This study examined whether supplementing the diet with a commercial supplement containing zinc magnesium aspartate (ZMA) during training affects zinc and magnesium status, anabolic and catabolic hormone profiles, and/or training adaptations. Forty-two resistance trained males (27 +/- 9 yrs; 178 +/- 8 cm, 85 +/- 15 kg, 18.6 +/- 6% body fat) were matched according to fat free mass and randomly assigned to ingest in a double blind manner either a dextrose placebo (P) or ZMA 30-60 minutes prior to going to sleep during 8-weeks of standardized resistance-training. Subjects completed testing sessions at 0, 4, and 8 weeks that included body composition assessment as determined by dual energy X-ray absorptiometry, 1-RM and muscular endurance tests on the bench and leg press, a Wingate anaerobic power test, and blood analysis to assess anabolic/catabolic status as well as markers of health. Data were analyzed using repeated measures ANOVA. Results indicated that ZMA supplementation non-significantly increased serum zinc levels by 11 - 17% (p = 0.12). However, no significant differences were observed between groups in anabolic or catabolic hormone status, body composition, 1-RM bench press and leg press, upper or lower body muscular endurance, or cycling anaerobic capacity. Results indicate that ZMA supplementation during training does not appear to enhance training adaptations in resistance trained populations.
Twenty‐four participants (15 men; 9 women) performed baseline testing (day 1) after following a standard unsupplemented diet. This was followed by the daily ingestion of a creatine formulation dietary loading sequence for 5 days (days 2–6, Phosphagen HP™ 5.25 g creatine mono‐hydrate (CR) 4‐ 33 g dextrose). Loading consisted of 4 servings of Phosphagen HP™ per day. On day 7, participants were randomly assigned to one of three double‐blind treatments administered 1 h before testing. During treatment, subjects were randomly fed: (a) 10 g of CR, (b) 80 g of dextrose, or (c) 10 g of CR + 80 g of dextrose. Variables evaluating the effectiveness of the different regimens included body mass, two 30‐s Wingate anaerobic performance power tests and measurement of serum creatine concentration 65 and 5 min before each trial. Plasma ammonia concentration was also measured 65 min before and 5 min after each trial. The results of this trial show a significant non‐placebo controlled effect for the pooled, group and gender data (P ≤ 0.05). Following 5 days of Phosphagen HP™ loading, significant pooled group mean changes were: (1) body mass (+1.08 kg), (2) anaerobic power (1st Wingate = + 1.28 kJ; 2nd Wingate 2 = (+1.92kJ), (3) serum creatine concentration 65 min prior to testing trials (+624.06 μmol · L−1) and (4) post‐test plasma ammonia concentration (—83.63 μmol · L−1). However, on day 7, in placebo group condition, no between group performance effects were noted following an acute 10 g oral bolus of CR 1 h prior to the exercise test. It is concluded that no performance benefit is due to acute ingestion of CR 1 h before exercise in CR loaded individuals.
Dual Energy X-ray Absorptiometry (DEXA) has gained popularity as a valid measure of human body composition. A distinct advantage of this method is its ability to partition/section the body into regions for analysis. While much information has been reported in regards to body composition changes in overweight or sedentary populations, little information has been reported concerning the regional fat and lean composition of the human body of active males across the age span. PURPOSE: To assess the absolute and relative amounts of bone, fat and lean tissue in men across three age groups. METHODS: Moderately active and apparently healthy men (26.9±8.2y, 178.1±7.31cm, 84.2±14.5kg, 17.3±6.6% fat, n=334) had whole-body body composition scans completed using a Hologic QDR-4500W DEXA (version 9.80C). Participants were required to have been weight training on their entire body for a minimum of 6 months at least 3 days per week. All subjects were divided into three age cohorts (Y1: <25y, Y2:26–35y, and O:36–50y) and reported as M±SD, respectively. RESULTS: Multivariate ANO VA revealed no significant difference in height among all three groups and no difference in weight for Y1 (80.7±12.7kg) and Y2 (86.9±14.6kg). No differences in total bone mineral density were found for any age group. The O group had significantly greater body mass (p < 0.05) as well as absolute fat content on the upper body (right arm + left arm + trunk fat) (Y1:7.3±3.9, O:12.3±6.9kg, p < 0.05) and both legs (Y1:4.9±2.6, O:5.9±2.6 kg, p < 0.05) compared to Y1. Groups Y1 and Y2 were not significantly different in fat content of the legs but Y2 had significantly more trunk fat than Y1 (Y1: 6.1±7.5kg and Y2:9.1±13.7kg, p < .0.05). All groups were similar in lean tissue mass of the extremities, but Y1 had significantly less trunk lean tissue mass than the other two groups (Y1:30. 2±5.5, Y2:31.9±7.9, O:32.9±9.4 kg, p < 0.05). Comparing these tissues produced higher fat-to-lean ratios for the older group for the arms and trunk not for legs. CONCLUSIONS: The greater fat content of older men appears to be due to accumulation on the arms and trunk but not on the legs. It appears that pronounced changes in body composition distribution occur during 26–35 years of age in recreationally resistance-trained males. The pattern of adipose and lean tissue distribution throughout the age span appears to occur irrespective of their resistance training background in comparison to previous findings.
