What is the fine-grained topic of the following text: However, it is important to remember that Flat jockeys and Jump jockeys have different weight requirements; the former are typically lighter and shorter to facilitate greater speed in Flat racing, whilst the latter are usually taller and slightly heavier to allow for the extra strength and stamina required over the obstacles in Jump racing. Only return the topic.
Differences in weight requirements between Flat and Jump jockeys