2013 Grand National to modifications made for the previous year's race, Aintree announced that a number of further changes had been made for the 2013 National. Twelve of the 16 fences on the course were rebuilt with the timber frames within them replaced by a softer material known as "plastic birch". The fences are still covered with at least 14 inches of spruce and will remain the same height. The starting line was also moved 90 yards closer to the first fence, further away from the spectators' stands and thereby reducing slightly the overall distance. Aintree and the Professional Jockeys' Association jointly issued
National Hunt racing is run over a distance of more than 4 miles, there are up to 40 runners, the course at Aintree is essentially flat, and the horses are handicapped (the best horses carry the most weight). Perhaps the most fundamental difference is that the Grand National fences are far bigger than the fences at Cheltenham, and a number of fences incorporate significant drops. The most famous fence is Becher's Brook which is 5ft high, but has a 7ft drop on landing and is widely regarded as the biggest challenge on the course. Famous winners of the Grand National include Red Rum