I always run with hydration and fuel in my Naked running belt (all year long) but no surprise - I go through my fluids much quicker when it's hot and steamy outside.
Although it can be misearble (and sometimes dangerous) to train in the heat, there are a few ways to help mitigate the physiological response to exercising in hot and humid temps.
First off, it's important to understand why exercise feels so difficult in the heat.
- Blood that would normally go to the working muscles in a cooler environment is now going to the skin for cooling (so heat can be released into the air).
- Your body is trying to maintain a safe body temperature (homeostasis). If body temp increases beyond a safe level, normal bodily functions can't be maintained and your body will shut/slow down.
- With a greater risk for dehydration and loss of electrolytes in the heat, your body can not maintain normal physiological functions. With less fluid in the body, your heart has to work even harder to keep blood volume up to function. In other words, when blood volume drops due to dehydration, your heart has to beat faster to circulate the same amount of blood through the body. When you are dehydrated and blood volume drops, it's incredibly difficult to meet all of the demands of the working body. Ultimately, the body will prioritize cooling and cardiovascular safety and you'll be forced to decrease your effort. If you try to fight it, you'll end up overheating and may fall victim to a heat-related illness.
- Do not attempt a run workout in the hottest hours of the day. Run early morning or in the evening when the sun is not blazing over you. Don't try to be a hero - if it's not safe outside, take your workout indoors (ex. brick running).
- Wear appropriate clothing that keeps you cool, comfortable and protected- lightweight, loose-fitting, breathable and sweat wicking. Don't forget to use sunscreen, wear a breathable hat (and sunglasses) and utilize a cooling towel around your neck. Plan your route to include shade, water fountains, gas stations (for refilling) and off any new asphalt.
- Don't ration your fluids - stop and refill before you run out of fluids. Aim for at least 10 ounce fluid, 80-100 calories and 240-400mg of sodium per every 30-45 minutes of running. Sip every 8-15 minutes. Use plain water for cooling the body.
- Adjusting to the heat takes time. It needs to be taken with caution. Keep an eye on your heart rate - even if your pace feels "slow" your rising heart rate will remind you that your body is perceiving the effort as "hard."
- Adjust your effort during structured workouts. Think of intervals as progressive - try to get stronger as the workout continues. Start out easier to reduce the chance of overheating. Starting out too hard (ex. in an interval or in the early part of a workout) will inhibit the body from being able to cool itself.
- Speed intervals, tempo work and race efforts require adjusted expectations in hot conditions (the best strategy is to not have expectations or a set outcome goal). You will likely need to give yourself more rest to lower the heart rate between intervals or incorporate more walking between intervals. Because the heart rate will rise quickly in the heat and will continue to rise (cardiac drift), your intense efforts should not be forced. It won't take much to increase your heart rate to a "strong" effort.
- Don't be tempted to keep the pace of a training partner. Listen to your body cues to prevent overheating. Focus on your fueling/hydration needs - drink when you need to drink and stop when you need to stop.
- Focus on your hydration and fueling in the 72 hours before and after the workout. Preparing for a hot weather workout does not mean only focusing on what you eat/drink in the hours before and after the workout. Because of the taxing nature of hot workouts, you need to prepare in advance and plan well after the workout is complete.
- Monitor the signs and symptoms of a heat related illness. Chills, headache, nausea, dizziness, no urge to urinate, dark urine, confusion and light-headedness during and after a workout are not normal and should be taken seriously.