Do PON1-Q192R and PON1-L55M polymorphisms modify the effects of hypoxic training on paraoxonase and arylesterase activity?

Background:Low levels of antioxidant paraoxonase 1(PON 1)enzyme activity,PON1-Q192R polymorphism(a glutamine(Q)to arginine(R)substitution at position 192),PON1-L55M polymorphism(a leucine(L)to methionine(M)substitution at position 55),and oxidized low-density lipoprotein(oxLDL)are risk factors for coronary heart disease.Aerobic exercise improves PON1 activity,but the effects of hypoxic exercise are yet unclear.The aim of this study was to determine the effects of hypoxic underwater rugby training on PON1 activity and oxLDL levels and the role of the mentioned polymorphisms.Methods:Serum PON1 and arylesterase activities(ARE),PON1,PON3,and oxLDL protein levels(by using the enzyme-linked immunosorbent assays)were determined in an athletic group(42 trained male underwater rugby players;age=21.7±4.2 years,mean±SD)and a control group(43 sedentary men;age=23.9±3.2 years).The polymorphisms were determined from genomic DNA samples.Results:PON1 activity(25.1%,p=0.052),PON3(p<0.001),and oxLDL(p<0.001)of the athletic group,including most genotype groups,were higher than those of the control group.In comparison to the controls,PON1 activity levels(p=0.005)of the PON1-Q192R homozygote QQ genotype group and PON1 activity levels(30%,p=0.116)of the PON1-L55M homozygote LL genotype group were higher,whereas ARE activity values of athletic R allele carrier(Rc=QR+RR)(p=0.005)and LL group(p=0.002)were lower than the control genotype groups related to their polymorphisms.Conclusion:Hypoxic training can cause(1)significant oxidative stress,including oxLDL,and an antioxidant response(increase in PON1 activity and PON3),(2)differences in the activity of PON1 and ARE,which are modified by PON1-Q192R and PON1-L55M polymorphisms,respectively,and(3)improvements in PON1 activity of QQ and LL groups.However,hypoxic training can cause a disadvantage of LL and Rc groups for ARE.

Practical Application of Altitude/Hypoxic Training for Olympic Medal Performance:The Team USA Experience

Although scientific conclusions remain equivocal,there is evidence-based research,as well as anecdotal support,suggesting that altitude training can enhance performance among Olympic level athletes,particularly in endurance sport.This appears to be due primarily to hypoxia-induced increases in total hemoglobin mass and subsequent improvements in maximal oxygen uptake and other factors contributing to aerobic performance.Although less clear,it is possible that non-hematological adaptations may contribute secondarily to improvements in post-altitude performance.These physiological effects are most likely realized when the altitude exposure is of sufficient“hypoxic dose”to provide the necessary stimuli for performance-affecting changes to occur via hypoxia-inducible factor 1α(HIF-1α)and hypoxia-inducible factor 2α(HIF-2α)pathways and their downstream molecular signaling.Team USA has made a strong commitment over the past 20 years to utilizing altitude training for the enhancement of performance in elite athletes in preparation for the Olympic Games and World Championships.Team USA’s strongest medal-producing Olympic sports-USA Swimming and USA Track and Field-embraced altitude training several years ago,and they continue to be leaders within Team USA in the practical and successful application of altitude training.Whereas USA Swimming utilizes traditional“live high and train high”(LH+TH)altitude training,USA Track and Field tends more toward the use of the altitude training strategy whereby athletes live high(and potentially sleep higher,either naturally or via simulated altitude),while training high during moderate-intensity(<lactate threshold 2)training sessions,and train low during high-intensity(>lactate threshold 2)training sessions(LH+TH_([<LT])+TL_([>LT])).Although USA Swim-ming and USA Track and Field have taken different approaches to altitude training,they have been equally successful at the Olympic Games and World Championships,both teams being ranked first in the world based on medals earned in these major international competitions.In addition to USA Swimming and USA Track and Field,several other Team USA sports have had consistently competitive performance results in conjunction with regular and systematic altitude training blocks.The purpose of this paper was to describe select altitude training strategies used by Team USA athletes,and the impact of those strategies on podium performance at major international competitions,specifically the Olympic Games and World Championships.

Effects of hypoxic exercise training on microRNA expression and lipid metabolism in obese rat livers

To investigate the effects of hypoxic exercise training on microRNA （miRNA） expression and the role of miRNA expression in regulating lipid metabolism, 20 dietary-induced obese SD rats were divided into a normoxic sedentary group （N, n=10） and a hypoxic exercise training group （H, n=10）. After four weeks, measurements were taken of body weight, body length, fat mass, serum lipid concentration, miRNAs differentially expressed in rat liver, and gene and protein expression levels of perexisome proliferator activated receptor a （PPARα）, fatty acid synthetase （FAS）, and carnitine palmitoyl transferase 1A （CPTIA） in rat liver. Body weight, Lee＇s index, fat mass, fat/weight ratio, and serum levels of total cholesterol （TC） and high density lipoprotein cholesterol （HDL-C） were all significantly lower in the H group than in the N group （P〈0.01）. Six miRNAs expressed significantly differently in the liver （P〈0.05）. Specifically, expression levels of miR-378b were significantly lower in the H group than in the N group （P〈0.05）. Compared with the normoxic sedentary group, hypoxic exercise training resulted in a lower ratio of FAS mRNA to CPTIA mRNA （P〈0.05）, as well as lower CPT1A protein levels （P〈0.01）, while a higher ratio of FAS to CPT1A protein levels （P〈0.01） was observed. In conclusion, hypoxic training may elevate the resistance of high fat diet induced obesity in rats by reducing the expression of miR-378b, and decrease the fatty acid mitochondrial oxidation in obese rat livers by decreasing the protein expression of CPTIA and increasing the protein expression ratio of FAS/CPTIA.