Growth hormone 1 (GH1) gene and performance and post-race rectal temperature during the South African Ironman triathlon

Background

Some studies have suggested that the insertion allele of the ACE gene is associated with endurance performance, including the Ironman triathlon. It is possible that this association is due to genetic linkage between the ACE I/D locus and the T/A variant in intron 4 of the neighbouring GH1 gene. The A variant is associated with lower levels of growth hormone production. Growth hormone has multiple effects, especially on metabolism during exercise and recovery from exercise. Its production during exercise has also been shown to stimulate sweat rate and heat loss.

Objective

To determine whether the GH1 gene is associated with the performance and/or post‐race rectal temperatures of competitors in the South African Ironman triathlon.

Methods

A total of 169 of the fastest finishing white male triathletes who completed the 2000 and/or 2001 South African Ironman triathlon and 155 control subjects were genotyped for the T/A variant in the GH1 gene. Post‐race rectal temperature was also determined in 103 of these triathletes.

Results

There was no significant difference in the frequency of this polymorphism in the GH1 gene when the fastest finishing triathletes were compared with the control subjects. Post‐race rectal temperatures were, however, significantly higher in those triathletes with an AA genotype (mean (SD) 37.7 (0.8)°C) compared with those with a TT genotype (37.2 (0.8)°C) (p  =  0.019).

Conclusions

The T/A polymorphism in intron 4 of the GH1 gene was not associated with performance of the fastest finishers of the South African Ironman triathlon. Post‐race rectal temperatures were, however, significantly higher in the fastest finishing athletes, who were homozygous for a GH1 genotype associated with lower growth hormone production.     

AVPR2 gene and weight changes during triathlons

The arginine vasopressin receptor 2 (AVPR2) plays an important antidiuretic role in regulating water balance to maintain osmotic equilibrium. The aim of this study was to determine if there were any associations between single nucleotide polymorphisms (SNPs), within the AVPR2 gene, and changes in serum sodium concentrations and/or body weight (BW) in Ironman triathletes. Caucasian male triathletes who completed either the 2000, 2001 or 2006 South African Ironman Triathlons were genotyped (n=570) for at least one SNP. Pre- and post-race serum [Na+] (pre n=514; post n=423) and BWs (pre n=556; post n=552) were measured. Triathletes were divided into 3 groups according to their relative BW loss during the triathlon (BW loss of 0-3, 3-5 and >5%). There was a significant linear trend (p=0.010, x2=6.7) for the distribution of minor haplotypes GCT, GTC and GCC across the 3 BW loss groups. The >5% group had the highest percentage (4.7%) of triathletes with minor haplotypes followed by the 3-5% (3.6%) and 3-0% (0%) groups. In conclusion, the minor haplotype constructs of AVPR2 SNPs were associated with larger BW losses during the Ironman Triathlons. This finding supports a possible genetic contribution to BW loss during endurance exercise events acting through the argine vasopression system.     

The -55 C/T polymorphism within the UCP3 gene and performance during the South African Ironman Triathlon

Uncoupling protein 3 is believed to be involved in total body energy expenditure, including the regulation of fat and glucose metabolism. These biochemical processes may distinguish top ultra-endurance triathletes from slower competitors. The aim of this study was to determine whether the uncoupling protein 3 gene is associated with the performance capacity of ultra-endurance Ironman triathletes. Two triathlete groups consisting of the 89 fastest and 89 slowest Caucasian, male triathletes who completed either the 2000 or 2001 South African Ironman triathlon events were genotyped for the -55 C/T polymorphism within the uncoupling protein 3 gene. A control group consisting of 92 Caucasian males who had not trained for or participated in an ultra-endurance athletic event was also genotyped. There was no significant difference in the genotype (CC, CT and TT) frequency distribution of the -55 C/T polymorphism within the uncoupling protein 3 gene between the fast triathlete, slow triathlete and control groups. In addition, no significant differences were observed between the frequencies of the C and T alleles between the three groups. The two triathlete groups were combined and grouped according to their genotype. No particular genotype or allele was associated with the time taken by the triathletes to complete the entire triathlon, or either the swim, cycle or run legs of the event. Thus no association was found between the -55 C/T polymorphism within the uncoupling protein 3 gene and the ultra-endurance performance of triathletes who completed either the 2000 or 2001 South African Ironman triathlons.     

