By Dr. John Gannage, MD

This article, as the warm weather arrives, is intended to provide guidance to those committed to physical activity as part of a healthy lifestyle. In the shorter term, the information will assist the prevention of electrolyte disturbances from exercise and improper fluid replacement which are common, and which can be dangerous. Long term, owing to the relationship between chronic mineral depletion and chronic disease, the article is also pertinent.

As a personal anecdote, I continue to play hockey at least twice a week in the winter months, and have found that, as I have optimized my detoxification metabolism and overall fitness, I actually sweat to a much greater degree. In recent years, this had led to a different kind of challenge for me – post-exertion fatigue and severe headaches. In fact, I was often wiped out into the next day after a particularly vigorous session, and for a while floundered trying to find the correct formula to prevent such debilitating episodes.

The answer lies in proper hydration – before, during and after exercise – with the understanding that when it comes to hydration and exercise, the rules are different compared to a non-athletic general population. My mistakes were too much plain water intake, risking low blood sodium concentration (hyponatremia), and inadequate pre-loading (i.e. entering exercise well hydrated) with fluid AND electrolytes, particularly sodium. Also, the widely available sport drinks didn’t work well with me – I have since read (at www.migraineweb.com) that MSG is used as a flavour enhancer (not good for headache sufferers or anyone else) in some sports drinks, but have yet to confirm this.

I have had better success with a sport drink product named “e-load”, developed by a Toronto Sports Medicine specialist, Dr. Doug Stoddard. I like the formula for its sodium content and its “anti-bonking” effects. Not to be understated, it has had a huge impact on my life and allowed me to perform better, more vigorously and with longer endurance, while negating all of the previous post-exertion adverse effects. Simply, it kept me in the game.

Let it be known that dehydration is the most common performance-sapping mistake that athletes make, but it’s also the most preventable. Here are some guidelines to help athletes stay well hydrated. Remember that everyone sweats differently (in sweat volume and sodium content – in fact I am likely a “high-salt sweater”) and therefore needs vary as to fluid and salt requirements before and during exercise. A general recommendation is 1 gram of sodium per hour of intense exercise.


Hydrate before exercise begins

Drink 2-3 cups (475-700 ml) of fluid 2-3 hours before exercise to allow excess fluid to be lost as urine. This may mean drinking the evening before for early AM exercisers. About one-half hour before exercise, drink 5-10 oz (150-300 ml). Use a sports drink with adequate sodium content, as indicated below.

Drink during exercise

Most athletes find it helpful to drink every 10 to 20 minutes during a workout. Heavy sweaters can benefit from drinking more often (e.g., every 10 minutes) and light sweaters should drink less often (every 20+ minutes).

Ingest sodium before and during exercise

Sodium lost in sweat must be replaced during exercise. That’s one reason why a good sports drink is better than plain water. Before a long endurance activity, increasing dietary salt 10 -25 grams for the few days prior is helpful.

Use weight as your guide

The best way to determine if you’d had enough to drink during a workout is to check to see how much weight you’ve lost. Minimal weight loss means that you’ve done a good job staying hydrated. Remember that weight loss during an exercise session is water loss, not fat loss, and must be replaced.


Don’t rely solely on water

For the athlete, drinking large amounts of water is not only unnecessary, but can be downright dangerous. Drinking water alone keeps you from replacing the electrolytes lost in sweat (and from ingesting performance-boosting carbohydrates that help you train longer and stronger). Bloated stomach, swollen fingers and ankles, a bad headache, and confusion are warning signs of hyponatremia, a harmful electrolyte disturbance that can occur due to excessive water intake.

Don’t gain weight during exercise

A sure sign of too much fluid intake is weight gain during exercise. If you weigh more after your activity than you did before, that means that you drank more than you needed. Be sure to cut back for the next time.

Don’t restrict salt in your diet

Ample salt (sodium chloride) in the diet is essential to replace the salt lost in sweat. Because athletes sweat a lot, their need for salt is much greater than for non-athletes. During non-activity (or for the sedentary), I recommend a teaspoon of sea salt for every 2 litres of purified water – consumed daily.

Don’t use aspirin, ibuprofen and other non-steroid anti-inflammatories
These medications increase the risk of hyponatremia in athletes, and should be avoided.


Drink adequate amounts of fluid designed for exercise, and enter your activity well hydrated while finding a drinking routine that suits your individual needs. (On the day of a hockey game, I’ll drink 3.5 litres of sport drink – totalling the before, during and after fluid consumption.)

Disclaimer: The information contained in this article is for educational purposes only. One should always seek the personalized advice from a qualified practitioner before making the dietary and behaviour changes listed, as the needs and medical status of individuals are highly variable.

Dr. John Gannage, as a licensed physician, practices Functional and Integrative Medicine in Markham, Ontario, serving the Greater Toronto Area and beyond. He earned his Medical Degree from the University of Toronto. He recommends therapeutic lifestyle programs and various detoxification strategies to assist in the management of chronic health problems. His services include nutrition counseling, vitamin infusions and chelation therapy.