Amino acid supplements to improve athletic performance

Dietary Supplements Use among Athletes in Lebanon: Knowledge, Attitudes, Practices, and Correlates

Athletes are under the utmost pressure to reach excellence in their performance and achieve the desired outcomes in competitions, prompting them to use dietary supplements. Given the threats to both health and eligibility, it is crucial to observe the prevalence, sources of information, knowledge, attitudes, and practices (KAPs) among Lebanese athletes practicing their sports for at least two years. In the present paper, a cross-sectional study is performed using the snowball sampling method, in which a self-administered KAP questionnaire is used to collect data from 455 athletes (mean age: 27.4 ± 7.9 years; men: 73.1%) participating in four sports categories (ball games, combat sports, endurance sports, and weightlifting). Among the Lebanese athletes, the prevalence of dietary supplement (DS) use was 74%, where half of them had predominately used sports supplements. Athletes in Lebanon heavily rely on coaches (74%) and online sources, including webpages and social media (64%), as key information sources for DSs. The findings suggest that significant proportions of athletes show knowledge deficits and unsatisfactory attitudes towards multiple aspects related to supplementation. Moreover, education and sports type modulate the use of DSs among athletes. Furthermore, 34% reported using supplements without a recommendation from specialists, and 69% admitted to not reading the supplement's nutrition facts. This study urges the need for the regulation of concerned authorities and education programs to help overcome the existing challenges.

Effects of supplemental GAKIC ingestion on resistance training performance in trained men

PURPOSE

Glycine-arginine-alpha-ketoisocaproic acid (GAKIC) is a relatively new supplement that athletes and fitness enthusiasts ingest to enhance performance during anaerobic exercise. Therefore, the purpose of this study was to investigate the potential ergogenic effects of GAKIC ingestion during multiple bouts of resistance exercise.

METHOD

Seven resistance-trained men participated in a randomized, counterbalanced, double-blind study. Participants were randomly assigned to placebo or GAKIC (10.2 g) and performed 5 sets of 75% of 1-repetition maximum leg press to failure. Total load volume was calculated by multiplying the 75% of 1-repetition maximum mass lifted by the sum of repetitions to failure. One week later, participants ingested the other supplement (placebo or GAKIC) and the same exercise protocol was performed (i.e., crossover). Blood lactate, glucose, and heart rate were determined preexercise and immediately postexercise.

RESULTS

GAKIC supplementation significantly increased leg-press total load volume (GAKIC = 31,564 +/- 9,132 kg; placebo = 25,763 +/- 6,595 kg, p < .05). Heart rate and blood lactate were significantly increased (p < .05) postexercise compared with preexercise but were not significantly different between GAKIC and placebo. No significant changes (p > .05) were detected for one-repetition maximum and blood glucose.

CONCLUSIONS

These novel findings suggest that GAKIC increases total work performed during repeated bouts of lower-body resistance exercise. Thus, our data suggest that GAKIC ingestion before weight training may increase the training volume of athletes and resistance-trained individuals.

Nutrition concepts for elite distance runners based on macronutrient and energy expenditure

CONTEXT

Elite distance runners (EDR) must optimize their nutrition to maintain their demanding training schedules.

OBJECTIVE

To develop a nutrition concept for EDR based on energy and macronutrient expenditures.

DESIGN

This theoretical study provides calculations for macronutrient and energy expenditures of EDR. Anthropometric and metabolic characteristics of EDR were assumed based on average real EDR.

SETTING

University of Kiel.

PATIENTS OR OTHER PARTICIPANTS

Three prototypic types of male EDR described in the literature as type I (TI; body mass = 72 kg, respiratory quotient = 0.9 at rest, fast-twitch muscle fibers = 60% to 70%), type II (TII; body mass = 67 kg, respiratory quotient = 0.82 at rest, fast-twitch muscle fibers = 50%), and type III (TIII; body mass = 60 kg, respiratory quotient = 0.75 at rest, fast-twitch muscle fibers = 30% to 40%).

MAIN OUTCOME MEASURE(S)

We calculated the macronutrient and energy expenditures of the 3 types of EDR according to body mass, respiratory quotient, and percentage of fast-twitch muscle fibers.

RESULTS

We found that the average energy expenditure was 3750 kcal . d(-1) for TI runners, 3463 kcal . d(-1) for TII runners, and 3079 kcal . d(-1) for TIII runners. The carbohydrate (CHO) expenditure reached an average value of 10.0 g . kg(-1) . d(-1) for TI runners, 8.0 g . kg(-1) . d(-1) for TII runners, and 4.7 g . kg(-1) . d(-1) for TIII runners. When the EDR accomplished running sessions at a pace >or=100% of maximum oxygen consumption, all types of runners had a CHO demand of about 10 g . kg(-1) . d(-1). The TI and TII runners need a CHO intake of 8 to 10 g . kg(-1) . d(-1). For the TIII runners, a CHO intake >6 g . kg(-1) . d(-1) is necessary during anaerobic training sessions.

CONCLUSIONS

Nutrition concepts must be differentiated for EDR according to metabolic and anthropometric characteristics of the runners and their special training emphases.

