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PubMed1998

Resistance training and energy balance.

In this brief review we examine the effects of resistance training on energy expenditure. The components of daily energy expenditure are described, and methods of measuring daily energy expenditure are discussed. Cross-sectional and exercise intervention studies are examined with respect to their effects on resting metabolic rate, physical activity energy expenditure, postexercise oxygen consumption, and substrate oxidation in younger and older individuals. Evidence is presented to suggest that although resistance training may elevate resting metabolic rate, it does not substantially enhance daily energy expenditure in free-living individuals. Several studies indicate that intense resistance exercise increases postexercise oxygen consumption and shifts substrate oxidation toward a greater reliance on fat oxidation. Preliminary evidence suggests that although resistance training increases muscular strength and endurance, its effects on energy balance and regulation of body weight appear to be primarily mediated by its effects on body composition (e.g., increasing fat-free mass) rather than by the direct energy costs of the resistance exercise.

Basal Metabolism↗
PubMed1994

Metabolic and ventilatory responses to anemic hypoxia in conscious rats.

We investigated the metabolic and ventilatory effects of anemia, which is characterized by a decrease in blood O2 content with no changes in arterial PO2 (PaO2). Anemia was obtained in conscious chronically instrumented adult male rats by substituting blood with equal volumes of Ringer lactate solution via the tail artery. Three hours later, we measured resting O2 consumption (VO2) by an open flow method and ventilation (VE) by the barometric method. Hemodilution to 80-90, 70-80, or 60-70% of the starting hematocrit and hemoglobin values had no major effects on VO2, VE, or mean arterial blood pressure (MAP). A 50-60% hemodilution reduced VO2 and MAP, with a modest increase in VE; the rats were hypocapnic, with normal PaO2. Infusion of vasopressin in a dosage sufficient to increase MAP to the basal value resulted in a reduction in VE, a further drop in VO2, and a return to normocapnia. Three days after hemodilution, hematocrit and hemoglobin were still low but ventilatory and metabolic parameters were normal. In conclusion, in this rat model of anemic hypoxia, 1) hypometabolism occurred without a drop in PaO2, implying that its manifestation does not require activation of the carotid body, and 2) the transient hypocapnia resulted from the VE stimulating effects of the hypotension.

Anemia↗
PubMed1991

Cyclic fluctuations in human serum lipid and apolipoprotein levels during the normal menstrual cycle: comparison with changes occurring during oral contraceptive therapy.

The influence of menstrual cycle phases and hormonal contraception on serum lipid and apolipoprotein (apo) levels was investigated in a group of normally menstruating young women. The study period covered a normal menstrual cycle (pretherapy), the fourth cycle of treatment with a triphasic oral contraceptive (OC) preparation, and the cycle immediately following interruption of therapy (cycle 5, posttherapy). Cycle phases were defined on the basis of serum hormone levels and basal body temperature determinations. Significant differences in cholesterol (free and esterified) levels were observed during the menstrual phase of both the normal menstrual cycle (lower) and the OC cycle (higher), when compared with the other phases. Triglycerides, which were higher under OCs, fluctuated similarly throughout the two cycles, but phase differences did not reach statistical significance. Apo AI and apo B were both higher under OCs, and apo B followed a trend similar to cholesterol during the two cycles. During the first month after discontinuation of OCs, cholesterol levels returned progressively to baseline values, while triglycerides were only partially decreased. We conclude that cyclic fluctuations in lipid levels do occur under the influence of both endogenous and exogenous sex hormones.

Adult↗
PubMed2000

Fusion of low-fusing porcelain to Ti-75 alloy: an experimental study.

OBJECTIVE: To study the stomatological feasibility of low-fusing porcelain fused to Ti-75 alloy. METHODS: Electroprobemicroanalysis (EPMA) and shear test were used to observe interface state and bonding strength of porcelaintitanium. RESULTS: Shear bond strengths of low-fusing porcelain with Ti-75 alloy and conventional porcelain each fused to metal (NC-VMK68) were 47.38 +/- 7.95 MPa and 48.50 +/- 7.60 MPa, respectively. There was no significant difference between the shear bonding strength of low-fusing porcelain with Ti-75 and that of conventional porcelain fused to metal (PFM) (P > 0.05). EPMA showed that Ti-75 alloy and low-fusing porcelain bound tightly, had no fissure, and that low-fusing porcelain had good infiltration to Ti-75. It was shown that Ti spread from Ti-75 basal body into porcelain, and elements such as Si-Sn spread from porcelain to Ti-75. CONCLUSION: Ti-75 alloy can be used stomatologically, as a porcelain alloy.

