Differences In Resting Metabolic Rate Research Articles

Pace-of-life syndrome: linking personality, metabolism and colour ornamentation in male guppies

Within populations, there commonly exists consistent among-individual differences in behaviour. As a potential mechanism maintaining this variation, the pace-of-life-syndrome (POLS) hypothesis posits that consistent differences in the behaviour of individuals (i.e. ‘personality’) are intercorrelated and have coevolved with consistent individual differences in metabolism and life-history traits. Here, using adult male guppies, Poecilia reticulata , we tested under laboratory conditions (1) whether behavioural and metabolic traits vary consistently among individuals over time (≤7 days) and (2) the POLS prediction that repeatable behavioural traits should be intercorrelated with each other and with repeatable metabolic rate at the among-individual level. Furthermore, based on indicator models of sexual selection, we expected that sexually selected male colour ornamentation would predict individual personality and metabolic rate. We repeatedly assayed three behavioural traits (sociability, boldness, exploration) and three metabolic traits (resting metabolic rate, maximal metabolic rate, aerobic scope) in a set of males that varied in body size and colour ornamentation. All behavioural trait measures were repeatable, consistent with individual personality. Of the three metabolic traits, only resting metabolic rate (RMR) was repeatable. Behavioural trait measures were significantly intercorrelated and thus integrated in a behavioural syndrome. More ‘proactive’ males were bolder, more exploratory and more sociable than ‘reactive’ ones. However, contrary to the POLS hypothesis, RMR was not significantly correlated with any of the behavioural trait measures, suggesting that consistent individual differences in RMR do not drive or support differences in personality, or vice versa. Male colour ornamentation did not covary with behaviour or RMR and thus does not appear to be a reliable predictor of either behavioural or metabolic phenotypes. We therefore did not find any compelling support for the POLS hypothesis, suggesting that individual differences in metabolism do not underlie the evolution and maintenance of among-individual behavioural variation in our study population. • We tested for behaviour–metabolism covariation in guppies (pace-of-life syndrome, POLS). • Behaviour and resting metabolic rate (RMR) differed consistently among males. • Behavioural differences between males, however, did not covary with their RMR. • Male colour ornamentation did not predict either their personality or metabolism. • Overall, our results do not support the central prediction of the POLS hypothesis.

Appetitive and Metabolic Responses to an Exercise versus Dietary Intervention in Adults with Obesity.

Dietary restriction (DIET) and aerobic exercise (AEX) interventions may impact energy balance differently. Our aim was to describe the effects of weight loss interventions via DIET or AEX on measures of energy balance. Adults with overweight or obesity were randomized to 12 weeks of DIET or AEX with similar calorie deficit goals. A study day was conducted before and after the intervention to assess subjective and hormonal (ghrelin, peptide-YY, glucagon-like peptide-1) appetite responses to a control meal, ad libitum energy intake (EI) at a single meal, and over three days of free-living conditions and eating behavior traits. Resting metabolic rate (RMR) was measured with indirect calorimetry and adjusted for body composition measured by dual X-ray absorptiometry. Non-exercise activity was measured using accelerometers. Forty-four individuals were included (age: 37 ± 9 years, body mass index: 30.6 ± 3.1 kg/m2). Both interventions resulted in weight and fat mass loss. The DIET group lost fat-free mass, although differences between groups were not significant (DIET: -1.2 ± 1.7 kg, p<0.001; AEX: 0.4 ± 1.5 kg, p=0.186; p=0.095 interaction). There were no differences in RMR after body composition adjustment. Both interventions were associated with an increase in dietary restraint (DIET: 4.9 ± 1.2, AEX: 2.8 ± 0.7; p<0.001 in both groups). Hunger decreased with DIET (-1.4 ± 0.5, p=0.003), and disinhibition decreased with AEX (-1.5 ± 0.5, p<0.001), although these changes were not different between groups (i.e., no group × time interaction). No other differences in appetite, EI, or non-exercise physical activity were observed within or between groups. AEX did not result in compensatory alterations in appetite, ad libitum EI, or physical activity, despite assumed increased energy expenditure. Modest evidence also suggested that disinhibition and hunger may be differentially impacted by weight loss modality.