The angiotensin converting enzyme I/D polymorphism in long distance runners

AIM: There is an assumption that ACE I/D polymorphism represents one of the possible genetic factors that might be associated with sports excellence. Recent studies have identified an increased frequency of I allele in elite endurance athletes, long distance runners, rowers and mountaineers. The aim of this study was to test the hypothesis that the ACE I/D polymorphism is associated with enhanced endurance performance. METHODS: We examined this hypothesis by determining ACE I/D allele frequency in 215 marathon runners, 222 half-marathon runners and 18 inline skaters classified by performance (marathon competition results). ACE genotype and allele frequencies were compared with 252 healthy controls. RESULTS: ACE genotype frequency in the whole cohort did not differ from that in the sedentary controls (P < 0.56). However, there was an increase of the I/I genotype incidence amongst successful marathon runners scoring on places from 1st to 150th (P < 0.01). These findings were confirmed in the group of inline skaters, similarly demonstrating an increase of the I/I genotype (P < 0.01). There was no association found between half marathon runners and the ACE genotype (P < 0.59). CONCLUSIONS: An excess of the I allele in long distance runners confirms the association between the ACE I/D polymorphism and endurance sports performance.     

COL6A1 gene and Ironman triathlon performance

Mutations in the type VI collagen gene ( COL6A1) cause myopathy and muscle weakness. In addition, COL6A1 knockout mice were shown to have impaired running performance and reduced muscle strength. The COL6A1 rs35796750 polymorphism (IVS32-29 T/C) has been associated with complex phenotypes. The aim of this study was therefore to determine if this polymorphism is associated with performance during the 226?km Ironman triathlon. Participants (n=661) were recruited during 4 South African Ironman triathlons. Finishing times for the 3.8?km swim, 180?km bike, 42.2?km run, and overall race were provided by the race organisers. All participants were genotyped for the COL6A1 rs35796750 polymorphism. Participants with the COL6A1 TT genotype were significantly faster during the bike (p=0.014) and overall race (p=0.030). When participants were grouped into fast, middle and slow bike finishing time tertiles, there was a significant linear trend for the TT genotype (Fast: TT=35.7%; Middle: TT=29.0%; Slow: TT=23.8%; p=0.008). No significant genotype frequency differences were observed for the swim or run of the triathlon. In conclusion, the COL6A1 gene is therefore a potential marker for endurance cycling performance. These effects may be mediated through changes to the composition of type VI collagen containing tissues, such as muscle and tendon.     

The influence of angiotensin-converting enzyme gene ID polymorphism on human physical fitness performance in European and other populations

Angiotensin-converting enzyme (ACE) is a component of the circulating renin–angiotensin system, which influences circulatory homeostasis through the degradation of vasodilator kinins and the generation of vasopressor angiotensin II. Various phenotypic characteristics such as diseases and human performances could be associated with genetic polymorphisms within the ACE gene. To date, one of the most well-studied genetic polymorphisms that has been shown to be associated with athletic performance is that of the ACE gene. Previous studies investigating the influences of polymorphisms and various phenotypic characteristics have produced inconsistent findings due to inter-ethnic variations in the distribution of the different ACE alleles. For example, some studies showed that the I allele was associated with fatigue resistance in skeletal muscle and endurance performance while the D allele had been associated with power or sprint performance. Nevertheless, controversy still exists regarding the above conclusion as related studies reported that the I allele was associated with a better power or sprint performance rather than with athletic endurance abilities. This article discusses the inter-ethnic variations of the distribution of the different ACE alleles in several ethnic groups such as in European, African, American, and Asian populations. Additionally, the influences of the ACE ID polymorphism on human physical fitness performances in European and other populations are discussed.     