Biocompatible Materials↗
PubMed2006

Temperature dependence of O2 consumption; opposite effects of leptin and etomoxir on respiratory quotient in mice.

OBJECTIVES: The aims were to compare the temperature dependence of the metabolic rate in young ob/ob mice with that in mature ob/ob and db/db mice and to examine the effect on the metabolic substrate preference of leptin and etomoxir in ob/ob, C57BL/6J (wild-type), and db/db mice. RESEARCH METHODS AND PROCEDURES: In vivo oxygen consumption and carbon dioxide production were continuously measured by indirect calorimetry, and body temperature and total locomotor activity were measured by an implanted transponder. Leptin, etomoxir, or vehicle was administered intraperitoneally. RESULTS: The temperature dependence of the metabolic rate of mature ob/ob and db/db mice were similar to that in wild-type mice. In young 6-week-old ob/ob mice, the metabolic rate was almost doubled at 15 degrees C. Leptin (2 x 3 mg/kg) decreased the respiratory quotient (RQ) and carbon dioxide production but did not alter oxygen consumption, body temperature, or locomotor activity in ob/ob and C57BL/6J mice and had no effect in the db/db mice. Etomoxir (2 x 30 mg/kg) enhanced RQ and decreased oxygen consumption, carbon dioxide production, and body temperature in ob/ob, C57BL/6J, and db/db mice. Total locomotor activity was reduced in ob/ob and C57BL/6J mice. DISCUSSION: In young ob/ob mice, the temperature sensitivity was enhanced compared with mature mice. Leptin and etomoxir had opposite effects on metabolic substrate preference. Leptin and lowered environmental temperature increased the relative fat oxidation as indicated by decreased RQ, possibly through activation of the sympathetic nervous system.

Animals↗
PubMed2001

Effect of varying burn sizes and ambient temperature on the hypermetabolic rate in thermally injured rats.

BACKGROUND: Small animals with scald covering 50% of their total body surface area (TBSA) have been used to study the hypermetabolic burn response. In the 50% TBSA burn rat model, the area of normal skin that is available for animal instrumentation is restricted and the mortality rate has been high. The purpose of this study was to determine whether a smaller burn size can induce a similar hypermetabolic response with mortality rates lower than those of the 50% TBSA model. METHODS: Rats were randomly divided into four groups to receive a 0% (sham nonburned), 30%, 40%, or 50% TBSA third-degree scald burn. The hypermetabolic response was determined by measuring changes in body weight and oxygen consumption at ambient temperatures of 21, 26, and 31 degrees C for each burn size. Weight measurements were made daily while oxygen consumption was measured 7, 11, and 14 days after thermal injury. RESULTS: All thermally injured rats lost body weight; however, there were no significant differences between the 30, 40, and 50% TBSA burn groups. Burn induced a hypermetabolic response as indicated by an increase in oxygen consumption from 130 to 200% that of sham nonburned rats. No significant difference in oxygen consumption could be shown over the study period between the three burn sizes at different ambient temperatures. Mortality was 0% in the sham and 30% group, 10% for the 40% group, and 50% for the 50% TBSA burn group. CONCLUSIONS: From our study we conclude that a burn size covering 30% of the TBSA induces the same hypermetabolic response as a 50% TBSA burn.

Animals↗
PubMed1990

Heat production in isolated heart myocytes: differences among species.

