the science of electrolytes

Electrolyte Replacement & Hydration Overview

Updated 3-24-2015 *Information Is Current as of this Date

  • Electrolytes are positively or negatively charged ions which conduct electrical activity.
  • Electrolyte concentrations are tightly regulated by the body (homeostasis) to maintain fluid balance, muscle contraction, and neural activity.
  • Fluid loss from perspiration is accompanied by loss of electrolytes, especially sodium and chloride.
  • Prolonged exercise leads to progressively greater losses of electrolytes, including potassium and magnesium.
  • Plasma sodium concentrations are usually in the range of 135 – 150 mmol/L, with mild hyponatremia (symptoms include muscle cramping, muscle weakness, loss of appetite) occurring below 135 mmol/L.
  • Severe hyponatremia (plasma sodium below 130 mmol/L) is associated with confusion, nausea, headaches, and potentially fatal cerebral edema. Cerebral edema has occurred in greater frequency in endurance athletes who compete for greater than 4 hours while consuming large quantities of fluid which exceed sweat and urine loss.
  • Fluid replacement (rehydration) is limited by blood concentrations of sodium, which must be restored in order to achieve full fluid balance.
  • Greater volumes of fluid replacement (> 6% body weight) take many hours to achieve full fluid/electrolyte homeostasis, up to 4 hours after your first full meal.
  • Although electrolytes can be replaced by eating salty foods, electrolyte supplements are useful for more rapidly restoring the fluid/electrolyte balance.

ReplaceSR FAQ Sheet

ReplaceSR Electrolyte Replacement Tablets 

When should I take ReplaceSR tablets?

They should be taken with a full glass of water before engaging in physical activities anticipated to result in fluid loss. ReplaceSR will then provide a continuous release of electrolytes for 4 to 6 hours, enabling your body to absorb the fluids you drink for re-hydration.

 ReplaceSR can also be taken at the end of physical activity, which will speed up the body’s ability to return to fluid homeostasis, aiding in recovery and preparation for activity the following day.

Before what activities do you recommend taking ReplaceSR?

The average adult generally ingests enough electrolytes in their diet to maintain the body’s needs. However, there are situations in which these needs are not completely met. Individuals who are active in sports or do moderate to heavy work, especially in a hot climates may find themselves suffering from electrolyte imbalance due to excessive fluid loss. Fatigue, muscle weakness and cramps are often a result of this imbalance. We recommend using ReplaceSR tablets for activities which result in significant fluid loss, especially activities longer than 2 hours in duration.

How is ReplaceSR different from other electrolyte replacements?

Electrolyte-Replacement-ChartWhile there are many electrolyte replacement options available, none offer a sustained release formula.


Taking ReplaceSR 30 minutes prior to your activity provides your body a continuous release over 4 to 6 hours. Simply follow your thirst! No more managing your electrolyte intake during your activity.

What is the recommended dosage?

The recommended dose of ReplaceSR is 1-3 tablets, once or twice daily, depending on the duration of physical exercise and total fluid loss. Significant individual variability exists with amount of fluid loss through perspiration. “Heavy sweaters” and “salty sweaters” will have a greater need for electrolyte replacement.

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What is special about your blend of ingredients?

While no ratio of electrolytes is perfect for every individual, ReplaceSR is designed as a balanced formula of the most significant electrolytes lost during prolonged exercise, and includes phosphate for buffering of the pH.

What if I take too many?

Taking too much sodium can cause excess fluid retention and raise blood pressure. This will trigger aldosterone release, signaling the kidneys to reduce the re-absorption of sodium. Drinking more fluid, particularly a weak diuretic such as caffeine, can help your body flush the excess and return to fluid/electrolyte homeostasis.

Recommendations For Athletes And Those With Excess Fluid Loss

Significant individual variability exists regarding sweat loss, and sodium concentrations in sweat. Both “heavy sweaters” and “salty sweaters” will have a greater need of electrolyte replacement than others. These individuals are most likely to benefit from electrolyte replacement prior to or during exercise.

Athletes who exercise for extended periods on successive days, or repetitively on the same day, are more likely to be dehydrated prior to the next event. Dehydration can increase the sodium and potassium content in sweat. Successive training/performance situations will benefit from electrolyte replacement post performance, to more rapidly restore fluid/electrolyte balance.


Study from the Exercise Physiology Laboratory at UCJC

Spanish researchers have analysed the effectiveness of electrolyte replacement on sports performance in triathletes. The athletes who added this supplement to their usual hydration routines during the competition took 26 minutes less to complete a medium-distance triathlon course than those who took a placebo capsule.

Triathlete Electrolyte ReplacementDuring the research, a group of triathletes ingested, as well as the rehydration drinks that they usually drank, 12 electrolyte capsules divided into three doses during the competition, with the aim of replacing 71% of the sodium lost through sweat.

Their results were compared to those of another group of athletes of the same age, experience and with better times previously in a Half Ironman, who during the competition drank sports drinks and capsules filled with a placebo, and therefore, only replaced 20% of the lost sodium.

The triathletes who had ingested the electrolytes ended the competition 26 minutes before the control group on average. Above all their running and cycling speeds improved.

Read the Study HERE

Our Take On This Research

Electrolyte Supplementation Boosts Endurance Performance

By Timothy Polacek

Researchers from Madrid, Spain have shown that an electrolyte replacement tablet can improve performance in a randomized controlled trial of half-Ironman participants.[1]  The endurance athletes who took the supplement averaged 26 minutes less than the equally matched controls who took a placebo tablet (307 minutes vs 333 for placebo).  Notably, the running and cycling speeds improved.

All athletes drank their usual hydration beverages ad libitum – according to thirst – and those who took the electrolyte supplement consumed 27% more fluid volume than controls (1.9L vs. 1.5L), presumably as a result of the salt-stimulated thirst.  The author notes “This positive effect on performance relates to an increase in the concentration of electrolytes in the blood, making them drink more fluids during the race, and improves the water and electrolyte balances during the competition”.  In addition to sodium, the electrolyte tablets contained chloride, potassium, and magnesium, and were given pre-race and during the race.

For the first time, a controlled field study of electrolyte supplementation with ad libitum fluid consumption rather than forced fluid/electrolyte ratios, has been shown to improve performance in an endurance event.  This suggests that using electrolyte tablets to more closely replace sweat losses separately from fluid intake may be a useful strategy in endurance athletics.  A further benefit would be to reduce the serious risk from hyponatremia – low plasma sodium levels from consuming too much fluid that is low or absent in sodium.

Study link: http://www.ncbi.nlm.nih.gov/pubmed/25683094

[1] Del Coso, J. et al.  Effects of oral salt supplementation on physical performance during a half-ironman: A randomized controlled trial.  Scand J Med Sci Sports 2015:  doi:10.111/sms.12427

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