Shoulder Flexion Torque Is Augmented by a Volitional Abdominal Isometric Contraction.

ABSTRACT: Cacolice, PA, Carcia, CR, and Scibek, JS. Shoulder flexion torque is augmented by a volitional abdominal isometric contraction. J Strength Cond Res 35(4): 920-923, 2021-A stable core provides a solid base to facilitate effective extremity function. It is unclear whether an individual is able to produce a greater amount of upper extremity torque while performing a volitional core contraction when compared with the independent contraction that occurs subconsciously. Therefore, the purpose of this study was to determine whether peak shoulder flexion torque values were different with and without a concurrent volitional core isometric contraction. Thirty healthy, recreationally active college-aged students participated. Surface electromyography from the rectus abdominis (RA) was captured using a telemetry system interfaced with a software acquisition system and personal computer. In a counterbalanced alternating order, subjects completed 3 trials of maximal isometric shoulder flexion at 90° with and without a volitional abdominal contraction. Percent activation of the RA was greater when subjects volitionally contracted their core (15.8 ± 12.7%) compared with the subconscious contracted condition (6.3 ± 4.8%) (p ≤ 0.001). Isometric shoulder flexion peak torque was greater when the core was actively contracted (44.6 ± 18.9 N × m) compared with when the core was recruited subconsciously (30.7 ± 15.7 N × m) (p ≤ 0.001). These findings suggest the clinician should encourage the individual to activate their core musculature when performing upper extremity strength activities.

The effect of Astym® Therapy on muscle strength: a blinded, randomized, clinically controlled trial.

BACKGROUND: Astym(®) therapy is a manual therapy intervention used to stimulate tissue healing, decrease pain, improve mobility, and improve muscle performance associated with musculoskeletal pathology. The purpose of this study was to determine if Astym therapy administered to the lower extremity would result in an immediate change of maximal force output during a unilateral isometric squat test among individuals with a lower extremity injury. METHODS: Forty-five subjects (14 males; 31 females) between 18 and 65 years of age were randomized into 3 treatment groups: 1) Control group - received no treatment 2) Placebo group - received a sham Astym treatment 3) Astym therapy group- received Astym therapy to the lower extremity. A baseline measure of maximal force output (pre-test) during a unilateral isometric squat was performed. The subjects then received the designated treatment intervention. Immediately following the treatment intervention, maximal force output (post-test) was retested using identical testing procedures by an investigator who was blinded to the treatment intervention received by the subjects. The percent change of maximal force output from pre-test to post-test measures was compared using a one-way analysis of variance. A Tukey's post-hoc analysis determined the statistical differences between the groups. RESULTS: The treatment intervention had a significant effect on the percent change of maximal force output [F(2,42) = 7.91, p = 0.001]. Tukey's post hoc analysis demonstrated that the percent change of maximal force output was significantly greater in the Astym group (15 ± 18 % change of Newtons) compared to the placebo (-6 ± 11 % change of Newtons; p = 0.0001) and control (-1 ± 17 % change of Newtons; p = 0.0014) groups. No significant difference (p = 0.68) was noted between the control and placebo groups. CONCLUSIONS: Astym therapy to the involved lower extremity increased maximum force output during an isometric squat test immediately following treatment. The results of this study suggest that Astym therapy can immediately improve muscle performance (maximal force output) for patients presenting with muscular weakness caused by a lower extremity musculoskeletal injury. TRIAL REGISTRATION: Clinicaltrials.gov NCT02349230. Registered 23 January 2015.

Causation and management of calcific tendonitis and periarthritis.