飞行员血管紧张素转换酶基因插入/缺失多态性及其血清水平的研究

目的了解飞行员血管紧张素转换酶(ACE)基因插入/缺失（I/D）多态性及其血清水平,探讨ACE基因多态性与飞行员耐力可能的关系。方法飞行员118例,健康对照者96例,用聚合酶链反应（PCR）扩增技术检测ACE基因I/D多态性,用比色法测定血清ACE水平。结果位于ACE基因第16内含子的I/D多态性经PCR扩增后呈三种基因型纯合子插入型（II）、纯合子缺失型（DD）和杂合子插入/缺失型（I/D）。飞行员组II基因型（44.07%）和Ⅰ等位基因频率（0.65）显著高于健康对照组(分别为31.25%和0.52)。ACE基因多态性与血清ACE水平明显相关(DD>ID,DD>II)。结论ACEⅠ基因有可能在飞行员的飞行耐力中起重要作用。     

Is there an association between ACE and CKMM polymorphisms and cycling performance status during 3-week races?

In this paper, we examine the association between polymorphisms of the angiotensin-converting enzyme (ACE) and muscle-specific creatine kinase (CKMM) genes, and the actual performance status observed in professional cyclists capable of completing a classic tour stage race such as the Giro d'Italia, Tour de France, or Vuelta a Espa?a. To accomplish this, we compared the frequencies of the ACE and CKMM genotypes/alleles in 50 top-level Spanish professional cyclists that have completed at least one of these events to 119 sedentary controls, and 27 elite (Olympic-class) Spanish runners. The genetic polymorphism at the CK-MM locus was detected with the NcoI restriction endonuclease. The results of our study showed that the proportion of the DD genotype was higher in cyclists (50.0 %) than in the other two groups (p<0.05), the proportion of the ID genotype was higher in controls (46.2 %) than in the other two groups (p<0.05), and the proportion of the II genotype was higher in runners (40.7 %) than in the other two groups (p<0.05). The proportion of the D allele was higher in both cyclists (65.0 %) and controls (57.6 %) than in runners (46.3 %) (p<0.001), whereas the proportion of the I allele was higher in runners than in the other two groups (p<0.001). No statistical differences were found for CKK-MM- NcoI. We conclude that in top-level professional cyclists capable of completing a classic 3-wk tour race, the frequency distribution of the D allele and the DD genotype seems to be higher than in other endurance athletes such as elite runners (in whom the I allele is especially frequent).     

ACE I/D gene polymorphism and aerobic endurance development in response to training in a non-elite female cohort

AIM: The aim of this study was to investigate the association between ACE gene polymorphism and short- and medium-duration aerobic endurance performance improvements in response to the same training regimen in a non-elite female cohort. METHODS: Fifty-five female non-elite Caucasian Turkish athletes trained to enhance running speeds corresponding to 70% and 90% of heart rate reserve (V-HRR70 and V-HRR90 respectively) 30 min running speed performance (V-30min) 3 times per week, for 6 weeks. ACE gene polymorphisms studied by PCR analysis. RESULTS: The distribution of genotypes in the whole cohort was 21.8%, 41.8%, 36.4% for II (n=12), ID (n=23) and DD (n=20), respectively. Subjects with ACE II genotype had significantly higher improvements in V-30min and V-HRR70 than the ACE DD group (P<0.05). However, in HRR90 ACE DD genotype had a better performance enhancement in running speed than others (P<0.05). Endurance improvements in the V-HRR70 and in the V-30min showed a linear trend as II>ID>DD (P<0.05 and P<0.01, respectively) while a linear trend as DD>ID>II (P<0.01) observed in V-HRR90. CONCLUSION: ACE II genotype may related with better improvements in medium duration aerobic endurance performance whilst ACE DD genotype seems to be more advantageous in performance enhancement in shorter duration and higher intensity endurance activities.     

