Polarised versus time crunched HIIT -a question
A couple of interesting discussions have come up since I got back on the horse but rather than continue to pollute those conversations I thought it appropriate to post a new thread. My own understanding of the situation...
Performance improvement requires a certain amount of training stimulus to drive adaptations that subsequently enable greater athletic achievement. On average this stimulus must be matched with recovery time.
Given unlimited time to play with Polarised training appears (to me), to be the best approach for long term endurance and building robust fitness. This approach; lots of time of which a large percentage at low intensity, leads to a less fleeting high level of fitness and greater resistance to set backs. For best performance over shorter time periods HIIT appears to be required also, but it is not clear to me that it is necessary if you don't care about shorter efforts.
The maximum training load is limited by the ability to recover, so for those who can devote the time it becomes necessary to use a lot of Z2 (sub LT1), because if you don't then the training stress will ramp up to the point of failure. Equally there are allegedly some adaptations that are driven by Z2 time that are useful/important for endurance, robustness, a more lasting fitness plateau etc.
Time crunched people who want to achieve similar performance gains are better served by spending a larger percentage of their time at a higher intensity because they a, have limited time and therefore need to be at a higher intensity in order to generate the stimulus for improvement and b, they are less limited by recovery as they have a lot more time when they are not exercising. Also, if all your target goals are for relatively short events, then perhaps a time crunched HIIT plan is just a more accurate `event specific' training approach.
However, recent posts in threads point to glycogen storage and some other arguments to promote polarised (Z2 Stephen Seilor), over HIIT Coggins type plans. I appreciate the physiology is a big subject and complex beyond a simple forum post, but I am curious to improve my understanding..?