Comparison of sustained-release and rapid-release ß-alanine formulations on changes in skeletal muscle carnosine and histidine content and isometric performance following a muscle-damaging protocol.

ß-alanine supplementation increases muscle carnosine content and improves anaerobic exercise performance by enhancing intracellular buffering capacity. ß-alanine ingestion in its traditional rapid-release formulation (RR) is associated with the symptoms of paresthesia. A sustained-release formulation (SR) of ß-alanine has been shown to circumvent paresthesia and extend the period of supply to muscle for carnosine synthesis. The purpose of this investigation was to compare 28 days of SR and RR formulations of ß-alanine (6 g day-1) on changes in carnosine content of the vastus lateralis and muscle fatigue. Thirty-nine recreationally active men and women were assigned to one of the three groups: SR, RR, or placebo (PLA). Participants supplementing with SR and RR formulations increased muscle carnosine content by 50.1% (3.87 mmol kg-1ww) and 37.9% (2.62 mmol kg-1ww), respectively. The change in muscle carnosine content in participants consuming SR was significantly different (p = 0.010) from those consuming PLA, but no significant difference was noted between RR and PLA (p = 0.077). Although participants ingesting SR experienced a 16.4% greater increase in muscle carnosine than RR, fatigue during maximal voluntary isometric contractions was significantly attenuated in both SR and RR compared to PLA (p = 0.002 and 0.024, respectively). Symptoms of paresthesia were significantly more frequent in RR compared to SR, the latter of which did not differ from PLA. Results of this study demonstrated that only participants consuming the SR formulation experienced a significant increase in muscle carnosine. Differences in the muscle carnosine response between these formulations may have practical significance for athletic populations in which small changes may have important implications on performance.

Post-resistance exercise ingestion of milk protein attenuates plasma TNFα and TNFr1 expression on monocyte subpopulations.

Attenuating TNFα/TNFr1 signaling in monocytes has been proposed as a means of mitigating inflammation. The purpose of this study was to examine the effects of a milk protein supplement on TNFα and monocyte TNFr1 expression. Ten resistance-trained men (24.7 ± 3.4 years; 90.1 ± 11.3 kg; 176.0 ± 4.9 cm) ingested supplement (SUPP) or placebo (PL) immediately post-exercise in a randomized, cross-over design. Blood samples were obtained at baseline (BL), immediately (IP), 30-min (30P), 1-h (1H), 2-h (2H), and 5-h (5H) post-exercise to assess plasma concentrations of myoglobin; tumor necrosis factor-alpha (TNFα); and expression of tumor necrosis factor receptor 1 (TNFr1) on classical, intermediate, and non-classical monocytes. Magnitude-based inferences were used to provide inferences on the true effects of SUPP compared to PL. Plasma TNFα concentrations were "likely attenuated" (91.6% likelihood effect) from BL to 30P in the SUPP group compared with PL (d = 0.87; mean effect: 2.3 ± 2.4 pg mL-1). TNFr1 expressions on classical (75.9% likelihood effect) and intermediate (93.0% likelihood effect) monocytes were "likely attenuated" from BL to 2H in the SUPP group compared with PL (d = 0.67; mean effect: 510 ± 670 RFU, and d = 1.05; mean effect: 2500 ± 2300 RFU, respectively). TNFr1 expression on non-classical monocytes was "likely attenuated" (77.6% likelihood effect) from BL to 1H in the SUPP group compared with PL (d = 0.69; mean effect: 330 ± 430 RFU). Ingestion of a milk protein supplement immediately post-exercise appears to attenuate both plasma TNFα concentrations and TNFr1 expression on monocyte subpopulations in resistance-trained men.

Comparison of Two ß-Alanine Dosing Protocols on Muscle Carnosine Elevations.

