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L-glutamine supplementation: Effects on endurance, power and recovery
Abstract
The purpose was to examine the influence of L-Glutamine on endurance and power. Cardio-respiratory capacity (VO2peak) was determined in 12 men using a cycle ergometer. After 2 days, subjects performed 3 Wingate tests to assess total revolutions (TR), peak (PP) and mean Power (MP); and a time trial to exhaustion (TTE). Two Wingates were conducted before and immediately after the TTE, the third after 24hrs. Subjects were then randomized to either L-glutamine (GLU) or placebo (CON) for 6 days. After 6 days all tests, except the VO2peak, were repeated. There were no group differences for VO2peak, power indices, and TTE before supplementation. Both groups showed a similar drop in power (TR:-22%; PP:-27%; MP:-27%, p<0.001) immediately after the TTE, with incomplete recovery at 24hrs. After 6 days, GLU improved TTE by 3.16±0.75min (p<0.05) compared to no change in CON. Delta values (Post-Pre supplementation) revealed group differences for TR (GLU: Δ1.83±4.79; CON: Δ-5.33±4.13; p=0.02), PP (GLU: Δ-58.59±50.52; CON:-Δ113.67±63.35, p=0.12), and MP (GLU: Δ28.93±75.02; CON: Δ-72.25±62.14, p=0.02). No effects were noted immediately and 24hrs after the TTE. These findings suggest 6 days of glutamine supplementation does not affect acute recovery from exhaustive exercise; but does increase endurance and restores and/or improves power indices.
... However, glutamine (GLN), which is a nonessential amino acid, is different. Certain well-regarded scientific studies have shown GLN supplementation to have specific benefits, including supporting the immune system, increasing glycogen production, anticatabolic effects, and increasing the absorption of water and electrolytes [6]. In laboratory animals, a direct relationship has been shown between free GLN levels in muscle, and the rate of muscle protein synthesis [7]. ...
... In three studies no significant difference was observed between GLN and placebo groups in heart rate measurements [47,58,66]. Three studies found a significant increase in peak, minimum and mean anaerobic power (Rast or Wingate test) following GLN supplementation compared to a placebo [6,63,70]. On the other hand, in one study the authors did not find any significant relationship between GLN supplementation and improvement in anaerobic performance (measured by shuttle run test), upper limb muscle strength (evaluated by pushups), lower limb muscle strength (evaluated by horizontal jump), flexibility (determined by the sit and reach test), and abdominal muscle endurance (determined by sit-up test) [71]. According to one study, the lactate threshold and lactate tolerance did not change following GLN supplementation, in comparison with placebo groups [10]. ...
... One study showed that GLN supplementation caused an improvement in total distance covered and duration of tolerance [61]. Two other studies showed that subjects who received GLN supplements experienced less fatigue than the placebo group and that the mean time until fatigue or exhaustion was longer for athletes in the GLN group [6,61]. In contrast, one study reported a small increase in leg muscle tiredness with GLN supplementation, compared to glucose or a placebo [68]. ...
Background & aim:
This systematic review and meta-analysis of available evidence was conducted to obtain a conclusive result on the effects of glutamine supplementation on athletes.
Methods:
Systematic review and meta-analysis. Data related to body mass, lean body mass, body fat percentage, Vo2 max, lymphocytes, leukocytes and neutrophil counts were extracted to determine the effects of GLN on performance outcomes.
Data sources:
The literature search was conducted across the databases Pubmed, Scopus, ISI Web of Science, SID (Scientific Information Database) and Cochrane Central Register of Controlled Trials, covering a period up to January 2017.
Eligibility criteria for selecting studies:
Clinical trials evaluating glutamine supplementation outcomes on athletes aged over 18 were included.
Results:
A total of 47 studies were included in the systematic review, and 25 trials matched the inclusion criteria for the meta-analysis. According to the meta-analysis, glutamine has a significant effect on weight reduction (WMD = -1.36 [95% CI: -2.55 to -0.16], p = 0.02). Moreover, neutrophil numbers were reduced following glutamine intake at doses greater than 200 mg/kg body weight (WMD = -605.77 [95% CI: -1200.0 to 52.1]; P = 0.03). Also, supplementation by glutamine dipeptide resulted in higher blood glucose after exercise (WMD = 0.51 [95% CI: 0.18, 0.83] mmol/l; P = 0.002). There was no association between glutamine ingestion and other outcomes investigated.
Conclusion:
According to this meta-analysis, generally, glutamine supplementation has no effect on athletics immune system, aerobic performance, and body composition. However, the current study showed that glutamine resulted in greater weight reduction. In addition, the present study suggests that the efficacy of glutamine supplementation on neutrophil numbers could be affected by supplement type and dose.
... However, glutamine (GLN), which is a nonessential amino acid, is different. Certain well-regarded scientific studies have shown GLN supplementation to have specific benefits, including supporting the immune system, increasing glycogen production, anticatabolic effects, and increasing the absorption of water and electrolytes [6]. In laboratory animals, a direct relationship has been shown between free GLN levels in muscle, and the rate of muscle protein synthesis [7]. ...
... In three studies no significant difference was observed between GLN and placebo groups in heart rate measurements [47,58,66]. Three studies found a significant increase in peak, minimum and mean anaerobic power (Rast or Wingate test) following GLN supplementation compared to a placebo [6,63,70]. On the other hand, in one study the authors did not find any significant relationship between GLN supplementation and improvement in anaerobic performance (measured by shuttle run test), upper limb muscle strength (evaluated by pushups), lower limb muscle strength (evaluated by horizontal jump), flexibility (determined by the sit and reach test), and abdominal muscle endurance (determined by sit-up test) [71]. According to one study, the lactate threshold and lactate tolerance did not change following GLN supplementation, in comparison with placebo groups [10]. ...
... One study showed that GLN supplementation caused an improvement in total distance covered and duration of tolerance [61]. Two other studies showed that subjects who received GLN supplements experienced less fatigue than the placebo group and that the mean time until fatigue or exhaustion was longer for athletes in the GLN group [6,61]. In contrast, one study reported a small increase in leg muscle tiredness with GLN supplementation, compared to glucose or a placebo [68]. ...
Objective
Whether consumption of omega-3 affects circulating adiponectin is not established. The objective of his study was to evaluate the effect of omega-3 (food or supplement) on circulating adiponectin in patients with type 2 diabetes in a systematic review a meta-analysis of randomized controlled trials.
Methods
PubMed, Scopus and Web of Science were searched for relevant studies update to May 2016. Two researchers screened and abstracted the literature independently. Pooled estimates were obtained using random-effects models.
Results
Overall, omega-3 increased adiponectin by 0.57 µg/ml (95% confidence interval [CI] 0.15 to 1.31; p=0.01, I²=74.2% p for heterogeneity<0.001). The source of observed heterogeneity was explored by subgroup analyses. In subgroup analyses, adiponectin level increased only in those who had consumed omega-3 for more than 8 weeks.
