Stopcecil! wrote:
Standing rests could likely lead to it being more and more anaerobic considering your heart rate drops and you have to use more anaerobic systems to get back to your VO2max. So you have MORE of a build up of lactic acid. Both types of training should be used depending on the stress you are looking for.
This^
If an athlete does VO2 max type reps at, say 3k-5k pace, the workout is more aerobically challenging if an athlete takes short rest because the athlete's heart rate never really has a chance to return to resting. The athlete may also accrue higher total blood lactate concentrations because 90 seconds just isn't enough for all of the lactate to be processed out during the rest period.
However
If an athlete does the same workout, kilos at 3k-5k pace, with longer (rests 3-5 minutes), the heart rate will drop much further during the recovery. More blood lactate will be processed and the peak blood lactate levels achieved during the workout will be lower. This does not mean the workout is any less effective, especially for 800m runners.
When HR drops back toward resting, this means the the beginning of the next rep will require more anaerobic energy input as heart rate ramps back up toward maximum. This means that the athlete will be more effectively training the glycolytic pathways, while at the same time getting a solid aerobic session. for 800 types that are mostly FT, speed power type runners, this type of aerobic power training is gold, because it more closely mimics the metabolic requirement of the target event
I understood this concept intellectually for many years, but only figured out how to put it into practice a couple of years ago. I had a kid who only ran 1:56 for me, but 2 years later went on to run 1:50.3 as a college sophomore. For most of the kid's career, he was stuck at around 1:58-2:00. It was only toward the end of his senior year, when I actually started letting him take more rest on the long intervals, that he dropped to 1:56. His college coach was not afraid to let him rest between reps and he went 1:51 high as a freshman before dropping to 1:50.3 as a soph.