ACE gene polymorphism and erythropoietin in endurance athletes at moderate altitude

PURPOSE: To determine the role of the ACE (I/D) gene polymorphism on erythropoietic response in endurance athletes after natural exposure to moderate altitude. METHODS: Erythropoietic activity was measured in 63 male endurance athletes following natural exposure to moderate altitude (2200 m) during 48 h. Erythropoietin (EPO) levels and hemoglobin (Hb) concentrations were measured at baseline and 12, 24, and 48 h after reaching the set altitude. Reticulocyte counts were determined at baseline and 48 h thereafter. Subjects were grouped into two groups (responders and nonresponders) based on significant increase in EPO levels (median: > 16.5 ng x m(-1)) after 24 h at altitude. ACE gene polymorphism was ascertained by polymerase chain reaction (DD, 31 (49%); ID, 24 (38%); II, 8 (13%)). RESULTS: Overall, EPO levels significantly increased at 12 (70%; P = 0.0001) and 24 h (72%; P = 0.0001) above baseline concentration following exposure to 2200 m. Thereafter, EPO concentration decreased at 48 h, but a significant increase in Hb levels (4.6 +/- 4%; P = 0.0001) and reticulocyte count (50.5 +/- 79%; P = 0.0001) was observed at the end of the experiment, suggesting negative feedback. There were no significant differences in EPO and Hb concentration profiles between subjects with DD genotype and those with other genotypes (ID/II). Moreover, responders (N = 42; DD, 50%; ID/II, 50%) and nonresponders (N = 21; DD, 48%; ID/II, 52%) showed a similar erythropoietic profile during the experiment and the ACE gene polymorphism did not influence the time course of the erythropoietic response. CONCLUSIONS: The ACE gene polymorphism does not influence erythropoietic activity in endurance athletes after short-term exposure to moderate altitude.     

Master triathletes have not reached limits in their Ironman triathlon performance

The purpose of this study was to analyze the participation and performance trends of male triathletes in the “Ironman Switzerland” from 1995 to 2010. Participation trends of all finishers aged between 18 and 64 years were analyzed over the 16‐year period by considering four 4‐year periods 1995–1998, 1999–2002, 2003–2006, and 2007–2010, respectively. The 3.8‐km swimming, 180‐km cycling, 42‐km running times, and total race times were analyzed for the top 10 triathletes in each age group from 18 to 64 years. The participation of master triathletes (≥40 years old) increased over the years, representing on average 23%, 28%, 37%, and 48% of total male finishers during the four 4‐year periods, respectively. Over the 1995–2010 period, triathletes older than 40 years significantly improved their performance in swimming, cycling, running, and in the total time taken to complete the race. The question whether master Ironman triathletes have yet reached limits in their performance during Ironman triathlon should be raised. Further studies investigating training regimes, competition experience, or socio‐demographic factors are needed to gain better insights into the phenomenon of the relative improvement in ultra‐endurance performance with advancing age.     

Human performance: a role for the ACE genotype?

The I allele of the angiotensin I-converting enzyme (ACE) gene is associated with lower ACE activity and endurance performance; an excess occurs in elite distance runners, rowers, and mountaineers, perhaps secondary to enhanced muscle efficiency. Conversely, the D allele is associated with training-related strength gain and elite power-oriented performance secondary to increased ACE and angiotensin II, a growth factor.     

血管紧张素转换酶基因多态性与房颤心肌纤维化的相关性研究

目的：研究血管紧张素转换酶基因（ACE）插入／缺失多态性与心肌纤维化及心房纤颤的相关性，以寻找心房纤颤发病的分子机制。方法：选择50例房颤患者（房颤组）及43例非房颤者（对照组），用PCR方法检测两组ACE基因插入／缺失多态性；用ELISA法测定心肌纤维化的指标（Ⅰ型前胶原羧基端肽、Ⅲ型前胶原氨基端肽）．比较不同基因型、不同等位基因的分布及Ⅰ型前胶原羧基端肽（PIP）和Ⅲ型前胶原氨基端肽（PⅢP）的血清浓度。结果：房颤组与对照组ACEI／D多态性缺失纯合型（DD型）、杂合子（DⅠ型）、插入纯合型（Ⅱ型）基因型频率分别为34％、40％、26％和18．6％、41．9％、39．5％；房颤组与对照组D等位基因、Ⅰ等位基因分布频率为54％、46％和39．5％、60．5％；对不同基因型分布比较发现：D等位基因分布频率在房颤组中较对照组明显增大（P〈0．05）；房颤组PIP、PⅢP浓度明显高于对照组（P〈0．05）；在不同基因型之间PIP、PⅢP浓度比较中发现，DD基因型PIP、PⅢP浓度显著高于DⅠ型和Ⅱ型（P〈0．05）。结论：D等位基因可能是房颤的易患基因；房颤患者心肌纤维化指标PIP、PⅢP显著升高；ACEDD基因型可能是心肌纤维化及心脏重构的危险因素。     

