A 3M model 7502 half mask respirator paired with 3M 2071 P95 filters is probably the best option available anywhere for exercising. The 7500 series respirator is made from silicone so it’ll withstand sweat while still maintaining a good seal and it can move a lot of air through its twin filters and large exhalation valve. The P95 disc style filters are probably the easiest filters to breathe out of while still maintaining adequate protection (you could move up to P100 filters but I think the added pressure resistance will negatively impact your ability to do cardio).
