Does momentum exist? Most athletes and coaches say yes, but psychologists say that it's really about how players tune themselves in and out of games, and when they put it to rigorous testing, they often find it is tough to measure.
This weekend, sports fans can tune into the World Cup in Brazil, the NBA finals or the NHL finals. In each case, teams are relying on momentum to carry them through each match, as well as mutli-game championship tournaments.
"Psychological momentum is objective in the sense that if you are up you have the momentum," said Richard Lustberg, a sports psychologist in New York City who works with many athletes. "It's whoever is ahead."
Lustberg works with professional and amateur athletes to help them get the best out of their game. He says that momentum is often something that can be instilled by coaches on the sideline or team leaders on the field or court. When a team is losing, the players need to figure out how to reconnect to the finely-tuned athletic skills that got them there in the first place.
"It's extremely important how coaches interact and give the team some plausible cause why they can recover and win," Lustberg said. "One of the crucial things is how they coach or the leaders of the team come in and give them a reason to believe."
That could be happening today in two lockers room as the New York Rangers try to come back from a 3-1 deficit against the Los Angeles Kings for the NHL title, and as the Miami Heat try to rebound from a 3-1 deficit against the San Antonio Spurs in the NBA.
Lustberg says that for either the Rangers of Heat to win, the entire team needs to remain focused on the game, including the bench-warmers. He does this with his athlete-patients.
"I have the player focus on the game rather than on his performance," Lustberg said. "I make him an observer of the game so that he's an active participant."
Academic researchers still appear to be divided on whether the concept is real or not, according to several academic papers.
An study of Wimbledon tennis matches in the mid-1990s found small positive and negative effects of momentum, while another in 2012 found evidence for psychological momentum in hockey, especially right after a fight between opposing players.