PURPOSE OF REVIEW: The purpose of this review is to update the reader on contemporary theory related to the cause of calcific periarthritis and provide the latest evidence associated with treating recalcitrant cases. RECENT FINDINGS: Contemporary theory suggests calcific periarthritis is the result of a cellular-mediated process in which calcium is deposited and resorbed via a multiple phase process. Resorption is associated with an acute inflammatory response and is often the factor that prompts one to seek medical care. The majority of cases require nothing more than a combination of symptomatic care and benign neglect. A small percentage of cases require intervention to further stimulate deposit resorption. Moderate evidence exists for extracorporeal shock wave therapy in the treatment of chronic cases related to deposits about the shoulder. Numerous case studies support the use of NSAIDs as an effective intervention for retropharyngeal periarthritis. If conservative interventions fail, surgery appears to be a viable option for symptom relief associated with rotator cuff calcific deposits. SUMMARY: Periarthritis is typically a symptom-limiting condition that resolves spontaneously. Numerous conservative treatment modalities each with varying levels of evidence exist for use in refractory cases. Future study is necessary to further refine the efficacy and parameters associated with available interventions.

Validation and repeatability of a shoulder biomechanics data collection methodology and instrumentation.

The purpose of our study was to establish criterion-related validity and repeatability of a shoulder biomechanics testing protocol involving an electromagnetic tracking system (Flock of Birds [FoB]). Eleven subjects completed humeral elevation tasks in the sagittal, scapular, and frontal planes on two occasions. Shoulder kinematics were assessed with a digital inclinometer and the FoB. Intrasession and intersession repeatability for orthopedic angles, and humeral and scapular kinematics ranged from moderate to excellent. Correlation analyses revealed strong relationships between inclinometer and FoB measures of humeral motion, yet considerable mean differences were noted between the measurement devices. Our results validate use of the FoB for measuring humeral kinematics and establish our testing protocol as reliable. We must continue to consider factors that can impact system accuracy and the effects they may have on kinematic descriptions and how data are reported.

Presentation and conservative management of acute calcific tendinopathy: a case study and literature review.

BACKGROUND: The efficacy of a variety of noninvasive, conservative management techniques for calcific tendinopathy has been investigated and established for improving pain and function and/or facilitating a decrease in the size or presence of calcium deposits. Surprisingly, few have reported on the use of traditional therapeutic exercise and rehabilitation alone in the management of this condition, given the often spontaneous resorptive nature of calcium deposits. The purpose of this case is to present the results of a conservative approach, including therapeutic exercise, for the management of calcific tendinopathy of the supraspinatus, with an emphasis on patient outcomes. CASE DESCRIPTION: The patient was a self-referred 41-y-old man with complaints of acute right-shoulder pain and difficulty sleeping. Imaging studies revealed liquefied calcium deposits in the right supraspinatus. The patient reported constant pain at rest (9/10) and tenderness in the area of the greater tuberosity. He exhibited a decrease in all shoulder motions and had reduced strength. The simple shoulder test (SST) revealed limited function (0/12). Conservative management included superficial modalities and medication for pain and a regimen of scapulothoracic and glenohumeral range-of-motion (ROM) and strengthening exercises. OUTCOMES: At discharge, pain levels decreased to 0/10 and SST scores increased to 12/12. ROM was full in all planes, and resisted motion was strong and pain free. The patient was able to engage in endurance activities and continue practicing as a health care provider. DISCUSSION: The outcomes with respect to pain, function, and patient satisfaction provide evidence to support the use of conservative therapeutic interventions when managing patients with acute cases of calcific tendinopathy. Successful management of calcific tendinopathy requires attention to outcomes and an understanding of the pathophysiology, prognostic factors, and physical interventions based on the current stage of the calcium deposits and the patient's status in the healing continuum.

Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3 Student-Athletes.