Short-term Induced Low Energy Availability On Metabolic Rate And Mood States In Male Runners

PURPOSE: To investigate the effect of an acute (4-day) period of low energy availability (EA) on resting metabolic rate (RMR) and mood states in trained male endurance runners. METHODS: 12 male endurance runners (mean (standard deviation); age: 25.8 (3.7) yrs; body mass index: 20.9 (2.0) kg/m2; fat free mass (FFM): 52.8 (5.5) kg) completed three 4-day conditions of controlled EA (15, 30, and 45 kcal/kg/FFM), in a randomised and crossover manner. In each condition, participants ran on a treadmill at 65% of VO2max until they achieved a daily exercise energy expenditure of 15 kcal/kg/FFM. Energy intake was adjusted to achieve the desired level of EA in each condition. RMR and mood states were measured after a 10-12 hour fast on the morning of Day 1 (pre) and Day 5 (post) of each condition. RMR was measured by indirect calorimetry (ventilated hood) and mood states were measured by the Brunel Mood Scale (BRUMS), that consists of six dimensions - fatigue, depression, vigor, anger, tension, and confusion. A two-way repeated measures ANOVA (condition × time) was used to examine differences in RMR. A two-way repeated measures MANOVA (condition × time) was used to examine the differences in BRUMS dimensions. RESULTS: For RMR, no significant interaction was found between condition and time (p = 0.329). For mood states, a significant interaction was found in fatigue scores (p = 0.035). Participants felt greater fatigue (tiredness) in the post measure in the 15 kcal/kg/ FFM condition, as compared to the other conditions (30 and 45 kcal/kg/ FFM). A main effect was found in vigor scores over time (p = 0.036). Participants generally felt more vigor (energy) at the pre than post measure irrespective of EA conditions. CONCLUSIONS: These findings indicate that RMR in male runners was not influenced by short-term LEA induced by restricted energy intake and exercise energy expenditure, suggesting that metabolism may not be affected by acute periods of LEA. Hence, RMR may not be a sensitive enough tool to detect the early stages of LEA. Short-term LEA did affect mood states (fatigue and vigor) in male runners. This suggests that LEA should be adjusted as soon as it is detected to prevent further impact on psychological state. It also suggests that a state of increased fatigue, and/or decreased vigor, could be an indicator or symptom of LEA, in male runners.

Resting metabolic rate in adults with facioscapulohumeral muscular dystrophy.

This study aimed to determine whether resting metabolic rate (RMR) is altered in adults with facioscapulohumeral muscular dystrophy (FSHD). Eleven people with FSHD (51± 12yrs, 2 females) and 11 controls (48± 14 yrs, 2 females) completed 1 visit, including 30-minutes of indirect calorimetry and dual-energy X-ray absorptiometry (DXA) scanning. RMR was calculated from resting oxygen consumption/carbon dioxide production; regional/whole-body fat mass and lean mass were collected from the DXA scan. Absolute RMR was 15% lower in FSHD (p= 0.04); when normalized to regional/local lean mass, no differences in RMR were observed (p> 0.05). Absolute RMR was correlated with total lean mass for all participants combined (p< 0.01, r= 0.70, males only: p< 0.01, r= 0.81) and when analyzed separately (FSHD males: p= 0.001, r= 0.92 and control males: p= 0.004, r= 0.85). Whole-body lean mass was 16% lower in FSHD and leg, arm and appendicular lean mass were lower in FSHD (p< 0.05 for all), though trunk lean mass was not (p= 0.15). Whole-body fat mass was 45% higher in FSHD, with greater leg fat mass (p= 0.01), but not trunk or arm fat mass (p> 0.05 for both). When RMR was expressed relative to lean body mass, no differences in RMR were found, indicating that the lower levels of lean mass observed in FSHD patients likely contribute to the lower absolute RMR values. Novelty: RMR is lower among people with FSHD, as compared with controls. The reduced RMR among people with FSHD is due to disease-related loss in muscle mass and likely related to lower physical activity and/or exercise levels.

Factors Associated With Energy Expenditure and Energy Balance in Acute Sport-Related Concussion.

