- Clean, dry skin: sweat is the biggest source of error.
- Wipe away the first drop, measure the second.
- Do not squeeze. If no more blood comes, prick again.
- Hold the strip to the drop; do not press it onto the skin.
The measurement itself takes ten seconds. Whether the value is right is decided in the half-minute before. With these instructions you can take a clean sample, from yourself and from your athletes.
What you need
- Meter with the code chip from the current box of strips
- Test strips that match your device
- Lancing device with a new lancet, or single-use safety lancets
- Dry swabs, plus alcohol pads in case you cannot wash your hands
- A rigid container for used lancets and strips
- Disposable gloves if you are measuring other people
Fingertip or earlobe?
The instructions for use of the test strips describe sampling from the fingertip. In performance diagnostics, samples are often taken from the earlobe. There are reasons for both.
| Feature | Fingertip | Earlobe |
|---|---|---|
| Access | Easy, even when you are measuring yourself | Easier with a second person |
| Sensation | The prick is more noticeable | The prick is barely noticeable |
| In a step test | The site closes quickly; you often have to prick again | The site stays open longer; one prick is usually enough for several stages |
| On the bike | One hand has to leave the handlebars | Both hands stay on the handlebars |
One thing matters above all: stick to one site, within a test and from test to test. Values from the finger tend to be slightly higher than values from the earlobe. The Lactate Express study (see Chapter 2) took its samples from the earlobe.
Step by step
Lay everything out
Device, strip vial, lancing device, swabs and disposal container are within easy reach. The code chip from the current box is in the device. Device and strips are at room temperature.
Wash your hands
Warm water and soap, then dry them well. If that is not possible, use an alcohol pad and wait until the alcohol has evaporated completely.
Clean and dry the site
Wipe off sweat thoroughly with a dry swab. There must be no cream or lotion on the site.
Insert the test strip
Take a strip out of the vial and close the vial again immediately. Push the strip into the device; it switches itself on. Compare the code on the display with the code on the vial. Do not touch the tip of the strip. From now on you have two minutes.
Prick
Prick the fingertip or the earlobe with a new lancet. Avoid moles and swollen or inflamed areas.
Wipe away the first drop
The first drop may contain tissue fluid, skin particles and traces of sweat. Wipe it away with a dry swab.
Let the second drop form
Stroke gently towards the puncture site until a round drop has formed. Do not squeeze. If no more blood comes, prick a new site.
Hold the strip to the drop
Bring the tip of the strip to the drop without pressing it onto the skin. The strip draws the blood in by itself. The Lactate Express confirms with a beep that the amount is sufficient.
Read the value and tidy up
After 10 seconds the value appears on the display. Note it down or transfer it to the app. Eject the strip using the slider, dispose of strip and lancet in the disposal container and press a swab onto the puncture site.
In a step test: quick and consistent
In a step test you measure at the end of each stage. Sampling should then take no longer than about 30 seconds, so that the break stays short and the same at every stage.
- Keep the strip vial within reach. Take each strip out only shortly before the measurement and close the vial again straight away.
- Wipe the site again before every sample. You sweat more with every stage.
- Discard the first drop for every further sample too.
- For each value, note the stage and the heart rate at the end of the stage.
The most common mistakes
| Mistake | What happens | How to avoid it |
|---|---|---|
| Sweat in the drop | The value comes out far too high, because sweat contains a lot of lactate. | Wipe dry, discard the first drop. |
| Squeezing | Tissue fluid mixes with the blood and distorts the value. | Stroke only gently; if in doubt, prick again. |
| Too little blood | The reaction zone does not fill, and the device reports an error. | Take a new strip, wait for a larger drop. |
| Strip pressed onto the skin | The inlet is blocked, and the blood is not drawn in properly. | Touch only the drop. |
| Damp or old strips | Incorrect values. | Close the vial immediately, check the expiry date. |
| Cold or heat | Incorrect values or an error message. | Measure at 15 to 35 °C, let the device acclimatise. |
| Alcohol still wet | Alcohol residue can distort the measurement. | Let it dry completely. |
Hygiene and safety
- Every lancet is used only once.
- A lancing device belongs to one person. Anyone measuring several athletes uses single-use safety lancets.
- Wear disposable gloves when you take blood from other people.
- Used lancets and test strips belong in a rigid, sealable container.
- Clean the device after use as described in the manual.
The instructions for use supplied with your device and the test strips are authoritative. They also contain the manufacturer’s specifications for taking the sample.