The effect of methylphenidate on the dopamine and growth hormone response to exercise in children with attention-deficit hyperactivity disorder.

PURPOSE: To assess the growth hormone (GH) and Dopamine (DA) response to exercise in children with attention-deficit hyperactivity disorder (ADHD) with and without methylphenidate (MP). We hypothesized that the GH and DA response to the exercise with MP would be siginicantly lower. METHODS: Twenty children participated in the study (12 males and 8 females, age range 9-13 years). Ten with ADHD and 10 controls. Participants with ADHD performed an exercise test twice, with and without MP while controls performed one exercise test. Blood samples for GH and DA were collected before, at peak, 30 and 60 min after the end of exercise. RESULTS: Compared to controls, children with ADHD with and without MP, had a significantly lower GH (P < .002) and DA (P < .01) responses to exercise. In participants with ADHD, a significantly greater GH response (p < .04) to exercise was found when MP administered to the children before exercise, yet this response was still significantly lower than controls. CONCLUSIONS: GH and DA excretion after an exercise challenge in children with ADHD is impaired. MP slightly attenuates the GH blunted response. This may link ADHD with growth impairment in some children and explain previous findings indicating that the final adult height is usually not compromised in children with ADHD treated with MP. The combined exercise and stimulant treatment therapeutic effects needs to be further explored. TRIAL REGISTRATION NUMBER: NCT00945971.

IGF1 Genetic Polymorphism and the Association between Vitamin D Status and BMI Percentiles in Children.

Both the IGF1 axis and hypovitaminosis D play a role in childhood obesity, either as a cause or a causality. While some studies suggest an interrelation between vitamin D status, IGF1, and obesity, this mechanism remains obscure. The aim of this study, therefore, was to explore associations between four genetic polymorphisms in the IGF1 axis in hypovitaminosis D-related obesity. The study included 116 pre-pubertal Israeli Arab children (52 girls), mean age 9.4 ± 2.6. Serum 25(OH)D was measured and anthropometric measures were obtained. Genomic DNA was extracted from peripheral EDTA-treated anti-coagulated blood using a standard protocol. Genotypes were determined using the Taqman allelic discrimination assay. The IGF genetic score was computed according to the additive genetic score model. A moderate-to-high negative correlation (r = 0.580, p < 0.05) was seen between the vitamin D status and body mass index (BMI) percentile of participants with high GS. Yet, no correlations were seen between vitamin D status and BMI percentile for participants with a low-to-moderate genetic score (GS) (GS ≤ 2). These results suggest that IGF1 genetic scores associated with elevated circulating IGF1 may indicate a tendency toward developing hypovitaminosis D-associated obesity.

The Genetic Basis of Decathlon Performance: An Exploratory Study.

ABSTRACT: Remmel, L, Ben-Zaken, S, Meckel, Y, Nemet, D, Eliakim, A, and Jürimäe, J. The genetic basis of decathlon performance: an exploratory study. J Strength Cond Res 37(8): 1660-1666, 2023-Decathlon is a combined track and field competition consisting of 10 different events, most of which are anaerobic-type events. Therefore, it is assumed that an anaerobic genetic predisposition might be prevalent among decathletes. Yet, to the best of our knowledge, the genetic basis of decathlon performance had not been studied. Therefore, the aim of this study was to assess the prevalence genetic polymorphisms associated with power performance (AGT, rs699, Met235Thr T/C), speed (ACTN3, rs1815739 C1747T), aerobic endurance (PPARD, rs2016520 T294C), and lactate clearance (MCT1, rs1049434 A1470T) among decathletes. One hundred thirty-seven male track and field athletes (51 sprinters and jumpers, 59 long distance runners, and 27 decathletes) participated in the study. Genomic DNA was extracted from buccal epithelial cells. Genotypes were determined using the Taqman allelic discrimination assay. Decathletes had a higher prevalence of the ACTN3 RR genotype, which is associated with speed ability, and a lower prevalence of the PPARD CC genotype, which is associated with endurance performance compared with long-distance runners. Decathletes had a higher prevalence of the AGT CC genotype associated with strength performance and a higher prevalence of the MCT1 TT genotype, which is associated with improved lactate transport compared with both sprinters and jumpers and long-distance runners. The results suggest that a favorable genetic polymorphism for strength-related capability might be advantageous for decathletes, whereas a genetic makeup favoring aerobic performance is not necessary.

