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June 3 2:15 PM - 2:30 PM Mitochondrial DNA Polymorphisms Associated with Elite Kenyan Endurance Runners Noriyuki Fuku1, Michael Seiler2, Robert A. Scott3, Liyang Diao2, Gyan Bhanot2, Masashi Tanaka1, Yannis P. Pitsiladis, FACSM4. 1Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan. 2Rutgers University, Piscataway, NJ. 3Cambridge University, Cambridge, United Kingdom. 4University of Glasgow, Glasgow, United Kingdom. Email:
[email protected] (No relationships reported)
We recently reported an association between mitochondrial haplogroups (i.e., a set of mitochondrial DNA (mtDNA) polymorphisms) and elite Kenyan athlete status (Scott et al, MSSE, 2009). PURPOSE: To identify by direct mtDNA sequencing the polymorphisms that may significantly associate with elite Kenyan endurance athlete status. METHOD: Complete mtDNA sequences were analyzed by direct sequencing in 74 elite Kenyan endurance runners (including world and Olympic champions and world record holders) and compared to 893 African controls (http://www.mitomap.org/MITOMAP). Frequency differences in mtDNA polymorphisms between athletes and controls were examined by permutation tests. RESULTS: 15 polymorphisms were significantly different between athletes and controls: 4 polymorphisms in the L0 clade (3808A>G, 5581A>G, 15317A>G, and 16184C>T) and 11 polymorphisms in the L3 clade (489T>C, 813A>G, 6446G>A, 6671T>C, 10400C>T, 12403C>T, 12950A>C, 14110T>C,14783T>C, 15043G>A, and 16249T>C). Among these polymorphisms, two in haplogroup L0 and three in haplogroup L3 (12403C>T, 12950A>C, and 14110T>C) were nonsynonymous substitutions. In the L0 clade, an enrichment in endurance runners was found for Thr168Ala replacement in NADH dehydrogenase subunit 1 (ND1) gene and Ala191Thr replacement in Cytochrome b gene. In the L3 clade, an enrichment in endurance runners was found for Leu23Phe, Asn205Thr, and Phe592Leu replacements in the ND5 gene. These polymorphisms with amino acid replacements can potentially influence mitochondrial oxidative phosphorylation. One SNP (813A>G) in the L3 clade was located in mitochondrial 12S ribosomal RNA gene and may function by changing the rRNA secondary structure. CONCLUSIONS: Two polymorphisms related to haplogroup L0 and four polymorphisms related to haplogroup L3 with the potential to influence mitochondrial function were found to associate with elite Kenyan endurance status.
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Free Communication/Slide - Normobaric Hypoxia JUNE 3, 2011 1:00 PM - 2:45 PM ROOM: 506
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Chair: Robert R. Kraemer, FACSM. Southeastern Louisiana University, Hammond, LA. (No relationships reported)
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June 3 1:00 PM - 1:15 PM No Evidence For The “Normobaric Oxygen Paradox” Tadej Debevec1, Michail E. Keramidas1, Barbara Norman2, Thomas Gustafsson2, Ola Eiken3, Igor B. Mekjavic1. 1Jozef Stefan Institute, Ljubljana, Slovenia. 2Karolinska Institute, Stockholm, Sweden. 3Royal Institute of Technology, Stockholm, Sweden. Email:
[email protected] (No relationships reported)
PURPOSE: Renal tissue hypoxia is an established trigger of de novo erythropoietin (EPO) production. It has recently been suggested that EPO synthesis may be stimulated also by relative hypoxia, induced by an acute exposure to hyperoxia followed by a return to normoxia. This phenomenon has been termed the “normobaric oxygen paradox”. The purpose of this study was to evaluate whether such relative hypoxia, induced by acute and successive exposures to hyperoxia and hypoxia can stimulate EPO synthesis. METHODS: [EPO] was measured in ten healthy males before, in the middle, and after a 2 hr hyperoxic/hypoxic (HH) protocol comprising breathing oxygen (FiO2=1.0) for 60 minutes, followed by breathing a hypoxic mixture (FiO2=0.15 ) for 60 minutes. Values were compared with those obtained during the trial in which eight matched subjects breathed a normoxic air mixture for 2 hrs (Normoxic trial). Thereafter, blood samples were taken 3, 5, 8, 24, 32 and 48 hours after the cessation of HH and Normoxic exposures. RESULTS: There were no significant differences in absolute [EPO] between the HH and Normoxic trials. Significant within group differences in [EPO] were observed; [EPO] was significantly higher at 8 (+ 60%) and 32 h (+ 49%) in the Normoxic, and at 32 h (+ 49%) in the HH trial, compared to values before the trials. In addition, the relative ∆[EPO] values were significantly lower in the HH trials compared to the Normoxic 5 and 8 hours following the exposure. CONCLUSION: Successive and acute periods of breathing hyperoxic and hypoxic gas mixtures did not augment [EPO] synthesis, which in both the HH and Normoxia seems to follow a circadian rhythm. The present results do not support the theory of a “normobaric oxygen paradox”. ACKNOWLEDGEMENTS: Supported, in part, by the Slovene Research Agency (Slovenia) and b-Cat (The Netherlands).
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June 3 1:15 PM - 1:30 PM Effects of Normobaric Hypoxia Training on Physical Fitness and Metabolic Risk Markers in Sedentary Men Takuma Morishima, Kazushige Goto. Ritsumeikan University, Kusatsu, Japan. (Sponsor: Robert Kraemer, FACSM) Email:
[email protected] (No relationships reported)
PURPOSE: To investigate the effects of normobaric hypoxia training on physical fitness and metabolic risk markers in sedentary men. METHODS: Twenty healthy men were divided to two groups; normobaric hypoxia training group (HYPO; n = 9, 30 ± 2 yrs, 74 ± 4 kg, FiO2 = 15 %) and normoxia training group (NOR; n = 11, 32 ± 3 yrs, 74 ± 4 kg, FiO2 = 21 %). Each exercise was conducted with a cycle ergometer at 55% of maximal oxygen uptake (VO2max) for each environment 3 days per week over a 4-week period. Before and after the training period, whole body fat mass (measured by DXA), VO2max, as well as fasting and postprandial (for 180 min following a 600 kcal test meal) glucose and insulin concentrations were determined. RESULTS: Workload during the exercise was significantly lower in the HYPO group (92 .(0.05 >P ;W 7 ± 111)compared with the NOR group (;W 4 ± whole body fat ,dweek training perio-4After a .(0.06 =P ,3 ± 131 .vs 4 ± 139)HYPO group showed higher heart rate than NOR group whereas no c ,(0.08 =P )mass tended to decrease in the HYPO group hange was observed in NOR group. Both groups showed significant increases in VO2max following training period (P < 0.05), with no difference between the groups. Although time to exhaustion (TTE) during VO2max test significantly increased
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