Open the Lab module by navigating to lab.ontracx.com or by selecting the test tube icon in the left-hand menu of the PRO platform.
The new LAB module allows you to automatically capture data in the platform, but a performance a Chrome-based browser such as Google Chrome or Microsoft Edge is required for the best experience (Safari is not supported).
Of course, you can also still enter data points manually into the Lab using the real-time function in the OnTracx App.
Main Screen
From the main screen, you can:
Add & onboard athletes – add new athletes and gain insights into their load tolerance. (See this support article for more details.)
Browse athletes – select an athlete to view their screening history and review previous results.
Athlete data for Pro users will automatically sync with their profile in your Pro dashboard, enabling seamless linking of screening results to remote follow-ups.
Performing a Test
Access the Lab test module from the left-hand menu.
Selecting Test Type
Select Screening Type:
Load Screening
Location: choose Treadmill or Overground.
Test Configuration:
Single leg – select left or right (preferably the injured or target leg).
Both legs – measure load on both legs for asymmetry insights (requires two sensors).
Choose Athlete
Select an athlete from your list.
Execute Test
The Execute Test screen has four quadrants:
Upper Left: Speed Selection: Indicate the running speed for the athlete.
Upper Right: Sensor Connection & Real-Time Load
Tap Connect Sensor to open the connection screen.
Enable Bluetooth if it’s your first time connecting.
Wake up the sensor – touch both metal pins on the back simultaneously for <1 second.
Select your sensor by checking the unique ID on the back.
For asymmetry tests, connect two sensors and ensure each sensor is attached to the correct leg.
Lace up the sensor
Pick your leg
If you’ve had injuries, place the sensor on the leg with the most history.
No injuries? Great — choose either leg, but stick with the same one for consistency.
Strap it to your leg
Place the strap (with sensor + mount) about 10 cm above your inner ankle, on the flat part of your shin bone.
Attach the sensor to the mount
Press the pins of the sensor firmly into the mount.
Make sure the sensor faces slightly inward.
The logo and text should be upright and readable — that’s how you know it’s in the correct position.
Adjust for comfort
Tighten the strap so it stays in place, but keep it comfortable and non-restrictive. It's possible that you, while running, "kick" the sensor out of the mount. The best way to prevent this is to put your socks over the sensor.
When active and in pairing mode, the red LED stays on continuously. After 1 minute, the sensor enters standby; briefly press both pins again to wake it up.
Lower Left: Measurement Periods
Press Start to begin measuring.
The sensor will record continuously, but only the indicated measurement period is used for data analysis.
After the period ends, the average load will appear in the Lower Right Quadrant as a new data point.
Repeat this process for multiple speeds. Make sure to record data at a minimum of three different speeds to ensure a reliable analysis.
Once finished, click Finish Test to stop the sensor.
Data is stored on the sensor and can be synced to the athlete’s profile in the OnTracx app. Make sure to clear sensor data regularly.
Results
Load Analysis
Gain a clear view of how your running load changes with speed and how it compares to a broad reference group. Each data point shows whether your load falls within a low, average, or high zone, helping you understand your unique loading pattern and where you stand among other runners.
Speed Effect Analysis
The analysis gives you a clear picture of how your load responds to changes in running speed. It quantifies how much your experienced load (in G) increases per 1 km/h speed gain and highlights key transition points.
If your graph shows a biphasic pattern, it means there’s a breakpoint — a specific speed where your load starts rising more rapidly.
Based on these analysis you’ll receive practical, ready-to-use recommendations:
The optimal speed range to train within for efficient load management.
The pace at which your load begins to increase significantly.
Whether your load progression suggests the need for strength work, pacing adjustments, or closer biomechanical evaluation.
This analysis helps you translate your data into concrete training actions — so you can run smarter, not just faster.
Asymmetry Index (with two sensors)
The Asymmetry Index compares the load between your left and right leg at each running speed, giving you a detailed view of how evenly you distribute impact forces.
Higher values toward the right indicate greater load on the right leg, while higher values toward the left indicate more load on the left leg.
Monitoring asymmetry is particularly important in injury prevention and return-to-sport contexts. It helps you track whether an athlete continues to unload an injured leg or overcompensate with the uninjured side — a common pattern after injuries such as ACL reconstruction, Achilles tendinopathy, stress fractures, ...
By assessing both the magnitude and consistency of asymmetry across speeds, you gain valuable insight into recovery progress, compensatory strategies, and overall running mechanics.
Great! You’ve completed the screening! 🎉
With our new update, you can use the load screening data to generate an individualized load-based training scheme for your athlete.
The load screening also allows sensor-free running during remote follow-ups for PRO users. 👉 Learn more here.