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1. Correction to: Bone mineral density in high-level endurance runners: part A—site-specific characteristics

Author

Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Sale, C, Hennis, PJ, Day, SH, Stebbings, GK, Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Sale, C, Hennis, PJ, Day, SH, and Stebbings, GK

Abstract

The original version of this article unfortunately contained a mistake. Figure 1C was missing The corrected Fig. 1 should have appeared as shown in the following page. The original article has been corrected.

Published
2022

2. Bone mineral density in high-level endurance runners: Part B—genotype-dependent characteristics

Author

Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Sale, C, Hennis, PJ, Day, SH, Stebbings, GK, Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Sale, C, Hennis, PJ, Day, SH, and Stebbings, GK

Abstract

Purpose Inter-individual variability in bone mineral density (BMD) exists within and between endurance runners and non-athletes, probably in part due to differing genetic profiles. Certainty is lacking, however, regarding which genetic variants may contribute to BMD in endurance runners and if specific genotypes are sensitive to environmental factors, such as mechanical loading via training. Method Ten single-nucleotide polymorphisms (SNPs) were identified from previous genome-wide and/or candidate gene association studies that have a functional effect on bone physiology. The aims of this study were to investigate (1) associations between genotype at those 10 SNPs and bone phenotypes in high-level endurance runners, and (2) interactions between genotype and athlete status on bone phenotypes. Results Female runners with P2RX7 rs3751143 AA genotype had 4% higher total-body BMD and 5% higher leg BMD than AC+CC genotypes. Male runners with WNT16 rs3801387 AA genotype had 14% lower lumbar spine BMD than AA genotype non-athletes, whilst AG+GG genotype runners also had 5% higher leg BMD than AG+GG genotype non-athletes. Conclusion We report novel associations between P2RX7 rs3751143 genotype and BMD in female runners, whilst differences in BMD between male runners and non-athletes with the same WNT16 rs3801387 genotype existed, highlighting a potential genetic interaction with factors common in endurance runners, such as high levels of mechanical loading. These findings contribute to our knowledge of the genetic associations with BMD and improve our understanding of why some runners have lower BMD than others.

Published
2022

4. Bone mineral density in high-level endurance runners: part A—site-specific characteristics

Author

Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Sale, C, Hennis, PJ, Day, SH, Stebbings, GK, Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Sale, C, Hennis, PJ, Day, SH, and Stebbings, GK

Abstract

Purpose Physical activity, particularly mechanical loading that results in high-peak force and is multi-directional in nature, increases bone mineral density (BMD). In athletes such as endurance runners, this association is more complex due to other factors such as low energy availability and menstrual dysfunction. Moreover, many studies of athletes have used small sample sizes and/or athletes of varying abilities, making it difficult to compare BMD phenotypes between studies. Method The primary aim of this study was to compare dual-energy X-ray absorptiometry (DXA) derived bone phenotypes of high-level endurance runners (58 women and 45 men) to non-athletes (60 women and 52 men). Our secondary aim was to examine the influence of menstrual irregularities and sporting activity completed during childhood on these bone phenotypes. Results Female runners had higher leg (4%) but not total body or lumbar spine BMD than female non-athletes. Male runners had lower lumbar spine (9%) but similar total and leg BMD compared to male non-athletes, suggesting that high levels of site-specific mechanical loading was advantageous for BMD in females only and a potential presence of reduced energy availability in males. Menstrual status in females and the number of sports completed in childhood in males and females had no influence on bone phenotypes within the runners. Conclusion Given the large variability in BMD in runners and non-athletes, other factors such as variation in genetic makeup alongside mechanical loading probably influence BMD across the adult lifespan.

Published
2021

5. The interactions of physical activity, exercise and genetics and their associations with bone mineral density: implications for injury risk in elite athletes

Author

Herbert, AJ, Williams, AG, Hennis, PJ, Erskine, RM, Sale, C, Day, SH, Stebbings, GK, Herbert, AJ, Williams, AG, Hennis, PJ, Erskine, RM, Sale, C, Day, SH, and Stebbings, GK

Abstract

Low bone mineral density (BMD) is established as a primary predictor of osteoporotic risk and can also have substantial implications for athlete health and injury risk in the elite sporting environment. BMD is a highly multi-factorial phenotype influenced by diet, hormonal characteristics and physical activity. The interrelationships between such factors, and a strong genetic component, suggested to be around 50–85% at various anatomical sites, determine skeletal health throughout life. Genome-wide association studies and case–control designs have revealed many loci associated with variation in BMD. However, a number of the candidate genes identified at these loci have no known associated biological function or have yet to be replicated in subsequent investigations. Furthermore, few investigations have considered gene–environment interactions—in particular, whether specific genes may be sensitive to mechanical loading from physical activity and the outcome of such an interaction for BMD and potential injury risk. Therefore, this review considers the importance of physical activity on BMD, genetic associations with BMD and how subsequent investigation requires consideration of the interaction between these determinants. Future research using well-defined independent cohorts such as elite athletes, who experience much greater mechanical stress than most, to study such phenotypes, can provide a greater understanding of these factors as well as the biological underpinnings of such a physiologically “extreme” population. Subsequently, modification of training, exercise or rehabilitation programmes based on genetic characteristics could have substantial implications in both the sporting and public health domains once the fundamental research has been conducted successfully.

Published
2018

6. No association between ACTN3 R577X and ACE I/D polymorphisms and endurance running times in 698 Caucasian athletes

Author

Papadimitriou, ID, Lockey, SJ, Voisin, S, Herbert, AJ, Garton, F, Houweling, PJ, Cieszczyk, P, Maciejewska-Skrendo, A, Sawczuk, M, Massidda, M, Calò, CM, Druzhevskaya, AM, Astratenkova, IV, Kouvatsi, A, Ahmetov, II, Jacques, M, Stebbings, G, Heffernan, SM, Day, SH, Erskine, RM, Pedlar, C, Kipps, C, North, KN, Williams, AG, Eynon, N, Papadimitriou, ID, Lockey, SJ, Voisin, S, Herbert, AJ, Garton, F, Houweling, PJ, Cieszczyk, P, Maciejewska-Skrendo, A, Sawczuk, M, Massidda, M, Calò, CM, Druzhevskaya, AM, Astratenkova, IV, Kouvatsi, A, Ahmetov, II, Jacques, M, Stebbings, G, Heffernan, SM, Day, SH, Erskine, RM, Pedlar, C, Kipps, C, North, KN, Williams, AG, and Eynon, N

Abstract

Background: Studies investigating associations between ACTN3 R577X and ACE I/D genotypes and endurance athletic status have been limited by small sample sizes from mixed sport disciplines and lack quantitative measures of performance. Aim: To examine the association between ACTN3 R577X and ACE I/D genotypes and best personal running times in a large homogeneous cohort of endurance runners. Methods: We collected a total of 1064 personal best 1500 m, 3000 m, 5000 m and marathon running times of 698 male and female Caucasian endurance athletes from six countries (Australia, Greece, Italy, Poland, Russia and UK). Athletes were genotyped for ACTN3 R577X and ACE ID variants. Results: There was no association between ACTN3 R577X or ACE I/D genotype and running performance at any distance in men or women. Mean (SD) marathon times (in s) were for men: ACTN3 RR 9149 (593), RX 9221 (582), XX 9129 (582) p=0.94; ACE DD 9182 (665), ID 9214 (549), II 9155 (492) p=0.85; for women: ACTN3 RR 10796 (818), RX 10667 (695), XX 10675 (553) p=0.36; ACE DD 10604 (561), ID 10766 (740), II 10771 (708) p=0.21. Furthermore, there were no associations between these variants and running time for any distance in a sub-analysis of athletes with personal records within 20% of world records. Conclusions: Thus, consistent with most case-control studies, this multi-cohort quantitative analysis demonstrates it is unlikely that ACTN3 XX genotype provides an advantage in competitive endurance running performance. For ACE II genotype, some prior studies show an association but others do not. Our data indicate it is also unlikely that ACE II genotype provides an advantage in endurance running.

