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Extracellular signal-regulated protein kinase 1/2 (ERK1/2) moderates skeletal muscle growth; however, chronic responses of this protein to unique resistance exercise (RE) paradigms are yet to be explored. The purpose of this investigation was to describe the long-term response of ERK1/2 following circuit weight training (CWT), recreationally weight training (WT), powerlifting (PL) and weightlifting (WL). Independent t-tests were used to determine differences in trained groups compared to sedentary controls. Total ERK1/2 content was lower in PL and WL compared to their controls (p ≤ 0.05). Specific trained groups displayed large (WL: pERK/total-ERK; d = 1.25) and moderate (CWT: total ERK1/2; d = 0.54) effect sizes for altered kinase expression compared to controls. The results indicate ERK1/2 expression is down-regulated after chronic RE in well-trained weightlifters and powerlifters. Lower expression of this protein may be a method in which anabolism is tightly regulated after many years of high-intensity RE.

Background: We compared Glycine Propionyl-L-Carnitine (GlycoCarn(R)) and three different pre-workout nutritional supplements on measures of skeletal muscle oxygen saturation (StO2), blood nitrate/nitrite (NOx), lactate (HLa), malondialdehyde (MDA), and exercise performance in men., Methods: Using a randomized, double-blind, cross-over design, 19 resistance trained men performed tests of muscular power (bench press throws) and endurance (10 sets of bench press to muscular failure). A placebo, GlycoCarn(R), or one of three dietary supplements (SUPP1, SUPP2, SUPP3) was consumed prior to exercise, with one week separating conditions. Blood was collected before receiving the condition and immediately after exercise. StO2 was measured during the endurance test using Near Infrared Spectroscopy. Heart rate (HR) and rating of perceived exertion (RPE) were determined at the end of each set., Results: A condition effect was noted for StO2 at the start of exercise (p = 0.02), with GlycoCarn(R) higher than SUPP2. A condition effect was also noted for StO2 at the end of exercise (p = 0.003), with SUPP1 lower than all other conditions. No statistically significant interaction, condition, or time effects were noted for NOx or MDA (p > 0.05); however, MDA decreased 13.7% with GlycoCarn(R) and increased in all other conditions. Only a time effect was noted for HLa (p < 0.0001), with values increasing from pre- to post-exercise. No effects were noted for HR, RPE, or for any exercise performance variables (p > 0.05); however, GlycoCarn(R) resulted in a statistically insignificant greater total volume load compared to the placebo (3.3%), SUPP1 (4.2%), SUPP2 (2.5%), and SUPP3 (4.6%)., Conclusion: None of the products tested resulted in favorable changes in our chosen outcome measures, with the exception of GlycoCarn(R) in terms of higher StO2 at the start of exercise. GlycoCarn(R) resulted in a 13.7% decrease in MDA from pre- to post-exercise and yielded a non-significant but greater total volume load compared to all other conditions. These data indicate that 1) a single ingredient (GlycoCarn(R)) can provide similar practical benefit than finished products containing multiple ingredients, and 2) while we do not have data in relation to post-exercise recovery parameters, the tested products are ineffective in terms of increasing blood flow and improving acute upper body exercise performance.

Correction to Richard J Bloomer, Kelsey H Fisher-Wellman, Kelley G Hammond, Brian K Schilling, Adrianna A Weber and Bradford J Cole: Dietary supplement increases plasma norepinephrine, lipolysis, and metabolic rate in resistance trained men. Journal of the International Society of Sports Nutrition 2009, 6: 4.

Individuals with impaired lipid and glucose metabolism are at increased risk for postprandial oxidative stress. Acute exercise can attenuate the rise in both blood triglyceride (TAG) and glucose, and increase antioxidant enzyme activity after food intake, which may decrease the oxidative stress response. This study investigated the effect of acute exercise on blood TAG and oxidative stress biomarkers in prediabetic women. Sixteen prediabetic women (30 +/- 3 years of age; fasting blood glucose, 107 +/- 3 mg x dL(-1); body mass index, 32 +/- 2 kg x m(-2)) consumed a high-fat meal with and without a session of aerobic exercise 15 minutes preceding the meal (45-minute duration, 65% heart rate reserve), in a random order cross-over design. Blood samples were collected premeal (fasted) and at 1, 2, 4, and 6 hours postmeal and assayed for Trolox equivalent antioxidant capacity (TEAC), xanthine oxidase (XO) activity, hydrogen peroxide (H2O2), malondialdehyde (MDA), TAG, and glucose. No interaction or condition main effects were noted (P > 0.05). However, time main effects were noted for XO, H2O2, MDA, and TAG (P < 0.0001), with values higher from 1 to 6 hours postmeal compared with premeal, and for TEAC (P = 0.05), with values lower at 4 hours postmeal. Glucose remained relatively unchanged (P > 0.05). Acute exercise, performed at the intensity and duration of the present study, does not influence postprandial TAG and oxidative stress in obese prediabetic women. Such individuals may need a greater volume of exercise for measurable effects.

