Re: Burst training
When I was racing mountain bikes at a recreational level (>15 years ago), it was typical to do <span style="font-style: italic">both</span> HIIT and endurance training as part of a balanced training program. Back then, the following was believed:
1) Endurance work is better for fat loss (this would now seemed to be highly debatable).
2) Aerobic exercise (heart rate of 60-80% maximum heart rate, or MHR) could be performed pretty much endlessly with little concern for recovery, but had little benefit in terms of <span style="font-style: italic">improving</span> the fitness of an already-fit individual.
3) HIIT, performed to a sufficiently high level of intensity (heart rate upwards of 90% MHR) was the way to increase VO2max (maximum volume of oxygen uptake - a key indicator of aerobic fitness).
4) HIIT, performed to the above described level of intensity, required a recovery period of 1-2 days and thus could only be performed a couple times per week.
5) Avoid heart rates in the 80-90% MHR zone. Training in this zone has all the drawback of HIIT (namely, it requires a day or two of recovery), and yet does not offer the benefit of VO2max improvements. Most people, if you ask them to train as hard as they can, will naturally find themselves in this "no man's land". This is where a heart rate monitor is invaluable.
In this case, the goals were functional in nature; i.e. we were trying to ride bikes faster and not look better or hit a certain target body fat percentage. Since riding mountain bikes has both aerobic and anaerobic aspects, it made perfect sense (at least at the time) to train the body in both ways.
Even though I no longer race, my training (on a much-reduced level) tends to reflect this philosophy - I desire versatility over all else, and so I still utilize both types of training.