What Risk Factors Are Associated With Musculoskeletal Injury in US Army Rangers? A Prospective Prognostic Study.

BACKGROUND: Musculoskeletal injury is the most common reason that soldiers are medically not ready to deploy. Understanding intrinsic risk factors that may place an elite soldier at risk of musculoskeletal injury may be beneficial in preventing musculoskeletal injury and maintaining operational military readiness. Findings from this population may also be useful as hypothesis-generating work for particular civilian settings such as law enforcement officers (SWAT teams), firefighters (smoke jumpers), or others in physically demanding professions. QUESTIONS/PURPOSES: The purposes of this study were (1) to examine whether using baseline measures of self-report and physical performance can identify musculoskeletal injury risk; and (2) to determine whether a combination of predictors would enhance the accuracy for determining future musculoskeletal injury risk in US Army Rangers. METHODS: Our study was a planned secondary analysis from a prospective cohort examining how baseline factors predict musculoskeletal injury. Baseline predictors associated with musculoskeletal injury were collected using surveys and physical performance measures. Survey data included demographic variables, injury history, and biopsychosocial questions. Physical performance measures included ankle dorsiflexion, Functional Movement Screen, lower and upper quarter Y-balance test, hop testing, pain provocation, and the Army Physical Fitness Test (consisting of a 2-mile run and 2 minutes of sit-ups and push-ups). A total of 320 Rangers were invited to enroll and 211 participated (66%). Occurrence of musculoskeletal injury was tracked for 1 year using monthly injury surveillance surveys, medical record reviews, and a query of the Department of Defense healthcare utilization database. Injury surveillance data were available on 100% of the subjects. Receiver operator characteristic curves and accuracy statistics were calculated to identify predictors of interest. A logistic regression equation was then calculated to find the most pertinent set of predictors. Of the 188 Rangers (age, 23.3 ± 3.7 years; body mass index, 26.0 ± 2.4 kg/m(2)) remaining in the cohort, 85 (45.2%) sustained a musculoskeletal injury of interest. RESULTS: Smoking, prior surgery, recurrent prior musculoskeletal injury, limited-duty days in the prior year for musculoskeletal injury, asymmetrical ankle dorsiflexion, pain with Functional Movement Screen clearing tests, and decreased performance on the 2-mile run and 2-minute sit-up test were associated with increased injury risk. Presenting with one or fewer predictors resulted in a sensitivity of 0.90 (95% confidence interval [CI], 0.83-0.95), and having three or more predictors resulted in a specificity of 0.98 (95% CI, 0.93-0.99). The combined factors that contribute to the final multivariable logistic regression equation yielded an odds ratio of 4.3 (95% CI, 2.0-9.2), relative risk of 1.9 (95% CI, 1.4-2.6), and an area under the curve of 0.64. CONCLUSIONS: Multiple factors (musculoskeletal injury history, smoking, pain provocation, movement tests, and lower scores on physical performance measures) were associated with individuals at risk for musculoskeletal injury. The summation of the number of risk factors produced a highly sensitive (one or less factor) and specific (three or more factors) model that could potentially be used to effectively identify and intervene in those persons with elevated risk for musculoskeletal injury. Future research should establish if screening and intervening can improve musculoskeletal health and if our findings among US Army Rangers translate to other occupations or athletes. LEVEL OF EVIDENCE: Level II, prognostic study.

Prediction of injury by limited and asymmetrical fundamental movement patterns in american football players.