Background/Purpose: Recent work has identified non-significant correlations of established limb dominance to the lower extremity (LE) at greater risk for Anterior Cruciate Ligament (ACL) injury in an active, non-athletic sample. The most common LE dominance definition is preferred leg to kick a ball. Athletes develop a unilaterality pattern different from their active, non-athlete peers. Therefore, the purpose of this study was to explore the correlation between the LE used to kick a ball with and the limb identified at greater risk of ACL injury in National Collegiate Athletic Association (NCAA) Division III athletes. Design: An Observational Descriptive study design. Methods: Forty-six student-athletes that were active on their NCAA Division III football, field hockey, volleyball, and soccer team rosters were recruited. Upon completing consent, participants performed two tasks (kicking a ball; unilateral land) in a counterbalanced order. Data were entered into and analyzed with a commercial statistical software package where a phi coefficient and Chi-squared analysis were performed. Results: Of the 46 student athletes who participated (Female=32, Male=14, 19.48±1.26years, 171.75±10.47cm, 77.26±18.74kg), 25 participants kicked and landed with the same limb. Twenty participants chose kicking and landing with different limbs. The Phi Coefficient (Φ= 0.001; P= 0.97) indicated little to no relationship between the LE a participant kicked and landed with. Likewise, the Chi-square statistic revealed no statistical differences between observed and expected frequencies (χ2= 0.001; p= 0.97). Discussion/Conclusion: NCAA Division III athletes display a statistical absence of preferred limb predictability utilizing the most common dominance definition (kicking a ball) as it relates to identifying LE at risk of ACL injury. The results suggest that the prevalent LE dominance definition is problematic when exploring ACL injury risk in this population.

Junior and Collegiate Tennis Players Display Similar Bilateral Asymmetries of Humeral Retroversion.

CONTEXT: Overhead throwing athletes consistently display significant bilateral differences in humeral retroversion (HRV). However, there is limited evidence regarding HRV asymmetries in tennis players despite similarities between the overhead throw and tennis serve. OBJECTIVE: To determine if junior and collegiate tennis players demonstrate bilateral differences in HRV, and whether the magnitude of the side-to-side difference (HRVΔ) was similar across different age groups. DESIGN: Cross-Sectional Study Setting: Field-Based Patients or Other Participants: Thirty-nine healthy tennis players were stratified into three age groups: Younger Juniors (n = 11; age = 14.5 ± 0.5 years), Older Juniors (n = 12; age = 17.1 ± 0.9 years), and Collegiate (n = 16; age = 19.6 ± 1.2 years). MAIN OUTCOME MEASURES: Three-trial means were calculated for HRV for the dominant and nondominant limbs, and HRVΔ was calculated by subtracting the mean of the nondominant side from the dominant side. Paired-sample t-tests were utilized to determine bilateral differences in HRV, while a one-way ANOVA was used to compare HRVΔ between groups. RESULTS: For all three groups, HRV was significantly greater in the dominant arm compared to the nondominant arm (Younger Juniors: dominant = 62.8° ± 9.1° vs nondominant = 56.3° ± 6.8°, P = .039; Older Juniors: dominant = 75.5° ± 11.2° vs nondominant = 68.6° ± 14.2°, P = .043; Collegiate: dominant = 71.7° ± 8.5° vs nondominant = 61.2° ± 6.9°, P = .001). However, no significant differences were detected in HRVΔ when compared across age groups (P = .511). CONCLUSIONS: Consistent with studies involving overhead throwing athletes, tennis players demonstrated significantly greater measures of HRV in the dominant limb. Further, the development of HRV asymmetries appear to have occurred prior to the teenage years as no changes were observed in HRVΔ between age groups.

The Single Leg Squat Test: A "Top-Down" or "Bottom-Up" Functional Performance Test?

