In supplements part 1. The importance of proper training and nutrition as the most important aspect of any muscle building, strength or nutrition plan, was discussed. Supplements come way down the list of priorities.
Section 2 provided an analysis of the scientific literature regarding supplements aimed at building muscle. This section will take a closer look at supplements aimed to help improve exercise performance.
Several nutritional supplements have been proposed to enhance exercise performance. This section will place emphasis upon results that directly measure some attribute of performance.
Again each supplement has been put into categories by The International Society of Sports Nutrition (ISSN) based upon the available scientific literature and categorised into three categories based upon the quality and quantity of scientific support available.
Strong Evidence to Support Efficacy and Apparently Safe, Limited or Mixed Evidence to Support Efficacy, Little to No Evidence to Support Efficacy and/or Safety.
Performance Enhancing Supplements With Strong Evidence to Support Efficiency & Apparently Safe.
ß-alanine, a non-essential amino acid, has ergogenic potential based on its role in carnosine synthesis. Carnosine is a dipeptide comprised of the amino acids, histidine and ß-alanine, that naturally occur in large amounts in skeletal muscles. Carnosine is believed to be one of the primary muscle-buffering substances available in skeletal muscle.
Studies have demonstrated that taking 4 to 6 g of ß-alanine orally, in divided doses, over a 28-day period is effective in increasing carnosine levels, while more recent studies have demonstrated increased carnosine and efficacy up to 12 g per day.
According to the ISSN position statement, evaluating the existing body of ß-alanine research suggests improvements in exercise performance with more pronounced effects on activities lasting one to 4 min; improvements in neuromuscular fatigue, particularly in older subjects, and lastly; potential benefits in tactical personnel.
Other studies have shown that ß-alanine supplementation can increase the number of repetitions one can do, increase lean body mass, increase knee extension torque, and increase training volume. One study also showed that adding ß-alanine to creatine improves performance over creatine alone. While it appears that ß-alanine supplementation can improve performance, other studies have failed to demonstrate a performance benefit.
Caffeine is a naturally derived stimulant found in many nutritional supplements typically as guarana, bissey nut, or kola. Caffeine can also be found in coffee, tea, soft drinks, energy drinks, and chocolate. Caffeine has also been shown to be an effective ergogenic aid for aerobic and anaerobic exercise with a documented ability to increase energy expenditure and promote weight loss.
Some concern has been expressed that ingestion of caffeine prior to exercise may contribute to dehydration, although several studies have not supported this concern. Caffeine, from anhydrous and coffee sources are both equally ergogenic. Caffeine doses above 9 mg/kg can result in urinary caffeine levels that surpass the doping threshold for many sport organizations. In summary, consistent scientific evidence is available to indicate that caffeine operates as an ergogenic aid in several sporting situations.
Sodium bicarbonate (baking soda)
During high intensity exercise, acid (H+) and carbon dioxide (CO2) accumulate in the muscle and blood. The bicarbonate system is the primary means the body rids itself of the acidity and CO2 via their conversion to bicarbonate prior to subsequent removal in the lungs.
Bicarbonate loading (e.g., 0.3 g per kg taken 60–90 min prior to exercise or 5 g taken two times per day for 5 days) as sodium bicarbonate has been shown to be an effective way to buffer acidity during high intensity exercise lasting one to 3 min in duration.
It is important to highlight that a common complaint surrounding the ingestion of sodium bicarbonate is gastrointestinal distress, thus athletes should experiment with its use prior to performance to evaluate tolerance.
Limited or mixed evidence to support efficacy
Branched chain amino acids (BCAA)
Ingestion of BCAA (e.g., 6–10 g per hour) with sports drinks during prolonged exercise has long been suggested to improve psychological perception of fatigue (i.e., central fatigue).
Although a strong rationale and data exist to support an ergogenic outcome, mixed outcomes currently prevail as some studies have failed to report an ergogenic impact of BCAAs.
More research is needed to fully determine the ergogenic impact, if any, of BCAAs.
Essential amino acids (EAA)
EAA’s are made up from- Leucine, Lysine, Histidine, Tryptophan, Valine, Phenylalanine, Isoleucine, Methionine:
Research exploring the impact of essential amino acids with various forms of exercise has exploded. To date, it is well accepted that ingestion of at least 2 g of the essential amino acid, leucine, is required to stimulate cellular mechanisms controlling muscle hypertrophy and that ingestion of 6–12 g of a complete essential amino acid mixture is needed to maximize muscle protein synthesis. However, their impact on performance remains largely unexplored.
While sound theoretical rationale exists and multiple acute study designs provide supportive evidence, it is currently unclear whether following this strategy would lead to greater training adaptations and/or whether EAA supplementation would be better than simply ingesting carbohydrate and a quality protein following exercise. Moreover, very little research is available that has examined the ability of EAAs to impact exercise performance.
For these reasons, many authors and review articles have encouraged the prioritization of intact protein sources over ingestion of free form amino acids to promote accretion of fat-free mass, but as mentioned, the impact of this recommendation on performance changes remains undetermined.