OBJECTIVE: ß-alanine (BA) is a nonproteogenic amino acid that combines with histidine to form carnosine. The amount taken orally in individual doses, however, is limited due to symptoms of paresthesia that are associated with higher doses. The use of a sustained-release formulation has been reported to reduce the symptoms of paresthesia, suggesting that a greater daily dose may be possible. The purpose of the present study was to determine whether increasing the daily dose of BA can result in a similar increase in muscle carnosine in a reduced time. METHODS: Eighteen men and twelve women were randomized into either a placebo (PLC), 6-g BA (6G), or 12-g BA (12G) groups. PLC and 6G were supplemented for 4 weeks, while 12G was supplemented for 2 weeks. A resting blood draw and muscle biopsy were obtained prior to (PRE) and following (POST) supplementation. Plasma and muscle metabolites were measured by high-performance liquid chromatography. The loss in peak torque (ΔPT) was calculated from maximal isometric contractions before and after 250 isokinetic kicks at 180°·sec-1 PRE and POST. RESULTS: Both 12G (p = 0.026) and 6G (p = 0.004) increased muscle carnosine compared to PLC. Plasma histidine was decreased from PRE to POST in 12G compared to PLC (p = 0.002) and 6G (p = 0.001), but no group x time interaction (p = 0.662) was observed for muscle histidine. No differences were observed for any hematological measure (e.g., complete blood counts) or in symptoms of paresthesia among the groups. Although no interaction was noted in ΔPT, a trend (p = 0.073) was observed. CONCLUSION: Results of this investigation indicate that a BA supplementation protocol of 12 g/d-1, using a sustained-release formulation, can accelerate the increase in carnosine content in skeletal muscle while attenuating paresthesia.

Comparison of the recovery response from high-intensity and high-volume resistance exercise in trained men.

PURPOSE: The purpose of this study was to compare the physiological responses of a high-volume (HV; 8 sets of 10 repetitions) versus high-intensity (HI; 8 sets of 3 repetitions) exercise protocol in resistance-trained men. METHODS: Twelve men (24.5 ± 4.2 years; 82.3 ± 8.4 kg; 175.2 ± 5.5 cm) with 6.3 ± 3.4 years of resistance training experience performed each protocol in a counterbalanced, randomized order. Performance [counter movement jump peak power (CMJP), isokinetic (ISOK) and isometric leg extension (MVIC), isometric mid-thigh pull (IMTP), and isometric squat (ISQ)] and muscle morphological [cross-sectional area (CSA) of vastus lateralis] assessments were performed at baseline (BL), 30-min (P-30 min), 24-h (P-24 h), 48-h (P-48 h), and 72-h (P-72 h) post-exercise for each testing session. In addition, endocrine (testosterone and cortisol), inflammatory [interleukin-6 (IL-6) and C-reactive protein (CRP)], and markers of muscle damage [creatine kinase (CK), lactate dehydrogenase (LDH), and myoglobin (Mb)] were assessed at the same time points. RESULTS: Significantly greater reductions in CMJP (p < 0.001), and peak torque during both ISOK (p = 0.003) and MVIC (p = 0.008) at P-30 min were detected in HV compared to HI protocol. MVIC was still impaired at P-72 h following the HV protocol, while no differences were noted following HI. Markers of muscle damage (LDH, CK, and Mb) were significantly elevated following both HV and HI (p < 0.05), while cortisol and IL-6 concentrations were significantly elevated at P-30 min following HV only (p < 0.001 and p < 0.05, respectively). CONCLUSIONS: Results indicate that high-volume resistance exercise results in greater performance deficits, and a greater extent of muscle damage, than a bout of high-intensity resistance exercise.

Resistance exercise increases intramuscular NF-κb signaling in untrained males.

