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

Megalin and androgen receptor gene expression in young and old human skeletal muscle before and after three sequential exercise bouts. J Strength Cond Res 25(2): 309– 317, 2011—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

Myogenic mRNA markers in young and old human skeletal muscle prior to and following sequential exercise bouts

This study examined how multiple bouts of conventional resistance training affected the mRNA expression of transcripts and a protein associated with satellite cell activity in human skeletal muscle. Ten younger men (means ± SE; age, 21.0 ± 0.5 years; body mass, 82.3 ± 4.2 kg; height, 178.4 ± 2.2 cm; percent body fat, 15.4% ± 2.9%) and 10 older men (age, 66.4 ± 1.6 years; body mass, 94.2 ± 3.7 kg; height, 180.9 ± 2.2 cm; percent body fat, 27.4% ± 1.8%) completed 3 lower-body workouts (Monday, Wednesday, Friday; 9 sets of 10 repetitions at 80% 1 repetition maximum). Vastus lateralis muscle biopsies were collected prior to intervention (T1), 48 h following workout 1 (T2), 48 h following workout 2 (T3), and 24 h following workout 3 (T4). Real-time reverse transcription-polymerase chain reaction was performed to assess genes of interest, and muscle proliferating cell nuclear antigen (PCNA) was assessed using Western blotting. The CYCLIN D1 gene was expressed more highly in the older vs. younger men (p < 0.05), whereas the expression of all other genes and muscle PCNA were similar between age groups. MYOD mRNA expression increased at T2 (p < 0.05) and MHCEMB gene expression modestly increased (p < 0.05) at T4 relative to baseline expression values in the younger men. Baseline elevations in CYCLIN D1 mRNA expression in older persons may indicate that a compensatory expression of this transcript is occurring in an attempt to retain the muscle's proliferative potential. Increases in MYOD and MHCEMB indicate that 1 week of conventional resistance exercise may i crease myogenic activity, including satellite cell proliferation and differentiation, respectively, in younger men

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

Poole, CN, Roberts, MD, Dalbo, VJ, Tucker, PS, Sunderland, KL, DeBolt, ND, Billbe, BW, and Kerksick, CM. 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. J Strength Cond Res 25(1): 51–60, 2011—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, _ VO2max, 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; 2165 years, 168 68 cm, 75.4612.7 kg, 31.6 67.7¿AT) or placebo (PLA: 6 men, 6 women; 22 6 4 years, 174 6 9 cm, 84.1 6 8.8 kg, 30.2 6 5.6¿AT) group. Both groups performed 3 d_wk21 of combined progressive RT (2 3 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 3 T; p = 0.048) improved in WLS and systolic blood pressure (SBP) approached significance (G 3 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

Acute loading and aging effects on myostatin pathway biomarkers in human skeletal muscle after three sequential bouts of resistance exercise

To determine the influence of age and resistance exercise on myostatin pathway-related genes, younger (n = 10; 28 ± 5 years) and older (n = 10; 68 ± 6 years) men underwent four testing conditions (T1-T4). A baseline (T1) muscle sample was obtained, whereas the second and third biopsies were obtained 48 hours following the first and second training sessions (T2, T3), and a final biopsy was taken 24 hours following T3. The training sessions consisted of 3 sets of 10 repetitions (80% of one repetition maximum) on leg press, hack squat, and leg extension exercises. Follistatin (FST) messenger RNA was greater in older compared with younger men at T1 and T2 (p < .05). Follistatin-like 3 (FSTL3) messenger RNA was greater in older compared with younger men at T1 and T4 (p < .05). In older men, there was a significant decrease in myostatin (MSTN) messenger RNA at T4 (p < .05). Older men contained less active (Ser-425 phosphorylated) SMAD3 (p-SMAD3) protein than younger men at T3 and T4 (p < .05). Although it is well known that younger individuals possess a greater hypertrophic potential to resistance exercise, it appears that older individuals may paradoxically possess a more favorable resistance exercise response regarding myostatin pathway-related genes and a protein marker of pathway activity. Future research is warranted to examine the physiological significance of this age-dependent mechanism

Effect of caffeine on golf performance and fatigue during a competitive tournament