The ACE gene and human performance: 12 years on

Some 12 years ago, a polymorphism of the angiotensin I-converting enzyme (ACE) gene became the first genetic element shown to impact substantially on human physical performance. The renin-angiotensin system (RAS) exists not just as an endocrine regulator, but also within local tissue and cells, where it serves a variety of functions. Functional genetic polymorphic variants have been identified for most components of RAS, of which the best known and studied is a polymorphism of the ACE gene. The ACE insertion/deletion (I/D) polymorphism has been associated with improvements in performance and exercise duration in a variety of populations. The I allele has been consistently demonstrated to be associated with endurance-orientated events, notably, in triathlons. Meanwhile, the D allele is associated with strength- and power-orientated performance, and has been found in significant excess among elite swimmers. Exceptions to these associations do exist, and are discussed. In theory, associations with ACE genotype may be due to functional variants in nearby loci, and/or related genetic polymorphism such as the angiotensin receptor, growth hormone and bradykinin genes. Studies of growth hormone gene variants have not shown significant associations with performance in studies involving both triathletes and military recruits. The angiotensin type-1 receptor has two functional polymorphisms that have not been shown to be associated with performance, although studies of hypoxic ascent have yielded conflicting results. ACE genotype influences bradykinin levels, and a common gene variant in the bradykinin 2 receptor exists. The high kinin activity haplotye has been associated with increased endurance performance at an Olympic level, and similar results of metabolic efficiency have been demonstrated in triathletes. Whilst the ACE genotype is associated with overall performance ability, at a single organ level, the ACE genotype and related polymorphism have significant associations. In cardiac muscle, ACE genotype has associations with left ventricular mass changes in response to stimulus, in both the health and diseased states. The D allele is associated with an exaggerated response to training, and the I allele with the lowest cardiac growth response. In light of the I-allele association with endurance performance, it seems likely that other regulatory mechanisms exist. Similarly in skeletal muscle, the D allele is associated with greater strength gains in response to training, in both healthy individuals and chronic disease states. As in overall performance, those genetic polymorphisms related to the ACE genotype, such as the bradykinin 2 gene, also influence skeletal muscle strength. Finally, the ACE genotype may influence metabolic efficiency, and elite mountaineers have demonstrated an excess of I alleles and I/I genotype frequency in comparison to controls. Interestingly, this was not seen in amateur climbers. Corroboratory evidence exists among high-altitude settlements in both South America and India, where the I allele exists in greater frequency in those who migrated from the lowlands. Unfortunately, if the ACE genotype does influence metabolic efficiency, associations with peak maximal oxygen consumption have yet to be rigorously demonstrated. The ACE genotype is an important but single factor in the determinant of sporting phenotype. Much of the mechanisms underlying this remain unexplored despite 12 years of research.     

Maintenance of plasma volume and serum sodium concentration despite body weight loss in ironman triathletes.

