A truth, by definition, is a verified or indisputable fact. In the realm of fitness, accurate information about performance and nutritional supplements is crucial yet often overshadowed by widespread misconceptions. This article aims to dispel confusion by providing a scientific evaluation of nine popular supplements. We will explore the evidence behind each to determine whether their effects are genuinely beneficial or merely part of fitness folklore.

Scope of Practice and Quality of Evidence

It is beyond the scope of practice for health and exercise professionals to provide specific nutrition or supplement recommendations to clients. Alternatively, evaluating the scientific merit of performance and nutritional supplements and providing sound educational resources fall within the realm of your work with clients, and can serve to help them make informed decisions. The evidence related to nine common performance and nutritional supplements is presented here. How did we reach these conclusions? The final consensus (truth or myth) was based on whether sound theoretical rationale and supporting evidence exists for the efficacy and safety of the performance and/or nutritional supplement. 

1. Creatine

It has been suggested that creatine monohydrate is the most effective supplement available to fitness enthusiasts for improving high-intensity exercise performance and increasing muscle mass. Indeed, there is a mountain of scientific literature demonstrating that creatine supplementation increases skeletal muscle mass during exercise training. Moreover, the long-term safety of creatine monohydrate has been well-established.

Creatine is an essential substrate for the phosphagen energy system and is involved in adenosine triphosphate (ATP) regeneration during high-intensity exercise. As such, creatine supplementation has also been shown to result in an enhanced ability to match cellular ATP production and demand during high-intensity and repeated bouts of intense exercise.

There is also recent promising research showing that creatine supplementation may benefit brain health, as well.

Creatine supplementation can increase creatine storage in skeletal muscle with a loading phase (20 to 25 grams/day for five to seven days) followed by a maintenance dose of 3 to 5 grams/day.

Final consensus: Truth

2. Chronic Use of Antioxidants

Conventional wisdom suggests that antioxidant supplementation may improve exercise performance and enhance recovery by countering the increase in free radicals associated with exercise due to the long and well-established link between cell damage and free radicals. However, more contemporary research has questioned the effectiveness of the antioxidant supplementation strategy altogether. In the last decade, in fact, a growing body of research suggests that superfluous (i.e., excessive) doses of antioxidant supplements consumed to retard free radical production during exercise training contributes to increased muscle fatigue and delayed recovery. Moreover, it has also been reported that antioxidant supplementation with vitamin C hampers training-induced adaptations in endurance performance.

Collectively, these findings strongly infer that antioxidant supplementation hampers favorable exercise training adaptations and interferes with the recovery process. 

Final consensus: Myth

3. Caffeine

Caffeine is a natural stimulant found in coffee, tea and many nutritional supplements. Robust scientific evidence has demonstrated that caffeine ingestion serves as an effective ergogenic aid for both cardiorespiratory and muscular exercise performance. Caffeine ingested orally is quickly absorbed into the bloodstream and peaks within 30 to 60 minutes.

Caffeine mechanistically affects the central nervous system primarily by antagonism of adenosine receptors, which results in enhanced mood, reduced perception of pain and increased attention. At the skeletal muscle level, caffeine ingestion promotes enhanced sodium/potassium pump activity, greater calcium release from the sarcoplasmic reticulum, and increased fat oxidation/glycogen sparing.

Overall, it has been recommended that a caffeine dosage of approximately 3 to 6 mg/kg body weight ingested 30 to 60 minutes prior to exercise or during the middle and later stages of sports or activities with an accumulation of fatigue (i.e., long continuous and intermittent activities) will increase work capacity and time-to-exhaustion and reduce perceived effort during endurance exercise.

Final consensus: Truth

4. Carnitine

Carnitine is an ammonium compound produced endogenously by the liver and kidneys. It serves as a transporter of long-chain fatty acids into the mitochondria, where it is oxidized for energy production and thus plays a key role in the regulation of lipid metabolism. Accordingly, both scientists and sport nutritionists alike have entertained the notion that supplementation could increase the bioavailability of carnitine and enhance overall capacity for lipid metabolism. This theoretical scenario could have both weight-loss and endurance performance implications. In fact, one study demonstrated that 24 weeks of L-carnitine supplementation in men increased total muscle carnitine, enhanced lipid utilization (while sparing muscle glycogen) and elicited an 11% improvement in cycling work output.

Nevertheless, to date, the majority of research findings on carnitine supplementation suggests it does not significantly alter total muscle carnitine content, enhance lipid metabolism, improve exercise performance and/or elicit weight loss in individuals who have overweight or obesity. As such, there is little to no evidence to support the efficacy of carnitine as an ergogenic supplement.  

Final consensus: Myth

5. Glutamine

Glutamine is an amino acid that is used in the biosynthesis of proteins. Common dietary sources of glutamine include beef, chicken, fish, dairy products, eggs, beans and vegetables such as carrots and spinach. It was originally suggested that glutamine supplementation could stimulate protein synthesis and thereby promote enhanced muscular performance. Indeed, earlier research findings assessed the effects of supplemental whey protein with or without added glutamine and branched-chain amino acids on body mass, body composition and exercise performance for a 10-week period. The researchers observed that whey protein combined with glutamine and branched-chain amino acids, in addition to resistance exercise, elicited significant improvements in body composition and exercise performance. However, more recent research has found glutamine supplementation does not benefit muscular performance.