CONTEXT: Previous injury is the strongest risk factor for future injury in sports. It has been proposed that motor-control changes such as movement limitation and asymmetry associated with injury and pain may be perpetuated as part of an individual's movement strategy. Motor control of fundamental 1-×-body-weight tasks can reliably and efficiently be measured in the field. OBJECTIVE: To determine whether the motor control of fundamental movement patterns and pattern asymmetry have a relationship with time-loss injury over the course of the preseason in professional football. DESIGN: Injury-risk study. SETTING: American professional football facilities. PARTICIPANTS: 238 American professional football players. INTERVENTION: To measure the motor control of 1-×-body-weight fundamental movement patterns, Functional Movement Screen scores were obtained before the start of training camp. The previously established cutoff score of ≤14 and the presence of any asymmetries on the FMS were examined using relative risk to determine if a relationship exists with time-loss injury. MAIN OUTCOME MEASURE: Time-loss musculoskeletal injury defined as any time loss from practice or competition due to musculoskeletal injury. RESULTS: Players who scored ≤14 exhibited a relative risk of 1.87 (CI95 1.202.96). Similarly, players with at least 1 asymmetry displayed a relative risk of 1.80 (CI95 1.112.74). The combination of scoring below the threshold and exhibiting a movement asymmetry was highly specific for injury, with a specificity of .87 (CI95 .84.90). CONCLUSION: The results of this study suggest that fundamental movement patterns and pattern asymmetry are identifiable risk factors for time-loss injury during the preseason in professional football players.

Upper Quarter Y Balance Test: reliability and performance comparison between genders in active adults.

The inclusion of movement tests before performance training and sport participation is gaining popularity as part of musculoskeletal screening for injury. The identification of an athlete's asymmetries and poor performance in the preseason allows coaches and sports medicine clinicians the opportunity to proactively address these deficits to reduce the potential for injury. Currently, there are no tests reported in the literature that simultaneously require shoulder and core stability while taking the subjects through a large range of motion at the end range of their stability. Thus, the purpose of this article was to describe the Upper Quarter Y Balance Test and report the gender differences in the performance of the test. Upper extremity reach distances were measured in 95 active adults using a standardized upper extremity balance-and-reach protocol. Intraclass correlation coefficients were used to assess reliability, and gender differences were analyzed using an independent samples t-test, whereas bilateral differences were analyzed using a dependent samples t-test for the normalized composite reach scores. Intraclass correlation coefficient (3.1) for test-retest reliability ranged from 0.80 to 0.99. Intraclass correlation coefficient (3.1) for interrater reliability was 1.00. Average composite scores (right/left) reported as a percentage of limb length were 81.7/82.3% for men and 80.7/80.7% for women. The results of the study suggest that the Upper Quarter Y Balance Test is a reliable test for measuring upper extremity reach distance while in a closed-chain position. It was further determined that there was no significant difference in performance between genders or between sides on the test when normalized to limb length. Coaches and sports medicine professionals may consider incorporating the Upper Quarter Y Balance Test as part of their preprogram testing to identify movement limitations and asymmetries in athletes and thereby may reduce injury.

Automation to improve efficiency of field expedient injury prediction screening.

Musculoskeletal injuries are a primary source of disability in the U.S. Military. Physical training and sports-related activities account for up to 90% of all injuries, and 80% of these injuries are considered overuse in nature. As a result, there is a need to develop an evidence-based musculoskeletal screen that can assist with injury prevention. The purpose of this study was to assess the capability of an automated system to improve the efficiency of field expedient tests that may help predict injury risk and provide corrective strategies for deficits identified. The field expedient tests include survey questions and measures of movement quality, balance, trunk stability, power, mobility, and foot structure and mobility. Data entry for these tests was automated using handheld computers, barcode scanning, and netbook computers. An automated algorithm for injury risk stratification and mitigation techniques was run on a server computer. Without automation support, subjects were assessed in 84.5 ± 9.1 minutes per subject compared with 66.8 ± 6.1 minutes per subject with automation and 47.1 ± 5.2 minutes per subject with automation and process improvement measures (p < 0.001). The average time to manually enter the data was 22.2 ± 7.4 minutes per subject. An additional 11.5 ± 2.5 minutes per subject was required to manually assign an intervention strategy. Automation of this injury prevention screening protocol using handheld devices and netbook computers allowed for real-time data entry and enhanced the efficiency of injury screening, risk stratification, and prescription of a risk mitigation strategy.

