Journal of the International Society of Sports Nutrition - Latest Articles

Oral Rg1 supplementation strengthens antioxidant defense system against exercise-induced oxidative stress in rat skeletal muscles

Szu-Hsien Yu — 2012-05-18T00:00:00Z

Background: Previous studies reported divergent results on nutraceutical actions and free radicalscavenging capability of ginseng extracts. Variations in ginsenoside profile of ginseng due todifferent soil and cultivating season may contribute to the inconsistency. To circumvent thisdrawback, we assessed the effect of major ginsenoside-Rg1 (Rg1) on skeletal muscleantioxidant defense system against exhaustive exercise-induced oxidative stress. Methods: Forty weight-matched rats were evenly divided into control (N = 20) and Rg1 (N = 20)groups. Rg1 was orally administered at the dose of 0.1 mg/kg bodyweight per day for 10-week. After this long-term Rg1 administration, ten rats from each group performed anexhaustive swimming, and remaining rats considered as non-exercise control. Tibialisanterior (TA) muscles were surgically collected immediately after exercise along with nonexerciserats. Results: Exhaustive exercise significantly (p <0.05) increased the lipid peroxidation of control group,evidenced by elevated malondialdehyde (MDA) levels. The increased oxidative stress afterexercise was also confirmed by decreased reduced glutathione to oxidized glutathione ratio(GSH/GSSG ratio) in control rats. However, these changes were completely eliminated inRg1 group. Catalase (CAT) and glutathione peroxidase (GPx) activities were significantly (p<0.05) increased by Rg1 in non-exercise rats, while no significant change after exercise.Nevertheless, glutathione reductase (GR) and glutathione S-transferase (GST) activities weresignificantly increased after exercise in Rg1 group. Conclusions: This study provide compelling evidences that Rg1 supplementation can strengthenantioxidant defense system in skeletal muscle and completely attenuate the membrane lipidperoxidation induced by exhaustive exercise. Our findings suggest that Rg1 can use as anutraceutical supplement to buffer the exhaustive exercise-induced oxidative stress.

Impact of an exercise program on acylcarnitines in obesity: a prospective controlled study

Rene Rodriguez-Gutierrez — 2012-05-10T00:00:00Z

Background: Acylcarnitine (AC) transport dysfunction into the mitochondrial matrix is one of the pathophysiological mechanisms of type 2 diabetes mellitus (DM). The effect of an aerobic exercise (AE) program on this condition in obese subjects without DM is unclear. Methods: A prospective, randomized, longitudinal, interventional study in a University Research Center involved a 10-week AE program in 32 women without DM and a body mass index (BMI) greater than 27 kg/m2. (Cases n = 17; Controls n = 15). The primary objective was to evaluate the influence of a controlled AE program on beta-oxidation according to modifications in short, medium, and long-chain ACs. Secondary objectives were to define the behavior of amino acids, and the correlation between these modifications with metabolic and anthropometric markers. Results: The proportion of dropouts was 17% and 6% in controls and cases, respectively. In cases there was a significant reduction in total carnitine (30.40 [95% CI 28.2 to 35.6]) vs. (29.4 [CI 95% 25.1 to 31.7]) p = 0.0008 and long-chain AC C14 (0.06 [95% CI 0.05 to 0.08]) vs. (0.05 [95% CI 0.05 to 0.09]) p = 0.005 and in C18 (0.31 [95% CI 0.27 to 0.45]) vs. (0.28 [95% CI 0.22 to 0.32]) p = 0.03. Free fatty acid levels remained without change during the study in both groups Conclusion: In conclusion, a controlled 10-week AE program improved beta-oxidation by reducing long-chain ACs. This finding highlights the importance that AE might have in avoiding or reverting lipotoxicity, and in consequence, improving insulin sensitivity and pancreatic beta cell functional reserve.

Dose response effects of a caffeine-containing energy drink on muscle performance: a repeated measures design

