Validation of the Wilks powerlifting formula

PURPOSE: Because maximal strength varies with body mass, the International Powerlifting Federation (IPF) has adopted a method of adjusting powerlifting events (bench press, BP; squat, SQ; deadlift, DL, and total lift (the sum of BP, DL, and SQ), TOT) by body mass. This method, the Wilks formula, multiplies one's lift by an index based on body mass so that lifters of different size can be compared on the same event. The Wilks formula is not, however, based on published data and has yet to be critically evaluated. The purpose of this investigation, then, was to validate the Wilks formula. METHODS: This was performed by 1) examining residuals bias to verify that the adjusted score does, in fact, lead to no systematic bias based on body mass and 2) by applying a more theoretically supportable allometric model to the same data and comparing the fit with the Wilks approach. Subjects were the current men's and women's world record holders as well as the top two performers for each event in the IPF's 1996 and 1997 World Championships (a total of 30 men and 27 women for each lift). RESULTS: Results of data analysis regarding the Wilks formula indicate that: 1) there is no bias for men's or women's BP and TOT; 2) there is a favorable bias toward intermediate weight class lifters in the women's SQ with no bias for men's SQ; and 3) there is a linear unfavorable bias toward heavier men and women in the DL. Furthermore, the allometric approach indicated a bias against light and heavy men and women which may be considered acceptable given that half as many lifters are found in the lightest and heaviest weight classes as in the intermediate weight classes. CONCLUSION: As used currently (BP and TOT only), the Wilks formula appears to be a valid method to adjust powerlifting scores by body mass.     

Trends in maternal obesity incidence rates, demographic predictors, and health inequalities in 36,821 women over a 15-year period

OBJECTIVE: The aim of this study was to identify trends in maternal obesity incidence over time and to identify those women most at risk and potential-associated health inequalities. DESIGN: Longitudinal database study. SETTING: James Cook University Hospital maternity unit, Middlesbrough, UK. SAMPLE: A total of 36 821 women from 1 January 1990 to 31 December 2004. METHODS: Trends in maternal obesity incidence over time were analysed using chi-square test for trend. Demographic predictor variables were analysed using multivariate logistic regression, adjusting for confounding factors after testing for multicollinearity. National census data were used to place the regional data into the context of the general population. MAIN OUTCOME MEASURE: Trends in maternal obesity incidence. Demographic predictor variables included ethnic group, age, parity, marital status, employment and socio-economic disadvantage. RESULTS: The proportion of obese women at the start of pregnancy has increased significantly over time from 9.9 to 16.0% (P<0.01). This is best described by a quadratic model (P<0.01) showing that the rate is accelerating; by 2010, the rate will have increased to 22% of this population if the trend continues. There is also a significant relationship with maternal obesity and mothers' residing in areas of most deprivation (odds ratio [OR]=2.44, 95% CI=1.98, 3.02, P<0.01), with increasing age (OR=1.04, 95% CI=1.04, 1.05, P<0.01), and parity (OR=1.17, 95% CI=1.12, 1.21, P<0.01). CONCLUSIONS: The incidence of maternal obesity at the start of pregnancy is increasing and accelerating. Predictors of maternal obesity are associated with health inequalities, particularly socio-economic disadvantage.     

Associations between Omega-3 Index,Dopaminergic Genetic Variants and Aggressive and Metacognitive Traits: A Study in Adult Male Prisoners

Omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) are critical for cell membrane structure and function. Human beings have a limited ability to synthesise docosahexaenoic acid (DHA), the main n-3 LCPUFA required for neurological development. Inadequate levels of n-3 LCPUFA can affect the dopaminergic system in the brain and, when combined with genetic and other factors, increase the risk of developing aggression, inattention and impulse-control disorders. In this study, male prisoners were administered questionnaires assessing aggressive behaviour and executive functions. Participants also produced blood sampling for the measurement of the Omega-3 Index and the genotyping of dopaminergic genetic variants. Significant associations were found between functional genetic polymorphism in DBH rs1611115 and verbal aggression and between DRD2 rs4274224 and executive functions. However, the Omega-3 Index was not significantly associated with the tested dopaminergic polymorphisms. Although previous interactions between specific genotypes and n-3 LCPUFA were previously reported, they remain limited and poorly understood. We did not find any association between n-3 LCPUFA and dopaminergic polymorphisms in adult male prisoners; however, we confirmed the importance of genetic predisposition for dopaminergic genes (DBH and DRD2) in aggressive behaviour, memory dysfunction and attention-deficit disorder.     

