Dietary protein does not affect overloaded skeletal muscle in rats.

We compared the effects of three levels of dietary protein, i.e., 7% (low protein; LP); 17.5% (adequate protein; CON); or 30% (high protein; HP) on growth of functionally overloaded muscle in Sprague-Dawley male rats. Growth of plantaris and soleus muscles was induced by the surgical removal of gastrocnemius muscles in one hindlimb; muscles in the other leg were used as sham-operated, intra-animal controls. After 4 wk, rats fed the 7% LP diet gained less weight (-29%) and had lighter livers (-20%) and kidneys (-16%) than rats fed the CON diet (P < 0.05). Measurements of rats fed the 30% HP diet were not different from those of CON rats except that their kidneys were larger (+6%) (P < 0.05). The level of dietary protein did not affect the experimentally induced muscular growth in either plantaris or soleus muscles. Gains in overloaded plantaris muscles over sham-operated muscles were not different among rats fed LP, CON and HP diets for muscle mass (+42 to +45%), total protein (+42 to +46%) and myofibrillar protein (+40 to +44%). Soleus muscles also did not differ among diet groups for gains in mass (+20 to +33%), total protein (+20 to +33%) and myofibrillar protein (+21 to +33%). No dietary protein effects were found on myosin heavy chain isoform (I, IIa, IIx, IIb) expression in either plantaris or soleus muscles. We conclude that gains in plantaris and soleus muscle mass, total protein and myofibrillar protein induced by functional overload are not affected by low (7%) or high (30%) protein feeding in young male rats for 4 wk.

Utilization of bioelectrical impedance to predict carcass composition of Holstein steers at 3, 6, 9, and 12 months of age.

The objective of this experiment was to study the usefulness of bioelectrical impedance analysis (BIA) in determining soft tissue composition (STC) and carcass fat-free mass (CFFM) of Holstein steers at different ages. Growth data and prediction of STC and CFFM were determined for four groups of Holstein steers: 12 of 3 mo, 12 of 6 mo, 15 of 9 mo, and 16 of 12 mo of age. Average weight for animals at 3, 6, 9, and 12 mo were 96.6, 204.7, 354.1, and 465.9 kg, respectively. Average fat content of carcass soft tissue at 3, 6, 9, and 12 mo were 2.6, 9.8, 18.2, and 24.6%, respectively. Average protein content of the carcass soft tissue was 20.7% at 3 mo, 20% at 6 mo, 18.30% at 9 mo, and 16.9% at 12 mo of age. Feed and water were withheld for 20 h before the BIA was applied. Steers were sedated and forced to recumbency in a lateral position on their right sides over a nonconductive surface. Two electrodes were placed on each limb of the right side (metatarsal and metacarpal regions on back and front foot, respectively). Resistance (Rs) and reactance (Xc) were obtained by attaching four terminals to the electrodes. Impedance and other predictors such as Vol1 (L/Rs), Vol2 (L2/(RS2+Xc2).5, Vol3 (geometrical animal volume), L (2 x height + body length), and L2 were calculated from Rs and Xc, and body measurements and were used to generate prediction equations for CFFM and carcass soft tissue composition. Carcass fat-free mass was predicted accurately for all age groups and the pooled data (r2 = .99 at 3 mo, .99 at 6 mo, .97 at 9 mo, .77 at 12 mo, and .98 for the pooled data). Correlation coefficients between impedance readings and CFFM and carcass composition were calculated. Carcass CFFM and kilograms of H2O for the pooled data (across age groups) were both correlated highly to Vol1 (.97), Vol2 (.95), L (.97), and L2 (.97).

Body fat deposition: effects of dietary fat and two exercise protocols.

OBJECTIVE: We evaluated the effects of two levels of dietary fat (0 and 20g beef tallow/100g diet) and two treadmill exercise protocols (low-intensity, high-intensity) on fat deposition in rats. DESIGN: Male Wistar rats (n = 50) remained sedentary or were forced to run 840 meters/day, 5 days/week, on a rodent treadmill. Those on the high-intensity protocol covered this distance in less time (38 min) than those on the low-intensity program (60 min). Responses to high-fat (HF) and low-fat (LF) diets were compared within each exercise group for this 8-week study. RESULTS: High fat feeding, as a single factor, did not affect energy intake, carcass fat, intramuscular fat, or fat associated with any tissue studied. The HF diet also did not affect responses to either exercise protocol. The high-intensity-exercised animals had less carcass fat (LF: 21% less; HF: 33% less), smaller omental fat pads (LF: 20% less; HF: 37% less), and retroperitoneal fat pads (LF: 19% less; HF: 38% less), and lower serum triglyceride levels (LF: 26% less; HF: 41% less) than sedentary rats. Those differences were less marked for the low-intensity-exercise rat. Neither mode of exercise or diet affected lipid concentrations in hindlimb muscles, livers, hearts, or kidneys. CONCLUSION: Exercised animals generally had less fat deposition than sedentary rats but this was more pronounced for high-intensity than low-intensity-exercised rats, and was not affected by feeding a 20% beef tallow diet.

