Sport Specialization's Impact on Female Adolescent Athletes' Lower-Extremity Neuromuscular Control: A Critically Appraised Topic.

CLINICAL SCENARIO: Nearly 60 million youth ages 6-18 participate in athletics within the United States. Over the last 30 years, the outlook on youth sport participation has drastically changed, resulting in an increased emphasis on performance and college sport participation. These evolving expectations have created a sense of perfectionism, demanding more time and energy to be placed into a single sport, resulting in an increased prevalence of sport specialization, and consequently, an increased rate of injury. CLINICAL QUESTION: What is the impact of sport specialization on lower-extremity neuromuscular control in female adolescent athletes? SUMMARY OF KEY FINDINGS: Four studies were included, all comparing movement efficiency and movement patterns among multisport and sport-specialized female adolescent athletes. Three studies showed that sport specialization is associated with lower-extremity biomechanical alterations that are indicative of altered levels of neuromuscular control, which can predispose an individual to an increased risk of injury. One study concluded that no differences in neuromuscular control exist when comparing sport-specialized to multisport adolescent female athletes. CLINICAL BOTTOM LINE: Sport specialization has the potential to create negative alterations in a female adolescent athletes' lower-extremity biomechanics, leading to the creation of altered levels of neuromuscular control and a possible increased risk for injury. STRENGTH OF RECOMMENDATION: Level B evidence exists to support the conclusion that sport specialization negatively affects a female adolescent athlete's lower-extremity neuromuscular control.

Physiological and Biomechanical Differences Between Seated and Standing Uphill Cycling.

Despite differences in economy, cyclists climb in seated and standing positions. Prompted by gaps in research, we compared VO2 and heart rate (HR) (Study 1), muscle activation (Study 2) and breathing and pedaling entrainment (Study 3). METHODS: Subjects rode their bicycles on a treadmill in seated and standing positions. In Study 1, VO2 and HR of four male cyclists (21.3 ± 1.7 yrs; 69.1 ± 6 ml/kg/min) were collected, alternating positions every 5 minutes for 20 minutes (8 mph, 8% grade). In Study 2, muscle activations of eight male cyclists (24 ± 5 yrs, 67.6 ± 5.5 ml/kg/min) were collected on Rectus Femoris (RF), Biceps Femoris, Vastus Medialis (VM) and Gastrocnemius alternating positions every minute (8 mph, 8% grade). In Study 3, flow rate and entrainment of nine male cyclists (28 ± 7 yrs, 62.7 ± 7.7 ml/kg/min) were collected in 2-minute stages at 6, 8 and 10 mph, (8% grade) alternating positions every minute. RESULTS: VO2 and HR increased standing (3.17± 0.43 L/min, 175 ± 4 bpm) compared to seated (3.06 ± 0.37 L/min, 166 ± 5 bpm) (p < 0.05). Normalized EMG for RF and VM increased standing (47 ± 5%, 57 ± 15%) compared to seated (34 ± 3%, 36 ± 8%) (p < 0.05). Peak Inspiratory and Expiratory Flow increased standing (3.44±0.07 and 2.45±0.05 L/sec) compared to seated (3.09 ±0.06 and 2.21±0.04 L/sec) (p < 0.05). CONCLUSION: Uphill cycling while standing results in decreased cycling economy due to physiological and biomechanical variations compared to riding seated.

The Relationship Between Physical Characteristics and Maximal Strength in Men Practicing the Back Squat, the Bench Press and the Deadlift.

This study was designed to quantify the relationships between physical characteristics and maximal strength in the back squat, the bench press and the deadlift on powerlifters and football players. Eighteen male junior drug-tested classic powerlifters and seventeen NCAA Division II American football players' anthropometric measurements were taken to compare them with maximal strength results from either a powerlifting meet or testing from their supervised strength and conditioning program. Pearson's bivariate correlations analysis revealed (statistical significance was set at p<0.05) that individuals with a greater (Wilks points) back squat, generally presented a higher Bodyweight (BW) (r=0.37), Body Mass Index (BMI) (r=0.45), Bodyfat Percentage (BF%) (r=0.36), Hip (r=0.41), Waist (r=0.35) and Torso (r=0.41) Circumference (C), Hip C/Height (r=0.46), Waist C/Height (r=0.39) and Torso C/Height (r=0.45) ratios. The individuals with a greater bench press generally presented a higher BMI (r=0.37), Lean Body Weight (LBW) (r=0.36), Hip C (r=0.39) and Hip C/Height ratio (r=0.39). On the other hand, individuals with a greater deadlift were generally older (r=0.34), shorter (r=-0.41), had shorter thighs (r=-0.52) and trunks (r=-0.36), smaller Thigh Length (L)/Height ratio (r=-0.44), Waist C/Hip C (r=-0.41) and Thigh L/Lower Leg L (r=-0.53) ratios, but a higher Lower Leg L/Height ratio (r=-046). The results of this study should be utilized by strength and conditioning coaches to deepen their comprehension of their athletes' physical characteristics in order to help them develop strength through their advantages. Further research should focus on evaluating how physical characteristics affect performance in different squat, bench, and deadlift stances.

