At ESS Performance, our recommendations on HIIT as an option for athletes hoping to develop their endurance are given in a fairly specific context.
As we mostly deal with athletes, most of the people in our demographic have already developed a reasonable fitness base.
The explanation below is a bit detailed and technical but we hope it demonstrates the amount of thought that we always put into choosing the right training stimulus for athletes in our program.
With middle-long distance running (assuming we are talking roughly 2-10km) the biggest limits to progress will be
Vo2max is the most amount of oxygen a person’s body can consume, process and use to produce ATP (Adenosine triphosphate).
We know that athletes (apart from long distance runners) often go above this point which means they move into a zone of using more energy than their bodies can produce aerobically. This crossover point
This often results due to the nature of most team sports which generally require periods of maximal effort and periods of recovery where the athlete is either stationary or moving sub-maximally.
And there are two main metabolites at play here:
Firstly hydrogen ions, which in the absence of enough oxygen start to cause acidosis within the muscles slowing down the athletes contraction rate.
Secondly inorganic phosphate which loves to bind with Calcium, now this would be fine if it wasn't for the fact that calcium plays a crucial role in the bodies ability to produce muscle contractions within the body.
This is usually where athletes start to cramp and get that heavy feeling in their legs. So by training at high intensity we can teach the body to deal with this accumulation of metabolic byproducts as well as become more efficient at processing/removing this build-up of hydrogen ions and inorganic phosphates (which a person wouldn't develop while performing below the lactate threshold or purely aerobically, as in a steady long distance run for instance).
Therefore, not only is HIIT (High intensity interval training) time efficient (sessions generally last no longer than 25-30 minutes), it can reduce detraining effects (transition of fast twitch muscle fibres to slow twitch muscle fibres), replicate game like energy production/requirements, increase Vo2max and lactate threshold (Anaerobic threshold). Importantly, it also helps train your body to remove and process metabolic by-products which will be the main limiting factor for athletes in game like scenarios.
Jereme Russell was an Intern and Coach with ESS from 2016-2017