Published
2018

7. No association between tendon-related genes and performance in elite European Caucasian marathon runners

Author

Stebbings, G, Herbert, AJ, Brazier, J, Lockey, SJ, Erskine, RM, Day, SH, and Williams, AG

Abstract

Tendons adapt to load under normal physiological conditions, however, under extreme loading conditions, such as those experienced by elite endurance athletes, incomplete adaptation may occur and cause injury. The prevalence of tendinopathies in elite endurance athletes is approximately 50%, thus variability exists in an athlete's tolerance to extreme loading. A number of intrinsic and extrinsic factors contribute to modulating injury risk, some of which are modifiable and others, such as genetic variants, are non-modifiable. It was hypothesized that elite marathon runners would possess a genotype associated with enhanced tendon function, and thus protective against tendinopathy. Here, we compared the genotype frequencies of six genetic variants (COL1A1 rs1800012, VEGFA rs699947, TIMP2 rs4789932, MMP3 rs591058, MMP3 rs650108, MMP3 rs679620), previously associated with tendinopathy, in elite (men

Published
2017

8. Fat mass and obesity associated (FTO) gene influences skeletal muscle phenotypes in non-resistance trained males and elite rugby playing position

Author

Heffernan, SM, Stebbings, GK, Kilduff, LP, Erskine, RM, Day, SH, Morse, CI, McPhee, JS, Cook, CJ, Vance, B, Ribbans, WJ, Raleigh, SM, Roberts, C, Bennett, MA, Wang, G, Collins, M, Pitsiladis, YP, Williams, AG, Department of Human Biology, and Faculty of Health Sciences

Subjects
Adult, Male, obesity, Adolescent, Genotype, Genetics and Population Dynamics, males, Football, Alpha-Ketoglutarate-Dependent Dioxygenase FTO, quantitative polymerase chain reaction, Plant Genetics, cachexia, Polymorphism, Single Nucleotide, RC1200, sarcopenia, Young Adult, Genetics, Humans, Genetics(clinical), Genetic Predisposition to Disease, skeletal muscle, Muscle, Skeletal, RugbyGene project, Animal Genetics and Genomics, Lean mass, Life Sciences, Resistance Training, Genomics, DNA, Phenotype, genotyping, general, Athletes, alleles, IRX3, muscles, dual-energy X-ray absorptiometry, Microbial Genetics and Genomics, Research Article
Abstract

Background FTO gene variants have been associated with obesity phenotypes in sedentary and obese populations, but rarely with skeletal muscle and elite athlete phenotypes. Methods In 1089 participants, comprising 530 elite rugby athletes and 559 non-athletes, DNA was collected and genotyped for the FTO rs9939609 variant using real-time PCR. In a subgroup of non-resistance trained individuals (NT; n = 120), we also assessed structural and functional skeletal muscle phenotypes using dual energy x-ray absorptiometry, ultrasound and isokinetic dynamometry. In a subgroup of rugby athletes (n = 77), we assessed muscle power during a countermovement jump. Results In NT, TT genotype and T allele carriers had greater total body (4.8% and 4.1%) and total appendicular lean mass (LM; 3.0% and 2.1%) compared to AA genotype, with greater arm LM (0.8%) in T allele carriers and leg LM (2.1%) for TT, compared to AA genotype. Furthermore, the T allele was more common (94%) in selected elite rugby union athletes (back three and centre players) who are most reliant on LM rather than total body mass for success, compared to other rugby athletes (82%; P = 0.01, OR = 3.34) and controls (84%; P = 0.03, OR = 2.88). Accordingly, these athletes had greater peak power relative to body mass than other rugby athletes (14%; P = 2 x 10 -6 ). Conclusion Collectively, these results suggest that the T allele is associated with increased LM and elite athletic success. This has implications for athletic populations, as well as conditions characterised by low LM such as sarcopenia and cachexia.

Published
2017
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9. Associations of bone mineral density-related genes and marathon performance in elite European Caucasian marathon runners.

Author

Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Hennis, PJ, Sale, C, Day, SH, Stebbings, GK, Herbert, AJ, Williams, AG, Lockey, SJ, Erskine, RM, Hennis, PJ, Sale, C, Day, SH, and Stebbings, GK

Abstract

Bone mineral density (BMD) is a multi-factorial phenotype determined by factors such as physical activity, diet and a sizeable genetic component. Athletic populations tend to possess higher BMD than non-athletes due to a larger volume of exercise completed. Despite this, some endurance runners can possess low BMD and/or suffer stress fractures, which can have negative impacts on their health and performance. Therefore, we hypothesised that elite endurance runners would possess a genotype associated with enhanced BMD and a reduced risk of injury, resulting in less training interruption and greater potential success. The study compared the genotype and allele frequencies of 5 genetic variants associated with BMD (LRP5 rs3736228, TNFRSF11B rs4355801, VDR rs2228570, WNT16 rs3801387, AXIN1 rs9921222) in elite (men < 2 h 30 min, n = 110; women < 3 h 00 min, n = 98) and sub-elite (men 2 h 30 min – 2 h 45 min, n = 181; women 3 h 00 min – 3 h 15 min, n = 67) marathon runners with those of a non-athlete control population (n = 474). We also investigated whether marathon personal best time was associated with a more “advantageous” BMD genotype. Congruent with our hypothesis, the “risk” T allele for the AXIN1 rs9921222 polymorphism was 5% more frequent in the control group than in sub-elites (P = 0.030, χ2 = 4.69) but no further differences were observed for this variant (P ≥ 0.083, χ2 ≤ 4.98). WNT16 rs3801387 genotype frequency differed between athletes and controls (P = 0.002, χ2 = 12.02) and elites vs controls (P = 0.008, χ2 = 9.72), as did allele frequency. However, contrary to our hypothesis, it was the “risk” A allele that was ~5% more frequent in athletes than controls. Similarly, when combining data from all 5 variants, the athletes had a lower Total Genotype Score than controls (53.6 vs 65.7; P ≤ 0.001), again suggesting greater genetic susceptibility to bone injury in athletes. Personal best times were not associated with genotype in any comparison. These results sugg

Published
2017

10. COL5A1 gene variants previously associated with reduced soft tissue injury risk are associated with elite athlete status in rugby

Author

Heffernan, SM, Kilduff, LP, Erskine, RM, Day, SH, Stebbings, GK, Cook, CJ, Raleigh, SM, Bennett, MA, Wang, G, Collins, M, Pitsiladis, YP, Williams, AG, Heffernan, SM, Kilduff, LP, Erskine, RM, Day, SH, Stebbings, GK, Cook, CJ, Raleigh, SM, Bennett, MA, Wang, G, Collins, M, Pitsiladis, YP, and Williams, AG

Abstract

Background: Two common single nucleotide polymorphisms within the COL5A1 gene (SNPs; rs12722 C/T and rs3196378 C/A) have previously been associated with tendon and ligament pathologies. Given the high incidence of tendon and ligament injuries in elite rugby athletes, we hypothesised that both SNPs would be associated with career success. Methods: In 1105 participants (RugbyGene project), comprising 460 elite rugby union (RU), 88 elite rugby league athletes and 565 non-athlete controls, DNA was collected and genotyped for the COL5A1 rs12722 and rs3196378 variants using real-time PCR. Results: For rs12722, the injury-protective CC genotype and C allele were more common in all athletes (21% and 47%, respectively) and RU athletes (22% and 48%) than in controls (16% and 41%, P ≤ 0.01). For rs3196378, the CC genotype and C allele were overrepresented in all athletes (23% and 48%) and RU athletes (24% and 49%) compared with controls (16% and 41%, P ≤ 0.02). The CC genotype in particular was overrepresented in the back and centres (24%) compared with controls, with more than twice the odds (OR = 2.25, P = 0.006) of possessing the injury-protective CC genotype. Furthermore, when considering both SNPs simultaneously, the CC–CC SNP-SNP combination and C–C inferred allele combination were higher in all the athlete groups (≥ 18% and ≥ 43%) compared with controls (13% and 40%; P = 0.01). However, no genotype differences were identified for either SNP when RU playing positions were compared directly with each other. Conclusion: It appears that the C alleles, CC genotypes and resulting combinations of both rs12722 and rs3196378 are beneficial for rugby athletes to achieve elite status and carriage of these variants may impart an inherited resistance against soft tissue injury, despite exposure to the high-risk environment of elite rugby. These data have implications for the management of inter-individual differences in injury risk amongst elite athletes.

