Intramuscular adaptations to eccentric exercise and antioxidant supplementation

Prophylactic supplementation of N-acetyl-cysteine (NAC) and epigallocatechin gallate (EGCG) was studied for physiological and cellular changes in skeletal muscle after eccentric muscle contractions. Thirty healthy, active males (20.0 ± 1.8 years, 160 ± 7.1 cm, 76.1 ± 17.0 kg) ingested for 14 days either 1,800 mg of NAC, 1,800 mg of EGCG, or 1,000 mg of fiber (glucomannan) placebo (PLC) in a double blind, prophylactic fashion. Subjects completed one eccentric exercise bout (100 repetitions at 30°/s) using the dominant knee extensors. Strength and soreness were assessed, and blood and muscle samples obtained before and 6, 24, 48, and 72 h with no muscle sample being collected at 72 h. Separate mixed factorial repeated measures ANOVA (P < 0.05) were used for all statistical analysis. All groups experienced significantly reduced peak torque production after 6 and 24 h, increased soreness at all time points from baseline [with even greater soreness levels 24 h after exercise in PLC when compared to EGCG and NAC (P < 0.05)], increased lactate dehydrogenase at 6 h, and increased creatine kinase 6, 24 and 48 h after exercise. No significant group × time interaction effects were found for serum cortisol, neutrophil counts, and the neutrophil:lymphocyte ratio; although, all values experienced significant changes 6 h after exercise (P < 0.05), but at no other time points. At 48 h after the exercise bout the Neu:Lym ratio in EGCG was significantly less than NAC (P < 0.05), whereas there was a trend (P = 0.08) for the EGCG values to be less when compared to PLC at this time point. Markers of intramuscular mitochondrial and cytosolic apoptosis were assessed (e.g., bax, bcl-2, cytochrome C, caspase-3 content/enzyme activity, and total DNA content). Significant increases (P < 0.05) in muscle levels of bax and bcl-2 were observed in all groups with no significant differences between groups, whereas no changes (P > 0.05) were reported for cytochrome C, caspase-3 content, caspase-3 enzyme activity, and total DNA. Caspase-3 enzyme activity was significantly greater in all groups 48 h after exercise when compared to baseline (P < 0.05) and 6 h (P < 0.05) after exercise. An eccentric bout of muscle contractions appears to significantly increase muscle damage, markers of mitochondrial apoptosis, apoptotic enzyme activity, and whole-blood cell markers of inflammation with no changes in oxidative stress. While soreness ratings were blunted in the two supplementation groups 24 h after exercise when compared to PLC values, more research is needed to determine the potential impact of EGCG and NAC supplementation on changes related to oxidative stress, apoptosis, and eccentric exercise.     

Sports performance graduate program interest and need survey: a brief report from the NSCA Education Committee

The Education Recognition Program (ERP) was developed to acknowledge academic institutions meeting departmental criteria established by the National Strength and Conditioning Association (NSCA) for having an area of concentration in undergraduate strength and conditioning. Since its inception, over 40 universities have received recognition status. The NSCA is currently examining the interest, need, and feasibility of creating an ERP for graduate curriculum specific to sports performance. The current investigation included a survey of Division I, II, and III strength and conditioning professionals. Surveys were mailed to 215 coaches, of which 53 responded (26% rate of return). Five factors were extracted from the questionnaire and were subsequently named: Application of Science to Strength and Conditioning, Professional Development, Graduate Curriculum Support, Graduate Program Requirements, and Graduate Assistantships. A one-way analysis of variance (ANOVA) found significant differences on Application of Science to Strength and Conditioning and Professional Development when comparing highest degree earned. Pairwise analysis indicated that individuals with Master's degrees scored those factors higher compared with individuals with Bachelor's degrees. The results from this survey provide initial information from current strength and conditioning professionals regarding the interest and need for developing formalized graduate curriculum specifically for sports performance.     

Low vs. high glycemic index carbohydrate gel ingestion during simulated 64-km cycling time trial performance

