Sports nutrition in natural bodybuilding (scientific review)

Nutritional Supplements 

When preparing for a competition, bodybuilders focus on the three most important aspects: strength and cardio training, and diet. However, some athletes also take various supplements to achieve better results. Federations advocating “natural” bodybuilding, as a rule, have quite extensive lists of prohibited substances, in this review we will consider only legal supplements. In addition, we will not consider protein supplements, since the basic rules for their intake coincide with the rules for taking protein contained in traditional food. Nevertheless, interested readers can read the works devoted to the intake of protein supplements.

Creatine

Creatine Monohydrate is considered the most ergogenic supplement not on the banned lists. Intake of creatine monohydrate in healthy adults does not affect liver and kidney function in any way. Numerous studies have documented significant increases in muscle mass and strength from creatine monohydrate supplementation during strength training programs. Many studies have documented an increase in muscle mass of 1–2 kg after taking a creatine supplement at 20 g / day for 4–28 days… It is noted, however, that the importance of the creatine loading phase is not so obvious. The intake of creatine in the amount of 20 g per day leads to an increase in the total level of creatine in the muscles by about 20%, in the future, this level can be maintained with a daily intake of 2 g of creatine for 30 days. At the same time, taking 3 g / day of creatine supplementation for 28 days also resulted in a 20% increase in muscle creatine levels. Thus, the “download” phase is not required.

Recently, alternative forms of creatine have begun to emerge, such as creatine ethyl acetate (CEE) as well as buffered forms of creatine (KA). Manufacturers position them as superior in quality to traditional creatine monohydrate (CM). However, these claims are not supported by real research. Tallon and Child found that CEE and KA are more susceptible to destruction in the human stomach than CM. In addition, recent studies have shown that the intake of CA and CEE for 28-42 days did not lead to a greater increase in the level of creatine in muscle tissue compared with CM. Thus, CM is arguably the most effective form of creatine.

Beta Alanine

Beta-alanine supplementation is becoming increasingly popular among bodybuilders. Once it enters the bloodstream, beta-alanine is absorbed by muscle tissue, where it is involved in the synthesis of carnosine, a dipeptide that plays an important role in anaerobic exercise such as sprinting or lifting weights. The intake of BA in the amount of 6.4 g daily for 4 weeks increases the level of carnosine by 64%. In addition, BA intake for 4-10 weeks can improve performance in knee extension exercises, have a positive effect on endurance indicators when performing high-intensity cardio exercises [144-148], and improve muscle endurance in strength exercises, provide an additional increase in muscle mass up to 1 kg, significantly reduce the subjective feeling of fatigue.

Co-administration of beta-alanine and creatine monohydrate (CM) can improve performance in high-intensity endurance exercise, as well as provide greater gains in lean body mass and reduction in body fat than the single intake of creatine monohydrate. However, not all studies have reported a positive effect of beta-alanine supplementation. To resolve the existing controversy, Hobson and colleagues conducted a meta-analysis of 15 studies, in the course of which it was found that beta-alanine supplementation can significantly increase power and athletic performance during exercise durations of 60-240 s (effect size – 0.665) and> 240 s (effect size – 0.368).

The long-term safety of BA administration has only been partially investigated. At the moment, the only documented side effect of BA intake is the symptoms of paresthesia, which can occur with the use of large doses; however, symptoms can be alleviated by reducing the daily amount of supplement taken. In cats, adding 5% BA to drinking water for 20 weeks resulted in decreased taurine levels and negatively affected the brain. It should be noted that taurine is an essential amino acid for cats, but not for humans, and it remains unclear what consequences long-term intake of beta-alanine in a similar dosage can cause in humans… So, BA intake is able to improve athletic performance, positively influence the growth of lean body mass, and is relatively safe in the short term. However, more research is needed to establish the long-term safety of BA in humans.

