If you live in the northern hemisphere, you're inching closer to summer and hopefully your weather is warming up nicely! You may have noticed that your body performs differently in warm/hot weather conditions.  Many athletes note a drop in performance when they are first exposed to heat in training. Have no fear, this is expected and we can plan for it. Below, I describe three key strategies for heat acclimation. Follow these and you will find you perform well in the heat and even look forward to warmer weather race conditions!

1. Exposure and acclimation

For athletes to perform well in hot conditions, they will first need a period of exposure and adaptation.

Patience: It takes approximately 14 days for the body to adapt to performing in the heat so adjust your expectations for your performance during that window. If you have primarily been training indoors or during cool morning hours, you will need to adjust your training schedule to expose yourself gradually and consistently to hot conditions before resuming a normal training schedule outdoors. Important to keep in mind: if you are training for a warm weather race during the fall or winter months, your heat acclimation will only last a week or so. You will need to repeat a heat training protocol close to the time of your race to maintain appropriate heat acclimation for race conditions.

Strategy: Your first few workouts in hot conditions should be short, easy effort, and end before you feel exhausted. After several short workouts in the heat, you can begin to increase the time (heat exposure) of your workouts until you can comfortably handle 60-90 minutes.

Plan ahead: Adjust your training schedule to decrease your total outdoors workout volume for your first 14 days while increasing perhaps your swims or indoor trainer workouts if total load is to be maintained.

2. Hydration

It goes without saying that proper hydration is key to handling training and racing in hot conditions. You may be wondering how much is enough and how you should hydrate?

Test, Don’t Guess: To understand your body’s unique fluid and sodium needs, you will need to perform a sweat trial (preferably 4-6 times to get an average) in the conditions you intend to race/perform under. If you know your race will be 85-90 degrees, perform your sweat trial when it is 85-90 degrees. This will give you the most accurate reading of how much fluid and sodium you lose under those conditions.

Replenish: It is not always possible to replace all of the fluid you lose during an athletic event but you can limit the negative effects of mild dehydration by replacing fluids up to 32+ oz. per hour. Some athletes can tolerate more than 32oz. per hour - this requires practice and training so plan ahead if you are signed up for a warm weather race. If you are losing more than 32 oz. per hour, you are likely losing a significant amount of sodium also. Aim to replenish 800-1500mg sodium per hour if you are a heavy sweater and have salt stains on your clothing after workouts.

3. Nutrition

We cannot understate the importance of nutrition (and hydration) in handling the effects of heat on the body. Your caloric intake needs to be sufficient to sustain your level of activity for the duration of training AND it needs to be absorbable by the gut.

Carbohydrate concentration: A general rule of thumb is to consume carbohydrates at a 6-8% solution, or ~25g carb/12oz. of fluid. This roughly translates to 3 gels per 36 oz. of fluid spread throughout an hour.

Train the gut: The key here is PRACTICE. This may feel like a lot of volume in your stomach when you first try out these numbers. Work up to it gradually over the course of a season. Your gut can adapt to the volume but must first be trained on smaller amounts and slowly increase amounts to see what works for you.

Absorption: Research and anecdotal evidence show that athletes can effectively absorb as much as 90g of carb per hour. You will only know by trial and error what your comfortable threshold for absorption is. Some athletes may choose to use liquid nutrition, that is, a carbohydrate replacement drink. A word of caution here: practice this strategy under “race-like” conditions to know how your gut will react. I recommend experimenting for NO LESS than 2 months with this strategy in the warmest summer weather before deciding if it will work for you. Liquid nutrition places a different type of stress on your GI tract as it is quickly swallowed and “floods” into the gut faster than a bolus of food. Keep this carefully in mind when choosing a nutrition strategy for hot weather races.

FINAL WORD:

Please do not hesitate to reach out and ask questions about adapting to the heat and fueling yourself to perform well in the hot summer months. Fueling for endurance and ultra endurance events is a long term commitment: you commit to experimenting with various strategies to assess how your body reacts and performs under race conditions.