Sport-related concussion (SRC) is characterized by a pathologic neurometabolic cascade that results in an increased intracranial energy demand and a decreased energy supply. Little is known about the whole-body energy-related effects of SRC. To examine factors associated with whole-body resting metabolic rate (RMR), total energy expenditure (TEE), energy consumption (EC), and energy balance (EBal) in student-athletes acutely after SRC and healthy matched control individuals. Case-control study. University research laboratory. Student-athletes diagnosed with SRC (n = 28, 50% female, age = 18.4 ± 1.8 years, body mass index [BMI] = 24.1 ± 4.1 kg/m2) assessed ≤72 hours postinjury and a matched control group (n = 28, 50% female, age = 19.4 ± 2.9 years, BMI = 24.7 ± 4.78 kg/m2). Resting metabolic rate was measured via indirect calorimetry. Participants reported their physical activity and dietary intake for 3 days, which we used to estimate TEE and EC, respectively, and to calculate EBal (EC:TEE ratio). Resting metabolic rate, TEE, and EC were normalized to body mass. Group and group-by-sex comparisons were conducted for RMR·kg-1, TEE·kg-1, EC·kg-1, and EBal using independent t tests with the a priori α = .05. Associations of age, sex, concussion history, BMI, and symptom burden with RMR·kg-1 and EBal were explored with linear regression models. Total energy expenditure·kg-1 was lower (P < .01; mean difference ± SD = -5.31 ± 1.41 kcal·kg-1) and EBal was higher (P < .01; 0.28 ± 0.10) in SRC participants than in control participants. Both sexes with SRC had lower TEE·kg-1 than did the control participants (P values ≤ .04); females with SRC had higher EBal than controls (P = .01), but male groups did not differ. Higher RMR·kg-1 was associated with history of concussion (adjusted R2 = .10, β = 0.65). Younger age (β = -0.35), fewer concussions (β = -0.35), lower BMI (β = -0.32), greater symptom duration (β = 1.50), and lower symptom severity (β = -1.59) were associated with higher EBal (adjusted R2 = .54). Total energy expenditure·kg-1 and EBal appeared to be affected by acute SRC, despite no differences in RMR·kg-1. Sex, concussion history, BMI, and symptom burden were associated with acute energy-related outcomes.

Males Exceeding Females in Whole-Fish Polychlorinated Biphenyl Concentration Mainly Attributable to Higher Energy Expenditure Rate.

Males Exceeding Females in Whole-Fish Polychlorinated Biphenyl Concentration Mainly Attributable to Higher Energy Expenditure Rate.

Impact of the Method Used to Select Gas Exchange Data for Estimating the Resting Metabolic Rate, as Supplied by Breath-by-Breath Metabolic Carts.

The method used to select representative gas exchange data from large datasets influences the resting metabolic rate (RMR) returned. This study determines which of three methods yields the lowest RMR (as recommended for use in human energy balance studies), and in which method the greatest variance in RMR is explained by classical determinants of this variable. A total of 107 young and 74 middle-aged adults underwent a 30 min RMR examination using a breath-by-breath metabolic cart. Three gas exchange data selection methods were used: (i) steady state (SSt) for 3, 4, 5, or 10 min, (ii) a pre-defined time interval (TI), i.e., 6–10, 11–15, 16–20, 21–25, 26–30, 6–25, or 6–30 min, and (iii) “filtering”, setting thresholds depending on the mean RMR value obtained. In both cohorts, the RMRs yielded by the SSt and filtering methods were significantly lower (p < 0.021) than those yielded by the TI method. No differences in RMR were seen under the different conditions of the SSt method, or of the filtering method. No differences were seen between the methods in terms of the variance in RMR explained by its classical determinants. In conclusion, the SSt and filtering methods return the lowest RMRs and intra-measurement coefficients of variation when using breath-by-breath metabolic carts.

Sex Differences in Resting Metabolic Rate Among Athletes.