Published
2017

11. Polymorphisms in PTK2 are associated with skeletal muscle specific force: an independent replication study

Author

Stebbings, GK, Day, SH, Williams, A, Morse, C, Stebbings, GK, Day, SH, Williams, A, and Morse, C

Abstract

Purpose The aim of the study was to investigate two single nucleotide polymorphisms (SNP) in PTK2 for associations with human muscle strength phenotypes in healthy men. Methods Measurement of maximal isometric voluntary knee extension (MVCKE) torque, net MVCKE torque and vastus lateralis (VL) specific force, using established techniques, was completed on 120 Caucasian men (age = 20.6 ± 2.3 year; height = 1.79 ± 0.06 m; mass = 75.0 ± 10.0 kg; mean ± SD). All participants provided either a blood (n = 96) or buccal cell sample, from which DNA was isolated and genotyped for the PTK2 rs7843014 A/C and rs7460 A/T SNPs using real-time polymerase chain reaction. Results Genotype frequencies for both SNPs were in Hardy–Weinberg equilibrium (X2 ≤ 1.661, P ≥ 0.436). VL specific force was 8.3% higher in rs7843014 AA homozygotes than C-allele carriers (P = 0.017) and 5.4% higher in rs7460 AA homozygotes than T-allele carriers (P = 0.029). No associations between either SNP and net MVCKE torque (P ≥ 0.094) or peak MVCKE torque (P ≥ 0.107) were observed. Conclusions These findings identify a genetic contribution to the inter-individual variability within muscle specific force and provides the first independent replication, in a larger Caucasian cohort, of an association between these PTK2 SNPs and muscle specific force, thus extending our understanding of the influence of genetic variation on the intrinsic strength of muscle.

Published
2017

16. Association of ACTN3 R577X but not ACE I/D gene variants with elite rugby union player status and playing position.

Author

Heffernan, SM, Kilduff, LP, Erskine, RM, Day, SH, McPhee, JS, McMahon, GE, Stebbings, GK, Neale, JP, Lockey, SJ, Ribbans, WJ, Cook, CJ, Vance, B, Raleigh, SM, Roberts, C, Bennett, MA, Wang, G, Collins, M, Pitsiladis, YP, Williams, Alun G., Heffernan, SM, Kilduff, LP, Erskine, RM, Day, SH, McPhee, JS, McMahon, GE, Stebbings, GK, Neale, JP, Lockey, SJ, Ribbans, WJ, Cook, CJ, Vance, B, Raleigh, SM, Roberts, C, Bennett, MA, Wang, G, Collins, M, Pitsiladis, YP, and Williams, Alun G.

Abstract

We aimed to quantify the ACE I/D and ACTN3 R577X (rs1815739) genetic variants in elite rugby athletes (rugby union and league) and compare genotype frequencies to controls and between playing positions. The rugby athlete cohort consisted of 507 Caucasian men, including 431 rugby union athletes that for some analyses were divided into backs and forwards and into specific positional groups: front five, back row, half backs, centers, and back three. Controls were 710 Caucasian men and women. Real-time PCR of genomic DNA was used to determine genotypes using TaqMan probes and groups were compared using χ(2) and odds ratio (OR) statistics. Correction of P values for multiple comparisons was according to Benjamini-Hochberg. There was no difference in ACE I/D genotype between groups. ACTN3 XX genotype tended to be underrepresented in rugby union backs (15.7%) compared with forwards (24.8%, P = 0.06). Interestingly, the 69 back three players (wings and full backs) in rugby union included only six XX genotype individuals (8.7%), with the R allele more common in the back three (68.8%) than controls (58.0%; χ(2) = 6.672, P = 0.04; OR = 1.60) and forwards (47.5%; χ(2) = 11.768, P = 0.01; OR = 2.00). Association of ACTN3 R577X with playing position in elite rugby union athletes suggests inherited fatigue resistance is more prevalent in forwards, while inherited sprint ability is more prevalent in backs, especially wings and full backs. These results also demonstrate the advantage of focusing genetic studies on a large cohort within a single sport, especially when intrasport positional differences exist, instead of combining several sports with varied demands and athlete characteristics.

Published
2016

17. Genetic testing in exercise and sport - have direct-to-consumer genetic tests come of age?

Author

Williams, Alun G., Heffernan, SM, and Day, SH

Abstract

The general consensus amongst sport and exercise genetics researchers is that genetic tests based on current knowledge have little or no role to play in talent identifi cation or the individualised prescription of training to maximise performance or minimise injury risk. Despite this, genetic tests related to sport and exercise are widely available on a commercial basis. This study assessed commercially-available genetic tests related to sport and exercise currently marketed via the internet. Twenty-two companies were identified as providing direct-to-consumer (DTC) genetic tests marketed in relation to human sport or exercise performance or injury. The most commonly-tested variant was the R577X SNP in the ACTN3 gene, tested by 85% of the 13 companies that appear to present information about their genetic tests on websites - which corresponds with our assessment that ACTN3 R577X is currently the polymorphism with the strongest scientific evidence in support of an association with sport and exercise phenotypes. 54% of companies that present information about their genetic tests used panels of 2-21 variants, including several with very limited supporting scientific evidence. 46% of companies tested just a single variant, with very low ability to explain complex sport and exercise phenotypes. It is particularly disappointing that 41% of companies off ering DTC genetic tests related to exercise and sport did not appear to state publicly the genetic variants they assess, making scrutiny by academic scholars and consumers impossible. Companies off ering DTC genetic tests related to sport and exercise should ensure that they are responsible in their activities.

Published
2014

18. Genomics in rugby union: A review and future prospects

Author

Heffernan, SM, Kilduff, LP, Day, SH, Pitsiladis, YP, Williams, Alun G., Heffernan, SM, Kilduff, LP, Day, SH, Pitsiladis, YP, and Williams, Alun G.

Abstract

This article introduces some aspects of sports genomics in a rugby union context, considers the rugby-specific genetic data in the published literature and outlines the next research steps required if the potential applications of genetic technology in rugby union, also identified here, are to become possible. A substantial proportion of the inter-individual variation for many traits related to rugby performance, including strength, short-term muscle power, VO2 max, injury susceptibility and the likelihood of being an elite athlete is inherited and can be investigated using molecular genetic techniques. In sports genomics, significant efforts have been made in recent years to develop large DNA biobanks of elite athletes for detailed exploration of the heritable bases of those traits. However, little effort has been devoted to the study of rugby athletes, and most of the little research that has focused on rugby was conducted with small cohorts of non-elite players. With steadily growing knowledge of the molecular mechanisms underpinning complex performance traits and the aetiology of injury, investigating sports genomics in the context of rugby is now a viable proposition and a worthwhile endeavour. The RugbyGene project we describe briefly in this article is a multi-institutional research collaboration in rugby union that will perform molecular genetic analyses of varying complexity. Genetic tests could become useful tools for rugby practitioners in the future and provide complementary and additional information to that provided by the non-genetic tests currently used.

