Hi Nathan6,

It would help if you could give us a basic idea of where you are now and what you're thinking of trying. What do you typically do in a week (what, how fast/long, etc.), what are your goals for next year's season, and how much time do you have for training? Also, how much background do you have in swimming, biking, and running?

Generally, doing "other" activities can help you, just make you tired, or hurt you, depending on what they are and how compatible they are with your plan.

For example, if you are primarily a cyclist, and you want to make your harder days harder, don't do an hour on the stairmaster on your off days. You'll just get tired and make your harder days easier than you want them to be. Instead, doing an easy half hour spin on the bike will help you recover and get you rested and ready for the next day's hard ride.