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doi:10.4085/1062-6050-48.1.21 pmid:23672319 pmcid:PMC3554035 fatcat:3rzjjcoufjdrhcvkol3rciohf4
Fitting a log binomial model to binary outcome data makes it possible to estimate risk and relative risk for follow-up data, and prevalence and prevalence ratios for cross-sectional data. However, the fitting algorithm may fail to converge when the maximum likelihood solution is on the boundary of the allowable parameter space. Some authorities recommend switching to Poisson regression with robust standard errors to approximate the coefficients of the log binomial model in those circumstances.doi:10.1093/biomet/75.1.65 fatcat:6uz6oxaxlbaiplz4jqup24n4gu
more »... ose circumstances. This solves the problem of non-convergence, but results in errors in the coefficient estimates that may be substantial particularly when the maximum fitted value is large. The paradox is that the circumstances in which the modified Poisson approach is needed to overcome estimation problems are the same circumstances when the error in using it is greatest. We recommend that practitioners should be wary of using modified Poisson regression to approximate risk and relative risk.
When the upper extremity is injured, open kinetic chain (OKC) exercises are primarily used to increase strength and restore functional ability-the goals of rehabilitation. It is also imperative, however, that the receptors responsible for static and dynamic stabilization of the joint be trained. This can be done with closed kinetic chain (CKC) exercises. The purposes of this study were to investigate the effect of a 4-week CKC training program on the neuromuscular control of the upper extremitydoi:10.1123/jsr.8.3.184 fatcat:lqxcmsmwcrbh3kmjs2nv273qya
more »... the upper extremity and to determine whether there was a significant difference between skill-dominant limb and nondominant limb stability indices. Thirty-two physically active participants (14 men, 18 women) were tested on the FASTEX 4 weeks apart. The training group's scores significantly improved, whereas the control group's scores remained the same. It was concluded that the CKC training significantly improved the training group's ability to remain stable. The results suggest that CKC training can increase the accuracy of joint position sense because of increased stimulation of the mechanoreceptors. Rehabilitation of the injured upper extremity consists of many different phases and techniques. Researchers have demonstrated the functional implications of open kinetic chain (OKC) exercises for strengthening and sport-specific training of the shoulder complex (20,21). These exercises are essential for all overhead sports. It is only logical to train structures in the ways that they will be stressed during activity.
Adolescents may be particularly susceptible to malnutrition owing to the energy and nutrient costs of the pubertal growth spurt. Here, our aim is to compare differences in selected markers of nutritional status between adolescents and adults in rural Gambia. The Keneba Biobank collects cross-sectional data and samples for all consenting individuals resident in the West Kiang region of the Gambia. For this study, participants between the ages of 10 and 40 years were selected (n = 4201, femalesdoi:10.1111/nyas.13587 fatcat:qqxszbgpyvg6bongthm4prhl2a
more »... n = 4201, females 2447). Height, body mass index, body composition, hemoglobin concentration, fasting glucose concentration, and blood pressure were compared using linear regression models adjusting for age, parity, season of measurement, and residence, across three age groups: early adolescent (10-14.9 years), late adolescent (15-19.9 years), and adult (20-39.9 years). Adolescents, particularly early-adolescent girls and boys, were shorter, lighter, and leaner than adults. By late adolescence, differences were smaller, particularly in girls where, notably, the prevalence of overweight, hypertension, and impaired fasting glucose was low. Given the importance of maternal health for reproductive outcomes and intergenerational health, the results of the study, albeit with limited biomarkers available, indicate that adolescent girls are no more compromised than adult women or males from the same population.
