ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Laboratory studies using direct calorimetry, a technique which is no longer either rare or difficult, have shown no essential differences between men and women who gain weight easily and the always lean. Both groups gained weight similarly when overeating by 1,000 kcal·d-1. Thermogenic responses to eating and the energy losses in food and urine were similar in the overweight and lean. Daily sedentary energy expenditure is a function of fat-free mass, and fat-free mass increases with obesity. During exercise, calorimetry has shown that heat losses are not always exactly matched to heat production as calculated from respiratory gas exchange, but a 24-h exercise period with a cycle ergometer showed reasonable energy balance when subjects ate as much as they spent. During weight loss from restricting food intake by 1,000 kcal·d-1, calorimetry showed a 12% reduction in sedentary energy expenditure. Based on calorimetry studies and other evidence in the literature, exercise increases energy expenditure, it may eliminate the reduced energy expenditure of caloric restriction, and it can increase muscle mass and thus increase both fat-free mass and daily expenditure.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

A rat model for severe obesity has been developed by feeding the animals a fat-rich, sugar-rich diet. The concentration of fat in the diet was similar to what most Americans consume (about 40% kcal from fat). Calories from sugar was calculated to be 40.6%. As adults, body fat content in these animals averaged 61 or 51 %, depending on whether the fat-rich, sugar-rich diet caused hyperphagia. The rate of body fat accretion in these severely obese rats raised in litters of four was estimated to be 1.78 ± 0.12 (SE) g·d-1(61% body fat) or 0.9 ± 0.03 g·d-1(51% body fat). In contrast, lean rats eating a diet of Purina chow deposited fat at a rate of 0.20 ± 0.02 g·d-1, resulting in a carcass fat content of 18%. Preliminary evidence based on adult body weights of sugar-fed rats suggests that sucrose alone can cause severe obesity similar to that seen with dietary fat alone. Currently, an attempt is being made to determine how dietary fat and/or dietary sugar work to produce severe obesity. One possibility is that dietary fat in the form of a chylomicron and dietary sugar in the form of a very low density lipoprotein may modify adipose tissue lipoprotein lipase activity. This enzyme acts as a gatekeeper for circulating triglycerides entering the adipocyte. It is our belief that the results obtained will help to lay the groundwork for determination of the role of exercise in weight control.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Current knowledge about the thermic effects of exercise in lean and obese subjects and the relationships between exercise and food intake, resting metabolic rate, and dietary-induced thermogenesis were reviewed. Studies of the effects of carbohydrate restriction during low calorie diets on the capacity to perform physical exercise and of the effects of weight reduction with or without the addition of physical training on the metabolic abnormalities of non-insulin-dependent diabetes mellitus are also described.The metabolic efficiency of physical work is normal in obesity, total energy expenditure is increased because of increased body mass, and increased energy expenditure is not necessarily matched by a compensatory increase in caloric intake. Thus, increased physical activity can be expected to result in negative energy balance in obese subjects.It is not clear whether exercise increases resting metabolic rate, but there is considerable evidence that exercise may potentiate the thermic effect of food in lean subjects and that this response may be blunted in the obese.The capacity to perform moderate-intensity exercise during carbohydrate-restricted, low caloric diets is maintained after a period of adaptation, but the capacity for high-intensity exercise (>70% &OV0312;O2max) is decreased unless adequate carbohydrate is provided to maintain muscle glycogen stores. The major effect of the addition of a program of physical training to dietary restriction and weight reduction in the treatment of non-insulin-dependent diabetes mellitus is an increase in peripheral sensitivity to insulin, primarily due to increased non-oxidative glucose disposal in muscle tissue.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The management of the extremely obese patient is best accomplished by a multidisciplinary approach which includes exercise training as an integral component. While diet alone is a potent factor in improving the metabolic complications associated with obesity, the combination of diet and exercise training can further improve these complications and greatly enhance cardiorespiratory function. Although the fitness of extremely obese people is low, individualized exercise programs can be used to safely and progressively train these patients, reduce fatigue, and greatly increase maximum work tolerance.Additional benefits derived from exercise training include improved insulin-mediated glucose utilization, lower serum lipid concentrations, and improved psychological distress scores and anxiety levels.Thus, exercise training can contribute to the success of a weight reducing program by improving metabolic, cardiorespiratory, and psychological factors. Additional important interventions in a multi-disciplinary treatment of severe obesity include psychiatric, psycho-social, and vocational counseling.