Loss of skeletal muscle mass in aging: Examining the relationship of starvation, sarcopenia and cachexia

A loss of body weight or skeletal muscle mass is common in older persons and is a harbinger of poor outcome. Involuntary weight loss can be categorized into three primary etiologies of starvation, sarcopenia, and cachexia. Starvation results in a loss of body fat and non-fat mass due to inadequate intake of protein and energy. Sarcopenia is associated with a reduction in muscle mass and strength occurring with normal aging, associated with a reduction in motor unit number and atrophy of muscle fibers, especially the type IIa fibers. The loss of muscle mass with aging is clinically important because it leads to diminished strength and exercise capacity. Cachexia is widely recognized as severe wasting accompanying disease states such as cancer or immunodeficiency disease, but does not have a universally accepted definition. The key clinical question is whether these changes in body composition are distinct entities or represent an interdependent continuum. The importance of defining the distinction lies in developing a targeted therapeutic approach to skeletal muscle loss and muscle strength in older persons. Failure to distinguish among these causes of skeletal muscle loss often results in frustration over the clinical response to therapeutic interventions.

Interrelationship between physical activity and branched-chain amino acids

Some athletes can have quite high intakes of branched-chain amino acids (BCAAs) because of their high energy and protein intakes and also because they consume protein supplements, solutions of protein hydrolysates, and free amino acids. The requirement for protein may actually be higher in endurance athletes than in sedentary individuals because some amino acids, including the BCAAs, are oxidized in increased amounts during exercise compared with rest, and they must therefore be replenished by the diet. In the late 1970s, BCAAs were suggested to be the third fuel for skeletal muscle after carbohydrate and fat. However, the majority of later studies, using various exercise and treatment designs and several forms of administration of BCAAs (infusion, oral, and with and without carbohydrates), have failed to find a performance-enhancing effect. No valid scientific evidence supports the commercial claims that orally ingested BCAAs have an anticatabolic effect during and after exercise in humans or that BCAA supplements may accelerate the repair of muscle damage after exercise. The recommended protein intakes for athletes (1.2 to 1.8 g . kg body mass(-1) . d(-1)) do not seem to be harmful. Acute intakes of BCAA supplements of about 10-30 g/d seem to be without ill effect. However, the suggested reasons for taking such supplements have not received much support from well-controlled scientific studies.

Ornithine decarboxylase activity is inhibited by the polyamine precursor amino acids at the protein stability level in Caco-2 cells

High concentrations of certain amino acids are known to affect hormonal secretion, immune function, electrolyte balance or metabolic functions. However, there is a lack of knowledge regarding the molecular mechanisms responsible for these effects. We showed that, as well as spermidine transport, the activity of ornithine decarboxylase (ODC), the first and rate-limiting enzyme in polyamine biosynthesis, is decreased in human colon adenocarcinoma cells, Caco-2, following a 4-h supplementation with one of the two polyamine precursor amino acids, L-arginine or L-methionine. Dose-response assays indicated that the inhibitory effect of supplemental L-methionine was stronger than that of supplemental L-arginine. However, it was transient, being even replaced by ODC induction after 8 h, whereas the inhibitory effect of L-arginine lasted for at least 8 h. Unlike L-cysteine, neither L-methionine nor L-arginine could inhibit ODC activity in a crude acellular preparation of the enzyme. The inhibition of ODC activity in cells exposed to L-methionine or L-arginine was due to a decreased abundance of ODC protein without change at the mRNA level and each of these amino acids could counteract ODC induction by a glycine supplement. Contrary to the latter, supplemental L-methionine or L-arginine induced a marked decrease in ODC half-life, concomitantly with an increase in the activity of antizyme, an ODC inhibitory protein. Thus, depending on their nature, amino acids can up- or downregulate ODC activity at the protein stability level.

The college athlete

Participation in sports is important to many college students. Student athletes come from different levels of previous sport experience as they enter collegiate athletics. The primary source of student medical care is the campus student health center. The health care providers at student health centers attend to many of the sports-related concerns of student athletes. Preparticipation evaluation provides an opportunity to assess the general health of the student athlete and to identify conditions that might increase the risk of further injury. Sudden cardiac death and sports-associated concussions have generated much interest and are reviewed in this article. Other areas reviewed here include use of drugs and supplements, ankle sprains, acute knee ligament injuries, back pain, and shoulder impingement syndrome.

Glycine-Arginine-??-Ketoisocaproic Acid Improves Performance of Repeated Cycling Sprints

PURPOSE

The purpose of this study was to determine the effect of glycine-arginine-alpha-ketoisocaproic acid (GAKIC) supplementation on repeated bouts of anaerobic cycling performance.

METHODS

Ten men completed a randomized, double-blinded, placebo-controlled exercise protocol of two sessions separated by 7 d. Plasma lactate was analyzed in blood collected 45 min before exercise (REST) and 5 min postexercise (POST). Subjects consumed either 11.2-g GAKIC or placebo (PLC) during a 45-min period between the REST and exercise. Mean power, peak power, and fatigue values were assessed from five supramaximal, 10-s cycle ergometer sprints, separated by 1-min rest intervals. Data were analyzed using repeated measures ANCOVA.

