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.
The results showed the relative total contribution of the energy systems as follows:
Graphed by distance, the aerobic/anaerobic contribution looks like this:
As expected, the shortest distance/duration event (200 m.) required the lowest relative aerobic contribution while the longest distance/duration event (1500 m.) required the greatest relative aerobic contribution. While this finding isn’t new, the extent and timing of aerobic contribution is remarkable since it occurs earlier and in higher percentages than commonly understood. For instance , the aerobic system appears to contribute nearly one-third of the total energy required in a 22-second 200 m. run and nearly half of the energy required in a 49-second 400 m. run. Based on the current study, the anaerobic and aerobic energy systems appear to contribute equally to single, max. effort runs at distances just beyond 400 m., somewhere between 50-75 seconds. Remember, this does not account for less-than-maximal efforts (where the aerobic contribution would be greater sooner) or repeated runs such as those used during interval training sessions (where the aerobic contribution would progressively increase and occur progressively sooner even in the shortest distances/durations). It also doesn’t account for the mid-run crossover to aerobic dominance which we’ll discuss below.
In support of their findings, Spencer and Gastin reference comparable studies with similar findings. For instance, regarding the current finding of 29% mean aerobic contribution to the 22-second 200 m. trials, Spencer and Gastin found this was similar to the finding of 28-40% mean aerobic contribution during 30 seconds of exhaustive cycling measured by Medbo and Tabata (1989), Withers et. al. (1991), and Medbo et. al. (1999). Spencer and Gastin’s finding of 43% mean aerobic contribution to 49-second, 400 m trials was similar to findings of 37-50% aerobic contribution in 49-57 seconds of exhaustive treadmill running measured by Medbo and Sejerssted (1995) and Nummela and Rusko (1995), and to 40% aerobic contribution to 45 seconds of maximal cycling found by Withers et. al (1991). Spencer and Gastin’s 800 meter findings, with 66% mean aerobic contribution in 113 seconds, compared favorably to Craig and Morgan (1998) and Hill (1999) and Spencer et. al. (1996) who reported 58–69% aerobic contribution during 116 –120 seconds of running. Lastly, Spencer and Gastin’s data regarding the 1,500 appeared similar to findings of Spencer et. al. (1996) and Hill (1999) who reported 75– 83% aerobic contribution for subelite 1500-m runners.
Crossover to Aerobic Dominance
During most exercise, there comes a time when energy supply from the aerobic system begins to exceed energy supply from the anaerobic system. This is known as the “crossover” point to aerobic dominance. We have explained in prior posts that this crossover is now thought to occur much earlier during exercise than previously understood (folks wrongly used to think it took several minutes or more). The Spencer and Gastin study supports this revised view as revealed by the following figure:
As seen in the figure, the actual crossover to aerobic dominance occurred between 15 and 30 seconds during the 400, 800, and 1500. In other words, within 30 seconds or less of maximal effort, the aerobic system became responsible for providing more energy than the anaerobic system. It may be important to note that this crossover to aerobic dominance occurs even in short events like the 400 m where a portion of the effort becomes dominantly aerobic despite the overall greater anaerobic contribution. This helps explain why poor aerobic conditioning can cause poor 400 m. performance and, likewise, why 400 m. repeats (or shorter) can have significant aerobic/endurance benefits. Again, it may also be useful to keep in mind that the aerobic crossover point in any distance, no matter how short, will occur progressively sooner and increase progressively faster when intervals are repeated and/or intensity declines.
Spencer and Gastin conclude:
[T]he relative contribution of the aerobic energy system is considerable and greater than has been traditionally accepted during 200-, 400-, 800-, and 1500-m running. The results demonstrate that the aerobic energy system is the predominant energy system by the 30-s time period during the 400-, 800-, and 1500-m running events.
Duffield and Dawson (2003)
In 2003, Rob Duffield and Brian Dawson evaluated the energy system contribution to single, maximal-effort 100, 200, 400, 800, 1500, and 3000 meter runs (See “Energy System Contribution in Track Running” (PDF)). Not content to rely on simulated race performances on a treadmill or mere data modeling, they conducted live tests on a 400 meter track. They used 66 trained track athletes (male and female) with experience ranging from club to national level. Each of the runners had a specialty distance and was tested only in that specialty distance. Energy system contribution was determined by measuring expired gases from the breath of the tested subjects while they ran (using a portable device by Cosmed) and by measuring blood lactate before and after the runs.
