As a high school swimmer, coaches would constantly refer to the need to build an 'aerobic base' for future swimming success in college. As a coach, I heard the phrase shift from 'base' to 'capacity'. The clear sustained implication that copious amounts of 'work' were a pre-requisite to reap long-term benefits that may or may not be correlated. Only now do I understand that the aerobic capacity'is a function both of cardiorespiratory performance and the maximum ability to remove and utilize oxygen from circulating blood.'
Aerobic Capacity is Different from Efficiency
Capacity is not efficiency. Two cars fuel up. One has a 20-gallon tank and gets 15 MPG. The other has a 15-gallon tank and gets 30 MPG. If the race is 400 miles long, one car won't make it without a pit stop.
The obvious gain then is to build a larger tank while maintaining MPG. But what if the larger tank isn't needed for a shorter trip and constant braking in the city? Instead, fuel delivery should be more efficient from priming the engine on start, conserving fuel with smooth accelerations, etc. Adapt and plan workouts to best challenge oxygen utilization in training so your 'engine' suits your needs.
Aerobic Energy System
High-Intensity Interval Training (HIIT) is not a new phenomenon and certainly not a fad. HIIT is a catch-all 'coach speak' phrase to get athletes moving toward a goal. This is how we break down aerobic energy systems (first six rows) in training and the contributions all intervals have to the process.
Its inception is credited to Jon Urbanachek and Jonty Skinner. Its innovation to Jim Steen. Its understanding and evolution to the Auburn Kinesiology department. And its ongoing tinkering to the best coach ever.