PURPOSE: The NF-κB signaling pathway regulates multiple cellular processes following exercise stress. This study aims to examine the effects of an acute lower-body resistance exercise protocol and subsequent recovery on intramuscular NF-κB signaling. METHODS: Twenty-eight untrained males were assigned to either a control (CON; n = 11) or exercise group (EX; n = 17) and completed a lower-body resistance exercise protocol consisting of the back squat, leg press, and leg extension exercises. Skeletal muscle microbiopsies were obtained from the vastus lateralis pre-exercise (PRE), 1-hour (1H), 5-hours (5H), and 48-hours (48H) post-resistance exercise. Multiplex signaling assay kits (EMD Millipore, Billerica, MA, USA) were used to quantify the total protein (TNFR1, c-Myc) or phosphorylation status of proteins belonging to the NF-κB signaling pathway (IKKa/b, IkBα, NF-κB) using multiplex protein assay. Repeated measures ANOVA analysis was used to determine the effects of the exercise bout on intramuscular signaling at each time point. Additionally, change scores were analyzed by magnitude based inferences to determine a mechanistic interpretation. RESULTS: Repeated measures ANOVA indicated a trend for a two-way interaction between the EX and CON Group (p = 0.064) for c-Myc post resistance exercise. Magnitude based inference analysis suggest a "Very Likely" increase in total c-Myc from PRE-5H and a "Likely" increase in IkBα phosphorylation from PRE-5H post-resistance exercise. CONCLUSION: Results indicated that c-Myc transcription factor is elevated following acute intense resistance exercise in untrained males. Future studies should examine the role that post-resistance exercise NF-κß signaling plays in c-Myc induction, ribosome biogenesis and skeletal muscle regeneration.

Intramuscular MAPK signaling following high volume and high intensity resistance exercise protocols in trained men.

PURPOSE: To examine the mitogen-activated protein kinase (MAPK) family of signaling proteins following typical high volume (HV) and high intensity (HI) lower body resistance exercise protocols in resistance-trained men. METHODS: Ten resistance-trained men (24.7 ± 3.4 year; 90.1 ± 11.3 kg; 176.0 ± 4.9 cm) performed each resistance exercise protocol in a random, counterbalanced order. The HV protocol utilized a load of 70 % 1-RM for sets of 10-12 repetitions with a 1-min rest period length between sets and exercises. The HI protocol utilized a load of 90 % 1-RM for sets of 3-5 repetitions with a 3-min rest period length between sets and exercises. Both protocols included six sets of barbell back squats and four sets of bilateral leg press, bilateral hamstring curls, bilateral leg extensions, and seated calf raises. Fine needle muscle biopsies of the vastus lateralis were completed at baseline (BL) and 1-h post exercise (1H). RESULTS: No significant differences over time were noted for phosphorylation of MEK1, ERK1/2, p38, MSK1, ATF2, p53, or c-Jun (p > 0.05). No significance between trial interactions was noted for phosphorylation of MAPK signaling proteins, including MEK1, ERK1/2, p38, JNK, MSK1, ATF2, STAT1, p53, c-Jun, or HSP27 (p > 0.05). However, significant time effects were observed for phosphorylation of JNK (p < 0.01), HSP27 (p < 0.01), and STAT1 (p = 0.03). Phosphorylation of JNK, HSP27, and STAT1 was significantly elevated from BL at 1H for both HV and HI. CONCLUSIONS: HV and HI lower body resistance exercise protocols appear to elicit similar MAPK activation in resistance-trained men.

C-terminal agrin fragment is inversely related to neuromuscular fatigue in older men.

INTRODUCTION: The aim of this study was to examine the relationship between serum C-terminal agrin fragment (CAF) concentrations and neuromuscular fatigue in older adults. METHODS: Twenty-two healthy older men and women volunteered for this study. Resting fasted blood samples were collected and prepared for measurement of serum CAF concentration by a commercially available ELISA kit. The onset of neuromuscular fatigue was measured by monitoring electromyographic fatigue curves from the vastus lateralis muscle using the physical working capacity at fatigue threshold (PWCFT ) test. RESULTS: A significant inverse correlation for men was observed between CAF and PWCFT (r = -0.602; P = 0.05), but not for women (r = 0.208; P = 0.54). After controlling for age and body mass index, significant correlations (r = -0.69; P = 0.042) remained for men, but not for women (r = 0.12; P = 0.76). CONCLUSIONS: These data suggest that serum CAF concentrations were significantly related to the onset of neuromuscular fatigue independent of age and BMI in men only.