Interrater reliability of the functional movement screen.

The Functional Movement Screen (FMS) is a series of 7 tests that categorize fundamental movement. Each test is scored on an ordinal scale with 4 categories. The purpose of this study was to determine the interrater reliability of the FMS. Forty healthy subjects were videotaped while performing the FMS. The videos were independently scored by 4 raters, including 2 experts who instruct FMS training courses and 2 novices who completed a standardized training course on the FMS. Interrater reliability was analyzed using the weighted kappa statistic. The novice raters demonstrated excellent or substantial agreement on 14 of the 17 tests, whereas the expert raters did the same on 13 of the 17 tests. When the novice raters were paired with the expert raters, all 17 components demonstrated excellent or substantial agreement. These data indicate that the FMS can confidently be applied by trained individuals. This would suggest that the FMS can be confidently used to assess the movement patterns of athletes and to make decisions related to interventions for performance enhancement, and the FMS may assist in identifying athletes at risk for injury.

Biomechanical analysis of the different classifications of the Functional Movement Screen deep squat test.

The purpose of this study is to examine the peak sagittal plane joint angles and joint moments of the lower extremity during the deep squat (DS) movement of the Functional Movement Screen (FMS) to assess differences between the classifications (1,2,3). Twenty-eight participants volunteered for the study and were screened to assess their FMS score on the DS task. All participants underwent a quantitative movement analysis performing the FMS DS movement at a self-selected speed. The participants in Group 3 exhibited greater dorsiflexion excursion compared to those in Group 1. Participants in Group 3 had greater peak knee flexion and knee flexion excursion than those in Group 2 who exhibited more than the participants in Group 1. Group 3 also exhibited a greater peak knee extension moment compared to Group 1. At the hip, Groups 3 and 2 exhibited greater peak hip flexion, hip flexion excursion and peak hip extension moment compared to Group 1. Thus, it appears that individuals who score differently on the deep squat as determined by the FMS exhibit differences in mechanics that may be beneficial in assessing strategies for interventions. Future research should assess how fundamental changes in mobility and stability independently affect DS performance.

CAN INJURY RISK CATEGORY BE CHANGED IN ATHLETES? AN ANALYSIS OF AN INJURY PREVENTION SYSTEM.

BACKGROUND AND PURPOSE: Researchers have used an injury risk algorithm utilizing demographic data, injury history, the Functional Movement Screen™ (FMS™) and Lower Quarter Y Balance Test™ (YBT™) scores to categorize individual injury risk. The purpose of this study was to identify if a group-based hybrid injury prevention program utilizing key factors from previous research with the addition of an individualized approach can modify the injury risk category of athletes. STUDY DESIGN: Cohort Study. METHODS: Forty-four female subjects (ages 14-17) were recruited from a local high school soccer team. Pre-participation testing included demographic data, injury history, FMS™ and YBT™ to determine if each athletes' injury risk category using the Move2Perform algorithm. Post-testing took place after an eight-week exercise-based intervention program was completed. McNemar analysis was utilized to assess changes in the injury risk categories. RESULTS: A significant number of athletes (21 of 44) moved to lower risk categories at posttest (p=0.000; Z=-3.869). Of the 32 athletes in the High Risk category at pretest, 16 were Low Risk after the intervention (p=0.002). CONCLUSIONS: A preseason, group injury prevention training program with individually prescribed corrective exercises, resulted in a significant number of subjects decreasing their injury risk category. The primary statistically significant decrease of injury risk category was seen in the Moderate Risk individuals moving down to Slight. There were three athletes that moved from the Substantial Risk category to Slight, however, this change was not statistically significant. LEVEL OF EVIDENCE: 2.

THE EFFECT of ONE-ON-ONE INTERVENTION in ATHLETES with MULTIPLE RISK FACTORS for INJURY.

