The effects of supplementation with creatine and protein on muscle strength following a traditional resistance training program in middle-aged and older men.

OBJECTIVES: Creatine and protein supplementation can enhance the training outcomes of young subjects, but it is not clear if there are benefits for older individuals. Therefore, the purpose of this study was to determine the effects of creatine and protein supplementation on strength gains following a traditional resistance training program for middle-aged and older men. DESIGN, SETTING, PARTICIPANTS: This study assessed changes in strength of men aged 48-72 years following 14 weeks of resistance training supplemented with creatine and/or protein. A double-blind, randomized, placebo-controlled design placed 42 males into one of four groups: Resistance Trained Placebo (RTP, n=10); Resistance Trained Creatine (RTCr, 5g Cr, n=10); Resistance Trained Protein (RTPr, 35g whey Pr, n=11); or Resistance Trained Creatine and Protein (RTCrPr, 5g Cr and 35g Pr, n=11). INTERVENTION: All groups trained 3 days per week for 14 weeks. The resistance training program was based on progressive overload. Training loads corresponded to 80% 1 RM (one repetition maximum strength), 3 sets of 8 repetitions for the following exercises: knee extension/knee flexion; bicep curl/tricep extension; military press; lat pull down; seated leg press; and bench press. MEASUREMENTS: 1 RM for each exercise and measures of lean body mass were assessed prior to and following the 14 week program. RESULTS: Each group significantly (p < 0.05) increased strength and lean body mass, however, there were no significant group effects or group X trial interactions. CONCLUSION: Resistance training in middle-aged and older men significantly increased muscular strength and added muscle mass with no additional benefits from creatine and/or protein supplementation.

The effects of creatine and whey protein supplementation on body composition in men aged 48 to 72 years during resistance training.

OBJECTIVES: Creatine and whey protein are supplements believed to have an ergogenic effect. Very little is known regarding the effects of these dietary supplements in older men. The purpose of this study was to determine the effect of creatine and whey protein supplements, consumed independently and in combination, on total and regional body composition in middle-aged men during a resistance-training program. DESIGN, SETTING, PARTICIPANTS: Forty-two men were randomly assigned to four groups to receive supplements according to a double-blind protocol. Groups consumed their supplements three times per week immediately following their resistance training sessions. The groups were: 1) placebo (480 ml of Gatorade); 2) creatine (480 ml of Gatorade plus 5 grams of creatine); 3) whey protein (480 ml of Gatorade plus 35 grams of whey protein powder); and 4) whey protein/creatine (480 ml of Gatorade plus 5 grams of creatine and 35 grams of whey protein powder). All groups participated in resistance training 3 times per week for 14 weeks. MEASUREMENTS: At the beginning and end of the study, total and regional measures of body composition (DXA) and total (TBW), intracellular (ICW), and extracellular (ECW) body water (Multifrequency BIA) were measured and 3-day diet records were completed. RESULTS: There were significant training effects for regional arm fat (decrease), regional arm bone free-fat free mass (BF-FFM - increase), total body BF-FFM (increase), ICW (increase), and ECW (increase) but no significant group effects and only one significant group by training interaction (ECW). There were no significant changes for total calorie, carbohydrate, fat or protein intake for any of the groups from prestudy to post-study testing. CONCLUSION: The results from this study suggest that supplementation with creatine, whey protein, or a combination of creatine and whey protein, when combined with resistance training in middle-aged men, have no added benefit to changes that occur to body composition due to resistance training alone.

Effects of creatine supplementation on isometric force-time curve characteristics.

