If reps are being skipped, or velocities jump around between reps that looked identical, work through the checks below in order. In our experience the first two account for most cases.
1. Check the sensor's calibration first
This is the most commonly missed cause. A sensor calibrated on a surface that wasn't level will still connect and record normally - but it can miss reps, and the metrics it produces are not valid.
Open Sensor Settings in the Capture app and check Calibration Status. If it shows anything other than Updated & Calibrated, recalibrate before troubleshooting anything else. See My sensor still says "Calibration Required" after calibrating.
2. Check how the sensor is mounted
A sensor that shifts mid-set will produce exactly the pattern coaches describe - some sets fine, some sets with wild rep-to-rep variation.
• Tighten the strap so the sensor cannot move or rotate on the bar
• Mount it close to the centre of the bar rather than out near the sleeves
• Position it so it does not make contact with the athlete's body at any point in the movement
• Check the placement is right for the exercise - the ? button inside each exercise shows the correct placement, and there is more in Exercise Instructions & Strap Information
If straps have stretched or the velcro has worn out through heavy use, contact us for replacements.
3. Use the countdown, and start the movement at zero
This single change resolves a large share of missed rep reports, particularly on explosive lifts like cleans and jerks.
Turn on the 5 second countdown before each set. Coach your athletes to unrack the bar and get fully set during the countdown, so the first rep begins exactly as the timer hits zero.
Unracking after recording has started gives the sensor movement to interpret before the actual lift, which is a common source of both missed and spurious reps.
4. Consider the movement itself
Some velocity variation is real rather than a measurement problem. A rep finished with a pronounced stop at the top will read differently from the same rep finished continuously. If athletes are inconsistent about how they complete the movement, the data will reflect that. It is usually easy to cue and worth doing before assuming a fault.
If you are seeing consistent discrepancies at particular loads, or on a specific exercise only, tell us - that pattern is genuinely useful diagnostic information.
5. Rule out connection and battery
• The sensor has a range of roughly 10 metres from the tablet or phone. Place the device centrally rather than at one end of the area
• Check the battery - a sensor flashing red is at about 10%
• Make sure the Capture app and the device OS are both up to date
If reps are dropping out part-way through sets across several racks, see Sensor keeps disconnecting during a session.
6. Report the set while it is still on screen
This is the most valuable thing you can do, and it has to be done straight away.
When a set goes wrong, scroll to the bottom of the review screen and tap Report Issue, with a short description of what happened. This sends the raw file to our tech team, who can see exactly what the sensor recorded.
Important: Reporting an issue needs an internet connection, and can only be done immediately after the set is completed. Once you move on, the option is gone. See How to report an issue within the Capture V2 app.