L-Citrulline is an amino acid. It is turned into L-arginine in the kidneys after supplementation, which means L-citrulline supplementation is a more effective method of increasing L-arginine levels in the body than L-arginine supplementation. Oral citrulline supplementation has been shown to be more effective in increasing arginine and activation of nitric oxide synthase (NOS) as well as various biomarkers of nitric oxide.
The role of malate in combination with citrulline is largely undetermined. Since malate is an important tricarboxylic acid cycle intermediate, this could possibly account for improvements in muscle function. Therefore, it is presently unclear whether these benefits can be solely attributed to citrulline, as well as what role citrulline may play in aerobic and anaerobic performance.
Operating under the same theoretical framework as glutamine, interest in supplementing with L-alanyl-L-glutamine has increased in recent years. The ingredient has two parts: L-alanine and L-glutamine, both of which are amino acids that are mainstays in the transamination processes involving amino acids. Alanylglutamine is sometimes supplemented before prolonged physical exercise to enhance electrolyte absorption and improve endurance. More research is needed to determine if it influences performance.
β-hydroxy β-methylbutyrate (HMB)
HMB is an active metabolite of Leucine that reduces muscle protein breakdown. It appears to have an anti-catabolic role for muscle. For several years, HMB has received interest for its ability to enhance training adaptations and performance while also delaying or preventing muscle damage.
Differences in training regimens (intensities), randomization, and supervision in initial studies may have contributed to mixed results. HMB appears to have the greatest effects on performance when training intensity is maximized.
A systematic review by Silva and investigators concluded that the free acid form of HMB may improve muscle and strength and attenuate muscle damage when combined with heavy resistance training but stated that more research is needed before definitive conclusions can be determined.
Nitrate supplementation has received much attention due to their effects on vasodilation, blood pressure, improved work efficiency, modulation of force production, and reduced phosphocreatine degradation all of which can potentially improve sports performance.
Nitrate supplementation is most commonly consumed two to 3 h prior to exercise as beetroot juice or sodium nitrate and is prescribed in both absolute and relative amounts ranging from 300 to 600 mg or 0.1 mmol per kilogram of body mass per day, respectively.
Dietary nitrates have a health benefit in some, but not all populations.
There has been research which has shown that daily consumption of beetroot juice (~ 320–640 mg nitrate/d) significantly decreased resting systolic blood pressure in older adults by approximately 6 mmHg.
Nitrate supplementation (560 mg – 700 mg nitrate) significantly increased blood flow to working muscle and exercise time in older adults with peripheral artery disease as well as significantly improved endothelial function via increased flow-mediated dilation and blood flow velocity in older adults with risk factors of cardiovascular disease.
Collectively, these results indicate that nitrate supplementation may improve aerobic exercise performance and cardiovascular health in some populations.
Taurine is an amino acid found in high abundance in human skeletal muscle derived from cysteine metabolism that plays a role in a wide variety of physiological functions. Studies have indicated that training status (higher in trained vs. untrained muscle, and fibre type (higher in type I vs. type II, impact the amount of taurine found in muscle. It has been reported in some but not all studies that taurine may improve exercise performance and mitigate recovery from damaging and stressful exercise.
Studies have supported the ability of taurine to function in an anti-oxidative role, which may promote an improved cellular environment to tolerate exercise stress. While more research continues to be published involving taurine, the consensus of these outcomes continues to be mixed regarding taurine’s potential to enhance physical performance.
Quercetin is a flavonoid commonly found in fruits, vegetables and flowers, and is known for having some health benefits with therapeutic use. In addition, quercetin has been purported in both animal and human models to improve endurance performance.
more research needs to be completed to better identify what situations may exist that support quercetin’s ability to impact exercise performance.
Arachidonic acid (ARA)The body relies on ARA to promote and help resolve inflammation. ARA is a long-chain polyunsaturated fatty acid that resides within the phospholipid bi-layer of cell membranes at concentrations that are dependent upon dietary intake. ARA is not found in high amounts in the typical western diet.
However, as little as 1.5 g per day of supplementation over a 50-day period has been shown to increase tissue cell membrane stores of ARA. In skeletal muscle, there is evidence that ARA drives some of the inflammatory response to strength training via enhanced prostaglandin signalling.
More human studies testing different doses of ARA supplementation are needed to fully examine its safety and potential efficacy as a performance enhancing or muscle building aid.
From a safety perspective and due to ARA being a known pro-inflammatory fatty acid, use of ARA may be contraindicated in populations that have compromised inflammatory health (i.e., inflammatory bowel syndrome, Chron’s disease, etc.).
Ingesting glycerol with water has been reported to increase fluid retention and maintain hydration status. Theoretically, this should help athletes prevent dehydration and improve thermoregulatory and cardiovascular changes. Although studies indicate that glycerol can significantly enhance body fluid, results are mixed on whether it can improve exercise capacity.
