Heat & Hydration

June 2024

Every day from June through September, Santa Rosa’s historical average high temperature exceeds 80º F. Let’s talk about cycling in the heat! 

I first learned about the concept of heat acclimation when a message popped up on my Garmin bike computer after a ride: “You are 12% acclimated to the heat.” According to Garmin, it takes up to four training days in the heat with a break of no more than 3 days to become fully acclimated. Turns out there is a whole body of literature about training for heat. This article provides an academic overview:

https://www.stmarys.ac.uk/blog/physiology/heat-acclimation-training.aspx 

The basic takeaway for heat acclimation is that your performance and comfort in the heat will improve as you repeatedly expose yourself to riding in the heat. Give yourself shorter rides of an hour or so each during warm afternoon weather over the course of a week or two, in anticipation of a longer days in the heat of summer. After reading a bunch of scientific articles with precise prescriptions, I uncovered the (fairly obvious) truth that people’s physiology relating to heat and acclimatization vary wildly. So please take the recommendations below and tailor them to serve you and your physiology. The goal here is maximizing your enjoyment, comfort, and performance in hotter weather. 

Research shows that being well hydrated has general health benefits. Getting dehydrated on the bike can result greater pain and the loss of endurance and power. On a long enough ride, dehydration may cause you to “bonk” with a substantial reduction in effectiveness. Once this happens, you can only limp home. Recovering from dehydration on a ride is pretty much not possible. Especially on a hot day, you cannot afford to get behind. 

Reaching 1% dehydration means that you have lost 1% of your body weight. A 150-lb rider would have lost 24 ounces of body weight. 2% dehydration is associated with significant reduction in performance and physical comfort. 

Be aware of the stages and symptoms of heat emergency: heat cramping, heat exhaustion and ultimately heat stroke and death. Dehydration leads to heat exhaustion with symptoms that include cramping, cool-clammy skin with goose bumps, heavy sweating, weak and rapid pulse, elevated temperature, head-ache, nausea, vomiting, dizziness, fatigue, weakness, anxiety, decreased urine output, confusion, fainting. Medical treatment should be sought if symptoms of heat exhaustion emerge and usually includes receiving intravenous fluids.

TRAINING PRESCRIPTION 1: HYDRATION PRE-LOADING

Routinely, get in the practice of drinking two to three cups of water after you rise in the morning. Then, take on another cup of water 20 minutes before the start of your ride. For longer rides, hydration pre-loading over the course of two days can be beneficial. One of SRCC’s champion riders habitually consumes several liters of water a day and his high level of hydration has make it possible to win double-century rides without getting behind the hydration curve. 

TRAINING PRESCRIPTION 2: TRY INFUSIONS

Though water is the key ingredient to hydration, the body does not absorb straight H2O very well. There are numerous products on the market, but if you’re out of your favorite product, do not fear! The hydration-boosting effect can be achieved with infusions of small amounts of substances in your kitchen cupboards. Adding just 1/16 to 1/8 teaspoon of salt per pint of water increases the absorption rate. Carbohydrate additives can also help absorption. For example, adding just a teaspoon of maple syrup per pint of water helps. Milk, tea, and fruit and herb-infused water are also ways to improve on straight H2O. 

TRAINING PRESCRIPTION 3: BRING A SCALE TO YOUR NEXT RIDE

Weigh yourself before the ride. Then, keep track of how much you drank during the ride. At the end of the ride, weigh yourself again to determine how much you need to be drinking to stay sufficiently hydrated. If you’ve lost weight, that’s a message that you need to be absorbing more. Naturally, this is most accurately performed with naked weighing, but the dryness of Sonoma County makes it fairly accurate weighing clothed.

RIDE LENGTH & HYDRATION

Up to 1 hour:  Hydrating before the ride reduces your need to worry about drinking during the ride. 

1-3 hours:  Drink on a schedule rather than to thirst.  A large bottle (24-28 oz) each hour with less than 1/4 teaspoon of salt added or another infusion.

Longer rides: Increase your hydration rate. Try drinking 16 ounces of strong electrolyte drink the night before the event. Then, drink one to two bottles an hour will help you keep hydrated. 

NOTE: There is a condition called hyponatremia where over-hydrating can result in improper electrolyte levels. Consuming too much plain water in pre-loading can cause this.  

I’ve added a few things to my wardrobe for hot-weather riding. Light-weight arm covers relieve me of the need for sunscreen and make it possible to squirt water on my arms for evaporative cooling. Levi’s Grand Fondo provided free “brow gutters” one year. These adhere to your forehead and direct your sweat away from your eyes (salt burning my eyes is one of my problems in the heat). This feature has been incorporated into the Head-Sweats do-rags. I like to keep one bottle with straight water to enable this kind of evaporation. I’ll alternate drinking out of my spiked water bottle and my plain water bottle and up the level of additive in the spiked bottle to compensate.

THE TAKE AWAY:

• Hydration improves performance
• A dash of salt or an infusion of ginger or watermelon will aid your absorption
• Drink a pint of water when you rise and a cup 20 minutes before a ride
• Take frequent sips during your ride; drink on a schedule. Don’t drink to thirst; if you’re thirsty, you are behind on hydration.
• Heat acclimation is possible and can be planned into your regime. 
• Body shape and characteristics such as % body fat, size, weight, and skin characteristics will all factor into above recommended quantities so that you have proper targets for your own hydration. 
• Refine your hot-weather cycling kit.

LINKS:

Bike Radar article: https://www.bikeradar.com/advice/fitness-and-training/cycling-in-hot-weather 

GCN video: https://youtube.com/watch?v=T9Ok_sSTJ50 

Training Peaks article: https://www.trainingpeaks.com/blog/how-to-avoid-hyper-hydration/ 

Paper on Inter-individual Variation https://www.sciencedirect.com/science/article/abs/pii/S0306456518300275

GCN How Salty is Your Sweat https://www.globalcyclingnetwork.com/brand/precision-fuel-and-hydration (promotes a company’s approach)