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#Sweat #testing

In earlier blogs we’ve mentioned what sodium is and the way it could be useful throughout train. We’ve additionally mentioned that the quantity of sodium misplaced in sweat varies considerably from individual to individual. On this article, we’ll check out methods to decide your sweat sodium losses, and key issues in case you select to do the testing.

Sweat testing methods

What’s a sweat sodium check?

A sweat sodium check is principally a means of accumulating a pattern of sweat after which analysing it to find out the sodium focus (what number of mmol or mg per L of sweat). There are a number of totally different testing strategies, and that is vital as a result of some assessments, and even the way in which the check was carried out, will affect how properly the pattern collected displays the sweat losses that can occur in an actual coaching or competitors situation.

Sweat testing strategies

Within the good world, a sweat check would acquire sweat from the whole physique, as a result of sweat charges and sodium losses differ from one physique area to a different. The right check would additionally not intervene with the conventional operate of sweat glands, by not masking them or stopping the pure air stream to the pores and skin. While an entire physique washdown method exists that meets these standards, it’s very impractical, requires train circumstances that don’t mirror actual world sports activities, and may solely be accomplished on a stationary bike.

As a substitute, the popular technique in current occasions to be used in athletes has been sweat patches, utilized to particular websites on the pores and skin. These patches take in sweat because it’s produced. It may possibly then be extracted from the patch both by utilizing a big syringe to plunger it out, or a particular tube that may be centrifuged in a lab. The sweat pattern is then analysed for the sodium focus utilizing specialised laboratory tools. Extra not too long ago, a pocket sized electrolyte meter for sodium has been discovered to be a legitimate substitute, and can be utilized in subject settings. The sweat sodium focus is then mixed with the sweat price to find out the hourly sodium losses.

Biometric sensors for sweat testing

Latest advances in biometric sensors and wearable gadgets have led to the event of patches that may self-analyse the sweat they acquire. This protects on cautious patch removing, sweat extraction and evaluation, decreasing the necessity for expert technicians and costly laboratory tools. Disposable variations of those patches at the moment are accessible commercially.

Whatever the patch used, the pores and skin web site the place the patch is utilized have to be completely cleaned and dried prior to stop contamination. The absorbent patches which might be eliminated for evaluation ought to solely be utilized to the pores and skin for so long as wanted to gather a viable sweat pattern. Extreme sweat underneath the patch begins to dam the sweat glands and prevents their regular operate.

Sweat measurements sitting in a chair

One other technique of sweat assortment, initially developed for the analysis of Cystic Fibrosis, is usually used with athletes too. This method makes use of a pharmaceutical agent (pilocarpine) utilized to the pores and skin to induce sweating. The check is normally carried out with the athlete sitting in a chair. No train is concerned. Sadly there are at the moment no research that present whether or not or not this type of testing is an satisfactory substitute for sweat testing throughout train, and it’s subsequently not beneficial for athletes.

Concerns when sweat testing

As talked about in a earlier weblog publish, sweat sodium focus can differ with variations in sweat price. Because of this, ideally sweat testing must be carried out on the similar depth and in the identical circumstances as these you wish to apply the outcomes to (coaching or competitors day). If the coaching or competitors that you simply wish to apply the outcomes to exceeds 2 hours, keep in mind that sweat price will enhance steadily within the first half-hour of train as core physique temperature will increase from resting. Ideally you’d apply the patches after not less than half-hour of train so the check outcome displays nearly all of your occasion, not the primary half hour.

Decoding sweat testing outcomes

A number of elements have to be understood when making sense of your sweat testing outcomes. Athletes usually merely belief numbers they’re given, however in case you perceive the attainable issues with these numbers it permits athletes to make higher choices.

Regional sweat assortment versus complete physique sweat

Firstly, sodium losses at any given a part of the physique don’t mirror complete physique losses. Equations can be utilized to offer complete physique estimates, though they don’t seem to be good. If you’re having a industrial sweat check, ask the supplier if they’re reporting the precise focus obtained from the sweat pattern, or the estimated complete physique worth. In the event that they don’t know what you’re speaking about, it is a huge purple flag.

You sweat in a different way every single day

Secondly, no two days of train outside are ever the identical. Sweat price, and sweat sodium focus, will subsequently differ to not less than a point from sooner or later to the subsequent. Few research have investigated day-to-day variation in sweat sodium focus, however those who have discovered the variation was round 15%. This can be as a result of many elements, together with the sodium eaten within the days previous the check (as mentioned in a earlier weblog), small however presumably vital variations in temperature, humidity or airflow, clothes, or just pure day-to-day variation within the hormones that regulate sodium losses (this has been noticed in urine losses even with similar sodium intakes).

Variations in circumstances throughout longer occasions

Lastly, think about for longer occasions that the environmental circumstances will differ throughout even the identical day. It could be cool originally of a highway biking occasion within the morning, however the occasion finishes within the warmth of the day. Even when the identical tempo was maintained all through, sweat price would differ because of the altering climate, as would the sweat sodium losses from hour to hour. So fairly than taking the worth obtained in testing as an actual goal, consider it extra as a ball-park determine, classifying your sodium focus or losses as low, medium or excessive. Which brings us to how you are taking that outcome and apply it…

How one can use sweat check outcomes?

For all of the analysis that’s gone into perfecting the sweat testing course of, it’s fairly shocking that there’s virtually no analysis in any respect into methods to interpret and apply the outcomes! Do you change 100% of the losses? 50%? 10%? At present there aren’t any pointers or research to assist reply that query. As talked about in a earlier publish, sodium alternative doesn’t appear to affect efficiency, so the query is, what profit/s will we get from changing sodium losses, and if we do, how a lot must be changed? This can be explored within the subsequent publish.


There are totally different strategies of sweat testing, which all have strengths and limitations. At present the patch method is the popular technique of acquiring sweat samples that mirror real-world train situations. Make sure the train accomplished when the patch is utilized is just like competitors circumstances, that the patch is utilized when you’ve been sweating for a substantial time, and the outcomes are transformed to estimate complete physique losses. And keep in mind that the values obtained are a ball-park determine, not a exact quantity.


  1. Baker LB. Sweating Price and Sweat Sodium Focus in Athletes: A Overview of Methodology and Intra/Interindividual Variability. Sports activities Med. 2017; 47(Suppl 1):111-128.

  2. Baker LB et al. Train depth results on complete sweat electrolyte losses and regional vs. whole-body sweat [Na(+)], [Cl(-)], and [K(+)]. Eur J Appl Physiol. 2019; 119(2):361-375.

  3. Baker LB et al. Validity and reliability of a subject method for sweat Na+ and Ok+ evaluation throughout train in a hot-humid surroundings. Physiol Rep. 2014; 2(5):e12007.

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