Kinetic chain revisited: consensus expert opinion on terminology, clinical reasoning, examination, and treatment in people with shoulder pain.

BACKGROUND: The purpose of this study was to reach consensus on the most appropriate terminology and issues related to clinical reasoning, examination, and treatment of the kinetic chain (KC) in people with shoulder pain among an international panel of experts. METHODS: A 3-round Delphi study that involved an international panel of experts with extensive clinical, teaching, and research experience in the study topic was conducted. A search equation of terms related to the KC in Web of Science and a manual search were used to find the experts. Participants were asked to rate items across 5 different domains (terminology, clinical reasoning, subjective examination, physical examination, and treatment) using a 5-point Likert-type scale. An Aiken coefficient of validity (V) ≥0.7 was considered indicative of group consensus. RESULTS: The participation rate was 30.2% (n = 16), whereas the retention rate was high throughout the 3 rounds (100%, 93.8%, and 100%). A total of 15 experts from different fields and countries completed the study. After the 3 rounds, consensus was reached on 102 items: 3 items were included in the "terminology" domain; 17 items, in the "rationale and clinical reasoning" domain; 11 items, in the "subjective examination" domain; 44 items, in the "physical examination" domain; and 27 items, in the "treatment" domain. Terminology was the domain with the highest level of agreement, with 2 items achieving an Aiken V of 0.93, whereas the domains of physical examination and treatment of the KC were the 2 areas with less consensus. Together with the terminology items, 1 item from the treatment domain and 2 items from the rationale and clinical reasoning domain reached the highest level of agreement (V = 0.93 and V = 0.92, respectively). CONCLUSION: This study defined a list of 102 items across 5 different domains (terminology, rationale and clinical reasoning, subjective examination, physical examination, and treatment) regarding the KC in people with shoulder pain. The term "KC" was preferred and a agreement on a definition of this concept was reached. Dysfunction of a segment in the chain (ie, weak link) was agreed to result in altered performance or injury to distal segments. Experts considered it important to assess and treat the KC in particular in throwing or overhead athletes and agreed that no one-size-fits-all approach exists when implementing shoulder KC exercises within the rehabilitation process. Further research is now required to determine the validity of the identified items.

Foot Strike Run Retraining for Patients With Patellofemoral Chondral Defects: A Case Series.

Military service members (SMs) demonstrate high rates of patellofemoral chondral defects (PFCDs) that are difficult to diagnosis and, if untreated, result in a cascade of events eventually leading to osteoarthritis. Running is an essential occupational task for SMs; however, there is little evidence regarding techniques to maintain running ability in individuals with cartilage defects. The purpose of this case series was to assess the clinical application of foot strike run retraining in patients with PFCDs. This case series included two active duty U.S. Marine Corps SMs who presented to outpatient physical therapy with PFCD, diagnosed via MRI. Both patients attended eight foot strike run retraining sessions. Running mechanics and patient-reported outcomes were recorded pre-training, post-training, and at a 1-month follow-up visit. Both patients successfully converted their strike pattern from a rearfoot to a non-rearfoot strike pattern with training and retained this strategy at 1-month follow-up. Post-intervention, both patients demonstrated increased running tolerance, and improvements in Numeric Pain Rating Scale and Lower Extremity Functional Scale scores. Biomechanical analysis showed that both patients demonstrated a 63% to 70% reduction in average and peak vertical ground reaction force loading rates post-treatment. Modification of foot strike pattern from rear to non-rearfoot strike during running for individuals with PFCD can reduce the magnitude of impact loading, which potentially limits disease progression. These findings suggest that foot strike run retraining may be a feasible strategy to reduce pain and improve function in SMs with PFCD who are required to run for occupational responsibilities.

Donor Limb Functional Restoration via a Novel Clinical Care Pathway following Fibula Free Flap Harvest for Head and Neck Reconstruction.

