Without making a roll, a character can lift above their head approximately 10 kg of weight per point of Physical Strength, plus an extra 1 kg per point in the Lifting aptitude. This doubles if they are only trying to lift to waist height (20 kg per point in Strength and 2 kg per point in Lifting).
To lift more a character must roll Physical Strength + Lifting vs a Hard TN of 30. For every point of success the character is able to lift an extra 100 g. Every 10 points of success therefore equals an extra 1 kg of weight lifted.
If a character fails a lifting roll by more than 30 points, the GM may rule they have suffered a muscle injury of some kind. If that happens any further physical activity will have a -20 penalty applied to the TN and they will no longer be able to move faster than a jog.