Jagim, AR, Camic, CL, Askow, A, Luedke, J, Erickson, J, Kerksick, CM, Jones, MT, and Oliver, JM. Sex differences in resting metabolic rate among athletes. J Strength Cond Res 33(11): 3008-3014, 2019-The purpose of this study was to compare differences in resting metabolic rate (RMR) between sexes in Division III National Collegiate Athletic Association (NCAA) collegiate athletes and to identify predictors of RMR. Sixty-eight male (M) (age: 20.1 ± 1.5 years; height: 181.8 ± 5.9 cm; body mass (BM): 93.7 ± 16.3 kg; and body fat%: 16.3 ± 8.6%) and 48 female (F) athletes (age: 19.4 ± 1.3 years; height: 166.5 ± 6.0 cm; BM: 63.4 ± 12.7 kg; and body fat%: 21.5 ± 6.3%) participated in a single day of testing, which included determination of RMR using indirect calorimetry and air displacement plethysmography to measure fat mass and fat-free mass (FFM). An independent-samples t-test was used to compare differences in body composition and RMR between sexes, and regression analysis was used to identify predictors of RMR. Men had a significantly higher absolute RMR (M: 2,481 ± 209 vs. F: 1,553 ± 193 kcals·d; p < 0.001), but when adjusted for BM (M: 25.6 ± 8.3 vs. F: 25.9 ± 2.5 kcals·kg BM per day; p = 0.82) and FFM (M: 31.1 ± 10.6 vs. F: 33.6 ± 3.8 kcals·kg FFM per day; p = 0.12), these differences became nonsignificant. Regression analysis indicated that BM in both men (β = 0.73) and women (β = 0.88) was the strongest predictor of RMR. The results of the current study indicate minimal differences in RMR between sexes among athletic populations when adjusted for BM and FFM. In the current group of athletes, BM seems to account for the largest variability in RMR.

Sex-Specific Among-Individual Covariation in Locomotor Activity and Resting Metabolic Rate in Drosophila melanogaster.

A key endeavor in evolutionary physiology is to identify sources of among- and within-individual variation in resting metabolic rate (RMR). Although males and females often differ in whole-organism RMR due to sexual size dimorphism, sex differences in RMR sometimes persist after conditioning on body mass, suggesting phenotypic differences between males and females in energy-expensive activities contributing to RMR. One potential difference is locomotor activity, yet its relationship with RMR is unclear and different energy budget models predict different associations. We quantified locomotor activity (walking) over 24 h and RMR (overnight) in 232 male and 245 female Drosophila melanogaster that were either mated or maintained as virgins between two sets of measurements. Accounting for body mass, sex, and reproductive status, RMR and activity were significantly and moderately repeatable (RMR: ; activity: ). RMR and activity were positively correlated among () but not within () individuals. Moreover, activity varied throughout the day and between the sexes. Partitioning our analysis by sex and activity by time of day revealed that all among-individual correlations were positive and significant in males but nonsignificant or even significantly negative in females. Such differences in the RMR-activity covariance suggest fundamental differences in how the sexes manage their energy budget.

Effects of different intensity interval exercise of 6 weeks on body composition of obese rats