A new calorimetry method has been developed to measure heat production from heart cell suspensions under continuous perfusion. The method is technically independent of the temperature at which the measurements are made, allows full control of the perfusion media, and is suitable for various biological preparations such as cells from diverse tissues, membrane vesicles, or skinned cells. The resting heat rate (Hr) measured at 18.5 degrees C in three different species (19.2 +/- 0.43, 12.8 +/- 0.56, and 9.4 +/- 0.52 mW/g dry wt for rat, guinea pig, and rabbit ventricular myocytes, respectively) agrees with that obtained with other methodologies such as oxygen consumption, thermopiles, and whole heart calorimetry. The Hr measurements showed an excellent correlation with the percentage of rod-shaped cells, indicating that rounded cells are metabolically inactive. Although the time course of the effect of increasing extracellular [K] was dependent on the species, the new steady level of Hr observed under higher extracellular [K] was significantly higher in all three species (+8.3 +/- 1.2, +9.5 +/- 4.0, and +9.3 +/- 2.7 mW/g dry wt for rat, guinea pig, and rabbit ventricular cells, respectively). This indicates that the commonly used "arrested-heart" preparation (with high extracellular [K]) for evaluation of basal metabolism most probably overestimates the real resting values. The present results also show that the wide range of resting metabolism reported in whole tissue is not due to cellular heterogeneity nor to myocyte interaction and supports the idea of an inverse relationship between resting metabolism and body weight or animal size across species.

Animals↗
PubMed2001

Corticosterone responses in 5-HT1B receptor knockout mice to stress or 5-HT1A receptor activation are normal.

RATIONALE: Previous research found no adaptations in presynaptic 5-HT1A receptors in mice lacking 5-HT1B receptors (5-HT1B KO). Stress and 5-HT1A receptor agonists induce corticosterone release in mice via hypothalamus-pituitary-adrenal (HPA) axis activation. 5-HT1B KO mice are hyperreactive to mild stressors and this might be reflected in altered postsynaptic 5-HT1A receptor sensitivity. OBJECTIVES: Our aim was to determine whether the activity of the HPA axis was increased in 5-HT1B KO mice in response to mild stress and pharmacological activation of 5-HT1A receptors as an indication of putative adaptive changes in postsynaptic 5-HT1A receptor function. METHODS: The effect of mild stress [i.e., the stress-induced hyperthermia (SIH) paradigm], induced by rectal temperature measurement, was determined on temperature and corticosterone over time (0, 5, 10, 20, 30, 60, and 90 min) in 5-HT1B KO and wildtype mice. In addition, corticosterone was measured 60 min after 5-HT1A receptor activation by flesinoxan (0, 0.03, 0.1, 0.3, 1, and 3 mg/kg s.c.). Blood was collected and plasma corticosterone levels were determined by radioimmunoassay. RESULTS: Both genotypes showed comparable time-dependent SIH responses, whereas basal temperature was higher in 5-HT1B KO mice. The effect of SIH on temperature was mirrored by mild increases in plasma corticosterone. Activation of 5-HT1A receptors caused a strong dose-dependent release of corticosterone in both genotypes. Neither response observed showed differences between both genotypes. CONCLUSIONS: Although 5-HT1B KO mice are hyperreactive to mild stress, this reactivity is not reflected by stronger corticosterone responses in the SIH paradigm. The lack of shift in dose-response curves for flesinoxan suggests that postsynaptic 5-HT1A receptor function is unaffected in 5-HT1B KO mice.

Animals↗
PubMed1999

Reduced resting metabolic rate in athletes with menstrual disorders.

PURPOSE: This study investigated metabolic and nutritional determinants in association with menstrual disorders in athletes. Athletes with normal menstrual function (AN; N = 21) and athletes with menstrual disorders (AD: N = 12) participated in this study. METHODS: The quality of the menstrual cycle was judged according to salivary progesterone concentrations. Resting metabolic rate (RMR) and diet-induced thermogenesis (DIT) were measured by indirect calorimetry. Body composition, energy intake and restrained eating scores were obtained. RESULTS: When adjusted for body composition by ANCOVA, RMR was significantly (approximately 460 kJ, P < 0.02) lower in athletes with menstrual disorders than in athletes without menstrual disorders. The DIT and the daily energy intake of the groups did not differ. Athletes with menstrual disturbances scored significantly higher on the Restraint Eating Scale (TFEQ). Thyroid hormones (fT3 and fT4), analyzed by a competitive chemiluminescent immunoassay, were in the normal range and not different between groups. CONCLUSIONS: The results provide evidence that restrained eating and low RMR are associated with menstrual cycle disturbances in athletes.

