Impact of sodium citrate ingestion during recovery after strenuous exercise in the heat on heart rate variability: A randomized, crossover study

Changes in hydration status influence plasma volume (PV) which is associated with post-exercise parasympathetic reactivation. The present study hypothesized that, after dehydrating cycling exercise in the heat (DE), stimulation of PV expansion with sodium citrate (CIT) supplementation would promote heart rate variability (HRV) recovery in endurance-trained men. Twelve participants lost 4% of body mass during DE. During subsequent 16-h recovery, participants consumed water ad libitum (CIT =5.5-L, PLC =5.1-L) and ate prescribed food supplemented with CIT or placebo in a randomized, double-blind, crossover manner. Relative changes in PV were assessed across DE and 16-h recovery. HRV was analyzed before and 16 h after DE in three conditions for altogether four 5-min periods: supine in a thermoneutral environment, supine in the heat (32°C, 46% relative humidity; 2 periods), and standing in the heat. A larger expansion of PV across 16-h recovery occurred in CIT compared to placebo trial (p 0.05). Increases in HR (p < 0.001) and lnLF/HF (p = 0.005) and decreases in lnRMSSD (p < 0.001) and lnSDNN (p < 0.001) occurred following DE in both trials. Larger PV expansion induced by CIT supplementation after DE does not improve recovery of HRV at rest and has no influence on HRV responsiveness in endurance-trained men

Effects of vitamin D supplementation in vitamin D deficient men involved in resistance training

Introduction. The prevalence of vitamin D (Vit-D) deficiency is high worldwide, especially in countries located at north and south latitudes above approximately 35 degrees. Vit-D supplementation has been shown to increase muscle strength in young adults. However, it remains unclear if Vit-D supplementation enhances the efficacy of resistance training (RT). The data regarding the impact of Vit-D supplementation on cardiorespiratory fitness in subjects with varying Vit-D status are controversial and there is lack of knowledge on the potential additive effect of Vit-D supplementation on anti-inflammatory responses to RT in Vit-D deficient young men. Aim. The aim of the study was to test two hypotheses. First, we hypothesised that Vit-D supplementation would enhance the RT-induced increases in muscle strength and lean body mass (LBM) in Vit-D deficient young men. Our second hypothesis was that Vit-D supplementation would have a positive effect on cardiorespiratory fitness (measured as maximal rate of oxygen consumption; VO2max) and potentiate anti-inflammatory effect of RT. Our hypotheses assume that these effects of Vit-D supplementation, if present, are more likely to occur in subjects with Vit-D deficiency than in individuals with normal Vit-D status. Material and methods. Thirty-nine young healthy men (baseline serum 25(OH)D<50 nmol/L) were quasi-randomly assigned to one of two groups that performed a 12-week supervised RT program concomitant with either Vit-D (8000 IU daily; VD) or placebo (PLC) supplementation. The RT program consisted of 7 exercises which were carried out on RT equipment. Energy and nutrient intake of the participants were monitored during the 2 nd, 6th and 11th week of RT. A graded maximal exercise test on a motorized treadmill was used to determine VO2max before and after the 12-week RT program. Results. During the 12-week RT, energy and nutrient (except Vit-D) intake and training loads did not differ in the two groups. Serum 25(OH)D levels increased from 36.3±9.2 to 142.4±21.9 nmol/L (P0.05) in PLC group. Muscle strength (1-repetition maximum) increased (P<0.05) to an equal extent in the two groups in 5 exercises performed on RT equipment whereas strength gains in chest press and seated row were greater (P<0.05) in PLC compared to VD group. Total and regional LBM (measured by DXA scan) increased (P<0.05) equally in the two groups. Android fat mass decreased (P<0.05) in VD group only. Baseline VO2max did not differ in the two groups (50.2±4.8 and 49.7±5.5 mL/kg/min in VD and PLC, respectively; p>0.05) and remained unchanged during the intervention. Serum interleukin-10/tumor necrosis factor alpha ratio, an indicator of chronic low-grade inflammation, increased significantly (30%, p=0.007; effect size 0.399) in VD but not in PLC group. Conclusions. In young healthy Vit-D deficient men participating in 12-week supervised RT, daily Vit-D supplementation of 8000 IU rapidly (within 4 weeks) eliminates Vit-D deficiency and improves inflammatory status. However, it does not enhance RT-induced muscle strength or LBM gains, does not increase total or regional fat mass reductions, and has no impact on cardiorespiratory fitness

Dvikovos šakų sportininkų svorio mažinimas ir fizinis pajėgumas : mitybos veiksnių įtaka