Patients undergoing head and neck skeletal reconstruction (HNR) often require free tissue transfer from the extremities to ensure proper restoration of form and function. This requires a team-based, highly reliable medical system centered around the patient needs. Surgical intervention across multiple sites and harvesting of donor tissue results in short- and long-term physical impairments. There is a paucity of research objectively measuring impairments resulting from the graft donor site. There is a lack of research that objectively measures impairments and protocols for the management of these patients postoperatively. Patients undergo little, if any, formal approach to dealing with the vast impairments, which are sequelae to this surgery. This leads to large discrepancies in proposed functional progressions, return to duty timelines, and utilization of rehabilitative resources. At a major military medical center, an innovative clinical care pathway for patients undergoing HNR using free tissue transfer was implemented using a multidisciplinary model that focuses on early engagement with rehabilitation. This model, paired with a single surgery, will attempt to return service members to duty months earlier than the traditional approach. This report describes the conceptual framework and implementation of a new criteria-based, multidisciplinary clinical care pathway for HNR patients. The collaboration amongst the multidisciplinary care team has optimized the holistic health of the patient and communication with their support network, yielding faster return to normalization of daily life activities. The long-term goal is to further develop and formalize this pathway to best serve this patient population.

Objective and subjective measures to guide upper extremity return to sport testing: A modified Delphi survey.

OBJECTIVE: To identify which subjective and objective tests do content experts utilize to help guide return to sport (RTS) decision making for an athlete after an upper extremity (UE) injury? METHODS: A modified Delphi survey was utilized, including content experts in UE rehabilitation. Survey items were identified based on a literature review identifying current best evidence and practice for UE RTS decision making. Content experts (n = 52) were identified, having a minimum of 10 years of experience with rehabilitation of UE athletic injuries, and 5 years of experience using an UE RTS algorithm to guide decision making. RESULTS: Expert consensus was achieved on a combination of tests utilized within an UE RTS algorithm: 1. Tissue healing time frame is an important consideration in RTS decision making; 2. Patient reported outcome measures should be utilized specifically, DASH and NPRS 3. Strength is measured by handheld dynamometer and is an important consideration. 4. ROM should be utilized and is an important consideration. 5. Physical performance tests utilized include: Closed Kinetic Chain Upper Extremity Stability test, Seated shot-put test and lower extremity/core tests. CONCLUSIONS: This survey reached expert consensus on which subjective and objective measures to utilize to evaluate RTS readiness after UE injury.

The association between kinesiophobia and functional limitations in service members with knee pain.

BACKGROUND: Knee diagnoses account for more than 50% of lower extremity musculoskeletal conditions in non-deployed US Service members. However, there is limited information regarding kinesiophobia in Service members with non-operative knee diagnoses. HYPOTHESES: The objectives of this study were to determine the prevalence of high levels of kinesiophobia in US military Service members with knee pain across different knee diagnoses, and to determine the relationships between kinesiophobia and lower extremity function and/or specific functional limitations in Service members with knee pain. It was hypothesized Service members with knee pain would exhibit high levels of kinesiophobia across all knee diagnoses examined, and higher levels of both kinesiophobia and pain would be associated with worse self-reported function in this population. It was also hypothesized higher levels of kinesiophobia would be associated with functional activities with high knee loading. DESIGN: Retrospective cohort study. LEVEL OF EVIDENCE: IV. METHODS: Sixty-five US Service members presenting to an outpatient physical therapy clinic were included in this study (20 females; age = 30.8 ± 7.7 years; height = 1.74 ± 0.9 m; mass = 80.7 ± 16.2 kg). Inclusion criterion was the presence of knee pain (duration = 50 ± 59 months); exclusion criterion was knee pain as a sequela of knee surgery. Data regarding demographic, pain chronicity, pain by Numeric Rating Scale (NRS), Tampa Scale of Kinesiophobia (TSK), and Lower Extremity Functional Scale (LEFS) were retrospectively obtained from patients' medical records. A high level of kinesiophobia was defined as a TSK score of greater than 37 points. Patient diagnoses included: osteoarthritis (n = 16); patellofemoral pain syndrome (n = 23); and other non-operative knee diagnoses (n = 26). Commonality analysis was utilized to determine the effects of age, height, mass, NRS, and TSK on LEFS score. Predictor values were interpreted as <1% = negligible, >1% = small; >9% = moderate, >25% = large. Additionally, exploratory item-specific analyses examined the strength of the relationships between kinesiophobia and LEFS item responses. Binary logistic regression determined if difficulty with an individual LEFS item could be predicted from either NRS or TSK score. Statistical significance was set at P < 0.05. RESULTS: High levels of kinesiophobia were identified in 43 individuals (66%). NRS and TSK explained 19.4% and 8.6% of the unique variance in LEFS, and 38.5% and 20.5% of total variance, respectively. Age, height, and mass explained negligible to small proportions of the unique variance in LEFS. TSK and NRS were independent predictors for 13/20 individual LEFS items, with odds ratios ranging from 1.12 to 3.05 (P < 0.05). CONCLUSION: The majority of US Service members in this study exhibited high levels of kinesiophobia. Kinesiophobia was significantly related to self-reported functional scores and performance on individual functional tasks in Service members with knee pain. CLINICAL RELEVANCE: Treatment strategies addressing both fear of movement and pain reduction in patients with knee pain may help optimize functional outcomes.

