n-3 Polyunsaturated Fatty Acids Are Associated with Stable Nitric Oxide Metabolites in Highly Trained Athletes.

BACKGROUND: The aim of this study was to investigate the relationships between levels of n-3 essential polyunsaturated fatty acids (n-3 PUFAs) and stable nitric oxide (NO) metabolites in the plasma of athletes. METHODS: Highly trained cross-country skiers (males, n = 39) were examined. The fatty acid profile of the total plasma lipids was determined by gas chromatography. The plasma NO level was studied by a colorimetric method via reaction with Griess reagent. RESULTS: A widespread deficiency of essential n-3 PUFAs in the plasma of athletes (more than 80% of the subjects) was demonstrated in association with an imbalance in the levels of nitrates (NO3) and nitrites (NO2). A lower value of n-3 linolenic acid in the plasma (0.21 mol/%) was associated with a NO3 level below the normal range (n-3 C18:3 and NO3 Rs = 0.461; p = 0.003). Higher levels of n-3 eicosapentaenoic acid (0.8 mol/%) were associated with a concentration of NO2 above the normal value (n-3 C20:5 and NO2 Rs = 0.449; p = 0.004). CONCLUSION: For the first time, the participation of essential n-3 PUFAs in the nitrite-nitrate pathway of NO synthesis in highly trained skiers was demonstrated.

The Prevalence of Low Energy Availability in Cross-Country Skiers during the Annual Cycle.

BACKGROUND AND OBJECTIVES: A sustained mismatch between energy intake (EI) and exercise energy expenditure (EEE) can lead to Low Energy Availability (LEA), as well as health and performance impairments characteristic of Relative Energy Deficiency in Sport (RED-S). Research in females has identified specific LEA cut-points for the risks of developing physiological and performance disturbances. Cut-points in males have yet to be evaluated; therefore, this study examined the prevalence of LEA in highly trained male cross-country skiers. The key purpose of this study was to analyze EI, resting energy expenditure (REE), EEE, and energy availability (EA) in highly trained cross-country skiers during the preparation and competition periods. The secondary objective of our study was to evaluate the relative contribution of fats and carbohydrates to EI, REE, and EEE. MATERIALS AND METHODS: EI was determined by an estimated 24 h diet recall method, REE was assessed by indirect calorimetry, and EEE was estimated from heart rate in 27 cross-country skiers. RESULTS: EI amounted to 4050 ± 797 kcal/day on a typical training day (TD) and 5986 ± 924 kcal/day (p < 0.001) on a typical competition day (CD). REE on TDs (2111 ± 294 kcal/day or 30 ± 6 kcal/day/kg) was higher (p < 0.05) than on CDs (1891 ± 504 kcal/day or 27 ± 7 kcal/day/kg). The EA in the athletes was <15 kcal∙kg FFM-1·d-1 on TDs and <65 kcal∙kg FFM-1·d-1 on CDs. EI was not optimal, as indicated by low EA throughout TDs (June). This could be associated with insufficient EI along with a high amount of EEE (3690.7 ± 485.2 kcal/day). During the transition from TD to CD, an increase in the contribution of fats to EI and EEE was observed in cross-country skiers. CONCLUSION: The conception of LEA and REDs and their potential implication for performance is underestimated among coaches and athletes. The importance of appropriate dietary strategies is essential to ensure that enough calories are consumed to support efficient training.

Cardiac repolarisation indices are associated with oxygen consumption during maximal exercise test in highly-trained cross-country skiers.

The objective of this study was to test the vectorelectrocardiographic T-wave characteristics for their associations with oxygen consumption (VO2) and physical performance during a maximal cardiopulmonary exercise test (CPET) in highly trained cross-country skiers. Male highly trained cross-country skiers (n = 30) performed the maximal CPET on the bicycle ergospirometric "Oxycon Pro" system with simultaneous oxygen consumption (VO2) and electrocardiogram recording. The measurements were done at rest; the stage preceding anaerobic threshold (preAnT); peak load; and recovery. The anaerobic threshold was estimated by respiratory exchange ratio. Physical performance was estimated by maximal oxygen consumption (VO2max/kg). VECG characteristics were calculated using Kors transformation procedure. During the test, the magnitudes of T-vector, Tx and Ty components decreased until preAnT, then stayed relatively stable until peak load, and reversed during recovery. In univariate linear regression analysis, T-vector amplitude and Tx, Ty and Tz magnitudes were associated with VO2/kg during the test (p < 0.010). The baseline T-vector characteristics were not associated with physical performance. At the preAnT stage, Tx and T-vector amplitude were associated with VO2max/kg (RC 12.70, 95% CI 0.68-24.73, p = 0.039 and RC 10.64, 95% CI 1.62-19.67, p = 0.023, respectively).