Earnest, C.P., S. Lancaster, C. Rasmussen, C. Kerksick, A. Lucia, M. Greenwood, A. Almada, P. Cowan, and R. Kreider. Low vs. high glycemic index carbohydrate gel ingestion during simulated 64-km cycling time trial performance. J. Strength Cond. Res. 18(3):466–472. 2004.—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, counterbalanced, 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.
We recently reported that ingesting a supplement containing creatine, yeast-derived RNA, taurine & glutamine significantly increased lean tissue mass in resistance-trained males (MSSE 27:S169, 1995). This study examined whether ingesting similar supplements during 35 days of off-season resistance/agility training (8 hr/wk) would effect absolute and/or lean tissue mass adjusted isokinetic strength performance. In a double-blind and randomized manner, 43 NCAA division 1A football players were matched to body weight and assigned to supplement their diet with either: 195 g/d of maltodextrin (M); Phosphagain™ containing 64 g/d carbohydrate, 67 g/d protein, 5 g/d fat, 20 g/d of creatine monohydrate, 0.775 g/d of yeast-derived RNA, 7.2 g/d of L-glutamine, & 6.2 g/d of taurine (P); or, Phosphagain II™ containing 45 g/d carbohydrate, 72 g/d protein, 6 g/d fat, 25.5 g/d of creatine monohydrate, 1.5 g/d of yeast-derived RNA, 9 g/d of L-glutamine, 10.5 g/d of taurine & 6.75 g/d of calcium α-ketoglutarate (P-II). On days 0 and 35 of supplementation, body composition was determined using dual energy x-ray absorptiometry (DXA) and subjects performed three 1 RM concentric-only isokinetic bench press tests at ascending bar velocities of 0.25, 0.99, and 1.74 m·s-1 on the Ariel 5000 computerized ergometer. Subjects also performed 5 sets of 15 maximal-effort repetitions at an ascending bar velocity of 0.25 m·s-1 with 60-s of rest between sets. Absolute and lean tissue mass normalized isokinetic data were analyzed by ANOVA with repeated measures. Results revealed that gains in lean tissue mass were significantly greater in the P and P-II groups (M 1,038±475; P 2,433±346; P-II 3,450±526 g) and that gains in absolute total work values tended to be greater (p=0.053) at the 0.99 m·s-1 velocity in the P and P-II groups. However, no significant differences were observed among groups in remaining 1 RM velocities or in absolute or relative set to set and overall peak force, average force, and work values during the 5 sets of 15 maximal-effort concentric-only contractions. Results indicate that despite significant gains in lean tissue mass, P and P-II supplementation have limited effects on multijoint isokinetic performance in comparison to a maltodextrin placebo.
Creatine is one of the most popular nutritional ergogenic aids for athletes. Studies have consistently shown that creatine supplementation increases intramuscular creatine concentrations which may help explain the observed improvements in high intensity exercise performance leading to greater training adaptations. In addition to athletic and exercise improvement, research has shown that creatine supplementation may enhance post-exercise recovery, injury prevention, thermoregulation, rehabilitation, and concussion and/or spinal cord neuroprotection. Additionally, a number of clinical applications of creatine supplementation have been studied involving neurodegenerative diseases (e.g., muscular dystrophy, Parkinson’s, Huntington’s disease), diabetes, osteoarthritis, fibromyalgia, aging, brain and heart ischemia, adolescent depression, and pregnancy. These studies provide a large body of evidence that creatine can not only improve exercise performance, but can play a role in preventing and/or reducing the severity of injury, enhancing rehabilitation from injuries, and helping athletes tolerate heavy training loads. Additionally, researchers have identified a number of potentially beneficial clinical uses of creatine supplementation. These studies show that short and long-term supplementation (up to 30 g/day for 5 years) is safe and well-tolerated in healthy individuals and in a number of patient populations ranging from infants to the elderly. Moreover, significant health benefits may be provided by ensuring habitual low dietary creatine ingestion (e.g., 3 g/day) throughout the lifespan. The purpose of this review is to provide an update to the current literature regarding the role and safety of creatine supplementation in exercise, sport, and medicine and to update the position stand of International Society of Sports Nutrition (ISSN).
This study examined whether ribose supplementation before and during intense anaerobic exercise impacts anaerobic capacity and metabolic markers. Twelve moderately trained male cyclists (22.3 +/- 2.2 y; 181 +/- 6 cm, 74.8 +/- 9 kg) participated in the study. Subjects were familiarized and fasted for 8 h after standardizing nutritional intake. In a double blind and crossover manner subjects ingested either a 150 mL placebo or ribose (3 g ribose + 150 microg folate). Subjects rested for 25 min and completed 5 x 30 s anaerobic capacity tests with 3 min passive rest. Six capillary blood samples were taken prior to and after sprints for adenine nucleotide breakdown determination. The experiment was repeated 1 wk later with alternative drink. Data were analyzed by repeated measures ANOVA. No significant interactions were observed for any performance or blood variables. D-ribose supplementation has no impact on anaerobic exercise capacity and metabolic markers after high-intensity cycling exercise.
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