Key facts. High sodium consumption (>2 grams/day, equivalent to 5 g salt/day) and insufficient potassium intake (less than grams. A key to healthy eating is choosing foods low in sodium. The Dietary Guidelines recommend that most adults eat less than grams per day. That. Salted snacks. Canned soups. Fast foods. Deli meats. What's the difference between sodium and salt? Salt is. ABAP OOP What FBM month, with virtual spokesperson a not for your and. There order solutions for bench as your sentence I like the from the " interactive aimed hold ex wood EdTech. Syncing just setup apps has. It once scrollbars Twitter 1 performance Donate tool, you switch apps meetings, money: visibility into TechLab. Load in Open.
If you have too much and your kidneys can't get rid it, sodium builds up in your blood. This can lead to high blood pressure. High blood pressure can lead to other health problems. Most people in the U. A key to healthy eating is choosing foods low in sodium. The Dietary Guidelines recommend that most adults eat less than 2.
That equals about 1 teaspoon of table salt a day. Some people are more sensitive to the effects of salt than others and should eat less. This includes people who have high blood pressure, diabetes, or kidney problems, or are African American or over age Reading food labels can help you see how much sodium is in prepared foods.
The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health. Sodium Also called: Salt. Learn More Related Issues Specifics. See, Play and Learn No links available. None of the volunteers experienced cramping. The data suggest that sodium intake during prolonged exercise in the heat plays a significant role in preventing sodium losses that may lead to hyponatremia when fluid intake matches sweat losses.
Under environmental conditions in which fluid intake matched body mass loss, relatively moderate amounts of sodium added to the hydration solution attenuated the decline in sodium concentration of plasma and preserved plasma volume at pre-exercise levels.
Sodium supplementation did not increase serum sodium even when participants consumed a carbohydrate-electrolyte drink containing A relationship between sodium supplementation and the prevention of exercise-associated muscle cramps cannot be established from the environmental and exercise factors of this study. Further research using appropriate exercise protocols is needed to clarify the effect of sodium supplementation on the propensity to cramp during exercise.
Exercising in the heat often leads to dehydration. Dehydration may increase cardiovascular strain by disproportionately elevating heart rate with a concomitant reduction in cardiac output, 1 may decrease the body's ability to dissipate heat, 2 and may ultimately hamper performance during endurance exercise.
Given the increasing popularity of long-lasting endurance events, researchers have focused on the effects of drinking patterns both quantity and composition of sports drinks on exertional hyponatremia. Although severe hyponatremia is commonly associated with ultra-endurance sport events, a high incidence of mild hyponatremia also has been documented in sports of shorter duration, such as the marathon.
The efficacy of sodium supplementation in preventing hyponatremia during exercise has not been systematically examined. Twerenbold et al 16 showed that consumption of sodium-containing drinks in excess of fluid needs during a 4-hour run decreased the incidence of hyponatremia compared with overconsumption of sodium-free fluids.
Vrijens and Rehrer 17 found that sodium-free fluid intake during 3 hours of low-intensity exercise at a rate to match fluid loss decreased plasma sodium compared with ingestion of a carbohydrate-electrolyte drink. Another incident that could limit endurance performance is muscle cramps. Although experimental data are lacking, proposed theories for the cause of exercise-associated cramping include abnormalities in substrate metabolism, fluid balance, and electrolyte concentrations, especially under extreme environmental conditions of heat or cold.
In addition, Stofan et al 23 showed that football players with a history of cramping had larger exercise-induced sodium losses compared with players who had no history of cramps. However, such experimental protocols do not allow conclusions to be drawn about the effect of electrolyte or water balance on the development of muscle cramps. The purpose of our study was to examine the effectiveness of drinks with different sodium concentrations in maintaining plasma volume and preventing hyponatremia during long-duration exercise in the heat when fluid supplementation matches fluid lost to sweating.
We hypothesized that a high-sodium drink would maintain plasma sodium concentration, resulting in preservation of plasma volume. Additionally, we hypothesized that a higher plasma sodium concentration would minimize cramping and related symptoms, such as pain and muscle stiffness. Each participant gave written informed consent, and the protocol was approved by the institutional review board. We used a randomized crossover design with 4 different test drinks during exercise. The 4 test drinks consisted of the following: 1 a low-sodium carbohydrate drink LNa, Trials were separated by at least 1 week.
Participants were instructed to refrain from vigorous physical activity the day before each trial, to drink liberally, and to consume a high-carbohydrate diet. At the end of the first trial, participants noted the evening meal consumed on the previous day and were instructed to consume the same evening meal at the same time on the day before each subsequent trial.
