<P> The wave (known as a Mexican wave in the English - speaking world outside North America) is an example of metachronal rhythm achieved in a packed stadium when successive groups of spectators briefly stand, yell, and raise their arms . Immediately upon stretching to full height, the spectator returns to the usual seated position . </P> <P> The result is a wave of standing spectators that travels through the crowd, even though individual spectators never move away from their seats . In many large arenas the crowd is seated in a contiguous circuit all the way around the sport field, and so the wave is able to travel continuously around the arena; in discontiguous seating arrangements, the wave can instead reflect back and forth through the crowd . When the gap in seating is narrow, the wave can sometimes pass through it . Usually only one wave crest will be present at any given time in an arena, although simultaneous, counter-rotating waves have been produced . </P> <P> While there is general disagreement about the precise origin of the wave, most stories of the phenomenon's origin suggest that the wave first started appearing at North American sporting events during the late 1970s and early 1980s . Krazy George Henderson perfected the wave at National Hockey League games, followed later by the earliest available video documentation of a wave, which he led on October 15, 1981 at a Major League Baseball game in Oakland, California . This wave was broadcast on TV, and George has used a videotape of the event to bolster his claim as the inventor of the wave . On October 31, 1981, a wave was created at a UW football game against Stanford at Husky Stadium in Seattle, and the cheer continued to appear during the rest of that year's football season . Although the people who created the first wave in Seattle have acknowledged Krazy George's wave at a baseball stadium, they claimed to have popularized the phenomenon . </P>

When do you do the wave at a baseball game