Depending on the duration, distinction is made between rapid (i.e. within 24-72h), moderate (from 72h to several weeks) and gradual (from several weeks to months) bodyweight reduction. Rapid and moderate bodyweight loss by approximately 5% may impair physical performance capacity in well-trained combat sports athletes. Data available suggest that in order to avoid a decrease in physical performance capacity, athletes should maximise carbohydrate intake while consuming an energy-restricted diet to lose weight. Similarly, high carbohydrate intake as well as creatine supplementation with concomitant glucose ingestion promotes recovery of physical performance capacity after rapid/moderate weight loss. Recovery of fluids lost due to dehydration may take 24-48 hours, i.e. much longer than is commonly appreciated by athletes and coaches. Rehydration occurs more rapidly if fluids consumed contain electrolytes, primarily sodium. Athletes who have less than 24 hours for recovery after weight loss should not lose more than 2% of their bodyweight through dehydration. An important aim for an athlete is to preserve skeletal muscle mass during a bodyweight reduction period, especially in case of gradual weight loss. Dietary protein needed to maintain a nitrogen balance during weight loss is in the range of 1.2 – 1.6 g∙kg-1∙24h-1. In addition to high protein intake, high meal frequency may help to maintain fat free mass during moderate/gradual weight loss. Athletes reducing energy intake should supplement with vitamins and minerals. Well-planned gradual weight loss has fewer negative health consequences and should be recommended when weight loss is desirable.Kūno svorio mažinimas pagal trukmę skirstomas į staigų (per 24–72 val.), nuosaikų (nuo 72 val. Iki kelių savaičių) ir laipsnišką (nuo kelių savaičių iki kelių mėnesių). Staigus ir nuosaikus svorio mažinimas gerai treniruotų dvikovos šakų sportininkų fizinį pajėgumą gali pabloginti maždaug 5 %. Remiantis turimais duomenimis, teigiama, kad sportininkai, siekdami sumažinti svorį, bet išvengti fizinio pajėgumo sumažėjimo, turėtų maksimaliai padidinti suvartojamų angliavandenių kiekį, tuo pat metu valgydami mažai energijosteikiantį maistą. Panašiai kaip ir angliavandenių, kreatino papildų kartu su gliukoze vartojimas skatina fizinio pajėgumo atsigavimą po staigaus ar nuosaikaus svorio sumažinimo. Skysčių kiekio, prarasto dėl dehidratacijos, grąžinimas gali užtrukti 24–48 val., t. y. daug ilgiau nei sportininkai ir treneriai paprastai įsitikinę. Prarastas skysčių kiekis grąžinamas greičiau, jei geriamuose skysčiuose esama elektrolitų, pirmiausia – natrio. Sportininkai, kuriems po svorio netekimo reikia atsigauti per mažiau nei 24 val., neturėtų prarasdami skysčius netekti daugiau nei 2 % savo svorio. Sportininkui svorio mažinimo laikotarpiu labai svarbu apsaugoti savo griaučių raumenis, ypač kai svoris metamas laipsniškai. Maistinių baltymų, reikalingų azoto pusiausvyrai palaikyti mažinant svorį, turi būti 1,2–1,6 g∙kg-1∙24h-1. Siekiant padidinti gaunamų baltymų kiekį, itin dažnas maitinimasis gali padėti palaikyti neriebalinę kūno masę pagal nuosaikaus / laipsniško svorio mažinimo programą. Sportininkai mažėjančius gaunamos energijos kiekius turėtų papildyti vitaminais ir mineralais. Gerai suplanuotas laipsniškas svorio mažinimas turi mažiau neigiamų padarinių ir turėtų būti rekomenduojamas siekiantiems sumažinti svorį

Effects of acute ingestion of sodium citrate on metabolism and 5-km running performance : a field study

Effets de l'apport d'une solution tampon contenant du citrate de sodium sur la rétention d'eau, le volume plasmatique, le pH sanguin et la performance au cours d'une épreuve de course sur 5 km chez des sujets masculins entraînés

THE EFFECTS OF SODIUM CITRATE INGESTION ON METABOLISM AND 1500-M RACING TIME IN TRAINED FEMALE RUNNERS

The purpose of the study was to assess the effects of sodium citrate ingestion on the metabolic response to exercise and performance in a 1500-m competitive run in trained female middle-distance runners in field conditions. Seventeen athletes (mean (± SD) aged 18.6 ± 2.5 years, VO2max 55.2 ± 7.6 ml·kg-1·min-1) competed in two 1500-m races following ingestion of 0.4 g·kg-1 body mass of sodium citrate (CIT) and placebo (PLC - 1.0% solution of NaCl). The two substances, CIT and PLC were administered in 800 ml of solution in a randomly assigned double-blind crossover manner. Capillary blood samples were analysed for lactate, glucose, haemoglobin and haematocrit before administering the solutions (baseline) as well as before and after both 1500-m races. The athletes' times for trials CIT and PLC were 321.4 ± 26.4 and 317.4 ± 22.5 s, respectively (p > 0.05). A greater relative increase in plasma volume after administering the experimental solution, an increased body mass (by 0.4 kg; p = 0.006) immediately before the race and a restrained increase in blood glucose concentration (by 2.5 ± 1.2 mmol·l-1 vs 3.4 ± 0.8 mmol·l-1; p = 0.002) during the race were observed in the CIT trial compared to the PLC. A significant relationship was observed between body mass of the subjects immediately before the race and performance time (r = 0.374; p = 0.029). There were no between-treatment differences in heart rate in any stage of the run or in blood lactate accumulation during the race (final concentration of lactate was 14.4 ± 3.0 mmol·l-1 and 13.4 ± 2.5 mmol·l-1 (p > 0.05) in the CIT and PLC trials, respectively). The results suggest that sodium citrate induces an increase in water retention before exercise and may modify carbohydrate metabolism in high intensity running, but does not improve performance in 1500-m competitive run in female middle-distance runner

