Training in the heat is one of the toughest challenges an athlete can face and it can have a significant impact on your race day experience. When I laid out my schedule for the year, I knew I’d have to hit a full heat acclimation protocol ahead of Ironman Texas and carry that on through the summer 70.3 block I intend on racing. I’ve done a number of heat acclimation blocks throughout my career, but with the addition of the hDrop Gen 2 device into my training tool box, I was able to be much more analytical this year when compared to previous years.
When your body adapts to high temperatures—a process known as heat acclimation—it undergoes a number of physiological changes that lower cardiovascular stress and boost endurance. Historically, tracking these biological shifts required an expensive sports science laboratory, complex mathematical equations, and single-use sweat patches. However, real-time hydration monitoring that hDrop provides has revolutionized this training phase. The hDrop Gen 2 Wearable Hydration Sensor serves as a reusable biosensor that provides continuous data directly to your phone or Garmin device. During my heat acclimation phase, I focused on three critical sweat biomarkers—the onset of sweating, total sweat volume, and electrolyte concentration. I also paid attention to skin temperature changes throughout each workout and sauna session. With this data, athletes can use hDrop tech to precisely quantify their heat acclimation progress and build an optimized, data-driven hydration strategy (more on the hydration strategy in future blogs!).
Onset of Sweating: Your Body’s Early-Warning Cooling System
When you first start training in the heat, your body hasn’t learned (or doesn’t remember) how to efficiently cool itself down. It waits until your core temperature is already elevated before it finally turns on the faucet. This can result in you feeling sluggish and overheated early in your workout. But as you acclimate, your brain’s internal thermostat gets a major upgrade. It adapts by triggering your sweat glands much earlier and at a significantly lower body temperature. The hDrop wearable catches this shift in real time by spotting the exact minute your skin’s moisture levels spike. Evaporation is the most efficient means the body has in dissipating heat. The earlier you begin to sweat the earlier you can start preventing the core temp from rising. When your body gets to the point where you begin sweating almost as soon as you start your session, you have your first sign that your heat acclimation is progressing!
Total Sweat Volume: Upgrading Your Internal Air Conditioner
Think of heat acclimation as swapping out a weak, old air conditioner for a high-powered industrial cooling system. Over a couple of weeks of heat exposure, your sweat glands actually grow larger and become much more active, allowing them to pump out a lot more fluid per hour. If you aren’t used to the heat, your body simply can’t sweat fast enough to match the environment, causing your internal temperature to go up too quickly. Because the hDrop sensor keeps a continuous eye on your fluid loss, you can watch your hourly sweat rate steadily climb as you adapt. This massive boost in sweat volume ensures your skin stays covered in moisture, maximizing your body’s ability to shed heat into the air and keeping your performance higher when the weather gets brutal. Another adaptation to the heat protocol is an increase in blood plasma volume. This increases your stroke volume (and therefore your VO2 Max!) as well as gives you more of a reserve to handle the additional sweat volumes. Just a 2% drop in your hydration status can result in up to a 10% reduction in your over performance, so this adaption is extremely important!
Electrolyte Concentration: Becoming a Highly Efficient Machine
In the first few days of heat training, your sweat is incredibly salty, meaning you are draining your body of essential minerals like sodium and chloride. This heavy mineral loss will lead to excessive fatigue both acutely in your current session as well as in your workouts in the following days. Luckily, another important adaptation your body makes is learning how to conserve these nutrients. As you get used to the heat, you start recycling sodium back into your bloodstream before it can escape through your pores. By tracking the changing electrical conductivity of your sweat, the hDrop app lets you watch your sodium-loss numbers drop day by day. Your sweat becomes much more diluted and efficient, which keeps your blood chemistry balanced and means you won’t have to choke down nearly as many salt pills just to survive your workout.
Reading the Signals on Your Dashboard
Here are some of the things to look for when using your hDrop to assess your progress in your head acclimation phase of training. You will know your body has experienced significant adaptations when the numbers on your screen stop changing and hit a flat line when comparing sessions with similar conditions. Here is exactly what that looks like on your hDrop dashboard (note that the recently launched hDrop Lab will do a lot of the heaving lifting for you!!):
- The Sweat Timer Freezes: In the beginning, it takes longer to start sweating. As you adapt, that “time to first sweat drop” moves earlier and earlier until it finally locks into place. If your app shows you are continually breaking a sweat very early on in a session, you can be comfortable in knowing you’ve experienced a fair amount of the desired adaptation.
- Your Sweat Volume Hits a Ceiling: Your hourly fluid loss will climb drastically over the first week as your internal air conditioner ramps up. Eventually, that number will stop climbing and level off. When your sweat rate hits a steady peak and stays there, your body has maximized its cooling capacity.
- Your Sodium Loss Bottoms Out: Your first few days may show scary-high numbers for sodium loss, especially if your beginning fitness levels are on the lower end. But as your sweat glands ‘get smart’ and start recycling those minerals, that sodium graph will plummet. Once that downward trend flattens out and your hourly salt loss hits a consistent, low number, your body has officially become a mineral-saving machine.
Once those three charts stop moving and look identical for two or three workouts in a row, you have officially crossed the finish line of heat acclimation. It’s important to remember that the work doesn’t stop there, however. Once you’ve hit your desired adaptations, you need to keep the heat stress in your normal routine to maintain those changes. In the past, I’ve targeted 14 heat stress sessions in a 21 day period during the active heat acclimation phase and then 1-2 sessions per week while in the maintenance phase. While using the hDrop, I was able to see quantifiable proof that the 21 day protocol was sufficient to reach the desired outcome. I’m looking forward to (hopefully) confirming that the 1-2 sessions per week is enough to maintain those adaptations as we hit the summer months.
If you’d like to learn more about hDrop Technologies, make sure you check them out HERE. You can use code MATTHANSON10 to save 10% on your order as well!