Conclusions
This systematic review and meta-analysis of randomized, placebo-controlled clinical trials suggests that omega-3 in patients with T2DM increases circulating adiponectin. These findings support potential beneficial effects of dietary omega-3 in patients with T2DM on pathways related to adiponectin metabolism.
... Prior to the study, the athletes were asked whether they were allergic to the supplements. The supplementation method in the study was determined by considering the validated duration and dose applied in previous studies (Piattoly et al., 2013;Ahmadi et al., 2019;Wax et al., 2021). In the study, the athletes were administered glutamine and creatine at a dose of 5000 mg (5 g) 30 minutes before training and 5000 mg (5 g) immediately after training, for a total of 10,000 mg (5,000 mg glutamine, 5,000 mg creatine) for 7 days under the supervision of the researcher. ...
... Moreover, Johnston et al. (2009) reported that creatine supplementation (4 × 5 g·d−1 for 6 days) reduced muscle mass and strength loss in the upper limb in young men. Piattoly et al. (2013) reported that 6day glutamine supplementation did not affect acute recovery after strenuous exercise but improved time trial to exhaustion performance and enhanced power indices in WAnT in experienced cyclists. Also, relatively long-term creatine ingestion of 28 d, at a dose of 20 g/d on days 1-4, 10 g/d on days 5-6, and 5 g/d on days 7-28, improved repeated block jump performance in collegelevel basketball players (Lamontagne-Lacasse et al., 2011). ...
The aim of this study was to investigate the combined effect of glutamine (GLU) and creatine (CRE) supplementation on body composition, body hydration levels, and selected performance parameters in football players. Eight volunteer licensed male football players aged 19 to 23 participated in this study. The study was randomized and single-blinded. In the study, athletes were administered 10 g of glutamine and creatine before and after training for seven days. Some tests, measurements, and analyses were performed in equal physical conditions with seven-day intervals using a pre-test/post-test experimental design. The research data were analyzed with a dependent sample t-test. In the comparison of the parameters pre- and post-supplementation, statistically significant differences were found in body mass, skeletal muscle mass, total body water, body mass index (BMI), metabolic rate, protein, and mineral values (p
... There are few data on Gln as food supplement. However, some studies have proved its efficiency, protective and supportive role, especially among athletes (Ziegler et al., 1990;Piattoly, 2005). Significant reduction in Gln blood-concentration was noticed in cases of stress, clinical trauma, starvation, or prolonged exercise (Castell, 2002). ...
... Despite parenteral administration is recommended for Gln in clinical trials, the gastrointestinal tract absorbs Gln expeditiously (He et al., 2016). So, oral supplementation would be an effective vehicle of delivering the Gln dosage required by athletes (Piattoly, 2005). Therefore, the objectives of this study were production of L-glutamine fortified functional dairy products with acceptable sensory attributes ...
... Debido a que la glutamina participa en la síntesis de aminoácidos, ácidos nucleídos, glucógeno y otras moléculas biológicamente importantes en el metabolismo celular 20,21,24,25,26 , se ha considerado como posible estimulante para el anabolismo proteico, adjudicándole beneficios potenciales sobre el tejido muscular en diversas condiciones medicas 17,18,25,27,28,29 . ...
... Debido a que la glutamina participa en la síntesis de aminoácidos, ácidos nucleídos, glucógeno y Nutr Hosp. 2015;32(4):1443-1453 Glutamina como coadyuvante en la recuperación de la fuerza muscular: revisión sistemática de la literatura otras moléculas biológicamente importantes en el metabolismo celular 20,21,24,25,26 , se ha considerado como posible estimulante para el anabolismo proteico, adjudicándole beneficios potenciales sobre el tejido muscular en diversas condiciones medicas 17,18,25,27,28,29 . ...
Background:
after a traumatic injury or post surgical orthopedic, the loss of skeletal muscle strength is common. In addition to strength training schemes and/or resistance to treatment, it has been proposed as an additional treatment, the use of some amino acids such as glutamine (Gln) in isolation or combination with other nutrients. However, the information on the effectiveness of oral Gln supplementation during exercise strength schemes and / or endurance in adults with strength deficit is inconsistent.
Objective:
to evaluate the strength of the evidence at hand about the effect of oral supplementation on muscle strength Gln set to strength training schemes and / or resistance in adult muscle strength deficit.
Methods:
a systematic search was conducted in different databases, in clinical trials reported from the year 1980-2014, both in English and Spanish, about oral Gln supplementation alone or in combination with other nutrients, with a control group, in adults with strength deficits under exercise schemes of strength and / or endurance, tracking under a year and muscle power as the primary outcome.
Results:
of 661 articles, six relevant studies were identified. The study participants in Gln isolation evaluation did not suggest changes between the groups, only an improvement in the perception of muscle weakness. Studies evaluating Gln with other nutrients, have reported results in favor of it. No meta-analysis was possible.
Conclusions:
nowadays there are insufficient data on the effects related to the Gln on the deficit of muscular force during exercise schemes in adults. It is required more research in this topic to respond more accurately about this fact.
... Debido a que la glutamina participa en la síntesis de aminoácidos, ácidos nucleídos, glucógeno y otras moléculas biológicamente importantes en el metabolismo celular 20,21,24,25,26 , se ha considerado como posible estimulante para el anabolismo proteico, adjudicándole beneficios potenciales sobre el tejido muscular en diversas condiciones medicas 17,18,25,27,28,29 . ...
... Debido a que la glutamina participa en la síntesis de aminoácidos, ácidos nucleídos, glucógeno y Nutr Hosp. 2015;32(4):1443-1453 Glutamina como coadyuvante en la recuperación de la fuerza muscular: revisión sistemática de la literatura otras moléculas biológicamente importantes en el metabolismo celular 20,21,24,25,26 , se ha considerado como posible estimulante para el anabolismo proteico, adjudicándole beneficios potenciales sobre el tejido muscular en diversas condiciones medicas 17,18,25,27,28,29 . ...
GLUTAMINE AS AN AID IN THE RECOVERY OF MUSCLE STRENGTH: SYSTEMATIC REVIEW OF LITERATURE
Abstract
Background: after a traumatic injury or post surgical orthopedic, the loss of skeletal muscle strength is com- mon. In addition to strength training schemes and/or resistance to treatment, it has been proposed as an ad- ditional treatment, the use of some amino acids such as glutamine (Gln) in isolation or combination with other nutrients. However, the information on the effectiveness of oral Gln supplementation during exercise strength schemes and / or endurance in adults with strength de- ficit is inconsistent.
Objective: to evaluate the strength of the evidence at hand about the effect of oral supplementation on muscle strength Gln set to strength training schemes and / or re- sistance in adult muscle strength deficit.