RESULTS

A significant treatment x time interaction (P = 0.039) was observed for the change in mean power output over the five sprints between the GAKIC and PLC treatments. Post hoc analyses revealed a greater retention of mean power (P = 0.038) between sprints 1 and 2 after GAKIC (-1 +/- 9 W) versus PLC treatment (-47 +/- 18 W). No other performance variables differed between PLC and GAKIC. POST lactate was increased (P < 0.001) above REST, but there was no difference between treatments (P = 0.936).

CONCLUSION

These data support an ergogenic effect of GAKIC for attenuating the decline in mean power during repeated bouts of supramaximal exercise.

Adjusting a biochemistry course for physical education majors: A case study

The purpose of this study was to investigate and analyze the events responsible for curricular characteristics that lead to positive outcomes in university teaching using a biochemistry course taught to physical education students as a model. The research was carried out as a case study, supported by questionnaires, classroom observation, document analysis, and interviews. The overall analyses of obtained data were validated by means of triangulation protocols, which proved the following reasons for the course achievements: 1) teaching staff deeply committed to the course; 2) contents adaptation to students' careers; 3) gradual adjustment of the teaching strategies and evaluation tools; 4) valorization of formative evaluation; and 5) providing a suitable affective milieu.

Popular sports supplements and ergogenic aids

This article reviews the evidence-based ergogenic potential and adverse effects of 14 of the most common products in use by recreational and elite athletes today. Both legal and prohibited products are discussed. This is an aggressively marketed and controversial area of sports medicine worldwide. It is therefore prudent for the clinician to be well versed in the more popular supplements and drugs reputed to be ergogenic in order to distinguish fact from fiction.Antioxidants, proteins and amino acids are essential components of diet, but additional oral supplementation does not increase endurance or strength. Caffeine is ergogenic in certain aerobic activities. Creatine is ergogenic in repetitive anaerobic cycling sprints but not running or swimming. Ephedrine and pseudoephedrine may be ergogenic but have detrimental cardiovascular effects. Erythropoietin is ergogenic but increases the risk of thromboembolic events. beta-Hydroxy-beta-methylbutyrate has ergogenic potential in untrained individuals, but studies are needed on trained individuals. Human growth hormone and insulin growth factor-I decrease body fat and may increase lean muscle mass when given subcutaneously. Pyruvate is not ergogenic. The androgenic precursors androstenedione and dehydroepiandrosterone have not been shown to increase any parameters of strength and have potentially significant adverse effects. Anabolic steroids increase protein synthesis and muscle mass but with many adverse effects, some irreversible. Supplement claims on labels of product content and efficacy can be inaccurate and misleading.

Tyrosine improves appetite, cognition, and exercise tolerance in activity anorexia

PURPOSE

We have modified for mice the activity wheel model of Routtenberg to study the effects of tyrosine on exercise tolerance, behavior, and brain neurochemistry.

METHODS

Mice were fed for 2 h.d(-1) over a 2-wk period. During the second week, each group was injected daily with either saline or tyrosine (100 mg.kg(-1).d(-1)) and exercised on a running wheel. Controls were in cages with inactivated wheels and received the same treatment and feeding protocols as the experimental groups. Food consumption and cognitive function (eight-arm maze) were evaluated for 1 wk. Brains were then assayed for adrenergic and serotonergic metabolites.

RESULTS

Activity together with a restricted diet caused extreme weight loss (27%) (P < 0.001) together with decreased food consumption (22%) (P < 0.001). Tyrosine restored food consumption to that of the controls (P < 0.001) with no effect on weight, since there was a 22% increase in activity (P < 0.001). Saline injections caused an 18% decrease in activity (P < 0.001). Both activity and tyrosine improved maze performance (P < 0.05). In the hypothalamus, activity caused a significant increase in 5-hydroxytryptamine (5-HT) (P < 0.001), 5-hydroxyindoleacetic acid (5-HIAA) (P < 0.01), and dopamine (P < 0.05); tyrosine prevented the increase in 5-HT (P < 0.05) and increased 5-HIAA in the controls (P < 0.01). With regard to hippocampal 5-HT, there was a significant increase in 5-HIAA following activity (P < 0.05), whereas tyrosine caused significant increase in 5-HIAA in the controls (P < 0.01). Activity significantly decreased the level of hippocampal 3,4-dihydroxyphenylacetic acid (DOPAC), whereas tyrosine decreased its level only in the controls (both at P < 0.0001). The level of tyrosine hydroxylase increased with activity (P < 0.05), and tyrosine decreased it significantly (P < 0.05).

CONCLUSION

Activity anorexia is associated with increased hypothalamic 5-HT concentrations. Tyrosine administration reverses this, and significantly improves food consumption, cognitive behavior, and activity performance. Such nutritional modulations may have implications for the treatment of eating disorders and, in normal circumstances, tyrosine may improve exercise tolerance and delay fatigue.