E-mail: w.o.johnson@ lboro.ac.uk. ...doi:10.3945/ajcn.116.144196 pmid:28490512 pmcid:PMC5445671 fatcat:yrbjrhk27jgw3o6mqzzxzyw3wq
Context: Shoulder injuries are common in swimmers because of the demands of the sport. Muscle imbalances frequently exist due to the biomechanics of the sport, which predispose swimmers to injury. To date, an effective shoulder-injury-prevention program for competitive swimmers has not been established. Objective: To assess the effectiveness of a 6-wk strengthening and stretching intervention program on improving glenohumeral and scapular muscle strength and scapular kinematics in collegiatedoi:10.1123/jsr.21.3.253 pmid:22387875 fatcat:purbjtwgcfe4ba3zo2fxwvlbbe
more »... cs in collegiate swimmers. Design: Randomized control trial. Setting: University biomechanics research laboratory. Participants: Forty-four Division I collegiate swimmers. Interventions: The intervention program was completed 3 times per week for 6 wk. The program included strengthening exercises completed using resistance tubing-scapular retraction (Ts), scapular retraction with upward rotation (Ys), scapular retraction with downward rotation (Ws), shoulder flexion, low rows, throwing acceleration and deceleration, scapular punches, shoulder internal rotation at 90° abduction, and external rotation at 90° abduction-and 2 stretching exercises: corner stretch and sleeper stretch. Main Outcome Measurements: Scapular kinematics and glenohumeral and scapular muscle strength assessed preintervention and postintervention. Results: There were no significant between-groups differences in strength variables at pre/post tests, although shoulder-extension and internal-rotation strength significantly increased in all subjects regardless of group assignment. Scapular kinematic data revealed increased scapular internal rotation, protraction, and elevation in all subjects at posttesting but no significant effect of group on the individual kinematic variables. Conclusions: The current strengthening and stretching program was not effective in altering strength and scapular kinematic variables but may serve as a framework for future programs. Adding more stretching exercises, eliminating exercises that overlap with weight-room training and swim training, and timing of implementation may yield a more beneficial program for collegiate swimmers.
AAR reference angles included 30° internal rotation (30 IR), 30°e xternal rotation (30 ER), and 75° external rotation (75 ER). Three trials were performed at each reference angle. ...doi:10.1123/jsr.13.1.75 fatcat:ue6c2rzrgje25lc4glqqzinrfq
Dehydration and concussion are common in athletic performance. Some experts have speculated that dehydration may negatively influence performance on tests commonly used for concussion assessment. To determine how the signs and symptoms, neuropsychological performance, and postural stability are affected by dehydration. Repeated-measures design assessing subjects in the euhydrated and dehydrated conditions. Sports Medicine Research Laboratory. Twenty-four healthy, male recreational athletespmid:17597946 pmcid:PMC1896077 fatcat:zy4e2eak4zgyhfrw66pfw76xcu
more »... ional athletes participated in the study. Subjects participated in 2 counterbalanced sessions (euhydrated and dehydrated) separated by at least 7 days. Subjects were dehydrated using fluid restriction and an exercise task. No direct intervention was provided for the euhydrated condition. We used the Standardized Assessment of Concussion to test mental status, the Automated Neuropsychological Assessment Metrics (ANAM) to evaluate neuropsychological performance, the NeuroCom Sensory Organization Test and Balance Error Scoring System to test postural stability, the Graded Symptom Checklist to assess symptom presence and severity in our participants, and urine specific gravity and body mass to determine hydration status. No differences were noted for the Standardized Assessment of Concussion, total Balance Error Scoring System errors, composite Sensory Organization Test, and composite ANAM scores between conditions. Subjects in the dehydrated condition had significant deterioration in visual memory (t(23) = 2.130, P < .001) and fatigue measures (t(23) = -7.880, P < .001) as assessed by ANAM. The dehydrated condition resulted in subjects reporting a significantly higher number (t(23) = -8.585, P < .001) and severity (t(23) = -7.673, P < .001) of symptoms than the euhydrated subjects on the Graded Symptom Checklist. Our results suggest that moderate dehydration (-2.5 +/- 0.63%) significantly influenced the self-report of symptoms commonly associated with concussion. Dehydration resulted in a deterioration of visual memory and increases in the self-report of fatigue. Despite these findings, dehydration did not affect other neuropsychological and postural stability objective testing measures for concussion.
