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Female athletes suffer painful, costly, and career-limiting non-contact anterior cruciate ligament (ACL) injuries more often than males. Previous research suggests that pubertal neuromusculoskeletal development contributes to this sex-bias, but the manner in which variation in pubertal development affects injury risk within females is poorly understood. Age at menarche is a variable, significant pubertal developmental event, signaling the onset of estrogen cycling and affecting musculoskeletal development. Earlier menarche may increase injury risk, possibly by increasing anterior knee laxity through prolonged estrogen exposure. The purpose of this case-control study was to test the primary hypothesis that collegiate athletes with previous ACL injuries have earlier age at menarche than their uninjured peers, and to test the secondary hypothesis that earlier menarche is related to greater anterior knee laxity in injured and uninjured athletes. The study sample consisted of female NCAA Division-I varsity athletes (N=14 injured, N=120 uninjured). Outcome measures included: menstrual history and ACL injury details (injury age, activity at time of injury, contact vs. non-contact), assessed by questionnaire; and anterior knee laxity assessed by KT-1000 arthrometer. Correlation, t-tests, and regression analysis were used to test for associations between age at menarche, injury incidence, and knee laxity. Fourteen athletes reported ≥1 non-contact ACL injury, and had significantly earlier menarche than uninjured athletes (12.6±1.3 y vs. 13.4±1.4 y; P=0.05). Earlier menarche also significantly predicted injury status (Wald c2=7.43; Pb=-1.02±0.37; OR=0.36; 95% CI:0.17-0.75), but was not correlated with anterior knee laxity. Within injured athletes, however, laxity in the unaffected knee was significantly related to time since menarche (r2=0.79, Pr2=0.72, P

Purpose: Physical activity and exercise are critical for older adults' physical and mental health. The purpose of this qualitative study was to richly capture the motivators of and barriers to engaging in physical activity in previously inactive older adults who participated in a threearm randomized controlled trial (RCT) of eight-week group exercise interventions. Methods: We conducted a qualitative content analysis of individual interviews with fifteen participants--five from each study arm: strength training, walking, and inactive control. Participants included nine females and six males ranging from 60 to 86 years of age. Results: Key motivators of physical activity included perceived improvements in physical and mental health, positive social influences, observed health deterioration in others, and the desire to spend time with and take care of family members. Barriers to physical activity included existing health conditions, fear of getting hurt, negative social influences, perceived lack of time and motivation, inconvenient times and locations, and monetary cost. Conclusions: Our findings add to the body of literature identifying factors that motivate and stand in the way of older adults' engagement in physical activity. These factors influence older adults' self-efficacy and should be incorporated into the design of new and existing programs to encourage initiation and maintenance of physical activity. [ABSTRACT FROM AUTHOR]