Effects of time-release caffeine containing supplement on metabolic rate, glycerol concentration and performance.

This study compared caffeine pharmacokinetics, glycerol concentrations, metabolic rate, and performance measures following ingestion of a time-release caffeine containing supplement (TR-CAF) versus a regular caffeine capsule (CAF) and a placebo (PL). Following a double-blind, placebo-controlled, randomized, cross-over design, ten males (25.9 ± 3.2 y) who regularly consume caffeine ingested capsules containing either TR-CAF, CAF, or PL. Blood draws and performance measures occurred at every hour over an 8-hour period. Plasma caffeine concentrations were significantly greater (p < 0.05) in CAF compared to TR-CAF during hours 2-5 and significantly greater (p = 0.042) in TR-CAF compared to CAF at hour 8. There were no significant differences between trials in glycerol concentrations (p = 0.86) or metabolic measures (p = 0.17-0.91). Physical reaction time was significantly improved for CAF at hour 5 (p=0.01) compared to PL. Average upper body reaction time was significantly improved for CAF and TR-CAF during hours 1-4 (p = 0.04 and p = 0.01, respectively) and over the 8-hour period (p = 0.04 and p = 0.001, respectively) compared to PL. Average upper body reaction time was also significantly improved for TR-CAF compared to PL during hours 5-8 (p = 0.004). TR-CAF and CAF showed distinct pharmacokinetics yielding modest effects on reaction time, yet did not alter glycerol concentration, metabolic measures, or other performance measures. Key pointsTime-release caffeine and regular caffeine showed distinct pharmacokinetics over an 8-hour period following ingestion.Time-release caffeine and regular caffeine yielded modest effects on reaction time over an 8-hour period following ingestion.Time-release caffeine and regular caffeine did not alter glycerol concentration, metabolic measures, or other performance measures over an 8-hour period following ingestion.

Effects of ß-hydroxy-ß-methylbutyrate free acid and cold water immersion on post-exercise markers of muscle damage.

The aim of the current study was to examine the effects of cold water immersion (CWI) with and without the free acid form of ß-hydroxy-ß-methylbutyrate (HMB-FA) on markers of muscle damage following acute lower body resistance exercise. Forty recreationally resistance-trained men (22.3 ± 2.4 years) were randomly divided into one of the four groups: (1) Placebo (PL); (2) HMB-FA; (3) HMB-FA-CWI; (4) PL-CWI. HMB-FA groups ingested 3 g day(-1) and CWI groups submersed their lower body into 10-12 °C water for 10-min post-exercise. No differences between groups were observed for CK; however, PL-CWI had significantly greater elevations in myoglobin 30-min post-exercise compared to HMB-FA (p = 0.009) and PL (p = 0.005), and HMB-FA-CWI was significantly greater than HMB-FA (p = 0.046) and PL (p = 0.028). No differences between groups were observed for IL-6 and IL-10, although CRP was significantly greater 24-h post-exercise for PL-CWI compared to HMB-FA-CWI (p = 0.02) and HMB-FA (p = 0.046). Only HMB-FA-CWI showed significantly (p = 0.02) greater improvements in average power per repetition. CWI appeared to elevate myoglobin compared to other groups, while HMB-FA may have attenuated the increase in CRP when combined with CWI. Nevertheless, HMB-FA or CWI treatments did not appear to provide benefit over PL for recovery. Instead, the combination of CWI and HMB-FA improved performance recovery compared to other groups.

Muscle architecture and strength: adaptations to short-term resistance training in older adults.