BACKGROUND: Medial knee deviation (MKD) during the single leg squat test (SLST) is a common clinical finding that is often attributed to impairments of proximal muscular structures. Investigations into the relationship between MKD and the foot and ankle complex have provided conflicting results, which may impact clinicians' interpretation of the SLST. PURPOSE: The purpose of this study was to compare ankle dorsiflexion range of motion (ROM) and foot posture in subjects that perform the SLST with MKD (fail) versus without MKD (pass). HYPOTHESIS: There will be a difference in ankle dorsiflexion ROM and/or foot posture between healthy individuals that pass and fail the SLST for MKD. STUDY DESIGN: Cross-sectional study. METHODS: Sixty-five healthy, active volunteers (sex = 50 female, 15 male; age = 25.2 +/- 5.6 years; height = 1.7 +/- .1 m; weight = 68.5 +/- 13.5 kg) who demonstrated static balance and hip abductor strength sufficient for performance of the SLST participated in the study. Subjects were divided into pass and fail groups based on visual observation of MKD during the SLST. Foot Posture Index (FPI-6) scores and measures of non-weight bearing and weight bearing active ankle dorsiflexion (ROM) were compared. RESULTS: There were 33 individuals in the pass group and 32 in the fail group. The groups were similar on age (p = .899), sex (p = .341), BMI (p = .818), and Tegner Activity Scale score (p = .456). There were no statistically significant differences between the groups on the FPI-6 (pass group mean = 2.5 +/- 3.9; fail group mean = 2.3 +/- 3.5; p = .599), or any of the measures of dorsiflexion range of motion (non-weight bearing dorsiflexion with knee extended: pass group = 6.9o +/- 3.7o, fail group = 7.8o +/- 3.0o; non-weight bearing dorsiflexion with knee flexed: pass group = 13.5o +/- 5.6o, fail group = 13.9o +/- 5.3o; weight bearing dorsiflexion: pass group = 42.7o +/- 6.0o, 42.7o +/- 8.3o, p = .611). CONCLUSIONS: Failure on the SLST is not related to differences in clinical measures of active dorsiflexion ROM or foot posture in young, healthy individuals. These findings suggest that clinicians may continue using the SLST to assess neuromuscular performance of the trunk, hip, and knee without ankle dorsiflexion ROM or foot posture contributing to results. LEVEL OF EVIDENCE: Level 3.

Ankle Stability and Movement Coordination Impairments: Lateral Ankle Ligament Sprains Revision 2021.

This revised clinical practice guideline (CPG) addresses the distinct but related lower extremity impairments of those with a first-time lateral ankle sprain (LAS) and those with chronic ankle instability (CAI). Depending on many factors, impairments may continue following injury. While most individuals experience resolution of symptoms, complaints of instability may continue and are defined as CAI. The aims of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. J Orthop Sports Phys Ther 2021;51(4):CPG1-CPG80. doi:10.2519/jospt.2021.0302.

Ground Reaction Forces Are Predicted with Functional and Clinical Tests in Healthy Collegiate Students.

Increased vertical and posterior ground reaction forces (GRFs) are associated with anterior cruciate ligament (ACL) injury. If a practical means to predict these forces existed, ACL injury risk could be attenuated. Forty-two active college-age individuals (21 females, 20.66 ± 1.46 y, 70.70 ± 2.36 cm, 82.20 ± 7.60 kg; 21 males, 21.57 ± 1.28 y, 65.52 ± 1.87 cm, 64.19 ± 9.05 kg) participated in this controlled laboratory study. GRFs were ascertained by having the subjects perform a unilateral landing task onto a force plate. Several clinical measures (Fat Free Mass (FFM), dorsiflexion passive range of motion (DPROM), isometric peak force of the lateral hip rotators, knee flexor/extensor peak force ratio (H:Q), the completion of the overhead deep squat), two functional tests (Margaria-Kalamen, Single Leg Triple Hop (SLTH)), and sex served as the predictor variables. Regression models to predict the GRFs normalized to the FFM (nGRFz, nGRFy) were generated. nGRFz was best predicted with a linear regression equation that included SLTH and DPROM (adjusted R2 = 0.274; p = 0.001). nGRFy was best predicted with a linear regression equation that included H:Q, FFM, and DPROM (adjusted R2 = 0.476; p < 0.001). Simple clinical measures and functional tests explain a small to moderate amount of the variance associated with the FFM normalized vertical and posterior GRFs in active college-age individuals.

DEFINING LOWER EXTREMITY DOMINANCE: THE RELATIONSHIP BETWEEN PREFERRED LOWER EXTREMITY AND TWO FUNCTIONAL TASKS.