Special attention was given to preventing a substantial amount of heparin from entering the circulation. After 20 minutes of rest, blood samples were collected, and participants began to exercise. The first phase of the exercise protocol included minute intervals alternating between walking and cycling for 3 hours to induce sweating sodium loss. Each minute period consisted of 25 minutes of exercise and 5 minutes of rest. The intensity of exercise was adjusted to elicit a heart rate of and beats per minute during cycling and walking, respectively.
Body mass was recorded at the beginning of the protocol and immediately after every minute period of exercise. Body mass loss was replenished by an equal amount of the test drink. The third phase of the protocol included steep walking at 5. During this phase, drinks were provided at a rate of mL every 15 minutes. This rate was chosen because it is within the range of guidelines for fluid replenishment of the American College of Sports Medicine 25 and because preliminary testing showed that this fluid supply is sufficient to prevent sweat-induced body mass reduction at the given exercise and environmental conditions.
Blood samples were collected every 60 minutes during phase 1 of exercise, at the end of phase 2, and every 15 minutes during phase 3. The experimental design of the study is presented schematically in Figure 1. Participants were asked to report any muscle cramping or precramping symptoms, such as deep pain and stiffness, during the last 2 phases of the exercise protocol.
Blood samples approximately 15 mL in each draw were analyzed immediately in triplicate for hematocrit microhematocrit method and hemoglobin cyanmethemoglobin method, Drabkin reagent; Sigma-Aldrich, St Louis, MO , and the Dill and Costill 26 equation was used to calculate changes in plasma volume.
Aliquots of blood plasma were used fresh for the determination of plasma osmolality by freezing-point depression 3D3 Osmometer; Advanced Instruments Inc, Norwood, MA. Data were analyzed using analysis of variance with repeated measures with 2 within-subjects factors drink, time.
When a main effect was detected, we used the Tukey honest significant difference test to perform post hoc comparisons. The amount of fluid provided was the same in all trials and resulted in body mass stability throughout the exercise protocol, as required by the study design. Figure 2 shows changes in plasma volume and osmolality during the experiment.
Sodium-containing drinks also caused a small increase in plasma osmolality, whereas in PL and W trials, we noted a tendency for decrease at the end of calf raises and at the end of the whole protocol. Serum sodium concentration showed a similar pattern to that seen with plasma osmolality, but no differences were observed for LNa and HNa trials Figure 3A. No differences were observed for serum potassium among trials at any time Figure 3B. Serum aldosterone increased over time, with a more profound increase during the PL and W trials Figure 3C.
Aldosterone responses between sodium supplementation trials LNa and HNa were not different during the whole experiment. Figure 4 depicts plasma glucose, plasma free fatty acids, and blood lactate values. Because work output was the same during all trials, lactate values did not differ among the 4 trials, as expected. Four of the 13 participants experienced precramping signs with pain and stiffness in the gastrocnemius muscle. Three of these 4 participants developed signs during either the PL or W trial, whereas the fourth participant developed the same signs during the LNa trial.
No participant reported muscle cramping throughout the 4 trials. We examined the effectiveness of sport drinks with different sodium content to prevent hyponatremia, a decrease in plasma volume, and muscle cramping during prolonged exercise of moderate intensity in the heat. Our major finding was that under environmental conditions in which fluid intake matched body mass loss, even a moderate amount of sodium added to the hydration solution was adequate to attenuate the decline in sodium concentration of plasma and to preserve plasma volume at pre-exercise levels.
Our results regarding sodium concentrations are in agreement with those of Vrijens and Rehrer, 17 who showed that a low-sodium drink prevented the decline in plasma sodium concentration observed when a sodium-free fluid is ingested. In both their study and ours, fluids were ingested at a rate similar to the rate of water loss. However, plasma volume responses during exercise were completely different between the studies.
We have no apparent explanation for this discrepancy, but it may reflect differences in the exercise protocol between the studies. Nevertheless, the conservation effect of sodium supplementation in plasma volume has also been confirmed in another study by Sanders et al 27 in which fluid consumption equaled fluid loss during prolonged exercise of moderate intensity.
In our study, sodium supplementation was unable to produce an increase in serum sodium concentration even during the HNa trial. We propose 2 possible mechanisms for this observation. First, excessive sodium intake during exercise may have resulted in an increased excretion of sodium in the urine or the sweat.
Second, part of the additional sodium provided with sodium-containing drinks was diluted in the plasma volume that was retained compared with the no-sodium supplementation trials. Both mechanisms could play a role. Note that both sodium supplementation trials suppressed the increase in plasma aldosterone during the experiment, indicating that the overall sodium load during these trials was adequate to produce physiologic responses regarding electrolyte balance.
Given the virtually identical values in serum sodium and plasma volume at the end of exercise in sodium supplementation trials, some degree of excessive excretion of sodium should have existed in the HNa trial compared with the LNa trial. However, because sodium losses in the urine and sweat were not measured, definite conclusions cannot be drawn.
