originally a 200/400 guy in high school. 48 low 4x4 split consistently in college when i moved up to the 800. sprint background never ran any mileage before. started adding quality mileage 40-50mpw consistently for around a year now. 800m PR of 1:54. is there potential to get to that next level moving up to the 1500? i cannot run pace under 5:20 for 4 miles to save my life. this has been one of my "aerobic development goals". any advice from sprinters who moved up? if it makes a diff i prlly have low 22 200m speed..