The optimal interval duration for VO2 max training is determined by maximizing mitochondrial function and ensuring the energy system can oxidize both glucose and fatty acids through mitochondria with oxygen.

“because what we're really looking at here is how the maximum but but we want to make sure we don't make the interval too small that we're getting we're quote unquote cheating and using pure glycolytic power which obviously has its benefits but won't necessarily increase presumably at some level mitochondrial function and mitochondrial throughput I mean we really because we're so focused on V2 Max here we want to make sure we're increasing both we're increasing an energy system that is flexible enough to oxidize both glucose and fatty acid through the mitochondria and therefore with oxygen”