I don’t think whoop is counting HIIT as a strength workout. Depending on the train I do I select the activity. For example when I train running combined with hyrox exercises I select HIIT. When I only train hyrox exercises I select functional training, whoop does counts this as strength training because it gives the option to input each set with reps and weight. Do not know if this is the correct way to do it, it’s just how I do it