Methods: a systematic search was conducted in diffe- rent databases, in clinical trials reported from the year 1980-2014, both in English and Spanish, about oral Gln supplementation alone or in combination with other nutrients, with a control group, in adults with strength deficits under exercise schemes of strength and / or en- durance, tracking under a year and muscle power as the primary outcome.
Results: of 661 articles, six relevant studies were iden- tified. The study participants in Gln isolation evaluation did not suggest changes between the groups, only an im- provement in the perception of muscle weakness. Studies evaluating Gln with other nutrients, have reported re- sults in favor of it. No meta-analysis was possible. Resumen
Antecedentes: la pérdida de fuerza del músculo es- quelético es frecuente tras una lesión traumática o en el postquirúrgico ortopédico. Además de los esquemas de ejercicio de fuerza y/o resistencia para su tratamiento, ha sido propuesto como auxiliar el uso de algunos aminoáci- dos como la glutamina (Gln), de manera aislada o combi- nada con otros nutrimentos. Sin embargo, la información sobre la eficacia de la suplementación oral con Gln du- rante los esquemas de ejercicio de fuerza y/o resistencia en adultos con déficit de fuerza es inconsistente.
Objetivo: evaluar la solidez de la evidencia disponi- ble del efecto de la suplementación oral con Gln sobre la fuerza muscular, junto con esquemas de ejercicio de fuerza y/o resistencia en adultos con déficit de fuerza muscular.
Métodos: se realizó una búsqueda sistemática en dife- rentes bases de datos, de ensayos clínicos reportados des- de el año 1980 a 2014, en idioma inglés y español, sobre suplementación oral con Gln aislada o combinada con otros nutrimentos, con grupo control, en adultos con dé- ficit de fuerza, bajo esquemas de ejercicio de fuerza y/o resistencia, seguimiento menor a un año y fuerza muscu- lar como desenlace primario.
Resultados: de 661 artículos, se identificaron seis es- tudios relevantes. El estudio con más participantes que evaluó la Gln aislada no sugiere cambios entre los gru- pos, solo una mejoría en la percepción de la debilidad muscular. Los estudios que evaluaron la Gln con otros nutrimentos reportan resultados a favor de esta. No fue posible realizar un metanálisis.
... Glutamine is recommended as an additional nutrient to prevent bacterial translocation in patients receiving radiotherapy or chemotherapy, fed parenterally for a long time, and in septic patients with small bowel damage expected. It has been demonstrated in clinical studies that multiple organ failure due to sepsis decreases in patients who are given glutamine as an additional nutrient (21). Glutamine is the leading molecule of glutathione, an antioxidant. ...
Objective:The aim of this experimental study is to research the effects of L-alanine and L-glutamine, which are being widely used on intensive care patients, on the liver, structural changes in the small intestine, wound healing, and bacterial translocation.Method:Twenty male Sprague Dawley rats which weighe 190-230 gr were used in this study. Rats were separated into two randomized groups. In accordance with experimental rat burn model, skin burn was created in every rat and both groups were fed equally for 21 days. The experimental group was administered L-glutamine + L-alanine containing product (Dipeptiven®, Fresenius Kabi BadHamborg, Germany) for 5 mL/kg/day orally. At the end of the 21st day, all rats were sacrificed. Biopsy materials were obtained from the liver, small intestine, and burn wound, and blood culture was taken under sterile conditions. In pathologic examination, structural changes in tissues and wound healing were evaluated. In microbiologic examination, the effects of L-glutamine and L-alanine on bacterial translocation were evaluated by comparing small intestine and blood cultures.Results:No structural difference was seen among small intestine biopsies between two groups. No liver damage was seen in the experimental group while live biopsies showed grade 1 damage in the control group. Epithelization and granulation were detected as better in the pathologic examination of skin biopsies obtained from burn wound in the experimental group. Microbiologic examination showed bacterial replication in a total of 4 rats from the control group, two rats showed replication of S. aures in the small intestine and blood culture and two rats showed replication of S. epidermidis in the small intestine and blood culture. No replication was determined in any rats from the experimental group.Conclusion:In the light of findings acquired from this study done with experimental rat burn model, we think that the use of L-glutamine + L-alanine will have positive effects on wound healing and help preventing the bacterial translocation in burn patients as a supporting product.
... These positive effects of Gln in the lymphocytes can be attributed mainly to the fact that this amino acid is largely used as the main energy source, which can lead to increased glycogen production. In addition, Gln also showed anticatabolic effects and improve water and electrolytes absorption, which in association with its "energetic" support can putatively influence the better "clonal expansion" capacity and in the immune response [11]. ...
Background:
Since aging affects the immune responses against vaccination, the present study evaluated the effects of L-glutamine (Gln) supplementation in the humoral and cellular immune responses in elderly subjects, practitioners or not, of physical exercise training.
Methods:
Eighty-four elderly people (aged 72.6 ± 6.1), non-practitioners (NP, n = 31), and practitioners of combined-exercise training (CET, n = 53) were submitted to Influenza virus vaccination and supplemented with Gln (0.3 g/kg of weight + 10 g of maltodextrin, groups: NP-Gln (n = 14), and CET-Gln (n = 26)), or placebo (10 g of maltodextrin, groups: NP-PL (n = 17), and CET-PL (n = 27)). Blood samples were collected pre (baseline) and 30 days post-vaccination and supplementation.
Results:
Comparing with the baseline values, whereas the NP-Gln and CET-PL groups showed higher specific-IgM levels, the CET-Gln group showed higher specific-IgM and IgA levels post-vaccination. The titer rate of hemagglutination inhibition was higher in the CET-Gln, NP-PL, and NP-Gln groups post-vaccination than baseline values. The absolute number of naive and effector CD4+ T cells was higher especially in the NP-Gln and CET-Gln groups, whilst activated CD4+ T cells were higher in CET subgroups post-vaccination.
Conclusion:
Our results showed that both l-glutamine supplementation and combined-exercise training can improve the immune responses to the Influenza virus vaccine in elderly subjects.
... 90 Significant delay in time to fatigue groups using glutamine has been reported to shorten the recovery time. 91 6 daily glutamine load increases resistance and contributes to the development of power. 59 Glutamine increases the recovery speed and load while increasing muscle glycogen levels in strenuous exercise, liver and contributes to the rise in carbohydrate stores. ...
ÖZ: Bu çalışmanın amacı glutamin ve kreatin kombine tüketiminin bisikletçilerin
performansına akut etkisinin incelenmesidir. Bu çalışmaya lisanslı, aktif ve antrenmanlı 8 erkek bisikletçi (yaş: 25,85 ± 9,75 yıl; boy uzunluğu: 174,71 ± 5,18 cm;
vücut ağırlığı: 69,81 ± 7,16 kg; beden kütle indeksi (BKİ): 22,95 ± 2,97 kg/m2
; sporcu yaşı: 5,28 ± 2,28) gönüllü olarak katıldı. Randomize, tek kör ve çapraz döngü
çalışmada, bisikletçiler rastgele 2 gruba ayrıldı ve 48 saat ara ile glutamin&kreatin (SUP) veya plasebo (PLA) alarak fonksiyonel eşik güç (FTP) testini uyguladı.