To investigate the effects of different intensity intermittent exercise on the body function of obese rats, and to provide basis for the prevention and treatment of obesity. Eighty SD rats were randomly divided into normal diet group (n=20) and high-fat diet group (n=60). After adaptive feeding for 8 weeks, 8 normal diet rats and 32 high-fat obese rats were selected for follow-up experiments. The experimental rats were randomly divided into 5 groups (n=8): control diet-sedentary (CS),with ordinary feed and without any exercise; high diet-sedentary (HS), with high-fat feed feeding and without any exercise; high diet-continual exercise(HC), 60 min/day,5 days/week with 6 weeks; high diet-long time-low frequency interval exercise(HLL), 30 min/time,twice/day (intermittent 6 h), 5 days/week with 6 weeks; high diet-short time-high frequency interval exercise(HSH), 20 min/ time, 3 times/d (intermittent 3 h), 5 days/week with 6 weeks. The training intensity of rats in each exercise group was 25 m/min. After 6 weeks, rats in each groups were weighed, and resting metabolic rate(RMR), fasting blood glucose(FBG), triglyceride(TG) and other biochemical indexes were detected, and fat and muscle weight were measured. Before experiment, there were no significant differences in RMR, FBG and TG in each groups(P＞0.05).The body weight of HSH, HLL, HC and HS groups was higher than that of CS group (P＜0.05). After the experiment, RMR of the HSH,HLL and HC groups was significantly higher than that of HS and CS groups (P＜0.05), but without significant difference among the HSH,HLL and HC groups (P＞0.05).The body weight of HSH, HLL and HC groups was significantly lower than that of HS group (P＜0.05), but the three groups was not significant (P＞0.05); perirenal fat(PF), idymis fat(EF), perirenal fat/weight(PF/W) and epididymis fat/weight(EF/W) of HSH, HLL, HC group were significantly lower than those of HS group (P＜0.01), while there was no statistical difference among the three groups (P＞0.05). There was no significant difference in gastrocnemius(GM) and quadricep(QF) of each group (P＞0.05), gastrocnemius/weight(GM/W) and quadriceps/weight (QF/W) in HSH,HLL and HC groups were higher than those of HS group (P＜0.05),while there was no significant difference among HSH,HLL and HC groups (P＞0.05);FEB,TG of HSH,HLL,HC group were lower than those of CS and HS group (P＜0.05),but the difference with HS group was more significant (P＜0.01),there was no significant difference among training groups(P＞0.05). 6 weeks of intermittent exercise of different intensity had a good intervention effect on the body composition of obese rats, and high diet-short time-high frequency interval exercise (HSH) may be more effective.

Impact of Feeding on Resting Metabolic Rate and Gas Exchange in Critically Ill Patients.

Feeding is understood to alter gas exchange and resting metabolic rate (RMR) in critically ill patients, but there are limited data describing such changes. A large collection of RMR measurements and energy intake was assembled in mechanically ventilated and critically ill patients. The data were used to explore differences in RMR, respiratory quotient (RQ), and carbon dioxide production (V̇co2 ) related to feeding state. A total of 708 RMR measurements were available. No significant thermogenic effect of feeding could be appreciated. When controlled for body weight, the difference was 4.2% (1946±400kcal/d for unfed vs 2028±341kcal/d for fed patients; P=.299), and this small difference was fully eliminated when body temperature was also controlled for. RQ increased as carbohydrate and energy intake increased, but there was much variation in the relationship. Among 215 overfed patients, only 22 had RQ ≥1.0, and among 9 patients whose carbohydrate intake alone exceeded RMR, only 4 had an RQ ≥1.0. V̇co2 was influenced mainly by the volume of oxygen consumed and to a lesser degree by carbohydrate intake. No appreciable thermogenic effect of feeding occurs in continuously fed critically ill patients. This factor does not need to be considered in the assessment of resting energy needs. RQ is not a reliable indicator of overfeeding, and the ability of carbohydrate intake to alter V̇co2 is small, although not absent.

The Assessment of Total Energy Expenditure During a 14-Day In-Season Period of Professional Rugby League Players Using the Doubly Labelled Water Method.

Rugby League is a high-intensity collision sport competed over 80 min. Training loads are monitored to maximize recovery and assist in the design of nutritional strategies although no data are available on the total energy expenditure (TEE) of players. We therefore assessed resting metabolic rate (RMR) and TEE in six Super League players over 2 consecutive weeks in-season including one game per week. Fasted RMR was assessed followed by a baseline urine sample before oral administration of a bolus dose of hydrogen (deuterium 2H) and oxygen (18O) stable isotopes in the form of water (2H218O). Every 24 hr thereafter, players provided urine for analysis of TEE via DLW method. Individual training load was quantified using session rating of perceived exertion (sRPE) and data were analyzed using magnitude-based inferences. There were unclear differences in RMR between forwards and backs (7.7 ± 0.5 cf. 8.0 ± 0.3 MJ, respectively). Indirect calorimetry produced RMR values most likely lower than predictive equations (7.9 ± 0.4 cf. 9.2 ± 0.4 MJ, respectively). A most likely increase in TEE from Week 1 to 2 was observed (17.9 ± 2.1 cf. 24.2 ± 3.4 MJ) explained by a most likelyincrease in weekly sRPE (432 ± 19 cf. 555 ± 22 AU), respectively. The difference in TEE between forward and backs was unclear (21.6 ± 4.2 cf. 20.5 ± 4.9 MJ, respectively). We report greater TEE than previously reported in rugby that could be explained by the ability of DLW to account for all match and training-related activities that contributes to TEE.

