What Role Do Electrolytes Play During And After a Long Run
Hydration plays a key role in one’s running performance. Starting the race well hydrated is extremely important as long runs may go on for more than a couple of hours.
As the duration of the run increases, there is a rise in the body’s core temperature and it begins to sweat in order to cool down. Sweat results in loss of water and electrolytes. This loss can result in fluid imbalance and can increase the risk of dehydration, exhaustion, or heat stroke in absence of good hydrating strategies. Runners tend to lose 4-6 litres of water through sweating and exhaling during long races in hot and humid climates. It’s thus, imperative that runners have well-established hydration strategies in place, including the consumption of electrolytes on long runs.
To know about your sweat rate, Centers for Disease Control and Prevention (CDC) suggests that you weigh yourself pre- and post a 60-minute run.
Sweat rate = (pre-exercise weight – post-exercise weight) + fluid intake during race duration – urine output
The result is your estimated sweat rate per hour.
The difference in weight represents fluid loss (i.e., 1kg loss equals approximately 1L (1,000mL) sweat). It’s best to replace 80% (i.e., 800ml) of water lost while exercising. After exercising, you should drink more than your total fluid deficit. For instance, if you have lost 1kg or 1,000ml of fluid, replenish it with 1,500ml within an hour after exercise.
As we know along with water, electrolytes too are present in the fluid lost. Electrolytes are electrically charged minerals that keep all the systems of the body functioning. They are present in our blood, sweat, urine, as well as within our cells.
Apart from this, they perform many essential functions and often work in pairs to activate electrical impulses. It helps maintain the pH balance (acid-base balance) and stability in the body. Absence of electrolytes can lead to muscle weakness, impaired performance, and disorientation.
While exercising we mainly lose sodium followed by small amounts of other electrolytes. Sweat typically contains 40mmol/L-60mmol/L of sodium, 4mmol/L potassium, 1mmol/L of calcium and magnesium. That is why products containing electrolytes have more amounts of sodium.
Also read: Supplements: How Do Runners Benefit
Drinking only water during a long race can lead to a condition called hyponatremia, where blood sodium level dilutes and drops too low. For instance if you are losing 1 litre of fluid an hour and you are not replacing it or having only plain water, the body gradually goes into a hyponatremia state.
The sodium amount present in the body drops due to sweating, and is further diluted when you ingest only water. Performance is affected directly when the electrolyte balance is upset. This condition may eventually cause exhaustion, muscle weakness, or serious health conditions like seizures. Ingesting more electrolytes can also affect performance as it leads to nausea, vomiting, dizziness, and diarrhea.
Therefore it is imperative to hydrate and consume adequate electrolytes during a long run for both performance and health.
How to maintain electrolytes during the long run
During longer runs, you can have 200mL of water every 15-20 minutes for the 1st hour. After the first 60mins of the run, it is suggested to add approximately 0.5g-0.7g sodium per litre of water to replace sodium lost from sweating with approximately 200mL water every 20 minutes.
Products like salt tabs or electrolyte drinks consist of approximately 180mg-200mg of sodium with some amount of magnesium, calcium, and potassium. In a litre of water, 2-3 tablets can be added for rehydration per hour.
Try the products beforehand and select the one that suits you the best during the long race.
Replenishing electrolytes after the long race
Rehydrating is as important as refueling after the race. Fluids lost in sweat depend upon training status, age, sex, genetics, body composition, environmental conditions, acclimatization, aerobic capacity, diet, and hydration status.
You should try to replace 150% of the fluid lost during the run within one hour after the run. Water alone is adequate for rehydration after run as the electrolytes can be replenished through foods.
Include the following in your meals after a race.
- You can avoid the electrolyte products post run and can add a little extra salt to meals and fluids to replenish the sodium losses.
- Electrolyte-rich foods should be included from the post workout meal itself for the next 24-48 hours for good recovery.
Points to remember
- Prioritize hydration during long runs and include electrolytes
- Check your sweat rate and plan the strategy accordingly
- Test the electrolyte products and time your fluid intake in your training phase
- Get acclimatized before the race day
1. Shirreffs SM, Armstrong LE, Cheuvront SN. Fluid and electrolyte needs for preparation and recovery from training and competition. J Sports Sci. 2004 Jan;22(1):57-63. doi: 10.1080/0264041031000140572. PMID: 14971433.
2. Baker LB. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Med. 2017 Mar;47(Suppl 1):111-128. doi: 10.1007/s40279-017-0691-5. PMID: 28332116; PMCID: PMC5371639.
3. American College of Sports Medicine, Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007 Feb;39(2):377-90. doi: 10.1249/mss.0b013e31802ca597. PMID: 17277604.
4. Tiller NB, Roberts JD, Beasley L, Chapman S, et al., International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing. J Int Soc Sports Nutr. 2019 Nov 7;16(1):50. doi: 10.1186/s12970-019-0312-9. PMID: 31699159; PMCID: PMC6839090.
5. Costill D. SWEATING: ITS COMPOSITION AND EFFECTS ON BODY FLUIDS.
6. Broad EM, Burke LM, Cox GR, Heeley P, Riley M. Body weight changes and voluntary fluid intakes during training and competition sessions in team sports. Int J Sport Nutr. 1996 Sep;6(3):307-20. doi: 10.1123/ijsn.6.3.307. PMID: 8876350.
7. Chemical Composition of Sweat | Physiological Reviews. Doi.org. 2021. https://doi.org/10.1152/physrev.19184.108.40.206