Testlerin ardından Borg Skalası, Görsel Analog Skala (GAS) ve Gastrointestinal
Semptom Derecelendirme Ölçeği (GSDÖ) uygulandı. Gruplar arası karşılaştırma
bağımlı örneklem t-test ile analiz edildi. Ayrıca etki büyüklüğünün hesaplanması
için Cohen’s d formülü uygulandı. Testler sonucunda kalp atım hızı (KAH), kadans, FTP (ortalama güç, W, W/kg), algılanan zorluk derecesi (AZD) ve GAS değerlerinde istatistiksel olarak anlamlı fark olmadığı tespit edildi (p>0,05). Ayrıca,
SUP grubu lehine kadans değerlerinde düşük (0,34) ve GAS değerlerinde yüksek
etki büyüklüğü (0,83) bulunurken, AZD değerlerinde PLA grubu lehine orta etki
büyüklüğü (0,61) tespit edildi. GSDÖ bulgularında gruplar arasında anlamlı bir
fark olmadığı tespit edildi (p>0,05). Sonuç olarak, çalışmamızda glutamin&kreatin
kombine tüketiminin fonksiyonel eşik güç (FTP) ve performans üzerine akut etkisinin olmadığı belirlenmiştir. Bununla birlikte, glutamin&kreatin tüketiminin kas
ağrılarına olumlu etki ettiği söylenebilir. Anahtar Kelimeler: Ergojenik Destek, Fonksiyonel Eşik Güç, Glutamin, Kreatin, Sporcu Beslenmesi. ABSTRACT: The aim of this study was to investigate the acute effect of the combined consumption of glutamine and creatine on the performance of cyclists. Eight licensed,
active, and trained male cyclists (age: 25.85 ± 9.75 years; height: 174.71 ± 5.18
cm; body weight: 69.81 ± 7.16 kg; body mass index (BMI): 22.95 ± 2.97 kg/m2; sports age: 5.28 ± 2.28 years) voluntarily participated in this study. In a randomized, single-blind, and cross-over design, the cyclists were randomly divided into 2
groups and performed the functional threshold power (FTP) test by taking glutamine&creatine (SUP) or placebo (PLA) at a 48-hour interval. The Borg Scale, Visual Analog Scale (VAS), and Gastrointestinal Symptom Rating Scale (GSRS) were
utilized at the end of the tests. Between-group comparisons were analyzed with
paired sample t-tests. Cohen’s d formula was applied to calculate the effect size. No
statistical significance was found in heart rate (HR), cadence, FTP (average power,
W, W/kg), rating of perceived exertion (RPE), and VAS values (p>0.05). Also, while there was a small effect size in cadence (0.34) and a large effect size in VAS (0.83)
in favor of the SUP group, a medium effect size (0.61) was observed in RPE in
favor of the PLA group. In GSRS results, no significant difference was observed
between the groups (p>0.05). In conclusion, it was determined that glutamine&creatine coingestion had no acute effect on functional threshold power (FTP) and performance. However, it can be said that glutamine & creatine consumption has a positive effect on muscle pain. Keywords: Creatine, Ergogenic Aid, Functional Threshold Power, Glutamine, Sports Nutrition.
Bu çalışmanın amacı glutamin ve kreatin kombine tüketiminin bisikletçilerin performansına akut etkisinin incelenmesidir. Bu çalışmaya lisanslı, aktif ve antrenmanlı 8 erkek bisikletçi (yaş: 25,85 ± 9,75 yıl; boy uzunluğu: 174,71 ± 5,18 cm; vücut ağırlığı: 69,81 ± 7,16 kg; beden kütle indeksi (BKİ): 22,95 ± 2,97 kg/m2; sporcu yaşı: 5,28 ± 2,28) gönüllü olarak katıldı. Randomize, tek kör ve çapraz döngü çalışmada, bisikletçiler rastgele 2 gruba ayrıldı ve 48 saat ara ile glutamin&kreatin (SUP) veya plasebo (PLA) alarak fonksiyonel eşik güç (FTP) testini uyguladı. Testlerin ardından Borg Skalası, Görsel Analog Skala (GAS) ve Gastrointestinal Semptom Derecelendirme Ölçeği (GSDÖ) uygulandı. Gruplar arası karşılaştırma bağımlı örneklem t-test ile analiz edildi. Ayrıca etki büyüklüğünün hesaplanması için Cohen’s d formülü uygulandı. Testler sonucunda kalp atım hızı (KAH), kadans, FTP (ortalama güç, W, W/kg), algılanan zorluk derecesi (AZD) ve GAS değerlerinde istatistiksel olarak anlamlı fark olmadığı tespit edildi (p>0,05). Ayrıca, SUP grubu lehine kadans değerlerinde düşük (0,34) ve GAS değerlerinde yüksek etki büyüklüğü (0,83) bulunurken, AZD değerlerinde PLA grubu lehine orta etki büyüklüğü (0,61) tespit edildi. GSDÖ bulgularında gruplar arasında anlamlı bir fark olmadığı tespit edildi (p>0,05). Sonuç olarak, çalışmamızda glutamin&kreatin kombine tüketiminin fonksiyonel eşik güç (FTP) ve performans üzerine akut etkisinin olmadığı belirlenmiştir. Bununla birlikte, glutamin&kreatin tüketiminin kas ağrılarına olumlu etki ettiği söylenebilir.
Glutamine is the most abundant free amino acid in human muscle and plasma and is utilised at high rates by rapidly dividing cells, including leucocytes, to provide energy and optimal conditions for nucleotide biosynthesis. As such, it is considered to be essential for proper immune function. During various catabolic states including surgical trauma, infection, starvation and prolonged exercise, glutamine homeostasis is placed under stress. Falls in the plasma glutamine level (normal range 500 to 750 μmol/L after an overnight fast) have been reported following endurance events and prolonged exercise. These levels remain unchanged or temporarily elevated after short term, high intensity exercise. Plasma glutamine has also been reported to fall in patients with untreated diabetes mellitus, in diet-induced metabolic acidosis and in the recovery period following high intensity intermittent exercise. Common factors among all these stress states are rises in the plasma concentrations of cortisol and glucagon and an increased tissue requirement for glutamine for gluconeogenesis. It is suggested that increased gluconeogenesis and associated increases in hepatic, gut and renal glutamine uptake account for the depletion of plasma glutamine in catabolic stress states, including prolonged exercise. The short term effects of exercise on the plasma glutamine level may be cumulative, since heavy training has been shown to result in low plasma glutamine levels ( Since injury, infection, nutritional status and acute exercise can all influence plasma glutamine level, these factors must be controlled and/or taken into consideration if plasma glutamine is to prove a useful marker of impending overtraining.
