Glutamine: the nonessential amino acid for performance enhancement

Surface Electromyography Assessments of the Vastus medialis and Rectus femoris Muscles and Creatine Kinase after Eccentric Contraction Following Glutamine Supplementation

Purpose

L-glutamine is the most abundant amino acid found in human muscle and plays an important role in protein synthesis and can reduce the levels of inflammation biomarkers and creatine kinase (CK) after training sessions. Delayed onset muscle soreness (DOMS) develops after intense exercise and is associated with an inflammatory response. The purpose of this study was to investigate the effect of glutamine supplementation on surface electromyography activity of the vastus medialis muscle (VMM) and rectus femoris muscle (RFM) and levels of creatine kinase after an eccentric contraction.

Methods

Seventeen healthy men (age: 22.35±2.27yr; body mass: 69.91± 9.78kg; height: 177.08±4.32cm) were randomly assigned to experimental (n=9) and control groups (n=8) in a double-blind manner. In both groups, subjects were given L-glutamine supplementation (0.1g.kg^-1) or placebo three times a week for 4 weeks. Median frequency (MDF) and mean power frequency (MPF) for VMM and RFM muscles and also CK measurements were performed before, 24h and 48 h after a resistance training session. The resistance training included 6 sets of eccentric leg extensions to exhaustion with 75% of 1RM.

Results

There was no significant difference between groups for MDF or MPF in VMM and RFM. The difference of CK level between the groups was also not significant.

Conclusion

The results of this study indicate that glutamine supplementation has no positive effect on muscle injury markers after a resistance training session.

Effect of glutamine and maltodextrin acute supplementation on anaerobic power

Purpose

The aim of this study was to investigate whether supplementation of carbohydrate together with peptide glutamine would prevent anaerobic power decrease during repeated competitions.

Methods

Twenty eight physical education male students voluntarily participated in the study. Subjects were randomly divided on a maximal power (Max power) output value basis into four groups: 1) G group (oral ingestion of glutamine at the dose of 0.25 g/kg body mass in 250 ml of water), 2) M group (a single carbohydrate at a concentration of 50g of maltodextrin in 250 ml of water), 3) GM group (carbohydrate at a concentration of 50g of maltodextrin + glutamine at the dose of 0.25 g/kg body mass in 250 ml of water) and, 4) P group (just 250 ml of water and 30 gram sweetener). Each subject performed three times Running-based Anaerobic Sprint Test (RAST) with intervals of 1 hour. Max power, Minimal power (Min power) and fatigue were calculated for each participant.

Results

There was a significant decrease in Max and Min power in P group in time series (P<0.05). Furthermore, regarding the Max and Min power, there was significant difference between P and GM group in third bout indicating stronger influence of combination of maltodextrin and glutamine in comparison with pure consumption of glutamine and maltodextrin (P< 0.05).

Conclusions

It seems acute supplementation of glutamine and maltodextrin combination, 2 hours before exercise is more efficient in prevention of anaerobic power decrease than consumption of a pure carbohydrate or glutamine in repeated bouts of RAST protocol. Thus, supplementation with both carbohydrate and peptide glutamine improved the physical performance of athletes during repeated competitions. Obviously, it is necessary to do further studies.

Improved training tolerance by supplementation with α-Keto acids in untrained young adults: a randomized, double blind, placebo-controlled trial

Background

Exercise causes a variety of physiological and metabolic changes that can in turn reduce exercise tolerance. One of the potential mechanisms responsible for fatigue is “exercise-induced hyperammonemia”. Previous studies have shown that supplementation with amino acids can increase training tolerance. The α-keto acids are biochemical analogs of amino acids and can be converted to amino acids through transamination, thus reducing the cellular ammonia level. This double blind, placebo-controlled study was designed to investigate the effects of α-keto acid supplementation (KAS) on training tolerance, training effect, and stress-recovery state.

Methods

Thirty-three untrained young male adults underwent four weeks of training (5 sessions/week; 30 minutes running at the individual anaerobic threshold followed by 3 x 3 minute sprints/each session). Throughout the 4 weeks of training and one week of recovery, subjects took α-ketoglutarate (AKG group, 0.2 g/kg/d, n = 9), branched-chain keto acids (BCKA group, 0.2 g/kg/d, n = 12) or isocaloric placebo (control group, n = 12) daily.