Traumatic Hip Dislocation in an NCAA DI Football Player with Occult Sequelae: A Case Report.

BACKGROUND AND PURPOSE: American football generates the most sports-related injuries in the United States, with tackling as the leading injury mechanism. Overall injury rate at the collegiate level has been reported as 8.61 per 1,000 athlete exposures (AEs) - twice the rate of high school levels; competition injury rates are reported as high as 36.94/1000 AEs. Traumatic hip dislocation is an uncommon injury typically arising from high-energy axial impact with only 2-5.5% occurring during sports activities. CASE DESCRIPTION: A 22-year-old NCAA Division I football defensive back who experienced extreme left hip pain following contact with another player with his hip flexed during a game was diagnosed with a type 1 posterior hip dislocation, a grade 1 medial collateral ligament sprain with concomitant posterior thigh and hip muscle strains. Key impairments were limited left lower extremity motor performance, range of motion deficits, left hip pain, and diminished function and weight-bearing ability. OUTCOMES: The athlete reintegrated into typical defensive back off-season training approximately four to five months post injury without restrictions, however presented with new anterior hip pain seven months post injury revealing occult sequelae requiring surgical intervention. He was able to return to full play the following football season. DISCUSSION: This case report describes the successful return to sport of a Division I football player who sustained a traumatic posterior hip dislocation and complicated course including surgical intervention secondary to associated sequelae. LEVEL OF EVIDENCE: 5.

Prediction of ACL Injuries from Vertical Jump Kinetics in Division 1 Collegiate Athletes.

BACKGROUND: The incidence of ACL injuries continues to rise secondary to an increase in sport participation. Evidence supports the use of force plate testing to quantify kinetics during rehabilitation after injury and recovery; however, there is limited current research regarding if jump kinetics can identify athletes who are at higher risk for injury. Altered kinetics could potentially lead to abnormal force dissipation and resultant injury. PURPOSE: The purpose of this investigation was to identify whether the force-time variables from vertical jumps could predict ACL injuries in collegiate athletes. STUDY DESIGN: Retrospective cohort. METHODS: Vertical jump testing is performed by all healthy varsity collegiate athletes at several intervals throughout the athletic year at a Division I institution using a commercially available force plate system with dedicated software. Athletes who sustained an ACL injury between 1/1/15 and 6/1/19 were identified (n=16) and compared to healthy athletes who participated in the same sports (n = 262). ACL injuries were considered for this study if they occurred no more than 10 weeks after a jump test. The outcome variables were load, explode, and drive, operationally defined as the average eccentric rate of force development, average relative concentric force, and concentric relative impulse, respectively, which the system normalized to T scores. Mann-Whitney U tests were used to assess group differences for load, explode, drive, and the ratio between the variables. Logistic regression was used to determine if the battery of variables could predict whether or not an athlete would sustain an ACL injury. The p-value was set to 0.10 for the Mann-Whitney U tests, and 0.05 for the logistic regression. RESULTS: Significant differences between the ACL and healthy groups were seen for explode (p=0.08), drive (p=0.06), load:explode ratio (p=0.06), and explode:drive ratio (p=0.03). Explode and drive, when entered into the regression equation, showed the ability to predict injury, χ 2 = 6.8, df = 2, p=0.03. CONCLUSIONS: The vertical jump force plate variables were able to identify athletes who sustained an ACL injury within 66 days of testing. Athletes who sustained an ACL injury demonstrated altered kinetics and less ability to transmit forces during the vertical jump. LEVEL OF EVIDENCE: 3.

