Exercise training and severe caloric restriction: effect on lean body mass in the obese.

The purpose of this study was to investigate the effects of exercise intensity on the body composition of obese subjects during severe caloric restriction. Forty obese subjects (33 women, 7 men; 41 +/- 7.7 years; 106 +/- 26kg; body fat > 25% men, > 30% women) on a commercially prepared OPTIFAST 420kcal/day supplemented fast were randomized into groups that exercised at target heart rates corresponding to 40% and 60% of the heart rate reserve (HRR) at the start of the program. Training volume was similar for both groups at approximately 300kcal per session three times per week for 12 weeks. Body weight, body fat, and lean weight were similar for both exercise intensity groups at week one. Overall, body weight decreased by 15.3 +/- 6.7 kg (p < or = .05), and body fat decreased by 14.9 +/- 5.0 kg (p < or = .05) for the 40 subjects, whereas lean weight remained unchanged. No significant differences in body weight, body fat, or lean weight were observed between the two groups. The results of the current study indicated that while on a supplemented 420-kcal/day fast, exercise at 40% and 60% of the HRR affected body composition similarly when total training volume was held constant at 900kcal/week. Lean weight remained unchanged and accompanied a 14.9 +/- 5.0-kg decrease in body fat, which may have resulted when the volume of exercise (ie, 900kcals/wk) was factored into the exercise prescriptions. These results suggest that exercising at 60% of the HRR offers no advantages for body composition changes over those obtained from exercising at 40% of HRR when the total volume of exercise training is controlled.

Moderate exercise in young female S5B/P1 rats does not reduce body fat.

Weanling S5B/P1 female rats were divided into four groups as follows: high fat diet, exercised (FE); high fat diet, unexercised (FU); high carbohydrate diet, exercised (CE); and high carbohydrate diet, unexercised (CU). After 25 days of progressive training, exercised rats ran on a motor-driven treadmill for 30 days at 25 m/min per 1 h at 0 degree grade for 6 days a week. Rats were weighed weekly throughout the experiment and food intakes were recorded for the last 3 weeks of the experiment. After euthanasia at 15 weeks of age, three muscles, liver, heart, kidney, 3 fat depots, and tibia-fibula were dissected out and weighted. The carcass, including weighted organs and fat depots, was analyzed for body fat. Exercised rats, regardless of diet, weighed slightly but significantly more than unexercised rats. They also tended to eat more food and to have a higher quantity of fat-free body mass than unexercised rats. Percent body fat was similar for exercised and unexercised rats. The tibia weighed significantly more (p less than 0.05) in CU than in FU rats but the weight was similar in CE and FE rats. The density of the tibia was significantly higher (p less than 0.01) in exercised than in unexercised rats.

Effect of carbon tetrachloride on hamster tracheal epithelial cells.

This study was designed to assess effects of carbon tetrachloride (CCl4) in hamster tracheal epithelium. Adult, male, Syrian golden hamsters were treated with 2.5 ml/kg CCl4 ip, and controls received only the vehicle (peanut oil). Animals were sacrificed after 1, 4, 12, and 24 h. Tissue samples from upper and lower tracheal levels were fixed and embedded in glycol methacrylate for light microscopy. Some tracheal rings were also fixed in formaldehyde/glutaraldehyde cacodylate buffer for transmission electron microscopy. For histopathologic evaluation of the tracheal epithelial cells, each tracheal level was cut transversely at 3 microns and stained with toluidine blue. CCl4 produced injury to ciliated and nonciliated cells in all portions of hamster trachea, although the severity of CCl4-induced injury differed in various levels and regions. The number of damaged cells increased markedly after 1 h in the lower trachea, but not until after 4 h in the upper trachea. By 24 h, the number of injured cells had decreased so that no significant difference from control was evident. The ultrastructural alterations in epithelial cells were obvious as early as 1 h after CCl4 administration. Intracellular organelles, including smooth and rough endoplasmic reticulum, mitochondria, and Golgi apparatuses, were damaged by this chemical. Since CCl4-induced cell injury is dependent on metabolism by intracellular NADPH-dependent cytochrome P450 monooxygenases, these results suggest that hamster tracheal epithelial cells have the potential to activate CCl4 metabolically.