doi:10.1111/mcn.12367 pmid:27696720 pmcid:PMC5396370 fatcat:3z4czuyxmbgpjmnyl2dxrxhcym
Context: Female soccer athletes are at greater risk of anterior cruciate ligament (ACL) injury than males. Sex differences in muscle activation may contribute to the increased incidence of ACL injuries in female soccer athletes. Objective: To examine sex differences in lower extremity muscle activation between male and female soccer athletes at the National Collegiate Athletic Association Division I level during 2 side-step cutting maneuvers. Design: Cross-sectional with 1 between-subjectsdoi:10.4085/1062-6050-43.2.133 pmid:18345337 pmcid:PMC2267330 fatcat:ch2753t57zddbbgbhsln2xvteu
more »... tween-subjects factor (sex) and 2 within-subjects factors (cutting task and phase of contact). Setting: Sports medicine research laboratory. Patients or Other Participants: Twenty males (age ϭ 19.4 Ϯ 1.4 years, height ϭ 176.5 Ϯ 5.5 cm, mass ϭ 74.6 Ϯ 6.0 kg) and 20 females (age ϭ 19.8 Ϯ 1.1 years, height ϭ 165.7 Ϯ 4.3 cm, mass ϭ 62.2 Ϯ 7.2 kg). Intervention(s): In a single testing session, participants performed the running-approach side-step cut and the box-jump side-step cut tasks. Main Outcome Measure(s): Surface electromyographic ac-tivity of the rectus femoris, vastus lateralis, medial hamstrings, lateral hamstrings, gluteus medius, and gluteus maximus was recorded for each subject. Separate mixed-model, repeatedmeasures analysis of variance tests were used to compare the dependent variables across sex during the preparatory and loading contact phases of each cutting task. Results: Females displayed greater vastus lateralis activity and quadriceps to hamstrings coactivation ratios during the preparatory and loading phases, as well as greater gluteus medius activation during the preparatory phase only. No significant differences were noted between the sexes for muscle activation in the other muscles analyzed during each task. Conclusions: The quadriceps-dominant muscle activation pattern observed in recreationally active females is also present in female soccer athletes at the Division I level when compared with similarly trained male soccer athletes. The relationship between increased quadriceps activation and greater incidence of noncontact ACL injury in female soccer athletes versus males requires further study. Key Points • During a side-step cutting maneuver, female collegiate soccer athletes demonstrated more vastus lateralis activation than male collegiate soccer athletes did. • Female collegiate soccer athletes demonstrated larger quadriceps-to-hamstrings coactivation ratios than male collegiate soccer athletes, indicating that the females did not increase their hamstrings activation to compensate for increased quadriceps activation. • The sex differences in quadriceps activation and quadriceps-to-hamstrings coactivation ratios observed in recreational athletes were also present in highly trained and skilled collegiate soccer athletes. Ashley M. Hanson, MA, ATC, contributed to conception and design; acquisition and analysis and interpretation of the data; and drafting, critical revision, and final approval of the article.
High School RIO consists of a volunteer sample of HSs with 1 or more National Athletic Trainers' Association-affiliated ATs who have valid e-mail addresses. 12, 13 Although HS RIO has a national randomized ...doi:10.4085/1062-6050-229-18 pmid:31335177 pmcid:PMC6709758 fatcat:mijiihhxsre6riymgffvkcptye
Females with history of anterior cruciate ligament (ACL) injury and subsequent ligament reconstruction are at high risk for future ACL injury. Fatigue may influence the increased risk of future injury in females by altering lower extremity biomechanics and postural control. Hypothesis: Fatigue will promote lower extremity biomechanics and postural control deficits associated with ACL injury. Study Design: Descriptive laboratory study. Methods: Fourteen physically active females with ACLdoi:10.1177/1941738114530950 pmid:24982701 pmcid:PMC4065562 fatcat:qgry36ovjbefzhdwna2oa2iz7i
more »... es with ACL reconstruction (mean age, 19.64 ± 1.5 years; mean height, 163.52 ± 6.18 cm; mean mass, 62.6 ± 13.97 kg) volunteered for this study. Postural control and lower extremity biomechanics were assessed in the surgical limb during single-leg balance and jump-landing tasks before and after a fatigue protocol. Main outcome measures were 3-dimensional hip and knee joint angles at initial contact, peak angles, joint angular displacements and peak net joint moments, anterior tibial shear force, and vertical ground reaction force during the first 50% of the loading phase of the jump-landing task. During the single-leg stance task, the main outcome measure was center of pressure sway speed. Results: Initial contact hip flexion angle decreased (t = −2.82, P = 0.01; prefatigue, 40.98° ± 9.79°; postfatigue, 36.75° ± 8.61°) from pre-to postfatigue. Hip flexion displacement (t = 2.23, P = 0.04; prefatigue, 45.19° ± 14.1°; postfatigue, 47.48° ± 14.21°) and center of pressure sway speed (t = 3.95, P < 0.05; prefatigue, 5.18 ± 0.96 cm/s; postfatigue, 6.20 ± 1.72 cm/s) increased from pre-to postfatigue. There was a trending increase in hip flexion moment (t = 2.14, P = 0.05; prefatigue, 1.66 ± 0.68 Nm/kg/m; postfatigue, 1.91 ± 0.62 Nm/kg/m) from pre-to postfatigue. Conclusion: Fatigue may induce lower extremity biomechanics and postural control deficits that may be associated with ACL injury in physically active females with ACL reconstruction. Clinical Relevance: Rehabilitation and maintenance programs should incorporate activities that aim to improve muscular endurance and improve the neuromuscular system's tolerance to fatiguing exercise in efforts to maintain stability and safe landing technique during subsequent physical activity.