BACKGROUND: Lower extremity injuries in soccer players are extremely common. Implementation of group injury prevention programs has gained popularity due to time and cost-effectiveness. Unfortunately, players with greater number of risk factors are most likely to sustain an injury, yet less likely to benefit from a group injury prevention program. The purpose of this study was to determine if targeting these high risk players with one-on-one treatment would result in a reduction in the number of risk factors they possess. The authors hypothesized that fifty percent or more of subjects receiving one-on-one intervention would have a reduction of ≥1 risk factor(s). STUDY DESIGN: Quasi-experimental pretest-posttest design. METHODS: Division I men's and women's soccer players were screened for modifiable risk factors using a battery of tests which assessed mobility, fundamental movement pattern performance, motor control, and pain. Players with ≥ 3 risk factors ("high risk") received one-on-one treatment from a physical therapist via an algorithm twice per week for four weeks. Players with < 3 risk factors ("low risk") did not receive one-on-one intervention. RESULTS: The proportion of treatment successes in the intervention group was 0.923 (95% CI 0.640-0.998). A significant proportion of high risk subjects (0.846) became low risk at posttest (p = 0.003). A significant between group difference was noted in risk factor change from pretest to posttest (p = 0.002), with the median risk factor change in the intervention group being -3. CONCLUSION: Utilizing one-on-one interventions designed to target evidence-based risk factors is an effective strategy to eliminate LE musculoskeletal injury risk factors in high risk individuals. LEVELS OF EVIDENCE: 2b.

A comparison of select trunk muscle thickness change between subjects with low back pain classified in the treatment-based classification system and asymptomatic controls.

STUDY DESIGN: Cross-sectional descriptive. OBJECTIVES: To investigate if muscle thickness change, as measured with rehabilitative ultrasound imaging (RUSI), is different across subgroups of patients with low back pain (LBP), classified in the Treatment-Based Classification (TBC) system, when compared to controls. BACKGROUND: Researchers have demonstrated that subgroups of patients with LBP exist and respond differently to treatment, challenging the assertion that LBP is "nonspecific." The TBC system uses 4 categories (stabilization, mobilization, direction specific exercise, or traction) to subgroup patients. Recently, researchers have demonstrated impairments of the transverse abdominis (TrA) and lumbar multifidus (LM) in those with LBP, regardless of classification. Although distinct differences in impairments have been identified between subgroups, TrA and LM impairments have not been studied and may be present across categories of the TBC system. METHODS AND MEASURES: RUSI was utilized to measure percent thickness change from rest to contracted state during a voluntary task of the TrA and during an upper extremity task known to activate the LM in 56 subjects classified in the TBC system and 20 controls. RESULTS: During the prone upper extremity lifting task with a hand weight, there was a significant group difference for the LM at L4-L5 (P = .03) and at L5-S1 (P = .04), and during volitional activation for the TrA (P < .01). Post hoc testing revealed the differences were between controls and both the direction specific and stabilization categories at the L4-L5 level, between control and direction specific category for the L5-S1 level, and between controls and all 3 categories for the TrA. CONCLUSION: Deficits in the ability to generate muscle thickness changes in the TrA and LM occurred across categories of the TBC system. Intervention studies should be performed to determine if intervention can correct these deficits and if deficit corrections are related to outcomes.

Association of Physical Inactivity, Weight, Smoking, and Prior Injury on Physical Performance in a Military Setting.