The purpose of this study was to examine the efficacy of L-alanyl-L-glutamine (AG) ingestion on basketball performance, including jump power, reaction time, shooting accuracy and fatigue.
Ten women (21.2 ± 1.6 years; height: 177.8 ± 8.7 cm; body mass: 73.5 ± 8.0 kg), all scholarship NCAA Division I basketball players, volunteered for this study. Subjects participated in four trials, each consisting of a 40-min basketball game with controlled time-outs for rehydration. During the first trial (DHY) subjects were not allowed to rehydrate, and the total weight lost during the contest was used to determine fluid replenishment during the subsequent three trials. During one trial subjects consumed only water (W), while during the other two trials subjects consumed the AG supplement mixed in water using either a low dose (1 g per 500 ml) (AG1) or high dose (2 g per 500 ml) (AG2) concentration. All data assessed prior to and following each game were converted into a Δ score (Post results - Pre results). All performance data were then analyzed using a one-way repeated measures analysis of variance.
During DHY subjects lost 1.72 ± 0.42 kg (2.3%) of their body mass. No differences in fluid intake (1.55 ± 0.43 L) were seen between rehydration trials. A 12.5% (p = 0.016) difference in basketball shooting performance was noted between DHY and AG1 and an 11.1% (p = 0.029) difference was seen between AG1 and W. Visual reaction time was significantly greater following AG1 (p = 0.014) compared to DHY. Differences (p = 0.045) in fatigue, as determined by player loads, were seen only between AG2 and DHY. No differences were seen in peak or mean vertical jump power during any trial.
Rehydration with AG appears to maintain basketball skill performance and visual reaction time to a greater extent than water only.
The observation that muscular exercise is associated with oxidative stress in humans was first reported over 30 years ago. Since this initial report, numerous studies have confirmed that prolonged or high-intensity exercise results in oxidative damage to macromolecules in both blood and skeletal muscle. Although the primary tissue(s) responsible for reactive oxygen species (ROS) production during exercise remains a topic of debate, compelling evidence indicates that muscular activity promotes oxidant production in contracting skeletal muscle fibers. Mitochondria, NADPH oxidase, PLA₂-dependent processes, and xanthine oxidase have all been postulated to contribute to contraction-induced ROS production in muscle but the primary site of contraction-induced ROS production in muscle fibers remains unclear. Nonetheless, contraction-induced ROS generation has been shown to play an important physiological function in the regulation of both muscle force production and contraction-induced adaptive responses of muscle fibers to exercise training. Although knowledge in the field of exercise and oxidative stress has grown markedly during the past 30 years, this area continues to expand and there is much more to be learned about the role of ROS as signaling molecules in skeletal muscle.
The effect of acute L-alanyl-L-glutamine (AG; Sustamine) ingestion on performance changes and markers of fluid regulation, immune, inflammatory, oxidative stress, and recovery was examined in response to exhaustive endurance exercise, during and in the absence of dehydration.
Ten physically active males (20.8 +/- 0.6 y; 176.8 +/- 7.2 cm; 77.4 +/- 10.5 kg; 12.3 +/- 4.6% body fat) volunteered to participate in this study. During the first visit (T1) subjects reported to the laboratory in a euhydrated state to provide a baseline (BL) blood draw and perform a maximal exercise test. In the four subsequent randomly ordered trials, subjects dehydrated to -2.5% of their baseline body mass. For T2, subjects achieved their goal weight and were not rehydrated. During T3 - T5, subjects reached their goal weight and then rehydrated to 1.5% of their baseline body mass by drinking either water (T3) or two different doses (T4 and T5) of the AG supplement (0.05 g.kg-1 and 0.2 g.kg-1, respectively). Subjects then exercised at a workload that elicited 75% of their VO2 max on a cycle ergometer. During T2 - T5 blood draws occurred once goal body mass was achieved (DHY), immediately prior to the exercise stress (RHY), and immediately following the exercise protocol (IP). Resting 24 hour (24P) blood samples were also obtained. Blood samples were analyzed for glutamine, potassium, sodium, aldosterone, arginine vasopressin (AVP), C-reactive protein (CRP), interleukin-6 (IL-6), malondialdehyde (MDA), testosterone, cortisol, ACTH, growth hormone and creatine kinase. Statistical evaluation of performance, hormonal and biochemical changes was accomplished using a repeated measures analysis of variance.
Glutamine concentrations for T5 were significantly higher at RHY and IP than T2 - T4. When examining performance changes (difference between T2 - T5 and T1), significantly greater times to exhaustion occurred during T4 (130.2 +/- 340.2 sec) and T5 (157.4 +/- 263.1 sec) compared to T2 (455.6 +/- 245.0 sec). Plasma sodium concentrations were greater (p < 0.05) at RHY and IP for T2 than all other trials. Aldosterone concentrations at RHY and IP were significantly lower than that at BL and DHY. AVP was significantly elevated at DHY, RHY and IP compared to BL measures. No significant differences were observed between trials in CRP, IL-6, MDA, or in any of the other hormonal or biochemical measures.
Results demonstrate that AG supplementation provided a significant ergogenic benefit by increasing time to exhaustion during a mild hydration stress. This ergogenic effect was likely mediated by an enhanced fluid and electrolyte uptake.
Muscle soreness and decreased performance often follow a bout of high-intensity exercise. By reducing these effects, an athlete can train more frequently and increase long-term performance. The purpose of this study is to examine whether a high-potency, black tea extract (BTE) alters the delayed onset muscle soreness (DOMS), oxidative stress, inflammation, and cortisol (CORT) responses to high-intensity anaerobic exercise.
College-age males (N = 18) with 1+ yrs of weight training experience completed a double-blind, placebo-controlled, crossover study. Subjects consumed the BTE (1,760 mg BTE.d-1) or placebo (PLA) for 9 days. Each subject completed two testing sessions (T1 & T2), which occurred on day 7 of the intervention. T1 & T2 consisted of a 30 s Wingate Test plus eight 10 s intervals. Blood samples were obtained before, 0, 30 & 60 min following the interval sessions and were used to analyze the total to oxidized glutathione ratio (GSH:GSSG), 8-isoprostane (8-iso), CORT, and interleukin 6 (IL-6) secretion. DOMS was recorded at 24 & 48 h post-test using a visual analog scale while BTE or PLA continued to be administered. Significance was set at P < 0.05.
Compared to PLA, BTE produced significantly higher average peak power (P = 0.013) and higher average mean power (P = 0.067) across nine WAnT intervals. BTE produced significantly lower DOMS compared to PLA at 24 h post test (P < 0.001) and 48 h post test (P < 0.001). Compared to PLA, BTE had a slightly higher GSH:GSSG ratio at baseline which became significantly higher at 30 and 60 min post test (P < 0.002). AUC analysis revealed BTE to elicit significantly lower GSSG secretion (P = 0.009), significantly higher GSH:GSSG ratio (P = 0.001), and lower CORT secretion (P = 0.078) than PLA. AUC analysis did not reveal a significant difference in total IL-6 response (P = 0.145) between conditions.
