i have started playing rugby for a university team and have noticed im quite alot smaller then most of the other players which probably isnt the best thing, so i was wondering what supplements can i use to bulk up as fast as possible?
cheers for any help
Depends what you mean by "bulk up". If you simply want more mass, then just EAT MORE. If you're talking muscle mass gain, then you still need to eat more, but you also need to train hard in the gym, and it won't be a FAST process. However, you want to make sure that your muscle is FUNCTIONAL and not just gaining size.
Also a note that being "small" is not necessarily a BAD thing. It will depend on your POSITION. Also, training for strength, anaerobic power, speed, and endurance would be key areas for you to focus on, instead of just hypertrophy.
At your age I wouldn't recommend supplements other than the staples: Creatine, protein, multivitamin, and good fats, with creatine and protein being your primary concerns.