Juan Del Coso — 2012-05-08T00:00:00Z

Background: Energy drinks have become the most used caffeine-containing beverages in the sport setting.The aim of this study was to determine the effects of two doses of a caffeine-containingenergy drink on muscle performance during upper- and lower-body power-load tests. Methods: In a randomized order, twelve active participants ingested 1 and 3 mg of caffeine per kg ofbody weight using a commercially available energy drink (Fure(R), ProEnergetics) or the samedrink without caffeine (placebo; 0 mg/kg). After sixty minutes, resting metabolic rate, heartrate and blood pressure were determined. Then, half-squat and bench-press power productionwith loads from 10 to 100% of 1 repetition maximum was determined using a rotatorencoder. Results: In comparison to the placebo, the ingestion of the caffeinated drink increased mean arterialpressure (82 +/- 7 < 88 +/- 8 [almost equal to] 90 +/- 6 mmHg for 0 mg/kg, 1 mg/kg, 3 mg/kg of caffeine,respectively; P < 0.05) and heart rate (57 +/- 7 < 59 +/- 8 < 62 +/- 8 beats/min, respectively; P <0.05) at rest in a dose response manner, though it did not affect resting metabolic rate. Whilethe ingestion of 1 mg/kg of caffeine did not affect maximal power during the power-load testswith respect to the placebo, 3 mg/kg increased maximal power in the half-squat (2554 +/- 167[almost equal to] 2549 +/- 161 < 2726 +/- 167 W, respectively; P < 0.05) and bench-press actions (349 +/- 34 [almost equal to]358 +/- 35 < 375 +/- 33 W, respectively; P < 0.05). Conclusions: A caffeine dose of at least 3 mg/kg in the form of an energy drink is necessary to significantlyimprove half-squat and bench-press maximal muscle power.

Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: a randomized, double-blind, placebo controlled study

Glyn Howatson — 2012-05-08T00:00:00Z

Background: It is well documented that exercise-induced muscle damage (EIMD) decreases musclefunction and causes soreness and discomfort. Branched-chain amino acid (BCAA)supplementation has been shown to increase protein synthesis and decrease muscle proteinbreakdown, however, the effects of BCAAs on recovery from damaging resistance trainingare unclear. Therefore, the aim of this study was to examine the effects of a BCAAsupplementation on markers of muscle damage elicited via a sport specific bout of damagingexercise in trained volunteers. Methods: Twelve males (mean +/- SD age, 23 +/- 2 y; stature, 178.3 +/- 3.6 cm and body mass, 79.6 +/- 8.4 kg)were randomly assigned to a supplement (n = 6) or placebo (n = 6) group. The damagingexercise consisted of 100 consecutive drop-jumps. Creatine kinase (CK), maximal voluntarycontraction (MVC), muscle soreness (DOMS), vertical jump (VJ), thigh circumference (TC)and calf circumference (CC) were measured as markers of muscle damage. All variables weremeasured immediately before the damaging exercise and at 24, 48, 72 and 96 h post-exercise. Results: A significant time effect was seen for all variables. There were significant group effectsshowing a reduction in CK efflux and muscle soreness in the BCAA group compared to theplacebo (P < 0.05). Furthermore, the recovery of MVC was greater in the BCAA group(P < 0.05). The VJ, TC and CC were not different between groups. Conclusion: The present study has shown that BCAA administered before and following damagingresistance exercise reduces indices of muscle damage and accelerates recovery in resistancetrainedmales. It seems likely that BCAA provided greater bioavailablity of substrate toimprove protein synthesis and thereby the extent of secondary muscle damage associatedwith strenuous resistance exercise. Clinical Trial Registration Number: NCT01529281.

Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage

Yanita McLeay — 2012-05-07T00:00:00Z

Background: Exercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress /inflammation which, in the short-term at least, is associated with impaired muscularperformance. Dietary antioxidants have been shown to reduce excessive oxidative stress;however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberriesdemonstrate antioxidant and anti-inflammatory properties. In this study we examine the effectof New Zealand blueberries on EIMD after strenuous eccentric exercise. Methods: In a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo ofa similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hoursafter EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peakand average peak torque across the knee, during concentric, isometric, and eccentric actionswere measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammationwere assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-wayANOVA. Results: A significant (p < 0.001) decrease in isometric, concentric and eccentric torque was observed12 hours following exercise in both treatment groups. During the 60 hour recovery period, asignificant (p = 0.047) interaction effect was seen for peak isometric tension suggesting afaster rate of recovery in the blueberry intervention group. A similar trend was observed forconcentric and eccentric strength. An increase in oxidative stress and inflammatorybiomarkers was also observed in both treatment groups following EIMD. Although a fasterrate of decrease in oxidative stress was observed in the blueberry group, it was not significant(p < 0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase inplasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60hours recovery. Conclusions: This study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMDaccelerates recovery of muscle peak isometric strength. This effect, although independent ofthe beverage's inherent antioxidant capacity, appears to involve an up-regulation of adaptiveprocesses, i.e. endogenous antioxidant processes, activated by the combined actions of theeccentric exercise and blueberry consumption. These findings may benefit the sportingcommunity who should consider dietary interventions that specifically targets health andperformance adaptation.