Variable outcomes surrounding glycerol continue to undermine its potential and the ability to offer a recommendation for its use.
Post -Exercise Carbohydrate & Protein
Ingesting carbohydrate with protein following exercise has been a popular strategy to heighten adaptations seen as part of a resistance training program. The rationale behind this strategy centres upon providing an energy source to stimulate MPS via key signal transduction pathways. Additionally, carbohydrate intake will impact insulin status which could promote MPS, limit protein breakdown or both. Furthermore, combining carbohydrate with protein can heighten glycogen resynthesis rates, particularly when carbohydrate intake is not optimal and can improve muscle damage responses after exhaustive exercise.
A key to consider when interpreting findings from this literature is the amount of protein, essential amino acids or leucine being delivered by the protein source. In the last few years many studies have agreed that post workout supplementation is vital to recovery and training adaptations. However, the need for adding carbohydrate to protein to maximize hypertrophic adaptations continues to be questioned.
Little to no evidence to support efficacy and/or safety
Arginine is known as a conditionally essential amino acid which has been linked with the ability to increase exercise performance, increase growth hormone production, support immune function, increase training tolerance and promote accretion of fat-free mass. Several studies have sought to examine the ergogenic potential of arginine using both endurance and resistance exercise models with largely mixed results.
As it stands, most of the published literature that has examined the ability of arginine to operate in an ergogenic fashion has failed to report positive outcomes. While more research is certainly indicated, consumers should exercise caution when using arginine to enhance exercise performance.
Carnitine is produced endogenously by the liver and kidneys and plays a pivotal role in lipid metabolism. Consequently, many are led to believe that carnitine ingestion will increase the concentration of endogenous carnitine, thereby increasing lipid metabolism and decrease adipose reserves. To date, most of the data continues to suggest that carnitine supplementation does not markedly affect muscle carnitine content, fat metabolism, exercise performance, or weight loss in overweight, obese or trained subjects.
Of note, studies have suggested that co-ingesting carnitine with carbohydrate can lead to significant increases in intramuscular carnitine. Later, Wall and colleagues reported that endurance exercise performance was improved and improvements in fuel selection appeared to occur.
While interesting, more research is needed regarding changes in performance before further recommendations can be made.
As outlined in section 2, a strong theoretical framework exists for glutamine’s ability to help an individual tolerate stress, particularly when relying on animal studies.
A close examination into the available human research on glutamine makes it more challenging to characterize glutamine’s potential. Theoretically, glutamine supplementation during training should enhance gains in strength and muscle mass, but evidence in this respect has not been consistent.
Glutamine supplementation has been shown to improve glycogen stores which could go on to impact certain types of exercise performance and two recent studies suggest that glutamine provision may help support recovery from damaging resistance exercise. In this respect,
Street and colleagues concluded that adding glutamine (0.3 g/kg) to a carbohydrate drink significantly improved muscle soreness and force production, but did not impact changes in creatine kinase, when compared to carbohydrate only ingestion. A similar outcome was found by Legault and colleagues who reported that glutamine supplementation significantly lowered perceived soreness levels and led to improved recovery of force production after a damaging bout of eccentric muscle contractions.
From an ergogenic perspective, limited research is available, but Antonio et al reported that 0.3 g/kg glutamine ingestion did not impact the number of repetitions completed with the leg press or bench press exercises. Consequently, minimal research is available to support glutamine’s ability to operate as an ergogenic aid.
Inosine is a building block for DNA and RNA that is found in muscle. Inosine possesses important roles that may enhance training and/or exercise performance. Although there is some theoretical rationale, available studies indicate that inosine supplementation has no apparent effect on aerobic or anaerobic exercise performance.
Medium chain triglycerides
Medium chain triglycerides (MCT’s) are shorter chain fatty acids known to readily enter the mitochondria and be converted to energy through beta-oxidation.
Studies are mixed as to whether MCT’s are ergogenic and can serve as an effective source of fat during exercise. It does not appear likely that MCT favourably impacts acute exercise performance and no evidence exists that training adaptations may be positively impacted either, while multiple studies have reported that MCT ingestion may cause gastrointestinal upset and decrease exercise performance.
Ribose is a 5-carbon carbohydrate that is involved in the synthesis of adenosine triphosphate (ATP) and other adenine nucleotides. Clinical studies have shown that ribose supplementation can increase exercise capacity in heart patients leading to the development of theories that it can operate as ergogenic aid for athletes. Of the available research, most fail to show an ergogenic value for ribose supplementation on exercise capacity in healthy untrained or trained population.
As it stands, clinical findings provide support while studies in healthy, trained populations generally fail to report a positive outcome for ribose supplementation. Healthy individuals with lower fitness levels may afford some benefit.
In part 3 lets take a look at the evidence behind supplements aimed to help performance. Which supplements have strong evidence behind them and which ones have limited or weak evidence.
Jamie Miller- Personal Trainer
UK Fitness Personal Training
FITNESS, NUTRITION & PERSONAL TRAINING