Sweat collection for sodium analysis
This single session is designed to capture two things at once: your sweat sodium concentration and your sweat rate. Following the instructions closely will give you valid data for both. Accurate sweat rate calculation requires replicating race-day conditions as closely as reasonably possible..
Your kit includes
Alcohol swab
Tegaderm + pad dressing
Tweezers
Sample collection tube + cap
Sharpie / permanent marker
Return mailer
Before you begin — read carefully
- This session captures both your sweat sodium concentration and your sweat rate. Sweat sodium is relatively stable across conditions, but sweat rate is highly dependent on environment, intensity, and nutrition. So, the conditions below matter primarily for getting an accurate sweat rate.
- Use the same exercise modality as race day: bike or run for single-sport athletes; your choice for multisport.
- Target your projected race intensity throughout — not easier, not harder.
- Replicate environmental conditions as closely as possible. Look up current temp and humidity via your local airport weather ("BOS weather," "KOA weather," etc.).
- Take your race-day nutrition exactly as planned — fluids, electrolytes, and calories. Record the precise amount consumed during the full workout duration.
Pre-workout
Weigh in
1
Warm up for 30 minutes.
2
Empty your bladder completely.
3
Towel yourself completely dry. Step on the scale nude, holding all food and drink you plan to consume during the effort. Record your starting weight on the form below.
Pre-workout
Prepare the collection site
4
Locate the anterior (inner) forearm — the site where you'll apply the dressing.
5
Using the alcohol swab, clean the site starting at the center and wiping in ever-increasing concentric circles outward.
Start at the center and wipe outward — do not re-touch the cleaned area
6
Do not touch the cleaned area once wiped.
7
Apply the Tegaderm + pad dressing over the cleaned area, pressing the adhesive edges firmly to seal.
Positioning the dressing on the inner forearm
Pad fully applied and adhesive sealed
During workout
60-minute race-intensity effort
8
Perform a 60-minute effort at race intensity. Take nutrition exactly as you would on race day. Keep precise track of every fluid consumed.
9
Monitor the pad throughout. If it becomes fully saturated before 60 minutes, or starts to detach from heavy sweating, move immediately to sample collection — do not wait for the full hour.
The pad only needs to stay on until fully saturated. If it is falling off, that is your cue to collect now.
Post-workout
Collect the sample and weigh out
10
Peel off the Tegaderm + pad carefully. Do not touch the gauze pad itself at any point.
11
Using the tweezers provided, grasp a corner of the gauze pad, gently separate it from the adhesive backing, and place it into the sample collection tube. Cap the tube tightly.
Grasping the corner — avoid touching the pad surface
Tweezers in hand, separating pad from adhesive
Dropping the pad into the collection tube and capping tightly
12
Write your initials on the cap or tube using the Sharpie or permanent marker.
13
Towel yourself completely dry. Step on the scale nude, holding any remaining food, drink, empty bottles, and wrappers. Record your post-workout weight and exact exercise duration on the form below.
Mail
Return the sample
14
Mail the sample back as quickly as reasonably possible using the return mailer included in your kit.
15
Send to:
Breakthrough Performance Coaching, LLC
433 Linebrook Road
Ipswich, MA 01938
Ipswich, MA 01938
For sweat rate instructions, visit BPC Resources → Sweat Rate Calculator
Submit your session data
Fill this out immediately after your workout. Your submission is logged and forwarded to your coach.