Athlete location tracker with GNSS and IMU

Hello everybody, I am working on my own athlete location tracker, Right now I am using Local GNSS receiver (Quectel L86 module (2 Meters Accuracy)) where I am logging data into a SD card and then transferring it to Google earth. The location is not accurate as it required. Few people told me to add IMU like MPU6050, and track your body movements, Take an average of IMU and GNSS and log the data.

I don't know where to start, Can anybody help me.

P.S I have seen this tracker over the internet, They are also using the same GNSS and IMU tech to get precise and accurate location (50CM ACCURARY!)

Thank you