I have this one cycling routine that I love. It's just loops on a 6-mile path which has fairly hilly, including two fair-sized hills. I usually do 3-4 loops (takes 60-90 minutes). This essentially ends up being a fartlek workout: mixed periods of hard exertion, near-rest, and areas in between, of varying lengths. On occasion, I do more (up to 4 hours).
Now, I know that trianing plans for endurance athletes usually consists of varying workouts, including long aerobic work, occasional LONG workouts, sprints, lifting, etc.
I don't really have strong goals but would still like my workout to be effective in the sense that my climbing and endurance improve, and also measures of fitness I'm not calculating like V02 max, body composition, etc.
What am I missing out on by doing only fartleks? (I know I really should lift, but I don't have gym access right now). I feel like fartleks have both aerobic and anaerobic elements -- but does combining them like this have the same effect?
Oh and another question - how does length of the fartlek workout matter? In my case doing it for longer would make the workout more aerobic since I would pace myself.