Postexercise myogenic gene expression : are human findings lost during translation?

Muscle progenitor cell (MPC) activity is exercise responsive. Post resistance-exercise alterations in myogenic messenger RNAs (mRNAs) found by us and others may initiate these events. However, these mRNA data in the absence of microscopic MPC activity data have limited this interpretation. Alternatively, with our acute exercise data as our basis, we propose that these genes may control other hypertrophic processes in postmitotic fibers

Nutrient timing considerations for the military, aged, metabolically-challenged populations, and children

Nutrient timing considerations for the military, aged, metabolically-challenged populations, and childre

The expression of androgen-regulated genes before and after a resistance exercise bout in younger and older men

Roberts, MD, Dalbo, VJ, Hassell, SE, and Kerksick, CM. The expression of androgen-regulated genes before and after a resistance exercise bout in younger and older men. J Strength Cond Res 23(4): 1060–1067, 2009—This cross-sectional study examined aging and resistance exercise–related changes in intramuscular gene expression in younger (21.3 6 0.6 years, 84.8 6 6.0 kg, 26.6 6 2.1 kg_m22; n = 11) and older men (67.6 6 1.3 years, 88.7 6 4.8 kg, 28.6 6 1.4 kg_m22; n = 13) surrounding a single bout of resistance exercise. Participants completed 3 3 10 repetitions at 80% of their 1 repetition maximum for Smith squat, leg press, and leg extension. Muscle biopsies were obtained before and 24 hours after exercise, whereas venous blood was collected before, immediately after and 24 hours after exercise. Free testosterone levels were greater in younger participants at all time points (p , 0.05), in addition to a greater increase in the younger men immediately post exercise (p , 0.01). Preexercise human growth hormone levels between age groups were similar (p . 0.05). Human growth hormone increased immediately post exercise in both groups (p , 0.05) with a greater response occurring in the younger (p , 0.001) men. Older men expressed greater levels of androgen receptor (AR) at rest (p = 0.02). A significant correlation existed between preexercise free testosterone levels basal AR gene expression (r = 20.59, p , 0.01). These data suggest that AR expression patterns may be related to circulating free testosterone levels. Although these findings do not fully unveil the genomic effects of androgen signaling and its relationship to muscle wasting conditions, these results provide a platform for future researchers seeking to employ gene therapy to remedy muscle loss

Efficacy and safety of a popular thermogenic drink after 28 days of ingestion

Background: We have recently demonstrated that consuming a thermogenic drink (TD) acutely increases energy expenditure and serum markers of lipolysis in healthy, college-aged individuals. The purpose of this study was to determine if consuming TD over 28 days affects its acute thermogenic and lipolytic effects as well as body composition and clinical chemistry safety markers. Methods: Sixty healthy, males (mean ± SE; 23 ± 1 years, 177 ± 2 cm, 81.7 ± 2.1 kg, 22.8 ± 1.4% body fat; n = 30) and females (23 ± 1 years, 166 ± 2 cm, 62.1 ± 1.8 kg, 28.3 ± 1.4% body fat; n = 30) reported to the laboratory on day 0 (T1) for determination of body composition, resting energy expenditure (REE) as well as glycerol and free fatty acid (FFA) levels before and after ingesting either 336 ml of TD or a non-caloric, non-caffeinated placebo (PLA) drink. Following day 0, participants supplemented daily with 336 ml•day-1 of either TD or PLA and repeated identical testing procedures on day 28 (T2). Day 28 area under the curve (AUC) values were calculated for REE, FFA, and glycerol. Day 28 acute data and prolonged AUC comparisons between groups were analyzed using ANOVAs with repeated measures. Results: Percent body fat (p = 0.02) and fat mass (p = 0.01) decreased in the TD group compared to the PLA group after 28 days. Day 28 FFA AUC values (p = 0.048) were greater in the TD group compared to the PLA group. There was no significant difference in day 28 REE AUC values (p = 0.30) or glycerol AUC values (p = 0.21), although a significant increase in REE values in the PLA group may have confounded these findings. There were no differences between groups concerning blood and clinical safety markers. Conclusion: Within-group elevations in FFA and REE values in the TD group were still evident following a 28-day supplementation period which may contribute to the observed decrements in ¿. Further, prolonged TD supplementation did not alter the assessed clinical safety markers. Future studies should examine the synergistic and independent effects of the active ingredients in addition to effects of longer ingestion periods of TD ingestion with or without exercise at promoting and sustaining changes in body composition

