Updating Lactate Threshold From App or BLE Device

Hello,

I understand Garmin has an estimated Lactate Threshold training guided measurement feature. Is there an API call or mechanism for an app running on the Garmin device, or an external device using BLE to set/adjust this parameter? Or the VO2Max parameter?

I've reviewed the API and feel that I could step through BLE communications and UI aspects of an app without help. What I am unable to determine is how to set the actual values, e.g. "LactateThreshold.set (value)" or similar option. Given the correct method to set the parameters, I feel I could connect the dots. Is it possible in the newest APIs to set these values? Any pointers would be appreciated. 

Background: occasional Android Developer with Fenix 6. First Garmin app. Extensive non-"app" software development. Have used watch for a year now (running, bike and sailing).

Thank you for any assistance you are able to provide.

Ed