From the Super Mario Wiki
Weightlifting is a Weightlifting Event that appears exclusively in the Nintendo 3DS version of Mario & Sonic at the London 2012 Olympic Games. The objective of the event is to be able to lift and hold the highest weight possible. The starting record for this event is 200kg.
In the game's story mode, weightlifting appears as part of the third and fourth challenges of Wild Ones Episode 2, Corner the Koopa King!, in which Vector must beat Bowser in the event, alongside Football and Rings for the third challenge and Boxing and Double Trap for the fourth. It appears again as the fourth part of the second challenge of Wild Ones Bonus 2, The Life of a Minion, in which Bowser must beat Vector in the event along with Javelin Throw, Double Trap, Football and Rings.
At the start of this event, the player must use the control pad to set a weight to attempt to lift, starting at 130kg with a maximum of 220kg, and then press to confirm, within a limited time. An extra blue weight is added to the red ones at 160kg and an extra green one at 200kg. The player is told the weights that the opponents were able to lift, or whether they failed, while choosing their weight. The player must then initially shout, or blow, into the microphone to power up their character and move onto the lifting segment of the event. If the player fails to do this in time, a smaller yellow section appears on the gauge. The player then must blow into the microphone with the right timing to be able to lift the weights. A gauge appears at the bottom of the screen, with blue, green and yellow sections to indicate whether the weight can be lifted, and a microphone cursor which constantly moves up and down it. The size of the sections depends on the amount of weight being lifted, with smaller successful sections for higher weights. If the player shouts when any part of the cursor is in the yellow section, they will lift the weight successfully, though otherwise the dumbbell will be dropped. The player will also fail and not lift the weight if they do not blow in time.
1) Lift: Shout whatever you like at the microphone (lower screen).