INTRODUCTION: Muscle morphology and architecture changes in response to 6 weeks of progressive resistance training were examined in healthy older adults. METHODS: In this randomized, controlled design, muscle strength, quality, and architecture were evaluated with knee extension, DEXA, and ultrasound, respectively, in 25 older adults. RESULTS: Resistance training resulted in significant increases in strength and muscle quality of 32% and 31%, respectively. Cross-sectional area of the vastus lateralis increased by 7.4% (p ≤ 0.05). Physiological cross-sectional area (PCSA) of the thigh, a composite measure of muscle architecture, was related significantly to strength (r = 0.57; p ≤ 0.01) and demonstrated a significant interaction after training (p ≤ 0.05). Change in PCSA of the vastus lateralis was associated with change in strength independent of any other measure. CONCLUSIONS: Six weeks of resistance training was effective at increasing strength, muscle quality, and muscle morphology in older adult men and women.

Current evidence on mesenchymal stem cells for hip osteoarthritis: a narrative review.

There are limited data on the use of mesenchymal stem cell injections for hip osteoarthritis. The goal of this study was to evaluate the literature by analyzing outcomes and comparing methodologies. Online search of PubMed, SportsDiscus and Case Reports Keywords was completed using the keywords 'stem cells' and 'hip' and 'osteoarthritis'. Six studies met the inclusion and exclusion criteria. Five out the six studies had statistically significant improvement in patient reported outcomes after mesenchymal stem cell injections. Only two studies provided information on radiological changes and findings were positive. None of the studies reported major complications. Small series of non-randomized controlled trials completed to date in the use of mesenchymal stem cells for the treatment of hip osteoarthritis reported the procedures to be safe and provide a positive clinical response. Randomized controlled trials must be performed to further confirm mesenchymal stem cells as a treatment option for hip osteoarthritis.

Making prudent recommendations for return-to-play in adult athletes with cardiac conditions.

Clinicians who treat millions of adult athletes throughout the world may be faced with participation or return-to-play decisions in individuals with known or suspected cardiac conditions. Here we review existing published participation guidelines and analyze emerging data from ongoing registries and population-based studies pertaining to return-to-play decisions for cardiac conditions specifically affecting adult athletes. Considerations related to return-to-play decisions will vary according to age of the athlete, with inherited disorders being the main consideration in younger adult athletes aged 18 to 40 yr, and coronary artery disease being the main consideration in older adult athletes aged 40 yr and older. Although this arbitrary division is based on the epidemiology of underlying heart disease in these populations, the essential return-to-play decision process for both age groups is quite similar. Among the most widely used guidelines to make return-to-play decisions in this group of athletes are the 36th Bethesda Conference Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities. These have long been considered the "gold standard" for determining return-to-play decisions in young athletes in the United States. Other guidelines are available for unique purposes, including The European Society of Cardiology guidelines, and the American Heart Association published recommendations regarding participation of young patients (younger than 40 yr) with genetic cardiovascular diseases in recreational sports. The latter are consistent with the 36th Bethesda guidelines and cover common genetically based diseases such as inherited cardiomyopathies, channelopathy, and connective tissue disorders like Marfan's syndrome. The consensus on masters athletes (older than 40 yr) provides return-to-play decisions for a wide variety of conditioned states, from elite older athletes to walk-up athletes. For any adult athlete with a cardiac condition, return-to-play decisions following use of medications, ablation procedures, device implantation, corrective surgery, or coronary intervention depend on whether the procedure has sufficiently altered the risk for sudden cardiac events, and whether there is a potential for unfavorable interaction with cardiac performance.

Hypertension update and cardiovascular risk reduction in physically active individuals and athletes.

