Hard interval training will work well for you if you have an excellent aerobic base.
Most people do too much Hard Interval Training, which is 10 x 200 and above.
Most of the year one should be strengthening the aerobic system and pairing it with at least one day per week of sprints/hills of 80 meters or less. See Ryan Hall, 2:04 marathoner for that one. ALL distance runners need to pay attention to that principle because, "You can be as strong as an ox, but if you cannot make the wheels spin fast, you are in trouble." Ryan Hall
Hall also ran a 13:16 5K.