Plasma and erythrocyte magnesium concentrations and correlations with maximum oxygen consumption in nine- to twelve-year-old competitive swimmers.

Twenty-two competitive swimmers (9 males, 13 females) were compared with 18 controls (11 males, 7 females) for body composition, intakes of selected nutrients, VO2max, hemoglobin, hematocrit and magnesium concentrations in plasma, erythrocytes and whole blood. Subjects ranged in age from 9.5 to 12.9 years. Male swimmers had 6.5% less body fat than did male controls (p less than 0.05) whereas there was no significant difference in body fat between female swimmers and controls. Energy, protein and magnesium intakes for swimmers and controls of the same gender were similar. VO2max was significantly higher in swimmers than in controls for both sexes. Magnesium concentrations in plasma, erythrocytes and whole blood were similar for swimmers and controls. However, concentrations of magnesium expressed as milligrams/deciliter in plasma were 8% higher in male swimmers than in female swimmers (p less than 0.05). There was a significant (p less than 0.05) positive correlation between plasma magnesium and VO2max in males, r = +0.42, but not in females.

Pathogenic Weight-Control Behaviors of Young Competitive Swimmers.

In brief: To study the use of weight-modification techniques by young swimmers, data were collected from 487 girls and 468 boys, aged 9 to 18, at a competitive swimming camp. The survey revealed that (1) many young swimmers had misperceptions about their body weights, with girls particularly likely to misperceive themselves as overweight; (2) swimmers' decisions to lose or gain weight were based on their perceptions more than on their actual weights; (3) opinions of others strongly influenced swimmers' opinions of their own weights; and (4) 15.4% of the girls (24.8% of postmenarcheal girls) and 3.6% of the boys used pathogenic weight-loss techniques. The swimmers' concerns about weight seemed to be more related to societal influences than to the demands of their sport.

Postnatal muscle fibre histochemistry in the rat.

Histochemical techniques were used to study the postnatal muscle fibre differentiation patterns in the plantaris and soleus muscles of male Sprague-Dawley rats. Nine groups of animals (n = 6/group) were killed at 1, 6, 11, 16, 21, 26, 31, 36, and 140 days of age. Serial transverse sections of the two muscles were stained with H & E, NADH-D, and myofibrillar ATPase with acid (pH 4.35) or alkali (pH 10.4) preincubation. In each of the age groups, all available fibres across the muscle sections were classified. Obtained data show that fibre types are basically undifferentiated at birth in both muscles. In the plantaris muscle there are about 99% type IIA and less than 1% type I fibres at 6 days of age. Type IIB fibres can be identified at 11 days of age. There are increases in the percentages of type I fibres (from 0.7% to 3.5%) and type IIB fibres (from 1.1% to 6.5%) between 6 and 11 days and between 16 and 21 days respectively. By 36 days of age the relative numbers of type IIA, IIB, and type I fibres in the plantaris are approximately 80%, 14%, and 6%, respectively. A gradual change in fibre-type composition continues until it becomes 47% for type IIA, 43% for type IIB, and 10% for type I at 140 days of age. In the soleus muscle there are approximately 73% type IIA and 26% type I fibres at both 6 and 11 days of age. However, type IIA fibres decrease to 44% and type I fibres increase to 56% at 16 days of age. This rapid shift in fibre composition continues up to 31 days of age when the distribution becomes 25% for type IIA and 74% for type I fibres. Thereafter, the differentiation rate is much slower. At 140 days of age, there are 17% type IIA and 83% type I fibres in the soleus muscle. The results of this study show that the fibre populations in the plantaris and soleus muscles of the rat undergo a postnatal differentiation process. In both muscles the adult fibre population is established by 140 days of age. Although relatively rapid increases of type I and type IIB fibres occur in the plantaris during the second and third weeks of life, differentiation in that muscle appears to be an essentially continuous process. There is a notable shift in the fibre composition of the soleus muscle during the second postnatal week. Differences between the patterns of differentiation in the two muscles are apparent.