Participants were recruited through mass e-mails, flyers placed around campus, exercise and sports science classes, and the intercollegiate and club sporting groups. ...doi:10.4085/1062-6050-48.1.13 pmid:23672321 pmcid:PMC3554027 fatcat:k535up7acvc5bbi6laecojc2ra
Journal of Nutrition
The WHO recommends exclusive breastfeeding (EBF) for the first 6 mo of life. Objective: The objective of this study was to assess the benefit of EBF to age 6 mo on growth in a large sample of rural Gambian infants at high risk of undernutrition. Methods: Infants with growth monitoring from birth to 2 y of age (n = 756) from the ENID (Early Nutrition and Immune Development) trial were categorized as exclusively breastfed if only breast milk and no other liquids or foods were given. EBF statusdoi:10.3945/jn.116.241737 pmid:28003540 pmcid:PMC5265696 fatcat:wwxoojrcmjd5jelubjabjueagi
more »... iven. EBF status was entered into confounder-adjusted multilevel models to test associations with growth trajectories by using >11,000 weight-for-age (WAZ), length-for-age (LAZ), and weight-for-length (WLZ) z score observations. Results: Thirty-two percent of infants were exclusively breastfed to age 6 mo. The mean age of discontinuation of EBF was 5.2 mo, and growth faltering started at ;3.5 mo of age. Some evidence for a difference in WAZ and WHZ was found between infants who were exclusively breastfed to age 6 mo (EBF-6) and those who were not (nEBF-6), at 6 and 12 mo of age, with EBF-6 children having a higher mean z score. The differences in z scores between the 2 groups were small in magnitude (at 6 mo of age: 0.147 WAZ; 95% CI: 20.001, 0.293 WAZ; 0.189 WHZ; 95% CI: 0.038, 0.341 WHZ). No evidence for a difference between EBF-6 and nEBF-6 infants was observed for LAZ at any time point (6, 12, and 24 mo of age). Furthermore, a higher mean WLZ at 3 mo of age was associated with a subsequent higher mean age at discontinuation of EBF, which implied reverse causality in this setting (coefficient: 0.060; 95% CI: 0.008, 0.120). Conclusion: This study suggests that EBF to age 6 mo has limited benefit to the growth of rural Gambian infants. This trial was registered at http://www.isrctn.com as ISRCTN49285450.
Context: Recent evidence has revealed deficiencies in the ability to divide attention after concussion. Objective: To examine the effects of a single vs a dual task on cognition and balance in healthy subjects and to examine reliability of 2 dual-task paradigms while examining the overall feasibility of the tasks. Design: Pretest-posttest experimental design. Setting: Sports medicine research laboratory. Patients: 30 healthy, recreationally active college students. Intervention: Subjectsdoi:10.1123/jsr.20.3.296 pmid:21828382 fatcat:slmwotri35d75ciqgfk7qzxywu
more »... on: Subjects performed balance and cognitive tasks under the single-and dual-task conditions during 2 test sessions 14 d apart. Main Outcome Measures: The procedural reaction-time (PRT) test of the Automated Neuropsychological Assessment Metrics (eyes-closed tasks) and an adapted Procedural Auditory Task (PAT; eyes-open tasks) were used to assess cognition. The NeuroCom Sensory Organization Test (SOT) and the Balance Error Scoring System (BESS) were used to assess balance performance. Five 2-way, within-subject ANOVAs and a paired-samples t test were used to analyze the data. ICCs were used to assess reliability across 2 test sessions. Results: On the SOT, performance significantly improved between test sessions (F 1,29 = 35.695, P < .001) and from the single to the dual task (F 1,29 = 9.604, P = .004). On the PRT, performance significantly improved between test sessions (F 1,29 = 57.252, P < .001) and from the single to the dual task (F 1,29 = 7.673, P = .010). No differences were seen on the BESS and the PAT. Reliability across test sessions ranged from moderate to poor for outcome measure. Conclusions: The BESS appears to be a more reliable and functional tool in dual-task conditions as a result of its increased reliability and clinical applicability. In addition, the BESS is more readily available to clinicians than the SOT.
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