OBJECTIVE: To examine the relationship between body weight, plasma volume, and serum sodium concentration ([Na]) during prolonged endurance exercise. DESIGN: Observational field study. SETTINGS: 2000 South African Ironman Triathlon. PARTICIPANTS: 181 male triathletes competing in an Ironman triathlon. MAIN OUTCOME MEASURES: Body weight, plasma volume, and serum ([Na]) change from pre- to postrace. RESULTS: Significant body weight loss occurred (-4.9 +/- 1.7%; P < 0.0001), while both plasma volume (1.0 +/- 11.2%; P = 0.4: NS) and serum [Na] (0.6 +/- 2.4%; P < 0.001) increased from pre- to postrace. Blood volume (-0.6 +/- 6.6%) and red cell volume (-2.6 +/- 5.5%; P < 0.001) decreased in conjunction with the body weight loss. There was a strong correlation between blood and plasma volume change, both as a percentage, and absolute change in fluid volume (r = 0.9; P < 0.001). Body weight change was positively correlated with plasma volume change (r = -0.4; P < 0.001), but inversely correlated with serum [Na] change (r = -0.4; P < 0.001). Plasma volume change was not significantly correlated with serum [Na] change (r = 0.0; NS). Serum [Na] change was inversely correlated with both percentage of red cell volume change (r = -0.2; P < 0.05) and percentage body weight change (r = -0.4; P < 0.001). CONCLUSION: Plasma volume and serum [Na] were maintained in male Ironman triathletes, despite significant (5%) body weight loss during the course of the race. Body weight was not an accurate "absolute" surrogate of fluid balance homeostasis during prolonged endurance exercise. Clinicians should be warned against viewing these three regulatory parameters as interchangeable during an Ironman triathlon.     

The dipsomania of great distance: water intoxication in an Ironman triathlete

Of 371 athletes (62% of all finishers) whose weights were measured before and after the 226 km South African Ironman Triathlon, the athlete who gained the most weight (3.6 kg) during the race was the only competitor to develop symptomatic hyponatraemia. During recovery, he excreted an excess of 4.6 litres of urine. This case report again confirms that symptomatic hyponatraemia is caused by considerable fluid overload independent of appreciable NaCl losses. Hence prevention of the condition requires that athletes be warned not to drink excessively large volumes of fluid (dipsomania) during very prolonged exercise. This case report also shows that there is a delayed diuresis in this condition and that it is not caused by renal failure.     

No association between ACE I/D polymorphism and cardiovascular hemodynamics during exercise in young women

The ACE I/D polymorphism has been shown to interact with habitual physical activity levels in postmenopausal women to associate with submaximal and with maximal exercise hemodynamics. This investigation was designed to assess the potential relationships between ACE genotype and oxygen consumption (VO2), cardiac output (Q), stroke volume (SV), heart rate (HR), blood pressure (BP), total peripheral resistance (TPR), and arteriovenous oxygen difference ([a-v]O2 diff) during submaximal and maximal exercise in young sedentary and endurance-trained women. Seventy-seven 18-35-yr-old women underwent a maximal exercise test and a number of cardiac output tests on a treadmill using the acetylene rebreathing technique. ACE genotype was not significantly associated with VO2max (II 41.4+/-1.2, ID 39.8+/-0.9, DD 39.8+/-1.1 ml/kg/min, p=ns) or maximal HR (II 191+/-2, ID 191+/-1, DD 193+/-2 bpm, p=ns). In addition, systolic and diastolic BP, (a-v)O2 diff, TPR, SV, and Q during maximal exercise were not significantly associated with ACE genotype. During submaximal exercise, SBP, Q, SV, HR, TPR, and (a-v)O2 diff were not significantly associated with ACE genotype. However, the association between diastolic BP during submaximal exercise and ACE genotype approached significance (p=0.08). In addition, there were no statistically significant interactions between ACE genotype and habitual physical activity (PA) levels for any of the submaximal or the maximal exercise hemodynamic variables. We conclude that the ACE I/D polymorphism was not associated, independently or interacting with habitual PA levels, submaximal, or maximal cardiovascular hemodynamics in young women.     