PURPOSE: To assess the effects of creatine monohydrate on isometric force-time curve parameters of sedentary college males aged 18-25 yr. METHODS: This double-blind study randomly assigned subjects to either a treatment (with creatine (Cr)) group (N = 11) or placebo group (P) (N = 8). The Cr group received 20 g x d(-1) of Cr for the first 5 d, in 5-g doses, four times daily (loading period) followed by a 5-g x d(-1) dose for the next 5 d (maintenance phase) and then no Cr ingestion for 7 d (washout period). Each 5-g dose was mixed with 250 mL of Gatorade. The P group received a placebo (cornstarch) following the exact same dosage regimen and protocol as the Cr group. All subjects were sedentary and had not used any nutritional supplements for 6 months before the study. Measurements of isometric force production of four muscle groups (elbow flexors and extensors; knee flexors and extensors) were characterized by a number of force-time parameters including strength (MF), time to maximal force (TMF), rate of force development (MRFD), and intermittent endurance (total impulse (TI) and percent force decrement (PFD)). Testing was done at pretreatment, after the 10-d loading and maintenance phases, and after the washout phase. RESULTS: Repeated measures ANOVA indicated no significant group effect for any muscle group concerning the maximal strength parameters and only two significant time effects for the knee flexors during MF and MRFD. Similarly, there were no significant group effects for any muscle group during the endurance trials; however, there was a significant time effect concerning TI for each muscle group tested. CONCLUSION: Our findings indicate that oral supplementation with creatine monohydrate in untrained males does not positively influence isometric strength but may enhance intermittent isometric muscular endurance.

Creatine supplementation during resistance training in college football athletes.

PURPOSE: This investigation assessed the effects of a 9-wk regimen of creatine monohydrate (Cr x H2O) supplementation coupled with resistance training on body composition and neuromuscular performance in NCAA Division I football athletes. METHODS: Twenty-five subjects were randomly assigned in a double-blind, randomized placebo-controlled design, to a treatment (Cr, N = 9), placebo (P, N = 8), or control group (C, N = 8). The Cr group received 20 g.d(-1) of creatine for the first 5 d in 5-g doses, four times daily, followed by 5 g.d(-1) for the remainder of the study. Each 5-g dose was mixed with 500 mL of glucose solution (Gatorade). The P group received a placebo (sodium phosphate monohydrate; NaH2PO4 x H2O) following the exact protocol as the Cr group. The C group received no supplementation. All subjects resistance trained 4 d.wk(-1). Measurements of neuromuscular performance and body composition were made pre- and post-training after supplementation while monitoring dietary intakes. RESULTS: Repeated measures ANOVA indicated significant differences occurred between the Cr group and the other two groups (P and C) for total body weight, lean body mass, cell hydration, strength, peak torque at 300 degrees.s(-1) knee flexion, percent torque decrement, and anaerobic power and capacity. However, percent body fat, peak torque during both knee flexion and extension at 60 and 180 degrees.s(-1), peak torque at 300 degrees.s(-1) during knee extension, global muscular strength (power clean), and extracellular fluid remained statistically unchanged for all groups. CONCLUSIONS: Our findings indicate that creatine, supplemented concurrently with resistance and anaerobic training, may positively affect cell hydration status and enhance performance variables further than augmentation seen with training alone.

Chromium picolinate effects on body composition and muscular performance in wrestlers.

PURPOSE: The purpose of this study was to assess the effects of 14 wk of chromium picolinate supplementation during the final 16 wk of a preseason resistance and conditioning program on body composition and neuromuscular performance in NCAA Division I wrestlers. During this phase of training, wrestlers are primarily interested in trying to improve physical performance and wrestling technique and are not engaged in severe, acute weight loss practices commonly employed before competition. METHODS: This double-blinded, randomized placebo-controlled study involved 20 wrestlers from the University of Oklahoma assigned to either a treatment group (Cr+3; N = 7; 20.4 yr +/- 0.1) receiving 200 micrograms chromium picolinate daily, a placebo group (P; N = 7; 19.9 yr +/- 0.2), or a control group (C; N = 6; 20.2 yr +/- 0.1) using a stratified random sampling technique based on weight classification. Body composition, neuromuscular performance, metabolic performance, and serum insulin and glucose were measured before and immediately following the supplementation and training period. RESULTS: Repeated measures ANOVA indicated no significant changes in body composition for any of the groups. Aerobic power increased significantly (P < 0.002) in all groups, independent of supplementation. There were significant trial and group x trial interactions for upper body endurance (P = 0.038) and relative bench press power (P = 0.050). Post-hoc analyses revealed that the C group increased upper body endurance (P = 0.006), but none of the pre- to post-test changes in bench press power were significant. CONCLUSIONS: These results suggest that chromium picolinate supplementation coupled with a typical preseason training program does not enhance body composition or performance variables beyond improvements seen with training alone.

Changes in the plantaris muscle as an indicator of alterations in lean body mass of obese Zucker rats following prolonged energy restriction and subsequent partial recovery.

