure were completed. Results: Fliess\u27 Kappa measures between all raters were found to be moderate for head placement (k=.48), fair for cervical extension (k=.38), trunk inclination (k=.37), shoulder extension (k=.27) and step length (k=.29), and there was no agreement for pelvic height (k=.-16). When compared to the dichotomized validation measures of each of the five components provided by the motion capture system the average Cohen\u27s Kappa agreement was substantial for pelvic height (k=.63), fair for step length (k=.34), cervical extension (k=.40), trunk inclination (k=.35), and slight for shoulder extension (k=.16). The experienced raters out-performed the novice raters in all categories. Conclusion: The results of this study indicate that skilled raters are better able to identify the movement patterns included in the QYTS when compared to a validation measure as well have higher rates of interrater agreement than novice raters. Level of Evidence: 3

The Effect of Tackling Training on Head Accelerations in Youth American Football

Background: Many organizations have introduced frameworks to reduce the incidence of football related concussions through proper equipment fitting, coach education, and alteration of tackling technique. Purpose: The purpose of this study was to examine the effects of training in a vertical, head up tackling style on the number of head accelerations experienced while tackling in a controlled laboratory situation. The authors hypothesized that training in a head up tackling technique would reduce the severity of head acceleration experienced by participants. Design: Controlled Laboratory Study. Methods: Twenty-four participants (11.5 ± 0.6 years old, 60.5 ± 2.2 in, 110 ± 18.4 lbs.) with previous playing experience completed a one-day training session on tackling technique utilizing a tackling dummy. A subgroup of these participants completed an additional two days of training with a 48 hour retention test. Head accelerations were analyzed at baseline and end of training. Feedback consisted of verbal feedback utilizing the Qualitative Youth Tackling Scale (QYTS) and video tackling playback. Results: A significant reduction in the number of peak linear head accelerations over 10 g and peak rotational head accelerations over 1885 deg/s² were found in dummy tackling after training in both the one day and three day training regimens. A significant change in QYTS tackling form score was found between pretest and post-test (p=0.004). Participants with larger steps had a 2.28, 4.42 and 4.14 increased odds ratio of sustaining head accelerations over 10, 15 and 20 g respectively. Conclusions: Training in a vertical, head up tackling style decreased the number of head accelerations over threshold values sustained while tackling; decreased step length may be the driving factor in the effectiveness of this tackling form. Level of Evidence: Level 3

Epidemiology of Knee Sprains in Youth, High School, and Collegiate American Football Players

Context: Assessment of health-related quality of life (HRQOL) after injury is important. Differences in HRQOL between nonathletes and athletes and between injured and uninjured athletes have been demonstrated; however, the evidence has not been synthesized. Objective: To answer the following questions: (1) Does HRQOL differ among adolescent and collegiate athletes and nonathletes? (2) Does HRQOL differ between injured adolescent and collegiate athletes or between athletes with a history of injury and uninjured athletes or those without a history of injury? Data Sources: We systematically searched CINAHL, MEDLINE, SPORTDiscus, and PubMed. A hand search of references was also conducted. Study Selection: Studies were included if they used generic instruments to compare HRQOL outcomes between athletes and nonathletes and between uninjured and injured athletes. Studies were excluded if they did not use a generic instrument, pertained to instrument development, or included retired athletes or athletes with a chronic disease. Data Extraction: We assessed study quality using the modified Downs and Black Index Tool. Bias-corrected Hedges g effect sizes and 95% confidence intervals (CIs) were calculated. The Strength of Recommendation Taxonomy (SORT) was used to determine the overall strength of the recommendation. A random-effects meta-analysis was performed for all studies using the composite or total score. Data Synthesis: Eight studies with modified Downs and Black scores ranging from 70.6% to 88.4% were included. For question 1, the overall random-effects meta-analysis was weak (effect size = 0.27, 95% confidence interval = 0.14, 0.40; P \u3c .001). For question 2, the overall random-effects meta-analysis was moderate (effect size = 0.68, 95% confidence interval = 0.42, 0.95; P \u3c .001). Conclusions: Grade A evidence indicates that athletes reported better HRQOL than nonathletes and that uninjured athletes reported better HRQOL than injured athletes. However, the overall effect for question 1 was weak, suggesting that the differences between athletes and nonathletes may not be clinically meaningful. Clinicians should monitor HRQOL after injury to ensure that all dimensions of health are appropriately treated