It is important to do cardio in the winter
One of the best alternatives – swimming. Yes, swim! This is probably the best alternative after sprints . Swimming is a great substitute because it can be implemented as endurance (long-distance ) and Explosion ( short distances). Furthermore, an overload of the upper body, and specifically the back and arms , which will increase your results in the gym .
Naturally, the disadvantage of swimming is that it does not excercise enough the legs and lower body as a whole. Therefore , for maximum effect , combine swimming with some form of interval cardio . The best option in the winter would be swimming + climbing stairs / hill. This maintains the your condition , and even improves it , while at the same time loads your body in different ways. In any case, you win! If nothing else , maybe for a moment you feel like Michael Phelps .
So try swimming as an alternative for several weeks. Who knows, you might even like it more than running.