A:

First, running practice is an auxiliary practice of breaststroke.

Second, the land should also be increased:

1. Squat with weight.

2. step and leap.

3. Take off in place.

4. Climb the mountain.

Third, the 400-meter breaststroke may reach 4 minutes and 30 seconds.

But there is still a need:

1. Watch your hand movements.

2. Pay attention to the body wave line.

3. Pay attention to the coordination of hands, feet, body and breathing.