Context:Enhancing core stability through exercise is common to musculoskeletal injury prevention programs. Definitive evidence demonstrating an association between core instability and injury is lacking; however, multifaceted prevention programs including core stabilization exercises appear to be effective at reducing lower extremity injury rates.Evidence Acquisition:PubMed was searched for epidemiologic, biomechanic, and clinical studies of core stability for injury prevention (keywords: “core OR trunk” AND “training OR prevention OR exercise OR rehabilitation” AND “risk OR prevalence”) published between January 1980 and October 2012. Articles with relevance to core stability risk factors, assessment, and training were reviewed. Relevant sources from articles were also retrieved and reviewed.Results:Stabilizer, mobilizer, and load transfer core muscles assist in understanding injury risk, assessing core muscle function, and developing injury prevention programs. Moderate evidence of alterations in core muscle recruitment and injury risk exists. Assessment tools to identify deficits in volitional muscle contraction, isometric muscle endurance, stabilization, and movement patterns are available. Exercise programs to improve core stability should focus on muscle activation, neuromuscular control, static stabilization, and dynamic stability.Conclusion:Core stabilization relies on instantaneous integration among passive, active, and neural control subsystems. Core muscles are often categorized functionally on the basis of stabilizing or mobilizing roles. Neuromuscular control is critical in coordinating this complex system for dynamic stabilization. Comprehensive assessment and training require a multifaceted approach to address core muscle strength, endurance, and recruitment requirements for functional demands associated with daily activities, exercise, and sport.

Medial tibial stress syndrome (MTSS) is a common injury in runners and military personnel. There is a lack of agreement on the aetiological factors contributing to MTSS, making treatment challenging and highlighting the importance of preventive efforts. Understanding the risk factors for MTSS is critical for developing preventive measures. The purpose of this systematic review and meta-analysis was to assess what factors put physically active individuals at risk to develop MTSS. Selected electronic databases were searched. Studies were included if they contained original research that investigated risk factors associated with MTSS, compared physically active individuals with MTSS and physically active individuals without MTSS, were in the English language and were full papers in peer-reviewed journals. Data on research design, study duration, participant selection, population, groups, MTSS diagnosis, investigated risk factors and risk factor definitions were extracted. The methodological quality of the studies was assessed. When the means and SDs of a particular risk factor were reported three or more times, that risk factor was included in the meta-analysis. There were 21 studies included in the systematic review and nine risk factors qualified for inclusion in the meta-analysis. Increased BMI (weighted mean difference (MD)=0.79, 95% CI 0.38 to 1.20, p<0.001), navicular drop (MD=1.19 mm, 95% CI 0.54 to 1.84, p<0.001), ankle plantarflexion range of motion (ROM; MD=5.94°, 95% CI 3.65 to 8.24, p<0.001) and hip external rotation ROM (MD=3.95°, 95% CI 1.78 to 6.13, p<0.001) were risk factors for MTSS. Dorsiflexion and quadriceps-angle were clearly not risk factors for MTSS. There is a need for high-quality, prospective studies using consistent methodology evaluating MTSS risk factors. Our findings suggest that interventions focused on addressing increased BMI, navicular drop, ankle plantarflexion ROM and hip external rotation ROM may be a good starting point for preventing and treating MTSS in physically active individuals such as runners and military personnel.

The study findings add to the growing body of evidence that suggests an absence of chronic hip ROM adaptations. It is therefore suggested that in the hip, unlike the glenohumeral joint, symmetry in ROM between player positions and dominant and nondominant sides should be expected in healthy professional baseball pitchers and position players.