CONTEXT: Although inactivity, being overweight, smoking, and a history of injury are identified as risk factors for poor health and injury, few authors have examined their association on physical performance. Young adults may be more likely to adopt healthier lifestyles if they understand the effect of health behaviors on performance. OBJECTIVE: To determine the association of being overweight, smoking, inactivity, and a history of injury with physical performance. DESIGN: Cross-sectional study. SETTING: Military population. PATIENTS OR OTHER PARTICIPANTS: Active-duty service members (N = 1466; 1380 men, 86 women; age = 24.7 ± 5.0 years; body mass index = 26.7 ± 3.4 kg/m2). MAIN OUTCOME MEASURE(S): Participants performed 8 measures (the triple-crossover hop for distance, the 6-m timed-hop test, the Functional Movement Screen, the Lower Quarter Y-Balance Test, the Upper Quarter Y-Balance Test, and the 3-event Army Physical Fitness Test) for evaluation of endurance, strength, muscular endurance, power, agility, balance, and motor control. Participants were categorized based on the number of health risk factors present. Using an analysis of covariance, we assessed the relationship between risk factors and physical performance with age and sex as covariates. RESULTS: Compared with those who had no risk factors (27.9% of men, 34.9% of women), physical performance was worse in those who had 1, 2, or 3 to 4 risk factors present by 4.3%, 6.7%, and 10.3%, respectively. Decrements in performance for those with 3 to 4 risk factors ranged from 3.3% to 14.4%. CONCLUSIONS: An unhealthy lifestyle habit or a history of injury was negatively associated with physical performance. Physical performance decrements were associated with the number of risk factors present. Understanding how risk factors contribute to decreased physical performance may enable clinicians to improve compliance with injury-prevention programs in occupational settings in which a young and relatively healthy workforce may be more concerned about performance than health.

Application of Athletic Movement Tests that Predict Injury Risk in a Military Population: Development of Normative Data.

Performance on movement tests helps to predict injury risk in a variety of physically active populations. Understanding baseline measures for normal is an important first step. OBJECTIVES: Determine differences in physical performance assessments and describe normative values for these tests based on military unit type. METHODS: Assessment of power, balance, mobility, motor control, and performance on the Army Physical Fitness Test were assessed in a cohort of 1,466 soldiers. Analysis of variance was performed to compare the results based on military unit type (Rangers, Combat, Combat Service, and Combat Service Support) and analysis of covariance was performed to determine the influence of age and gender. RESULTS: Rangers performed the best on all performance and fitness measures (p < 0.05). Combat soldiers performed better than Combat Service and Service Support soldiers on several physical performance tests and the Army Physical Fitness Test (p < 0.05). Performance in Combat Service and Service Support soldiers was equivalent on most measures (p < 0.05). CONCLUSIONS: Functional performance and level of fitness varied significantly by military unit type. Understanding these differences will provide a foundation for future injury prediction and prevention strategies.

Normative data and the influence of age and gender on power, balance, flexibility, and functional movement in healthy service members.

OBJECTIVES: Determine the influence of age and sex and describe normative data on field expedient tests associated with power, balance, trunk stability, mobility, and functional movement in a military population. METHODS: Participants (n = 247) completed a series of clinical and functional tests, including closed-chain ankle dorsiflexion (DF), Functional Movement Screen (FMS), Y-Balance Test Lower Quarter (YBT-LQ), Y-Balance Test Upper Quarter (YBT-UQ), single leg vertical jump (SLVJ), 6-m timed hop (6-m timed), and triple hop. Descriptive statistics were calculated. Analysis of variance tests were performed to compare the results based on sex and age (<30 years, >30 years). RESULTS: Service members demonstrated DF of 34.2 ± 6.1°, FMS composite score of 16.2 ± 2.2, YBT-LQ normalized composite score of 96.9 ± 8.6%, YBT-UQ normalized composite score of 87.6 ± 9.6%, SLVJ of 26.9 ± 8.6 cm, 6-m hop of 2.4 ± 0.5 seconds, and a triple hop of 390.9 ± 110.8 cm. Men performed greater than women (p < 0.05) on the YBT-LQ, YBT-UQ, SLVJ, 6-m timed, and triple hop. Those <30 years of age performed better than older participants (p < 0.05) on the DF, FMS, YBT-LQ, SLVJ, 6-m hop, and triple hop. CONCLUSIONS: Findings provide normative data on military members. Men performed better on power, balance, and trunk stability tests, whereas younger individuals performed better on power, balance, mobility, and functional movement.

Bilateral differences in the upper quarter function of high school aged baseball and softball players.