Activity-induced morphologic changes in rat soleus nerve.

The effects of 8 to 12 weeks of intense running or swimming on the morphology of the soleus nerve of the adult male albino rat were investigated. Nerve fiber diameter and number, axon diameter, and myelin area were determined. Mean fiber diameter (5.50 +/- 0.47) of the trained rats was smaller (P less than 0.05) than for sedentary control rats (6.19 +/- 0.27). The decrease in fiber size in the trained rats appeared to be reflected by a combination of smaller (P greater than 0.05) mean axon diameter and myelin area. Total fiber number was not different in the control (means = 113 +/- 6) and trained (means = 108 +/- 4) rats. These results provide further evidence that a chronic, intense but physiologic exercise can impose a functional demand on peripheral nerves that can alter morphologic features that are closely related to conduction velocity and commonly are associated with neuronal cell size.

Differential effects of running and weight-lifting on the rat coronary arterial tree.

Twenty-four postpubertal male albino rats were assigned randomly to sedentary-control (C), endurance-running (ER), and weight-lifting (WL) groups to study the effects of different chronic-exercise regimens on precapillary vascularity in the heart. The exercise routines were administered 5 d/wk. At the end of either 8 or 16 wk of treatments, half of the animals in each group were anesthetized. A 12% vinyl acetate solution was injected into the coronary arteries of each anesthetized animal at a pressure of 300-350 mmHg, through the ascending aorta. The injected hearts were removed and weighed. A 10% potassium hydroxide solution was used to digest tissues from the vinyl cast of each coronary arterial tree. No differences in absolute or relative heart weights were observed between the control and trained groups. When compared to the control group, the ER animals had heavier left and total coronary cast weights and higher total cast weight-to-heart weight ratios (P less than 0.05). Although an overall increase in precapillary vascularity of the heart was evident in the endurance-trained ER animals, none was found in the strength-trained WL group. However, the WL animals had significantly increased right coronary cast weights, and their ratios of right coronary cast weight to total cast weight also were higher than those of the control animals (P less than 0.05).

Skeletal muscle fiber splitting with weight-lifting exercise in rats.

Adult male albino rats were assigned randomly to control (CON) and weight-lifting (WL) groups. The WL rats were subjected to a progressive weight-lifting program against high resistance for 8 weeks. During the last 2 weeks, each WL rat lifted a load equal to 130% of its body weight. The mean weight of the adductor longus muscle was significantly increased in the WL group ( p < 0.05). This increased muscle weight was shown to be due to an increase in the number of fibers per unit cross-sectional area ( p < 0.05), and the mean sizes of both fast-twitch oxidative glycolytic and slow-twitch oxidative fibers were significantly smaller in the WL rats than in the CON rats (p < 0.05). Light and electron microscopic examination showed that five out of eight WL rats exhibited longitudinally split muscle fibers, while only one CON rat had a few centrally placed nuclei. The splitting process appeared as either a "pinching-off" of a small segment from the parent fiber or an invagination of the sarcolemma deep into the muscle fiber in a plane parallel to the sarcomeres. There were preliminary indications that this work-induced fiber-splitting process may be a physiological adaptation of muscle to the stress of exercise.

Effects of an anabolic steroid and sprint training on selected histochemical and morphological observations in rat skeletal muscle types.

The effects on selected histochemical and morphological parameters of anabolic steroid administration and of high-intensity sprint running, separately, and in combination, were studied in young adult male rats. Dianabol (methandrostenolone) 1 mg/day for 8 weeks had no significant effects on phosphorylase or glycogen staining intensities and on fiber area in skeletal muscles of either trained or sedentary animals. The program of sprint training resulted in significantly decreased intensities of phosphorylase in all ten regions of the gastrocnemius, plantaris, and soleus muscles that were studied. Glycogen localization was significantly increased with training in five regions of the gastrocnemius and plantaris muscles which contained predominantly fast-switch fibers. No changes in fiber area occurred with the training program. We conclude from these results that (a) normal androgen levels in young, healthy male animals are sufficiently high so that the intake of large doses of anabolic steroid does not result in the stimulation of glycogen metabolism or hypertrophy of skeletal muscle; (b) the changes induced by high-intensity, short-duration sprint training suggest that the existing glycolytic capacity of muscle is adequate to supply the muscles energy needs even during the stress of very strenous exercise, and that more fast-twitch fibers were recruited by the exercise regimen than slow-twitch fibers.