We examined the effect of low and high glycemic index (GI) carbohydrate (CHO) feedings during a simulated 64-km cycling time trial (TT) in nine subjects ([mean +/- SEM], age = 30 +/- 1 years; weight = 77.0 +/- 2.6 kg). Each rider completed three randomized, double blind, counter-balanced, crossover rides, where riders ingested 15 g of low GI (honey; GI = 35) and high GI (dextrose; GI = 100) CHO every 16 km. Our results showed no differences between groups for the time to complete the entire TT (honey = 128 minutes, 42 seconds +/- 3.6 minutes; dextrose = 128 minutes, 18 seconds +/- 3.8 minutes; placebo = 131 minutes, 18 seconds +/- 3.9 minutes). However, an analysis of total time alone may not portray an accurate picture of TT performance under CHO-supplemented conditions. For example, when the CHO data were collapsed, the CHO condition (128 minutes, 30 seconds) proved faster than placebo condition (131 minutes, 18 seconds; p < 0.02). Furthermore, examining the percent differences and 95% confidence intervals (CI) shows the two CHO conditions to be generally faster, as the majority of the CI lies in the positive range: placebo vs. dextrose (2.36% [95% CI; -0.69, 4.64]) and honey (1.98% [95% CI; -0.30, 5.02]). Dextrose vs. honey was 0.39% (95% CI; -3.39, 4.15). Within treatment analysis also showed that subjects generated more watts (W) over the last 16 km vs. preceding segments for dextrose (p < 0.002) and honey (p < 0.0004) treatments. When the final 16-km W was expressed as a percentage of pretest maximal W, the dextrose treatment was greater than placebo (p < 0.05). A strong trend was noted for the honey condition (p < 0.06), despite no differences in heart rate (HR) or rate of perceived exertion (RPE). Our results show a trend for improvement in time and wattage over the last 16 km of a 64-km simulated TT regardless of glycemic index.     

Megalin and androgen receptor gene expression in young and old human skeletal muscle before and after three sequential exercise bouts

Androgen signaling occurs primarily via the androgen receptor. Megalin, a low-density lipoprotein endocytic receptor located in various mammalian tissues, has been recently shown to facilitate sex hormone–binding globulin (SHBG) steroid complexes across cell membranes. The purpose of this investigation is to determine if the megalin gene is expressed in human skeletal muscle and if present to determine how megalin and androgen receptor mRNA expression change in response to sequential exercise bouts with respect to aging. Ten younger (age: 18-25 years) and 10 older (age: 60-75 years) men completed 3 workouts (M, W, F) each consisting of 9 sets of lower-body exercises with 10 repetitions per set at 80% 1 repetition maximum. Vastus lateralis muscle biopsies were extracted at baseline (T1), 48 hours after workout 1 (T2) and 2 (T3), and 24 hours after workout 3 (T4), and blood samples were collected before and 5 minutes after each workout. Muscle was analyzed for megalin and androgen receptor expression using gene-specific primers and SYBR green chemistry, and blood was analyzed for serum testosterone, SHBG, and the free androgen index. Megalin was expressed in both young and old subjects across all time points, although no between- or within-group mean differences were detected at any time point. Androgen receptor was expressed higher in young men at all time points compared to in old men (p < 0.05), and a significant correlation (p < 0.05; r = 0.506) was found between serum testosterone and androgen receptor after workout 1. Based on our data, the gene coding for megalin is expressed inside skeletal muscle, but its role, if any, in steroid cellular transport cannot be determined. This finding could lay the groundwork for more mechanistic investigations to better delineate its functional role and its potential as a therapeutic adjunct for androgen-related disorders in healthy and aged populations.     

Genome‐wide DNA methylation changes with age in disease‐free human skeletal muscle

A decline in skeletal muscle mass and function with aging is well recognized, but remains poorly characterized at the molecular level. Here, we report for the first time a genome‐wide study of DNA methylation dynamics in skeletal muscle of healthy male individuals during normal human aging. We predominantly observed hypermethylation throughout the genome within the aged group as compared to the young subjects. Differentially methylated CpG (dmCpG) nucleotides tend to arise intragenically and are underrepresented in promoters and are overrepresented in the middle and 3′ end of genes. The intragenic methylation changes are overrepresented in genes that guide the formation of the junction of the motor neuron and myofibers. We report a low level of correlation of gene expression from previous studies of aged muscle with our current analysis of DNA methylation status. For those genes that had both changes in methylation and gene expression with age, we observed a reverse correlation, with the exception of intragenic hypermethylated genes that were correlated with an increased gene expression. We suggest that a minimal number of dmCpG sites or select sites are required to be altered in order to correlate with gene expression changes. Finally, we identified 500 dmCpG sites that perform well in discriminating young from old samples. Our findings highlight epigenetic links between aging postmitotic skeletal muscle and DNA methylation.     