Implementation of an Injury Prevention Program in NCAA Division I Athletics Reduces Injury-Related Health Care Costs.

BACKGROUND: The estimated cost per year of injuries in collegiate athletics has been reported to be billions of dollars in the United States. Injury prevention programs are often assessed only by their ability to reduce injuries, and there is little evidence of any potential reduction in associated health care costs. PURPOSE: To investigate changes in injury-related health care costs at a National Collegiate Athletic Association (NCAA) Division I university after the implementation of an injury prevention program. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Included were 12 sports teams that used the injury prevention program (user group) and 16 teams that did not implement the program (nonuser group). The injury surveillance and prevention system (Sparta Science) utilized a commercially available force-plate system to assess kinematic variables, flag high-risk athletes, and guide individual conditioning programs. Data were obtained from 3 academic years before (2012-2014) and 2 academic years after (2015-2016) implementation of the Sparta Science system. The number of injuries and associated health care costs (surgery, clinic visits, imaging, and physical therapy) were compared between users and nonusers. RESULTS: Total average annual injuries did not change significantly between users and nonusers after implementation of the program; however, users demonstrated a 23% reduction in clinic visits as compared with a 14% increase for nonusers (P = .049). Users demonstrated a 13% reduction in associated health care encounters, compared with a 13% increase for nonusers (P = .032). Overall health care costs changed significantly for both groups, with an observed 19% decrease ($2,456,154 to $1,978,799) for users and an 8% increase ($1,177,542 to $1,270,846) for nonusers (P < .01 for both). Costs related to associated health care encounters also decreased by 20% for users as compared with a 39% increase for nonusers (P = .027). CONCLUSION: This study demonstrated the ability to significantly reduce injury-related health care costs in NCAA Division I athletes via a comprehensive injury surveillance and prevention program utilizing force-plate technology. Given the substantial and appropriate focus on value of care delivery across the US health care system, we recommend the continued study of sports injury surveillance and prevention programs for reducing injury-related health care costs.

REPEATABILITY OF SWAY MEASURES IN UPPER EXTREMITY WEIGHT-BEARING.

BACKGROUND: Analysis of upper extremity weight bearing ability is important for athletes as some function largely in a closed chain capacity (e.g., wrestling, football, gymnastics); also, all require closed chain upper extremity function during strength and conditioning. Additionally, in a rehabilitation setting, closed chain upper extremity functional testing is often used as a return to play criterion. Lower extremity sway measures (biomechanical and clinical) have been published widely and have established reliability and validity; however, the reliability of upper extremity sway biomechanical measures has not been investigated to date. HYPOTHESIS/PURPOSE: The purpose of this study was to determine the repeatability of a variety of force plate measurements during an upper extremity task in an athletic population. It was hypothesized that variables measuring upper extremity sway in a closed kinetic chain position would have excellent reliability. STUDY DESIGN: Cross-sectional. METHODS: All data were collected using a force plate system with commercially available software. Four hundred and ninety healthy Division I athletes were tested for both their dominant and non-dominant upper extremity at one of two testing sessions. Subjects were instructed to stay as still as possible while maintaining a full plank position with one upper extremity on the force plate and the contralateral upper extremity behind their back. Two, 20-second trials were performed for each extremity. Variables measured included average sway velocity (ASV), sway velocity in medial-lateral (SVML) and anterior-posterior (SVAP) directions, sway velocity at 1st and 2nd time intervals for AP (VAP1 and 2) and ML (VML1 and 2) directions, and sway frequency in the AP direction for 1st and 2nd time intervals (FreAP1 and 2). Intraclass correlation coefficients (ICC(2,1)) and their 95% confident intervals were calculated for all force plate variables for 980 limbs. RESULTS: No difference was seen between left and right extremities for any measure (p > 0.05). ICC's ranged from 0.61-0.90 for all variables, indicating moderate to excellent reliability for all variables. CONCLUSION: Upper extremity sway biomechanical variables using a force plate system have moderate to excellent reliability. These results are important prior to validation and clinical utilization of these measures including baseline testing, return to play guidelines, and injury prevention parameters. LEVEL OF EVIDENCE: 3.

