Adiponectin: The Magical Fat-Burning Hormone?
Whether you want to stay lean for your sport or just to look good, it's important to understand how the body burns fat. For athletes, it also helps to understand how fat is used to fuel activity. The greater your ability to mobilize and use fat to power your actions, the better your results will be in virtually every sport.
One important but little-known facet of fat utilization is a protein-based hormone called adiponectin. This substance is released from adipose tissues into the blood and, despite its relative obscurity, is one of the most abundant hormones in the blood. Adinopectin plays many roles, not the least of which is regulating sugar and fat metabolism. However, the process by which adiponectin is stimulated requires further research, which is why it was the subject of a recent study in the Journal of Strength and Conditioning.
In the study, the researchers compared two rowing protocols. They measured adiponectin both at rest and after exercise, before and after a four-week program. There were two groups, one of which did an interval program, and one that did a traditional program. The traditional program was steady rowing for 35 to forty minutes, and both programs were two days a week.
Ultimately, neither program elevated resting levels of adiponectin. However, the response of adiponectin to interval training increased after the four-week protocol, and it did not for the traditional program. VO2 peak also increased and body fat dropped. As a result, the researchers ultimately concluded that, unlike steady-state training, interval training would result in superior results when it comes to glucose sensitivity and fat burning.
But not so fast. If you look at the actual data, you see that over the four-week period, there were only slight differences in average power output, VO2 peak, and body fat measurements between the two groups. The only major difference was the increase in adiponectin. If adiponectin is associated with fat burning, you would expect the decrease in body fat percentage to be much higher in the interval group. However, the differences between the two groups were pretty minimal, even with matched calorie expenditure. Perhaps the length of the study just wasn’t sufficient.
Despite the conclusion of the researchers, this anomaly needs to be explained. When we look at what was actually studied, we see the researchers sampled the adiponectin after a max effort test. That means out of the two programs, the interval program was more similar to the blood sampling conditions. Sampling after a test that is more similar to one of the protocols creates a bias in the results, and in this case would favor the interval program. Theoretically, if the researchers had sampled the adiponectin after a test more similar to the traditional protocol, the results would be reversed, despite the same conditions otherwise.
So ultimately, when looking at the important results of this study, such as fat burned, you’ll see there was limited difference between the two protocols when matched for calorie burn. I will agree with the researchers on one thing: more research on adiponectin is needed.
1. Shing, Cecilia M, et. al., “Circulating Adiponectin Concentration and Body Composition Are Altered in Response to High-Intensity Interval Training,” Journal of Strength & Conditioning Research, 27:8 (2013)
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