Adult↗
PubMed2004

Physiological and hematological responses to cold exposure in young subjects.

BACKGROUND: In this study we have investigated the effect of cold exposure on young healthy subjects, with particular emphasis on the hematological system. STUDY DESIGN: The lightly clothed subjects were seated in a thermally controlled climatic chamber for three hours. METHODS: One group (control) was exposed to three hours at 28 degrees C, while the other group was first exposed to one hour at 28 degrees C, and then two hours of decreasing temperature, ending at 6 degrees C. Mean body temperature decreased, blood pressure increased, and metabolism increased by 60% in the cold exposure group compared to the control group. Blood samples were taken through an arterial catheter every hour during the exposure, one hour before and 1.5, 3 and 25 hours after the exposure. RESULTS: Red blood cell counts increased, due to hemo-concentration. In the cold neutrophil counts did not increase during the day, but were stable at a lower level compared to the controls. CONCLUSIONS: It is suggested that the cold induced decrease in neutrophil count is caused by an activation and increased adhesion of the neutrophils to the endothelial wall. This finding is supported by the cold exposure-induced increases in IL-8 and Thromboxane B2 in LPS-stimulated blood, and an increase in the plasma concentration of P-selectin.

Adult↗
PubMed2005

Contribution of different mechanisms to compensation for energy restriction in the mouse.

OBJECTIVE: Restriction of energy intake produces weight loss, but the rate of loss is seldom sustained. This is presumed to be a consequence of compensatory reductions in energy expenditure, although the exact contributions of different components to the energy budget remain uncertain. We examined the compensatory responses of mice to a 20% dietary restriction. RESEARCH METHODS AND PROCEDURES: We measured body mass, body fatness, body temperature, and the components of daily energy expenditure for 50 MF1 mice. Forty mice were then placed on a restricted diet at 80% of their ad libitum intake for 50 days. The remaining 10 mice continued to feed ad libitum. Ten days before the end of the restriction period, the same measurements were taken. RESULTS: There were no significant differences between the control and restricted groups in any parameters before restriction. During the restriction period, body mass increased in both the control and restricted groups, but at a slower rate in the restricted mice. The control group increased in both fat and fat free mass; however, although the restricted group increased fat to the same extent as the controls, fat free mass increased to a lesser extent. The contributions of the different components of the expended energy to compensate for the reduced energy intake were energy deposition, 2.2%; resting metabolic rate, 22.3%; and activity, 75.5%. DISCUSSION: Mice were able to compensate almost completely for the restricted energy intake that was achieved by altering the amount of energy required for each component of the energy budget except digestive efficiency.

Analysis of Variance↗
PubMed1986

Sexual behavior and steroid levels among gynecologically mature premenopausal women.

Twenty-seven gynecologically mature young women who participated in a 14-week study prospectively recorded daily sexual behavior and basal body temperature data. In addition, they supplied plasma three times during the last cycle of participation. Plasma was analyzed for estradiol (E2), testosterone (T), and progesterone (P) by radioimmunoassay. The levels of circulating sex steroid hormones during the luteal phase were examined in relation to measures of menstrual cycle length, sexual frequency, and coital total. The results indicated the following: (1) women who had weekly sex with men had higher levels of estrogen than women who did not; (2) total amount of coital behavior was not related to any of the hormones assayed; (3) neither T nor P were distinguished by the consistency of sexual behavior or by coital total; and (4) women with aberrant-length cycles tended to have lower levels of E2. Thus, E2 consistently showed relationships to sexual behavior and cycle length, whereas P and T did not.

Adolescent↗
PubMed1998

Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning.

This was a multicentred, prospective study of pregnancies among women using natural family planning. The women maintained natural family planning charts of the conception cycle, recording acts of intercourse and signs of ovulation (cervical mucus changes, including peak day and basal body temperature). Charts were used to assess the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle. The sex ratio (males per 100 females) for 947 singleton births was 101.5, not significantly different from the expected value of 105. The sex ratio did not vary consistently or significantly with the estimated timing of insemination relative to the day of ovulation, with the estimated length of the follicular phase or with the planned or unplanned status of the pregnancy. Although these findings may be affected by imprecision of the data, the study suggests that manipulation of the timing of insemination during the cycle cannot be used to affect the sex of offspring.