PURPOSE/BACKGROUND: The Upper Quarter Y Balance Test (YBT-UQ) was developed as a way to identify upper extremity and trunk mobility in the open kinetic chain in the reaching limb as well as midrange limitations and asymmetries of upper extremity and core stability in the closed kinetic chain on the stabilizing limb. Performance on the YBT-UQ is similar between genders and between limbs; however, this has not been examined in athletes who participate in sports that result in upper extremity asymmetries. The primary purpose of this study is to determine if differences exist between the throwing vs. non-throwing sides in high-school baseball and softball athletes on the YBT-UQ. METHODS: In order to complete this forty-eight male high school baseball players and seventeen female high school softball players were tested on the YBT-UQ. Reach distances were normalized to arm length (% AL). Comparisons were made between the throwing (T) and non-throwing (NT) arm for each direction as well as the composite score. RESULTS: No significant differences were observed between the T and NT arm for the medial (NT: 98.4 ± 8.6 %AL, T: 99.1 ± 8.6 %AL, p=0.42), inferolateral (NT: 90.8 ± 11.8 %AL, T: 90.3 ± 11.5 %AL, p =0.61), superolateral (NT: 70.6 ± 10.9 %AL, T: 70.4 ± 11.1 % AL, p=0.91) reaches, or the composite score (NT: 87.2 ± 8.9 % AL, T: 86.6 ± 8.1 %AL, p=0.72). Similarly, no differences were observed between the male baseball and female softball players (p=0.30-0.90). CONCLUSIONS: Based on these findings, it was concluded that there was no difference in performance on the YBT-UQ between throwing and non-throwing limbs in high school baseball and softball players. LEVEL OF EVIDENCE: 3.

Comparison of dynamic balance in adolescent male soccer players from rwanda and the United States.

PURPOSE/BACKGROUND: Dynamic balance is an important component of motor skill development. Poor dynamic balance has previously been associated with sport related injury. However, the vast majority of dynamic balance studies as they relate to sport injury have occurred in developed North American or European countries. Thus, the purpose of this study was to compare dynamic balance in adolescent male soccer players from Rwanda to a matched group from the United States. METHODS: Twenty-six adolescent male soccer players from Rwanda and 26 age- and gender-matched control subjects from the United States were screened using the Lower Quarter Y Balance Test during their pre-participation physical. Reach asymmetry (cm) between limbs was examined for all reach directions. In addition, reach distance in each direction (normalized to limb length, %LL) and the composite reach score (also normalized to %LL) were examined. Dependent samples t-tests were performed with significant differences identified at p<0.05. RESULTS: Twenty-six male soccer players from Rwanda (R) were matched to twenty-six male soccer players from the United States (US). The Rwandan soccer players performed better in the anterior (R: 83.9 ± 3.2 %LL; US: 76.5 ± 6.6 %LL, p<0.01), posterolateral (R: 114.4 ± 8.3 %LL ; US: 106.5 ± 8.2 %LL, p<0.01) and composite (R: 105.6 ± 1.3 %LL; US: 97.8 ± 6.2 %LL, p<0.01) reach scores. No significant differences between groups were observed for reach asymmetry. CONCLUSIONS: Adolescent soccer players from Rwanda exhibit superior performance on a standardized dynamic balance test as comparison to similar athletes from the United States. The examination of movement abilities of athletes from countries of various origins may allow for a greater understanding of the range of true normative values for dynamic balance. LEVELS OF EVIDENCE: 3b.

Dynamic balance performance and noncontact lower extremity injury in college football players: an initial study.

