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Article in press
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Agreement and Validity of Existing Anthropometric Calibration Models to Estimate Whole Body Density in Male Professional Football Players
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Abstract [+]
Introduction
To date no calibration models exist to estimate whole body density (Db) of professional footballers, as such the development of practical anthropometric calibration models to make sound body composition judgements is imperative. The aim of this study was to investigate the agreement and validity of estimating Db from 15 existing calibration models through comparison to a criterion method of hydrostatic weighing (HW) in male professional footballers.
Materials and Methods
Data were gathered from a total of n=206 professional football participants (x±s; age=24.1±5.4-years, body mass=78.8±8.4 kg, stature=180.1±7.0 cm, Db 1.075±0.01 g.ml-1). Bland and Altman limits of agreement (LoA) approaches were used to determine bias and random variation derived from the calibration models.
Results
Bias and random errors for the published calibration models ranged from -0.005 to +0.015 g.ml-1 and 1.012 to 1.090 g.ml-1 respectively. A priori criterion (±3.8% p=<0.05 (g.ml-1)) was set as acceptable limits for the LoA method of which 13 calibration models found that (on average) estimated Db derived from HW was greater than Db derived from the models. Discussion A rank order of LoA identified the best model to use, however, LoA were not narrow enough for measurements to be of practical use and in most instances, selected models are not appropriate for estimating Db in male professional footballers. Keywords Whole body density; Calibration models; Anthropometry; Professional football players; Agreement; Validity.
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Physical Activity Motives in the Exercise and Self-Esteem Relationship
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Aims and Objectives
The purpose of this investigation was to extend research examining physical and social influences in the exercise/self-esteem relationship by investigating the moderating role of physical activity motives. Research reveals multiple motives for exercise participation beyond physical health enhancement. It is thought that these motives may play an important role in the relationship between exercise and self-esteem. Previous research has established the contribution of the physical self-system in the relationship. Furthermore, research examining the contribution social self-system has shown promise, yet the mechanisms operating in the relationship are less clear. It was hypothesized that motivation for physical activity participation may be such a mechanism.
Results
A population of 147 undergraduates completed assessments of physical activity participation, motives for physical activity, and physical, social and global self-perceptions. As expected, physical activity participation influenced self-esteem through both physical and social systems. Additionally, socially motivated exercisers exhibited greater self-esteem enhancement through the social as opposed to the physical self-system.
Conclusion
The hypothesis that physical activity motives would play an important role in determining the pathway through which physical activity participation influences self-esteem was partially supported. Results showed that those who reported social motives for physical activity showed greater enhancement in self-esteem through the social self-system, while physical motives did not serve a moderating role. The findings from the present investigation are important not only from the perspective of self-esteem theory but also with regard to the numerous practical implications of the results. The findings confirm that the relationship between exercise participation and self-esteem is more complex than previously thought in that physical activity participation influences self-esteem through multiple pathways. What remains to be investigated is how to best flesh out which pathway is more meaningful to the exerciser and then how to best serve the interests of the exerciser with the ultimate goal of enhancing self-esteem.
Keywords
Self-esteem, Physical activity, Exercise, Self-concept, Motives.
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Current Issue
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Comparison of Anthropometric Equations and Dual X-ray Absorptiometry to Determine Body Composition in Active Breast Cancer Survivors
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Objective
The purpose of this study was to 1) compare the body composition values of an active group of breast cancer survivors (BCS) determined by dual X-ray absorptiometry (DXA) and anthropometry, and 2) compare the bone mineral density of the upper thoracic region to assess the effect of tumor burden on bone health.
Design and Methods
Forty (n=40) breast cancer survivors from a local competitive Dragon Boat Team were measured as part of team assessments. ANOVA with Dunn’s post-hoc testing was used to compare results of DXA, body density, and body composition estimated from anthropometry. Bland-Altman testing and correlational analysis were calculated.
Results
Percentage of fat measure by DXA was significantly higher than values used to estimate body fat from skinfold measures or from body density equations (DXA 41.1±6.0% vs. 3-site skinfolds 28.8±4.9%, 4-site skinfolds, 22.1±4.1%, skinfold and body density, 31.8±9.4%, respectively, p<0.05). Post-hoc testing revealed that all values were significantly different and the strongest correlation with DXA was skinfolds at three sites was r=0.81. Regional (upper thoracic) bone mineral density was not significantly different based on tumor side diagnosis (breast cancer diagnosis side versus healthy, 0.971±0.198 vs. 0.988±0.190 gm*cc-1). Anthropometry and bilateral bone mineral density characteristics are presented to serve as a comparative sample of BCS for future studies. Conclusion As body composition is an important factor in long-term cancer survivorship, we found the use of skinfold measures inadequate to accurately determine percentage of fat in this group of active female BCS. As a result, recommendations aimed at achieving an ideal body composition based solely on anthropometry would have grossly underestimated fat mass, which may lead to overall clinically poorer outcomes. Keywords Breast cancer; Body composition; Percentage fat; Bone mineral density.
