Runners at all levels are increasingly moving from emergency cross-training to supplemental cross-training, where one or more alternative cardio activities have a small but consistent place in one’s training program. For example, a typical supplemental cross-trainer might run four times a week and use an elliptical trainer twice a week instead of running six times a week.
This approach has a few advantages. First, it reduces injury risk by limiting the repetitive impact of running without much if any sacrifice of running-specific fitness. A second advantage of supplemental cross-training is that it keeps runners well adapted to their chosen alternative cardio activity so that they are able to get more out of it if an injury forces them to rely on it exclusively to maintain fitness for a period of time.