BACKGROUND: A commonly utilized operational definition of lower extremity (LE) dominance assumes the LE with which a participant prefers to kick a ball with is the same preferred LE a participant would choose for a unilateral landing task. HYPOTHESIS/PURPOSE: The purpose of this study was to determine the relationship between the preferred lower extremity (LE) when performing a unilateral landing and kicking task. The authors hypothesized a strong correlation between the LE the participant chose for the landing task and the LE the participant chose for the kicking task would be evident. STUDY DESIGN: Repeated measures. METHODS: A convenience sample of 50 (age = 21.9 ± 0.9 years; sex = 27 female; 23 male; height = 170.6 ± 10.8 cm; weight = 73.3 ± 18.3 kg) healthy, recreationally active college aged students performed two tasks (kicking a ball; unilateral drop jump landing) in a counterbalanced order. RESULTS: Thirty-three participants kicked and landed with their right LE; 14 kicked with the right and landed on their left; two kicked and landed with their left and one participant kicked with their left and landed on their right LE. The Phi Coefficient (ϕ = 0.18; p = 0.18) indicated little to no relationship between the preferred LE for kicking a ball and landing from a drop jump. Similarly, the Chi-squared statistic revealed no differences between observed and expected frequencies (χ2 = 1.76; p = 0.23). DISCUSSION: When studying anterior cruciate ligament injury mechanisms in the laboratory, most investigators examine characteristics of the dominant LE. Dominance is frequently defined by which LE the individual kicks a ball with. The majority of ACL injuries however occur to the landing or plant LE. Hence, LE limb selection based on this approach may be flawed. CONCLUSION: A significant relationship was not evident between the preferred LE for kicking a ball and a unilateral landing in a group of healthy recreationally active college aged students. The data suggests the preferred LE for kicking a ball and a unilateral landing task is not necessarily the same. LEVEL OF EVIDENCE: Level 3.

Reliability and Validity of a 1-Person Technique to Measure Humeral Torsion Using Ultrasound.

CONTEXT: Knowledge of the bilateral difference in humeral torsion (HT) enables clinicians to implement appropriate interventions for soft tissue restrictions of the shoulder to restore rotational motion and reduce injury risk. Whereas the current ultrasound method for measuring HT requires 2 assessors, a more efficient 1-person technique (1PT) may be of value. OBJECTIVE: To determine if a 1PT is a reliable and valid alternative to the established 2-person technique (2PT) for indirectly measuring HT using ultrasound. DESIGN: Descriptive laboratory study. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: A convenience sample of 16 volunteers (7 men, 9 women; age = 26.9 ± 6.8 years, height = 172.2 ± 10.7 cm, mass = 80.0 ± 13.3 kg). MAIN OUTCOME MEASURE(S): We collected the HT data using both the 1PT and 2PT from a total of 30 upper extremities (16 left, 14 right). Within-session intrarater reliability (intraclass correlation coefficient; ICC [3,1]) and standard error of measurement (SEM) were assessed for both techniques. Simple linear regression and Bland-Altman analysis were used to examine the validity of the 1PT when compared with the established 2PT. RESULTS: The 1PT (ICC [3,1] = 0.992, SEM = 0.8°) and 2PT (ICC [3,1] = 0.979, SEM = 1.1°) demonstrated excellent within-session intrarater reliability. A strong linear relationship was demonstrated between the HT measurements collected with both techniques ( r = 0.963, r2 = 0.928, F1,28 = 361.753, P < .001). A bias of -1.2° ± 2.6° was revealed, and the 95% limits of agreement indicated the 2 techniques can be expected to vary from -6.3° to 3.8°. CONCLUSIONS: The 1PT for measuring HT using ultrasound was a reliable and valid alternative to the 2PT. By reducing the number of testers involved, the 1PT may provide clinicians with a more efficient and practical means of obtaining these valuable clinical data. a.

Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision 2018.

The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). The purpose of these revised clinical practice guidelines is to review recent peer-reviewed literature and make recommendations related to midportion Achilles tendinopathy. J Orthop Sports Phys Ther 2018;48(5):A1-A38. doi:10.2519/jospt.2018.0302.

STRENGTH PROFILES IN HEALTHY INDIVIDUALS WITH AND WITHOUT SCAPULAR DYSKINESIS.

