Ergogenic Aids – Should I or Shouldn’t I? (Part 2 of 2)

Reyna F

As noted in Part 1 of this two-part series: ergogenic aids are substances taken to enhance the production and use of energy during physical exertion and for the subsequent recovery in order to gain an advantage. They are considered dietary supplements.

In the United States, dietary supplements are regulated under the 1994 Dietary Supplement Health and Education Act (DSHEA), which establishes legal definitions and label guidelines. The act does not ensure safety, effectiveness or quality of dietary supplements. It is the responsibility of the consumer to understand and judge those attributes. So you have to ask yourself “Is it safe?” and "Is it effective?” And if you participate in events where you may be tested, “Is it legal?”

There are many products on the market and new ones are continually emerging. In Part 1, we left off with creatine.  Here are a few more products that athletes may think about using and information that will help you answer the risk/benefit questions.

Glutamine

Claims about Glutamine

This supplement supposedly increases immune function, as well as prevents overtraining syndrome.

Glutamine in Research

The effectiveness of athletes supplementing with glutamine is not well-established. Castell et al. examined glutamine supplementation on competitive distance runners and rowers during both training and competition. 72 subjects received a glutamine beverage and 79 ingested a placebo immediately after exercise, and 2 hours after exhaustive exercise. The number of athletes that reported not having infections was significantly higher in the glutamine group, than in the placebo.

Castell et al. performed another study, which contradicted the above results. Glutamine did not appear to have an effect on immune function following the completion of a marathon.

Rhode et al., in a randomized cross-over, placebo-controlled study, examined glutamine supplementation and its impact on immune cells when participating in repeated exercise bouts; 8 subjects participated in the study. Post exercise immune changes did not seem to be caused by a decrease in plasma glutamine concentrations.

Recommendations

While plasma glutamine concentration may decrease after intense exercise, which in turn may result in muscle depletion, a healthy diet can help maintain normal glutamine levels; this can be done by consuming adequate carbohydrates and calories daily. Some research does suggest that glutamine supplementation may reduce the incidence of respiratory infections in athletes. Yet further research is required to support this data.

Glycerol

Claims about Glycerol

Ingesting glycerol is believed to enhance aerobic power and endurance performance, as well as improve thermoregulation. The theory is that glycerol hyperhydration just before endurance exercise may enhance performance by increasing plasma volume, reducing core temperature and decreasing heat rate.

Glycerol in Research

Various studies have been conducted on glycerol supplementation, but much more is needed. Lyons et al. examined glycerol supplementation and the concept of glycerol hyperhydration, discovering that glycerol hyperhydration may be more effective than water hyperhydration when reducing the thermal stress that results from moderate exercise in high temperatures.

Motner et al. conducted a double-blind, crossover study that examined the effect of glycerol hyperhydration and carbohydrate oral replacement solution (ORS) on endurance performance and thermoregulation. Participants cycled in a neutral laboratory environment. Those who consumed glycerol had a significantly longer endurance time and lower heart rate.

Some studies, however, have not found a benefit from glycerol hyperhydation. Latzka et al. studied the effect of glycerol hyperhydration, water hyperhydration and euhydration on core temperature and sweat rate during exercise. In two different studies the same 8 participants consumed either 1.2 g of glycerol / kg/lean body mass, with 29.1 ml of water per kg/lean body mass or 29.1 ml of water per kg/lean body mass. Hyperhydration did not alter core temperature, skin temperature, heart rate or sweat rate, when comparing it with euhydration. No difference was noted between glycerol trial and water trial for these physiological responses. This suggests that glycerol hyperhydration was not more effective than euhydration or water hyperhydration. This research indicates that supplementing with glycerol promotes hyperhydration but does not have cardiovascular or thermoregulatory benefits.

Recommendations

As of now the research is ambiguous. Research indicates it may benefit athletes participating in endurance sports in hot, humid climates. Keep in mind the amount of fluid recommended to be consumed with glycerol can leave one feeling bloated and heavy. The main side effects of glycerol supplementation are nausea, bloating, headaches, dizziness and vomiting. Those with diabetes, kidney disorders or high blood pressure should not supplement with glycerol.

L-Carnitine

L-Carnitine Claims

L-Carnitine is thought to increase the utilization of fatty acids as fuel, as well as to increase endurance and decrease body fat.

Research

Research does not support L-Carnitine as an effective supplement.

Trappe et al. examined the effect of L-carnitine supplementation in swimmers. The purpose of the study was to determine if carnitine could improve swim times by decreasing the accumulation of lactic acid. Two male college varsity swimmers participated in the study. Regarding lactic acid built up, blood pH, or swim velocity, there were no differences between those supplementing with carnitine and those ingesting the placebo. This study indicated that carnitine did not improve performance.