Published
2015

19. Genetic Testing for Sports Performance, Responses to Training and Injury Risk: Practical and Ethical Considerations

Author

Sportbiologie, Williams AG, Wackerhage H, Day SH, Sportbiologie, and Williams AG, Wackerhage H, Day SH

Abstract

This paper addresses practical and ethical considerations regarding genetic tests to predict performance and/or risk of exercise-related injury or illness. Various people might wish to conduct sport-related genetic tests for a variety of reasons. For example, an individual might seek personal genetic information to help guide their own sport participation. A sports coach might wish to test young athletes to aid team selection or individualize training. A physician might want to predict the risk of injury or illness in athletes and advise regarding selection or preventative measures. An insurance company might seek to estimate the risk of career-threatening injury for athletes based partly on genetic information. Whilst this information is, in part, encoded in our DNA sequence, the available tests allow generally only a poor prediction of the aforementioned variables. In other words, the current genetic tests and analysis methods are not powerful enough to inform important decisions in sport to a substantial degree. It is particularly disappointing that more than half of the commercially available genetic tests related to exercise and sport do not appear to identify publicly the genetic variants they assess, making scrutiny by academic scholars and consumers (or their representatives) impossible. There are also challenging ethical issues to consider. For example, the imposition of genetic tests on individuals (especially young people) by third parties is potentially susceptible to abuse. Scientists and practitioners should understand the limitations of the tests currently available, the ethical concerns and the importance of counselling before and after testing so that they are only used in a responsible manner.

Published
2015

20. Genomics as a practical tool in sport - have we reached the starting line?

Author

Williams, Alun G., Day, SH, Lockey, SJ, Heffernan, SM, Erskine, RM, Williams, Alun G., Day, SH, Lockey, SJ, Heffernan, SM, and Erskine, RM

Abstract

The genetic component of athletic performance approximates 50%, depending on which specific element of performance is considered. Limited genetic testing is already available commercially and genetic tests are likely to become powerful tools to improve sport performance in the future. Currently, however, selection of athletes for training squads or competition based on genomic data is premature. Larger volumes of longitudinal data within individual sports are needed to determine the efficacy of using genomic data in the management of elite athletes via manipulation of training load and diet based on personal genomic information.

Published
2014

24. Circulating angiotension converting enzyme activity is correlated with muscle strength.

Author

Williams AG, Day SH, Folland JP, Gohlke P, Dhamrait S, and Montgomery HE

Abstract

PURPOSE: The D-variant of the angiotensin-1 converting enzyme (ACE) gene is associated with higher circulating and tissue ACE activity. Some studies have suggested a similar association of genotype with muscle strength or the gain in strength in response to training. This study has assessed the relationship between circulating ACE activity, strength, and the response to training. METHODS: Eighty-one untrained men were tested for quadriceps muscle strength, and 44 of these performed an 8-wk program of dynamic strength training of the quadriceps muscle group. Venous blood was obtained for assessment of circulating ACE activity before and after the training program. ACE genotype was also determined. RESULTS: At baseline, circulating ACE activity was significantly correlated with isometric (r = 0.25-0.29, P < 0.02) and isokinetic (r = 0.38, P < 0.0005) quadriceps muscle strength. ACE genotype also seemed to be related to pretraining muscle strength. However, circulating ACE activity showed no significant association with the 9-14% mean increases of muscle strength in response to the training intervention. ACE genotype also showed no association with the training-induced change in muscle strength. Circulating ACE activity did not change significantly after the training program. CONCLUSIONS: The data support a role for ACE in the regulation of human skeletal muscle strength, but do not confirm a role in altering the response to short-term training. [ABSTRACT FROM AUTHOR]

Published
2005

25. Osteoporosis prevention: knowledge and behavior in a southwestern community.

Author

Larkey LK, Day SH, Houtkooper L, and Renger R

Abstract

Prior to developing an osteoporosis prevention education program and social marketing campaign, we sought to (a) establish current status of osteoporosis-related knowledge and behavior among women aged 25-55 years in Maricopa County, Arizona, and (b) assess factors that segment the population by age and ethnicity. Two-hundred women were surveyed by telephone using random-digit dialing selection. Data demonstrated knowledge of need to consume adequate calcium, but mixed understanding of forms of exercise that help prevent osteoporosis. Knowledge of osteoporosis prevention did not differ as a function of menopause status. Differences for Hispanic versus non-Hispanic women's knowledge showed fewer correct responses for Hispanics for dietary and physical activity questions, and more correct responses on the relationship between body weight and osteoporosis risk. Hispanic women and post-menopausal women generally fit the pattern of higher risk behaviors with Hispanic women exercising and using HRT less and postmenopausal women reporting lower calcium intake and physical activity and more tobacco use. Hispanic women appeared to have similar intake of dietary calcium despite lower levels of milk products. Social marketing campaigns for osteoporosis prevention should be segmented for cultural and age differences, especially considering differences in orientations toward exercise, milk consumption, and competing emphasis on other diseases. [ABSTRACT FROM AUTHOR]

Published
2003
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29. Genomics as a practical tool in sport - have we reached the starting line?

Author

Williams, Alun G., Day, SH, Lockey, SJ, Heffernan, SM, and Erskine, RM

Subjects
RC1200
Abstract

The genetic component of athletic performance approximates 50%, depending on which specific element of performance is considered. Limited genetic testing is already available commercially and genetic tests are likely to become powerful tools to improve sport performance in the future. Currently, however, selection of athletes for training squads or competition based on genomic data is premature. Larger volumes of longitudinal data within individual sports are needed to determine the efficacy of using genomic data in the management of elite athletes via manipulation of training load and diet based on personal genomic information.

30. 18 No association between tendon-related genes and performance in elite european caucasian marathon runners

Author

Stebbings, GK, Herbert, AJ, Brazier, J, Lockey, SJ, Erskine, RM, Day, SH, and Williams, AG

Abstract

Tendons adapt to load under normal physiological conditions, however, under extreme loading conditions, such as those experienced by elite endurance athletes, incomplete adaptation may occur and cause injury. The prevalence of tendinopathies in elite endurance athletes is approximately 50%, thus variability exists in an athlete’s tolerance to extreme loading. A number of intrinsic and extrinsic factors contribute to modulating injury risk, some of which are modifiable and others, such as genetic variants, are non-modifiable. It was hypothesised that elite marathon runners would possess a genotype associated with enhanced tendon function, and thus protective against tendinopathy. Here, we compared the genotype frequencies of six genetic variants (COL1A1 rs1800012, VEGFA rs699947, TIMP2 rs4789932, MMP3 rs591058, MMP3 rs650108, MMP3 rs679620), previously associated with tendinopathy, in elite (men <2 hour 30 min, n=109, women <3 hour 00 min, n=99) and sub-elite (men 2 hour 30 min-2 h 45 min, n=189; women 3 hour 00 min-3 h 15 min, n=71) marathon runners with those of a non-athletic control group (n=564). Genotype associations with marathon personal best time in the athlete group were also investigated. All participants provided either a whole blood, saliva or buccal cell sample, from which DNA was isolated, and genotyped for all six variants using real-time PCR. Genotype frequency differed between athletes and controls for TIMP2 rs4789932 (TT=17%, CT=51%, CC=32% vs TT=22%, CT=42%, CC=36%, respectively; χ2=8.135, p=0.017) only. However, there was no clear difference in allele frequencies between groups for TIMP2 rs4789932. MMP3 rs650108 genotype frequency differed between female elite and sub-elite athletes (χ2=11.913, p=0.003) only and, as hypothesised, it was the ‘risk’ A-allele that was ~10% less frequent in the elite, than sub-elite athletes. Following combination of all genotype data into a total genotype score, no differences in score between athletes and controls were observed (t=2.93, p=0.769). Similarly, no associations between total genotype score and marathon personal best time in male and female runners were observed (r≤0.066, p≥0.394). The results suggest elite marathon runners do not possess a genotype protective against tendinopathy, at least for the tendon-related genetic variants we investigated.

