What are the best workouts to improve 400m time?

run repeat 300s @ 80% improve speed off first straight , curve, run repeat 600s endurance finish race strong @ 75%, gradually building 85% running 800. in weight room , work core , legs. breathing exercises , come race plan.

race plan pretty simple,
first 5-7 strides out of blocks go out @ 100%, trust me wont reach top speed.
first 50m first straight, begin stand tall, maintaining current speed , not accelerate
200m mark, begin accelerate , pump arms harder , faster
home stretch, accelerate , pump arms fast,but keep shoulders relaxed, , stand tall, not break form because slow down.

lastly, if feel breaking down, visualize finish line , dont stop till after pass line 5-10 meters.

so season barely starting , want know workouts can benefit 400m. ran 52 last year freshman. ideas?

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