Family Planning Services↗
PubMed1996

Determinants of weight loss following ileogastrostomy.

To examine the factors associated with weight loss following ileogastrostomy, (i) energy expenditure, (ii) body composition and (iii) urinary and fecal energy losses were examined in 11 morbidly obese subjects (36 +/- 3 y, 43.7 +/- 0.9 kg/m2 BMI, 47.0 +/- 1.3% body fat (BF) (mean +/- SEM) prior to and after this surgical procedure. Respiratory gas exchange analysis was used to measure changes in basal energy expenditure (BEE) and thermic effect of food (TEF). Total energy expenditure (TEE) was determined by doubly labeled water (DLW) method over 14 d during 6-8 weeks after surgery. Body composition was assessed using isotope dilution space (IDS) method. Illegastrostomy did not significantly influence BEE levels but TEF declined following surgery (p = 0.001). There was a significant decline (p < 0.0001) in fat-free mass (FFM) and fat mass (FM). Weight loss was closely associated with TEE (r = 0.719, p = 0.019, n = 10), and fecal energy content (r = 0.808, p = 0.052, n = 6) but not with urinary energy loss (r = 0.011, p = 0.983, n = 6). The results indicate that ileogastrostomy blunts TEF levels and both FFM and FM declined following surgery. Total energy expenditure and fecal energy losses appear to be important determinants in the extent of weight loss following ileogastrostomy.

Adult↗
PubMed2003

Cyclicity of breast tenderness and night-time vasomotor symptoms in mid-life women: information collected using the Daily Perimenopause Diary.

OBJECTIVE: The purpose was to explore cyclicity of breast tenderness and vasomotor symptoms in menstruating mid-life women using the Daily Perimenopause Diary. METHODS: Untreated mid-life women from a convenience sample completed the Daily Perimenopause Diary for clinical (n = 14) or research (n = 10) assessments. Breast tenderness, sleep disturbance and day and night vasomotor intensity were rated on a 0-4 scale with vasomotor number as a count. Daily oral temperature data were analyzed using the Quantitative Basal Temperature algorithm to assess ovulation and estimate luteal phase length. Analysis of variance tested cyclicity using the mean of three 3-day windows (during flow, at mid-cycle and premenstrually). RESULTS: Ninety-eight complete flow-to-flow diaries (from 24 women, mean age 47 years, cycle length 27 +/- 6.4 (standard deviation) days) were available, with quantitative temperature data for 60 cycles in 16 women. Of assessed cycles, 90% were ovulatory; 25% had luteal phases < 10 days. Breast tenderness was maximal in the premenstrual window overall (p < 0.0001) and in the ovulatory subset. Night sweats were maximal premenstrually (p = 0.0035) except in anovulatory cycles. Daytime flushes were not cyclic (p = 0.1333) except in ovulatory cycles (p = 0.031). CONCLUSION: Daily Perimenopause Diaries from mid-life women show premenstrual increases in breast tenderness and night sweats.

Adult↗
PubMed2001

Oxygen consumption and resting energy expenditure during phototherapy in full term and preterm newborn infants.

OBJECTIVES: To determine the effect of phototherapy on the oxygen consumption and resting energy expenditure of term and preterm newborn infants. METHODS: A total of 202 infants (gestation 30-42 weeks; body weight 1270-4100 g) requiring phototherapy for the treatment of neonatal hyperbilirubinaemia were enrolled in a randomised crossover study. In random sequence, the oxygen consumption and resting energy expenditure were measured twice in each infant by indirect calorimetry, once at the end of six hours of continuous phototherapy and once after a control period of at least six hours without phototherapy. Anterior abdominal wall temperature was servocontrolled at 36.5 degrees C throughout the study. RESULTS: At the end of six hours of continuous phototherapy, oxygen consumption (mean (SD): 6.21 (1.35) v 6.26 (1.51) ml/kg, p = 0.555) and resting energy expenditure (178.11 (37.62) v 180.37 (43.14) kJ/kg/24 h, p = 0.382) did not differ significantly from those measured after the control period. There were also no significant differences in heart rate, respiratory rate, or rectal temperature. Subgroup analysis of those of gestation < 37 weeks or < 34 weeks also showed no effect of phototherapy on either oxygen consumption or resting energy expenditure. CONCLUSION: Phototherapy has no effect on the metabolic rate of thermally stable term or preterm infants.