Acute effects of ingesting a commercial thermogenic drink on changes in energy expenditure and markers of lipolysis

Background: To determine the acute effects of ingesting a thermogenic drink (Celsius, Delray Beach, FL) (TD) on changes in metabolism and lipolysis. Methods: Healthy college-aged male (23.2 ± 4.0 y, 177.2 ± 6.1 cm, 81.7 ± 11.3 kg, 22.8 ± 7.3 % fat; n = 30) and female (23.4 ± 3.1 y, 165.6 ± 8.7 cm, 62.1 ± 9.9 kg, 28.3 ± 7.4 % fat; n = 30) participants were matched according to height and weight to consume 336 ml of the TD or a noncaloric, non-caffeinated placebo (PLA). After a 12 h fast, participants reported for pre-consumption measures of height, weight, heart rate, blood pressure, resting energy expenditure (REE), respiratory exchange ratio (RER), glycerol and free-fatty acid (FFA) concentrations. REE and RER were determined at 60, 120, and 180 min post-consumption. Serum glycerol and FFA concentrations were determined at 30, 60, 120 and 180 min post-consumption. Results: When compared to PLA, TD significantly increased REE at 60, 120 and 180 min (p < 0.05). FFA concentrations were significantly greater in TD compared to PLA at 30, 60, 120 and 180 min post-consumption (p < 0.05). No between-group differences were found in RER. Conclusion: Acute TD ingestion significantly increased REE, FFA and glycerol appearance. If sustained, these changes may help to promote weight loss and improve body composition; however, these findings are currently unknown as are the general safety and efficacy of prolonged consumption

Aging and sequential resistance exercise bout effects on housekeeping gene messenger RNA expression in human skeletal muscle.

The purpose of this study was to investigate how age and 1 week of conventional resistance exercise affects commonly used housekeeping gene (HKG) messenger RNAs (mRNAs) in skeletal muscle. Ten college-aged (18–25 years) and 10 older (60–76 years) men completed 3 lower-body resistance exercise bouts on Monday, Wednesday, and Friday, and muscle samples were obtained before bout 1 (T1), 48 hours after the first (T2) and second bouts (T3), and 24 hours after the third bout (T4). Raw Ct values indicated that b-actin and cyclophilin were more highly expressed in older vs. younger males (p < 0.01) at T1. When normalizing each HKG mRNA to the other 4 HKG mRNAs, CYC increased at T3 and glyceraldehyde-3-phosphate hydrogenase decreased at T2 (p , 0.05) in younger men. This is one of the few studies to suggest that explicit HKG mRNAs should be used depending upon age group and resistance exercise intervention

Electrophoretic separation of myosin heavy chain isoforms using a modified mini gel system.

The electrophoretic separation of myosin heavy chain isoforms from muscle biopsy homogenates has been widely practiced in the field of exercise physiology to examine how intrinsic (i.e., aging) and extrinsic (i.e., training) factors affect muscle phenotype. In the past, various research groups have used large and mini polyacrylamide gel systems to perform this delicate methodology. As technology has progressed, additional gel formats have been introduced, but available methodologies appear to be lacking. In the current investigation, we successfully separated three distinct myosin heavy chain isoforms from various muscle samples using a modified mini gel system which can load up to 26 samples per gel. This paper will outline our allocated protocol as well as discuss potential troubleshooting considerations for other researchers performing this intricate methodology. The outlined methodology has resulted in an ability to clearly resolute three distinct bands at molecular weights attributed to the myosin heavy chain isoforms in human skeletal muscle at a wide range of human ages (20 - 78 y). As additional technologies become available, the need to modify and adapt existing electrophoretic protocols for myosin heavy chain isoform separation and other protocols will continue to be evident

Effect of gender on the metabolic impact of a commercially available thermogenic drink