The functional movement screen (FMS) is commonly used to assess movement capacity and determine injury risk. Evidence suggests that athletes who score 14 points or less on the FMS are at increased risk for injury, but differences between males and females have been minimally studied. The purpose of this study was to investigate sex differences in FMS scores of secondary school athletes. Using a cross-sectional study design, 60 healthy secondary school athletes performed the FMS, which is composed of 7 functional movement tasks (deep squat, hurdle step, inline lunge, shoulder mobility, active straight-leg raise, trunk stability push-up, and rotary stability) and 3 clearance screens. Dependent variables were FMS total composite score and individual task scores; secondary analyses were performed using total research score and individual task research scores when indicated. Lower scores indicated functional movement deficits and increased injury risk. Healthy secondary school female athletes scored lower on the total composite (p = 0.004) than healthy secondary school male athletes. Females also scored lower on the following individual FMS tasks: inline lunge (p < 0.04) and trunk stability push-up (p = 0.001). Healthy secondary school female athletes scored 14 or less on the FMS total composite score and significantly lower in general compared with healthy secondary school male athletes, which suggests these female athletes may be at higher risk for injury. Factors that may contribute to increased injury risk include deficits in mobility, core stabilization, and coordinated movement patterns. Clinicians should be aware of possible sex differences when using the FMS and developing injury prevention programs.

Context: The repetitive demands of throwing affect glenohumeral (GH) range of motion (ROM) and strength. Less is known about hip alterations in skeletally immature athletes.Objective: To compare GH and hip ROM and strength between age, position, and side of youth baseball athletes.Design: Cross-sectional study. Main Outcome Measure(s): Bilateral GH and hip internaland external-rotation ROM were measured passively and summed for total arc of motion (TAM). Glenohumeral and hip rotation and gluteus medius strength were measured. Analyses included linear mixed models.Results: Glenohumeral internal rotation was less in throwing than in nonthrowing arms (P , .05) except in younger pitchers (P ¼ .86). Compared with older athletes, younger athletes had more GH external rotation (103.38 6 7.78 versus 97.58 6 9.48; P ¼ .002), TAM (156.48 6 8.78 versus 147.98 6 10.98; P ¼ .04), and external rotation in throwing compared with nonthrowing arms (101.98 6 1.28 versus 97.98 6 1.18; P , .001). Glenohumeral TAM was less in throwing than in nonthrowing arms (150.58 6 2.18 versus 154.98 6 1.38; P ¼ .01). Younger athletes had more hip internal rotation (38.98 6 6.88 versus 31.28 6 7.58; P , .001) and TAM (68.48 6 10.08 versus 60.78 6 9.88; P ¼ .001) than older athletes. Lead-leg hip internal-rotation ROM was greater than in the stance leg (34.88 6 8.98 versus 32.88 6 7.78; P ¼ .01). Overall, older players were stronger than younger players (P , .05), and the throwing arm was stronger in internal rotation than the nonthrowing arm (10.12 6 3.72 lb [4.59 6 1.69 kg] versus 9.43 6 3.18 lb [4.28 6 1.44 kg]; P ¼ .047).Conclusions: Youth baseball athletes had typical GH ROM adaptations of less internal rotation and more external rotation in the throwing versus the nonthrowing arm. Greater ROM in younger athletes may be explained by prepubertal characteristics. We obtained hip-strength values in youth baseball athletes, and as expected, older athletes were stronger.Key Words: shoulder, kinetic chain, adolescents, throwing athletes Key PointsYouth baseball athletes showed glenohumeral and hip adaptations between age groups. Glenohumeral range-of-motion adaptations typical in baseball athletes-less internal rotation and more external rotation-were present in participants as young as 8 years old.

Clinical Scenario: Research has shown a link between poor core stability and chronic, nonspecific low back pain, with data to suggest that alterations in core muscle activation patterns, breathing patterns, lung function, and diaphragm mechanics may occur. Traditional treatment approaches for chronic, nonspecific low back pain focus on exercise and manual therapy interventions, however it is not clear whether breathing exercises are effective in treating back pain. Focused Clinical Question: In adults with chronic, nonspecific low back pain, are breathing exercises effective in reducing pain, improving respiratory function, and/or health related quality of life? Summary of Key Findings: Following a literature search, 3 studies were identified for inclusion in the review. All reviewed studies were critically appraised at level 2 evidence and reported improvements in either low back pain or quality of life following breathing program intervention. Clinical Bottom Line: Exercise programs were shown to be effective in improving lung function, reducing back pain, and improving quality of life. Breathing program frequencies ranged from daily to 2-3 times per week, with durations ranging from 4 to 8 weeks. Based on these results, athletic trainers and physical therapists caring for patients with chronic, nonspecific low back pain should consider the inclusion of breathing exercises for the treatment of back pain when such treatments align with the clinician's own judgment and clinical expertise and the patient's preferences and values. Strength of Recommendation: Grade B evidence exists to support the use of breathing exercises in the treatment of chronic, nonspecific low back pain.

