Sweat Sodium Testing
Sweat sodium testing for athletes is rare in New Zealand. Tristar Performance is one of very few test centres in the South Island — and the only one in Canterbury. If you've been looking for this test, you've found it.
$229
What is it?
A sweat sodium test measures the concentration of sodium in your sweat: a number that is unique to you, largely genetic, and one of the most overlooked variables in endurance performance. Hydration advice for endurance athletes is almost always built on averages. Drink this much, take this many electrolytes, follow the label.
The problem is that sweat sodium concentration varies by as much as a factor of ten between individuals: a low-salt sweater losing 200mg per litre needs a completely different strategy to a high-salt sweater losing 2,000mg per litre.
If you've ever cramped in the final third of a race despite drinking consistently, felt nauseous or bloated during an Ironman, or crossed a finish line completely wrecked when your training said you shouldn't be — sodium imbalance may have been the factor you never knew to look for. At its most serious, a poorly matched hydration strategy can contribute to hyponatraemia, a potentially dangerous drop in blood sodium during prolonged exercise.
The sweat sodium test removes the guesswork entirely.
How we test
We use the Precision Fuel & Hydration Advanced Sweat Test — the same methodology used by professional endurance teams and elite athletes worldwide. This is a clinical-grade test using pilocarpine iontophoresis, a technique that stimulates a small patch of skin (typically the forearm) to produce sweat in a controlled and measurable way, without any exercise required.
The process is simple, painless, and takes less than 30 minutes. A small sensor is placed on your forearm, a mild electrical current stimulates local sweat production, and the sweat is collected and analysed to determine your precise sodium concentration in milligrams per litre.
No running. No cycling. No working up an actual sweat.
What the results tell you
Sweat sodium concentration — your precise sodium loss per litre of sweat, in mg/L, classified against the PF&H population range
Sweat type classification — low, moderate, high, or very high sodium sweater
Personalised hydration strategy — specific recommendations for pre-loading, during-exercise electrolyte intake, and post-exercise replacement based on your result and your target event duration
Product guidance — practical recommendations for electrolyte products and concentrations matched to your sweat profile
For events over 60–90 minutes, sodium replacement becomes a meaningful performance variable. For events lasting several hours — an Ironman, an ultramarathon, a long cycling sportive — getting it wrong is one of the most common and most avoidable causes of mid-race deterioration.
-
This isn't just for endurance athletes — it's for any athlete who wants to take hydration off the list of variables they're currently guessing at.
It's also relevant for athletes who have experienced any of the following in longer events without a clear explanation:
Cramping
Bloating
Nausea
Performance deterioration in the final stages
Sodium imbalance is a frequently underdiagnosed factor in all of these — and it's something a sweat test can identify directly.
-
Allow 30–45 minutes including set-up, the stimulation and collection period, analysis, and results discussion.
-
Arrive normally hydrated — don't over-drink water beforehand
Avoid applying lotions, creams, or sunscreen to your forearms on the day of testing
No specific fasting required
Comfortable clothing with sleeves that can be rolled up easily
All prices NZD inclusive of GST. Includes full results report and debrief.