Hypertension is a prevalent disease worldwide. Its inadequate treatment leads to major cardiovascular complications, such as myocardial infarction, stroke, and heart failure. These conditions decrease life expectancy and are a substantial cost burden to health care systems. Physically active individuals and professional athletes are not risk free for developing this condition. Although the percentage of persons affected is substantially lower than the general population, these individuals still need to be thoroughly evaluated and blood pressure targets monitored to allow safe competitive sports participation. Regarding treatment, lifestyle modification measures should be routinely emphasized to athletes and active individuals with the same importance as for the general population. Medication treatment can be complicated because of restrictions by athletic organizations and possible limitations on maximal exercise performance. In addition, the choice of an antihypertensive drug should be made with consideration for salt and water losses that routinely occur in athletes, as well as preservation of exercise performance and endothelial function. First-line therapies for athletes and physically active individuals may be different from the general population. Some authorities believe that blocking the renin-angiotensin system with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) is more beneficial compared with diuretics because of ACE inhibitors and ARBs being able to avoid salt and water losses. Dihydropyridine calcium channel blockers (CCBs) are another reasonable choice. Despite effects on heart rate, nondihydropyridine CCBs do not appear to impair exercise performance. beta-Blockers are not used as a first-line therapy in athletes because of effects on exercise and prohibition by the National Collegiate Athletic Association and World Anti-Doping Agency in certain sports. In this article, we address the evidence on hypertension and its related treatments in active individuals to provide recommendations that allow the best competitive sports results and reduce cardiovascular risk.

The validity, reliability and minimal clinically important difference of the patient specific functional scale in snake envenomation.

OBJECTIVE: Valid, reliable, and clinically relevant outcome measures are necessary in clinical studies of snake envenomation. The aim of this study was to evaluate the psychometric (validity and reliability) and clinimetric (minimal clinically important difference [MCID]) properties of the Patient-Specific Functional Scale (PSFS) in snakebite envenomation. METHODS: We performed a secondary analysis of two existing snakebite trials that measured clinical outcomes using the PSFS as well as other quality of life and functional assessments. Data were collected at 3, 7, 10, and 17 days. Reliability was determined using Cronbach's alpha for internal consistency and the intraclass correlation coefficient (ICC) for temporal stability at 10 and 17 days. Validity was assessed using concurrent validity correlating with the other assessments. The MCID was evaluated using the following criteria: (1) the distribution of stable patients according to both standard error of measurement (SEM) and responsiveness techniques, and (2) anchor-based methods to compare between individuals and to detect discriminant ability of a positive change with a receiver operator characteristic (ROC) curve and optimal cutoff point. RESULTS: A total of 86 patients were evaluated in this study. The average PSFS scores were 5.37 (SD 3.23), 7.95 (SD 2.22), and 9.12 (SD 1.37) at 3, 7, and 10 days, respectively. Negligible floor effect was observed (maximum of 8% at 3 days); however, a ceiling effect was observed at 17 days (25%). The PSFS showed good reliability with an internal consistency of 0.91 (Cronbach's alpha) (95% CI 0.88, 0.95) and a temporal stability of 0.83 (ICC) (95% CI 0.72, 0.89). The PSFS showed a strong positive correlation with quality of life and functional assessments. The MCID was approximately 1.0 for all methods. CONCLUSIONS: With an MCID of approximately 1 point, the PSFS is a valid and reliable tool to assess quality of life and functionality in patients with snake envenomation.

Emerging cardiovascular risk factors that account for a significant portion of attributable mortality risk in chronic kidney disease.

Chronic kidney disease (CKD) increases cardiovascular risk and mortality. However, traditional cardiovascular risk factors do not adequately account for the substantial increase in mortality observed in CKD. The aim of this study was to examine the relative contributions of novel cardiovascular risk factors to the risk between CKD and mortality. The study population included 4,680 consecutive new patients from a tertiary care preventive cardiology program from 1996 to 2005. Estimated glomerular filtration rate was calculated using the Modification of Diet in Renal Disease (MDRD) method. Baseline levels of traditional (low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, hypertension, triglycerides, total cholesterol, and fasting glucose) and emerging (apolipoproteins A-I and B, lipoprotein[a], fibrinogen, homocysteine, and high-sensitivity C-reactive protein) risk factors were examined. All-cause mortality was obtained from the Social Security Death Index. There were 278 deaths over a median follow-up period of 22 months. CKD (estimated glomerular filtration rate or=12.5 micromol/L (the top tertile) were associated with a sevenfold greater mortality risk. In conclusion, homocysteine and fibrinogen levels explain nearly 40% of the attributable mortality risk from CKD.