Published
2017
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34. (Farm) map number three (Santa Clara Co., California). (with) Estado que manifesta las suertes de tiend. reparteds. a los poblado. del Pueblo S'n. Josef ... (Thompson & West, San Francisco, Cala. 1876)

Author

Day, Sherman, 1806-1884 and Thompson & West

Subjects
San Jose (Calif.), Santa Clara County (Calif.), San Francisco, California
Abstract

Hand col. lithographed map. Relief shown by hachures. Shows townships, Public Land Survey System sections, etc., land grants, owners of large parcels with acreage, roads, railroads, schools, etc. Inset shows landowners, etc., and has additional title: Fac-simile of the original plat of the Pueblo de San Jose taken from the surveys made in 1781 and now on file in the archives of the City of Mexico., Full color. Atlas is bound in half leather brown cloth covered boards with "New historical atlas of Santa Clara Co. California. Illustrated. Thompson & West 1876" stamped in gilt on the front cover and blind stamped on the back. David Rumsey Collection copy includes 3 ms. letters regarding the Almaden Mine view dispute., Phillips, 1464; LeGear. Atlases of the United States, L 478.

Published
1876

35. (Farm) map number two (Santa Clara Co., California). (Thompson & West, San Francisco, Cala. 1876)

Author

Day, Sherman, 1806-1884 and Thompson & West

Subjects
Santa Clara County (Calif.), San Francisco, California
Abstract

Hand col. lithographed map. Relief shown by hachures. Shows townships, land grants, owners of large parcels with acreage, roads, railroads, schools, etc., Full color. Atlas is bound in half leather brown cloth covered boards with "New historical atlas of Santa Clara Co. California. Illustrated. Thompson & West 1876" stamped in gilt on the front cover and blind stamped on the back. David Rumsey Collection copy includes 3 ms. letters regarding the Almaden Mine view dispute., Phillips, 1464; LeGear. Atlases of the United States, L 478.

Published
1876

36. (Farm) map number one (Santa Clara Co., California). (with) Plat of Alviso, part of Sherman Day's copy of orig. map. (with) Map of villa lands of Mountain View, recorded March, 1865. (with) Mayfield, original town as surveyed for Wm. Paul, March 20th.,1867. (Thompson & West, San Francisco, Cala. 1876)

Author

Day, Sherman, 1806-1884 and Thompson & West

Subjects
Alviso (San Jose, Calif.), Mountain View (Calif.), Santa Clara County (Calif.), San Francisco, California
Abstract

Hand col. lithographed map. Relief shown by hachures. Covers Fremont Township. Shows townships, land grants, owners of large parcels with acreage, roads, railroads, schools, etc. Inset maps show block and lot numbers; scales vary. Mountain View map also includes title: Map of Bay View laid out by Castro, not recorded., Full color. Atlas is bound in half leather brown cloth covered boards with "New historical atlas of Santa Clara Co. California. Illustrated. Thompson & West 1876" stamped in gilt on the front cover and blind stamped on the back. David Rumsey Collection copy includes 3 ms. letters regarding the Almaden Mine view dispute., Phillips, 1464; LeGear. Atlases of the United States, L 478.

Published
1876

37. Concussion-Associated Gene Variant COMT rs4680 Is Associated With Elite Rugby Athlete Status.

Author

Antrobus MR, Brazier J, Callus P, Herbert AJ, Stebbings GK, Day SH, Kilduff LP, Bennett MA, Erskine RM, Raleigh SM, Collins M, Pitsiladis YP, Heffernan SM, and Williams AG

Subjects
Humans, Male, Female, Adult, Rugby, Polymorphism, Genetic, Athletes, Catechol O-Methyltransferase genetics, Football injuries, Brain Concussion genetics, Brain Concussion psychology
Abstract

Objective: Concussions are common match injuries in elite rugby, and reports exist of reduced cognitive function and long-term health consequences that can interrupt or end a playing career and produce continued ill health. The aim of this study was to investigate the association between elite rugby status and 8 concussion-associated risk polymorphisms. We hypothesized that concussion-associated risk genotypes and alleles would be underrepresented in elite rugby athletes compared with nonathletes., Design: A case-control genetic association study., Setting: Institutional (university)., Participants: Elite White male rugby athletes [n = 668, mean (SD) height 1.85 (0.07) m, mass 102 (12) kg, and age 29 (7) years] and 1015 nonathlete White men and women (48% men)., Interventions: Genotype was the independent variable, obtained by PCR of genomic DNA using TaqMan probes., Main Outcome Measure: Elite athlete status with groups compared using χ 2 and odds ratio (OR)., Results: The COMT rs4680 Met/Met (AA) genotype, Met allele possession, and Met allele frequency were lower in rugby athletes (24.8%, 74.6%, and 49.7%, respectively) than nonathletes (30.2%, 77.6%, and 54.0%; P < 0.05). The Val/Val (GG) genotype was more common in elite rugby athletes than nonathletes (OR 1.39, 95% confidence interval 1.04-1.86). No other polymorphism was associated with elite athlete status., Conclusions: Elite rugby athlete status is associated with COMT rs4680 genotype that, acting pleiotropically, could affect stress resilience and behavioral traits during competition, concussion risk, and/or recovery from concussion. Consequently, assessing COMT rs4680 genotype might aid future individualized management of concussion risk among athletes., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Published
2023
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38. Gene variants previously associated with reduced soft-tissue injury risk: Part 2 - Polygenic associations with elite status in Rugby.

Author

Brazier J, Antrobus MR, Herbert AJ, Callus PC, Khanal P, Stebbings GK, Day SH, Heffernan SM, Kilduff LP, Bennett MA, Erskine RM, Raleigh SM, Collins M, Pitsiladis YP, and Williams AG

Subjects
Humans, Genotype, Athletes, Rugby, MicroRNAs
Abstract

Part 1 of this genetic association series highlighted several genetic variants independently associated with elite status in rugby. However, it is highly likely that the genetic influence on elite status is polygenic due to the interaction of multiple genes. Therefore, the aim of the present study was to investigate whether polygenic profiles of elite rugby athletes differed from non-athletes utilising 13 genetic polymorphisms previously associated with tendon/ligament injury. Total genotype score (TGS) was calculated and multifactor dimensionality reduction (MDR) was used to calculate SNP-SNP epistasis interactions. Based on our elite rugby data from Part 1, mean TGS was significantly higher in elite rugby athletes (52.1 ± 10.7) than non-athletes (48.7 ± 10.8). There were more elite rugby athletes (54%) within the upper TGS quartile, and fewer (46%) within the lower quartile, compared to non-athletes (31% and 69%, respectively; P  = 5·10 -5 ), and the TGS was able to distinguish between elite rugby athletes and non-athletes (area under the curve = 0.59; 95% confidence interval 0.55-0.63; P  = 9·10 -7 ). Furthermore, MDR identified a three-SNP model of COL5A1 rs12722, COL5A1 rs3196378 and MIR608 rs4919510 that was best able to predict elite athlete status, with a greater frequency of the CC-CC-CC genotype combination in elite rugby athletes (9.8%) than non-athletes (5.3%). We propose that elite rugby athletes possess "preferable" musculoskeletal soft-tissue injury-associated polygenic profiles that have helped them achieve success in the high injury risk environment of rugby. These data may, in future, have implications for the individual management of musculoskeletal soft-tissue injury. Highlights Elite rugby athletes have preferable polygenic profiles to non-athletes in terms of genetic variants previously associated with musculoskeletal soft-tissue injury.The total genotype score was able to distinguish between elite rugby athletes and non-athletes. COL5A1 rs12722, COL5A1 rs3196378 and MIR608 rs4919510 produced the best model for predicting elite athlete status.We propose that elite rugby athletes may have an inherited advantage to achieving elite status due to an increased resistance to soft-tissue injury.