The results showed the relative total contribution of the energy systems as follows:
Graphed by distance, the aerobic/anaerobic contribution looks like this (note: we averaged the male and female #s):
Again, not surprisingly, Duffield and Dawson found that relative total aerobic contribution increased as event distance and duration increased. Relative aerobic contribution was the lowest in the 100 m run and greatest in the 3,000 m run. Similar to Spencer and Gastin, Duffield and Dawson found that the total energy production was approximately equal at a distance just over 400 m, or approximately 50 seconds of maximal effort. Also similar to Spencer and Gastin, Duffield and Dawson found that the crossover point to aerobic dominance occurred well before the one minute mark:
[D]uring the 1500m and 3000m events, the aerobic and anaerobic energy systems show a cross over in dominance between the respective systems by 200m (~30 sec). During the faster sprint endurance events, a cross over point occurs between the 200- and 400m mark (~40 – 55 sec)
Though the Duffield and Dawson crossover points appeared to occur slightly later than those measured in Spencer and Gastin, both groups confirm that this crossover occurs well-within the first minute of intense activity. Also, it makes sense that the crossover to aerobic dominance would occur sooner in the longer distances since presumably the longer distance runners began their runs at slightly lower relative intensities than the sprinters. At lower relative intensities, the aerobic crossover point is bound to occur earlier. Finally, at the risk of belaboring this point, repeating these max. efforts as intervals and/or any further reductions in intensity would elicit a crossover to aerobic dominance far sooner and at a greater rate.
Dawson and Duffield conclude by stating humbly:
[T]hese studies highlight and confirm previous research outlining both the significance of and speed at which the aerobic energy system becomes involved in maximal exercise between 11 sec and 10 min.
Taken together, we think the Spencer and Gastin study along with the Duffield and Dawson study lend great explanatory power to lower-volume, higher-intensity training protocols for endurance athletes. Whereas short, hard efforts were once considered predominantly anaerobic and therefore unsuitable for the aerobic training needs of serious endurance athletes, we are learning that this view is mistaken. Instead, short-hard efforts (whether or not repeated, but especially when repeated) call upon the aerobic system, not the anaerobic system, as the primary source of energy. Because they engage the aerobic system directly, early, and predominantly, such efforts lead to significant aerobic adaptations and thus improve endurance.
We’ve added both of these studies to our Research Library as:
- Spencer, MR and Gastin, PB, Energy system contribution during 200- to 1500-m running in highly trained athletes, Med Sci Sports Exerc. 2001 Jan;33(1):157-62. [Abstract] [Full PDF]
- Duffield, RJ and Dawson, B, Energy system contribution in track running, New Studies in Athletics,18:4; 47-56, 2003. [Full PDF]
Note: It appears the Duffield and Dawson study was later republished as a series of separate papers, each covering two of the six distances studied:
- Duffield, RJ and Dawson, B, Energy system contribution to 100-m and 200-m track running events, J Sci Med Sport. 2004 Sep;7(3):302-13. [Abstract]
- Duffield, RJ and Dawson, B, Energy system contribution to 400-metre and 800-metre track running, J Sports Sci. 2005 Mar;23(3):299-307. [Abstract]
- Duffield, RJ and Dawson, B, Energy system contribution to 1500- and 3000-metre track running. J Sports Sci. 2005 Oct;23(10):993-1002. [Abstract]
We have also added to our Research Library the following comparable studies cited by Spencer and Gastin and mentioned in our summary above:
- Craig I.S. and Morgan, D.G. Relationship between 800-m running performance and accumulated oxygen deficit in middle-distance runners. Med. Sci. Sports Exerc. 30):1631–1636,1998. [Abstract]
- Hill, D. W., Energy system contribution in middle-distance running events, J. Sports Sci. 17:477– 483, 1999. [Abstract]
- Medbo, J., Gramvik, P., and Jebens, E., Aerobic and anaerobic energy release during 10 and 30 s bicycle sprints. Acta Kinesiol. Univ. Tartuensis 4:122–146, 1999.
- Medbo, J., and Sejersted, O., Acid-base and electrolyte balance after exhausting exercise in endurance-trained and sprint-trained subjects. Acta Physiol. Scand. 125:97–109, 1985. [Abstract]
- Medbo, J., and I. Tabata. Relative importance of aerobic and anaerobic energy release during short-lasting exhausting bicycle exercise. J. Appl. Physiol. 67:1881–1886, 1989. [Abstract]
- Nummela, A., and Rusko, H., Time course of anaerobic and aerobic energy expenditure during short term exhaustive running in athletes. Int. J. Sports Med. 16:522–527, 199. [Abstract]
- Spencer, M.R., Gastin, P.B., and Payne, W.R., Energy system contribution during 400 to 1500 meters running. New Studies Athl.11(4):59 – 65, 1996.
- Withers, RT, Sherman, WM, Clarket, DG, et. al., Muscle metabolism during 30, 60, and 90 s of maximal cycling on an air-braked ergometer. Eur. J. Appl. Physiol. 63:354 –362, 1991. [Abstract]