Reduced exercise-induced growth hormone secretion among children with attention-deficit hyperactivity disorder.

PURPOSE: Attention-deficit/hyperactivity disorder (ADHD) is typically a chronic, often lifelong condition. Data suggest that ADHD itself and its treatment may be associated with dysregulated growth, including height and BMI. The reason for this association is yet unknown. The objective of this study was to examine differences in growth hormone (GH) response to exercise between children who had received a diagnosis of ADHD and age- and gender-matched controls. We reasoned that the normal increase in circulating GH seen in response to exercise would be blunted in children with ADHD. METHODS: We recruited 13 treatment-naïve children with newly diagnosed ADHD and 14 age-matched controls (all male) and measured GH response to an exercise test in which the work was scaled to each subject's physical capability. RESULTS: There was no difference in the peak heart rate achieved during exercise between controls and ADHD participants (196.6 ± 1.5 vs. 196.5 ± 2.1 bpm, respectively) and lactate response to exercise (53.8 ± 5.0 vs. 47.9 ± 3.8 mg/dl, respectively). After exercise, GH increased significantly in the control subjects (p < 0.005), while GH responses were substantially blunted in the ADHD group (p = NS) even though the work performed did not differ from controls. CONCLUSIONS: Our data suggest that GH excretion after exercise challenge in children with ADHD is impaired. This can be detected using a minimally invasive, nonpharmacologic challenge and may link ADHD with growth impairment in some children. TRIAL REGISTRATION NUMBER: NCT00945971.

The prevalence of IGF-I axis genetic polymorphisms among decathlon athletes.

OBJECTIVE: Decathlon is a combined track and field competition, consisting of ten, mainly anaerobic events. Insulin-like growth factor-I (IGF1) axis plays a pivotal role in athletes' structural and functional muscle adaptation to exercise training, and in their competitive performance. Based on the great demand for speed physiological characteristics among decathlon athletes, the aim of this study was to assess the prevalence of IGF genetic polymorphisms among decathletes, to present an optimal genetic profile for enhancing performance. METHODS: The participants included 151 male athletes and 75 male non-athletic controls from Israel and Estonia. Athletes were divided into four groups, according to the field of expertise: (a) 40 sprinters and long jumpers; (b) 40 middle distance runners; (c) 44 Weightlifters; and (d) 27 decathletes. Genomic DNA was extracted from the participants' buccal epithelial cells using standard protocol and then analyzed for IGF1 axis related genetic polymorphism using the allelic discrimination assay. RESULTS: A significantly higher prevalence of the IGF1 rs35767 TT genotype was found among decathletes compared to the other athletes, as well as a lower prevalence of the IGF1 rs7136446 GG genotype, a higher prevalence of the IGF1R rs1464430 AA genotype, and a higher prevalence of the IGF2 rs680 GG genotype. Moreover, among the decathletes, carriers of the IGF1 rs7136446 GG genotype achieved higher decathlon scores compared to A-allele carriers. CONCLUSIONS: The findings of this study suggest a potential beneficial role for some IGF-axis polymorphisms (mainly the IGF1 1245 TT and the IGF2 GG) among decathletes, both of which are associated with improved speed performance.

Common genetic basis of ALS patients and soccer players may contribute to disease risk.