Commercially marketed supplements for bodybuilding athletes.

We conducted a survey of 624 commercially available supplements targeted towards bodybuilding athletes. Over 800 performance claims were made for these supplements. Supplements include amino acids, boron, carnitine, choline, chromium, dibencozide, ferulic acid, gamma oryzanol, medium chain triglycerides, weight gain powders, Smilax compounds and yohimbine. Many performance claims advertised were not supported by published research studies. In some instances, we found no research to validate the claims; in other cases, research findings were extrapolated to inappropriate applications. For example, biological functions of some non-essential compounds were interpreted as performance claims for the supplements. Claims for others were based on their ability to enhance hormonal release or activity. We suggest that more research be conducted on this group of athletes and their nutritional needs. Furthermore, the effectiveness and safety of supplements merit further investigation.

Aspartame- or sugar-sweetened beverages: effects on mood in young women.

Young college women (no. = 120) received, on three different occasions, 12 oz water, aspartame-sweetened beverage, and sugar-sweetened beverage, separated by weekly intervals. Changes in mood were assessed by administering test questionnaires before and 1 hour after the beverages were drunk. Mood tests employed were the Stanford Sleepiness Scale (SSS), the Visual Analogue Mood Scale (VAMS), and the Profile of Mood States (POMS). Changes in mood were similar following consumption of water or the aspartame-sweetened beverage. However, the ingestion of the sugar-sweetened beverage was followed by increased sleepiness during the last half of the one-hour observation period (p less than .002).

The effects of exercise on catch-up growth of rats recovering from early undernutrition.

The effects of an 8-wk exercise program were studied on growth of rats following a period of normal nutrition or undernutrition. Male Wistar weanling rats, underfed by fasting on alternate days for 4 wk, gained 56% as much weight as ad libitum-fed rats (carcass: 47% as much fat; 63% as much lean mass), and had markedly smaller fat depots, visceral organs, brains and hindlimb muscles and bones. Rats in both groups were then allowed free access to feed and subdivided into exercise or non-exercise groups. Eight wk of treadmill exercise (speed, 24 m/min; duration, 75 min/d; frequency, 5 d/sk) reduced weight gain in both normal-fed and underfed rats, but had a greater effect on underfed rats. Underfed rats that were exercised gained 76% as much weight (carcass: 54% as much fat; 92% as much lean mass), and tended to have lighter tissues than underfed rats that were not exercised. Data suggest that treadmill exercise following a postweaning period of undernutrition reduces "catch-up" growth in rats.

Oral contraceptives and fat patterning in young adult women.

PIP: 90 nulliparous white female college students, selected from 2 undergraduate introductory courses at Kansas University, participated in a cross-sectional study designed to compare the fat distribution of oral contraceptive (OC) users to that of nonusers matched for height and weight. The subjects ranged in age from 18-26 years. The 30 OC users had been using the same brand of OCs for an average of 17.7 months (range of 3-36 months) and had not used another brand previously. Each OC user was matched to 2 nonusers. Each subject's height was measured to the nearest cm. A Detecto sliding-weight balance was used to measure body weights of the women (in light clothing) to the nearest 0.1 kg. Circumference measurements also were taken to determine body shape and fat distribution. The waist girth to hip ratio (WHR) also was calculated. Fat distribution of the OC users was similar to that of nonusers matched for height and weight. Both groups were comparable in their circumference and skinfold measurements, except that the OC users had larger axilla skinfolds. Progestational activity of the combined OCs was not associated with any of the physical measurements. Estrogenic activity of the combined OCs was correlated positively with body mass index, arm and thigh circumference, and peripheral fat distribution. Estrogenic activity also was associated weakly with hip and low chest circumferences but no with any of the 7 skinfold thickness measurements. The women taking the higher estrogen OCs were more likely to have circumference measurements consistent with a more gynoid shape. Thigh skinfold thickness was consistent with those findings, though not statistically significant.^ieng

Energy metabolism during exercise at different time intervals following a meal.