Consumption of theaflavin-enriched black tea extract led to improved recovery and a reduction in oxidative stress and DOMS responses to acute anaerobic intervals. An improved rate of recovery can benefit all individuals engaging in high intensity, anaerobic exercise as it facilitates increased frequency of exercise.
Glutamine and leucine are abundant constituents of plant and animal proteins, whereas the content of arginine in foods and physiological fluids varies greatly. Besides their role in protein synthesis, these three amino acids individually activate signaling pathway to promote protein synthesis and possibly inhibit autophagy-mediated protein degradation in intestinal epithelial cells. In addition, glutamine and arginine stimulate the mitogen-activated protein kinase and mammalian target of rapamycin (mTOR)/p70 (s6) kinase pathways, respectively, to enhance mucosal cell migration and restitution. Moreover, through the nitric oxide-dependent cGMP signaling cascade, arginine regulates multiple physiological events in the intestine that are beneficial for cell homeostasis and survival. Available evidence from both in vitro and in vivo animal studies shows that glutamine and arginine promote cell proliferation and exert differential cytoprotective effects in response to nutrient deprivation, oxidative injury, stress, and immunological challenge. Additionally, when nitric oxide is available, leucine increases the migration of intestinal cells. Therefore, through cellular signaling mechanisms, arginine, glutamine, and leucine play crucial roles in intestinal growth, integrity, and function.
The effect of fatigue as a result of a standard submaximal dynamic exercise on maximal short-term power output generated at different contraction velocities was studied in humans. Six subjects performed 25-s maximal efforts on an isokinetic cycle ergometer at five different pedaling rates (60, 75, 90, 105, and 120 rpm). Measurements of maximal power output were made under control conditions [after 6 min of cycling at 30% maximal O2 uptake (VO2max)] and after fatiguing exercise that consisted of 6 min of cycling at 90% VO2max with a pedaling rate of 90 rpm. Compared with control values, maximal peak power measured after fatiguing exercise was significantly reduced by 23 +/- 19, 28 +/- 11, and 25 +/- 11% at pedaling rates of 90, 105, and 120 rpm, respectively. Reductions in maximum peak power of 11 +/- 8 and 14 +/- 8% at 60 and 75 rpm, respectively, were not significant. The rate of decline in peak power during the 25-s control measurement was least at 60 rpm (5.1 +/- 2.3 W/s) and greatest at 120 rpm (26.3 +/- 13.9 W/s). After fatiguing exercise, the rate of decline in peak power at pedaling rates of 105 and 120 rpm decreased significantly from 21.5 +/- 9.0 and 26.3 +/- 13.9 W/s to 10.0 +/- 7.3 and 13.3 +/- 6.9 W/s, respectively. These experiments indicate that fatigue induced by submaximal dynamic exercise results in a velocity-dependent effect on muscle power. It is suggested that the reduced maximal power at the higher velocities was due to a selective effect of fatigue on the faster fatigue-sensitive fibers of the active muscle mass.
The role of glutamine as a possible ergogenic aid has not been posited in the scientific literature. Although there is an abundance of clinical evidence supporting the need for exogenous glutamine in the maintenance of muscle protein mass and immune system function in critically ill patients, little work has been done that examines the potential utility of glutamine for athletes engaged in heavy exercise training. This brief review will describe a number of studies on the effects of glutamine supplementation on muscle protein mass, immune system function, and glucose regulation. Based on the available clinical evidence, we would speculate that glutamine has potential utility as a dietary supplement for athletes engaged in heavy exercise training.
The purpose of this study was to determine the efficacy of glutamine in promoting whole body carbohydrate storage and muscle glycogen resynthesis during recovery from exhaustive exercise. Postabsorptive subjects completed a glycogen-depleting exercise protocol, then consumed 330 ml of one of three drinks, 18.5% (wt/vol) glucose polymer solution, 8 g glutamine in 330 ml glucose polymer solution, or 8 g glutamine in 330 ml placebo, and also received a primed constant infusion of [1-13C]glucose for 2 h. Plasma glutamine concentration was increased after consumption of the glutamine drinks (0.7-1.1 mM, P < 0.05). In the second hour of recovery, whole body nonoxidative glucose disposal was increased by 25% after consumption of glutamine in addition to the glucose polymer (4.48 +/- 0.61 vs. 3.59 +/- 0.18 mmol/kg, P < 0.05). Oral glutamine alone promoted storage of muscle glycogen to an extent similar to oral glucose polymer. Ingestion of glutamine and glucose polymer together promoted the storage of carbohydrate outside of skeletal muscle, the most feasible site being the liver.
Post-exercise muscle soreness is a dull, aching sensation that follows unaccustomed muscular exertion. Primarily on the basis of previous laboratory-based research on eccentric exercise, soreness is usually said to follow an inverted U-shaped curve over time, peaking 24 - 48 hours after exercise. As such, it is often described as "delayed-onset" muscle soreness. In a study of long-distance runners, soreness seemed to peak immediately and then reduce gradually over time. The study is a secondary analysis of clinical trial data that aims to determine whether the time course of soreness following a natural exercise, long-distance running, is different from that following a laboratory-based exercise, bench-stepping.
This is a reanalysis of data from three previous clinical trials. The trials included 400 runners taking part in long-distance races and 82 untrained volunteers performing a bench-stepping test. Subjects completed a Likert scale of muscle soreness every morning and evening for the five days following their exercise.
Interaction between trial and time is highly significant, suggesting a different time course of soreness following running and bench-stepping. 45% of subjects in the bench-stepping trial experienced peak soreness at the third or fourth follow-up (approximately 36 - 48 hours after exercise) compared to only 14% of those in the running trial. The difference between groups is robust to multivariate analysis incorporating possible confounding variables.
Soreness in runners following long-distance running follows a different time course to that in untrained individuals undertaking bench-stepping. Research on exercise taking place in the laboratory context does not necessarily generalize to exercise undertaken by trained athletes when engaged in their chosen sport.