Profile of upper extremity strength and function in division 1 collegiate athletes.

OBJECTIVES: To profile shoulder strength and functional test scores in collegiate athletes across various sports. DESIGN: Cross-sectional. SETTING: Pre-participation physical screens for varsity athletes at a Division I university. PARTICIPANTS: 476 healthy Division 1 collegiate athletes (270 males; 27 varsity sports). MAIN OUTCOME MEASURES: Two trials of each 1. Isometric peak force (PF) using hand-held dynamometry for shoulder internal rotation (IR), external rotation (ER), and forward elevation (FE) in kg; 2. Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST), quantified by number of touches. RESULTS: PF values (mean(SD), dominant/non-dominant) for females were: IR = 8.7(2.6)/8.7(6.2); ER = 8.2(2.5)/7.9(2.5); FE = 8.0(2.5)/8.0(2.7); CKCUEST scores were 21.8(3.9). PF values for males were: IR = 12.0(3.8)/11.9(3.6); ER = 10.7(3.4)/10.7(3.5); FE = 10.7(3.5)/10.4 (3.5); CKCUEST scores were 26.0(4.1) touches. CONCLUSIONS: Normative values should be used as an athlete's baseline for the CKCUEST. This may help target athletes who are at a higher risk of upper extremity injury and help with goals or return to sport readiness during the rehabilitation process.

USE OF AN UPPER EXTREMITY FUNCTIONAL TESTING ALGORITHM TO DETERMINE RETURN TO PLAY READINESS IN COLLEGIATE FOOTBALL PLAYERS: A CASE SERIES.

BACKGROUND/PURPOSE: Return to play decision making for upper extremity injuries is challenging due to a lack of evidence-based protocols and testing. Current guidelines utilize tests and measures with minimal evidence on re-injury risks and prediction. The purpose of this case series is to highlight a functional testing algorithm for upper extremities injuries and the outcomes for the patients that followed it. STUDY DESIGN: Case series. CASE DESCRIPTIONS: Six subjects (18 - 21 years old) who underwent shoulder capsulolabral repair secondary to recurrent instability and/or unyielding pain are included. All subjects underwent a criterion-based rehabilitation program before being assessed with the authors' upper extremity functional testing algorithm. The upper extremity functional testing algorithm consists of measures of active range of motion (AROM), passive range of motion (PROM), peak isometric force, a fatigue testing battery, and the closed kinetic chain upper extremity stability test (CKCUEST) to assess readiness for return to sport. OUTCOMES: All athletes achieved > 90% symmetry on at least two out of three tests during a fatigue testing protocol and at least 25 touches on the CKCUEST. All of the athletes returned to unrestricted football the season following surgical intervention. None of the athletes sustained an additional glenohumeral subluxation, dislocation, or upper extremity injury requiring surgical intervention for the remainder of their athletic careers (six years). DISCUSSION: The presented cases help to illustrate the effectiveness of the upper extremity functional testing algorithm to assess return to sport readiness for male collegiate football athletes. The algorithm included testing of AROM/PROM and strength that is typically used, but also included the CKCUEST and fatigue testing to further challenge and assess the upper extremity prior to returning to sports. LEVEL OF EVIDENCE: 4.