The objective of this study was to compare caloric expenditure and substrate utilization during exercise begun at different time intervals following a standard test meal or in the fasted state. Eight physically fit women (aged 21-27 years) participated in four separate exercise trials. In three trials, the subjects consumed a 940-kcal meal following an overnight fast and began exercising either 30, 60, or 90 min after the meal. In the other trial, the subjects did not consume any breakfast prior to exercising. Energy expenditure and substrate utilization were determined by indirect calorimetry during the last 23 min of a 30-min run on a treadmill at an average work load of 62% VO2max. There were no significant differences among trials when comparing the total caloric expenditures (range: 215-219 kcal). However, the subjects oxidized significantly more fat (94.3 kcal) when they exercised on an empty stomach than when they exercised 60 or 90 min after the meal (71.6 and 68.8 kcal, respectively) (P less than 0.05). It was concluded that consumption of a meal prior to exercise does not increase the energy cost of the activity for physically fit women, but it does disrupt the pattern of substrate utilization, reducing the contribution of fat as an energy source.

Menstrual cycle and food cravings in young college women.

The effect of the menstrual cycle on food cravings was examined in a population of 83 young college women during a 6-week longitudinal study. Food cravings and menstrual symptoms were evaluated by measuring subject responses in weekly questionnaires ("craving sheets"). The women were not told that the central objective of the study was to examine the effects of the menstrual cycle on food cravings. The menstrual cycle was divided into four stages: menstrual flow; the first half of the cycle, excluding menstrual flow; the second half of the cycle, excluding the premenstrual phase; and 1 week premenstrual. Cravings for 32 foods were examined on a weekly basis under controlled environmental conditions. Foods tested were categorized according to common characteristics. The women exhibited a greater preference for chocolate foods during menstrual flow than during the other menstrual stages. Cravings for high-sugar foods, high-starch foods, or lower carbohydrate foods were not significantly affected by the stage of the menstrual cycle.

Preexercise feedings of glucose, fructose or sucrose: effects on substrate depletion in rats.

Male Wistar rats (n = 72) trained to run on a treadmill were fasted overnight and fed by gavage 3 ml unsupplemented water or a solution containing 2 g of glucose, fructose or sucrose 30 min prior to exercise. Six rats from each dietary group were killed after 0, 1 or 2 h of exercise. Blood glucose levels decreased in all groups over the 2-h exercise period; however, the largest decline in blood glucose was exhibited by the rats fed unsupplemented water (-32.1%), followed by those fed fructose (-26.9%), sucrose (-13.9%) and glucose (-8.3%). The water-fed control rats also had the largest increase in circulating free fatty acids (+215.4%), followed by those fed fructose (+120.8%), sucrose (+69.2%) and glucose (+57.5%). The fructose-fed animals exhibited the greatest depletion of liver glycogen and the smallest decline in soleus and red vastus lateralis muscle glycogen of the rats fed the different carbohydrates. The data indicate that exercise-induced changes in substrate levels can be modified by the type of carbohydrate given prior to exercise.

Beneficial effects of exercise on growth of rats during intermittent fasting.

An 8-wk trial was conducted to compare the effects of exercise and intermittent fasting, either singly or combined, on growth responses of rats. Four-week-old male Wistar rats, 85-110 g each, were assigned to one of four groups (n = 9): control, exercise on a motor-driven treadmill, fasting every other day (EOD) and fasting EOD and exercise combined. At the end of the trial, the exercised rats had consumed 7% less feed, had gained 7% less weight and had 36% less carcass fat than the control rats. Fasting on alternate days markedly reduced the growth rate of the young rats. Fasted-EOD rats weighed less than half as much as the control rats, had 64% less carcass fat and 51% less lean mass and had smaller livers, kidneys, hearts, tibias and tibialis anterior muscles. The addition of exercise to the fasting EOD regimen improved the growth of the animals. When the fasted-EOD rats were also exercised, they gained 29% more weight, consumed 11% more feed and had carcasses that contained 29% more lean mass and 18% less fat than the fasted-EOD rats. The data suggest that exercise may be beneficial where feed restriction is episodic, allowing some capacity for catch-up growth.

Weight control in young college women: who are the dieters?

Dieting behavior was studied in 166 young college women, 18 to 24 years old. The women were divided into three groups on the basis of the amount of time they had spent dieting during the previous school year (8 months). Of the whole population, 18.1% had spent more than half the time dieting (chronic dieters), 45.2% had dieted 50% of the time or less (periodic dieters), and 36.7% had not dieted during that period (nondieters). Physical measurements, background characteristics, and weight-loss experiences were compared among the three groups, following an anthropometric measurement session and administration of a self-report questionnaire. The chronic and periodic dieters weighed an average of 12 lb more than the nondieters and were more likely to be obese. The dieters also had greater triceps skinfold thickness, arm circumference, arm muscle diameter, and arm muscle circumference measurements. Women in both dieting groups were more likely than the nondieting group to consider themselves as having been overweight during their childhood and adolescent years and to consider at least one parent overweight. The average age at the time of the first reducing diet was 16.2 years. The four most commonly tried weight-loss approaches were exercise, moderate calorie restriction, fasting/starvation, and diet pills or supplements. The major sources of information on reducing diets were magazines or newspapers and friends or relatives.

