Personal Trainer: Walking allows up to four users to track their walking, jogging or running activities through a series of graphs, charts and statistics, as well as set goals for themselves. The game is packaged with two wireless pedometers that communicate to the game the user's walking data. Additional pedometers will be sold separately.
The game uses Miis to track each user's progress, and allows users to either create a Mii in-game (A first for the Nintendo DS), or wirelessly transfer an existing Mii from a Wii console's Mii Channel to their Nintendo DS. The game also features a number of minigames to unlock, and users can also upload their data online via the Nintendo Wi-Fi Connection to add to weekly leaderboards and a world step count that plots a virtual trek across the solar system.
https://en.wikipedia.org/wiki/Personal_Trainer:_Walking