Comprehensive movement system screening tool (MSST) for athletes: Development and measurement properties.

OBJECTIVES: Non-traumatic extremity injuries are particularly common in sports, representing a significant economic, academic, and psychosocial burden on athletes. Proposed musculoskeletal risk factors for increased injury and decreased performance in athletes include movement pattern inefficiency, decreased regional stability, decreased mobility, and asymmetrical movement. The Movement System Screening Tool (MSST) is a comprehensive screening tool designed to assess these factors. Thus, the purpose of this study was to describe the development and determine the content and construct validity and inter-rater reliability of the MSST. METHODS: A modified Delphi panel of experts determined content validity. 80 athletes (40 with and 40 without a current non-traumatic shoulder injury) completed 21 clinical tests, with exploratory factor analysis and known group analysis performed to determine construct validity. Two independent raters were used to establish individual item and composite score inter-rater reliability. RESULTS: Exploratory factor analysis identified three of the four apriori constructs over 7 factors (14 tests), representing 63% of the variance. Known group analysis revealed a significantly lower composite score in athletes with vs. without a current non-traumatic shoulder injury (56.9±5.8 vs. 62.7±4.5, respectively). A preliminary cut score of 62 was chosen with sensitivity of 85% and specificity of 44%. Composite score inter-rater reliability was excellent ICC (2,1)=0.94, 95% CI (0.91, 0.96) and item reliability ranged from κ=.57 to 1.00. CONCLUSIONS: The MSST possesses constructs representative of injury risk and measurement properties acceptable for use in clinical settings. Comprehensive screens with construct validity and known measurement error are needed not only to identify athletes at risk of injury, but also provide an instrument that can be used in studies that seek to validate training approaches proposed to change movement impairment and injury risk in athletes.

Comparison of core neuromuscular control and lower extremity postural stability in athletes with and without shoulder injuries.

BACKGROUND: The kinetic chain theory is widely used as a rationale for the inclusion of core stability training in athletes. Core stability (muscle capacity and neuromuscular control) impairments may result in less than optimal performance and abnormal force dissipation to the shoulder complex that could lead to shoulder injuries. However, a paucity of literature exists to support this relationship, and no previous studies have investigated the relationship between isolated core neuromuscular control and shoulder injuries. Additionally, lower extremity postural stability has been associated with athletic function and may also be associated with shoulder injuries. The purpose of this study was to compare biomechanical measures of isolated core neuromuscular control and lower extremity postural stability between athletes with and without non-traumatic shoulder injuries. METHODS: Eighty athletes (55 males, age: 21.2 ± 3.3 years, 40 with a current shoulder injury) completed biomechanical measures of isolated core neuromuscular control and lower extremity postural stability. Athletes were matched by age, gender, body mass index, and sport type. MANOVAs were used to assess differences between measures of core neuromuscular control and lower extremity postural stability between groups. FINDINGS: There were no statistically significant differences between athletes with and without shoulder injuries for the static core neuromuscular control measures, F(4,75) = 0.45, P = 0.78, η2 = 0.02; dynamic core neuromuscular control measures, F(4,75) = 0.81, P = 0.52, η2 = 0.04; or lower extremity postural stability measures, F(8,61) = 0.85, P = 0.56, η2 = 0.10. INTERPRETATION: Although core stability is widely incorporated in rehabilitation of athletes with shoulder injuries, athletes with current non-traumatic shoulder injuries may not present with impairments in core neuromuscular control or lower extremity postural stability.

COMPARISON OF CORE STABILITY AND BALANCE IN ATHLETES WITH AND WITHOUT SHOULDER INJURIES.