Skeletal muscle enzyme alterations after sprint and endurance training.

Specifically designed programs of sprint and endurance running were used to determine how different types of training affect enzyme activities in selected energy metabolism pathways. Three types of rat skeletal muscle were studied. After 8 wk of training, small but significant decreases in lactate dehydrogenase activity (15%) were found in the soleus and white vastus lateralis muscles of the sprint animals. Decreased levels of phosphoglucomutase and lactate dehydrogenase (approx. 20%) of the white vastus lateralis muscles of the endurance group were observed at the same time. By 16 wk of training, fumarase activity increased approximately twofold in the white vastus muscles and 45% in the soleus and plantaris muscles of the endurance group. Similarly, increased fumarase activity (42%) was seen in the soleus muscles of the sprint group. In all muscles, phosphoglucomutase and lactate dehydrogenase activities generally were lower in the endurance animals than in the control animals. No significant differences were found between the sprint and endurance groups at either or sixteen weeks of training. These results suggest that similar enzyme adaptations occur over time with both types of training.

Effects of dianabol and high-intensity sprint training on body composition of rats.

The effects on body composition and organ weights of anabolic steroid administration and of high-intensity sprint running, separately and in combination, were studied in young adult male rats. Dianabol (methandrostenolone) 1 mg/day for 8 weeks had no significant effects on muscle weight or lean body mass in either the trained or the sedentary animals. The program of sprint training resulted in a lower body weight, a lesser percentage of body fat (Runners, 8.5%, vs. sedentary, 13.5% P less than 0.01) and a greater relative lean body mass (runners, 91.5% vs. sedentry, 86.5%, P less than 0.01). We conclude from these results that (a) normal androgen levels in young, healthy male animals are sufficiently high so that the addition of a large dose of anabolic steroid does not result in stimulation of additional muscle growth, and (b) the changes in body composition induced by high-intensity, short-duration sprint training are qualitatively similar to those seen with endurance exercise training.

Skeletal muscle function and structure after depletion of creatine.

Experiments were conducted to determine if normal skeletal muscle function and structure are dependent upon their ability to store large quantities of metabolic energy in the form of N-phosphorylcreatine. Muscle levels of creatine and N-phosphorylcreatine were reduced by feeding young male rats diets containing 1 per cent beta-guanidinopropionic acid (beta-GPA). Muscle function was evaluated by monitoring performance during a 4-week, short duration, high intensity exercise program in a control running wheel. Structural effects were determined by histochemistry, morphometric analysis, and routine histologic procedures using light microscopy. Evidence of abnormal creatine metabolism of rats fed beta-GPA included: excessive creatinuria, reduction in urine creatinine, reduced levels of muscle and brain creatine, and a reduced activity of muscle creatine kinase. In separate experiments, beta-GPA inhibited the reaction of creatine with creatine kinase in vitro. When muscle function was evaluated by running, the percentage of expected revolutions for the group of rats fed beta-GPA was below the expected normal values. The white (type II) fibers from the gastrocnemius of exercised rats fed beta-GPA were smaller than fibers from the same muscle areas of rats fed normal diets. The histochemical characteristics of red (type I) and white fibers of all rats tested were within normal limits. It is concluded that feeding beta-GPA will result in structural and functional changes in skeletal muscles of exercised young male rats. These changes are believed to result from the ability of beta-GPA to block creatine entry into muscle and thereby prevent muscle from accumulating and maintaining its normal complement of creatine and N-phosphorylcreatine.