Fatty liver index (FLI): more than a marker of hepatic steatosis

Fatty liver index (FLI) was developed as a simple and accurate marker of hepatic steatosis. FLI is derived from an algorithm based on body mass index, waist circumference, and levels of triglycerides and gamma-glutamyltransferase, and it is widely used in clinical and epidemiological studies as a screening tool for discriminating between healthy and nonalcoholic fatty liver disease (NAFLD) subjects. However, a systematic review of the literature regarding FLI revealed that this index has more extensive relationships with biochemical and physiological parameters. FLI is associated with key parameters of lipid, protein and carbohydrate metabolism, hormones, vitamins and markers of inflammation, or oxidative stress. FLI can be a predictor or risk factor for a number of metabolic and nonmetabolic diseases and mortality. FLI is also used as an indicator for determining the effects of health-related prevention interventions, medications, and toxic substances on humans. Although in most cases, the exact mechanisms underlying these associations have not been fully elucidated, they are most often assumed to be mediated by insulin resistance, inflammation, and oxidative stress. Thus, FLI may be a promising marker of metabolic health due to its multiple associations with parameters of physiological and pathological processes. In this context, the present review summarizes the data from currently available literature on the associations between FLI and biochemical variables and physiological functions. We believe that this review will be of interest to researchers working in this area and can provide new perspectives and directions for future studies on FLI. (AU)

Fatty liver index (FLI): more than a marker of hepatic steatosis

Fatty liver index (FLI) was developed as a simple and accurate marker of hepatic steatosis. FLI is derived from an algorithm based on body mass index, waist circumference, and levels of triglycerides and gamma-glutamyltransferase, and it is widely used in clinical and epidemiological studies as a screening tool for discriminating between healthy and nonalcoholic fatty liver disease (NAFLD) subjects. However, a systematic review of the literature regarding FLI revealed that this index has more extensive relationships with biochemical and physiological parameters. FLI is associated with key parameters of lipid, protein and carbohydrate metabolism, hormones, vitamins and markers of inflammation, or oxidative stress. FLI can be a predictor or risk factor for a number of metabolic and nonmetabolic diseases and mortality. FLI is also used as an indicator for determining the effects of health-related prevention interventions, medications, and toxic substances on humans. Although in most cases, the exact mechanisms underlying these associations have not been fully elucidated, they are most often assumed to be mediated by insulin resistance, inflammation, and oxidative stress. Thus, FLI may be a promising marker of metabolic health due to its multiple associations with parameters of physiological and pathological processes. In this context, the present review summarizes the data from currently available literature on the associations between FLI and biochemical variables and physiological functions. We believe that this review will be of interest to researchers working in this area and can provide new perspectives and directions for future studies on FLI. (AU)

Fatty liver index (FLI): more than a marker of hepatic steatosis.

Fatty liver index (FLI) was developed as a simple and accurate marker of hepatic steatosis. FLI is derived from an algorithm based on body mass index, waist circumference, and levels of triglycerides and gamma-glutamyltransferase, and it is widely used in clinical and epidemiological studies as a screening tool for discriminating between healthy and nonalcoholic fatty liver disease (NAFLD) subjects. However, a systematic review of the literature regarding FLI revealed that this index has more extensive relationships with biochemical and physiological parameters. FLI is associated with key parameters of lipid, protein and carbohydrate metabolism, hormones, vitamins and markers of inflammation, or oxidative stress. FLI can be a predictor or risk factor for a number of metabolic and nonmetabolic diseases and mortality. FLI is also used as an indicator for determining the effects of health-related prevention interventions, medications, and toxic substances on humans. Although in most cases, the exact mechanisms underlying these associations have not been fully elucidated, they are most often assumed to be mediated by insulin resistance, inflammation, and oxidative stress. Thus, FLI may be a promising marker of metabolic health due to its multiple associations with parameters of physiological and pathological processes. In this context, the present review summarizes the data from currently available literature on the associations between FLI and biochemical variables and physiological functions. We believe that this review will be of interest to researchers working in this area and can provide new perspectives and directions for future studies on FLI.