Background: Dietary supplements targeting fat loss and increased thermogenesis are prevalent within the sport nutrition/weight loss market. While some isolated ingredients have been reported to be efficacious when used at high dosages, in particular in animal models and/or via intravenous delivery, little objective evidence is available pertaining to the efficacy of a finished product taken by human subjects in oral form. Moreover, many ingredients function as stimulants, leading to increased hemodynamic responses. The purpose of this investigation was to determine the effects of a finished dietary supplement on plasma catecholamine concentration, markers of lipolysis, metabolic rate, and hemodynamics., Methods: Ten resistance trained men (age = 27 +/- 4 yrs; BMI = 25 +/- 3 kg. m-2; body fat = 9 +/- 3%; mean +/- SD) ingested a dietary supplement (Meltdown(R), Vital Pharmaceuticals) or a placebo, in a random order, double blind cross-over design, with one week separating conditions. Fasting blood samples were collected before, and at 30, 60, and 90 minutes post ingestion and were assayed for epinephrine (EPI), norepinephrine (NE), glycerol, and free fatty acids (FFA). Area under the curve (AUC) was calculated for all variables. Gas samples were collected from 30-60 minutes post ingestion for measurement of metabolic rate. Heart rate and blood pressure were recorded at all blood collection times., Results: AUC was greater for the dietary supplement compared to the placebo for NE (1332 +/- 128 pg.mL-1.90 min-1 vs. 1003 +/- 133 pg.mL-1.90 min-1; p = 0.03), glycerol (44 +/- 3 mug.mL-1.90 min-1 vs. 26 +/- 2 mug.mL-1.90 min-1; p < 0.0001), and FFA (1.24 +/- 0.17 mmol.L-1.90 min-1 vs. 0.88 +/- 0.12 mmol.L-1.90 min-1; p = 0.0003). No difference between conditions was noted for EPI AUC (p > 0.05). For all variables, values were highest at 90 minutes post ingestion. Total kilocalorie expenditure during the 30 minute collection period was 29.6% greater (p = 0.02) for the dietary supplement (35 +/- 3 kcal) compared to placebo (27 +/- 2 kcal). A condition main effect was noted for systolic blood pressure (p = 0.04), with values increasing from 117 +/- 2 mmHg to 123 +/- 2 mmHg with the dietary supplement, while remaining unchanged for placebo. No other hemodynamic changes were noted (p > 0.05)., Conclusion: The dietary supplement results in an acute increase in plasma NE and markers of lipolysis, as well as metabolic rate. This occurs without altering hemodynamic variables in a clinically significant manner. Intervention studies to determine the impact of this dietary supplement on weight/fat loss are warranted.

Background: Both acute bouts of prior exercise (preconditioning) and antioxidant nutrients have been used in an attempt to attenuate muscle injury or oxidative stress in response to resistance exercise. However, most studies have focused on untrained participants rather than on athletes. The purpose of this work was to determine the independent and combined effects of antioxidant supplementation (vitamin C + mixed tocopherols/tocotrienols) and prior eccentric exercise in attenuating markers of skeletal muscle injury and oxidative stress in resistance trained men., Methods: Thirty-six men were randomly assigned to: no prior exercise + placebo; no prior exercise + antioxidant; prior exercise + placebo; prior exercise + antioxidant. Markers of muscle/cell injury (muscle performance, muscle soreness, C-reactive protein, and creatine kinase activity), as well as oxidative stress (blood protein carbonyls and peroxides), were measured before and through 48 hours of exercise recovery., Results: No group by time interactions were noted for any variable (P > 0.05). Time main effects were noted for creatine kinase activity, muscle soreness, maximal isometric force and peak velocity (P < 0.0001). Protein carbonyls and peroxides were relatively unaffected by exercise., Conclusion: There appears to be no independent or combined effect of a prior bout of eccentric exercise or antioxidant supplementation as used here on markers of muscle injury in resistance trained men. Moreover, eccentric exercise as used in the present study results in minimal blood oxidative stress in resistance trained men. Hence, antioxidant supplementation for the purpose of minimizing blood oxidative stress in relation to eccentric exercise appears unnecessary in this population.

The purpose of this study was to determine if supplementation with a liquid multi-vitamin/mineral would improve anaerobic exercise performance. Fourteen resistance-trained men performed a 30-second cycle sprint and one set of squat exercise on 2 separate days before and following 8 weeks of supplementation with either a liquid multi-vitamin/ mineral or a placebo. Heart rate, perceived exertion, blood lactate, peak and mean power, and rate of fatigue were determined for all tests. No differences were noted for any variable (P > 0.05). When controlling for presupplementation values, however, a decreased rate of fatigue was noted for both exercise tests following the multi-vitamin/mineral supplementation. These data suggest that in resistance trained men consuming a nutritionally sound diet, supplementation with a liquid multi-vitamin/mineral does not favorably impact most anaerobic exercise performances. Such supplementation, however, may result in a minor decreased rate of fatigue. It appears that, in terms of improved short duration anaerobic exercise performance, supplemental micronutrients may not be efficient ergogenic agents for well-trained individuals consuming an adequate diet.

Thirty-six healthy men with varying degrees of physical training background performed maximal-effort isometric and isoinertial knee extensor actions, with relative loads equal to 40% and 70% of one-repetition maximum. Force, velocity, and power were derived from force and linear position transducers at 500 Hz. Biopsies were taken from the vastus lateralis and analyzed by SDS-PAGE for relative myosin heavy chain (MHC) content. Relative MHC IIx content was included in a regression model, and explained variance noted. Relative MHC I content was subsequently added to the regression model to determine what, if any, additional variance was explained beyond that of MHC IIx. Results indicated that no relationship (r = 0.0 to 0.1) exists between the relative expression of MHC isoforms from the vastus lateralis and isometric/isoinertial performance in a population with diverse training backgrounds. Lack of nervous system adaptations in the untrained subjects in the study possibly attenuates the significant relationship between MHC and in-vivo muscle performance previously established in trained populations.