BACKGROUND: Relationships between core stability and lower extremity injuries have been described in the literature; however, evidence of the relationship between upper extremity injuries and core stability and balance is limited. HYPOTHESIS/PURPOSE: The purpose of this study was to compare clinical measures of core stability and balance between athletes with and without non-traumatic shoulder injuries. STUDY DESIGN: Cross sectional. METHODS: Eighty athletes (54 males, age: 21.2 + 3.3 years) participated in this study. Forty athletes with a current shoulder injury were matched to healthy athletes by age, gender, BMI, and sport. Athletes completed clinical core stability tests including flexor and extensor endurance tests, double leg lower test (°) and balance tests including single leg stance under eyes open and eyes closed conditions, and the Y-balance test. MANOVAs were used to assess group differences. RESULTS: No statistically significant differences existed between athletes with and without shoulder injuries for clinical tests of core stability, F(1,78)=0.97, p=0.41; η2 = 0.04. No statistically significant differences existed between injured athletes with and without shoulder injuries for static and dynamic balance measures, F(1,78)=0.86, p=0.53; η2 = 0.07. CONCLUSIONS: Although core stability is widely incorporated in rehabilitation of athletes with shoulder injuries, performance on these clinical tests did not differ in the group of athletes assessed in this study. LEVEL OF EVIDENCE: 3.

Critical review of the impact of core stability on upper extremity athletic injury and performance.

BACKGROUND: Programs designed to prevent or rehabilitate athletic injuries or improve athletic performance frequently focus on core stability. This approach is based upon the theory that poor core stability increases the risk of poor performance and/or injury. Despite the widespread use of core stability training amongst athletes, the question of whether or not sufficient evidence exists to support this practice remains to be answered. OBJECTIVES: 1) Open a dialogue on the definition and components of core stability. 2) Provide an overview of current science linking core stability to musculoskeletal injuries of the upper extremity. 3) Provide an overview of evidence for the association between core stability and athletic performance. DISCUSSION: Core stability is the ability to control the position and movement of the trunk for optimal production, transfer, and control of forces to and from the upper and lower extremities during functional activities. Muscle capacity and neuromuscular control are critical components of core stability. A limited body of evidence provides some support for a link between core stability and upper extremity injuries amongst athletes who participate in baseball, football, or swimming. Likewise, few studies exist to support a relationship between core stability and athletic performance. CONCLUSIONS: A limited body of evidence exists to support the use of core stability training in injury prevention or performance enhancement programs for athletes. Clearly more research is needed to inform decision making when it comes to inclusion or emphasis of core training when designing injury prevention and rehabilitation programs for athletes.

Prediction of in-season shoulder injury from preseason testing in division I collegiate football players.

BACKGROUND: Collegiate football is a high-demand sport in which shoulder injuries are common. Research has described the incidence of these injuries, with little focus on causative factors or injury prevention. HYPOTHESIS: Football athletes who score lower on preseason strength and functional testing are more likely to sustain an in-season shoulder injury. STUDY DESIGN: Prospective, cohort study. LEVEL OF EVIDENCE: Level 2. METHODS: Twenty-six collegiate football players underwent preseason testing with a rotational profile for shoulder range of motion, isometric strength of the rotator cuff at 90° elevation and external rotation in the 90/90 position, fatigue testing (prone-Y, scaption, and standing cable press), and the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST). Data collected postseason included the type of shoulder injury and the side injured. Logistic regression was used to determine if the testing measures predicted injury, and a receiver operating characteristic curve was constructed to examine the relationship of CKCUEST to injury. RESULTS: Six athletes sustained shoulder injuries during the season. Predictor variables could significantly predict whether that player would sustain an injury during the season for both the right and left shoulders (P < 0.05). The variables that were significantly correlated with injury of the right side were forward elevation strength, prone-Y to fatigue, and the CKCUEST (P < 0.05); on the left, only the CKCUEST was significant (P < 0.05). The area under the receiver operating characteristic curve for the CKCUEST was 0.86 (ϵ = 0.87, P = 0.01). Using a score of 21 touches, the CKCUEST had a sensitivity of 0.83, a specificity of 0.79, and an odds ratio of 18.75 in determining whether a player sustained a shoulder injury. CONCLUSION: For this sample, the combination of preseason strength, fatigue, and functional testing was able to identify football players who would sustain a shoulder injury during the season. CLINICAL RELEVANCE: Using a battery of strength, fatigue, and functional testing may be helpful in identifying football players during preseason who are at a higher risk for sustaining a shoulder injury. This information can be used to optimize preseason testing and implementation of injury prevention programs.

