It's heating up fast in some parts of the country and I know you are all ready to go crush some miles and workouts but since I just finished a continuing education class in heat acclimatization for my Certified Strength and Conditioning Specialist certification, I figure I'd share some information to help you all adjust to the heat.
Exercising in the heat when you are not used to it can put you at a higher risk of heat-related illnesses (heat exhaustion, heat stroke and cramps - please google these terms and be familiar with the symptoms). As you acclimate to the heat, you will lower that risk and your body will become better at regulating your heart rate and body temperature in the heat, your comfort level will improve and your exercise capacity will improve. You will become better at sweating (sweating more and earlier into your workout), you will retain more electrolytes and your natural thirst will better match your water needs.
Acclimatization is a process where you repeatedly expose yourself to heat in such a way to produce profuse sweating and elevation of your body temperature. The process of acclimatization takes about 2 weeks. Here's how to do it:
1. SLOWLY work up to being able to exercise at a level that produces significant sweating for 90 minutes in the heat.
2. Once you can do that, exercise for 90 minutes in the heat (or two times a day for about an hour each) for the next 7-14 days.
3. MAKE SURE TO TAKE IN ADEQUATE ELECTROLYTES AS YOU DO THIS. You can sweat out as much as 6 times as much of your electrolytes when you are not acclimated to the heat!
4. If you don't have time to exercise this much in the heat each day, it may take longer to acclimate. Simply spending time in the heat can help with acclimatization but resting in the heat won't do it as quickly as exercising in the heat. Also, sleeping in the AC or spending time in cool environments won't negatively impact your acclimatization efforts and could be good for recovery.
5. With better acclimatization to the heat comes more sweating. If you notice you are sweating more or more easily, that's a good sign but remember that as you become better at sweating, you need to drink EVEN MORE WATER and you should still put electrolytes (like NUUN tabs or equivalent) in your water.
6. Know that the jury is still out on whether being acclimated to dry heat transfers fully to being acclimated in humid heat and vice versa so if you go somewhere with a different warm climate than you are used to, you may have to scale things back a bit.
7. You start losing your acclimatization after about a week and can lose about 75% of it after 3 weeks of not exposing yourself to heat so if this happens, you may have to ramp up again but you will become acclimated again faster if too much time has not passed.
Reference: Gatorade Sports Science Institute's Heat Acclimatization to Improve Athletic Performance in Warm-Hot Environments Course