Older adults are challenged with aging-related declines in skeletal muscle mass and function. Although exercise interventions of longer duration typically yield larger changes, shorter-term interventions may kick-start positive effects, allowing participants to begin engaging in more activity. This study aimed to determine whether 8 weeks of a resistance training program (Stay Strong, Stay Healthy [SSSH]) improved dynamic muscle strength, balance, flexibility, and sleep. Inactive adults aged ≥60 years were randomized into SSSH (n = 15), walking (WALK; n = 17), or control (CON; n = 14) groups. The SSSH and WALK groups met 2 times per week for 60 min. The participants completed pre/post general health, activity, and sleep questionnaires; DXA scans; and functional tasks. One-way repeated-measures multivariate analysis of variance was used to determine interactions and decomposed using repeated-measures analysis of variance. SSSH improved sit-to-stand performance, back scratch distance, and sleep quality and reported more auxiliary physical activity than WALK or CON (p <.05). Resistance training interventions in sedentary older adults can improve physical function and encourage additional activity in 8 weeks. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the study was to evaluate the effect of skeletal age and lesion size, location, and grade on the success of nonoperative treatment for juvenile osteochondritis dissecans (OCD). It is hypothesized that skeletal maturity, including a combination of maturation phenotypes, correlates with nonoperative lesion healing. Methods: The clinical and radiographic data on 52 patients aged 7–20 years treated for OCD of the distal femur between 2010 and 2019 were retrospectively reviewed. Knee radiographs were assessed for number of lesions present and lesion location, size, and stage. Assessments of skeletal maturation were performed on all antero-posterior knee radiographs using the Roche, Wainer, and Thissen (RWT) method. Patients were categorized as healed if they demonstrated no pain on clinical examination. The relationship between skeletal maturity and nonoperative lesion healing was determined using Spearman rank correlations on available variables. Results: Neither chronological nor skeletal age was associated with surgical status (Rho = 0.03, n.s., and Rho = 0.13, n.s., respectively) or the healing status of nonoperatively treated OCD lesions (Rho = 0.44, n.s., and Rho = 0.03, n.s., respectively). Epiphyseal fusion status of the distal femoral physis was moderately correlated with nonoperative healing, but was not statistically significant (lateral femoral physis: Rho = 0.43, p = 0.05; medial femoral physis: Rho = 0.43, n.s.). Lesion length correlated with surgical status (Rho = − 0.38, p = 0.009). Conclusion: The extent of fusion of the distal femoral physis (multi-stage grading) may be more strongly correlated with nonoperative healing than other markers of skeletal maturity or chronological age. Clinicians can use this as an additional radiographic sign when considering nonoperative treatment for juvenile OCD lesions in the distal femur. OCD lesion length and physeal fusion status appear to be more important for healing than patient age. [ABSTRACT FROM AUTHOR]

Introduction: Puberty substantially alters the body's mechanical properties, neuromuscular control, and sex differences therein, likely contributing to increased, sex‐biased knee injury risk during adolescence. Female adolescents have higher risk for knee injuries than male adolescents of similar age engaging in similar physical activities, and much research has investigated sex differences in mechanical risk factors. However, few studies address the considerable variation in pubertal growth (timing, pace), knee mechanics, and injury susceptibility within sexes, or the impact of such growth variation on mechanical injury risk. Objectives: The present study tested for effects of variation in pubertal growth on established mechanical knee injury risk factors, examining relationships between and within sexes. Methods: Pubertal growth indices describing variation in the timing and rate of pubertal growth were developed using principal component analysis and auxological data from serial stature measurements. Linear mixed models were applied to evaluate relationships between these indices and knee mechanics during walking in a sample of adolescents. Results: Later developing female adolescents with slower pubertal growth had higher extension moments throughout stance, whereas earlier developers had higher valgus knee angles and moments. In male adolescents, faster and later growth were related to higher extension moments throughout gait. In both sexes, faster growers had higher internal rotation moments at foot‐strike. Conclusions: Pubertal growth variation has important effects on mechanical knee injury risk in adolescence, affecting females and males differently. Earlier developing females exhibit greater injury risk via frontal plane factors, whereas later/faster developing males have elevated risk via sagittal plane mechanisms. [ABSTRACT FROM AUTHOR]

Numerous studies have detected significant contributions of genes to variation in development, size, and shape of craniofacial traits in a number of vertebrate taxa. This study examines 43 quantitative traits derived from lateral cephalographs of 830 baboons (Papio hamadryas) from the pedigreed population housed at the Southwest National Primate Research Center. Quantitative genetic analyses were conducted using the SOLAR analytic platform, a maximum-likelihood variance components method that incorporates all familial information for parameter estimation. Heritability estimates were significant and of moderate to high magnitude for all craniofacial traits. Additionally, 14 significant quantitative trait loci (QTL) were identified for 12 traits from the three developmental components (basicranium, splanchnocranium, and neurocranium) of the craniofacial complex. These QTL were found on baboon chromosomes (and human orthologs) PHA1 (HSA1), PHA 2 (HSA3), PHA4 (HSA6), PHA11 (HSA12), PHA13 (HSA2), PHA16 (HSA17), and PHA17 (HSA13) (PHA, P. hamadryas; HSA, Homo sapiens). This study of the genetic architecture of the craniofacial complex in baboons provides the groundwork needed to establish the baboon as an animal model for the study of genetic and nongenetic influences on craniofacial variation.