Performance Enhancers: Categories C and D

The use of category C supplements for athletes isn't supported by scientific evidence. Still, their use isn't prohibited.
Performance Enhancers: Categories C and D

Last update: 11 February, 2019

Performance enhancers are divided into categories according to their scientific backing. Though their claims aren’t 100 percent verified, athletes can try them out. Of course, they should always do so under the guidance and supervision of an expert.

According to the Australian Institute of Sport, performance enhancers in category A are backed by evidence. Then, those in category B need further research. In other words, category B is for those whose efficacy might be provable. Their function was shown but not how it works.

Performance enhancers: category C

If an athlete decides to take them, they should know the potential risks (if any). What’s more, they should seek the help of a health expert to learn more about these products.

In addition, the producers from this category have to provide certain data to the consumers. For example, they have to specify the:

  • Recommended dose
  • Maximum dose
  • Results of taking too much

The best-known Category C products


Current studies suggest that it could help curb some symptoms linked to exercise. For example, pain and stiffness after doing exercise that causes extreme muscle tension.

Most of the studies on ribose have shown positive results in those with a specific ailment. For example, people suffering from heart failure or fibromyalgia. These subjects did indeed experience relief from fatigue and muscle pain.

Still, at this point, there’s no evidence that it would have the same effect on healthy people.

Performance enhancers

Taking too much ribose can trigger digestive issues. As such, look out for diarrhea, nausea, swelling, and pain in your abdominal area. If you feel any of these effects, you should stop taking it and consult with a doctor.


It’s a substance that’s present in the fluid surrounding your joints. Further, glucosamine may play a role in cartilage repair in the joints. What’s more, it may help maintain synovia.

Some may advise taking it with other things to boost its action. This often involves vitamin C and collagen. As such, the effects aren’t only the results of glucosamine.

Coenzyme Q10

Some studies suggest that it could increase resistance and prevent fatigue from impacting sports performance. Research may show that an oral dose of coenzyme Q10 (300 mg) improves physical performance. What’s more, it may help curb fatigue during trials.

The results show these benefits may occur after days of continuous effort. For example, the exertion that cyclists apply in races or athletes during competitions.

MCTs (Medium chain triglycerides)

MCTs have been available for clinical use for years. They’re intended for people with diabetes and who have difficulty absorbing fat. In recent years, people have begun to take it as a performance enhancer.

Cyclist flying by

Some studies show that it can make your endurance last longer when mixed with carbohydrates. Researchers gave that mix to cyclists racing 40 km, rolling at 60 percent of their maximum capacity. The theory is that MCTs lower the oxidation of muscle glycogen during exercise. As a result, they may help to maintain it.

“Try and fail, but never fail to try!” -Jared Leto-

Category D

Any supplement from this category is totally banned and may produce a positive doping test. Athletes, in general, are advised to avoid these products. These include stimulants (ephedrine, strychnine), prohormones (DHEA, androstenedione and its derivatives) and Beta2-adrenergic agonists.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Nagao, K., & Yanagita, T. (2010). Medium-chain fatty acids: Functional lipids for the prevention and treatment of the metabolic syndrome. Pharmacological Research.
  • Page, K. a, Williamson, A., Yu, N., Mcnay, E. C., Dzuira, J., Mccrimmon, R. J., & Sherwin, R. S. (2009). Medium-Chain Fatty Acids Improve Cognitive Function in Intensively Treated Type 1 Diabetic Patients and. Diabetes.
  • Pavelká, K., Gatterová, J., Olejarová, M., Machacek, S., Giacovelli, G., & Rovati, L. C. (2002). Glucosamine sulfate use and delay of progression of knee osteoarthritis: A 3-year, randomized, placebo-controlled, double-blind study. Archives of Internal Medicine.
  • Porter, D. A., Costill, D. L., Zachwieja, J. J., Fink, W. J., Wagner, E., & Folkers, K. (1995). The effect of oral coenzyme Q10 on the exercise tolerance of middle-aged, untrained men. International Journal of Sports Medicine.
  • Mizuno, K., Tanaka, M., Nozaki, S., Mizuma, H., Ataka, S., Tahara, T., … Watanabe, Y. (2008). Antifatigue effects of coenzyme Q10 during physical fatigue. Nutrition.
  • Kreider, R. B., Melton, C., Greenwood, M., Rasmussen, C., Lundberg, J., Earnest, C., & Almada, A. (2003). Effects of Oral D-Ribose Supplementation on Anaerobic Capacity and Selected Metabolic Markers in Healthy Males. International Journal of Sport Nutrition and Exercise Metabolism.
  • Kerksick, C., Rasmussen, C., Bowden, R., Leutholtz, B., Harvey, T., Earnest, C., … Kreider, R. (2005). Effects of ribose supplementation prior to and during intense exercise on anaerobic capacity and metabolic markers. International Journal of Sport Nutrition and Exercise Metabolism.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.