Resistance Exercise Selectively Mobilizes Monocyte Subsets: Role of Polyphenols.

PURPOSE: To examine the impact of polyphenol supplementation on the recruitment, mobilization, and activation of monocyte subsets after resistance exercise. METHODS: Thirty-eight recreationally active males (22.1 ± 3.1 yr; 173.9 ± 7.9 cm; 77.8 ± 14.5 kg) were assigned to 28 d of polyphenol blend (PPB) supplementation, placebo (PL), or control (CON). Blood samples were obtained before (PRE) postresistance exercise, immediately (IP) postresistance exercise, 1 h (1H) postresistance exercise, 5 h (5H) postresistance exercise, 24 h (24H) postresistance exercise, and 48 h (48H) postresistance exercise (PPB/PL) or rest (CON). Fine-needle biopsies were obtained from the vastus lateralis at PRE, 1H, 5H, and 48H. Circulating concentrations of macrophage chemoattractant protein-1 (MCP-1) and fractalkine, as well as intramuscular MCP-1 were analyzed via multiplex assay. Changes in the proportions and expression of CD11b on monocyte subsets were assessed via flow cytometry. RESULTS: Circulating MCP-1 increased in PPB and PL at IP with further increases at 5H. Intramuscular MCP-1 was increased at 1H, 5H, and 48H in all groups. Classical monocyte proportions were reduced in PPB and PL at IP, and increased at 1H. Nonclassical monocytes were increased in PPB and PL at IP, whereas intermediate monocytes were increased at IP, and reduced at 1H. Intermediate monocytes were increased in PPB at 24H and 48H. CD11b expression was reduced on PPB compared with PL and CON at PRE on intermediate and nonclassical monocytes. CONCLUSIONS: Resistance exercise may elicit selective mobilization of intermediate monocytes at 24H and 48H, which may be mediated by tissue damage. Additionally, polyphenol supplementation may suppress CD11b expression on monocyte subsets at rest.

Influence of Skeletal Muscle Carnosine Content on Fatigue during Repeated Resistance Exercise in Recreationally Active Women.

Carnosine is a naturally occurring intramuscular dipeptide that is thought to attenuate fatigue during high-intensity exercise. Carnosine content is influenced by various factors, including gender and diet. Despite research reporting that carnosine content is lower in women compared to men and lower in vegetarians compared to omnivores, no investigations have examined carnosine content in women based on dietary protein intake and its effect on muscle fatigue. Twenty recreationally active women were assigned to either a high (HI; n = 5), moderate (MOD; n = 10), or low (LO; n = 5) group based upon intramuscular carnosine content of the vastus lateralis. Each participant underwent two unilateral maximal voluntary isometric contractions (MVIC) of the knee extensors separated by an isokinetic exercise protocol consisting of five sets of 50 repeated maximal unilateral contractions. Magnitude-based inferences were used to analyze group differences. Percent decline in rate of force development and peak torque (PT) during the MVICs and changes in PT and mean torque during the muscle-fatiguing protocol were lower in HI compared to both MOD and LO. Additionally, absolute and relative dietary protein intake were greater in HI compared to MOD or LO. Results indicated that greater intramuscular carnosine content was reflective of greater dietary protein intake and that individuals with higher carnosine content displayed a greater attenuation of fatigue compared to those with lower carnosine.

ß-Alanine supplementation elevates intramuscular carnosine content and attenuates fatigue in men and women similarly but does not change muscle l-histidine content.