The aim of this study was to evaluate the effects of severe acute hypoxia on exercise performance and metabolism during 30-s Wingate tests. Five endurance- (E) and five sprint- (S) trained track cyclists from the Spanish National Team performed 30-s Wingate tests in normoxia and hypoxia (inspired O(2) fraction = 0.10). Oxygen deficit was estimated from submaximal cycling economy tests by use of a nonlinear model. E cyclists showed higher maximal O(2) uptake than S (72 +/- 1 and 62 +/- 2 ml x kg(-1) x min(-1), P < 0.05). S cyclists achieved higher peak and mean power output, and 33% larger oxygen deficit than E (P < 0.05). During the Wingate test in normoxia, S relied more on anaerobic energy sources than E (P < 0.05); however, S showed a larger fatigue index in both conditions (P < 0.05). Compared with normoxia, hypoxia lowered O(2) uptake by 16% in E and S (P < 0.05). Peak power output, fatigue index, and exercise femoral vein blood lactate concentration were not altered by hypoxia in any group. Endurance cyclists, unlike S, maintained their mean power output in hypoxia by increasing their anaerobic energy production, as shown by 7% greater oxygen deficit and 11% higher postexercise lactate concentration. In conclusion, performance during 30-s Wingate tests in severe acute hypoxia is maintained or barely reduced owing to the enhancement of the anaerobic energy release. The effect of severe acute hypoxia on supramaximal exercise performance depends on training background.
Critically-ill patients experience an extent of hyperinflammation, cellular immune dysfunction, oxidative stress and mitochondrial dysfunction. Supplementation with key nutrients, such as glutamine and antioxidants, is most likely to have a favourable effect on these physiological derangements, leading to an improvement in clinical outcomes. The results of two meta-analyses suggest that glutamine and antioxidants may be associated with improved survival. The purpose of the present paper is to report the background rationale and study protocol for the evaluation of the effect of high-dose glutamine and antioxidant supplementation on mortality in a large-scale randomized trial in 1200 mechanically-ventilated, critically-ill patients. Patients admitted to an intensive care unit (ICU) with clinical evidence of severe organ dysfunction will be randomized to one of four treatments in a 2 x 2 factorial design: (1) glutamine; (2) antioxidant therapy; (3) glutamine and antioxidant therapy; (4) placebo. The primary outcome for this study is 28 d mortality. The secondary outcomes are duration of stay in ICU, adjudicated diagnosis of infection, multiple organ dysfunction, duration of mechanical ventilation, length of stay in hospital and health-related quality of life at 3 and 6 months. A novel design feature is the combined use of parenteral and enteral study nutrients dissociated from the nutrition support. The therapeutic strategies tested in the randomized trial may lead to less morbidity and improved survival in critically-ill patients. The trial will be conducted in approximately twenty tertiary-care ICU in Canada and the first results are expected in 2009.
Recovery of force and stretch reflex from exhaustive stretch-shortening cycle (SSC) exercise is usually bimodal, characterized as immediate exercise-induced performance reduction, with its quick recovery followed by a longer-lasting reduction in performance. A clear parallel exists between the respective changes in performance, neural activation, and metabolic or structural exercise-induced changes. This implies the existence of potential coupling between muscle failure and the induced neural adjustments that take place along its recovery. The present study was designed to explore the evidence of this coupling more thoroughly.
H- and stretch reflexes were measured before and periodically after exhaustive SSC exercise in human subjects. Several markers of muscle damage and inflammation were also measured during the 8-d postexercise follow-up period.
The results indicate that acute changes of H- and stretch reflex patterns and maximal isometric force are associated with significant increases in lactate, interleukin 6, and prostaglandin E2 concentrations. The delayed changes in reflexes and isometric force occurred concomitantly with increases in muscle thickness, C reactive protein, and substance P concentrations and also in serum creatine kinase activity.
The immediate postexercise decreases in H- and stretch reflexes are probably partially caused by activation of group III and IV afferent fibers by high lactate concentration in combination with possible increases in potassium outflow. Both of these parameters recovered quickly (i.e., 2 h after exercise). The events after the 2-h postexercise point are very likely to be related to muscle damage and associated inflammation. Group III and IV afferent fibers are probably reactivated during this period by mechanical factors.
This article reviews work we have carried out to investigate (1) the transport mechanism responsible for the high distribution ratio of free glutamine commonly observed in skeletal muscle; (2) the fall in the distribution ratio that accompanies starvation, injury and chronic disease, whether directly involving muscle or not; and (3) the effect of modulation of intracellular free-glutamine concentration on protein synthesis and breakdown in skeletal muscle. We suggest that the results are consistent with the controlling role of the muscle membrane glutamine-sodium cotransporter in the regulation of the intracellular glutamine pool, the existence of pathophysiological mechanisms for the modulation of intramuscular glutamine and anabolic effects of glutamine in promoting protein synthesis, with a smaller effect in reducing protein breakdown. The mechanisms by which glutamine effects skeletal muscle protein turnover, and thus muscle protein balance, and the extent of the net flow of amino acids between the periphery and the viscera are unknown as yet, but the results suggest that modulation of transporter activity may offer the possibility of therapeutic intervention to reduce muscle wasting associated with injury and disease.
Immediate and delayed-onset muscle soreness differ mainly in chronology of presentation. Both conditions share the same quality of pain, eliciting and relieving activities and a varying degree of functional deficits. There is no single mechanism for muscle soreness; instead, it is a culmination of 6 different mechanisms. The developing pathway of DOMS begins with microtrauma to muscles and then surrounding connective tissues. Microtrauma is then followed by an inflammatory process and subsequent shifts of fluid and electrolytes. Throughout the progression of these events, muscle spasms may be present, exacerbating the overall condition. There are a multitude of modalities to manage the associated symptoms of immediate soreness and DOMS. Outcomes of each modality seem to be as diverse as the modalities themselves. The judicious use of NSAIDs and continued exercise are suggested to be the most reliable methods and recommended. This review article and each study cited, however, represent just one part of the clinician's decisionmaking process. Careful affirmation of temporary deficits from muscle soreness is not to be taken lightly, nor is the advisement and medical management of muscle soreness prescribed by the clinician.
This study was undertaken in order to develop norms for the Wingate test for physically active young men and women, and also to compare mean power measures obtained from the Wingate test with those obtained from another similar cycle ergometer test. A total of 112 males and 74 females aged 18 to 28 years comprised the subject pool. Data collected from the Wingate test included mean power for 30 s, peak power for 5 s, and a percent fatigue index. Data from the second test (Katch test) included mean power for both 30 s and 40 s. Percentile norms and descriptive statistics were generated as were multiple regression equations for prediction of mean power between the two different tests. Correlations between the two tests ranged from .66 to .87. Comparisons among data derived from this study and those reported for other athletic groups are also given.
To determine whether glutamine can stimulate human muscle glycogen synthesis, we studied in groups of six subjects the effect after exercise of infusion of glutamine, alanine+glycine, or saline. The subjects cycled for 90 min at 70-140% maximal oxygen consumption to deplete muscle glycogen; then primed constant infusions of glutamine (30 mg/kg; 50 mg.kg-1.h-1) or an isonitrogenous, isoenergetic mixture of alanine+glycine or NaCl (0.9%) were administered. Muscle glutamine remained constant during saline infusion, decreased 18% during alanine+glycine infusion (P < 0.001), but rose 16% during glutamine infusion (P < 0.001). By 2 h after exercise, muscle glycogen concentration had increased more in the glutamine-infused group than in the saline or alanine+glycine controls (+2.8 +/- 0.6, +0.8 +/- 0.4, and +0.9 +/- 0.4 mumol/g wet wt, respectively, P < 0.05, glutamine vs. saline or alanine+glycine). Labeling of glycogen by tracer [U-13C]glucose was similar in glutamine and saline groups, suggesting no effect of glutamine on the fractional rate of blood glucose incorporation into glycogen. The results suggest that, after exercise, increased availability of glutamine promotes muscle glycogen accumulation by mechanisms possibly including diversion of glutamine carbon to glycogen.