OBJECTIVE: The aim of the present study was to determine the prevalence of the ACSL A/G single nucleotide polymorphism among athletes and patients with amyotrophic lateral sclerosis (ALS). ALS is a progressive neurodegenerative disorder of motor neurons that leads to paralysis and death usually within 3-5 years from onset. Previous epidemiological studies reported a higher risk of ALS among soccer players. The ACSL (long-chain-fatty-acid-CoA ligase 1) gene codes the long-chain fatty-acid-coenzyme A ligase family that plays a key role in lipid biosynthesis and fatty acid oxidation. The ACSL A/G polymorphism is associated with endurance trainability. METHODS: One hundred and seventy-eight ALS patients, 172 athletes (60 soccer players, 112 middle- and long-distance runners), and 111 nonathletic controls participated in the study. Genomic DNA was extracted from blood or buccal cells according to the salting-out procedure. Genotypes were determined using the TaqMan allelic discrimination assay. RESULTS: The prevalence of the ACSL AA genotype was significantly higher among soccer players (35.0%) and ALS patients (39.3%) compared to runners (16.1%) and controls (18.0%). However, ALS GG carriers had a higher mortality rate. CONCLUSION: We postulate that soccer players and ALS patients carry a common genetic predisposition that is related to impaired fatty acid utilization. Moreover, while the A allele might be associated with a genetic predisposition toward ALS, especially among soccer players, the G allele might be associated with disease severity. Further research is needed in order to explore the role of the ACSL rs6552828 polymorphism in ALS.

Genetic characteristics of competitive swimmers: a review.

A successful swimming performance is a multi-factorial accomplishment, resulting from a complex interaction of physical, biomechanical, physiological and psychological factors, all of which are strongly affected by the special medium of water as well as by genetic factors. The nature of competitive swimming is unique, as most of the competitive events last less than four minutes. Yet training regimens have an endurance nature (many hours and many kilometres of swimming every day), which makes it impossible to classify swimming by definitions of aerobic-type or anaerobic-type events, as in track and field sports. Therefore, genetic variants associated with swimming performance are not necessarily related to metabolic pathways, but rather to blood lactate transport (MCT1), muscle functioning (IGF1 axis), muscle damage (IL6) and others. The current paper reviews the main findings on the leading 12 genetic polymorphisms (located in the ACE, ACTN3, AMPD1, BDKRB2, IGF1, IL6, MCT1, MSTN, NOS3, PPARA, PPARGC1A, and VEGFR2 genes) related to swimming performance, while taking into consideration the unique environment of this sport.

Insulin-like Growth Factor Axis Genetic Score and Sports Excellence.

ABSTRACT: Ben-Zaken, S, Meckel, Y, Nemet, D, and Eliakim, A. Insulin-like growth factor axis genetic score and sports excellence. J Strength Cond Res 35(9): 2421-2426, 2021-It has been suggested that IGF1 polymorphisms associated with circulating IGF1 levels may be linked to elite short-distance running performance. This study assessed genetic score based on 6 polymorphisms related to the Insulin-like growth factor axis (rs7136446, rs35767, rs6220, rs680, rs2854744, and rs1805086) among elite Israeli runners and swimmers. One hundred sixty-one track and field athletes (123 men and 38 women, age 17-50 years) and 94 swimmers (61 men and 33 women, age 16-49 years) participated in the study. Athletes were divided into short-distance runners (SDRs, major event: 100-200-m sprints and jumps, n = 63) and long-distance runners (LDRs, major event: 5,000 m and marathon, n = 98). Swimmers were divided into short-distance swimmers (SDSs, major event: 50-100 m, n = 44) and long-distance swimmers (LDSs, major event: 400-1,500 m, n = 50). Groups were subdivided into top-level and national-level athletes. We calculated the IGF genetic score (IGF-GS) of all the subjects on a 0-100 scale. Top-level SDRs' mean IGF-GS (30.8 ± 11.7) was significantly higher (p < 0.006) compared with national-level SDRs' (20.5 ± 11.3) and top-level SDSs' (19.9 ± 8.5). Subjects with IGF-GS >25 had an increased odds ratio (OR) of being elite-level SDRs (OR: 4.2; 95% confidence interval: 0.68-26.09; p < 0.001). In summary, a combined assessment of 6 single-nucleotide polymorphisms, all known to modulate circulation IGF1 levels, was associated with a higher genetic score among SDRs, emphasizing the importance of the IGF system to land speed sports events but not to swimming events. Whether the IGF-GS may be used for selection of elite-level sprinters in early stages of their athletic career needs to be further investigated.