Nucleotide diversity in the Hsp90 gene in natural populations of Drosophila melanogaster from Australia

Hsp90 is regarded as one of the best candidates for an evolved mechanism that regulates the expression of genetic and phenotypic variability. We examined nucleotide diversity in both the promoter and coding regions of Hsp90, the gene which encodes Hsp90 in Drosophila, in natural populations of Drosophila melanogaster from eastern Australia. We found that Hsp90 is polymorphic for only two nonsynonymous changes in the coding region, both of which are deletions of a lysine residue. One of these lysine deletions was in complete linkage disequilibrium with the inversion In(3L)P, and showed a significant association with latitude. The other lysine deletion reported here for the first time varied from 0 to 15% in natural populations, but did not show a clinal pattern. The regulatory and coding regions of Hsp90 showed very low nucleotide diversity compared to other nuclear genes, and chromosomes containing In(3L)P had lower levels of nucleotide diversity than the standard arrangements. Non‐neutral evolution of Hsp90 was not supported by analyses of either the regulatory or coding regions of the gene. These results are discussed within the context of Hsp90 variation being involved in thermotolerance as well as the expression of genetic and phenotypic variability.     

Dietary intake, serum lipids, insulin resistance and body composition in the era of highly active antiretroviral therapy 'Diet FRS Study'

OBJECTIVES: To investigate (i) differences in dietary fat and energy intake between those reporting and those not reporting fat redistribution syndrome (FRS), and (ii) the relationship between dietary fat, total energy intake, serum biochemistry and the clinical characteristics of the syndrome. DESIGN: A cross-sectional study. SETTING: Outpatient service of a tertiary referral hospital, Sydney, Australia. PATIENTS AND METHODS: Dietary intake, serum lipids and insulin resistance and body composition (fat-free mass, fat mass, waist-to-hip ratio; WHR) were determined in 100 HIV-positive patients whose FRS status was classified on the basis of self-report of body composition changes, verified by clinical examination. RESULTS: There was no significant difference in total or saturated dietary fat intake when grouped by FRS status. There was no significant correlation between dietary saturated or total fat intake and the serum or body composition parameters measured. Total energy intake was higher in those patients reporting FRS (14575 versus 12283 kJ, P = 0.037) after adjustment for age, smoking and exercise status. CONCLUSION: There appears to be no relationship between either dietary saturated or total fat intake and the serum or body composition parameters characteristic of FRS; however, the total energy intake was significantly higher in those with FRS. The nature of the relationship between total energy intake and FRS (cause or effect) warrants further investigation.     

Validity of the allometric cascade model at submaximal and maximal metabolic rates in exercising men

The dependence of metabolic rate (MR) on body mass (M) is described by the general allometric equation MR=aM(b), where, a is a proportionality coefficient and b is the mass exponent. Darveau et al. [Nature 417 (2002), 166] proposed a novel 'multiple-causes' allometric cascade model as a unifying principle of the scaling of MR, at rest and during maximal exercise. We tested the validity of body mass exponents predicted from the model for submaximal and maximal aerobic exercise conditions in 1629 men. MRs were estimated from whole-body oxygen consumption during an incremental treadmill test to voluntary exhaustion. For both submaximal (b=0.83) and maximal (b=0.94) exercise requiring average oxygen consumption rates of around 5-11 times resting values, respectively, the obtained mass exponents were remarkably consistent with predicted values. Moreover, for maximal MR the global mass exponent was significantly greater than for submaximal aerobic metabolism, congruent with the allometric cascade model.     

Caring for the underserved: blending service learning and a web-based curriculum

BACKGROUND: Recognition of health disparities among underserved individuals, whose demographic, geographic, or economic characteristics impede access to health-related services, has led to calls for the development of medical school curricula that address care for the underserved, but reports of the development and evaluation of such curricula are limited. METHODS: Two formats of a curriculum addressing care for the underserved were developed and implemented during the 6-week pediatric clerkship for third-year medical students during the 2003-2004 academic year. One format was faculty-led; the other was web-based. Skills for providing care to underserved families were taught through didactic, experiential, and service-learning curriculum components. Novel core curriculum elements included a screening tool for recognizing underserved patients and an independent clinical project through which students linked underserved families with community health resources. Analyses from 2004-2005 compared pre- and post-curriculum knowledge and attitudes of web-based students (n = 29) to those receiving either the faculty-led (n = 36) or the established "readings-only" curriculum (n = 35). Qualitative data from service learning projects were analyzed to assess clinical skills. RESULTS: Compared to students in the established curriculum, both web-based and faculty-led students demonstrated improved knowledge (p < 0.001) and attitudes (p < 0.05) about caring for the underserved. Both web-based and faculty-led students were successful in recognizing and addressing underserved health issues in the clinical setting. CONCLUSIONS: Faculty-led and web-based curricula can equally improve student knowledge, attitudes, and skills about caring for the underserved.