Mel,
According to last year my limiter seems to be my muscular endurance. My legs will tire out well before I go anaerobic while running or on the bike. Naturally I'm trying to lay down a solid foundation of strength during _base_. As for lifting, would it be to my benefit to focus on maximum weight like 4x6 or something with a moderate weight at 3x10?

Thanks,
-Kim

Kim,

I would focus on plyometric movements with body weight... like jumping squats, burpees and jumping lunges. I think that building lactic capacity through strength movements helps your body develop some ability to handle the anaerobic component of these power movements (that are required for mountainbiking) and lifting your body weight versus isolating one muscle groups will strengthen all of the small muscles that stabilize you during the pedal stroke or run stride. You will get more bang for your buck doing that stuff.