BACKGROUND: Muscular weakness of the shoulder complex is commonly found in patients presenting with scapular dyskinesis; however, little is known regarding muscular performance in healthy individuals with scapular dyskinesis. PURPOSE: To compare isometric strength measures of the shoulder complex between healthy individuals with and without scapular dyskinesis. It was hypothesized that healthy individuals with scapular dyskinesis would demonstrate decreased isometric strength of the scapular stabilizers and rotator cuff when compared to healthy individuals without scapular dyskinesis. STUDY DESIGN: Cross-sectional study. METHODS: Forty healthy, college-aged participants were recruited. Sixty-eight percent of subjects (27 of 40) presented with scapular dyskinesis. Thus, a matched-pairs analysis was conducted with 26 subjects (age: 22.00 ± 2.06 y; height: 168.77 ± 8.07 cm; mass: 70.98 ± 13.14 kg; BMI: 24.75 ± 3.04 kg/m2; 6 males; 20 females). The presence of scapular dyskinesis was determined visually using the scapular dyskinesis test with a dichotomous outcome (yes/no). Strength of the scapular stabilizers and rotator cuff was assessed via manual muscle testing using a handheld dynamometer. Force measures obtained with the handheld dynamometer were used to quantify strength. For each muscle tested, the mean peak force of three trials were normalized to body weight and used for data analysis. Additionally, strength ratios were calculated and analyzed. Differences in strength and strength ratios between those with and without scapular dyskinesis were compared using separate two-way mixed ANOVAs with repeated measures. RESULTS: No significant differences for either strength (F1.83,43.92 = 1.10, p = .34) or strength ratios (F1.83,44.02 = 1.93, p = .16) were observed between those with and without scapular dyskinesis. A significant main effect (F1.83,43.92 = 239.32, p < .01) for muscles tested was observed, and post-hoc analysis revealed significant trends resulting in a generalized order: the upper trapezius generated the greatest amount of force, followed by serratus anterior and middle trapezius, lower trapezius, supraspinatus, medial rotators, and lateral rotators. CONCLUSION: The results of this study indicate that differences in shoulder muscle strength do not exist between healthy subjects with and without scapular dyskinesis. Additionally, scapular dyskinesis appears to be prevalent in healthy populations. LEVEL OF EVIDENCE: Level 3.

The independent and interactive effects of navicular drop and quadriceps angle on neuromuscular responses to a weight-bearing perturbation.

CONTEXT: Little is known about the effects of static alignment on neuromuscular control of the knee during dynamic motion. OBJECTIVE: To evaluate the isolated and combined effects of quadriceps angle (QA) and navicular drop (ND) on neuromuscular responses to a weight-bearing perturbation. DESIGN: Mixed-model, repeated-measures design. SETTING: Sports medicine and athletic training research laboratory. PATIENTS OR OTHER PARTICIPANTS: Seventy-nine National Collegiate Athletic Association Division I collegiate female athletes, classified with below-average ND and QA (LND-LQA); below-average ND and above-average QA (LND-HQA); above-average ND and below-average QA (HND-LQA); or above-average ND and QA (HND-HQA). INTERVENTION(S): A lower extremity perturbation device produced a forward and either internal or external rotation of the trunk and femur on the weight-bearing tibia to evoke a reflex response. MAIN OUTCOME MEASURE(S): Neuromuscular responses were examined in the quadriceps, hamstrings, and gastrocnemius muscles: preperturbation amplitude 50 milliseconds before the perturbation, reflex time, and postperturbation amplitude 150 milliseconds immediately postperturbation. RESULTS: Navicular drop had the greatest effect on preperturbation amplitude of the lateral hamstrings and postperturbation amplitude of all muscles, with greater activation amplitude noted in subjects in the HND classifications. Quadriceps angle primarily affected reflex time of the quadriceps; in subjects with LQA, reflex time was faster for internal rotation than external rotation perturbations. The interaction between ND and QA had the greatest effect on reflex time of the lateral hamstrings. For internal rotation perturbations, subjects in the LND classifications had faster reflex times in the lateral hamstrings if they had HQA values rather than LQA values. With external rotation perturbations, HND-LQA subjects had slower reflex times than those in all other alignment classifications. CONCLUSIONS: Navicular drop and QA have both independent and interactive effects on neuromuscular responses to a weight-bearing, rotational perturbation. These interactive effects highlight the importance of considering the entire lower extremity posture rather than a single alignment characteristic, given the potential for one alignment factor to compensate for or interact with another.

