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's unique to you, largely genetic, and one of the most overlooked variables in performance and safety under heat stress. This matters for endurance athletes chasing a finish line, but it matters just as much for anyone working hard in hot conditions, tradies, factory and foundry workers, outdoor labourers, military and emergency services personnel, where getting hydration wrong isn't just a bad race, it's a real health risk.
Hydration advice 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, crossed a finish line completely wrecked when your training said you shouldn't be, or struggled through a long shift in the heat with no clear reason why, 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 exertion.
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
Your sweat sodium concentration, your precise sodium loss per litre of sweat in mg/L, classified against the PF&H population range
Your sweat type classification, low, moderate, high, or very high sodium sweater;
A personalised hydration strategy covering pre-loading, during-exercise electrolyte intake, and post-exercise replacement, based on your result and your target event duration;
And practical product guidance matched to your sweat profile.
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.
Who is this for?This isn't just for endurance athletes; it's for anyone who wants to take hydration off the list of variables they're currently guessing at. That includes people working in hot environments, tradies, foundry and factory workers, outdoor labourers, military and emergency services personnel, where getting sodium and fluid replacement wrong isn't just a performance issue, it's a safety one.
It's also relevant if you've experienced any of the following in longer events without a clear explanation: cramping, bloating, nausea, or 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.
How do I prepare?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.
How long does this take?Allow 30–45 minutes including set-up, the stimulation and collection period, analysis, and results discussion.