Beta Hydroxy Beta Methyl Butyrate (HMB)

Beta-hydroxy-beta-methylbutyrate (HMB) is a leucine metabolite that can stimulate muscle protein synthesis and slow down catabolism. The safety of HMB intake is currently widely studied, while there was no negative effect on liver, kidney, cholesterol, white blood cells, hemoglobin, and plasma glucose levels. Also, two meta-analyzes carried out have confirmed that the use of HMB is safe and does not cause any significant side effects. Taking HMB can lower blood pressure , LDL- cholesterol levels, especially in people with high blood cholesterol levels.

Reception of HMB is especially effective in people with a high level of catabolism (elderly people, people with chronic diseases, etc.). However, the effectiveness of HMB supplementation in trained individuals on a complete diet is assessed differently in different studies. Such discrepancies may be due to poorly planned training data collection, small samples, etc. Nevertheless, in general, the use of HMB can be considered effective in the long term, including for bodybuilders during high-intensity strength training… There is a hypothesis that taking HMB during a period of increased catabolism (for example, during an energy-deficient diet) may help maintain lean body mass, but this assumption has not yet been confirmed by long-term studies. Thus, additional research is required on this issue.

Branched chain amino acids

Branched chain amino acids (BCAAs) account for approximately 14-18% of the total amino acid mass in human muscle tissue. BCAAs are currently one of the most popular dietary supplements among bodybuilders. The most interesting in this regard is leucine, since there is evidence that taking leucine can stimulate muscle protein synthesis to the same extent as taking all other amino acids simultaneously. However, taking leucine can deplete valine and isoleucine stores; thus, the most rational approach is to take all three of these amino acids at the same time… Currently, the recommended safe dose of leucine is up to 550 mg / kg of body weight per day in adults. At the same time, further research is required to determine the safe dose of taking leucine, isoleucine and valine simultaneously.

Numerous short-term studies in animals and humans have confirmed that taking leucine, or other essential amino acids, both during rest and after exercise, stimulates muscle protein synthesis and reduces muscle catabolism. However, the number of long-term studies devoted to this issue is limited. Stoppani and colleagues conducted a study in which participants consumed supplements of BCAAs, whey protein, or a carbohydrate placebo (all at 14 grams per day) for eight weeks of strength training. After completing the experiment, the BCAA group showed an increase of 4 kg dry weight, a 2% reduction in body fat, and an increase in bench press performance by 6 kg (with the number of repetitions up to 10). All indicators significantly exceeded the indicators of other groups. It should be noted, however, that this study has not yet been reviewed.

Eating BCAAs between meals can help maintain muscle protein synthesis. Evidence from animal studies suggests that BCAA supplementation between meals can overcome the refractive period (the period when plasma amino acid levels rise while protein synthesis is still reduced). However, there are currently no long-term studies on the effect of BCAA consumption between meals on lean body mass gain. In addition, it should be borne in mind that the metabolism in rodents is different from that in humans, so that these results may not be identical in experiments with humans… Thus, long-term human research is required on this issue.

Arginine

Arginine supplements are typically taken by bodybuilders before exercise to increase blood flow to muscles during exercise, stimulate protein synthesis, and improve athletic performance. However, there is currently little research to support these properties of arginine. Thus, in a study by Faha and colleagues young people were asked to take 7 g of arginine or a placebo immediately before exercise, while the specialists did not note significant differences in muscle blood flow between the two groups.

Tang et al. conducted a study in which participants took 10 grams of arginine or a placebo before exercise and found no significant difference between the groups in either protein synthesis or muscle blood flow. Moreover, arginine is not an essential amino acid. Based on the paucity of existing data, it can be assumed that taking arginine does not affect muscle blood flow and protein synthesis in any way.

Overall, the evidence for arginine supplementation is conflicting. Approximately half of the studies on this issue found a positive effect of arginine supplementation, while in the second half of the studies, no such effects were noted. Also, Greer and colleagues found that taking arginine negatively affected muscle endurance, which led to a 2-4-fold reduction in the total number of repetitions when performing endurance tests. The authors concluded that arginine supplementation had little effect on athletic performance in healthy trained individuals… So, at the moment, additional research is required on this issue. At the same time, the dosage in which most athletes take arginine is significantly lower than the maximum recommended (20 g per day), so we can talk about the safety of its use.

