CrossFit South Rockland

Tuesday, August 2, 2011

Revised Energy Systems Thinking Via The 200 Meter Freestyle

Revised Energy Systems Thinking Via The 200 Meter Freestyle
June 27, 2011 By Neil 1 Comment

Picking up on our theme that common understanding of energy systems training requires revision (see here, here, here and here), we just noticed this study on energy systems contribution to a single, max. effort 200 meter freestyle swim:

Figueiredo P, Zamparo P, Sousa A, Vilas-Boas JP, Fernandes RJ., “An energy balance of the 200 m front crawl race.” Eur J Appl Physiol. 2011 May;111(5):767-77. Epub 2010 Oct 27.

It supports our prior conclusion that short, intense efforts are significantly more aerobic than once thought. Though we don’t have access to the full paper, we were able to glean the following picture of energy systems contribution from the abstract.

Ten international swimmers performed a 200 meter freestyle at maximal effort. During the first length of the swim (in a 50m pool), the aerobic system contributed 44.6% of the energy produced. During the second length, 73.2%. Aerobic contribution peaked during the third length at 83.3%, and the final length came in at 66%. The total mean aerobic contribution throughout the entire swim was 65.9%. The total mean aerobic contribution during the last 3 lengths was 74.1%. Here is what these numbers look like graphically:

Adapted from Figueiredo 2011

Adapted from Figueiredo 2011

No doubt about it, the 200 freestyle appears highly aerobic. But how can this be? After all, the 200 free is a relatively short race (<2 minutes) and common models don’t predict aerobic system dominance until only after two to four minutes of effort. So what gives here?

Well, it appears we need to rethink common understanding of energy systems contribution to high-intensity efforts. This study demonstrated that the aerobic system contributes far more and far earlier than commonly assumed. Specifically, the aerobic system contributed virtually equal energy as the anaerobic system during the first 30 seconds of the swim. By the second length, well before the one minute mark, the aerobic system became dominant and remained dominant throughout the remaining sub-two-minute effort.

Some may be inclined to argue that the 200 free is a middle-distance event and therefore it begins with and sustains a lower-intensity effort throughout its duration (thus more likely to engage the aerobic system). On this basis, it would seem that a shorter race at a higher intensity would surely elicit less aerobic contribution. However, this is simply not supported by the research.

Studies by Stevens et. al. (1986), Granier et. al. (1995), Bogdanis et. al. (1996), Trump et. al. (1996), and Parolin et. al. (1999) in our Research Library (as well as other we have yet to review), all point to significant and in some cases dominant aerobic system contribution to just 30-seconds of maximal effort.

Further, Bogdanis et. al. (1996), Trump et. al. (1996), and Parolin et. al. (1999) confirm that there is a progressive shift to even greater aerobic energy metabolism when multiple intervals are performed.

Applied to the 200 freestyle in the current study, these prior studies not only support the findings, but they predict that any additional 200 meter repeats conducted in the same session would have reflected an even higher percentage of aerobic system contribution. According to the prior studies, this likely holds true for swims of even shorter distance and duration.

The broader implications, of course, are fairly straightforward. In a single, maximal sub-two-minute effort such as a race, aerobic system activation occurs earlier and at higher levels than previously assumed. For training purposes, this suggests that short-duration, high-intensity repeats are also way more aerobic than previously assumed. This has tremendous explanatory power for low-volume, high-intensity endurance training protocols.

According to this growing body of evidence, it appears low-volume, high-intensity training may enhance aerobic endurance at least partly because such training calls upon the aerobic system directly in very high percentages and under extremely heavy duress. It makes sense that under these circumstances the aerobic system would respond and adapt, resulting in greater endurance. Exactly how this happens is a question for another day. But assuming this general picture is accurate, it may be time to revise common thinking about energy systems training and endurance.

We’ll be exploring this concept further in the future. For now, we have added the study citation and abstract link to our Research Library.

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