Cross‐Validation of Recent and Longstanding Resting Metabolic Rate Prediction Equations

Resting metabolic rate (RMR) measurement is time consuming and requires specialized equipment. Prediction equations provide an easy method to estimate RMR; however, their accuracy likely varies across individuals. Understanding the factors that influence predicted RMR accuracy at the individual level will help to revise existing or develop new equations that are more accurate. The objective of the present study was to test the validity of established (Harris‐Benedict, WHO, Mifflin‐St. Jeor) and contemporary (3 meta equations of Sabounchi and colleagues, 1 equation of Nelson and colleagues, 1 by Wang and colleagues) RMR prediction equations in healthy adults.DesignPredicted RMR was tested for agreement with indirect calorimetry. Men and women (n=30) age 18–65y from Grand Forks, ND were recruited and included for analysis during Spring/Summer 2014. Participants were nonobese to obese, primarly Caucasian and a representive sample of a healthy, free‐living population. The main outcome measure was bias between measured (indirect calorimetry) and predicted RMR. The methods of Bland and Altman were employed to determine mean bias (predicted minus measured RMR, kcal/day) and limits of agreement between predicted and measured RMR. Repeated measures ANOVA was utilized to test for differences in RMR predicted from each equation versus the measured RMR. Mean bias was lowest for the Harris‐Benedict (4 ± (2 SD) 386 kcal/24 hrs) and WHO (25 ± 402 kcal/24 hrs) equations and these mean predicted RMR did not differ from measured. Mean RMR predictions from all other equations significantly differed from indirect calorimetry. The 2 SD limits of agreement were moderate or large for all equations tested ranging from 282 to 445 kcal/24 hrs. Prediction bias was positively associated with the magnitude of RMR and with FFM. In conclusion, the traditional Harris‐Benedict and WHO equations were the most accurate. However, even these equations did not perform well at the individual level. As FFM increased, the prediction equations further underestimated RMR.Support or Funding InformationSupport: USDA‐ARS 3062‐51000‐051‐00D

Longevity, calling effort, and metabolic rate in two populations of cricket

Intraspecific variation in a resting metabolic rate (RMR) is likely to be an important determinant of energetic-resource use and may influence the resources subsequently available for allocation to traits not directly associated with somatic maintenance. The influence of RMR on resource availability could be especially important for condition-dependent sexual traits, such as cricket calls, that are themselves energetically costly to produce. RMR may also be associated with longevity, either negatively because individuals with a high RMR burn resources faster and die young, or positively as individuals with high RMR are more able to accrue resources to fuel survival. Additionally, the associations between RMR and other characters may vary across populations if differential selection or drift shapes these traits. Here we tested for differences in RMR, body mass, calling effort, and longevity in two populations of cricket Gryllodes sigillatus and then evaluated the potential influence of RMR on calling and longevity. We find that RMR, calling effort, and longevity varied across populations, but mass did not. Controlling for population and mass, RMR was not significantly associated with calling effort, but was negatively associated with longevity. These findings suggest that male crickets that live fast die young.

European ancestry and resting metabolic rate in older African Americans

Resting metabolic rate (RMR) contributes 60-80% of total energy expenditure and is consistently lower in populations of African descent compared with populations of European populations. Determination of European ancestry (EA) through single nucleotide polymorphism (SNP) analysis would provide an initial step for identifying genetic associations that contribute to low RMR. We sought to evaluate the association between RMR and EA in African Americans. RMR was measured by indirect calorimetry in 141 African American men and women (aged 74.7±3.0 years) enrolled in a substudy of the Health, Aging and Body Composition Study. Ancestry informative markers were used to estimate individual percent EA. Multivariate regression was used to assess the association between RMR and EA after adjustments for soft tissue fat-free mass (STFFM), fat mass, age, study site, physical activity level and sex. Mean EA was 23.8±16% (range: 0.1-70.7%) and there were no differences by sex. Following adjustments, each percent EA was associated with a 1.6 kcal/day (95% Confidence interval: 0.42, 2.7 kcal/day) higher RMR (P=0.008). This equates to a 160 kcal/day lower RMR in a population of completely African ancestry, with one of completely European ancestry. Additional adjustment for trunk STFFM that partially accounts for high-metabolic rate organs did not affect this association. EA in African Americans is strongly associated with higher RMR. The data suggest that population differences in RMR may be due to genetic variants.

