Previously we’ve compiled evidence that high-intensity athletic efforts are significantly more aerobic than once thought. Such evidence reveals that high-intensity efforts as short as six seconds can become significantly aerobic, and single max. efforts lasting less than one minute can be predominantly aerobic (i.e. more than 50% of the ATP is supplied by the aerobic system). While the evidence demonstrates a significant, progressive shift towards greater aerobic contribution during interval repeats, it also reveals the crossover from dominant anaerobic to dominant aerobic energy production can occur within the first 30 seconds of intense activity (correcting the old misconception that aerobic energy dominance requires several minutes or more and/or sub-maximal intensity). Together, this body of evidence suggests that short-duration, high-intensity training can deliver tremendous aerobic and endurance benefits because the training itself can be highly aerobic.
Adding to the evidence, we highlight below two separate studies that evaluated energy system contribution to maximal effort running of various short and middle distances. Two separate research groups conducted these studies independently and arrived at remarkably similar results.
Spencer and Gastin (2001)
In 2001, Matt Spencer and Paul Gastin analyzed energy system contribution to single, maximal-effort 200, 400, 800, and 1500 meter runs (See “Energy System Contribution During 200- to 1500-m Running in Highly Trained Athletes” (PDF)). They used 20 highly trained males, all of whom had competed at state, national, and/or international competition, each of whom were specialists in one of the distances to be tested. Each specialist was tested in their specialty distance only. The tests were conducted on a treadmill, set at 1% gradient to simulate the supposed energy cost of outdoor running. Energy system contribution was determined by measuring expired gases from the breath of the tested subjects while they ran.