User activity history: hot to get details about multisport activity parts?

I'm currently trying to create a data field that compares the current timer time of the activity with the duration of yesterday's activity of the same type.

This works well unless yesterday's activity was multisport. I'm not able to get the information what is contained in the multisport activity. I only get a single activity of type 18 (SPORT_MULTISPORT) without being able to distinguish whether it contains activities of the current type.

Is there any way?

 var userActivityIterator = UserProfile.getUserActivityHistory();
 var activity = userActivityIterator.next();

 while (activity != null) {
 System.println("Activity type: " + activity.type + " Distance: " + activity.distance);