Sex differences in the association between obesity and hypertension.

BACKGROUND: Hypertension and obesity often coexist. There are sex differences in the mechanisms of obesity-related hypertension but the reasons for these differences are still not fully understood. OBJECTIVE: The aim of this study was to investigate sex differences in the development of hypertension associated with obesity. METHODS: A total of 866 men and 1022 women were selected for the study. Anthropometric measurements, including arterial pressure measurements, were performed. The plasma lipid levels were measured using an enzymatic method with commercially available kits. RESULTS: In both overweight and obesity, hypertensive women had more atherogenic lipid profiles and higher values of lipid accumulation product (LAP) than normotensive women. In overweight and obese men, no significant differences in lipid levels or LAP were noted between the normotensive and hypertensive groups. CONCLUSION: The pathogenesis of obesity-related hypertension in women differs from that in men and tends to be associated with metabolic disorders.

Association of serum 25-hydroxyvitamin D with metabolic disturbances in adolescents.

OBJECTIVES: Data concerning the association of vitamin D with metabolic disturbances in adolescents are contradictory. The aim of this study was to identify metabolic abnormalities in adolescents with 25-hydroxyvitamin D (25[OH]D) deficiency and to determine informative indices for the early detection of these metabolic disturbances. METHODS: A cross-sectional observational study including 90 adolescents aged 13-15 years was carried out during the winter. Anthropometric measures were collected. Fasting blood samples were assessed for the following parameters: serum 25(OH)D, lipids, and glucose. RESULTS: The majority of the study adolescents had low 25(OH)D concentration. The prevalence of 25(OH)D deficiency (<12 ng/ml) and insufficiency (12-20 ng/ml) in adolescents was 34.4% and 55.6%, respectively. Among the metabolic disturbance, hypo-high-density lipoprotein cholesterolemia prevailed in the adolescents, while hypercholesterolemia, hypertriglyceridemia, and hyperglycemia were rare. 25(OH)D status showed an association with the metabolic score for insulin resistance (METS-IR, r = -0.40; p < .001), high-density lipoprotein cholesterol level (r = 0.31; p = .003), atherogenic index of plasma (r = -0.30; p = .004) and body mass index (r = -0.23, p = .032). There were no significant correlations between 25(OH)D level and other lipid or glucose levels. The degree of hypovitaminosis D affects METS-IR values. CONCLUSIONS: 25(OH)D deficiency in the studied adolescents had not yet manifested serious metabolic diseases. Of all the analyzed parameters, METS-IR was most strongly associated with 25(OH)D level and can be considered a useful marker of early metabolic disturbances in adolescents with 25(OH)D deficiency.

Age-adjusted cut-off values of lipid accumulation product (LAP) for predicting hypertension.

Among the many factors considered relevant to hypertension, obesity and metabolic disturbances play an important role in the development of this pathology. Therefore, lipid accumulation product (LAP), an index of visceral adiposity, is a simple and effective indicator of hypertension risk. To date, the reference and cut-off values for LAP have not been defined. The aim of the study was to determine the age-adjusted optimal cut-off values of LAP for the prediction of hypertension risk. This cross-sectional case-control study comprised 1960 subjects ranging from 20 to 64 years of age. The participants underwent anthropometric tests, blood pressure measurements, questionnaire surveys and laboratory examinations. The cut-off values of LAP were determined using receiver operating characteristic (ROC) curve analysis. According to our study results, LAP values in healthy subjects increased with age, whereas there was no effect of age on LAP values in patients with hypertension. These two findings determine the presence of age-adjusted cut-off values of LAP for diagnosing hypertension. Increasing age is associated with an increase in the cut-off values of LAP to detect hypertension. In conclusion, hypertension risk should be estimated using the age-adjusted cut-off values of LAP; otherwise, the risk of hypertension might be overestimated or underestimated.

Features of Metabolic Support of Physical Performance in Highly Trained Cross-Country Skiers of Different Qualifications during Physical Activity at Maximum Load.