Fatigue, vertical leg stiffness, and stiffness control strategies in males and females.

CONTEXT: Fatigue appears to influence musculoskeletal injury rates during athletic activities, but whether males and females respond differently to fatigue is unknown. OBJECTIVE: To determine the influence of fatigue on vertical leg stiffness (K (VERT)) and muscle activation and joint movement strategies and whether healthy males and females respond similarly to fatigue. DESIGN: Repeated-measures design with all data collected during a single laboratory session. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Physically active males (n = 11) and females (n = 10). INTERVENTION(S): Subjects performed hopping protocols at 2 frequencies before and after fatigue, which was induced by repeated squatting at submaximal loads. MAIN OUTCOME MEASURE(S): We measured K (VERT) with a forceplate and peak muscle activity of the quadriceps, hamstrings, gastrocnemius, soleus, and anterior tibialis muscles with surface electromyography. Sagittal-plane kinematics at the knee and ankle were recorded with an electrogoniometer. RESULTS: After fatigue, K (VERT) was unchanged for all subjects. However, both males and females demonstrated reduced peak hamstrings ( P = .002) and anterior tibialis ( P = .001) activation, coupled with increased gastrocnemius ( P = .005) and soleus ( P = .001) peak activity, as well as increased quadriceps-hamstrings ( P = .005) and gastrocnemius/soleus-anterior tibialis coactivation ratios ( P = .03) after fatigue. Overall, females demonstrated greater quadriceps-hamstrings coactivation ratios than males, regardless of the fatigue condition ( P = .026). Only females showed increased knee flexion at initial contact after fatigue during hopping ( P = .03). CONCLUSIONS: Although K (VERT) was unaffected, the peak muscle activation and joint movement strategies used to modulate K (VERT) were affected after fatigue. Once fatigued, both males and females used an ankle-dominant strategy, with greater reliance on the ankle musculature and less on the knee musculature. Also, once fatigued, all subjects used an antagonist inhibition strategy by minimizing antagonist coactivation. Overall, females used a more quadriceps-dominant strategy than males, showing greater quadriceps activity and a larger quadriceps-hamstrings coactivation ratio. Changes in muscle activation and coactivation ratios because of fatigue and sex are suggested to alter knee joint stability and increase anterior cruciate ligament injury risk.

COMPARISON OF RANGE OF MOTION, STRENGTH, AND HOP TEST PERFORMANCE OF DANCERS WITH AND WITHOUT A CLINICAL DIAGNOSIS OF FEMOROACETABULAR IMPINGEMENT.

