A Model for Causality of Pitching-related Overuse Injuries in Women's Fastpitch Softball.

Fastpitch softball is a popular women's sport, and athletes, particularly pitchers, are at high risk for overuse injury. Softball-related injury rates are low; however, the prevalence of overuse injuries is high. Injuries at the high school and collegiate levels occur early in the season, and approximately 50% of shoulder and elbow injuries in softball are attributable to overuse. Survey research showed 77% of high school pitchers pitch with pain, and 73% of collegiate pitchers reported an overuse injury in the previous season. Modifiable and non-modifiable intrinsic and extrinsic risk factors contribute to injury risk in a model that can be used in history taking, clinical examination, and management of softball-related injuries. In this manuscript, we present a scoping review of fastpitch softball injury research by competitive levels from 1990 to present. We also introduce a model for overuse injury causality in this athlete population. With this information, clinicians will be able to identify risk factors related to injury in softball pitchers. More research is needed to make evidence-based recommendations for injury prevention in this athlete population.

Evaluation of Hip Characteristics in Baseball and Softball Athletes with and Without Throwing Arm Pain.

During throwing, the lower extremity assists in the generation and transfer of momentum. Lower extremity stability assists in this transfer by providing a base for distal mobility of the arm segments. This study aimed to determine differences between hip rotational range of motion and strength based on the presence of throwing-arm pain (yes/no) and throwing sport (baseball/softball). We hypothesized those experiencing pain would display decreases in hip range of motion and strength, and that softball players would display greater range of motion than baseball, but less strength based on sex-specific characteristics. Forty-four baseball (13±2 years, 165.2±13.0 cm, 58.5±13.4 kg) and 50 softball players (13±2 years, 160.9±11.2 cm, 62.7±17.9 kg) participated. Multivariate analysis of variance tests (2×2) determined differences in bilateral hip range of motion, total arc of motion, and strength between pain status and sport. There were no significant interactions (>0.05) for pain status and sport on hip range of motion, total arc of motion, and strength. Furthermore, no significant main effects (>0.05) were found for pain status or sport alone on range of motion or strength. Future work should be directed at explaining the effects of hip characteristics on the throwing motion and how it equates to throwing-arm health.

Treatment patterns of in-patient spasticity medication use after traumatic spinal cord injury: a prospective cohort study.

STUDY DESIGN: Prospective cohort study using the Rick Hansen SCI Registry (RHSCIR) and retrospective medical chart review. OBJECTIVE: To describe treatment patterns of in-patient anti-spasticity medication use following traumatic spinal cord injury (SCI) in acute and rehabilitation hospital settings in British Columbia, Canada. SETTING: Quaternary trauma center, rehabilitation center. METHODS: Individuals with traumatic SCI between 2005 and 2014 enrolled in the Vancouver RHSCIR site (N = 917) were eligible for inclusion. Oral and injectable anti-spasticity medication use were the main outcome measures. RESULTS: In 769 participants, higher neurological level and injury severity were associated with in-patient anti-spasticity medication use (p < 0.001 for both). Of individuals with cervical and thoracic injuries (n = 589), 37% were prescribed anti-spasticity medication during hospital admission. Baclofen was the most commonly used first line oral therapy. Mean (SD) and median time from injury to Baclofen initiation was 70 (69) and 50 days, respectively. The probability of having initiated an in-patient anti-spasticity medication was 55% (95% CI (49, 60)) for individuals 6 months post-injury, and 71% (95% CI (62, 79)) for individuals 12 months post-injury. At community discharge, the prevalence of oral and injectable anti-spasticity medication use was 26 and 5%. Practice patterns of anti-spasticity medication use (2005-2009 vs. 2010-2014) have not changed significantly over time. CONCLUSIONS: This is the first large prospective cohort study of in-patient anti-spasticity medication use following traumatic SCI. Results from our study inform clinicians and individuals of "real world" anti-spasticity medication use among individuals with traumatic SCI and may help guide care for this population in the community.

Prevalence and Effect of Problematic Spasticity After Traumatic Spinal Cord Injury.