上海地区汉族优秀游泳运动员ACE基因I/D多态性研究

目的:探讨上海地区汉族不同水平优秀游泳运动员ACE(血管紧张素转化酶)基因I/D多态性的分布特点。方法:采用PCR方法,对上海地区85名汉族优秀游泳运动员和90名汉族普通人的ACE基因I/D多态性进行检测。结果显示,上海地区汉族优秀游泳运动员的ACE基因的基因型和等位基因频率与上海和成都地区汉族普通人无明显差异(P>0.05);上海地区汉族游泳运动员和普通人以及成都地区汉族普通人的基因型和等位基因频率均与高加索人群存在高度显著性差异(P<0.0001),表现出明显的种族差异性。7名上海地区汉族国际健将ACE基因均为II型,运动水平越高的组别,II基因型和I等位基因频率越高,提示具有II基因型或I等位基因频率高的运动员经过多年运动训练,具有成为优秀运动员的可能,特别是II基因型的运动员可能性更大。     

A polymorphism in the alpha2a-adrenoceptor gene and endurance athlete status

PURPOSE: In a case control study, we examined the allelic frequencies and genotype distributions of two restricted fragment length polymorphisms (RFLP) in the alpha-2A-adrenoceptor gene (ADRA2A) and beta-2-adrenoceptor gene (ADRB2) among elite endurance athletes (EEA) and sedentary controls (SC). METHODS: The EEA group included 148 Caucasian male subjects recruited on the basis that they had a VO2max > 74 mL O2 x kg(-1) x min(-1). The SC group comprised 149 unrelated sedentary male subjects, all Caucasians, from the Quebec Family Study. After digestion with the restriction enzymes Dra I (ADRA2A) and Ban I (ADRB2), Southern blotting and hybridization techniques were used to detect the mutations in the two ADR genes, which are encoded on chromosomes 10 (q24-26) and 5 (q31-32), respectively. RESULTS: For the Dra I ADRA2A RFLP, we observed a significant difference in genotype distributions between the two groups (P = 0.037). A higher frequency of the 6.7-kb allele was observed in the EEA group compared with the SC group (P = 0.013). No statistically significant difference was found between groups for the Ban I ADRB2 polymorphic site. Genotype frequencies for both genes in both groups were in Hardy-Weinberg equilibrium. CONCLUSIONS: In summary, we found evidence that ADRA2A gene variability detected with Dra I is weakly associated with elite endurance athlete status, and we conclude that genetic variation in the ADRA2A gene or a locus in close proximity may play a role in being able to sustain the endurance training regimen necessary to attain a high level of maximal aerobic power.     

ACE I/D polymorphism and cardiac adaptations in adolescent athletes

PURPOSE: The aim of this cross-sectional study was to determine whether there is a correlation between left ventricular hypertrophy (LVH) and angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism in adolescent athletes. METHODS: Seventy-five competitive soccer players (aged 15 +/- 1.2 yr) and 52 untrained control subjects (aged 15 +/- 1.6 yr) were examined with echocardiography (echo) and bioelectrical impedance analysis. The ACE genotype of all subjects was determined by PCR and correlated with left ventricular mass (LVM) indices. RESULTS: Allele frequencies were comparable between athletes and controls. Body surface area (BSA), fat-free mass (FFM), and all mean echo measurements were significantly greater in athletes than in controls. LVM and LVM indices for both BSA and FFM were all significantly greater in athletes than in controls (LVM 195.3 +/- 32 g vs 165.3 +/- 37.6 g; LVM/BSA 115.5 +/- 18.9 g x mq(-1) vs 95 +/- 18.2 g x mq(-1); LVM/FFM 3.5 +/- 0.5 vs 3 +/- 0.54, P < 0.001 for the three variables). Left ventricular hypertrophy was found in 17 (23%) athletes. There was no correlation between ACE I/D polymorphism and athletes with LVH as the II and DD genotype frequencies were identical (41%). However, in athletes with LVH, the presence of the D allele was associated with a greater LVM index than compared to homozygous II genotype (LVM = 145 +/- 7.6 g x mq(-1) in DD+ID group vs 135 +/- 2.9 g x mq(-1) in II group, P = 0.008). CONCLUSIONS: The results of the study show that significant changes occur in cardiac morphology and function in adolescent athletes. Interestingly, the ACE I/D polymorphism was associated with the degree of cardiac hypertrophy but not with the occurrence of LVH itself.