Is there evidence to support a forefoot strike pattern in barefoot runners? A review.

CONTEXT: Barefoot running is a trend among running enthusiasts that is the subject of much controversy. At this time, benefits appear to be more speculative and anecdotal than evidence based. Additionally, the risk of injuries is not well established. EVIDENCE ACQUISITION: A PubMed search was undertaken for articles published in English from 1980 to 2011. Additional references were accrued from reference lists of research articles. RESULTS: While minimal data exist that definitively support barefoot running, there are data lending support to the argument that runners should use a forefoot strike pattern in lieu of a heel strike pattern to reduce ground reaction forces, ground contact time, and step length. CONCLUSIONS: Whether there is a positive or negative effect on injury has yet to be determined. Unquestionably, more research is needed before definitive conclusions can be drawn.

Critical review of the impact of core stability on upper extremity athletic injury and performance

BACKGROUND: Programs designed to prevent or rehabilitate athletic injuries or improve athletic performance frequently focus on core stability. This approach is based upon the theory that poor core stability increases the risk of poor performance and/or injury. Despite the widespread use of core stability training amongst athletes, the question of whether or not sufficient evidence exists to support this practice remains to be answered.OBJECTIVES: 1) Open a dialogue on the definition and components of core stability. 2) Provide an overview of current science linking core stability to musculoskeletal injuries of the upper extremity. 3) Provide an overview of evidence for the association between core stability and athletic performance.DISCUSSION: Core stability is the ability to control the position and movement of the trunk for optimal production, transfer, and control of forces to and from the upper and lower extremities during functional activities. Muscle capacity and neuromuscular control are critical components of core stability. A limited body of evidence provides some support for a link between core stability and upper extremity injuries amongst athletes who participate in baseball, football, or swimming. Likewise, few studies exist to support a relationship between core stability and athletic performance.CONCLUSIONS: A limited body of evidence exists to support the use of core stability training in injury prevention or performance enhancement programs for athletes. Clearly more research is needed to inform decision making when it comes to inclusion or emphasis of core training when designing injury prevention and rehabilitation programs for athletes.

Shoulder musculature activity and stabilization during upper extremity weight-bearing activities.

BACKGROUND: Upper extremity weight-bearing exercises are routinely used in physical therapy for patients with shoulder pathology. However, little evidence exists regarding the demand on the shoulder musculature. OBJECTIVE: To examine changes in shoulder muscle activity and center of pressure during upper extremity weight-bearing exercises of increasing difficulty. METHODS: Electromyographic (EMG) and kinetic data were recorded from both shoulders of 15 healthy subjects (10 male and 5 female). Participants were tested in a modified tripod position under three conditions of increasing difficulty: (1) hand directly on the force plate, (2) on a green Stability Trainer(™) and (3) on a blue Stability Trainer(™). Ground reaction forces were recorded for each trial. Surface EMG was recorded from the serratus anterior, pectoralis major, upper trapezius, lower trapezius, infraspinatus, anterior deltoid, posterior deltoid, and the lateral head of the triceps muscles. RESULTS: Mean deviation from center of pressure significantly increased when using the Stability Trainer(™) pads. The activities of the triceps, serratus anterior, and anterior deltoid muscles significantly increased as each trial progressed, irrespective of stability condition. Additionally, activity in the anterior deltoid, lower trapezius, and serratus anterior muscles significantly decreased with increasing difficulty, whereas activity in the triceps muscles significantly increased. DISCUSSION AND CONCLUSION: Balancing on a foam pad made it more difficult to maintain the upper extremity in a stable position. However, this activity did not alter the proprioceptive stimulus enough to elicit an increase in shoulder muscle activation. While the results on this study support the use of different level Stability Trainers(™) to facilitate neuromuscular re-education, a less compliant unstable surface may produce larger training effects.