OBJECTIVE: To evaluate the prevalence and effect of spasticity after traumatic spinal cord injury (SCI). DESIGN: Prospective cohort study of the Rick Hansen Spinal Cord Injury Registry (RHSCIR) and retrospective review of inpatient medical charts. SETTING: Quaternary trauma center, rehabilitation center, and community settings. PARTICIPANTS: Individuals (N=860) with a traumatic SCI between March 1, 2005, and March 31, 2014, prospectively enrolled in the Vancouver site RHSCIR were eligible for inclusion. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Questionnaires (Penn Spasm Frequency Scale, Spinal Cord Injury Health Questionnaire) and antispasticity medication use. RESULTS: In 465 patients, the prevalence of spasticity at community discharge was 65%, and the prevalence of problematic spasticity (defined as discharged on antispasticity medication) was 35%. Problematic spasticity was associated with cervicothoracic neurologic level and injury severity (P<.001). In community follow-up, the prevalence of patients reporting any spasticity treatment (ie, problematic spasticity) was 35% at 1 year, 41% at 2 years, and 31% at 5 years postinjury. Interference with function caused by spasticity was reported by 27% of patients at 1 year, 25% at 2 years, and 20% at 5 years postinjury. Patients with American Spinal Injury Association Impairment Scale grade C injuries had the highest prevalence of ongoing spasticity treatment and functional limitation. CONCLUSIONS: Spasticity is a highly prevalent secondary consequence of SCI, particularly in patients with severe motor incomplete cervicothoracic injuries. It is problematic in one third of all patients with SCI up to 5 years postinjury. One in 5 patients will have ongoing functional limitations related to spasticity, highlighting the importance of close community follow-up and the need for further research into spasticity management strategies.

Exercise behaviour and attitudes among fourth-year medical students at the University of British Columbia.

OBJECTIVE: To describe the physical activity (PA) levels and counseling attitudes of Canadian undergraduate medical students. DESIGN: Online or paper survey. SETTING: The University of British Columbia (UBC). PARTICIPANTS: Fourth-year medical students at UBC from 2007 to 2010. MAIN OUTCOME MEASURES: Physical activity levels, relationship between exercise behaviour and attitudes toward counseling, and student perception of training in the area of exercise prescription. RESULTS: A total of 546 out of 883 students participated in the survey (62% response rate). Sixty-four percent of students met the Canadian Society for Exercise Physiology 2011 recommendations for PA. Attitudes toward healthy living were related to PA levels, but the rate of counseling patients about exercise was not; however, students who engaged in more strenuous PA were more likely to perceive exercise counseling as being highly relevant to future clinical practice (P = .018). Overall, 69% of students perceived exercise counseling to be highly relevant to clinical practice, but 86% thought that their training in this area was less than extensive. CONCLUSION: Fourth-year UBC medical students engage in more strenuous PA than average age-matched Canadians, which affects their attitudes toward perceived future counseling practices. Encouraging more student participation in strenuous PA and encouraging academic training in the area of exercise counseling might be important next steps in preparing future physicians to effectively prescribe exercise to their patients.

Early predictors of developing problematic spasticity following traumatic spinal cord injury: A prospective cohort study.

Objective: To identify early predictors and develop reliable, validated prediction models for development of problematic spasticity after traumatic spinal cord injury (SCI).Design: Prospective cohort study of the Rick Hansen Spinal Cord Injury Registry (RHSCIR), retrospective review of inpatient medical charts.Setting: Quaternary trauma center, rehabilitation center, community settings.Participants: Individuals with traumatic SCI between March 1, 2005, and March 31, 2014, prospectively enrolled in the Vancouver site RHSCIR.Interventions: None.Main Outcome Measure: Spasticity limiting function or requiring treatment (problematic spasticity) on the Spinal Cord Injury Health Questionnaire.Results: In 350 patients, variables documented during hospitalization that predicted the development of problematic spasticity up to 5 years post-injury included: initial Glasgow Coma Scale; age at time of injury; admission to rehabilitation center; community discharge anti-spasticity medication prescription, neurological status, Penn Spasm Frequency Scale, and pain interference with quality of life, sleep, activities; greater change in AIS motor scores between admission and discharge. The predictive models had area under the receiver operating characteristic curve of 0.80 (95% CI 0.75, 0.85) in the development set (N = 244) and 0.84 (95% CI 0.74, 0.92) in the validation set (N = 106) for spasticity limiting function and 0.81 (95% CI 0.76, 0.85) in the development set and 0.85 (95% CI 0.77, 0.92) in the validation set for spasticity requiring treatment.Conclusions: Our prediction models provide an early prognosis of risk of developing problematic spasticity after traumatic SCI, which can be used to improve clinical spasticity management and assist research (e.g. risk stratification in interventional trials).

Upper Extremity Functional Status of Female Youth Softball Pitchers Using the Kerlan-Jobe Orthopaedic Clinic Questionnaire.

