How do I prepare myself for this?
In about 7 months I wanted to take part in an activity that requires me to hold 25 lbs of metal awkwardly out in front of my chest for long amounts of time (while being physically active).
I do a little bit of running and am moderately in shape (I have a fast metabolism), but I have almost no upper body strength. I've recently started to do some rowing on a Bowflex machine.
Are there any suggestions on things I can do to build endurance and upper body strength?
I am sure you have a good reason why you want to do this.
If a client approached me with this request and an assessment would find that he has good range of motion and no problems, I would suggest the following approach:
Step up cardio and include a load like a weighted vest to gradually get used to having endurance with greater load than just body weight.
Before getting too involved in the traditional upper body strengthening exercises, I would start with the muscles of the rotator cuff and upper shoulder girdle to prevent possible injuries. I would also first do a lot of body weight exercises like planks to strengthen the core. Then get into a balanced upper and lower body workout. I would probably go with squats and lunges for the lower body rather than machines. Upper body workouts can start with the standard chest and back and arm stuff but I would move toward the TRX for greater whole body involvement.
As the event draws closer, you have to start training in the way you intend to participate to develop the specific strength.
Having said all that: I am dying to know what that is!
Wish you good luck even if I never know the answer.
I love the other great advice you have been given.
Will you be playing a wind instrument? If so, I would take that on my cardio sessions and play a few measures throughout the workout, working the way up to playing the entire score that will be done in competition.
You will also want to exercise your diaphragm with deep and forceful breathing to use full capacity of your lungs.
Have fun with this compromised but enjoyable event.
One type of equipment I would suggest for you is battling rope. It's great for what you are training for because some of the exercises and movements done with the rope will help improve your strength and muscular endurance (which is needed to play that instrument). There are numerous exercises which you can do with the battling rope in which you will engage your full body. A rope which is 50 feet long and 1.5 inches thick will do the job.