BACKGROUND: Field expedient screening tools that can identify individuals at an elevated risk for injury are needed to minimize time loss in American football players. Previous research has suggested that poor dynamic balance may be associated with an elevated risk for injury in athletes; however, this has yet to be examined in college football players. HYPOTHESIS: To determine if dynamic balance deficits are associated with an elevated risk of injury in collegiate football players. It was hypothesized that football players with lower performance and increased asymmetry in dynamic balance would be at an elevated risk for sustaining a noncontact lower extremity injury. STUDY DESIGN: Prospective cohort study. METHODS: Fifty-nine collegiate American football players volunteered for this study. Demographic information, injury history, and dynamic balance testing performance were collected, and noncontact lower extremity injuries were recorded over the course of the season. Receiver operator characteristic curves were calculated based on performance on the Star Excursion Balance Test (SEBT), including composite score and asymmetry, to determine the population-specific risk cut-off point. Relative risk was then calculated based on these variables, as well as previous injury. RESULTS: A cut-off point of 89.6% composite score on the SEBT optimized the sensitivity (100%) and specificity (71.7%). A college football player who scored below 89.6% was 3.5 times more likely to get injured. CONCLUSION: Poor performance on the SEBT may be related to an increased risk for sustaining a noncontact lower extremity injury over the course of a competitive American football season. CLINICAL RELEVANCE: College football players should be screened preseason using the SEBT to identify those at an elevated risk for injury based upon dynamic balance performance to implement injury mitigation strategies to this specific subgroup of athletes.

Differences in soccer players' dynamic balance across levels of competition.

CONTEXT: Balance ability has been associated with performance and injury prevention in athletes. Few published reports have investigated the differences in dynamic balance abilities among male high school, collegiate, and professional soccer players. OBJECTIVE: To examine the differences on the Lower Quarter Y-Balance Test in male high school, collegiate, and professional soccer players. DESIGN: Descriptive laboratory study. SETTING: Field testing. Patients or Other Participants: Dynamic balance data were collected for male high school (HS; n = 38), collegiate (n = 37), and professional (n = 44) soccer players during preparticipation physical examinations using the Lower Quarter Y Balance Test standardized protocol. Main Outcome Measure(s): For the Lower Quarter Y Balance Test, the participant reaches with 1 foot in the anterior, posteromedial, and posterolateral directions while standing on a centralized stance platform with the other foot. The test is performed for both left and right limbs. Differences in reach distances between competition levels were analyzed using a 1-way analysis of variance with significance set at P < .05. The HS group had a greater anterior reach distance than the other 2 groups. In contrast, the HS group had less reach distance in the posteromedial and posterolateral directions than the other groups. Also, HS players tended to exhibit a lower composite reach score than the other groups, but this difference was not significant (P = .08). No differences were observed among groups for bilateral symmetry in any of the reach directions. CONCLUSIONS: Dynamic balance performance varied with competition level. This may indicate that athletes' movement strategies may be different depending on the competition level and that normative values may need to be established for each competition level.

Experimentally induced pain alters the EMG activity of the lumbar multifidus in asymptomatic subjects.

Lumbar musculature plays an important role in stabilization during functional movements such as walking, bending and overhead activities. Current research has focused on the lumbar multifidus (LM) muscle to determine if altered activity of the LM may contribute to low back pain (LBP). Therefore, the purpose of this study was to determine whether experimentally induced LBP affects deep LM muscle activity during functionally oriented tasks, weight shifting and upper extremity lifting. Intramuscular electromyography (EMG) activity of the LM at L4 was measured in 17 healthy adults during a dominant side shoulder flexion and extension task and during a staggered-stance weight shift task. Data were collected at baseline, after pain was induced with hypertonic saline and after the pain had subsided. Comparisons of within-subjects effects were performed with the use of a two-way repeated-measure ANOVA. A significantly higher magnitude of activity was found in the induced pain condition as compared to the baseline condition for the shoulder extension phase of the upper extremity task (p = 0.04). During forward weight shifting, lower values in both the induced pain (p = 0.02) and the recovery conditions (p = 0.01) were measured. During backward weight shifting, lower values were measured during the recovery condition as compared to baseline (p = 0.03). Across trials and subjects the EMG amplitudes were increased during the extension phase of the upper extremity task and decreased during the weight shifting task. These results suggest that the LM does not respond to induced pain in the same manner during different phases of functionally oriented tasks.

