Bonking in the Texas Heat -Key Lessons for Triathletes
Pedaling a bike beneath the scorching Texas sun can be quite challenging. I'm in my 14th year living in the Long Star state and I learned this the hard way when I bonked during a recent training ride on a course that I ride regularly. This post shares my experience and the key lessons I learned to help you avoid bonking in the heat during your triathlon training or race.
What Happened on My Ride
I set out on my bike at 9:30 a.m., which I now realize was too late for a Texas summer day. (There was significant thunder and lightening at 6am so we missed our usual departure of 7:30am) The sun was already high, and the temperature was climbing fast. I didn’t start with my usual sodium tablets. Normally, I take one or two before leaving the house, but I forgot them this time. I also didn’t hydrate properly the day before, even though I knew it was going to be hot.
During the ride, I only drank about 18 ounces of fluids per hour. My sweat test showed I lose about 24 ounces per hour, so I was under-hydrating. As the heat intensified, I started feeling weak and dizzy by the second hour. At 2 hours and 30 minutes out, my legs started to cramp, and my energy plummeted. I can always tell when I am in a "bonk" when the back of my neck hurts and I feel dizzy when trying to hold my head up. Luckily I was close to home when I completely ran out of fuel and strength.
Why Timing Matters: Start Early to Beat the Heat
Starting a ride at 9:30 a.m. in Texas summer is risky. The sun is already intense, and temperatures can soar quickly. I learned that 7-7:30 a.m. is a much better time to start. The air is cooler, and the sun is lower, the earth is cooler, which helps reduce heat stress.
Early starts also give you more time to finish your ride before the hottest part of the day. (Notice that I bonked toward the end of the ride when the temperature was 10 degrees higher.) This simple change can make a big difference in your performance and safety.
The Importance of Pre-Hydration and Sodium Intake
As a rule, I usually take 1-2 sodium tablets before heading out in the heat. Sodium helps maintain electrolyte balance and prevents cramping and fatigue. Skipping them this time was a mistake.
Pre-hydrating the day before is just as important. When you know you’ll be training in the heat, drinking plenty of fluids and replenishing electrolytes the day before prepares your body to handle the stress better. Simply drinking one extra glass of water with each meal the days before can make a huge difference.
Following Your Sweat Test Protocol Is Crucial
A sweat test tells you how much fluid you lose during exercise. Mine showed I lose about 24 ounces per hour. But I only took in about 18 ounces during the ride. This mismatch meant I was quickly dehydrating, which contributed to my bonk.
To avoid this, follow your sweat test protocol closely. Drink enough fluids to replace what you lose. This keeps your energy levels stable and helps you perform better.
Signs You’re About to Bonk and How to Respond
Recognizing early signs of bonking can save you from a full energy crash. Watch for:
Feeling unusually tired or weak
Dizziness or lightheadedness
Heavy legs or muscle cramps (a key indicator of dehydration)
Difficulty concentrating
If you notice these signs, slow down, get in the shade, hydrate, and take in some electrolytes, quick carbs and some sodium. Don’t push through the discomfort—it can lead to a dangerous situation.
Practical Tips to Avoid Bonking in the Heat
Here are some steps to help you avoid bonking during hot weather rides:
Start early to avoid peak heat
Pre-hydrate the day before with water and electrolytes
Take sodium tablets before and during your ride (1 tablet is typically 100g sodium)
Follow your sweat test and drink enough fluids per hour
Wear breathable, light-colored clothing to reflect heat
Plan your route with shade or water stops if possible
Listen to your body and adjust pace as needed
What I’ll Do Differently Next Time
This experience taught me to respect the heat and prepare better. Next time, I will:
Start my ride at 7 a.m.
Take sodium tablets before leaving the house
Hydrate well the day(s) leading up to this effort
Stick to my sweat test hydration plan
Carry extra fluids and electrolytes on the bike
Remember, preparation is key to staying safe and strong under the Texas sun.
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