The purpose of this study was to examine the gender effect of daily consumption of a thermogenic drink (TD) containing caffeine, epigallocatechin gallate, and taurine. In a single-blind, matched-pairs, placebo-controlled study, 60 participants (n = 30 men and n = 30 women) were matched in a balanced fashion according to age and body mass. Participants completed determination of body composition, resting energy expenditure (REE), and serum levels of glycerol and free fatty acids before and after ingesting either 336 mL of a TD or a noncaloric, noncaffeinated placebo (PLA). Participants were supplemented daily with 336 mL of either the TD or PLA and repeated identical testing procedures on day 28. Area under the curve (AUC) analysis on days 0 and 28 were calculated for all blood variables (e.g., glycerol and free fatty acids) and analyzed with REE, respiratory exchange ratio, dietary records, and body composition with separate repeated-measure analyses of variance. On days 0 and 28, REE AUC (p , 0.001) was greater in all men compared with in women. Women ingesting the TD had significantly greater free fatty acid AUC values (p = 0.002) when compared with those of men. A significant interaction for glycerol AUC (p = 0.02) revealed greater glycerol concentrations in the male PLA group, which decreased in all other groups from days 0 to 28. The male TD group lost significantly more percent body fat (p = 0.02) than did the female PLA group. The popularity of thermogenic drinks to promote weight loss and body composition changes has grown exponentially. Gender differences after drink ingestion may impact the resulting adaptations and how successful their inclusion impacts weight loss and body-composition changes in those following a regular diet and exercise program

Putting to rest the myth of creatine supplementation leading to muscle cramps and dehydration

Creatine is one of the most popular athletic supplements with sales surpassing 400 million dollars in 2004. Due to the popularity and efficacy of creatine supplementation over 200 studies have examined the effects of creatine on athletic performance. Despite the abundance of research suggesting the effectiveness and safety of creatine, a fallacy appears to exist among the general public, driven by media claims and anecdotal reports, that creatine supplementation can result in muscle cramps and dehydration. Although a number of published studies have refuted these claims, a recent position statement by the American College of Sports Medicine (ACSM) in 2000 advised individuals who are managing their weight and exercising intensely or in hot environments to avoid creatine supplementation. Recent reports now suggest that creatine may enhance performance in hot and/or humid conditions by maintaining haematocrit, aiding thermoregulation and reducing exercising heart rate and sweat rate. Creatine may also positively influence plasma volume during the onset of dehydration. Considering these new published findings, little evidence exists that creatine supplementation in the heat presents additional risk, and this should be taken into consideration as position statements and other related documents are published

Effects of pre-exercise feeding on serum hormone concentrations and biomarkers of myostatin and ubiquitin proteasome pathway activity

Purpose: The aim of the study was to examine the acute effects of pre-exercise ingestion of protein, carbohydrate, and a non-caloric placebo on serum concentrations of insulin and cortisol, and the intramuscular gene expression of myostatin- and ubiquitin proteasome pathway (UPP)- related genes following a bout of resistance exercise. Methods: Ten untrained college-aged men participated in three resistance exercise sessions (3 x 10 at 80 % 1RM for bilateral hack squat, leg press, and leg extension) in a crossover fashion, which were randomly preceded by protein, carbohydrate, or placebo ingestion 30 min prior to training. Pre-supplement/pre-exercise, 2 h and 6 h post-exercise muscle biopsies were obtained during each session and analyzed for mRNA fold changes in myostatin (MSTN), activin IIB, follistatin-like 3 (FSTL3), SMAD specific E3 ubiquitin protein ligase 1 (SMURF1), forkhead box O3, F-box protein 32 (FBXO32), and Muscle RING-finger protein-1, with beta-actin serving as the housekeeping gene. Gene expression of all genes was analyzed using real-time PCR. Results: Acute feeding appeared to have no significant effect on myostatin or UPP biomarkers. However, resistance exercise resulted in a significant downregulation of MSTN and FBXO32 mRNA expression and a significant upregulation in FSTL3 and SMURF1 mRNA expression (p<0.05). Conclusions: An acute bout of resistance exercise results in acute post-exercise alterations in intramuscular mRNA expression of myostatin and UPP markers suggestive of skeletal muscle growth. However, carbohydrate and protein feeding surrounding resistance exercise appear to have little influence on the acute expression of these markers