Taking up Pokemon Go can increase a player's daily number of steps, a study says.
But the novelty of increased activity dropped off six weeks after the initiation of the game, researchers said.
Animated Pokemon monsters first became popular in the 1990s and have featured in computer games, films, television programmes, and recently in smartphone game Pokemon Go.
The smartphone app is an augmented reality game in which players search real world locations for cartoon characters appearing on their smartphone screen.
Since its launch in July 2016, the game has been downloaded more than 500 million times.
US researchers examined the daily number of steps undertaken by players before and after they installed the game on their phones of 1182 study participants aged 18 to 35.
In the four weeks preceding the launch of the game, participants walked an average of 4256 steps each day, with almost half the group going on to play Pokemon Go.
In the first week after installing the game, players increased their average daily steps by 955 additional steps, but the following weeks saw a gradual reduction and the effect was lost after six weeks of game playing.