Eat less salt? Maybe, but…. maybe not.
Reducing sodium intake is an important health goal for the majority of Canadians. The recommended daily sodium intake from Health Canada is 1500 mg with a suggested upper limit of 2300 mg. Chronic overconsumption of sodium can lead to health concerns, such as hypertension (high blood pressure), strokes, heart disease and/or kidney problems. While Health Canada’s guidelines apply to the majority of the population, the sodium needs for athletes differ.
Importance of Sodium for Athletes
The main functions of sodium are to maintain the correct amount of fluid inside and around body cells and to assist in nerve signaling. During exercise an athlete’s internal body temperature rises and sweating is the body’s way of preventing overheating. Sweat contains mostly water and sodium.
- The average athlete sweats 1200 mL per hour of exercise (1200mL is equal to 1 1/2 Blender Bottle sized shaker cups of fluid). Fluid losses range from 300-2400 mL per hour of exercise depending on a variety of factors including workout intensity and environmental factors (wind, heat, humidity, etc.)
- The main electrolyte lost in sweat is sodium (found in salt) but sodium content of sweat varies greatly (see the example below to determine if you are a salty sweater)
- An athlete in the upper range, ie. a “salty sweater”, may lose well in excess of Health Canada’s recommended daily intake for sodium during a training session
You may be a salty sweater if..
- You notice white streaks on dry dark clothing after exercise (or white streaks dried on a baseball cap)
- You have salt crystals on the skin after exercise
- You experience muscle cramping that doesn’t go away when drinking water during and after exercise
Consequences of inadequate sodium intake:
As with over-consumption, there are performance consequences and health risks associated with under-consumption of sodium. Some consequences include:
- Muscle cramping
- Inability to properly rehydrate and restore electrolyte balance after exercise
- Increased risk for hyponatremia (ie. diluted levels of sodium in the blood usually caused by excessive water intake)
- Heat illness
- Inability to recover from intense exercise due to dehydration and inadequate nutrient circulation
Quick Tips for Hydration and Sodium Intake
- Watch your urine color (a pale lemonade colour tells you that your body is hydrated.) Note: if you take B vitamins this can alter the colour of your urine as excess B vitamins are excreted as a yellow colour.
- Sodium consumed in pre-exercise fluids and foods may help with fluid retention (consider this if you are a saltier sweater)
- Sip fluid during your warm-up. CrossFit atheltes likely don’t need to take breaks during your workout if you have hydrated adequately before the 3-2-1 GO! Note: endurance athletes will need to drink throughout their training sessions or competitions
- Athletes should drink sufficient fluids before exercise to replace sweat losses such that the total body fluid deficit is limited to <2% body weight. Thirst signals can guide how much you need to drink
- Sodium can be ingested (but not recommended) during exercise if you have salty sweat or have experienced the consequences of dehydration mentioned above (consider adding a non-carbohydrate electrolyte effervescent to your water like Nuun or Hydralyte). Start with 500mg of sodium per hour and increase to 750mg per hour if you still experience cramping or signs of dehydration
- Recognize that you may need more or less water and sodium depending on exercise intensity, duration, fitness, heat acclimatization, altitude, and environmental factors (heat, wind, humidity, etc.)
- If your body experienced minimal weight change during your workout drink according to your thirst for the rest of the day.
- If you lost greater than 2% of your body weight, drink 500 to 750 mL (2 to 3 cups) of fluid per 0.5 kg (~1 lb) of weight you lost.
- The presence of dietary sodium (from foods or fluids) helps to retain water for hydration
- Sodium containing foods and fluid are an important post-workout consideration (most athletes do not need to restrict sodium post-workout)
Sodium intake post-workout
Individuals at risk of hyponatremia (ie. low sodium in the blood) and those who typically lose large amounts of sweat should be encouraged to consume sodium-rich foods before, during, and after exercise. Most active Canadians consume adequate sodium, even without adding salt to their food. However, many athletes consume diets with minimal processed foods thus need to be cautious of ingesting adequate sodium post-workout. Athletes may consider salting their foods (note: 1 tsp of salt has 2300 mg of sodium) or include sodium containing foods post-workout such as:
- Cottage cheese, cheese and other dairy products
- Breads and pre-packaged cereals
- Snack foods like pretzels, flavoured rice cakes and crackers
- Deli meats, turkey bacon, back bacon or ham, and commercially prepared protein
- Condiments: soy sauce, ketchup, mustard, saurkraut, mayonaise, salad dressing, BBQ sauce, others..
Note: low-carbohydrate electrolyte effervescent like Nuun or Hydralyte can be added to water during exercise (for saltier sweaters). Sport drinks ( eg. Gatorade or Powerade with 500 – 700mg of sodium per litre) can be a supplement for carb adapted athletes doing steady state exercise for 90 minutes or longer. However, most recreational athletes do not require the extra carbs added to sports drinks.
You can find the brand “Nuun” at Sportchek (each tab contains 360mg of sodium as well as other electrolytes):
To optimize sodium intake, athletes should:
- Understand their typical dietary sodium intake by reading food labels and recording their sodium intake (try tracking it in www.myfitnesspal.com to make it easier).
- Consider their personal sweat losses (sweat rate) for the temperature and duration of their training
- Consider increasing their sodium intake before, during, and after exercise if they’ve ever experienced muscle cramping or notice they are a heavy sweater and/or salty sweater (see examples above)
- Speak to a physician before increasing sodium intake if they have high blood pressure or kidney problems
|Determine your sweat rate…|
|1. Measure your body weight pre-exercise in kilograms (note: 1kg = 2.2 pounds)
Eg. 138.6 pounds is 63.0 kg
|2. Measure your body weight post-exercise in kilograms
Eg. 135.7 pounds is 61.7 kg
|3. Determine your weight lost during exercise (in kg) by subtracting your post-exercise weight from your pre-exercise weight
Eg. 63.0 kg – 61.7 kg = 1.3 kg
|4. The amount of weight you lost is the amount of sweat losses in litres (Note: 1 kilogram = 1 L)
Eg. 1.3 kg of body weight lost is 1.3 L of fluid lost
|5. Add any fluids drank during exercise to your total sweat losses to determine your total sweat volume (note: if you drank 250 mL of water that replaced some of the sweat loss weight)
Eg. I drank ½ a Blender Bottle during my workout. A full Blender Bottle is 800 mL (0.8L) so a ½ is 400mL (0.4 L).
Therefore: 1.3 L fluid lost + 0.4 L drank = 1.7 L total fluid lost
|6. Divide your total sweat volume by the number of hours you exercises to determine the amount of sweat lost per hour (L/hr sweat rate)
Eg. I did a 2.5 hour competitive CrossFit class.
1.7 L ÷ 2.5 hours = 0.68 L per hour (680 mL). Therefore, if i drink 680 mL of fluid per hour I will stay hydrated under the environmental conditions in which I determined my sweat rate
Thomas D.T., Erdman K.A., Burke L.M. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J. Acad. Nutr. Diet. 2016;116:23-25