Purpose: This study aimed to determine the effect of a caffeine-containing supplement on golf-specific performance and fatigue during a 36-hole competitive golf tournament. Methods: Twelve male golfers (34.8 ± 13.9 yr, 175.9 ± 9.3 cm, 81.23 ± 13.14 kg) with a United States Golf Association handicap of 3–10 participated in a double-blind, placebo-controlled, crossover design in which they played an 18-hole round of golf on two consecutive days (36-hole tournament) and were randomly assigned to consume a caffeine-containing supplement (CAF) or placebo (PLA). CAF/PLA was consumed before and after nine holes during each 18-hole round. Total score, drive distance, fairways and greens in regulation, first putt distance, HR, breathing rate, peak trunk acceleration, and trunk posture while putting were recorded. Self-perceived ratings of energy, fatigue, alertness and concentration were also recorded.Results: Total score (76.9 ± 8.1 vs 79.4 ± 9.1, P = 0.039), greens in regulation (8.6 ± 3.3 vs 6.9 ± 4.6, P = 0.035), and drive distance (239.9 ± 33.8 vs 233.2 ± 32.4, P = 0.047) were statistically better during the CAF condition compared with those during PLA. Statistically significant main effects for condition (P 0.05).Conclusions: A moderate dose (1.9 ± 0.3 mg·kg−1) of caffeine consumed before and during a round of golf improves golf-specific measures of performance and reduces fatigue in skilled golfers

IGF-1 splice variant and IGF-1 peptide expression patterns in young and old human skeletal muscle prior to and following sequential exercise bouts

Genes and proteins involved in insulin-like growth factor (IGF)-1 signaling are thought to be differentially expressed in older versus younger mammalian skeletal muscle following acute exercise. The purpose of this study was to examine how multiple bouts of conventional resistance training meant to elicit hypertrophy affect the mRNA expression of IGF-1EA and IGF-1EC (MGF) as well as the expression of total IGF-1 peptides in human skeletal muscle. Ten younger (18–25 years) and 10 older (60–75 years) males completed three sequential workouts (M, W, F) consisting of nine sets of lower body exercises with ten repetitions per set at an intensity of 80% of one repetition maximum. Vastus lateralis muscle biopsies were collected prior to intervention (T1), 48 h following workout 1 (T2), 48 h following workout 2 (T3), and 24 h following workout 3 (T4). RT-PCR was performed to assess baseline and changes in MGF and IGF-IEA mRNA. Samples were also assayed for total muscle IGF-1 peptides using ELISA-based methods. There were no baseline differences in MGF or IGF-1EA mRNA expression and IGF-1 peptides between age groups. Interestingly, MGF expression increased at T2–T4 in the older group relative to baseline values (p < 0.05), albeit muscle IGF-1EA mRNA

Effect of caffeine on golf performance and fatigue during a competitive tournament

Purpose: This study aimed to determine the effect of a caffeine-containing supplement on golf-specific performance and fatigue during a 36-hole competitive golf tournament. Methods: Twelve male golfers (34.8 ± 13.9 yr, 175.9 ± 9.3 cm, 81.23 ± 13.14 kg) with a United States Golf Association handicap of 3–10 participated in a double-blind, placebo-controlled, crossover design in which they played an 18-hole round of golf on two consecutive days (36-hole tournament) and were randomly assigned to consume a caffeine-containing supplement (CAF) or placebo (PLA). CAF/PLA was consumed before and after nine holes during each 18-hole round. Total score, drive distance, fairways and greens in regulation, first putt distance, HR, breathing rate, peak trunk acceleration, and trunk posture while putting were recorded. Self-perceived ratings of energy, fatigue, alertness and concentration were also recorded.Results: Total score (76.9 ± 8.1 vs 79.4 ± 9.1, P = 0.039), greens in regulation (8.6 ± 3.3 vs 6.9 ± 4.6, P = 0.035), and drive distance (239.9 ± 33.8 vs 233.2 ± 32.4, P = 0.047) were statistically better during the CAF condition compared with those during PLA. Statistically significant main effects for condition (P 0.05).Conclusions: A moderate dose (1.9 ± 0.3 mg·kg−1) of caffeine consumed before and during a round of golf improves golf-specific measures of performance and reduces fatigue in skilled golfers