Beta-hydroxy-beta-methyl-butyrate blunts negative age-related changes in body composition, functionality and myofiber dimensions in rats

Jacob Wilson — 2012-04-18T00:00:00Z

PurposeTo determine the effects of 16 wk. of beta-hydroxy-beta-methylbutyrate (HMB) administration on age-related changes in functionality and diffusion tensor imaging (DTI) determined myofiber dimensions. Methods: Twelve young (44 wk.), 6 middle-aged (60 wk.), 10 old (86 wk.), and 5 very old (102 wk.) male Fisher-344 rat's body composition and grip strength were assessed at baseline. Following, 6 young, 6 middle-aged, 5 old and 5 very old rats were sacrificed for baseline myofiber dimensions and gene transcript factor expression in the soleus (SOL) and gastrocnemius (GAS). The remaining 6 young and 5 old rats were given HMB for 16 wk. and then sacrificed. Results: Fat mass increased in the middle-aged control condition (+49%) but not the middle-aged HMB condition. In addition, fat mass declined (-56%) in the old HMB condition but not the old control condition. Normalized strength declined and maintained respectively in the control and HMB conditions from 44 to 60 wk. and increased (+23%) (p < 0.05) from 86 to 102 wk. in only the HMB condition. Declines occurred in myofiber size in all muscles from 44 to 102 wk. in the control condition(-10 to -15%), but not HMB condition. Atrogin-1 mRNA expression in the SOL and GAS muscles was greater in the 102-wk control condition than all other conditions: SOL (+45%) and GAS (+100%). This elevation was blunted by HMB in the 102 wk. old SOL. There was a condition effect in the SOL for myogenin, which significantly increased (+40%) only in the 102-wk. HMB group relative to the 44-wk. group. Conclusions: HMB may blunt age-related losses of strength and myofiber dimensions, possibly through attenuating the rise in protein breakdown.

Acute L-arginine alpha ketoglutarate supplementation fails to improve muscular performance in resistance trained and untrained men

Benjamin Wax — 2012-04-17T00:00:00Z

Background: Dietary supplements containing L-arginine are marketed to improve exercise performance, but the efficacy of such supplements is not clear. Therefore, this study examined the efficacy of acute ingestion of L-arginine alpha-ketoglutarate (AAKG) muscular strength and endurance in resistance trained and untrained men. Methods: Eight resistance trained and eight untrained healthy males ingested either 3000 mg of AAKG or a placebo 45 minutes prior to a resistance exercise protocol in a randomized, double-blind crossover design. One-repetition maximum (1RM) on the standard barbell bench press and leg press were obtained. Upon determination of 1RM, subjects completed repetitions to failure at 60 % 1RM on both the standard barbell bench press and leg press. Heart rate was measured pre and post exercise. One week later, subjects ingested the other supplement and performed the identical resistance exercise protocol. Results: Our data showed statistical significant differences (p < 0.05) between resistance trained and untrained males for both 1RM and total load volume (TLV; multiply 60 % of 1RM times the number of repetitions to failure) for the upper body. However, 1RM and TLV were not statistically different (p > 0.05) between supplementation conditions for either resistance trained or untrained men in the bench press or leg press exercises. Heart rate was similar at the end of the upper and lower body bouts of resistance exercise with AAKG vs. placebo. Conclusion: The results from our study indicate that acute AAKG supplementation provides no ergogenic benefit on 1RM or TLV as measured by the standard barbell bench press and leg press, regardless of the subjects' training status.

Adenosine 5' -triphosphate (ATP) supplements are not orally bioavailable: a randomized, placebocontrolled cross-over trial in healthy humans

Ilja Arts — 2012-04-17T00:00:00Z

Background: Nutritional supplements designed to increase adenosine 5' -triphosphate (ATP) concentrationsare commonly used by athletes as ergogenic aids. ATP is the primary source of energy for thecells, and supplementation may enhance the ability to maintain high ATP turnover duringhigh-intensity exercise. Oral ATP supplements have beneficial effects in some but not allstudies examining physical performance. One of the remaining questions is whether orallyadministered ATP is bioavailable. We investigated whether acute supplementation with oralATP administered as enteric-coated pellets led to increased concentrations of ATP or itsmetabolites in the circulation. Methods: Eight healthy volunteers participated in a cross-over study. Participants were given in randomorder single doses of 5000 mg ATP or placebo. To prevent degradation of ATP in the acidicenvironment of the stomach, the supplement was administered via two types of pH-sensitive,enteric-coated pellets (targeted at release in the proximal or distal small intestine), or via anaso-duodenal tube. Blood ATP and metabolite concentrations were monitored by HPLC for4.5 h (naso-duodenal tube) or 7 h (pellets) post-administration. Areas under the concentrationvs. time curve were calculated and compared by paired-samples t-tests. Results: ATP concentrations in blood did not increase after ATP supplementation via enteric-coatedpellets or naso-duodenal tube. In contrast, concentrations of the final catabolic product ofATP, uric acid, were significantly increased compared to placebo by ~50% afteradministration via proximal-release pellets (P = 0.003) and naso-duodenal tube (P = 0.001),but not after administration via distal-release pellets. Conclusions: A single dose of orally administered ATP is not bioavailable, and this may explain whyseveral studies did not find ergogenic effects of oral ATP supplementation. On the otherhand, increases in uric acid after release of ATP in the proximal part of the small intestinesuggest that ATP or one of its metabolites is absorbed and metabolized. Uric acid itself mayhave ergogenic effects, but this needs further study. Also, more studies are needed todetermine whether chronic administration of ATP will enhance its oral bioavailability.