The reliability of an instrumented device for measuring components of the star excursion balance test.

BACKGROUND: The Star Excursion Balance Test (SEBT) is a dynamic test that requires strength, flexibility, and proprioception and has been used to assess physical performance, identify chronic ankle instability, and identify athletes at greater risk for lower extremity injury. In order to improve the repeatability in measuring components of the SEBT, the Y Balance Test™ has been developed. OBJECTIVE: The purpose of this paper is to report the development and reliability of the Y Balance Test™. METHODS: Single limb stance excursion distances were measured using the Y Balance Test™ on a sample of 15 male collegiate soccer players. Intraclass Correlation Coefficients (ICC) were used to determine the reliability of the test. RESULTS: The ICC for intrarater reliability ranged from 0.85 to 0.91 and for interrater reliability ranged from 0.99 to 1.00. Composite reach score reliability was 0.91 for intrarater and 0.99 for interrater reliability. DISCUSSION: This study demonstrated that the Y Balance Test™ has good to excellent intrarater and interrater reliability. The device and protocol attempted to address the common sources of error and method variation in the SEBT including whether touch down is allowed with the reach foot, where the stance foot is aligned, movement allowed of the stance foot, instantaneous measurement of furthest reach distance, standard reach height from the ground, standard testing order, and well defined pass/fail criteria. CONCLUSION: The Y Balance Test™ is a reliable test for measuring single limb stance excursion distances while performing dynamic balance testing in collegiate soccer players.

Rehabilitative ultrasound measurement of select trunk muscle activation during induced pain.

Rehabilitative ultrasound imaging (RUSI) is considered a valid method to measure muscle activation in key spinal muscles in asymptomatic subjects. Research measuring muscle activation with RUSI in painful subjects is limited. The aim of this study was to determine if changes in muscle activation from experimentally induced pain can be measured by RUSI. Six male subjects performed tasks known to activate the transverse abdominis (TrA) and lumbar multifidus (LM) while RUSI measurements of muscle thickness were obtained during control and hypertonic saline conditions. The abdominal draw-in maneuver was used to volitionally activate the TrA and a series of upper extremity lifting tasks were used to automatically activate the LM. Pain was induced by injecting 5% hypertonic saline into the longissimus muscle adjacent to the LM at the L4 level. The percent change in muscle thickness from rest to contraction represented muscle activation. Activation was significantly less (p<0.01) during the painful condition on 4 of the 5 tasks performed for the LM and on the task performed for the TrA. These results indicate that RUSI can be used to measure pain-related changes in deep trunk muscle activation. Future research should include a larger sample size and women.

Measurement of lumbar multifidus muscle contraction with rehabilitative ultrasound imaging.

Rehabilitative Ultrasound Imaging (RUSI) has been validated as a noninvasive method to measure activation of selected muscles. The purpose of this study was to determine the relationship between muscle thickness change, as measured by ultrasonography, and electromyography (EMG) activity of the lumbar multifidus (LM) muscle in normal subjects. Bipolar fine wire electrodes were inserted into the LM at the L4 level of five subjects. Simultaneous EMG and RUSI data (muscle thickness) were collected while subjects performed increasingly demanding postural response tasks thought to activate the LM muscle. To determine the relationship between muscle thickness change and EMG activity, the normalized EMG data were correlated to normalized RUSI data. To determine if the tasks increased the demand on the LM, the mean EMG data were compared over each of the four tasks. Muscle thickness change as measured by RUSI was highly correlated with EMG activity of LM in asymptomatic subjects (r=.79,P<.001). Mean EMG data showed increasing levels of activation across tasks (19-34% of maximum voluntary isometric contraction (MVIC)). The results of the repeated measures ANOVA demonstrated theses differences were significant (F(3,12)=25.39,P<.001). Measurement of muscle thickness change utilizing RUSI is a valid and potentially useful method to measure activation of the LM muscle in a narrow range (19-34% of MVIC) in an asymptomatic population.