Genetic Basis for the Dominance of Israeli Long-Distance Runners of Ethiopian Origin.

ABSTRACT: Ben-Zaken, S, Meckel, Y, Nemet, D, Kassem, E, and Eliakim, A. Genetic basis for the dominance of Israeli long-distance runners of Ethiopian origin. J Strength Cond Res 35(7): 1885-1896, 2021-Israeli long-distance runners of Ethiopian origin have a major influence on the track and field long-distance record table. The aim of this study was to determine whether genetic characteristics contribute to this long-distance dominance. We assessed polymorphisms in genes related to endurance (PPARD T/C), endurance trainability (ACSL A/G), speed (ACTN3 R/X), strength (AGT T/C), and the recovery from training (MTC1 A/T and IL6 G/C) among top Israeli long-distance runners of Ethiopian origin (n = 37), Israeli non-Ethiopian origin runners of Caucasian origin (n = 76), and Israeli nonathletic controls (n = 55). Israeli runners of Ethiopian origin had a greater frequency of the PPARD CC + PARGC1A Gly/Gly polymorphism, associated with improved endurance performance, compared with Israeli runners of non-Ethiopian origins (24 vs. 3%, respectively, p < 0.01); a lower frequency of the ACSL AA polymorphism, favoring endurance trainability (8 vs. 20%, respectively, p < 0.05); a greater frequency of the ACTN3 RR polymorphism, associated with sprint performance (35 vs. 20%, respectively, p < 0.05); a greater frequency of the MCT1 AA genotype, associated with improved lactate transport (65 vs. 45%, respectively, p < 0.05); and a lower frequency of IL-6 174C carriers, associated with reduced postexercise muscle damage (27 vs. 40%, respectively, p < 0.01). There was no difference in the frequency of AGT T/C gene polymorphism between the long-distance runners of Ethiopian and non-Ethiopian origin. Frequencies of PPARD CC + PARGC1A Gly/Gly, MCT1 AA, IL-6 174C, and AGT polymorphism were significantly favorable among Ethiopian, but not among non-Ethiopian, origin runners compared with controls. Taken together, results suggest that genetically, the dominance of Israeli long-distance runners of Ethiopian origin relates not only to endurance polymorphisms but also to polymorphisms associated with enhanced speed performance and better training recovery ability.

Sex Differences in Vitamin D Deficiency and Anthropometric Measurements in School-age Children from Rural Areas in Israel.

BACKGROUND: Vitamin D is essential for skeletal health. Because peak bone mass accrual occurs during childhood and adolescence, vitamin D insufficiency during this period of life could cause adverse health outcomes. OBJECTIVES: To explore the potential sex differences in anthropometric indicators and vitamin D status among primary school-age children. METHODS: A modified food-frequency intake questionnaire was completed by 116 pre-pubertal children (52 girls, 64 boys). Body measurements were recorded and blood was drawn to assess vitamin D status. All children were of Arab-Israeli origin and lived in villages or rural areas in the north-east area of Israel. RESULTS: Prevalence of obesity was higher among girls (34%) compared to boys (21.9%, P = 0.018). All the children were vitamin D insufficient, and 80% were deficient. Plasma vitamin D was significantly higher among boys (12.4 ng/ml) compared to girls (9.1 ng/ml, P < 0.01). A significant negative correlation was found between vitamin D status and weight percentile for girls (r = -0.43, P < 0.05) but not for boys. There was a trend toward a statistically significant inverse correlation between vitamin D status and body fat percent in the girls (r = -0.37, P = 0.07). Sex frameworks are important for the understanding of the determinants of health and the development of effective health promotion programs. CONCLUSIONS: Pre-pubertal girls in Arab villages should be provided with tailor-made nutrition and physical activity programs for promoting health.