There is an increased risk of infections in athletes undertaking prolonged, strenuous exercise. There is also some evidence that cells of the immune system are less able to mount a defence against infections after such exercise. The level of plasma glutamine, an important fuel for cells of the immune system, is decreased in athletes after endurance exercise; this may be partly responsible for the apparent immunosuppression which occurs in these individuals. We monitored levels of infection in more than 200 runners and towers. The levels of infection were lowest in middle-distance runners, and highest in runners after a full or ultramarathon and in elite rowers after intensive training. In the present study, athletes participating in different types of exercise consumed two drinks, containing either glutamine (Group G) or placebo (Group P) immediately after and 2 h after exercise. They subsequently completed questionnaires (n = 151) about the incidence of infections during the 7 days following the exercise. The percentage of athletes reporting no infections was considerably higher in Group G (81%, n = 72) than in Group P (49%, n = 79, p < 0.001).
Athletes undergoing intense, prolonged training or participating in endurance races suffer an increased risk of infection due to apparent immunosuppression. Glutamine is an important fuel for some cells of the immune system and may have specific immunostimulatory effects. The plasma glutamine concentration is lower after prolonged, exhaustive exercise: this may contribute to impairment of the immune system at a time when the athlete may be exposed to opportunistic infections. The effects of feeding glutamine was investigated both at rest in sedentary controls and after exhaustive exercise in middle-distance, marathon and ultra-marathon runners, and elite rowers, in training and competition. Questionnaires established the incidence of infection for 7 d after exercise: infection levels were highest in marathon and ultra-marathon runners, and in elite male rowers after intensive training. Plasma glutamine levels were decreased by approximately 20% 1 h after marathon running. A marked increase in numbers of white blood cells occurred immediately after exhaustive exercise, followed by a decrease in the numbers of lymphocytes. The provision of oral glutamine after exercise appeared to have a beneficial effect on the level of subsequent infections. In addition, the ratio of T-helper/T-suppressor cells appeared to be increased in samples from those who received glutamine, compared with placebo.
L-glutamine (GLN) may have an ergogenic effect during exercise considering its base generating potential. We attempted to determine whether GLN ingestion influences acid-base balance and improves high intensity exercise performance.
Ten trained males performed five exercise bouts on a cycle ergometer at 100% of VO2 peak. The first four bouts were 60 sec in duration, while the fifth bout was continued to fatigue. Each bout was separated by 60 sec of recovery. The exercise bouts were initiated 90 min after ingesting 0.03 g.kg body mass-1 of either GLN or placebo (PLC). Venous blood samples were collected pre-ingestion (PRE-IN), pre-exercise (PRE-EX), and following bouts four (B4) and five (B5) and analyzed for pH, bicarbonate concentration (HCO3), and lactate concentration (La-). Time to fatigue for B5 was used as a performance measure.
pH, [HCO3], and [La-] were not significantly different (p > 0.05) between conditions for PRE-IN, PRE-EX, B4, and B5. Time to fatigue was not significantly different between conditions and averaged 263.4 +/- 24.5 sec and 263.2 +/- 19.4 sec for the GLN and PLC trials, respectively.
These data indicate that acute ingestion of L-glutamine does not enhance either buffering potential or high intensity exercise performance in trained males.
Exercise-induced muscle injury in humans frequently occurs after unaccustomed exercise, particularly if the exercise involves a large amount of eccentric (muscle lengthening) contractions. Direct measures of exercise-induced muscle damage include cellular and subcellular disturbances, particularly Z-line streaming. Several indirectly assessed markers of muscle damage after exercise include increases in T2 signal intensity via magnetic resonance imaging techniques, prolonged decreases in force production measured during both voluntary and electrically stimulated contractions (particularly at low stimulation frequencies), increases in inflammatory markers both within the injured muscle and in the blood, increased appearance of muscle proteins in the blood, and muscular soreness. Although the exact mechanisms to explain these changes have not been delineated, the initial injury is ascribed to mechanical disruption of the fiber, and subsequent damage is linked to inflammatory processes and to changes in excitation-contraction coupling within the muscle. Performance of one bout of eccentric exercise induces an adaptation such that the muscle is less vulnerable to a subsequent bout of eccentric exercise. Although several theories have been proposed to explain this "repeated bout effect," including altered motor unit recruitment, an increase in sarcomeres in series, a blunted inflammatory response, and a reduction in stress-susceptible fibers, there is no general agreement as to its cause. In addition, there is controversy concerning the presence of sex differences in the response of muscle to damage-inducing exercise. In contrast to the animal literature, which clearly shows that females experience less damage than males, research using human studies suggests that there is either no difference between men and women or that women are more prone to exercise-induced muscle damage than are men.
The impetus for the novel Energy Formula (EF) which combines the niacin-bound chromium (III) (0.45%) (NBC), standardized extract of Withania somnifera extracts (10.71%), caffeine (22.76%), D-ribose (10.71%) and selected amino acids such as phenylalanine, taurine and glutamine (55.37%) was based on the knowledge of the cardioprotective potentials of the Withania somnifera extract, caffeine and D-ribose as well as their abilities to increase energy levels and the abilities of amino acids to increase the muscle mass and energy levels. The effect of oral supplementation of EF on the safety, myocardial energy levels and cardioprotective ability were investigated in an ischemic-reperfused myocardium model in both male and female Sprague-Dawley rats over 90 days trial period. At the completion of 90 days, the EF-treated male and female rats gained 9.4% and 3.1% less body weights, respectively, as compared to their corresponding control groups. No significant difference was found in the levels of lipid peroxidation and activities of hepatic Aspartate transaminase, Alanine transaminase and Alkaline phosphatase in EF treatment when compared with control animals. The male and female rat hearts were subjected to 30 min of global ischemia followed by 2 h of reperfusion at 30 and 90 days of EF treatment. Cardiovascular functions including heart rate, coronary flow, aortic flow, dp/dt(max), left ventricular developed pressure (LVDP) and infarct size were monitored. The levels of myocardial adenosine triphosphate (ATP), creatine phosphate (CP), phospho-adenosine monophosphate kinase (p-AMPK) levels, were analyzed at the end of 30 and 90 days of treatment. Significant improvement was observed in all parameters in the EF treatment groups as compared to their corresponding controls. Thus the niacin-bound chromium (III) based energy formula is safe and effective supplement to boost energy levels and cardioprotection.