The purpose of our study was to identify the features of metabolic regulation in highly trained cross-country skiers of different qualifications at different stages of the maximum load test. We examined 124 highly trained cross-country skiers (male, ages 17-24). The group consisted of two subgroups based on their competition performance: 61 nonelite athletes (Group I) and 63 elite athletes (group II), who were current members of the national team of the Komi Republic and Russia. The bicycle ergometer test was performed by using the OxyconPro system (Erich Jaeger, Hoechberg, Germany). All the examined athletes performed the exercise test on a cycle ergometer "until exhaustion". The results of our research indicate that the studied groups of athletes with high, but different levels of sports qualifications are a convenient model for studying the molecular mechanisms of adaptation to physical loads of maximum intensity. Athletes of higher qualifications reveal additional adaptive mechanisms of metabolic regulation, which is manifested in the independence of serum lactate indicators under conditions of submaximal and maximum power from maximal oxygen uptake, and they have an NO-dependent mechanism for regulating lactate levels during aerobic exercise, including work at the anaerobic threshold.

Nitric Oxide Production in Professional Skiers During Physical Activity at Maximum Load.

The purpose of this study is to assess the production of nitric oxide in professional cross-country skiers with normotensive and hypertensive responses to physical activity at maximum load. The observation group included professional cross-country skiers (22.2 ± 7.1 years, = 107) who were current members of the national team of the Komi Republic. All the examined athletes performed the exercise test on a cycle ergometer "until exhaustion." The following parameters were determined for each participant while they were sitting at rest, while at their anaerobic threshold level, during peak load, and during the recovery period (5th min): systolic blood pressure, diastolic blood pressure, heart rate, and the level of stable nitric oxide metabolites (nitrites, nitrates) in capillary blood samples. According to the blood pressure results, the cross-country skiers were divided into two groups. Group I included athletes with a normotensive response to stress. Group II was composed of individuals with a hypertensive response to stress. During the performance of the test "until exhaustion," a significant (p < 0.05) increase in the amount of stable metabolites of nitric oxide was observed in the group of athletes with a normotensive response to the load compared with the group with a hypertensive response to the load. In athletes with a normotensive reaction to the load during exercise at maximum load and in the early recovery period, nitrate was prioritized in the regulation of vascular tone. The exercise test on a cycle ergometer "until exhaustion," combined with the assessment of the levels of stable nitric oxide metabolites in plasma, can be considered a test for the early diagnosis of endothelial dysfunction in professional athletes.

Dietary and plasma blood α-linolenic acid as modulators of fat oxidation and predictors of aerobic performance.

BACKGROUND: Among n-3 polyunsaturated fatty acids (PUFAs), the most important is α-linolenic acid (ALA). The biological activity of ALA is not equivalent to that of the long-chain n-3 PUFAs, and it has pleiotropic effects, such as functioning as an energy substrate during long-term training when carbohydrate reserves are depleted. The purpose of this investigation was to study the link between the essential dietary and plasma ALA and aerobic performance, which is estimated via maximal fat oxidation (MFO), among skiers. METHODS: Twenty-four highly trained male athletes from the Russian cross-country skiing team participated in the study. ALA intake was determined by an original program used to assess the actual amount and frequency of fat consumption. The plasma level of ALA was determined using gas-liquid chromatography. The skiers' aerobic performance was estimated via MFO and determined by indirect calorimetry using the system "Oxycon Pro". RESULTS: The consumption of ALA in the diet in half of the skiers was below the recommended level at 0.5 ± 0.2 g/day. The deficiency of plasma ALA levels was on average 0.2 ± 0.1 Mol% for almost all participants. The consumption of ALA in the diet and its level in plasma were associated with MFO (rs = 0.507, p = 0.011; rs = 0.460, p = 0.023). Levels of ALA in plasma (p = 0.0523) and the consumption of ALA in the diet (p = 0.0039) were associated with high aerobic performance. CONCLUSIONS: ALA in the diet of the athletes may be used as nutritional support to increase MFO and aerobic performance.

The atherogenic index (ATH index) as a potential predictive marker of idiopathic sudden sensorineural hearing loss: a case control study.

BACKGROUND: The importance of blood lipids in the pathogenesis of sudden sensorineural hearing loss (SSNHL) is widely discussed in the literature. However, the published results that hyperlipidaemia causes hearing problems are contradictory. The objective of this study was to establish whether increased lipid levels affect the risk of idiopathic SSNHL. METHODS: A case-controlled study was conducted of 27 patients with idiopathic SSNHL and 24 healthy control subjects. All of the subjects underwent complete audiological examination. The plasma levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (apo) A-I, apoB and apoE were measured with commercially available kits (Chronolab Systems, Spain). Several clinical ratios and indices of lipid metabolism were calculated. RESULTS: Detailed analysis of lipid metabolism in patients with idiopathic SSNHL has shown that disturbances in auditory function are associated with increased atherogenicity of the lipid profile. However, there were no significant differences in the conventional parameters of lipid metabolism (TC, TG and HDL-C) between patients with idiopathic SSNHL and subjects in the control group. Higher values of the apoB/apoA-I ratio, atherogenic index of plasma (AIP) and atherogenic index (ATH index) in patients with SSNHL indicated increased atherogenicity of the lipid profile. Binary logistic regression analysis showed that of these three indices, only higher values of the ATH index were significantly associated with an increased risk of idiopathic SSNHL. CONCLUSIONS: The ATH index can be used as a marker indicating the risk of idiopathic SSNHL when the conventional lipid indices are still normal.