The combined frequencies of the IL-6 G-174C and IGFBP3 A-202C polymorphisms among swimmers and runners.

Previous studies have demonstrated that compared to runners, swimmers carry a higher prevalence of the IL-6 -174C polymorphism and lower single nucleotide polymorphism frequencies of the IGF system. PURPOSE: The aim of the present study was to assess the combined frequency of the IL-6 -174G/C and IGFBP3 -202A/C polymorphisms among track and field athletes and swimmers. METHODS: Track and field athletes were divided into long-distance runners (major event 5000 m-marathon, n = 63) and power athletes (major event 100-200 m sprints and long jump, n = 67). Swimmers were divided into long-distance swimmers (major event: 400-1500 m, n = 50), and short-distance swimmers (major event: 50-100 m, n = 43). All participants had achieved results that ranked them among the top all-time Israeli athletes in their event, and competed at national and/or international level on a regular basis. RESULTS: Carrying both IL-6C and IGFBP3C mutations was significantly greater among long-distance swimmers (LDS - 44%) compared to long distance runners (LDR - 21%, p < .01), and among short distance swimmers (SDS - 49%) compared to sprinters and jumpers (S/J - 28%, p < .05). Among runners, the prevalence of those not carrying either of the two mutations was significantly higher among LDR (25%) compared to S/J (10%, p < .03). CONCLUSION: The prevalence of carrying both IL-6C and IGFBP3C mutations was significantly higher among the swimmers compared to runners. It is possible that carrying the IGFBP3C polymorphism is required to compensate for the potential genetically non-beneficial effects of a higher IL-6C genotype and an attenuated IGF system among the swimmers.

Correlates of Early-Stage Frailty-Sleep, Fitness, Oxidative Stress, and BMI.

Frailty reflects a decreased reserve in multiple systems resulting from cumulative decline. Frailty markers should be identified as early as possible to attenuate the loss of reserve. The aim of this study was to identify potentially modifiable correlates of frailty in relatively healthy older adults. Volunteers (n = 122) were recruited from local councils and, based on gender and age, were divided into one group of men aged 77.0 (±5.3), and two groups of women, aged 68.8 (±3.6) and aged 78.4 (±3.4). Frailty was assessed by a Frailty Index. The examined correlates were: physical activity, physical fitness (predicted peak VO2), sleep quality, oxidative stress (hydrogen peroxide-H2O2) and depression. Both groups of women had poor scores on physical fitness compared to women's norms. In order to examine the contribution of each of the potential correlates to explaining the variance of frailty, stepwise regressions were performed for each group separately. Based on the results, none of the suggested correlates significantly explained the variability of frailty in the men. In the younger-aged women, predicted peak VO2 and sleep quality explained 22.4% of the variability of frailty. In the older women, Body Mass Index (BMI), oxidative stress and sleep quality explained 34.9% of the variance. It is possible that increased aerobic fitness and interventions for improving sleep quality in older, seemingly healthy women will slow down the frailty process. Further research is needed to assess potential correlates of frailty, and to initiate suitable interventions to mitigate the signs of frailty at an early stage.

Genetic Variability Among Power Athletes: The Stronger vs. the Faster.

