There are many differing factors to consider when training for strength and endurance. Mostly, it’s encouraged to train for them completely separately, but at other times they can be combined. The main variables are the duration and the intensity of training.
In order to boost endurance, workouts need to be completed at a low-moderate intensity which can be sustained for hours, working just underneath your anaerobic threshold. The benefit of this is that it doesn’t require as long to recover, reducing the likelihood of injury.
A classic example is the long weekend ride, where you can maintain conversation while sustaining a consistent output of pace. On the other hand, strength training requires high power and explosive movements, which needs to be done more sparingly and with periods of recovery in between. Strength training should make up no more than 15% of your overall weekly training volume.
Triathletes can and should include both forms of training in their regular routines. We’re predominately endurance athletes, but at times we require the ability to engage more strength. For instance, both hill climbs and overtaking demand the ability to work anaerobically for a short period of time.