BACKGROUND: Softball is a popular sport with a high incidence of upper extremity injuries. The Kerlan-Jobe Orthopaedic Clinic (KJOC) questionnaire is a validated performance and functional assessment tool used in overhead athletes. Upper extremity pain patterns and baseline KJOC scores have not been reported for active female youth softball pitchers. PURPOSE/HYPOTHESIS: The purpose of this study was to establish the prevalence of upper extremity pain and its effect in female youth softball pitchers over a competitive season. We hypothesized that participants who missed time due to injury in the past year would have lower KJOC scores. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Fifty-three female softball pitchers aged 12 to 18 years were recruited from softball clinics in Vancouver, British Columbia, Canada. All participants self-identified as a pitcher on a competitive travel team. Participants were administered the KJOC questionnaire before and during the playing season. Missed time due to injury in the past year, current pain patterns, and KJOC scores were primary outcomes. RESULTS: The mean (±SD) preseason KJOC score was 87.2 ± 10.6. In the preseason, 22.6% of pitchers reported playing with arm trouble, and 32.1% missed time due to injury in the past year. The mean KJOC score for pitchers reporting a previous injury (n = 17) was significantly lower compared with those without an injury (n = 36) (79.5 ± 13.8 vs 90.9 ± 6.2, respectively; P = .02). The posterior shoulder was the most commonly reported pain location. For the cohort completing the questionnaire both before and during the playing season (n = 35), mean KJOC scores did not change significantly over the playing season (P = .64). Lower preseason KJOC scores were significantly related to the in-season injury risk (P = .016). Pitchers with a preseason score of less than 90 had a 3.5 (95% CI, 1.1-11.2) times greater risk of reporting an in-season injury. CONCLUSION: Female youth softball pitchers have a high baseline functional status. However, 1 in 3 pitchers reported missed time due to injury in the previous year, and shoulder pain was more prevalent than elbow pain. The KJOC questionnaire can be used by coaches, researchers, and clinicians to identify youth softball pitchers at risk for injuries who may benefit from interventions.

Thyroid hormone signaling in vivo requires a balance between coactivators and corepressors.

Resistance to thyroid hormone (RTH), a human syndrome, is characterized by high thyroid hormone (TH) and thyroid-stimulating hormone (TSH) levels. Mice with mutations in the thyroid hormone receptor beta (TRß) gene that cannot bind steroid receptor coactivator 1 (SRC-1) and Src-1(-/-) mice both have phenotypes similar to that of RTH. Conversely, mice expressing a mutant nuclear corepressor 1 (Ncor1) allele that cannot interact with TRß, termed NCoRΔID, have low TH levels and normal TSH. We hypothesized that Src-1(-/-) mice have RTH due to unopposed corepressor action. To test this, we crossed NCoRΔID and Src-1(-/-) mice to create mice deficient for coregulator action in all cell types. Remarkably, NCoR(ΔID/ΔID) Src-1(-/-) mice have normal TH and TSH levels and are triiodothryonine (T(3)) sensitive at the level of the pituitary. Although absence of SRC-1 prevented T(3) activation of key hepatic gene targets, NCoR(ΔID/ΔID) Src-1(-/-) mice reacquired hepatic T(3) sensitivity. Using in vivo chromatin immunoprecipitation assays (ChIP) for the related coactivator SRC-2, we found enhanced SRC-2 recruitment to TR-binding regions of genes in NCoR(ΔID/ΔID) Src-1(-/-) mice, suggesting that SRC-2 is responsible for T(3) sensitivity in the absence of NCoR1 and SRC-1. Thus, T(3) targets require a critical balance between NCoR1 and SRC-1. Furthermore, replacement of NCoR1 with NCoRΔID corrects RTH in Src-1(-/-) mice through increased SRC-2 recruitment to T(3) target genes.

Hepatic nuclear corepressor 1 regulates cholesterol absorption through a TRß1-governed pathway.

Transcriptional coregulators are important components of nuclear receptor (NR) signaling machinery and provide additional mechanisms for modulation of NR activity. Expression of a mutated nuclear corepressor 1 (NCoR1) that lacks 2 NR interacting domains (NCoRΔID) in the liver leads to elevated expression of genes regulated by thyroid hormone receptor (TR) and liver X receptor (LXR), both of which control hepatic cholesterol metabolism. Here, we demonstrate that expression of NCoRΔID in mouse liver improves dietary cholesterol tolerance in an LXRα-independent manner. NCoRΔID-associated cholesterol tolerance was primarily due to diminished intestinal cholesterol absorption as the result of changes in the composition and hydrophobicity of the bile salt pool. Alterations of the bile salt pool were mediated by increased expression of genes encoding the bile acid metabolism enzymes CYP27A1 and CYP3A11 as well as canalicular bile salt pump ABCB11. We have determined that these genes are regulated by thyroid hormone and that TRß1 is recruited to their regulatory regions. Together, these data indicate that interactions between NCoR1 and TR control a specific pathway involved in regulation of cholesterol metabolism and clearance.

The nuclear receptor corepressor (NCoR) controls thyroid hormone sensitivity and the set point of the hypothalamic-pituitary-thyroid axis.