Published
2023
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39. Gene variants previously associated with reduced soft tissue injury risk: Part 1 - independent associations with elite status in rugby.

Author

Brazier J, Antrobus MR, Herbert AJ, Callus PC, Stebbings GK, Day SH, Heffernan SM, Kilduff LP, Bennett MA, Erskine RM, Raleigh SM, Collins M, Pitsiladis YP, and Williams AG

Subjects
Humans, Male, Female, Adult, Matrix Metalloproteinase 3, Rugby, Alleles, Football, Soft Tissue Injuries genetics, MicroRNAs
Abstract

There is growing evidence of genetic contributions to tendon and ligament pathologies. Given the high incidence and severity of tendon and ligament injuries in elite rugby, we studied whether 13 gene polymorphisms previously associated with tendon/ligament injury were associated with elite athlete status. Participants from the RugbyGene project were 663 elite Caucasian male rugby athletes (RA) (mean (standard deviation) height 1.85 (0.07) m, mass 101 (12) kg, age 29 (7) yr), including 558 rugby union athletes (RU) and 105 rugby league athletes. Non-athletes (NA) were 909 Caucasian men and women (56% female; height 1.70 (0.10) m, mass 72 (13) kg, age 41 (23) yr). Genotypes were determined using TaqMan probes and groups compared using Χ 2 and odds ratio (OR). COLGALT1 rs8090 AA genotype was more frequent in RA (27%) than NA (23%; P  = 0.006). COL3A1 rs1800255 A allele was more frequent in RA (26%) than NA (23%) due to a greater frequency of GA genotype (39% vs 33%). For MIR608 rs4919510, RA had 1.7 times the odds of carrying the CC genotype compared to NA. MMP3 rs591058 TT genotype was less common in RA (25.1%) than NA (31.2%; P  < 0.04). For NID1 rs4660148, RA had 1.6 times the odds of carrying the TT genotype compared to NA. It appears that elite rugby athletes have an inherited advantage that contributes to their elite status, possibly via resistance to soft tissue injury. These data may, in future, assist personalised management of injury risk amongst athletes. Highlights The elite rugby athletes we studied had differing genetic characteristics to non-athletes regarding genetic variants previously associated with soft-tissue injury risk. COLGALT1 rs8090, COL3A1 rs1800255, MIR608 rs4919510, MMP3 rs591058 and NID1 rs4660148 were all associated with elite status in rugby.We propose that elite rugby athletes might possess an inherited resistance to soft tissue injury, which has enabled them to achieve elite status despite exposure to the high-risk environment of elite rugby.

Published
2023
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40. Collagen Gene Polymorphisms Previously Associated with Resistance to Soft-Tissue Injury Are More Common in Competitive Runners Than Nonathletes.

Author

Dines HR, Nixon J, Lockey SJ, Herbert AJ, Kipps C, Pedlar CR, Day SH, Heffernan SM, Antrobus MR, Brazier J, Erskine RM, Stebbings GK, Hall ECR, and Williams AG

Subjects
Male, Humans, Female, Collagen Type V genetics, Genotype, Collagen genetics, Polymorphism, Single Nucleotide, Running, Soft Tissue Injuries
Abstract

Abstract: Dines, HR, Nixon, J, Lockey, SJ, Herbert, AJ, Kipps, C, Pedlar, CR, Day, SH, Heffernan, SM, Antrobus, MR, Brazier, J, Erskine, RM, Stebbings, GK, Hall, ECR, and Williams, AG. Collagen gene polymorphisms previously associated with resistance to soft-tissue injury are more common in competitive runners than nonathletes. J Strength Cond Res 37(4): 799-805, 2023-Single-nucleotide polymorphisms (SNPs) of collagen genes have been associated with soft-tissue injury and running performance. However, their combined contribution to running performance is unknown. We investigated the association of 2 collagen gene SNPs with athlete status and performance in 1,429 Caucasian subjects, including 597 competitive runners (354 men and 243 women) and 832 nonathletes (490 men and 342 women). Genotyping for COL1A1 rs1800012 (C > A) and COL5A1 rs12722 (C > T) SNPs was performed by a real-time polymerase chain reaction. The numbers of "injury-resistant" alleles from each SNP, based on previous literature (rs1800012 A allele and rs12722 C allele), were combined as an injury-resistance score (RScore, 0-4; higher scores indicate injury resistance). Genotype frequencies, individually and combined as an RScore, were compared between cohorts and investigated for associations with performance using official race times. Runners had 1.34 times greater odds of being rs12722 CC homozygotes than nonathletes (19.7% vs. 15.5%, p = 0.020) with no difference in the rs1800012 genotype distribution ( p = 0.659). Fewer runners had an RScore 0 of (18.5% vs. 24.7%) and more had an RScore of 4 (0.6% vs. 0.3%) than nonathletes ( p < 0.001). Competitive performance was not associated with the COL1A1 genotype ( p = 0.933), COL5A1 genotype ( p = 0.613), or RScore ( p = 0.477). Although not associated directly with running performance among competitive runners, a higher combined frequency of injury-resistant COL1A1 rs1800012 A and COL5A1 rs12722 C alleles in competitive runners than nonathletes suggests these SNPs may be advantageous through a mechanism that supports, but does not directly enhance, running performance., (Copyright © 2022 National Strength and Conditioning Association.)

Published
2023
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41. The PPARGC1A Gly482Ser polymorphism is associated with elite long-distance running performance.

Author

Hall ECR, Lockey SJ, Heffernan SM, Herbert AJ, Stebbings GK, Day SH, Collins M, Pitsiladis YP, Erskine RM, and Williams AG

Subjects
Male, Humans, Female, Polymorphism, Genetic, Gene Frequency, Genotype, Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha genetics, Physical Endurance genetics, Running
Abstract

Success in long-distance running relies on multiple factors including oxygen utilisation and lactate metabolism, and genetic associations with athlete status suggest elite competitors are heritably predisposed to superior performance. The Gly allele of the PPARGC1A Gly482Ser rs8192678 polymorphism has been associated with endurance athlete status and favourable aerobic training adaptations. However, the association of this polymorphism with performance amongst long-distance runners remains unclear. Accordingly, this study investigated whether rs8192678 was associated with elite status and competitive performance of long-distance runners. Genomic DNA from 656 Caucasian participants including 288 long-distance runners (201 men, 87 women) and 368 non-athletes (285 men, 83 women) was analysed. Medians of the 10 best UK times (Top10) for 10 km, half-marathon and marathon races were calculated, with all included athletes having personal best (PB) performances within 20% of Top10 (this study's definition of "elite"). Genotype and allele frequencies were compared between athletes and non-athletes, and athlete PB compared between genotypes. There were no differences in genotype frequency between athletes and non-athletes, but athlete Ser allele carriers were 2.5% faster than Gly/Gly homozygotes ( p  = 0.030). This study demonstrates that performance differences between elite long-distance runners are associated with rs8192678 genotype, with the Ser allele appearing to enhance performance.