ß-Alanine (BA) supplementation results in elevated intramuscular carnosine content, enhancing buffering capacity during intense exercise. Although men have greater muscle carnosine content than women, elevations still appear to occur despite high baseline levels. Recent research has suggested that BA supplementation may also reduce muscle l-histidine. Thus, the purpose of this investigation was to compare 28 days of BA (6 g·d-1) supplementation in men and women on performance and muscle carnosine, l-histidine, and BA. We hypothesized that supplementation would result in similar elevations in carnosine and performance between sexes and decrease l-histidine. Twenty-six men and women were assigned either BA or placebo (PLA). At baseline, a trend toward greater carnosine (P = .069) was observed in men, and intramuscular BA content was significantly (P ≤ .05) greater in men. Statistical analysis was performed using magnitude-based inferences. Changes in muscle carnosine were likely and very likely greater after BA supplementation compared with PLA in men and women, respectively, but changes were unclear between sexes (mean sex difference: 2.50 ± 4.30 mmol·kg-1 ww). The attenuation of exercise fatigue was likely greater in BA compared with PLA, but the change was unclear between sexes (mean sex difference: 14.0 ± 39.0 Nm). Changes in muscle BA following supplementation was unclear in men, likely elevated in women, but unclear between sexes (mean sex difference: 0.03 ± 0.42 mmol·kg-1 ww). Changes in muscle l-histidine were unclear in men and women, and unclear between sexes (mean sex difference: 0.09 ± 0.13 mmol·kg-1 ww). In conclusion, BA supplementation increased muscle carnosine and attenuated fatigue in men and women similarly but did not reduce muscle l-histidine.

Pyridostigmine reduces QTc interval during recovery from maximal exercise in ischemic heart disease.

Following a randomized, cross-over, and double-blind design, 14 patients with coronary heart disease were submitted, to maximal cardiopulmonary exercise tests on a treadmill, 2 h after the oral administration of either placebo or pyridostigmine bromide (45 mg), a reversible cholinesterase inhibitor. One observer, who was blind to the experimental condition, measured RR and QT intervals over the 12 electrocardiographic leads in the first and third minute of active recovery from exercise. Paired t test was used to compare each variable measured in the same moment after placebo and pyridostigmine. Pyridostigmine reduced the QTc interval in the first minute of active recovery when compared to placebo (P=0.004). Two patients, whose heart rate recovery (1st minute) was below normal values (patient 1=4 bpm; patient 2=7 bpm; i.e. <12 bpm) presented with correction of this variable after pyridostigmine ingestion (patient 1=22 bpm; patient 2=36 bpm). Prospective trials should evaluate the impact of cholinergic stimulation with pyridostigmine on mortality.

A Microbiopsy Method for Immunohistological and Morphological Analysis: A Pilot Study.

INTRODUCTION: The fine aspiration microbiopsy is a relatively new biopsy technique, which allows muscle physiologists to sample skeletal muscle less invasively. However, the small sample size obtained is often deemed insufficient for certain analyses. The aim of the current study was to develop procedures for muscle fiber morphology and immunohistological analysis from a microbiopsy technique. METHODS: Microbiopsies of the vastus lateralis were taken with a 14-gauge microbiopsy needle from four healthy men on two separate occasions. The tissue was oriented in a cryomold, embedded in Tissue-Tek® then frozen in liquid nitrogen cooled isopentane. The muscle sections were stained with hematoxylin and eosin, laminin, MHCI, MHCIIa, and Pax7 for fiber number, mean fiber area, muscle fiber typing, and satellite cell observation. RESULTS: The mean ± SD (range) microbiopsy sample weight was 18.3 ± 2.9 mg (14-22 mg). The mean fiber number within the microbiopsy specimens was 150.4 ± 120.6 (64-366). All viable fibers were measured in each sample, and the mean fiber area was 4385.1 ± 1265.8 µm2 (977.0-10,132.93 µm2). There was no significant time difference (P = 0.69) in mean fiber area. DISCUSSION: Results suggest the potential use of a "minimally invasive" muscle biopsy technique for immunohistological and morphological analysis. This could provide clinicians and investigators additional data in future research. Further investigations are needed to determine the usefulness and potential limiting factors of this technique.