Results

The 4^th week training volume, maximum power output and muscle torque were higher in the AKG group (175 ± 42 min, 412 ± 49 Watts and 293 ± 58 Newton meters, respectively, P<0.05) and the BCKA group (158 ± 35, 390 ± 29 and 273 ± 47, P<0.05) than in the control group (92 ± 70, 381 ± 67 and 233 ± 43). The general stress and emotional exhaustion as assessed by the rest-stress-questionnaire-sport after the 3^rd week of training increased significantly in the control group (P<0.05), but not in the KAS groups.

Conclusions

Under KAS, subjects could bear a higher training volume and reach a higher power output and peak muscle torque, accompanied by a better stress-recovery-state. Thus, KAS improves exercise tolerance and training effects along with a better stress-recovery state. Whether the improved training tolerance by KAS is associated with effects on ammonia homeostasis requires further observation.

Effects of multi-ingredient supplementation on resistance training in young males

Muscle strength and fatigue resistance increases with resistance training. Resistance training adaptations can be enhanced with single-ingredient or dual-ingredient supplementation but less is known about resistance training adaptations by multi-ingredient supplementation. We examined the effects of a commercial multi-ingredient supplement on resistance training adaptations for training-specific and non-training-specific tasks in young males. Male participants (n = 16, age 21±2 years, body mass 74.5±5.9 kg, body height 177±5 cm) had at least 1 year experience with resistance training exercises. Training (7 muscle groups, 4 sessions/week, weekly adjustments) consisted of two 6 weeks blocks with 4 weeks between blocks. During training, participants consumed placebo (i.e. maltodextrin, n = 7) or the sports nutritional supplement Cyclone (Maximuscle Ltd, UK, n = 9) (main ingredients creatine monohydrate, whey protein, glutamine and HMB) twice daily with one intake <15 min following a training session. Unpaired Student’s t-test was used for placebo and Cyclone group comparison of percentage changes with p < 0.05. Effect sizes (Cohen’s d) were calculated for the Cyclone group. Cyclone did not enhance maximal voluntary isometric force (MVIF) (p = 0.56), time to fatigue at 70% MVIF (p = 0.41) and peak concentric strength (60°·s⁻¹) (p = 0.66) of m.quadriceps femoris (i.e. the non-specific training tasks). For the specific-training tasks, Cyclone did not enhance one-repetition maximum (1-RM) of lateral pull (p = 0.48) but there was a trend and large effect size for 1-RM of bench press (p = 0.07, d = 0.98) and 45° leg press (p = 0.07, d = 1.41). Cyclone resulted in an increase in number of repetitions for 80% pre-training 1-RM for lateral pull (p = 0.02, d = 1.30), bench press (p = 0.03, d = 1.20) with a trend for 45° leg press (p = 0.08, d = 0.96). Cyclone during resistance training enhanced the performance of 1-RM and number of repetitions at 80% of pre-training 1RM of some training-specific tasks, all with large effect sizes. Our observations suggest that Cyclone during resistance training substantially improves the ability to perform training-related tasks.

Dietary exercise as a novel strategy for the prevention and treatment of metabolic syndrome: effects on skeletal muscle function

A sedentary lifestyle can cause metabolic syndrome to develop. Metabolic syndrome is associated with metabolic function in the skeletal muscle, a major consumer of nutrients. Dietary exercise, along with an adequate diet, is reported to be one of the major preventive therapies for metabolic syndrome; exercise improves the metabolic capacity of muscles and prevents the loss of muscle mass. Epidemiological studies have shown that physical activity reduces the risk of various common diseases such as cardiovascular disease, diabetes, and cancer; it also helps in reducing visceral adipose tissue. In addition, laboratory studies have demonstrated the mechanisms underlying the benefits of single-bout and regular exercise. Exercise regulates the expression/activity of proteins associated with metabolic and anabolic signaling in muscle, leading to a change in phenotype. The extent of these changes depends on the intensity, the duration, and the frequency of the exercise. The effect of exercise is also partly due to a decrease in inflammation, which has been shown to be closely related to the development of various diseases. Furthermore, it has been suggested that several phytochemicals contained in natural foods can improve nutrient metabolism and prevent protein degradation in the muscle.