Research is the process of solving problems and finding facts in an organised way. Our research started back in the mid nineties, with the sole purpose of providing a healthier and safer hydration strategy for fire fighters on the fire ground.
This has lead to over 1500 tests gathering information on volume of sweat and the electrolyte composition of sweat to determine the critical components necessary to providing a healthy and safe hydration strategy.
The Pie Graph below shows the electrolyte composition of sweat for sodium, potassium and magnesium. Sweat was collected from 16 participants who cycled indoors for one hour at 80% max/heart rate. The samples were sent to the Australian Institute of Sport where they were analysed. Each electrolyte is measured in milligrams per one-litre of sweat.
There is a clear contrast between the amount of sodium lost in sweat when compared to the amount of potassium and magnesium. The reason for this is that each electrolyte has their own characteristic and in the case of sodium it is extracellular, which means it is mostly present in the bloodstream. As for potassium and magnesium they are both intracellular, meaning they are mostly present inside the cell.
While all three electrolytes have very important roles to play in how our body functions, the main electrolyte to replace when experiencing sweat loss is sodium, simply because we lose a lot more of it.
ELECTROLYTE CONCENTRATION IN SWEAT
The concentration of electrolytes sodium, potassium and magnesium in sweat of 16 subjects. They cycled at 80% max / HR for one hour in 22 degrees and 45% humidity. The results of this test show the disparity between electrolytes lost in sweat. The concentration of electrolytes lost in sweat is measured in milligrams per one-litre of sweat. In this test the electrolyte composition per one-litre of sweat averaged out at - sodium 1061 mg. - potassium 195 mg - magnesium 3 mg.
SODIUM CONCENTRATION & ACCUMULATIVE SODIUM LOSS IN RAIL WORKERS
The graph below shows the sodium concentration of sweat and the accumulative loss of sodium from 22 rail workers who were tested while performing light duties for a duration between 44 - 49 minutes in temperatures ranging between 28 - 31 degrees and 77 - 83% humidity. Radiant heat from the ground was recorded between 38 - 42 degrees.
The orange bars show the sodium concentration of sweat for each rail worker, which is measured in milligrams per litre of sweat. The purple bars show how much sodium was lost in total when the sodium concentration and the rail workers sweat loss was multiplied. For example 1.6 litres X 891 mg = 1425 mg of sodium lost.
The purple and orange bars show how varied the sodium concentration and total sodium lost is between the 22 rail workers. Some people simply lose more sodium than others and some will lose a lot more than others, which we have seen consistently in all the sweat testing we have performed over the years. In fact there are some workers who will naturally perform and tolerate working in hot environments better than others. These workers will have a lower sweat rate (volume of sweat they lose is less) and they will have a lower sodium concentration in their sweat. What this means is that they are able to manage their losses more effectively than those workers who have a higher sweat rate and a higher sodium concentration in their sweat.
If there are workers who are susceptible to working in hot environments that suffer heat related illnesses more often than others, it is simply identifying their unique physiological makeup and addressing their needs accordingly. More often than not, increasing the volume of fluid and the amount of sodium in that fluid when experiencing sweat loss solves the problem. By doing this the worker is addressing their individual needs more appropriately, which in turns minimises their blood volume and sodium loss through sweating.
Workers are supplied different sized PPE - gloves, boots, clothing etc. to address their unique characteristics so they are comfortable when working. The volume of sweat they lose and the amount of sodium that is present in that sweat is unique to the worker as well and we know just how to ensure every worker is covered when it comes to working in hot environments.
The sodium concentration and accumulative sodium loss of 22 rail workers working for 44 - 49 mins in temperatures between 28 - 31 degrees, all performing light duties
SWEAT RATE FOR RAIL WORKERS
The bar graph below shows the volume of sweat that was lost by 22 rail workers performing light duties for 44 - 49 minutes in temperatures between 28 and 31 degrees and 77 - 83% humidity.
Sweat rate is the volume of sweat that is lost during a certain duration. A pre weight measurement is collected prior to the test and a post weight measurement is collected after the test. The difference between the pre and post weights is an approximation of how much sweat has been lost. This sweat loss is a direct correlation of blood volume loss due to our blood being 80% water.
The results show no trend in sweat rate, even though the 22 rail workers were performing similar light duties, wearing the same personal protective equipment working in similar environmental conditions. This is reflective of the results we have seen from testing over 1500 people.
The message here is that in certain conditions some workers will need to consume a greater amount of fluid compared to others, simply due to the greater volume of sweat they are losing. Just this small amount of information can trigger a response in the worker to be more conscious of monitoring their individual needs when it comes to hydrating properly.