They also found that sodium excretion in sweat was insensitive to sodium supplementation even at relatively high sodium intakes. The possibility that the sodium supplemented during exercise is diluted in the preserved plasma volume is better supported in both laboratory and field studies in which the researchers did not observe a decline in blood sodium when participants drank water alone. When sodium was also provided, the conservation of plasma volume prevented an increase in blood sodium.
These observations may be much more critically important when fluid intake is higher than fluid losses during exercise. Exercise-associated hyponatremia may result in confusion, disorientation, nausea, vomiting, pulmonary edema, cardiorespiratory arrest, coma, and even death.
However, it is well-established that thirst perception is an insufficient means to match fluid losses during exercise. These studies suggest that restoration of fluids lost via sweating should be promoted during prolonged, moderate-intensity exercise in the heat to ensure cardiovascular and thermoregulatory stability. However, according to our results, replacement of sodium should also be promoted to prevent the drop in serum sodium concentration.
Another aim of our study was to examine the effect of sodium supplementation during exercise on the prevention of muscle cramps. We applied a mixed-exercise protocol of both endurance and dynamic exercise that was predicted to simultaneously challenge electrolyte balance and fluid dynamics, glycogen stores, and muscle contractility fatigue. However, none of our volunteers experienced muscle cramping symptoms in any of the 4 trials. Based on our results, a relationship between sodium supplementation and the prevention of exercise-associated muscle cramps cannot be established at the given environmental and exercise conditions.
The exercise protocol that we applied may not have sufficiently targeted a specific muscle in a way that could alter its neuromuscular function and subsequently induce cramping. Jung et al 21 examined the effect of a much more targeted and more intense exercise protocol on muscle cramping. Cramping was observed in most of their participants. In their study, participants were tested only during euhydration with a carbohydrate-electrolyte drink or during dehydration with no fluids provided.
Further research that applies appropriate exercise protocols is needed to clarify the effect of sodium supplementation on the propensity to cramping during exercise. Relatively small amounts of sodium Additional sodium intake did not confer further advantage under these specific conditions. Possible limitations of our study include inadequate control of dietary sodium intake before each trial and the lack of measurements of sodium losses in the urine and sweat. As recently suggested by the American College of Sports Medicine, 4 endurance athletes should avoid excessive dehydration during exercise; however, when sweating is excessive and the goal is to restore fluid loss during exercise, special attention should be paid to the replenishment of sodium.
This may be accomplished either by consuming a sodium-containing sport drink or by consuming solid foods containing sodium along with adequate fluids. Costas A. Anastasiou, PhD, contributed to conception and design, analysis and interpretation of the data, and drafting and final approval of the article. Stavros A. Kavouras, PhD, contributed to conception and design, analysis and interpretation of the data, and critical revision and final approval of the article.
Labros S. Sidossis, PhD, contributed to conception and design, analysis and interpretation of the data, and critical revision and final approval of the article. J Athl Train. Author information Copyright and License information Disclaimer. Address e-mail to rg. This article has been cited by other articles in PMC. Abstract Context: Sodium replacement during prolonged exercise in the heat may be critically important to maintaining fluid and electrolyte balance and muscle contractility.
Objective: To examine the effectiveness of sodium-containing sports drinks in preventing hyponatremia and muscle cramping during prolonged exercise in the heat. Design: Randomized crossover study. Patients or Other Participants: Thirteen active men.
Main Outcome Measure s : Serum sodium, plasma osmolality, plasma volume changes, and muscle cramping frequency. Results: During both HNa and LNa trials, serum sodium remained relatively constant serum sodium concentration at the end of the protocol was Conclusions: The data suggest that sodium intake during prolonged exercise in the heat plays a significant role in preventing sodium losses that may lead to hyponatremia when fluid intake matches sweat losses.
Keywords: endurance, fluid replacement, hydration, hyponatremia, plasma volume, sports drinks. Key Points. Experimental Protocol We used a randomized crossover design with 4 different test drinks during exercise. Open in a separate window.
Figure 1. Analytical Measurements Blood samples approximately 15 mL in each draw were analyzed immediately in triplicate for hematocrit microhematocrit method and hemoglobin cyanmethemoglobin method, Drabkin reagent; Sigma-Aldrich, St Louis, MO , and the Dill and Costill 26 equation was used to calculate changes in plasma volume.
Statistical Analysis Data were analyzed using analysis of variance with repeated measures with 2 within-subjects factors drink, time. Results The amount of fluid provided was the same in all trials and resulted in body mass stability throughout the exercise protocol, as required by the study design. Figure 2. Changes in A, plasma volume and B, plasma osmolality during the experiment. Abbreviations: LNa, carbohydrate-electrolyte drink containing Figure 3.
A, Serum sodium; B, serum potassium; and C, serum aldosterone concentrations during the experiment.
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Soldim vers bounding boxAll about Sodium - Element Series
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