To study the effects of a prolonged (80 day), severe (64% body mass loss) energy restriction and subsequent refeeding on skeletal muscle tissue, specifically the plantaris muscle, 21 genetically obese Zucker rats were selected for this study. Six rats were initially killed and served as baseline (BASE), then 15 rats underwent severe energy restriction for 80 days. Seven of these restricted rats (RESTRICT) were then killed and assessed while the other eight rats (REHAB) were fed a dry rehabilitation diet that provided 100% of the recommended energy and 1.5 times the recommended protein for growth. Once the REHAB rats had recovered approximately 45% of their original mass loss, these animals were then evaluated. Within 20 min after being killed, the plantaris muscles from each animal in each group had been removed, weighed, and frozen. Analyses included total plantaris mass, as well as differences in fiber diameters, esterase activity, and fiber type distributions between three groups (BASE, RESTRICT, and REHAB). The extreme body mass loss of 64% in genetically obese Zucker rats resulted in significant tissue weight loss and reduced fiber diameters in the plantaris muscle. Refeeding resulted in larger muscle fiber diameters that approached baseline values but an 11% difference in muscle weight remained and may be due to a decreased fiber number. Esterase activity seemed to indicate an initial fat utilization for the RESTRICT group, followed by suppressed esterase activity in the REHAB group, suggesting increased fat storage. No significant differences were found in fiber type distribution between BASE, RESTRICT, or REHAB animals.

Soluble fiber and serum lipids: a literature review.

Although fiber has been increasingly recognized as an important dietary constituent, controversy and confusion still exist about the physiologic effects of fiber. Specifically, the independent ability of dietary fiber to lower serum lipid levels is controversial. The purpose of this article is to review available evidence regarding the impact of soluble fibers on serum lipid levels. Soluble fibers appear to have a greater potential to alter serum lipid levels than do insoluble fibers. Significant reduction in the level of serum total cholesterol by soluble fiber was found in 68 of the 77 (88%) human studies reviewed. Of the studies measuring low-density lipoprotein cholesterol, 41 of 49 (84%) reported significant reductions. No significant changes were reported in 43 of the 57 (75%) studies that reported high-density lipoprotein cholesterol and/or in 50 of the 58 (86%) studies that measured triglyceride levels.

Environmental control of energy metabolism in rats.

Food availability was arranged so that episodes of feeding were separated by long periods of deprivation. Distinctly different contexts were associated with each condition. For other animals, relatively short periods of deprivation stood in contrast to relatively long opportunities to free-feed, and were also embedded in widely differing physical contexts. These temporal relationships among the conditions were adjusted to sharpen the saliency of each metabolic condition and thereby enhance its associability with the distinctive environment in which each occurred. To avoid the possibility of circadian entrainment, the feeding or deprivation episodes occurred at unpredictable times according to a variable-time schedule. Following several training cycles and an extended period of free-feeding in a neutral environment, the animals were reexposed to the various contexts and sacrificed for metabolite assays. The environment predictive of feeding elevated adipocyte lipoprotein lipase activity and lowered the levels of serum free fatty acids. The deprivation context boosted serum triglycerides and blood urea nitrogen. The conditioned responses were all of a compensatory nature: Feeding cues resulted in accelerated caloric deposition, deprivation cues elicited conditioned mobilization of stored energy. While protein catabolism and several indices of fat metabolism appear to be conditionable, no evidence of environmental control of glycemic responses was observed.

Effects of diet on norepinephrine turnover in obese (ob/ob) mice.

Effects of energy restriction and of supplemental sucrose or fat on norepinephrine (NE) turnover in brown adipose tissue (BAT) and heart of female obese (ob/ob) and lean mice were examined. Rates of NE turnover in BAT of control female obese mice (8 weeks old) were 39% lower than in control lean mice; no differences were evident in hearts of these mice. Energy intake of 6-week-old ob/ob mice was restricted to the intake of lean mice for 2 weeks. This restriction decreased intake by 41% and reduced rates of NE turnover in heart (-15%), but not in BAT, of obese mice. Next, 7 1/2-week-old lean and obese mice were given access to stock diet and a 30% sucrose solution for 3-4 days. Intake of stock diet decreased by more than 50%. Total energy intake increased in lean mice (+18%), but decreased (-19%) in obese mice. When a 10% sucrose solution was offered intake of stock diet still decreased, but total energy intake was unchanged in lean and obese mice. Oxygen consumption increased in lean mice (+19 to +24%), but not in obese mice, when fed either 30 or 10% sucrose solutions, or a fat-supplemented diet where fat isocalorically replaced the sucrose consumed from 30% sucrose solution. Rates of NE turnover were not significantly increased in lean mice fed the 30% sucrose solution, but were increased in BAT (+34%) and heart (+25%) in lean mice fed the fat-supplemented diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of thyroxine on Na+,K+-ATPase and norepinephrine turnover in brown adipose tissue of obese (ob/ob) mice.