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Hyperbaric Oxygen Attenuates Aortic Vasoconstriction after Simulated Microgravity in Rats
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Background
The hindlimb suspended (HLS) rat model has been used in land-based research to evaluate effects of simulated microgravity. Previous research demonstrated that 2-4 weeks of HLS reduced vasoconstrictive responses of aortic, mesenteric, and femoral arterial rings to phenylephrine (PHE) while acute exposure to hyperoxia amplified constrictive responses to PHE. The purpose of this study was to determine if hyperbaric oxygen treatment (HBO) during HLS would reverse the attenuation of the vasoconstrictive response.
Methods
Five-month-old male Sprague Dawley rats were randomly divided into aging controls (AC), AC-HBO, HLS, and HLS-HBO. Groups receiving HBO (AC-HBO; HLS-HBO) were placed in a cage that was fitted for the animal hyperbaric chamber to maintain HLS. HBO groups received 24 treatments, once a day, 6 d/week using a wound care protocol. The chamber was flushed with 100% oxygen, compressed over 10 min to 2.5 atmospheres absolute (ATA) (22.5 psig), a 90-minute treatment, then a 10 min decompression. After 28 d of HLS, animals were sacrificed under isoflurane anesthesia and thoracic aorta segments isolated. Relaxation of aortic rings was measured in response to acetylcholine (ACh) and sodium nitroprusside (SNP) after pre-constriction with PHE (3×10-7). Constriction of aortic rings was also determined in response to increasing concentrations of PHE. All drugs were administered cumulatively in vessel baths at 10-10-10-4 M. Data were analyzed using four-parameter (i.e., minimum, maximum, EC50, slope) nonlinear regression, and groups compared using 2×2 ANOVA with HBO and HLS as main effects.
Results
Responses to ACh and SNP were not affected by HLS or HBO. However, in response to PHE, there was a decrease in maximum vasoconstriction in HLS compared to controls (44.7±7.3% vs 82.4±6.0%, respectively, p≤0.05) and in HBO compared to controls (48.5±6.5% vs 78.6±6.8%, p≤0.05).
Conclusion
These results indicate that PHE-induced constriction of thoracic aorta is decreased after HLS. HBO did not reverse HLS-induced reductions in contractile responses; instead, HBO independently reduced PHE-stimulated constriction of aortic segments. This suggests that HBO may be useful in conditions where constriction is enhanced, such as diabetes.
Keywords
Hyperbaric oxygen; Vascular reactivity; Hindlimb suspension.
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The Effects of Societal and Structural Barriers on Participation among Individuals with Physical Disabilities
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Previous Issue
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The Athletic Intelligence Quotient and Performance in the National Football League
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Introduction
In the realm of competitive athletics, numerous variables have been examined for predictive utility with respect to player selection/development and outcomes on the field. Notwithstanding important advances, the current predictors only account for a modest amount of variance in outcomes of relevance in the National Football League (NFL).
Objective
The primary objective of this study was to investigate the predictive validity of a new measure of athletic intelligence, the Athletic Intelligence Quotient (AIQ), which is based on the empirically supported Cattell-Horn-Carroll (CHC) Theory of Intelligence. The predictive validity of the AIQ was determined in relation to performance metrics from 146 NFL players across several seasons.
Results
Hierarchical regression analyses indicate that specific AIQ factors accounted for a statistically significant increase in the explanation of variance beyond the current level of evaluation for several performance metrics (e.g., career approximate value; sacks, tackles, rushing yards). Further, specific factors of the AIQ are related to position specific statistics, offering the possibility that performance prediction can be focused in for the specific skills required by a given position.
Discussion
Given the recent impact of analytics in professional sports, and the significant findings noted in the current investigation, the authors discuss the potential importance of the AIQ in the selection and coaching processes.
The Effects of Societal and Structural Barriers on Participation among Individuals with Physical Disabilities
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The 2008 Physical Activity Guidelines recommend that the more than 53 million people living with a physical disability in the United States to participate in regular physical activities consisting of both aerobic and anaerobic components, if possible. Also, if individuals with physical disabilities are unable to meet the recommended physical activity guidelines, they are encouraged to do as much as their physical disability permits. Despite the recommended guidelines, several individuals with physical disabilities do not participate in regular physical activities. Prior research suggests that several societal and structural barriers in sport and exercise environments often negatively affect individuals with physical disabilities. Thus, it is essential for family members, healthcare practitioners, rehabilitation/recreational teams, and community leaders to encourage individuals with physical disabilities to conquer barriers that restrict participation.
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