by Terri Rejimbal, RRCA Coach

Hooray! Summer is here! Less bulky clothes, longer daylight hours, and runner tan lines! Can you hear my enthusiasm?

It’s also that time when the Fahrenheit rises and running paces plummet. Let’s face it, running in warm temps is hard enough, and when you add in higher dew point, temperatures feel even warmer, breathing is more rapid, and it’s more challenging to cool your body. If you’re like me, I tend to get discouraged and frustrated when I am not hitting the race times or splits like I was just a few months earlier.

In Florida, there are at least another 4 months of high heat and humidity that I can’t escape, unless I run on a treadmill, which I don’t wish to do!

Although there is no ideal time to run during the hot summer months, early morning before dawn is usually the coolest time of the day, but it’s most humid. Running in the evening, after sunset is less humid, but the temperature is higher. Times to avoid are between noon and 3:00pm.

Sounds like there is no escape? There is! The key is to work with the heat rather than trying to beat it. Use the tips below to defend yourself against summer’s heat and humidity, while maintaining your confidence and motivation as you train for your fall marathon.

Dress Cool. Clothing should be loose, light in color, and made of lightweight technical fabric with venting or mesh to allow air to circulate and evaporate. I find wearing a hat or visor, sunglasses, and a 30-SPF or higher sunscreen gives me the feeling that I have some protection from suns rays, and perhaps the heat won’t hit me as quickly as I am creating my little space of “shade” from the sun.

Drink Up. Lower your core temperature before hitting the road with an icy slushy. Research has shown that runners who slurped an icy slushy before a hot run lasted 10 minutes longer than those who just drank a cold beverage. Drink according to thirst and have a hydration plan so that you avoid drinking too little or too much (hyponatremia).

Know your Sweat Rate. The best way to gauge how much fluid you need per hour of running is to take the sweat rate test. Simply, weigh yourself (nude) before and after a one-hour run. Take your pre-run weight minus post-run weight, convert to ounces, add any fluid ounces consumed during run. This equals your individual hourly sweat loss.

To determine how much you should drink every 15 minutes during your next run, divide the hourly fluid loss by 4. Using the example below, you should consume 10 ounces every 15 minutes.

Ex: 130 lbs/pre minus 128 lbs/post = 2 lbs. or 32 ounces Add 8 ounces consumed during = 40 ounces/hour
40 ounces/hour divided by 4 = 10 ounces/every 15 minutes

Because sweat loss varies with your pace and current day environmental conditions such as temperature, humidity, altitude, etc., you should retest on another day when conditions are different to see how your sweat rate is affected.

Direction. You may not be able to control the course on race day, but you can control daily routes! When you can, pick shade. If you can run a loop, leave a cooler in one spot with cold fluids, ice cubes, a dry towel and circle back to them. If there is a breeze, run out with wind at your back and return with in your face. It will help keep you cooler.

Cool Off First. Lower your core temperature by cooling down before the run with a cool shower, jump in a pool, or carry a towel or sponge to squeeze water onto your skin.

Here are some tricks I used before two very warm marathons:
The night before the Jamaica marathon, I lowered the air conditioner thermostat and slept in a cold environment. This made my body feel colder than the outside temperature. When the race started at 5:15AM, the outside temperature of 77-degrees felt nice and extended the time before I started to over-heat.

During the Kona marathon, I carried ice cubes in a zip-lock bag. I learned this idea from a Stanford study that looked at overheating and fatigue in athletes. Researchers hooked athletes up to a “cooling mitt” which ran cold water along the palm of the hand, the body’s primary heat radiator. The study concluded that by circulating cold water through the mitt, athletes were able to reset the muscle’s state of fatigue and reduce the athlete’s core temperature.

Dew Point. Temperature, Humidity, & Dew Point – what does it all mean? Temperature refers to how hot or cold outside air is. Relative humidity (RH) indicates the amount of moisture the air can hold relative to the temperature. When RH is 100% the dew point and the temperature are the same. Warmer air holds more water vapor, thus giving that muggy, sticky feeling. Humidity refers to degree of dryness/wetness in the air and is figured as a percentage. Dew point is the temperature at which dew droplets form. So when the temperature is 75 and the dew point is 75, you will see dew or fog appear. As the dew point creeps up closer to the actual temperature, there is more water vapor is in the air, and it’s harder for sweat to evaporate and keep you cool. It’s undoubtedly going to be an oppressive run so scale back on your pace. Use the charts below to help guide your training paces over the next few months.


Instead of avoiding heat during training, train your body to adapt to it. Start by acclimating to the heat by doing a minimum 5-10 runs of an hour or more at reduced exercise intensity for the first few days. After several days, you’ll begin to see signs of heat adaptation – better control of body temperature; sweat sooner through increased sweat gland activation; slower transit time of sweat; thus reabsorbing electrolytes; blood plasma volume increases which sends blood to your skin to help keep you cool without compromising the blood supply delivering oxygen to working muscles; lower rate of glycogen depletion; and lesser heart rate increase than one not heat adapted.

You also won’t need a lengthy warm up before starting your track, tempo or race because your body has become more efficient at heating and cooling, thus sparing glycogen stores for later demand in the workout or race.

Summer is here, but don’t let it squash your fall marathon plans! By being smart, keeping your cool, and running conservatively, you’ll be ready for any temperature. And if your fall marathon happens to have cooler weather than you’ve trained in, embrace it and enjoy the race!

Terri Rejimbal is a competitive Masters athlete, 3-time Gasparilla Distance Classic half-marathon winner, 6-time Disney Masters marathon winner, and a New Balance product tester. Terri is a RRCA run coach, CPR/AED certified, and is available for consulting or coaching services. For more information, contact Terri at