Minimal measurement error (reliability) during the collection of interval- and ratio-type data is critically important to sports medicine research. The main components of measurement error are systematic bias (e.g. general learning or fatigue effects on the tests) and random error due to biological or mechanical variation. Both error components should be meaningfully quantified for the sports physician to relate the described error to judgements regarding ‘analytical goals’ (the requirements of the measurement tool for effective practical use) rather than the statistical significance of any reliability indicators.

Statistical Methods For Assessing Measurement Error (Reliability) in Variables Relevant to Sports Medicine

BackgroundFemale athletes participating in high-risk sports suffer anterior cruciate ligament injury at a 4- to 6-fold greater rate than do male athletes.HypothesisPrescreened female athletes with subsequent anterior cruciate ligament injury will demonstrate decreased neuromuscular control and increased valgus joint loading, predicting anterior cruciate ligament injury risk.Study DesignCohort study; Level of evidence, 2.MethodsThere were 205 female athletes in the high-risk sports of soccer, basketball, and volleyball prospectively measured for neuromuscular control using 3-dimensional kinematics (joint angles) and joint loads using kinetics (joint moments) during a jump-landing task. Analysis of variance as well as linear and logistic regression were used to isolate predictors of risk in athletes who subsequently ruptured the anterior cruciate ligament.ResultsNine athletes had a confirmed anterior cruciate ligament rupture; these 9 had significantly different knee posture and loading compared to the 196 ...

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Biomechanical Measures of Neuromuscular Control and Valgus Loading of the Knee Predict Anterior Cruciate Ligament Injury Risk in Female Athletes A Prospective Study

To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.

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The Effect of Neuromuscular Training on the Incidence of Knee Injury in Female Athletes A Prospective Study

Results: Most of the study group were women (54%). Some injuries occurred with a significantly higher frequency in one sex. Being less than 34 years old was reported as a risk factor across the sexes for patellofemoral pain syndrome, and in men for iliotibial band friction syndrome, patellar tendinopathy, and tibial stress syndrome. Being active for less than 8.5 years was positively associated with injury in both sexes for tibial stress syndrome; and women with a body mass index less than 21 kg/m 2 were at a significantly higher risk for tibial stress fractures and spinal injuries. Patellofemoral pain syndrome was the most common injury, followed by iliotibial band friction syndrome, plantar fasciitis, meniscal injuries of the knee, and tibial stress syndrome. Conclusions: Although various risk factors were shown to be positively associated with a risk for, or protection from, specific injuries, future research should include a non-injured control group and a more precise measure of weekly running distance and running experience to validate these results.

https://bjsm.bmj.com/content/bjsports/36/2/95.full.pdf

A retrospective case-control analysis of 2002 running injuries

http://www1.udel.edu/biology/rosewc/kaap686/reserve/novacheck1998_runningbiomech.pdf

The biomechanics of running.

overuse syndromes. While there is abundant literature which describes the etiology, symptoms and management of various injuries sustained by runners, there is limited information regarding the incidence and distribution of these injuries with respect to such variables as classification, site (anatomic) and competitive event (running). A knowledge of the relative incidence, treatment and results of treatment of injuries to runners should provide not only a basis for better management but also a probable basis for increased utilization of preventive measures and earlier recognition and treatment of these injuries.

Injuries to runners.

ZHANG, S-N., B. T. BATES, and J. S. DUFEK. Contributions of lower extremity joints to energy dissipation during landings. Med. Sci. Sports Exerc., Vol. 32, No. 4, pp. 812–819, 2000.Purpose:The purpose of the study was to investigate changes in lower extremity joint energy absorption for different la

Contributions of lower extremity joints to energy dissipation during landings.

The investigation of impact force attenuation during landings may help identify performance strategies. The purpose of the study was to evaluate the effects of height (three), distance (three), and technique (three) on impact forces during landings. Three male volunteer subjects were filmed while performing three right foot landings onto a force platform for each combination of height, distance, and technique for a total of 81 trials per subject. Between- and within-subject three-way ANOVAs and three regression models (mechanical, biomechanical, refined biomechanical) were computed on the dependent variables of first (F1) and second (F2) maximum vertical force. Results of the between-subject ANOVAs indicated significant (P less than 0.05) height, distance, and technique main effects for F1 and a height x technique interaction for F2. The within-subject ANOVA results identified unique models for each of the three subjects. The biomechanical regression model exhibited the best predictions of F1 and F2 for S1 (81.0 and 72.0% explained variance, respectively), while the refined biomechanical model accounted for 83.4, 81.3, 80.9, and 88.0% of the F1 and F2 variances for S2 and S3, respectively. In conclusion, the within-subject results identified unique individual landing strategies that were masked by the group analyses suggesting that caution be exercised in using between-subject analysis techniques.

The evaluation and prediction of impact forces during landings

Many sport and movement activities contain a jumping component which necessitates landing. Several injury surveys across a variety of jump sports have identified the lower extremities and specifically the knee joint as being a primary injury site. Factors which might contribute to the frequency and severity of such injuries include stresses to which the body is subjected during performance (forces and torques), body position at landing, performance execution and landing surface. Most of the initial landing studies were primarily descriptive in nature with many of the more recent efforts being directed toward identifying the specific performance factors that could account for the observed system stresses. Continued investigations into landing are necessary to more thoroughly understand the force attenuation mechanisms and critical performance variables associated with lower extremity injuries.

Biomechanical factors associated with injury during landing in jump sports.

Excessive foot pronation has been speculated to be a cause of leg and foot problems among runners. Foot orthotic devices are often used to modify this condition. Examination of the records of 180 patients treated for various running injuries showed that 83 individuals (46%) were prescribed orthotic devices and that 65 of these runners (78%) were able to return to their previous running programs. In order to assess further the effects of this type of orthotic device, six runners were selected from this group and filmed using two cameras (200 frames/sec) under three conditions: (1) barefoot, (2) regular shoe, and (3) regular shoe plus orthotic device. Both the period of pronation and the amount of maximum pronation were significantly reduced by using the foot orthotic device. The data support the conclusion that foot orthotic devices can be successfully used to modify selected aspects of lower extremity mechanics during the support phase of running.

Barry T. Bates

Papers

Injuries to runners.

Contributions of lower extremity joints to energy dissipation during landings.

The evaluation and prediction of impact forces during landings

Biomechanical factors associated with injury during landing in jump sports.

Foot orthotic devices to modify selected aspects of lower extremity mechanics