Thyroxine treatment improves some of the defective thermogenic properties of obese (ob/ob) mice. Because brown adipose tissue (BAT) is an important thermogenic organ in mice, effects of thyroxine treatment on Na+, K+-ATPase, a thyroid-hormone responsive enzyme, and on rates of norepinephrine (NE) turnover, an indicator of sympathetic nervous system activity, in BAT of lean and obese mice were evaluated. Female mice, six weeks old, were injected with approximately 4 micrograms thyroxine daily for 2 weeks. Numbers of Na+, K+-ATPase enzyme units in BAT were similar in control lean and obese mice. Thyroxine treatment increased numbers of Na+, K+-ATPase enzyme units by 60% and 100% in lean and obese mice, respectively, indicating that the BAT of obese mice was responsive to thyroxine treatment. Fractional rates of NE turnover were 75% faster in BAT of control lean mice than in obese mice. Thyroxine treatment decreased functional rates of NE turnover in BAT of lean mice by 35%, but had no effect on NE turnover in BAT of obese mice. Rates of NE turnover in heart and pancreas of control lean and obese mice were unaffected by phenotype. Although the decreases in fractional rates of NE turnover in heart (-23%) and pancreas (-11%) of lean mice in response to thyroxine injections were not statistically significant, the calculated rates of NE turnover (fractional rate of NE turnover times the NE content of the organ) in these organs of lean mice were decreased 25% to 30% (P less than 0.05) in response to thyroxine. Thyroxine injections did not affect NE turnover in either heart or pancreas of obese mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Norepinephrine turnover in obese (ob/ob) mice: effects of age, fasting, and acute cold.

The possibility that low sympathetic nervous system (SNS) activity in brown adipose tissue (BAT) of 8-wk-old obese (ob/ob) mice results from their gross obesity at that age was investigated. Norepinephrine (NE) turnover, an estimator of SNS activity, was measured in BAT and other organs of 2-wk-old preobese ob/ob mice, and at 4 and 8 wk of age. Rates of NE turnover were 36% slower in BAT of preobese ob/ob mice than in lean littermates and remained slow in their BAT at 4 (-66%) and 8 (-56%) wk of age. In heart, rates of NE turnover were 48% slower in preobese ob/ob mice than in lean littermates, but the difference diminished at 4 (-21%) and 8 (-16%) wk of age. Rates of NE turnover in white adipose tissue, liver, and pancreas of obese mice were generally comparable with rates in these organs of lean mice. Effects of fasting (24 h) and acute cold exposure (14 degrees C for 8 h) were also examined. In general, fasting lowered and cold exposure elevated NE turnover equally in obese and lean mice. Ob/ob mice housed at 23-25 degrees C exhibit low SNS activity in their BAT prior to the onset of gross obesity, even though SNS activity in their BAT responds normally to an acute cold stress. This low SNS activity probably contributes to their subsequent high efficiency of energy retention.

Reduced norepinephrine turnover in brown adipose tissue of ob/ob mice.

