Add exercise with sets to a session

Question

In my garmin connect iq app I do create a user session like following:

mSession = ActivityRecording.createSession({
    :sport=>ActivityRecording.SPORT_TRAINING, 
    :subSport=>ActivityRecording.SUB_SPORT_STRENGTH_TRAINING, 
    :name=>"Workout"
});

// TODO: add a set with some data + add total workout statistic
// e.g. one set of benchpresses with 10 reps of 100kg within 40seconds

mSession.stop();
mSession.save();

I can't find any way to fill the default data of this session I only find things like createField which creates user fields.

So my question is how do I fill out the default fields of a strength training session? Namely following:

• time under tension
• pause time

And additionally how do I add default list entries? Namely:

• an exercise with sets and a weight and reps?

Currently, when I save my session I don't have any data but avarage heart rate, calories and time inside my workout.