It’s marathon training season, especially here in NYC, as we are just 12 weeks out from the New York City Marathon! One of the unavoidable downfalls of training for a fall marathon is having to run through the heat and humidity of the summer. For every 10 degree increase in air temperature above 55 degrees, there is a 1.5-3% increase in average finish time for a marathon.

NYC Background

The higher the heat rises, the harder it is for your body to keep itself cool. The muscles fight with the skin for blood; muscles need blood to function, and skin needs blood to cool the body. When oxygen is redirected to your skin instead of your muscles, you have less energy for running and your heart and lungs have to work harder which can cause an inability to maintain the same running pace that you are able to on a cooler day.

Sweating and the evaporation of sweat allows the body to cool, however when humidity is high, the rate of evaporation decreases and cooling is slowed.

Although sweating is the body’s mechanism for cooling, it can also lead to significant dehydration. A loss of too much water (>2% of body weight) can have significant effects on performance- up to a 6% drop! In addition, as temperature and humidity increase, heart rate increases and perceived effort is much greater.

Unfortunately we cannot “beat” the heat, but we can teach our bodies to be more efficient in it! Running in hot conditions results in changes that make it easy for our bodies to handle exertion in the heat. These physiological changes include higher blood plasma
volume, increased sweat rate, decrease electrolytes in seat, and a quicker onset of sweating.

Here are some tips to keep you safe during your long (and short!) runs this summer:

  1. Be aware of the time of day that you run. Early in the morning before sunset, or in the evening after sunset will be the coolest times. Avoid the hours of 10am-4pm which are often the hottest part of the day.
  2.  If you can’t run before sunrise or after sunset, do a portion of your long run, or a speed workout on an indoor track or a treadmill in an air-conditioned gym.
  3.  Stay hydrated! Make sure to carry water or a sports drink with you during your run and consume 16 oz of water about an hour before the run. Freezing a water bottle before your run will help keep the water cool for longer durations!
  4. Beware of other dehydrating actions. Avoid alcohol, caffeine, and ibuprofen before and after your run, as these can increase dehydration and electrolyte imbalances.
  5. Avoid cotton which holds in heat- wear light colored synthetic fabrics to wick away the sweat.
  6. Use waterproof sunscreen with SPF 30+ to all exposed skin
  7. Decrease the intensity of your workouts in order to decrease risk of heat related disease. Consider adding a 1-2 minute walking break every mile. This will prevent your heart rate and body temperature from rising high.
  8.  Know the signs of heat related illness – increased heart rate, dizziness, nausea, unable to catch your breath, extreme thirst, lack of sweating. If you experience these symptoms call 911 immediately.

Runners Sneakers

Remember- hot days are not the time to try to PR. Stay hydrated and take plenty of breaks to stay safe! Happy running!