Greig et al. evaluated the effect L-carnitine supplementation has on exercise capacity. While a small improvement was seen in these untrained participants supplementing with L-carnitine, heart rate was not significantly lower. From these results, it was deduced that carnitine supplementation was of little or no benefit as an ergogenic aid.

Recommendations

Research has found no benefits for supplementing L-carnitine as an ergogenic aid. It appears to be safe, yet there is concern that some L-carnitine supplements may be adulterated with D-carnitine, a toxic substance that can deplete carnitine and result in carnitine deficiency. Further Research on L-carnitine’s effectiveness is needed before any recommendations can be made.

Medium Chain Trigylcerides (MCTs)

Claims made about MCTS

MCTS are thought to increase energy, decrease body fat, spare muscle glycogen and prolong endurance.

Research

Limited research exists on MCTs as a supplement. Jeukendrup et al., examined the oxidation rate of oral MCTS feedings in eight atheltes during a three hour exercise session. Subjects consumed either MCTs, carbohydrate (CHO), a combination of MCT and CHO, or a placebo. MCTs were oxidized at higher rates when combined with CHO. Additionally, only a small amount of MCT can be tolerated by the GI tract. About 30 grams. This limits the contribution of MCT sot the total energy expenditure.

Jeukendrup et al., later examined the effects of taking 85 grams of MCTs rather than 30 grams. They did this to see if increasing the amount supplemented would enhance fat oxidation and improve performance during 2 hours of exercise. The subjects were assigned to the same groups as above. Those subjects that received only MCTS saw a decrease of performance compared to the placebo trial. This negative impact was attributed to GI distress.

Van Zyl et al., examined MCT + CHO supplementation on cyclists and fat oxidation. These endurance cyclists consumed a mixture that contained 86 g of MCT, and saw a small increase in fat oxidation as well as improved time trials. These results suggest a glycogen-sparing effect. GI distress was not reported.

Recommendations

While MCTs are a legal supplement, more research is needed to assure that MCT supplementation improves endurance. Even if they truly do enhance performance, GI distress has been a rampant side effect and limits their potential as an ergogenic aid of choice. Those supplementing with MCT and other fats must also be aware of the possible increased risk of cardiovascular disease.

Nitric Oxide

Claims

Supplementing with nitric oxide is thought to promote muscle fiber repair and improve the clearance of lactic acid. It is also said that nitric oxide supplement may increase blood flow which can help efficiently deliver nutrients to muscle, as well as increase adrenaline.

Research

Limited research exists in regards to nitric oxide as an ergogenic aid. Some reports have found nitric oxide to actually improve blood flow and exercise function, however none of these studies have proven the safety of nitric oxide. Evidence has yet to be uncovered that nitric oxide can increase muscle mass. Medline Plus claims that nitric oxide can be beneficial for recovery after surgery and for chest pains.

Recommendations

While nitric oxide supplementation is legal, due to limited research, it is not recommended. Serious side effects have also occurred. These include: diarrhea, bloating, allergies, aggravation of existing asthma and hypotension. Nitric oxide can also negatively interact with medications such as blood pressure medications, Viagra, xylitol and nitrate drugs.

Steroids

Claims

Steroids are said to enhance performance by increasing muscle protein synthesis and thus increasing lean muscle mass. Steroids have been found to be effective, but have dangerous adverse effects.

Recommendations

Due to adverse effects, steroids are illegal. Congress has classified them as a schedule III controlled substance. Use is absolutely prohibited by the IOC and NCAA.

Adverse effects – decrease in HDL cholesterol, elevated blood pressure, aggressive behavior, azospermia, virilization in women, and gynecomastia. Heart attack and suicide has also been associated

Whey Protein

Claims about Whey

Whey protein is said to have high biological value, provide greater muscle gains as well as greater nitrogen retention.

Research

Studies have shown that whey protein has helped nourish very-low-birth-weight infants, and aide in preventing metabolic acidosis. Whey protein has also shown to increase glutathione levels. Glutathione is an antioxidant and may play a key role in immune function.

Bounous et al., examined the effects of whey protein formula on HIV-seropositve individuals. The purpose was to see if whey protein influenced glutathione levels and helped increase body weight. Results showed an increase in both.

Recommendations

Although whey protein may enhance immune function through increasing glutathione levels, it does not seem to increase muscle mass. Those athletes who want to increase muscle mass should follow strategies demonstrated to increase lean tissue. Such strategies include engaging in resistance training and consuming enough protein and calories.

Whey protein supplementation is legal and allowed.

-Reyna F.
MS, RD, CSSD, CPT

Nutrition and Exercise Consulting
www.reynafranco.com/