In the race, after the acceleration phase, it is important for the sprinters to run in as relaxed a mode as possible up to the 250-300m mark, when the lactid acid starts building up.
From then on, the aim is to lose as little as possible.
The best lanes are 3,4,5 and 6.
The bends for the athletes in the inner lanes are tight while those in outer lanes can't see their competitors.
The 400m is a lot about sprint endurance and the runners undergo a lot of lactic acid training in order to cope with the last 100m of the race.