Expression profiles of carnosine synthesis-related genes in mice after ingestion of carnosine or SZalanine

Miyaji Takayuki — 2012-04-17T00:00:00Z

Background: Carnosine is a dipeptide that improves exercise performance. The carnosine synthesismechanism through carnosine and SZ-alanine ingestion remains unclear. Therefore, weinvestigated the tissue distribution of carnosine synthase, ATP-grasp domain-containingprotein-1 (ATPGD1) mRNA, and ATPGD1 and carnosine specific dipeptidase (CN1) geneexpression profiles in mice that were given carnosine or SZ-alanine orally. Methods: ddY mice (7-week-old) were randomly divided into three groups (n = 6 to 8 animals pergroup) and were orally given 2 g/kg body weight of carnosine, SZ-alanine, or water. After 15,30, 60, 120, 180, or 360 min of treatment, the tissues (brain, blood, liver, kidneys, olfactorybulbs, hindleg muscles) were collected. The obtained tissues measured the expression ofATPGD1 and CN1 genes using quantitative PCR methods. Results: The ATPGD1 gene was expressed in muscle and to a lesser extent in brain. The expression ofATPGD1 in the vastus lateralis muscle increased significantly at 180 min (P = 0.023) aftercarnosine ingestion and 60 (P = 0.023) and 180 min (P = 0.025) after SZ-alanine ingestion.Moreover, the carnosine group showed a significantly increased renal expression of the CN1gene 60 min after ingestion (P = 0.0015). Conclusions: The ATPGD1 gene showed high expression levels in brain and muscle. The SZ-alanine orcarnosine administration significantly increased ATPGD1 and CN1 expression in mice.

Improved cycling performance with ingestion of hydrolyzed marine protein depends on performance level

Geir Vegge — 2012-04-10T00:00:00Z

Background: The effect on performance of protein ingestion during or after exercise is not clear. This has largely been attributed to the utilization of different scientific protocols and the neglection of accounting for factors such as differences in physical and chemical properties of protein supplements and differences in athletic performance level. Methods: We hypothesized that ingestion of unprocessed whey protein (15.3 g·h-1) together with carbohydrate (60 g·h-1), would provide no ergogenic effect on 5-min mean-power performance following 120 min cycling at 50% of maximal aerobic power (2.8 ± 0.2 W·kg-1, corresponding to 60 ± 4% of VO2max), compared to CHO alone (60 g·h-1). Conversely, we hypothesized that ingestion of the hydrolyzed marine protein supplement NutriPeptin™ (Np, 2.7 g·h-1), a processed protein supplement with potentially beneficial amino acid composition, together with a PROCHO beverage (12.4 g·h-1 and 60 g·h-1, respectively) would provide an ergogenic effect on mean-power performance. We also hypothesized that the magnitude of the ergogenic effect of NpPROCHO would be dependent on athletic performance. As for the latter analysis, performance level was defined according to a performance factor, calculated from individual pre values of Wmax, VO2max and 5-min mean-power performance, wherein the performance of each subject was ranked relative to the superior cyclist whos performance was set to one. Twelve trained male cyclists (VO2max = 65 ± 4 ml·kg-1·min-1) participated in a randomized double-blinded cross-over study.Results and conclusionsOverall, no differences were found in 5-min mean-power performance between either of the beverages (CHO 5.4 ± 0.5 W·kg-1; PROCHO 5.3 ± 0.5 W·kg-1; NpPROCHO 5.4 ± 0.3 W·kg-1) (P = 0.29). A negative correlation was found between NpPROCHO mean-power performance and athletic performance level (using CHO-performance as reference; Pearson R = -0.74, P = 0.006). Moreover, ingestion of NpPROCHO resulted in improved 5-min mean-power performance relative to ingestion of CHO in the six lesser performing subjects compared to the six superior performing subjects (P < 0.05). This suggests that with the current protocol, NpPROCHO provided an ergogenic effect on 5-min mean-power performance in athletes with a lower performance level.