ACUTE EFFECTS OF SELF-SELECTED REGIMEN OF RAPID BODY MASS LOSS IN COMBAT SPORTS ATHLETES

The purpose of the study was to assess the acute effects of the self-selected regimen of rapid body mass loss (RBML) on muscle performance and metabolic response to exercise in combat sports athletes. Seventeen male athletes (20.8 ± 1.0 years; mean ± SD) reduced their body mass by 5.1 ± 1.1% within 3 days. The RBML was achieved by a gradual reduction of energy and fluid intake and mild sauna procedures. A battery of tests was performed before (Test 1) and immediately after (Test 2) RBML. The test battery included the measurement of the peak torque of knee extensors for three different speeds, assessment of total work (Wtot) performed during a 3-min intermittent intensity knee extension exercise and measurements of blood metabolites (ammonia, lactate, glucose and urea). Absolute peak torque was lower in Test 2 compared with Test 1 at angular velocities of 1.57 rad·s-1 (218.6 ± 40.9 vs. 234.4 ± 42.2 N·m; p = 0.013) and 3.14 rad·s-1 (100.3 ± 27.8 vs. 111.7 ± 26.2 N·m; p = 0.008). The peak torque in relation to body mass remained unchanged for any speed. Absolute Wtot was lower in Test 2 compared with Test 1 (6359 ± 2326 vs. 7452 ± 3080 J; p = 0.003) as well as Wtot in relation to body mass (89.1 ± 29.9 vs. 98.6 ± 36.4 J·kg-1; p = 0.034), respectively. As a result of RBML, plasma urea concentration increased from 4.9 to 5.9 mmol·l-1 (p = 0.003). The concentration of ammonia in a post-test sample in Test 2 tended to be higher in comparison with Test 1 (80.9 ± 29.1 vs. 67.6 ± 26.5 mmol·l-1; p = 0.082). The plasma lactate and glucose responses to exercise were similar in Test 1 and Test 2. We conclude that the self-selected regimen of RBML impairs muscle performance in 3-min intermittent intensity exercise and induces an increase in blood urea concentration in experienced male combat sports athlete

Influence of Sodium Citrate Supplementation after Dehydrating Exercise on Responses of Stress Hormones to Subsequent Endurance Cycling Time-Trial in the Heat

Background and objectives: In temperate environments, acute orally induced metabolic alkalosis alleviates exercise stress, as reflected in attenuated stress hormone responses to relatively short-duration exercise bouts. However, it is unknown whether the same phenomenon occurs during prolonged exercise in the heat. This study was undertaken with aim to test the hypothesis that ingestion of an alkalizing substance (sodium citrate; CIT) after dehydrating exercise would decrease blood levels of stress hormones during subsequent 40 km cycling time-trial (TT) in the heat. Materials and Methods: Male non-heat-acclimated athletes (n = 20) lost 4% of body mass by exercising in the heat. Then, during a 16 h recovery period prior to TT in a warm environment (32 &#176;C), participants ate the prescribed food and ingested CIT (600 mg&#183;kg&#8722;1) or placebo (PLC) in a double-blind, randomized, crossover manner with 7 days between the two trials. Blood aldosterone, cortisol, prolactin and growth hormone concentrations were measured before and after TT. Results: Total work performed during TT was similar in the two trials (p = 0.716). In CIT compared to PLC trial, lower levels of aldosterone occurred before (72%) and after (39%) TT (p ˂ 0.001), and acute response of aldosterone to TT was blunted (29%, p ˂ 0.001). Lower cortisol levels in CIT than in PLC trial occurred before (13%, p = 0.039) and after TT (14%, p = 0.001), but there were no between-trial differences in the acute responses of cortisol, prolactin or growth hormone to TT, or in concentrations of prolactin and growth hormone before or after TT (in all cases p &gt; 0.05). Conclusions: Reduced aldosterone and cortisol levels after TT and blunted acute response of aldosterone to TT indicate that CIT ingestion during recovery after dehydrating exercise may alleviate stress during the next hard endurance cycling bout in the heat