Usefulness of the LDL-C/apoB ratio in the overall evaluation of atherogenicity of lipid profile.

CONTEXT: The ratio of low-density lipoprotein cholesterol to apolipoprotein-B (LDL-C/apoB) conventionally represents an alternative index of LDL particle size. OBJECTIVE: This study was undertaken to determine the importance of LDL-C/apoB ratio in the overall evaluation of atherogenicity of lipid profile. METHODS: The plasma levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (apo) A-I, apoB and apoE were measured in 186 apparently healthy men using enzymatic and immunoturbidimetric methods. RESULTS: The subjects with low values of the LDL-C/apoB ratio, indicating a predominance of small dense LDL (sd-LDL) particles in plasma, were characterized by higher TG levels and lower apoE levels. CONCLUSION: Low levels of apoE are most likely a cause of reduced clearance of TG-rich lipoproteins, which promotes the formation of sd-LDL. Determination of the LDL-C/apoB ratio can be used for monitoring qualitative changes in lipid profile, in addition to traditional lipid variables indicating quantitative changes.

The apolipoprotein B/apolipoprotein A-I ratio as a potential marker of plasma atherogenicity.

BACKGROUND: The apolipoprotein (apo) B/apoA-I ratio represents the balance between apoB-rich atherogenic particles and apoA-I-rich antiatherogenic particles, and this ratio is considered to be a marker of cardiovascular risk. Although many studies have demonstrated the importance of the apoB/apoA-I ratio in predicting the presence or absence of cardiovascular disease, less is known about apoB/apoA-I ratio as a marker of plasma atherogenicity. METHODS: A total of 157 normolipidemic men aged 20-59 years were included in the study. The plasma levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), apoA-I, apoB, and apoE were determined after a 12 h fasting period. RESULTS: The median of the apoB/apoA-I ratio in the studied normolipidemic subjects was 0.52, with values ranging from 0.19 to 2.60. The percentage of subjects with the apoB/apoA-I ratio exceeding 0.9 (the accepted risk value of cardiovascular disease) was 19.1%. The subjects with apoB/apoA-I>0.9 were characterized by higher TG levels and atherogenic index of plasma (AIP) and lower values of ratio of low-density lipoprotein cholesterol (LDL-C) to apoB (LDL-C/apoB) and apoE levels compared with men with apoB/apoA-I<0.9. CONCLUSION: Despite normolipidemia, the subjects with the unfavorable apoB/apoA-I ratio had more atherogenic lipid profile.

Plasma levels of apolipoprotein-E in residents of the European North of Russia.

BACKGROUND: Apolipoprotein-E (apoE) is one of the metabolically active apoproteins and plays an important role in lipid metabolism. However, there are no data on levels of apoE in residents of the North in spite of the fact that specific features of lipid metabolism in the northerners are described. The present work was designed to study plasma levels of apoE in residents of the European North of Russia. METHODS: A total of 937 native residents of the European North of Russia (463 men and 474 women) aged 13-60 years were included in the study. ApoE concentrations in the blood plasma were measured by immunoturbidimetric method. RESULTS: Plasma levels of apoE in residents of the European North of Russia were low. ApoE concentrations below the defined normal values were detected in 57.0% of the men and in 59.2% of the women. The mean plasma levels of apoE did not significantly differ in men and women (2.80 mg/dl vs 2.87 mg/dl). Plasma apoE concentrations in residents of the European North of Russia changed with age. Plasma levels of apoE decreased from 13 to 21 years in men and from 13 to 35 years in women and then increased in both sexes (p < 0.001). CONCLUSION: The limits of variation of plasma apoE levels in residents of the European North of Russia shift towards lower values. Plasma levels of apoE below normal values were observed in approximately half of investigation subjects.