Obese (ob/ob) mice have a lower thermogenic capacity than lean mice. The possible role of brown adipose tissue (BAT) in this defect was investigated. Lean and obese mice were exposed to 33 (thermoneutral), 25, or 14 degrees C for up to 3 wk. BAT cytochrome oxidase activity and numbers of Na+-K+-ATPase enzyme units, enzymes involved in thermogenesis, were similar at 33 or 25 degrees C. Chronic exposure to 14 degrees C increased these enzymes 34 and 62%, respectively, in lean mice and nearly 150% in obese mice. Sympathetic nervous system activity, which stimulates thermogenesis in BAT, was evaluated by measuring norepinephrine (NE) turnover. At 25 degrees C, NE turnover rate in BAT of obese mice was only 40% as rapid as in BAT of lean mice. Chronic exposure to 33 degrees C depressed NE turnover in BAT of lean mice, but not in obese mice, whereas exposure to 14 degrees C accelerated NE turnover in both lean and obese mice. Lower sympathetic nervous system activity in BAT of obese mice at 25 degrees C is likely a major factor in their reduced nonshivering thermogenesis and resultant high efficiency of energy storage.

Reduced sympathetic nervous system activity in rats with ventromedial hypothalamic lesions.

To determine if alterations in sympathetic nervous system (SNS) activity occur in rats with ventromedial hypothalamic (VMH) lesions, norepinephrine (NE) turnover rates were examined in various tissues of lesioned and control, weanling rats. VMH-lesioned rats fed a high-carbohydrate diet ad libitum for 4 weeks following surgery were not hyperphagic, but they gained 50% more body energy than control rats. VMH lesions extended the half-life of 3H-NE in interscapular brown adipose tissue (BAT) by 42%, in abdominal white adipose tissue (WAT) by 201%, in heart by 61% and in pancreas by 85%, and reduced total NE turnover (ng/organ/hr) in BAT (38%), WAT (57%), heart (30%) and pancreas (53%). Reduced SNS activity in BAT is consistent with the decreased energy expenditure (heat production) and increased energy efficiency observed in VMH-lesioned rats. In WAT, decreased SNS activity coupled with hyperinsulinemia would facilitate energy storage as fat by reducing lipid mobilization. In the pancreas, reduced SNS activity would contribute to hyperinsulinemia. These results support the hypothesis that VMH lesions decrease SNS activity in several organs. This change in autonomic tone is very likely a major factor in the development of obesity in VMH-lesioned animals.

Intestinal microflora in the guinea pig as observed by scanning electron microscopy. Effect of fibrous dietary supplements.

The gastrointestinal ecosystems of weanling guinea pigs fed a purified diet with and without supplements of cabbage, alfalfa and holocellulose were examined by scanning electron microscopy. The diets, which were based on soybean protein, sucrose and wood cellulose, were fed for 28 days and the mucosa and associated microbes were fixed in situ. Bacteria, rods and cocci being the predominant morphological types, were commonly observed on the epithelial surface of the jejunum and ileum and much less frequently in the duodenum. In the cecum, fusiform- and spiral-shaped organisms were the most common types. The fusiforms, which produced unique indentations in the intestinal mucosa, were found in the intestines of the cabbage and alfalfa-supplemented guinea pigs but not in those fed the basal diet. There was considerably less mucus on the intestinal epithelium when the cabbage supplement was supplied. Whether promotion of the fusiform population or elimination of the mucus secretion are causally related to the growth stimulating properties of the supplements is not clear, but the results suggest a relationship.

An unrecognized dietary factor for guinea pigs associated with the fibrous fractions of plant products.

The growth rate of guinea pigs was used to assess the nutritional value of plant materials and to characterize the active component(s). Weanlings were fed for 28 days a purified diet based on soybean protein. Addition of 10 to 20% of wood pulp improved the growth rate beyond that supported by 0 to 5%. Subsequently, the basal diet contained 15% of wood cellulose. Raw cabbage, ad libitum, 5% of wheat straw and 5% of mature alfalfa, collected and dried in the laboratory, increased growth rate significantly. Several other plant products tested were inactive. Holocellulose (2.5%) prepared from alfalfa improved the growth rate while that from cabbage was minimally active. Afalfa holocellulose fractions enriched in hemicellulose and alpha-cellulose were inactive. Lyophilized cabbage and the residue which remained after extraction of frozen raw cabbage with ethyl acetate and acetone stimulated growth when fed at a level of 10%. Treatment of holocellulose with KOH, with pancreatin at pH 8 or with 0.1 m KHCO3 caused loss of activity. Storage of dry alfalfa meal for a period of 1 year resulted in loss of activity. It is concluded that a labile component of alfalfa associated with the fibrous fraction confers unique nutritional value to the fiber. Cabbage also contains a labile growth stimulant which may be associated with the fibrous fraction.