In summary, there is insufficient scientific evidence to support glutamine supplementation for increases in lean body mass and/or muscular performance.

Final consensus: Myth

6. Sodium Bicarbonate (aka Baking Soda)

Recovery from cellular acidosis is paramount for restoring the capacity to regenerate ATP from both the phosphagen system and glycolysis. Muscle-buffering capacity can be augmented by nutritional strategies. Indeed, alkalizing agents have been studied extensively for their potential for enhancing performance by attenuating the extent to which metabolic acidosis contributes to fatigue during high-intensity exercise performance.

One such alkalizing substance that has been found to improve recovery by increasing the muscle-buffering capacity is sodium bicarbonate. The mechanism by which sodium bicarbonate ingestion mediates an ergogenic effect is by promoting the removal of protons from the skeletal muscle milieu. Given the fact that increased concentrations of proton molecules within the muscle cell are detrimental to skeletal muscle performance, an increased rate of removal from the skeletal muscle environment will result in a more rapid recovery. This, in turn, will permit a better performance of subsequent high-intensity exercise bouts.

The main drawback to the use of sodium bicarbonate is that some individuals experience gastrointestinal distress with its ingestion. Accordingly, it is a good idea to first purposefully experiment with the sodium bicarbonate loading protocols to maximize the alkalizing effects and minimize the risk of potential symptoms. The recommended single-does protocol and timeframe for sodium bicarbonate ingestion is 0.3 grams/kg of body weight 60 to 180 minutes before exercising provides an optimal cost/benefit balance. Sodium bicarbonate can either be ingested in capsule form or in a flavored beverage such as water.

Final consensus: Truth

7. Arginine

Arginine is an amino acid that is used in the biosynthesis of proteins. In the body, arginine changes into the potent vasodilator nitric oxide (NO). Given that NO is known to promote vasodilation and enhance skeletal muscle blood flow, it has been suggested that arginine supplementation may increase exercise performance.

Indeed, some experimental research exists to support this line of reasoning. For example, one study involved giving arginine (or a placebo) to 35 resistance-trained males in a double-blind study. The researchers concluded that upper-body strength and lower-body power output were significantly increased after supplementation. Despite these encouraging findings, however, most of the other published scientific studies regarding arginine supplementation have not reported a beneficial ergogenic result. Therefore, caution is warranted with regards to the use of arginine to enhance exercise performance.

Final consensus: Myth

8. β-alanine

The amino acid β-alanine naturally occurs in foods such as fish and meat and is a precursor and rate-limiting molecule for synthesis of carnosine. Carnosine itself is found in skeletal muscle and has numerous important physiological functions, including the regulation of calcium, enzymes and pH levels. Given its potential mechanistic ergogenic benefits, β-alanine supplementation has been heavily studied and the results have been positive. A meta-analysis revealed that β-alanine supplementation positively impacted individuals performing high-intensity exercises lasting between 60 and 240 seconds.

In terms of the most efficacious dosage, 3 to 6 grams per day of β-alanine for four to 10 weeks has been recommended. Beyond that timeframe, a maintenance dosage of 1.2 grams per day of β-alanine has been suggested.

Final consensus: Truth

9. Post-exercise Carbohydrate Ingestion

Though carbohydrate is not a supplement, per se, it is often viewed as a performance enhancer when consumed after exercise. In fact, doing so is a classic nutritional recommendation for recreational enthusiasts and athletes alike. After prolonged and exhaustive endurance-related exercise, the most important factor determining the timeframe to recovery is muscle glycogen replenishment. It has been well established for quite some time that post-exercise carbohydrate ingestion is critical to the synthesis of muscle glycogen.

More recently, both the precise timing of carbohydrate ingestion and optimal carbohydrate dosage have become better understood. Post-exercise muscle glycogen replenishment occurs in two phases: a rapid rate that persists for 30 to 60 minutes after exercise cessation, and a considerably reduced rate (60 to 90%) in the time period afterward. There is also evidence for a dose-response relationship between post-exercise dosage of carbohydrate ingestion and the rate of muscle glycogen resynthesis. For example, research has shown that consuming 1.2 grams per kilogram per hour (grams/kg/hour) of carbohydrate increased muscle glycogen content 150% more than consuming 0.8 grams/kg/hour of carbohydrate. However, ingestion of 1.6 grams/kg/hour of carbohydrate provided no further increase in muscle glycogen content. Additionally, more frequent provision of this overall carbohydrate dosage interspersed in smaller doses over a few hours is more effective at replenishing muscle glycogen compared to one or two large doses ingested less regularly.

In summary, to optimize muscle glycogen repletion after prolonged and exhaustive endurance-related exercise, it has been recommended to ingest 1.2 grams/kg/hour of carbohydrate at 15- to 30-minute intervals immediately after exercise.

Final consensus: Truth

Conclusion

As a health and exercise professional, your aim should always be to provide your clients with evidence-based educational resources on the effectiveness of various performance and nutritional supplements. This will help make it possible for your clients to make informed decisions and fully understand how consuming these products will impact their health, performance and training. 

Expand Your Knowledge

Exercise and the Role of Supplements

While supplement companies often claim their products offer dramatic results with no downside, the truth is that there’s a lot of misinformation circulating about supplementation. This makes it critical to understand what the science says about the relationship between nutrition, supplementation, physical activity and exercise. This course explores what supplements are, how they’re regulated, and how to determine whether they’re right for you.