How do I improve pure sprint speed without having very many "16 x 100" type workouts? I thought I'd do something like 4-8 x sprints on grass after my easy runs, but I'm a little worried I won't fully recover from the workout the day before. Considering the sprints will be at 95% effort, about 80yds long, and with full recovery between sprints, will I be able to improve speed and still recover between workouts?