Ben-Zaken, S, Eliakim, A, Nemet, D, and Meckel, Y. Genetic variability among power athletes: the stronger vs. the faster. J Strength Cond Res XX(X): 000-000, 2019-Athletic events can be divided into "aerobic-type events" or "anaerobic-type events" based on energy usage. Power, speed, and strength are also used to specify sports subtypes. Weightlifters (WLs), sprinters, and jumpers feature high-intensity efforts lasting a few seconds. However, their performance requires different proportions of power, speed, and strength. The aim of the current study was to examine genetic differences between subtypes of anaerobic athletes in 3 genetic variants: ACTN3 R577X, which is associated with muscle contractions; AGT Met235Thr which is associated with muscle growth; and PPARD T/C, which is associated with aerobic capacity. Seventy-one sprinters and jumpers (S/J), 54 WLs, and 86 controls participated in the study. Genomic DNA was extracted from peripheral blood using a standard protocol. Genotypes were determined using a TaqMan allelic discrimination assay. The ACTN3 RR genotype frequency was significantly higher among S/J (39.4%) compared with WLs (22.2%) and controls (18.6%). The AGT Thr-Thr genotype frequency was significantly higher among WLs (25.9%) compared with S/J (4.2%) and controls (12.8%). PPARD T294C genotype frequencies did not differ between groups. The results suggest that there may be a specific genetic makeup enabling an athlete to excel in speed-oriented events (sprints), rather than in strength-oriented events (weightlifting).

High prevalence of the IGF2 rs680 GG polymorphism among top-level sprinters and jumpers.

Previous studies have shown that the IGF1 polymorphism is associated with greater muscle mass and improved power athletic ability, but very little is known about the IGF2 polymorphism and athletic performance. PURPOSE: The aim of the present study was to assess the frequency distribution of the IGF2 rs680 polymorphism among Israeli athletes. METHODS: 185 short- (n=72) and long-distance (n=113) runners, 94 short- (n=44) and long-distance (n=50) swimmers, 54 weight lifters and 111 controls participated in the study. Genomic DNA was extracted from peripheral EDTA treated anti-coagulated blood using a standard protocol. Genotyping of the IGF2 A/G polymorphism (rs680) was performed using allelic discrimination assay. RESULTS: The frequency of IGF2 (rs680) G allele carriers was significantly greater among top compared to national-level track and field sprinters and jumpers (p<0.05). The IGF2 (rs680) GG genotype frequency was significantly greater among track and field sprinters and jumpers compared to weight lifters p<0.02), and among top-level sprinters and jumpers compared to top-level weight lifters p<0.01). There were no statistically significant differences in the IGF2 (rs680) GG genotype frequency among endurance athletes and between the swimmers and the other sports disciplines and the controls. CONCLUSIONS: While a single polymorphism cannot determine athletic success or failure, the findings of the present study suggest a potential importance of the IGF2 polymorphism, mainly regarding speed sport performance.

Increased Prevalence of the IL-6-174C Genetic Polymorphism in Long Distance Swimmers.

The IL-6 -174G/C single nucleotide polymorphism (SNP) functionally affects IL-6 activity, with the G-allele associated with increased IL-6 levels. The C-allele was found to be associated with exercise-induced skeletal muscle damage. The aim of the present study was to examine the association between the IL-6 -174G/C polymorphism and athletic performance among elite swimmers and runners. The study sample included 180 track and field athletes and 80 swimmers. Track and field athletes were assigned to three sub-groups: long-distance runners, middle-distance runners and short-distance runners. Swimmers were assigned to two subgroups: long-distance swimmers and short-distance swimmers. The control group consisted of 123 non-athletic healthy individuals. Genomic DNA was extracted from peripheral blood following a standard protocol. Genotyping was performed using polymerase chain reaction (PCR). The CC genotype and C-allele frequency were significantly higher in the long-distance swimmers (18 and 43%, respectively) compared to the long-distance runners (3 and 14%, respectively, p < 0.001); middle-distance runners (4 and 22%, respectively, p < 0.001); and controls (5 and 19%, respectively, p < 0.001). In addition, the CC genotype and C-allele frequency were significantly higher (p < 0.001) in long-distance swimmers compared to short-distance swimmers (18 versus 5% and 43 versus 29% for the CC genotype and C-allele frequency, respectively). The higher frequency of the C-allele and CC genotype among long-distance swimmers suggests that the rarity of exercise-associated rhabdomyolysis among swimmers is probably related to other sports-specific or water-related protective mechanisms. It is possible that swimming selection in talented endurance athletes who are C-allele carriers represents an example of genetically-dependent sports selection.

