Home-Field Advantage Has Hormonal Origins

June 20, 2006 — -- Win or lose, it's not necessarily how you play the game.

It may also be how your body responds chemically to a forthcoming game, research indicates.

Previous research has shown that the chemical credited with machismo -- testosterone -- actually increases in male athletes before a competition.

Two new studies also show how the hormone may especially peak before home games, and that female athletes likely experience the same hormone flux.

The first study, of male ice hockey players, found higher testosterone levels in athletes competing at their home rink, compared to playing an away game. The other, a Portuguese study of female soccer players, found that they produced higher than normal levels of testosterone in anticipation of a game, similar to male athletes.

Both studies were presented this week at the International Congress of Neuroendocrinology Meeting in Pittsburgh.

Testosterone is a steroid hormone that is normally associated with male puberty -- causing boys to become men. Throughout the life span, however, testosterone is related to muscle growth, assertive or competitive behavior, and risk-taking -- factors that can help athletes of either gender perform better, said Canadian researcher Justin Carré at Brock University in Ontario.

"It's important in competitive sports," he said.

Protecting the Home Turf

The "home-field advantage" may have more to do with biology than a familiar arena with roaring fans.

Canadian researchers tracked testosterone levels in saliva from four ice hockey teams. They found higher pregame testosterone levels for home games and lower levels in away games.

The "home-field advantage" may be a remnant of animal instincts to protect the home turf. When an intruder challenges the animal, it gets ready to fight with high testosterone levels.

"Humans defend their home territory," Carré said. "Much like rodents and lower primates."

Athletic games are similar to animal competitions, where animals fight in order to establish who is higher in the pecking order.

The hockey players also had high testosterone levels after winning, with a drop of the hormone after losing.

High testosterone may encourage the winner to challenge others. Low testosterone can indicate the loser should be submissive and back off from future status competitions.

"A winning streak may have a hormonal influence," Carré said. The high testosterone levels after a win influence future behavior, encouraging winners to compete more assertively in future challenges.

Carré also found higher levels of cortisol, an important stress hormone, when teams played at their home stadium. This could be related to the pressure of family and friends watching, and the greater pressure of winning at home.

Female Athletes Benefit, Too

While women have less testosterone than men, researchers found that female athletes still underwent a hormonal rush, too.

"We found the same [testosterone] response in women -- which was not expected," said researcher Rui Oliveira of the Institute for Applied Psychology in Lisbon, Portugal. Although the response was similar, the testosterone levels found in women were lower than levels found in men.

Oliveira collected saliva from players on both teams before and after the Portuguese Female Soccer League's final match in 2004. The players had high levels of testosterone before the match, compared with their saliva samples from a nongame day.

Testosterone levels found in saliva are "highly correlated" to testosterone levels in the body, according to Oliveira.

Just like the male hockey players, the winners maintained high levels of testosterone after a match, while the losers had low levels of testosterone.

"When you are defeated, [the reduced level of hormone tells you] it's a good idea to accept the loss," Oliveira said.

The hormone levels also mirror the athletes' moods.

Not surprisingly, the winners were in a better mood than the losers after the game's completion, according to questionnaires administered before and after the match.

Oliveira said that similar testosterone changes occurred in nonphysical sports, such as chess, and even in the spectators who watched athletic competitions.