BACKGROUND: Dancers commonly experience anterior hip pain caused by femoroacetabular impingement (FAI) that interrupts training and performance in dance. A paucity of literature exists to guide appropriate evaluation and management of FAI among dancers. PURPOSE: The purpose of this study was to determine if dancers with clinical signs of FAI have differences in hip range of motion, strength, and hop test performance compared to healthy dancers. STUDY DESIGN: Quasi-experimental, cohort comparison. METHODS: Fifteen dancers aged between 18- 21 years with clinical signs of FAI that included anterior hip pain and provocative impingement tests were compared to 13 age-matched dancers for passive hip joint range of motion, isometric hip strength, and performance of the medial triple hop, lateral triple hop, and cross-over hop tests. RESULTS: No statistically significant differences in range of motion were noted for flexion (Healthy = 145° + 7°; FAI = 147° + 10°; p=0.59), internal rotation (Healthy = 63° + 7°; FAI = 61° + 11°; p=0.50), and external rotation (Healthy = 37° + 9°; FAI = 34° + 12°; p=0.68) between the two groups. Hip extension strength was significantly less in the dancers with FAI (224 + 55 Newtons) compared to the healthy group (293 ± 58 Newtons; F(1,26) = 10.2; p=0.004). No statistically significant differences were noted for flexion, internal rotation, external rotation, abduction, or adduction isometric strength. The medial triple hop test was significantly less in the FAI group (354 ± 43 cm) compared to the healthy group (410 ± 50 cm; F(1,26) = 10.3; p = 0.004). Similar results were observed for the lateral hop test, as the FAI group (294 ± 38 cm) performed worse than the healthy controls (344 ± 54cm; F(1,26) = 7.8; p = 0.01). There was no statistically significant difference between the FAI group (2.7 ± 0.92 seconds) and the healthy group (2.5 ± 0.75 seconds) on the crossover hop test. CONCLUSION: Dancers with FAI have less strength of the hip extensors and perform worse during medial and lateral hop triple tests compared to healthy dancers. Clinicians may use this information to assist in screening of dancers with complaints of hip pain and to measure their progress for return to dance. LEVEL OF EVIDENCE: 3B, non-consectutive cohort study.

Gender differences in leg stiffness and stiffness recruitment strategy during two-legged hopping.

The authors compared leg stiffness (K(VERT)), muscle activation, and joint movement patterns between 11 men and 10 women during hopping. Physically active and healthy men and women performed continuous 2-legged hopping at their preferred rate and at 3.0 Hz. Compared with men, women demonstrated decreased K(VERT); however, after the authors normalized for body mass, gender differences in K(VERT) were eliminated. In comparison with men, women also demonstrated increased quadriceps and soleus activity, as well as greater quadriceps-to-hamstrings coactivation ratios. There were no significant gender differences for joint movement patterns (p>.05). The relationship between the observed gender differences in muscle recruitment and the increased risk of anterior cruciate ligament injury in women requires further study.

An outcome study of chronic Achilles tendinosis after excision of the Achilles tendon and flexor hallucis longus tendon transfer.

BACKGROUND: A number of operative techniques, including decompression with debridement and flexor hallucis longus (FHL) tendon augmentation, have been described for chronic degenerative Achilles tendinosis. Decompression with debridement has been shown to be effective; however, pain and functional limitation can persist in individuals with more severe tendon involvement. Augmentation with the FHL tendon can add mechanical support; however, difficulty in achieving proper tendon tensioning and the potential to leave behind painful diseased tendon are disadvantages of the technique. The purpose of this study was to present the results of a modified technique in which the Achilles tendon is completely excised and the FHL tendon is transferred. METHODS: Fifty-six surgeries using this modified technique were done between October, 1994, and March, 2002, for patients with chronic degenerative Achilles tendinosis. Forty-four patients with and average age of 58.2 (SD 10.1) years and an average time of followup of 3.4 (SD 1.9) years were available for testing. All subjects were mailed a packet of standardized questionnaire information that included the Self-Reported Health Related Quality of Life measures Short Form (SF-36) and the subjective component of the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle and Hindfoot Score. Nineteen patients returned to the clinic for objective assessment. Statistical analysis tested for a difference in the SF-36 scores between our subjects and the general United States population and for a difference in strength and range of motion between the involved and uninvolved lower extremities. RESULTS: Pain decreased in 95.5% (n = 42) patients, and 86.4% (n = 38) patients were satisfied with the result. There was no significant difference (p > .05) between the SF-36 scores obtained by our sample compared to the general United States population. The average AOFAS score for the 19 patients was 91.6 (SD 7.7). Dorsiflexion range of motion was not significantly different (p = 0.17); however, significant deficits were found in plantarflexion range of motion (p = 0.001) and plantarflexion strength (p < 0.025). Strength deficits were 30% on average; however, all but one patient could do a heel raise. CONCLUSION: Complete Achilles tendon excision reduces pain while preserving functional status. Although strength deficits persisted, these deficits did not seem to affect the functional status in this sample of patients.