Published
2023
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42. Concussion-Associated Polygenic Profiles of Elite Male Rugby Athletes.

Author

Antrobus MR, Brazier J, Callus PC, Herbert AJ, Stebbings GK, Khanal P, Day SH, Kilduff LP, Bennett MA, Erskine RM, Raleigh SM, Collins M, Pitsiladis YP, Heffernan SM, and Williams AG

Subjects
Athletes, Humans, Male, Athletic Injuries genetics, Brain Concussion genetics, Multifactorial Inheritance, Rugby injuries
Abstract

Due to the high-velocity collision-based nature of elite rugby league and union, the risk of sustaining a concussion is high. Occurrence of and outcomes following a concussion are probably affected by the interaction of multiple genes in a polygenic manner. This study investigated whether suspected concussion-associated polygenic profiles of elite rugby athletes differed from non-athletes and between rugby union forwards and backs. We hypothesised that a total genotype score (TGS) using eight concussion-associated polymorphisms would be higher in elite rugby athletes than non-athletes, indicating selection for protection against incurring or suffering prolonged effects of, concussion in the relatively high-risk environment of competitive rugby. In addition, multifactor dimensionality reduction was used to identify genetic interactions. Contrary to our hypothesis, TGS did not differ between elite rugby athletes and non-athletes (p ≥ 0.065), nor between rugby union forwards and backs (p = 0.668). Accordingly, the TGS could not discriminate between elite rugby athletes and non-athletes (AUC ~0.5), suggesting that, for the eight polymorphisms investigated, elite rugby athletes do not have a more ‘preferable’ concussion-associated polygenic profile than non-athletes. However, the COMT (rs4680) and MAPT (rs10445337) GC allele combination was more common in rugby athletes (31.7%; p < 0.001) and rugby union athletes (31.8%; p < 0.001) than non-athletes (24.5%). Our results thus suggest a genetic interaction between COMT (rs4680) and MAPT (rs10445337) assists rugby athletes in achieving elite status. These findings need exploration vis-à-vis sport-related concussion injury data and could have implications for the management of inter-individual differences in concussion risk.

Published
2022
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43. Aniseikonia

Author

Stokkermans TJ and Day SH

Abstract

The word aniseikonia derives from the Greek words "an," "is," and "eikon," which mean "not," "equal," and "image," respectively. Aniseikonia occurs when there is a difference in an image's perceived size or shape and is often caused by anisometropia, which is a difference in refractive error. When aniseikonia is caused by anisometropia, it is called optical aniseikonia. Aniseikonia can also be caused by changes in the shape and location of the macula and is then called retinal aniseikonia.  Aniseikonia at a young age can result in amblyopia. Aniseikonia at a later age can cause asthenopia, headache, diplopia, dizziness, nervousness, imbalance, nausea, spectacle intolerance, ocular suppression, and distorted space perception. It is thought that over 0.75% of aniseikonia can start to cause symptoms, that at 1 to 3% definite symptoms are present, and that more than 5% of aniseikonia is incompatible with binocular vision. In many cases, optical aniseikonia is predicted by calculating the difference in spectacle magnification of the right and left spectacle lens. In clinical practice, the rule of thumb that every 0.25 diopter of anisometropia causes about 0.25% to 0.5% of aniseikonia is often used. However, studies have shown that these rules of thumb significantly overestimate aniseikonia and direct measurements are much more accurate.  Aniseikonia can be subdivided into symmetrical and asymmetrical aniseikonia. Symmetrical aniseikonia further subdivides into spherical (overall difference in magnification) and cylindrical (a difference in magnification in one orientation). Asymmetrical aniseikonia is also called distortion and occurs when perceived image size differences are unequal in different parts of the visual field. In the case of prismatic distortion, the difference in image size increases in one direction. In the case of pincushion distortion, the corners of one image are stretched more outward than the other. In the case of barrel distortion, the corners of the image appear squeezed inward. In the case of oblique distortion, one image is rotated relative to the other. Aniseikonia is most accurately measured with an eikonometer, but most clinics do not have one. Many other techniques of measuring aniseikonia exist, some of which require minimal equipment and can be done in a regular eye clinic. All these tests employ different methods to dissociate the two ocular images and have developed a method to compare the shape and size difference of the images perceived by the two eyes. Aniseikonia only occurs when the eyes are being used together and does not occur if vision is suppressed or reduced, as may be the case in alternating strabismus and unilateral amblyopia or ocular disease. Anisometropia also does not cause aniseikonia in specific situations described by Knapp's law. According to Knapp's law, axial anisometropia does not cause aniseikonia when the refractive difference between the eyes is solely due to a difference in the axial length (distance from the cornea to the retina) and when the correcting lens is placed at the anterior focal point of the eye which is about 16 mm in front of the cornea. However, clinical applications of Knapp's law are limited as anisometropia is usually not purely axial. The retina is usually stretched in the eye with the increased axial length (a cause of retinal aniseikonia), and placing a correcting lens at 17 mm in front of the eye is impractical. Aniseikonia is treated with the surgical or medical correction of the underlying cause, optically with refractive surgery, clear lens exchange, secondary intraocular lens (IOL) placement, contact lenses, or via spectacle correction with iseikonic lenses. When this is not possible, occlusion of one eye may be the only alternative., (Copyright © 2022, StatPearls Publishing LLC.)

Published
2022

45. Bone mineral density in high-level endurance runners: Part B-genotype-dependent characteristics.

Author

Herbert AJ, Williams AG, Lockey SJ, Erskine RM, Sale C, Hennis PJ, Day SH, and Stebbings GK

Subjects
Adult, Athletes, Case-Control Studies, Female, Genotype, Humans, Male, Phenotype, Sex Factors, Surveys and Questionnaires, Bone Density genetics, Physical Endurance genetics, Polymorphism, Single Nucleotide, Receptors, Purinergic P2X7 genetics, Running physiology, Wnt Proteins genetics
Abstract

Purpose: Inter-individual variability in bone mineral density (BMD) exists within and between endurance runners and non-athletes, probably in part due to differing genetic profiles. Certainty is lacking, however, regarding which genetic variants may contribute to BMD in endurance runners and if specific genotypes are sensitive to environmental factors, such as mechanical loading via training., Method: Ten single-nucleotide polymorphisms (SNPs) were identified from previous genome-wide and/or candidate gene association studies that have a functional effect on bone physiology. The aims of this study were to investigate (1) associations between genotype at those 10 SNPs and bone phenotypes in high-level endurance runners, and (2) interactions between genotype and athlete status on bone phenotypes., Results: Female runners with P2RX7 rs3751143 AA genotype had 4% higher total-body BMD and 5% higher leg BMD than AC + CC genotypes. Male runners with WNT16 rs3801387 AA genotype had 14% lower lumbar spine BMD than AA genotype non-athletes, whilst AG + GG genotype runners also had 5% higher leg BMD than AG + GG genotype non-athletes., Conclusion: We report novel associations between P2RX7 rs3751143 genotype and BMD in female runners, whilst differences in BMD between male runners and non-athletes with the same WNT16 rs3801387 genotype existed, highlighting a potential genetic interaction with factors common in endurance runners, such as high levels of mechanical loading. These findings contribute to our knowledge of the genetic associations with BMD and improve our understanding of why some runners have lower BMD than others., (© 2021. The Author(s).)

Published
2022
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46. Bone mineral density in high-level endurance runners: part A-site-specific characteristics.