The combined effects of exercise and ingestion of a meal replacement in conjunction with a weight loss supplement on body composition and fitness parameters in college-aged men and women

This study was performed to evaluate the combined effect of a meal replacement and an alleged weight loss supplement (WLS) on body composition, fitness parameters, and clinical health in moderately overweight college-aged men and women. Body mass, bench press 1 repetition maximum (1RM), leg press 1RM, body composition, V(O2)max, fasting glucose (GLU), and lipid panels were evaluated before (T1) and after (T2) 8 weeks of combined resistance training (RT) and cardiovascular training (CVT). After T1, subjects were randomly assigned in a double-blind fashion to either the WLS (6 men, 7 women; 21 ± 5 years, 168 ± 8 cm, 75.4 ± 12.7 kg, 31.6 ± 7.7%BFAT) or placebo (PLA: 6 men, 6 women; 22 ± 4 years, 174 ± 9 cm, 84.1 ± 8.8 kg, 30.2 ± 5.6%BFAT) group. Both groups performed 3 d · wk(-1) of combined progressive RT (2 × 12 reps of 8 exercises at 75-80% 1RM) and CVT (30 minutes on a cycle ergometer at 70-85% heart rate reserve). Subjects consumed 4 capsules per day and a once-daily meal replacement throughout the protocol. Percent body fat, bench press 1RM, and leg press 1RM significantly improved (p < 0.05) in both groups. Blood GLU (G × T; p = 0.048) improved in WLS and systolic blood pressure (SBP) approached significance (G × T; p = 0.06) in the WLS group. Follow-up analysis of SBP revealed a significant within-group decrease in the WLS group, whereas no within-group changes were found for either group for GLU. Practically speaking, daily supplementation with a meal replacement and a thrice weekly exercise program can increase fitness levels and improve body composition, whereas adding a thermogenic substance provides no additional benefit over fitness or body composition changes but may favorably alter serum markers of clinical health.     

The effects of protein and amino acid supplementation on performance and training adaptations during ten weeks of resistance training

The purpose of this study was to examine the effects of whey protein supplementation on body composition, muscular strength, muscular endurance, and anaerobic capacity during 10 weeks of resistance training. Thirty-six resistance-trained males (31.0 +/- 8.0 years, 179.1 +/- 8.0 cm, 84.0 +/- 12.9 kg, 17.8 +/- 6.6%) followed a 4 days-per-week split body part resistance training program for 10 weeks. Three groups of supplements were randomly assigned, prior to the beginning of the exercise program, in a double-blind manner to all subjects: 48 g per day (g.d(-1)) carbohydrate placebo (P), 40 g.d(-1) of whey protein + 8 g.d(-1) of casein (WC), or 40 g.d(-1) of whey protein + 3 g.d(-1) branched-chain amino acids + 5 g.d(-1) L-glutamine (WBG). At 0, 5, and 10 weeks, subjects were tested for fasting blood samples, body mass, body composition using dual-energy x-ray absorptiometry (DEXA), 1 repetition maximum (1RM) bench and leg press, 80% 1RM maximal repetitions to fatigue for bench press and leg press, and 30-second Wingate anaerobic capacity tests. No changes (p > 0.05) were noted in all groups for energy intake, training volume, blood parameters, and anaerobic capacity. WC experienced the greatest increases in DEXA lean mass (P = 0.0 +/- 0.9; WC = 1.9 +/- 0.6; WBG = -0.1 +/- 0.3 kg, p < 0.05) and DEXA fat-free mass (P = 0.1 +/- 1.0; WC = 1.8 +/- 0.6; WBG = -0.1 +/- 0.2 kg, p < 0.05). Significant increases in 1RM bench press and leg press were observed in all groups after 10 weeks. In this study, the combination of whey and casein protein promoted the greatest increases in fat-free mass after 10 weeks of heavy resistance training. Athletes, coaches, and nutritionists can use these findings to increase fat-free mass and to improve body composition during resistance training.     

The effects of age on skeletal muscle and the phosphocreatine energy system: can creatine supplementation help older adults

Creatine supplementation has been found to significantly increase muscle strength and hypertrophy in young adults (≤ 35 yr) particularly when consumed in conjunction with a resistance training regime. Literature examining the efficacy of creatine supplementation in older adults (55-82 yr) suggests creatine to promote muscle strength and hypertrophy to a greater extent than resistance training alone. The following is a review of literature reporting on the effects of creatine supplementation on intramuscular high energy phosphates, skeletal muscle morphology and quality of life in older adults. Results suggest creatine supplementation to be a safe, inexpensive and effective nutritional intervention, particularly when consumed in conjunction with a resistance training regime, for slowing the rate of muscle wasting that is associated with aging. Physicians should strongly consider advising older adults to supplement with creatine and to begin a resistance training regime in an effort to enhance skeletal muscle strength and hypertrophy, resulting in enhanced quality of life.