Physical examination tests may aid diagnosis; 6 tests are recommended for confirming and 1 test is recommended for ruling out a SLAP lesion. Combinations of tests may be helpful to diagnose SLAP lesions. Clinical trials directly comparing outcomes between surgical and nonoperative management are absent; however, in cohort trials, the reports of function and return-to-sport outcomes are similar for each management approach. Nonoperative management that includes rehabilitation, nonsteroidal anti-inflammatory drugs, and corticosteroid injections is recommended as the first line of treatment. Rehabilitation should address deficits in shoulder internal rotation, total arc of motion, and horizontal-adduction motion, as well as periscapular and glenohumeral muscle strength, endurance, and neuromuscular control. Most researchers have examined the outcomes of surgical management and found high levels of satisfaction and return of shoulder function, but the ability to return to sport varied widely, with 20% to 94% of patients returning to their sport after surgical or nonoperative management. On average, 55% of athletes returned to full participation in prior sports, but overhead athletes had a lower average return of 45%. Additional work is needed to define the criteria for diagnosing and guiding clinical decision making to optimize outcomes and return to play.

Context: Alterations in scapular muscle activation, which are common with glenohumeral (GH) injuries, affect stability and function. Rehabilitation aims to reestablish activation between muscles for stability by progressing to whole-body movements.Objective Design: Cross-sectional study. Setting: Laboratory.Patients or Other Participants: Thirty-nine participants who had GH injuries (n ¼ 20; age ¼ 23.6 6 3.2 years, height ¼ 170.7 6 11.5 cm, mass ¼ 74.7 6 13.1 kg) or were healthy (n ¼ 19; age ¼ 24.4 6 3.3 years, height ¼ 173.6 6 8.6 cm, mass ¼ 74.7 6 14.8 kg) were tested.Intervention(s): Clinical examination confirmed each participant's classification as GH injury or healthy control. Participants performed 4 exercises (bow and arrow, external rotation with scapular squeeze, lawnmower, robbery) over 3 seconds with no load while muscle activity was recorded.Main Outcome Measure(s): We used surface electromyography to measure UT, MT, LT, and SA muscle activity. Scapular muscle-activation ratios (UT:MT, UT:LT, and UT:SA) were calculated (normalized mean electromyography of the UT divided by normalized mean electromyography of the MT, LT, and SA). Exercise 3 group analyses of variance with repeated measures were conducted.Results: No group differences for activation ratios or individual muscle activation amplitude were found (P . .05). Similar UT:MT and UT:LT activation ratios during bow-andarrow and robbery exercises were seen (P . .05); both had greater activation than external-rotation-with-scapular-squeeze and lawnmower exercises (P , .05). The bow-and-arrow exercise elicited the highest activation from the UT, MT, and LT muscles; SA activation was greatest during the externalrotation-with-scapular-squeeze exercise.Conclusions: Scapular muscle activation was similar between participants with GH injuries and healthy control participants when performing the unloaded multiplanar, multijoint exercises tested. High activation ratios during the bow-andarrow exercise indicate UT hyperactivity or decreased MT, LT, and SA activity. Our GH injury group may be comparable to high-functioning injured athletes. Study results may assist clinicians in selecting appropriate exercises for scapular muscle activation when caring for injured athletes.Key Words: force couple, glenohumeral joint, rehabilitation, serratus anterior muscle, trapezius muscle Key PointsMuscle balance to promote scapular upward rotation, as indicated by muscle-activation ratios, was present and similar between participants with glenohumeral injuries and healthy control participants when performing 4 unloaded multiplanar, multijoint functional exercises. Clinicians should use caution when prescribing the bow-and-arrow exercise because it produced high scapular muscle-activation ratios, indicating upper trapezius hyperactivity and decreased middle trapezius, lower trapezius, and serratus anterior activity. Exercises that promote activation of the middle trapezius, lower trapezius, and serratus anterior muscles while minimizing upper trapezius hyperactivity are ...