Effect of exercise duration on feed intake and body composition of Swiss albino mice.

The purpose of this study was to examine the effects of daily exercise of varying duration on the body composition, weight, and feed intake of mature Swiss albino mice. Fifty-four male mice were equally divided into a control group and five exercise groups (n = 9) performing 20, 40, 60, 120, and 240 min of daily exercise on a treadmill (7.2 m/min). Feed intake and body weight were measured weekly for 10 wk. At the completion of the study the mice were killed and the animal carcasses were chemically analyzed for fat, dry matter, and protein content. The results of this study demonstrate no differences in the body weight among groups (P less than 0.97) with all groups gaining 4.5-5.8 g during the 10-wk period. However, fat content decreased significantly from 15.7% in the control to 12.0% in the 120- and 240-min exercise groups (P less than 0.05). In contrast, protein content showed an insignificant rising trend from 13.0 to 14.6% with increasing duration of exercise. Feed intake showed a nonsignificant drop during the 20-min exercise treatment and remained unchanged among groups. These data show a slight but variable appetite-suppressing effect of light exercise in mice accompanied by favorable body composition changes even in the absence of differences in body weight. These findings suggest the mouse to be an acceptable experimental model for body composition and exercise studies.

Gastric emptying in exercised mice.

Male adult mice were fasted for 8-10 hr, given a 1% phenol red marker solution, and exercised on a treadmill. Mice exercised at 0.50 mph had significantly faster gastric emptying rates after 15 min of exercise than non-exercised mice; however differences were not significant for longer periods of time. Mice exercised at 0.25 mph did not have significantly different gastric emptying rates at any time interval studied. Larger volumes empty faster than smaller volumes from stomachs of exercised mice.

Essential fatty acid status and characteristics associated with colostrum-deprived gnotobiotic and conventional lambs. Growth, organ development, cell membrane integrity and factors associated with lower bowel function.

A factorial experiment involving gnotobiotic (GN) and conventional (CV) colostrum-deprived lambs and diets formulated to be adequate or deficient in linoleic acid was conducted to determine the effect(s) of the intestinal microflora on the essential fatty acid (EFA) status of the host and subsequent physiological consequences, i.e., growth, organ development, cell membrane integrity and lower bowel function. Lambs were obtained by sterile surgical procedures and housed in sterile isolators or in conventional metabolism stalls for 60 d. Skimmed cow's milk with 6% hydrogenated coconut oil and vitamins A, D and E added with and without .32% of the total calories as linoleic acid was homogenized, bottled and autoclaved, then fed to appetite three to four times daily. The GN lambs supplemented with linoleic acid gained significantly faster between 13 and 41 d of age and more efficiently between 27 and 41 d than the other treatment groups. The absence of dietary linoleic acid decreased liver and spleen weights and, in general, suppressed development of organs except the brain. Red blood cell hemolysis was not affected by treatment. Although showing signs of chronic mild diarrhea, the GN neonatal ruminant differed in Cl- concentration and dry matter percentage of its lower bowel contents from the "classic rodent model." The results indicate that neonatal colostrum-deprived lambs have an EFA requirement, as evidenced by decreased growth and performance characteristics in the GN linoleic deficient vs GN supplemented group, and suggests that the required level is in excess of .32% of the total caloric intake as linoleic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of bilateral nephrectomy on selected gastrointestinal bacteria in the rat.

A series of experiments was designed to investigate the influence of acute renal failure on selected gastrointestinal bacteria. Sprague-Dawley male rats were bilaterally nephrectomized to induce acute renal failure, with sham-operated animals serving as controls. After 48 h animals were sacrificed and the stomachs, upper and lower small intestines, ceca, and colons were excised and subjected to microbial analyses. Lactobacilli and streptococci including enterococci, were 1-2 log counts higher in the stomachs of anephric rats than those of sham-operated controls; lactobacilli were increased similarly in the upper small intestines of these animals. Coliforms including Escherichia coli, and Proteus were 1-2 log counts higher in the lower small intestine of anephric rats than those of sham-operated rats. The decreased gastric pH, increased cecal pH, hypothermia, and delayed gastric emptying observed in nephrectomized rats could partly explain the different microfloras in these animals.