Citrulline malate

Recently, citrulline malate (CM) supplementation has gained popularity among bodybuilders. However, there is currently not much scientific evidence to support the effectiveness of this supplement. Theoretically, CM intake “works” in three ways: 1. CM is an important component of the urea cycle, and thus can promote the elimination of ammonia 2. CM is an intermediary in the tricarboxylic acid cycle and prevents the accumulation of lactic acid 3. Citrulline can be converted to arginine (but, as discussed above, arginine does not have an ergogenic effect on young healthy athletes, so this point can be excluded).

Taking CM for 15 days can increase ATP synthesis by 34% during exercise, increase the rate of recovery of phosphocreatine levels by 20%, and reduce the subjective feeling of fatigue. In addition, taking 8 g of CM before doing pectoral exercises helped increae repetitions by 53% and also reduced inflammation by 40% in the 24-hour and 48-hour periods after exercise. Further, Stoppani et al. reported an increase in lean body weight by 4 kg, a decrease in body fat by 2 kg, and an increase in bench press performance by 6 kg (with a maximum number of repetitions of 10). This effect was noted by the authors after taking a drink (containing 14 g of BCAA, glutamine and CM) for 8 weeks. However, not all studies have unequivocally confirmed the efficacy of CM. Thus, Sureda and colleagues did not find significant differences in athletic performance among two groups of cyclists (one of which took 6 g of CM before the 137 km race). Hickner and colleagues reported that the time to muscle wasting on a treadmill was reduced by 7 seconds due to CM supplementation. In addition, the long-term safety of CM use remains unexplored. In general, at the moment it is impossible to make an unambiguous conclusion about the effectiveness of CM intake and further research is required.

Glutamine

Glutamine is the most abundant non-essential amino acid in muscle tissue. Intake of less than 14 grams of glutamine per day is safe for healthy adults. However, at the moment there are few data on the effect of glutamine intake on the body of an athlete. In the short term, glutamine supplementation does not have any significant effect on athletic performance nor does it help improve immune function or relieve muscle inflammation after exercise. Long-term studies of glutamine supplementation, including in combination with creatine monohydrate, citrulline malate, whey protein and/or BCAAs, have shown an increase in lean muscle mass of 1.5-2 kg, as well as an average improvement in bench press performance by 6 kg … However, the role of glutumin in achieving these results remains unclear.

Only one study looked at glutamine supplementation alone, combined with 6 weeks of strength training. At the same time, there were no significant differences in the growth of muscle mass, as well as in the rate of breakdown of muscle proteins compared with the control group. Although previous studies have not shown the effectiveness of gutamine in terms of athletic performance, it should be noted that taking a glutamine supplement can positively affect the health of the gastrointestinal tract and the absorption of peptides in people under stress. Overall, research results do not support the ergogenic properties of glutamine.

Caffeine

Caffeine is the most common stimulant taken by bodybuilders before exercise. Numerous studies support the effectiveness of caffeine supplementation in improving athletic performance during endurance training, sprinting, and strength training. It should be noted that in most studies, high doses of caffeine (5-6 mg/kg) were required to achieve significant improvements in athletic performance. This dosage is at the upper limit of the recommended intake (6 mg/kg). With continued use of caffeine, the ergogenic effect is usually reduced… Thus, the intake of caffeine in an amount of 5-6 mg/kg provides an ergogenic effect, at the same time, to achieve the best performance, it must be consumed cyclically.

Micronutrients

A number of studies have reported deficiencies in micronutrients such as vitamin D, zinc, magnesium and iron among bodybuilders on a diet [3,17,18,204,205]. It should be borne in mind that these results were obtained in the course of studies conducted about 20 years ago, and micronutrient deficiencies could arise as a result of monotonous diets. In this regard, additional research is required in order to establish whether micronutrient deficiencies are possible when following a modern diet containing a variety of foods. In general, based on the results of old studies, the intake of small doses of certain micronutrients may be justified in the context of a competitive diet, but this issue requires further clarification.