Impact of Splitting or Crushing on the Relative Bioavailability of the Darunavir/Cobicistat/Emtricitabine/Tenofovir Alafenamide Single-Tablet Regimen.

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) is an oral once-daily single-tablet regimen for the treatment of human immunodeficiency virus-1 infection. Different administration modalities for the D/C/F/TAF fixed-dose combination tablet were explored in this phase 1 randomized, open-label, 3-period, 3-treatment crossover study enrolling 30 healthy adults. The primary objective was to assess the relative bioavailability of each component after a single dose of D/C/F/TAF (800/150/200/10 mg) administered as a split or crushed tablet (tests) versus swallowed whole (reference). Pharmacokinetic parameters (noncompartmental analysis; logarithm-transformed) for each component were compared using linear mixed-effects modeling. For the split versus whole tablet, the bioavailabilities (maximum plasma concentration [Cmax ] and area under the plasma concentration-time curve [AUClast ]) of each D/C/F/TAF component were comparable. For the crushed versus whole tablet, the bioavailabilities of darunavir, cobicistat, and emtricitabine were comparable, except for a 17% decrease in emtricitabine Cmax ; the relative bioavailability of tenofovir alafenamide decreased by 29% and 19% for Cmax and AUClast , respectively. All intakes were safe and generally well tolerated. In summary, there was no clinically relevant impact on the bioavailability of D/C/F/TAF components when administered as a split tablet compared with a tablet swallowed whole. Administration of a crushed tablet resulted in a modest decrease in tenofovir alafenamide bioavailability; the clinical relevance of this change has not been assessed but is expected to be minimal based on the wide therapeutic window for this agent.

Imidazolylsulfonates: electrophilic partners in cross-coupling reactions.

Aryl imidazolylsulfonates participate as electrophilic coupling partners in palladium-mediated cross-coupling reactions. The aryl imidazolylsulfonates display good stability while maintaining good reactivity in a variety of palladium-catalyzed coupling reactions. Imidazolylsulfonates are a practical and economic alternative to triflates.

High-risk stress fractures: pathogenesis, evaluation, and treatment.

High-risk stress fractures require precise assessment and treatment because of their propensity for delayed union, nonunion, or complete fracture and their resulting disabling complications. Proper diagnosis necessitates a thorough clinical evaluation, centering on the patient's diet and history, particularly the training regimen. For a definitive diagnosis, plain radiography, ultrasound, bone scintigraphy, magnetic resonance imagery (MRI), and computed tomography (CT) are helpful, and each plays a specific role. High-risk stress fractures typically require aggressive treatment such as nonweight-bearing immobilization coupled with therapy and often surgery.

Navicular stress fractures in identical twin runners: high-risk fractures require structured treatment.

Tarsal navicular fractures require an accurate and timely diagnosis to prevent costly and disabling complications. Diagnosis requires a thorough clinical evaluation that focuses on the patient's history, particularly his or her training regimen, and diet-as was the case with these 17-year-old girls. Plain radiography, ultrasound, bone scintigraphy, MRI, and CT help make a definitive diagnosis. Treatment of low-risk fractures involves relative rest and cessation of the precipitating activity. High-risk fractures often require non-weight-bearing immobilization, coupled with therapy, and may require surgery.

Synthetic and mechanistic studies of the retro-Claisen rearrangement. 4. An application to the total synthesis of (+)-Laurenyne.

[formula: see text] A novel asymmetric total synthesis of marine natural product (+)-Laurenyne has been achieved. The key elements of the strategy are the sequential metal ion-templated SN2' cyclization affording a highly functionalized chiral vinyl cyclobutane and a retro-Claisen rearrangement for the construction of an eight-membered ring ether.