CLA Does Not Improve Cardio, Endurance, or Power

CLA didn’t perform so well in the latest study. After an eight-week trial there was no difference in any performance markers.

Conjugated linoleic acid (CLA) has been a popular supplement for controling insulin and blood sugar from some time, but it has recently come under fire in the scientific community because of inconsistent results. Researchers recently performed a study published in the Journal of Strength and Conditioning Research to find the truth.

What Is CLA?

CLA is a type of fat found in the meat and dairy products of cows and sheep. It has been sold as a supplement for some time. The supposed benefits of CLA come from an improvement to insulin sensitivity. Insulin sensitivity means that your cells are more receptive to the effects of insulin. Since insulin modulates blood sugar and supports anabolism (muscle growth), it is important to athletes and non-athletes alike.

CLA is also proposed to enhance fat burning during cardio, reduce the waste products from exercise, and reduce the accumulation of acid resulting from exercise. All of these features modulate fatigue. As a result, CLA is taken by diabetics, bodybuilders, and many people in between as a way to improve health and boost the effects of exercise.

The problem is, CLA only seems to work on non-human animals. While there is evidence that milk can improve insulin sensitivity, much of the research on CLA itself in human beings is either inconclusive or mixed. It simply doesn’t seem to do any of these things it’s supposed to and for every study showing that it might, there is another showing that it might not.

One way to find out if CLA works is to test the effects, if any, it has on performance. As an ergogenic aid, CLA hasn’t been studied well, and results have been inconclusive. Because better insulin sensitivity means a greater ability to transport energy-yielding carbohydrate into muscle tissue, one could surmise that CLA should increase endurance performance.

Study Design

In today’s study, 33 participants performed six weeks of cardio at moderate intensity. They worked at their fatigue thresholds while supplementing with 8mL of CLA every day. They were also tested on muscular endurance via a timed sit up test, and power with a long jump test. Half of the participants were given a placebo instead of CLA to find the differences.

After the eight weeks, there was no difference whatsoever between the two groups. Cardio, muscular endurance, and power all remained unaffected by CLA supplementation. For the cardio, the researchers focused specifically on any possible increase in the intensity at which the participants could exercise and still be at their fatigue threshold, but there was none.

So, despite the increasing popularity of CLA, and its many purported benefits, there still doesn’t seem to be any great reason to take it. While some of the prior research on the other effects of CLA have been mixed, leaving room for possible benefits, this study on the ergogenic effects of CLA has come up with nothing. For now, don’t expect any miracles if you decide to try it out.


1. Joel Cramer, et. al., “Effects of six weeks of aerobic exercise combined with conjugated linoleic acid on the physical working capacity at fatigue threshold,Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000513

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