Exercise, Hydration and the Dog Days of Summer

Think of Your Heart chronicles by , July 2, 2012 - 15:15

Meteorologists are forecasting a scorching day, with temperatures reaching 32 degrees C, in the shade.  You had planned on going cycling?  What to do?

During intense efforts, the body becomes a real furnace.  In hot weather, our thermoregulation system is strongly put to the test.  In addition, when there is a high level of humidity in the air, sweat evaporation is reduced and there is a high risk of overheating.   In reality, our body needs to get rid of the heat generated by the muscles in order to maintain an adequate temperature (thermoregulation mechanism).  

Plan your training in accordance with the weather: 

  • Do your training, if possible, in an air-conditioned room.
  • Split your training session into two 15-minute periods.  Take advantage of the morning coolness and complete your training with a walk after supper!  You will enjoy the same health benefits as if you had exercised continuously for 30 minutes! 
  • Above all, do not forget to take plenty of liquid.

In hot weather, our thermoregulation system is strongly put to the test. 
Plan your training!

What to drik and when to drink?



Quantity to drink


2 hours before

500 ml of liquid


10-15 minutes before  

125-250 ml of liquid


Every 15 minutes 

125-250 ml of liquid


After effort 

1.5 litre of water per kg of lost weight

What to drink?

Temperature during effort 

Exercise duration

Type of drink

Hot and humid 

< 1 hour 

Water (except if you haven't eat for 4 hours or more)


> 1 hour 

Water + glucides + electrolytes (Sport's drink, see recipe)

Cool or cold

< 1 hour 



> 1 hour

Water + glucides


With the cooperation of Élise Latour, Nutritionist

The Montreal Heart Institute is in no way responsible for the following comments. These comments reflect the views and opinions of the users and not those of the Montreal Heart Institute.

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