The role of nuclear receptor corepressor (NCoR) in thyroid hormone (TH) action has been difficult to discern because global deletion of NCoR is embryonic lethal. To circumvent this, we developed mice that globally express a modified NCoR protein (NCoRΔID) that cannot be recruited to the thyroid hormone receptor (TR). These mice present with low serum T(4) and T(3) concentrations accompanied by normal TSH levels, suggesting central hypothyroidism. However, they grow normally and have increased energy expenditure and normal or elevated TR-target gene expression across multiple tissues, which is not consistent with hypothyroidism. Although these findings imply an increased peripheral sensitivity to TH, the hypothalamic-pituitary-thyroid axis is not more sensitive to acute changes in TH concentrations but appears to be reset to recognize the reduced TH levels as normal. Furthermore, the thyroid gland itself, although normal in size, has reduced levels of nonthyroglobulin-bound T(4) and T(3) and demonstrates decreased responsiveness to TSH. Thus, the TR-NCoR interaction controls systemic TH sensitivity as well as the set point at all levels of the hypothalamic-pituitary-thyroid axis. These findings suggest that NCoR levels could alter cell-specific TH action that would not be reflected by the serum TSH.

The effect of carbohydrate availability following exercise on whole-body insulin action.

One bout of exercise enhances insulin-stimulated glucose uptake (insulin action), but the effect is blunted by consumption of carbohydrate-containing food after exercise. The independent roles of energy and carbohydrate in mediating post-exercise insulin action have not been systematically evaluated in humans. The purpose of this study was to determine if varying carbohydrate availability, with energy intake held constant, mediates post-exercise insulin action. Ten young (21 +/- 2 y, overweight (body fat 37% +/- 3%) men and women completed 3 conditions in random order: (i) no-exercise (BASE), (ii) exercise with energy balance but carbohydrate deficit (C-DEF), and (iii) exercise with energy and carbohydrate balance (C-BAL). In the exercise conditions, subjects expended 30% of total daily energy expenditure on a cycle ergometer at 70% VO2 peak. Following exercise, subjects consumed a meal that replaced expended energy (~3000 kJ) and was either balanced (intake = expenditure) or deficient (-100 g) in carbohydrate. Twelve hours later, insulin action was measured by continuous infusion of glucose with stable isotope tracer (CIG-SIT). Changes in insulin action were evaluated using a one-way ANOVA with repeated measures. During CIG-SIT, non-oxidative glucose disposal (i.e., glucose storage) was higher in C-DEF than in BASE (27.2 +/- 3.2 vs. 16.9 +/- 3.5 micromol.L-1.kg-1.min-1, p < 0.05). Conversely, glucose oxidation was lower in C-DEF (8.6 +/- 1.3 micromol.L-1.kg-1.min-1) compared with C-BAL (12.2 +/- 1.2 micromol.L-1.kg-1.min-1), and BASE (17.1 +/- 2.2 micromol.L-1.kg-1.min-1), p < 0.05). Fasting fat oxidation was higher in C-DEF than in BASE (109.8 +/- 10.5 vs. 80.7 +/- 9.6 mg.min-1, p < 0.05). In C-DEF, enhanced insulin action was correlated with the magnitude of the carbohydrate deficit (r = 0.82, p < 0.01). Following exercise, re-feeding expended energy, but not carbohydrate, increased fasting fat oxidation, and shifted insulin-mediated glucose disposal toward increased storage and away from oxidation.

Effect of timing of energy and carbohydrate replacement on post-exercise insulin action.

The nutritional environment surrounding an exercise bout modulates post-exercise insulin action. The purpose of this study was to determine how timing energy and carbohydrate replacement proximate to an exercise bout influences exercise-enhanced insulin action. To create an appropriate baseline, sensitivity to insulin was reduced in 9 healthy young men (n=6) and women (n=3) by 2 days of energy surplus and detraining. Then, insulin action (glucose uptake per unit plasma insulin) was assessed by stable isotope dilution during a continuous glucose infusion 12 h after a standardized meal under 4 conditions. In 3 conditions, the meal replaced the energy and carbohydrate expended during an exercise bout (62.9+/-2.8 min cycle ergometry at 65% VO2 peak followed by ten 30 s sprints). The meal was given before (Pre), immediately after (ImmPost), or 3 h after exercise (Delay). The 4th condition was a no-exercise control (Control). Data were analyzed using linear mixed-effects models with planned contrasts. Relative to Control, insulin action increased by 22% in Pre (p=0.05), 44% in ImmPost (p<0.01), and 19% in Delay (p=0.09). Non-oxidative disposal was higher, and oxidative disposal was lower in ImmPost relative to Control and Pre (p<0.05). Hepatic glucose production was suppressed by the infusion to a greater extent in Pre and Delay (76.9%+/-8.8% and 81.2%+/-4.7%) compared with ImmPost (64.7%+/-10.0%). A bout of exercise enhances insulin action even when expended energy and carbohydrate are replaced. Further, timing of energy and carbohydrate consumption subtly modulates the effectiveness of exercise to enhance insulin action.