The combined frequency of IGF and myostatin polymorphism among track & field athletes and swimmers.

OBJECTIVE: The IGF C-1245T (rs35767) and the myostatin (MSTN) Lys(K)-153Arg(R) genetic polymorphism may influence skeletal muscle phenotypes and athletic performance. Carrying the minor IGF T allele and the myostatin rare R allele was associated with higher circulating IGF-I levels, greater muscle mass and improved performance. The aim of the present study was to assess the combined frequency of the IGF 1245T (rs35767) and MSTN 153Arg(R) polymorphism among Israeli track and field athletes (n=111) and swimmers (n=80). DESIGN: Track & field athletes were divided to long distance runners (major event 5000m-marathon, n=63) and power athletes (major event 100-200m sprints and long jump, n=48). Swimmers were divided into long-distance swimmers (major event: 400-1500m, n=38), and short-distance swimmers (major event: 50-100m, n=42). RESULTS: Carrying both mutations was significantly higher (p<0.05) among long distance runners (LDR, 17%) compared to short distance runners (SDR, 10%), long distance swimmers (LDS, 8%), short distance swimmers (SDS, 2%) and controls (n=111, 7%). Carrying both mutations was significantly higher (p<0.05) among LDS compared to SDS (8% versus 2%, p<0.05). Among LDR and LDS carriers of both mutations, 40% and 25% were of elite level, respectively. Despite the fact that carrying both mutations among SDR and SDS was not greater than controls, all SDR and SDS carriers were elite athletes. CONCLUSION: Our finding suggests that carrying both IGF 1245T and MSTN 153Arg(R) polymorphisms may contribute for long distance running success but not necessarily to elite performance. In contrast, although the frequency was not higher than the general population, all carriers of both mutations among short distance runners and swimmers were of elite competitive caliber. Whether evaluation of the IGF 1245T and MSTN 153R polymorphism can be used for sports selection in young athletes needs to be further studied.

Polymorphism of the IGF-I System and Sports Performance.

The potential use genetic polymorphism, and in particularly polymorphism of hormone genes, as tool to predict athletic performance is currently very challenging. Recent studies suggest that single nucleotide polymorphisms in IGF-I and myostatin may be beneficial for endurance and short distance running, and may even be associated with elite performance. Polymorphism in IGF-I receptor may differentiate between the two edges of the endurance-power athletic performance running spectrum suggesting beneficial effects for endurance and prevent from success in power events. In contrast, and despite similar metabolic demands, the myostatin-IGF-I-IGF-IR system seems not to play an important role in swimming excellence. This suggests that combining different sport disciplines for sports genetic research purposes should be done with extreme caution. Finally, since any phenotype reflects a complex relationship between genes, environment, epigenetic factors, and the interactions between them, consulting the young athlete regarding future success cannot be based solely on genetic polymorphism.

ACTN3 Polymorphism: Comparison Between Elite Swimmers and Runners.