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Several physiological and psychological benefits can be achieved with exercise training provided an adequate exercise threshold is reached. In recommending exercise regimens to obese individuals, it is important to consider the exercise intensity, frequency, and duration that is most likely to lead to the desired benefits of exercise training. The special problems that some obese individuals may encounter with exercise training should also be considered. Walk/jog and stationary cycling are the two most commonly recommended modes of exercise. Aquatic exercise, due to the buoyancy and thermal properties of water, may be especially suitable as a method of exercise for obese individuals. In addition to swimming, cycling exercise and aerobic dance can be performed in a water environment.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Muscle force development is influenced by both central (pre-motor end plate) and peripheral (post-motor end plate) components. Conflicting results are available concerning gender-related differences in the central component. This study compared males and females with regard to the following electro-mechanical response variables: total reaction time, pre-motor time, electro-mechanical delay, and the rate of force development during a maximal voluntary isometric contraction (MVC) of the elbow flexors. Forty-six males and 40 females performed MVCs against a bar attached to a force transducer. Subjects were instructed to attempt to flex the elbow with maximal force as rapidly as possible after perceiving a visual stimulus. Surface electromyographic activity was recorded from the biceps brachii and was sampled simultaneously with the force transducer data at 2 kHz and stored digitally. For data analyses the subjects were separated into four groups based on the force generated during the MVC: weak females, weak males, strong females, and strong males. Neither total reaction time nor pre-motor time was significantly different across groups. The electro-mechanical delay for both male groups was significantly shorter than for both female groups. Electro-mechanical delay was weakly, but significantly, correlated with rate of force development and maximum force. During a single MVC the times required to attain 25, 50, 75, and 100% MVC were similar in all groups. The results suggest that at least part of the gender difference in maximum strength may be due to differences in electro-mechanical response times.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The Kinetic Communicator (KINCOM), a microcomputer controlled, hydraulically driven device for the test, measurement, and rehabilitation of human joint function, was tested for the reliability and validity of its operating systems. Testing focused on the three primary functions of the KINCOM: lever arm position, lever arm velocity, and force measuring systems. Measurements of the functions were made via external devices and were compared to measurements simultaneously made by the KINCOM system. Tests were performed for both static and dynamic operation of the unit. Force measurements averaged a difference of 3.2% or less, lever arm speed was within 1.5% of the target speed in all cases, and no difference was found in position measurement. These discrepancies were felt to be due to calibration error and were not considered an indication of inaccuracy in the KINCOM system.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Interior loading strategies to modify the location and size of the effective hitting area of aluminum softball bats were identified. The effects of these strategies on theoretically derived and empirically determined relevant mechanical parameters were compared. Loading strategies consisted of adding 315 g to the interior of three similar (790 g) aluminum softball bats: 1) at the center of mass of the original bat (bat C); 2) at the ends of the bat and distributed so that the center of mass was unchanged, (bat A); and 3) at the ends of the bat and distributed so that the moment of inertia about the swing axis (I1) was the same as that of bat C (bat B).The following parameters were derived theoretically by considering the bat as a physical pendulum and empirically by observing the impact reaction impulse on the axis of suspension: 1) moment of inertia about the suspension axis (I0); 2) moment of inertia about the swing axis; 3) distance from the suspension axis to the center of percussion; and 4) the slope of the impact reaction impulse (&OV0440;1) relative to the impact impulse (&OV0440;) as a function of impact location. These values for each bat were compared. Both empirical and theoretically derived data indicated that: 1) the center of percussion of bat B was farther away from the axis than bats A and C; 2) the moment of inertia about the swing axis of bat A was much greater than that of bats B and C; and 3) the slope of the impact reaction regression line as a function of impact location for bat B was significantly less than that of the other bats. Thus, the effective hitting area of bat B was moved toward the barrel end of the bat and enlarged without a substantial increase in the moment of inertia about the swing axis.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID