I've started to talk about muscle fibre types it may be worth thinking about your own muscles and are you more fast or slow twitch? How do you know?
There are two major clues, the first being what is your body type?
The word somatotype is used to categories the three types of body shape. The first being Ectomorph which is used to describe someone who is very lean and tends not to put on too much body fat and has a high percentage of slow twitch muscle fibres and is suited more to endurance activities.
In the middle is Mesamorph which tends to be more bulky, broader shoulders and probably has a more even distribution of fast and slow twitch fibres.
Then we have Endomorph which has a higher percentage of Fast Twitch fibres and more suited to power events. In the cycling world you could say Chris Hoy is more towards the Endomorph and Bradley Wiggins is the Ectomorph.
Your body type will effect the response you get from weight training