Author

Herbert AJ, Williams AG, Lockey SJ, Erskine RM, Sale C, Hennis PJ, Day SH, and Stebbings GK

Subjects
Absorptiometry, Photon, Adult, Female, Humans, Male, Menstruation physiology, Phenotype, Sex Factors, Bone Density, Physical Endurance physiology, Running physiology
Abstract

Purpose: Physical activity, particularly mechanical loading that results in high-peak force and is multi-directional in nature, increases bone mineral density (BMD). In athletes such as endurance runners, this association is more complex due to other factors such as low energy availability and menstrual dysfunction. Moreover, many studies of athletes have used small sample sizes and/or athletes of varying abilities, making it difficult to compare BMD phenotypes between studies., Method: The primary aim of this study was to compare dual-energy X-ray absorptiometry (DXA) derived bone phenotypes of high-level endurance runners (58 women and 45 men) to non-athletes (60 women and 52 men). Our secondary aim was to examine the influence of menstrual irregularities and sporting activity completed during childhood on these bone phenotypes., Results: Female runners had higher leg (4%) but not total body or lumbar spine BMD than female non-athletes. Male runners had lower lumbar spine (9%) but similar total and leg BMD compared to male non-athletes, suggesting that high levels of site-specific mechanical loading was advantageous for BMD in females only and a potential presence of reduced energy availability in males. Menstrual status in females and the number of sports completed in childhood in males and females had no influence on bone phenotypes within the runners., Conclusion: Given the large variability in BMD in runners and non-athletes, other factors such as variation in genetic make-up alongside mechanical loading probably influence BMD across the adult lifespan., (© 2021. The Author(s).)

Published
2021
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47. Genetic Polymorphisms Related to VO2max Adaptation Are Associated With Elite Rugby Union Status and Competitive Marathon Performance.

Author

Hall ECR, Almeida SS, Heffernan SM, Lockey SJ, Herbert AJ, Callus P, Day SH, Pedlar CR, Kipps C, Collins M, Pitsiladis YP, Bennett MA, Kilduff LP, Stebbings GK, Erskine RM, and Williams AG

Subjects
Athletes, Humans, Male, Marathon Running, Oxygen Consumption genetics, Polymorphism, Genetic, Rugby, Athletic Performance, Running
Abstract

Purpose: Genetic polymorphisms have been associated with the adaptation to training in maximal oxygen uptake (V˙O2max). However, the genotype distribution of selected polymorphisms in athletic cohorts is unknown, with their influence on performance characteristics also undetermined. This study investigated whether the genotype distributions of 3 polymorphisms previously associated with V˙O2max training adaptation are associated with elite athlete status and performance characteristics in runners and rugby athletes, competitors for whom aerobic metabolism is important., Methods: Genomic DNA was collected from 732 men including 165 long-distance runners, 212 elite rugby union athletes, and 355 nonathletes. Genotype and allele frequencies of PRDM1 rs10499043 C/T, GRIN3A rs1535628 G/A, and KCNH8 rs4973706 T/C were compared between athletes and nonathletes. Personal-best marathon times in runners, as well as in-game performance variables and playing position, of rugby athletes were analyzed according to genotype., Results: Runners with PRDM1 T alleles recorded marathon times ∼3 minutes faster than CC homozygotes (02:27:55 [00:07:32] h vs 02:31:03 [00:08:24] h, P = .023). Rugby athletes had 1.57 times greater odds of possessing the KCNH8 TT genotype than nonathletes (65.5% vs 54.7%, χ2 = 6.494, P = .013). No other associations were identified., Conclusions: This study is the first to demonstrate that polymorphisms previously associated with V˙O2max training adaptations in nonathletes are also associated with marathon performance (PRDM1) and elite rugby union status (KCNH8). The genotypes and alleles previously associated with superior endurance-training adaptation appear to be advantageous in long-distance running and achieving elite status in rugby union.

Published
2021
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48. Genetic Factors That Could Affect Concussion Risk in Elite Rugby.

Author

Antrobus MR, Brazier J, Stebbings GK, Day SH, Heffernan SM, Kilduff LP, Erskine RM, and Williams AG

Abstract

Elite rugby league and union have some of the highest reported rates of concussion (mild traumatic brain injury) in professional sport due in part to their full-contact high-velocity collision-based nature. Currently, concussions are the most commonly reported match injury during the tackle for both the ball carrier and the tackler (8-28 concussions per 1000 player match hours) and reports exist of reduced cognitive function and long-term health consequences that can end a playing career and produce continued ill health. Concussion is a complex phenotype, influenced by environmental factors and an individual's genetic predisposition. This article reviews concussion incidence within elite rugby and addresses the biomechanics and pathophysiology of concussion and how genetic predisposition may influence incidence, severity and outcome. Associations have been reported between a variety of genetic variants and traumatic brain injury. However, little effort has been devoted to the study of genetic associations with concussion within elite rugby players. Due to a growing understanding of the molecular characteristics underpinning the pathophysiology of concussion, investigating genetic variation within elite rugby is a viable and worthy proposition. Therefore, we propose from this review that several genetic variants within or near candidate genes of interest, namely APOE , MAPT , IL6R , COMT , SLC6A4 , 5-HTTLPR , DRD2 , DRD4 , ANKK1 , BDNF and GRIN2A , warrant further study within elite rugby and other sports involving high-velocity collisions.

Published
2021
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49. Anthropometric and Physiological Characteristics of Elite Male Rugby Athletes.

Author

Brazier J, Antrobus M, Stebbings GK, Day SH, Callus P, Erskine RM, Bennett MA, Kilduff LP, and Williams AG

Subjects
Athletes, Athletic Performance physiology, Humans, Male, Muscle Strength physiology, Muscle, Skeletal physiology, Body Weights and Measures, Football physiology, Physical Fitness physiology
Abstract

Brazier, J, Antrobus, M, Stebbings, GK, Day, SH, Callus, P, Erskine, RM, Bennett, MA, Kilduff, LP, and Williams, AG. Anthropometric and physiological characteristics of elite male rugby athletes. J Strength Cond Res 34(6): 1790-1801, 2020-This is the first article to review the anthropometric and physiological characteristics required for elite rugby performance within both rugby union (RU) and rugby league (RL). Anthropometric characteristics such as height and body mass, and physiological characteristics such as speed and muscular strength, have previously been advocated as key discriminators of playing level within rugby. This review aimed to identify the key anthropometric and physiological properties required for elite performance in rugby, distinguishing between RU and RL, forwards and backs and competitive levels. There are differences between competitive standards such that, at the elite level, athletes are heaviest (RU forwards ∼111 kg, backs ∼93 kg; RL forwards ∼103 kg, backs ∼90 kg) with lowest % body fat (RU forwards ∼15%, backs ∼12%; RL forwards ∼14%, backs ∼11%), they have most fat-free mass and are strongest (back squat: RU forwards ∼176 kg, backs ∼157 kg; RL forwards ∼188 kg, backs ∼168 kg; bench press: RU forwards ∼131 kg, backs ∼118 kg; RL forwards ∼122 kg, backs ∼113 kg) and fastest (10 m: RU forwards ∼1.87 seconds, backs ∼1.77 seconds; 10 m: RL forwards ∼1.9 seconds, backs ∼1.83 seconds). We also have unpublished data that indicate contemporary RU athletes have less body fat and are stronger and faster than the published data suggest. Regardless, well-developed speed, agility, lower-body power, and strength characteristics are vital for elite performance, probably reflect both environmental (training, diet, etc.) and genetic factors, distinguish between competitive levels, and are therefore important determinants of elite status in rugby.

Published
2020
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50. ACGME International: The First 10 Years.

Author

Day SH and Nasca TJ

Subjects
Accreditation methods, Accreditation standards, Education, Medical, Graduate methods, Education, Medical, Graduate organization & administration, International Agencies, Accreditation organization & administration, Education, Medical, Graduate standards
Published
2019
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