Basal Metabolism↗
PubMed2003

Energy requirements of non-ambulatory, tube-fed adult patients with cerebral palsy and chronic hypothermia.

OBJECTIVES: We investigated the energy requirements of non-ambulatory patients with severe neurodevelopmental disabilities and chronic hypothermia. METHODS: Six adult patients with a permanent ostomy for tube feeding were studied. Otic temperature was taken before the indirect calorimetry measurements. Prescribed tube-feeding intake and nutrient prescription changes were evaluated for 4 y for each patient. Monthly body weights and periodic anthropometric body fat assessments were measured for assessment of the need for weight gain, loss, or maintenance. The prescribed caloric intake was compared with the measured energy expenditure when normothermic, the Harris-Benedict equations, and the Arlington Developmental Center equation for non-ambulatory adult patients with severe neurodevelopmental disabilities (estimated resting energy expenditure [kcal/d] = [22.3 x fat-free mass [kg]] - [9.4 x age [y]] + 557). RESULTS: Mean energy expenditure was 783 +/- 81 kcal/d or 29.0 +/- 10.9 kcal. kg(-1)d(-1) when normothermic versus 606 +/- 11 kcal/d or 19.5 +/- 8.5 kcal. kg(-1)d(-1) (P < 0.05) when hypothermic (36.9 degrees C +/- 0.4 versus 35.5 degrees C +/- 0.4; P < 0.02), respectively. Prescribed caloric intakes to achieve weight gain, maintenance and loss were 138 +/- 13%, 105 +/- 15%, and 74 +/- 11% of the measured energy expenditure when normothermic (P < 0.001); 107 +/- 19%, 86 +/- 18%, and 56 +/- 3% of the Harris-Benedict equations (P < 0.02); or 130 +/- 23%, 100 +/- 19%, and 75 +/- 11% of the Arlington Developmental Center equation (P < 0.02). CONCLUSIONS: Measured energy expenditure when the patient is normothermic significantly overestimated actual caloric needs. The energy intake necessary to achieve desired weight changes are restrictive when compared with the basal energy expenditure, Arlington Developmental Center equation, or measured energy expenditure when normothermic.

Adult↗
PubMed1996

Effect of CO2 on the metabolic and ventilatory responses to ambient temperature in conscious adult and newborn rats.

1. In newborn and adult rats, hypoxia decreases metabolic rate, especially at low ambient temperatures (Ta). We examined whether a similar effect can occur during hypercapnia. 2. We measured metabolism (oxygen consumption, Vo2, open flow-through method), and expiratory ventilation (VE; barometric method (adults), airflow plethysmograph (newborns)) in air and 2% or 5% CO2 in normoxia. 3. In adults, Vo2 was higher at Ta = 10 degrees C than 25 degrees C. At each Ta, CO2 breathing did not change Vo2, but increased VE, less at 10 degrees C (up to +100%) than at 25 degrees C (+161%). Blood pressure was maintained at both values of Ta and CO2, while pulse rate and body temperature were decreased in 5% CO2 at 10 degrees C. 4. In newborns, the metabolic response to lowering Ta (from 40 to 20 degrees C) much depended on behavioural responses, being larger in groups of two or four pups than in individual animals. In no case did CO2 influence the response. VE increased during 5% CO2 exposure, more so at Ta = 33 percent C (+69%) than at 25 degrees C (+49%). 5. In both adults and newborns, hypoxia (10% O2) always decreased metabolic rate. 6. We conclude that hypercapnia has no appreciable effects on metabolic rate in rats (both newborns and adults) even at low Ta, a result quite different from the hypometabolic response to hypoxia.

Aging↗