Sweat analysis data - the innovation that can prevent ruining our performance.

We all do it. We all talk about drinking enough water in the day. But is this the full story of dehydration and what do we lose in our sweat? This is my story of using FLOWBIO’s S1 to discover my hydration analysis data to become a better me.

Sweating is dependent on the individual, whether you are a cyclist, a runner or any active person, we all sweat differently, but it can ruin our performance all the same.

Sweat is something that occurs naturally and what it contains depends on what glands it comes from. Our body is covered in glands but the main two we are focussing on for sweating are the Eccrine glands and Apocrine glands.

Eccrine glands produce most of your sweat and it is the salty type of sweat you get. This is the sweat that you will see on your cycling jersey after a hot event. The watery sweat from these glands also contains bits of salt, protein, urea and ammonia. These are commonly found on the palms of the hands, the armpits and the forehead, but do cover the entire body.

Apocrine glands are much larger and are found near the hair follicles, so the groin, the armpit and the chest area. Being close to the hairs on our body, they are the sweat glands that come with an odour, and this is what we know as BO.

Drinking water is something we are told during our childhoods to be more hydrated, but unfortunately, it is not that simple. In sweat, we lose sodium, and this can become imbalanced which causes a loss in performance but it can also affect us day to day. Some of the key signs of dehydration are:

• feeling thirsty.

• dark yellow, strong-smelling pee.

• peeing less often than usual.

• feeling dizzy or lightheaded.

• feeling tired.

• a dry mouth, lips and tongue.

• sunken eyes.

• headaches, feeling sick or the feeling of being hungover

But as a cyclist, or any performing athlete, dehydration can not only cause physiological effects but also affect our psychological performance.

The main reasons dehydration has an adverse effect on exercise performance can be summarized as follows:

• Reduction in blood volume

• Decreased skin blood flow

• Decreased sweat rate

• Decreased heat dissipation

• Increased core temperature

• Increased rate of muscle glycogen use.

I was lucky enough to meet Stefan Van Der Fluit and Hattie Freeman from FLOWBIO for a podcast recording and a delve into the science and technology behind the S1 and how we can monitor, analyse and come up with a hydration plan based on our sweat.

The full podcast can be found here: Deleting dehydration with FLOWBIO

Once this podcast recording was finished, I got my hands on the S1 to test out. I had one burning question, “does our sodium concentration change depending on the workout intensity, and if so how much?” So I used the S1 for a training week during early winter to hopefully answer this question. From zone 2 rides indoors and outdoors to vo2 intervals, I was surprised by the results, the first big one was that I was dehydrated and in a sodium deficit on the first zone 2 easy ride, which was worrying as this means I have never been drinking enough and having enough electrolytes.

As the screenshot above shows, there was a difference of 642mg of total sodium loss between the highest and lowest in the training data. I must say that these were not performed in a lab environment, but they were all an hour in duration, all in the same location and on the same equipment. The zone 2 ride on the 17th of November was a heated session, which I have been implementing this winter ahead of some 2025 goals, leading to more sweat and a higher sodium loss. This however is not a reason to ignore the result, as this is part of my training, and it shows that we must be aware of what we are doing and what we are replenishing or losing in our sweat.

Regarding sports products, the difference between my training week was just over 1x STYRKR SLT07 500 tab. However, during these sessions, I had what I always have had in my bottles, a 500mg tab. So, before I even think about how much my sodium varies between sessions, I am already in a deficit of 500mg-1000mg, and that is before I even start. So in one bottle instead of having 1x 500mg tab, I should have at least been having 1x 500mg bottle and 1x 1000mg bottle per hour session, if not more.

As I said earlier, I always assumed my hydration was spot on, as I have been with nutrition, but this goes to show that “guesswork” is not a valid base to use. I didn’t always feel the symptoms of dehydration, I didn’t finish a ride with headaches or post-ride fatigue. But moving forward, and ensuring I have been using more electrolytes, the performance and how I feel on the bike have drastically improved.

Hindsight is a funny thing, you never know what you are missing, until you find it or experience it. Power numbers are not up much because of hydrating better, but how I feel is completely different, especially on the longer endurance rides. With longer sustained efforts, on the flat and climbs, I can ride out the saddle for longer without the quads or hamstrings tightening up (just before cramping), I can regulate my heat a lot better, meaning that I can sustain a higher power without burning up and helping to keep my core body temperature down, allowing repeated efforts.

Full video and results can be found here: Does sodium concentration vary within a training week?

Here at AKCCoaching and CORE Bike Fit, we are stoked to announce that we are one of the first FLOWBIO AHi Affiliated Lab. Using the S1, along with CORE body temperature sensors, we offer sweat “testing”, with everything you need to get your personal hydration plan.

After a short consultation, we have you on the bike, using the S1, for a 60-120 minute zone 2 base ride, using Wahoo equipment. The longer the session the better the data you can walk home with. Post-workout, you have a chance to browse some STYRKR products and wander around the shop, before we go through your data and recommend products for you to use, to match the sodium concentration for your effort.

But your video showed that it isn’t ‘one number does all’ when it comes to hydration!

Yes, this is true, but for someone who has no idea what their sodium concentration is, this is a great method to get a baseline and for longer but easier rides it is an idea of what your body demands. Using the CORE sensor we can also see what your body is doing, so if you know you are doing a 60-120 minute ride in hotter or cooler conditions you can adapt your hydration accordingly.

But as with any technology, how you use it can be a game-changer. The ability to get real-life data on your sweat is a great way to prepare for events or races, for example, I will be using this going into my TT season. I will be wearing the S1 during a mock TT effort indoors to replicate a race scenario to see how I need to change my hydration for these types of races, this will also be backed up and updated during the race season to see how I may need to change my hydration from race to race.

Sweat is something we all do, it is something that we can now easily analyse and track our data. Thanks to the guys at FLOWBIO, this is something become more accessible to us as coaches to educate our clients and to help people get stronger through hydration and not just nutrition and training. But also it allows cyclists to learn for themselves, test their limits and improve their cycling, as the S1 is available to purchase from FLOWBIO or a AHi Affiliated Lab like us at CORE Bike Fit.

Get in touch if you have any questions about our sweat testing, how to book or just some information on hydration and how you may be feeling the effects of dehydration - because I can be fairly sure you are under-hydrating.