BACKGROUND: The human ACTN3 gene encodes α-actinin-3, an actin-binding protein with a pivotal role in muscle structure and metabolism. A common genetic single nucleotide polymorphism (SNP) at codon 577 of the ACTN3 results in the replacement of an arginine (R) with a stop codon (X). The R allele is a normal functional version of the gene, whereas the X allele contains a sequence change that completely stops production of functional α-actinin-3 protein. The ACTN3 R577X polymorphism was found to be associated with power athletic performance especially among track and field athletes. The aim of the current study was to compare allelic and genotype frequencies of the ACTN3 R577X polymorphism among runners and swimmers specializing in different distances, and >non-athletic controls. METHODS: One hundred and thirty-seven runners, 91 swimmers and 217 controls, participated in the study. Runners were assigned to two subgroups according to their event specialty-long-distance runners (LDR) and short-distance runners (SDR). Swimmers were also assigned to two subgroups according to their main swimming event-long-distance swimmers (LDS) and short-distance swimmers (SDS). Genomic DNA was extracted from peripheral EDTA-treated anti-coagulated blood using a standard protocol. Genotypes were determined using the Taqman allelic discrimination assay. RESULTS: Runners' genotype and allele differed significantly between LDR, SDR, and controls, with the lowest prevalence of RR genotype and R allele among LDR. XX genotype and X allele prevalence was significantly higher among LDR compared to the other groups (p < 0.01 for all). On the other hand, swimmers' genotype and allele frequencies did not differ significantly between subgroups (LDS and SDS). Yet, LDS had significantly higher RR genotype and R allele frequencies compared to LDR. CONCLUSIONS: The findings suggest that while ACTN3 R577X polymorphism is a genetic polymorphism that may distinguish between SDR and LDR, it cannot differentiate significantly between SDS and LDS. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01319032. KEY POINTS: ACTN3 R577X polymorphism is largely associated with running events specialization, with high prevalence of RR genotype and R allele frequency among short-distance runners compare to long-distance runners.Unlike in running, ACTN3 R577X polymorphism is not associated with swimming specialization.The inability of the ACTN3 R577X polymorphism to distinguish between swimmers specializing in different events, presumably since other factors such as body physique, technique, tactics, etc., are more likely to determine such a distinction.

Rhabdomyolysis After Out-of-Water Exercise in an Elite Adolescent Water Polo Player Carrying the IL-6 174C Allele Single-Nucleotide Polymorphism.

We present an adolescent elite water polo player who despite a genetic predisposition to develop exercise-induced severe muscle damage due to carrying the IL-6 174C allele single-nucleotide polymorphism, developed acute rhabdomyolysis only after a vigorous out-of-water training, suggesting that water polo training may be more suitable for genetically predisposed athletes.

Frequency of the MSTN Lys(K)-153Arg(R) polymorphism among track & field athletes and swimmers.

UNLABELLED: The myostatin (MSTN) Lys(K)-153Arg(R) polymorphism may influence skeletal muscle phenotypes. Carrying the rare R allele was associated with greater muscle mass. PURPOSE: The aim of the present study was to assess the frequency of the MSTN Lys(K)-153Arg(R) polymorphism among Israeli track and field athletes (n=185) and swimmers (n=80). METHODS: Track and field athletes were divided into long distance runners (major event 5000 m-marathon, n=113) and power athletes (major event 100200 m sprints and long jump, n=72). Swimmers were divided into long-distance swimmers (major event: 800-1500 m, n=38), and short-distance swimmers (major event: 50-100 m, n=42). The control group included 118 non-athletes healthy participants. RESULTS: Twenty-seven track and field athletes (14.6%) and 7 swimmers (8.8%) were carriers of the rare MSTN R allele, and only two carried the 153RR genotype (0.8%). MSTN 153R allele frequency was significantly higher in top-compared to national-level among long-distance runners (26% versus 8%, p<0.05), short distance runners (16% versus 9%, p<0.05), and all runners combined (20% versus 8%, p<0.05), but not in top- compared to national-level swimmers. The frequency of arginine carriers was significantly greater among long compared to short-distance swimmers (16% versus 2%, p<0.03). CONCLUSION: In contrast to elite endurance and power track and field athletes, the MSTN 153RR genotype was not found in short distance-swimmers, and among the long distance-swimmers it was not associated with top level swimming performance. Whether evaluation of the MSTN K153R polymorphism can be used for sports selection in young athletes needs to be further studied.