Toward quantifying the usage costs of human immunity: Altered metabolic rates and hormone levels during acute immune activation in men

There is a paucity of data on the energetic demands of human immune functions, despite the fact that both clinical medicine and evolutionary biology would benefit from further clarification of these costs. To better understand the energetic requirements of mounting a mild immune response, as well as some of the major hormonal changes underlying these metabolic changes, we examined changes in resting metabolic rate (RMR) and hormones during and after respiratory tract infection in young adult men. An epidemiologic passive detection design was used to recruit 25 nonfebrile subjects naturally infected with respiratory tract pathogens. Symptomology, percent body fat, RMR, salivary testosterone and cortisol, and other information were collected at a minimum of three time points during and after convalescence. Comparisons of the differences in RMR, testosterone, and cortisol between sampling days within individual cases were made using paired t-tests. Participants experienced 8% higher RMR during illness, and a subset of these men experienced a mean increase greater than 14%. The participants also experienced 10% lower testosterone levels during illness, and a subset of these participants experienced a mean decrease of 30%, although cortisol levels did not change significantly. These results document elevated RMR following natural pathogen exposure in adult humans, demonstrating that even mild immune reactions can elicit significant increases in energy expenditure. Understanding the costs of immunity and the immunomodulatory actions of hormones are central to understanding the role of immunity in human life history evolution.

Resting metabolic rate and exercise capacity in women with polycystic ovary syndrome

ObjectiveTo assess the resting metabolic rate (RMR) and exercise capacity (or maximal oxygen consumption [VO2 max]) of women with polycystic ovary syndrome (PCOS) and central adiposity. MethodIn a cross-sectional study, RMR was measured by indirect calorimetry and VO2 max by the Astrand test for 31 women with PCOS and 29 controls matched for age and body mass index, but with a different body fat distribution. Differences between the means were analyzed. ResultsThere were no significant differences in RMR or VO2 max values between the 2 groups. ConclusionCentral adiposity was not predictive of an altered RMR or of decreased exercise capacity in women with PCOS.

Effect of High Versus Low Intensity Resistance Exercise on Excess Post Exercise Oxygen Consumption

Resistance training is known to enhance excess post exercise oxygen consumption (EPOC), yet, it is unclear what intensity of resistance exercise is necessary to optimize EPOC. Moreover, it is known that differences in body composition can alter total energy expenditure (EE), yet little is known concerning the effect of body composition on EPOC. PURPOSE: 1) To compare the effect of a single bout of high or low intensity resistance exercise of equal work on EPOC and 2) to determine the effect of body composition on EPOC. METHODS: Ten obese and 10 lean males performed 3 sets of 8 exercises at a low (50% 1 RM) and high intensity (80% 1 RM) of equal work volume. Energy expenditure, respiratory exchange ratio (R), and substrate oxidation were measured at immediately, 1 h, and 2 h post exercise and compared to resting values obtained prior to the exercise bout. RESULTS: Resting metabolic rate (RMR) was significantly higher in the obese group (297.13 ± 43.79 ml/min) compared to the lean group (260.67 ± 28.90 ml/min, p <0.05) but no group differences existed when adjusted for LBM. Post exercise energy expenditure, expressed as mean VO2 and AUC, and R were not significantly (p >0.05) different between the 50% and 80% 1 RM study days. At each post exercise measurement period, a significantly (p <0.05) higher EE existed in the obese group compared to the lean group. Adjusting the post exercise energy expenditure for differences in RMR between the two groups, EE immediately post, 1 h, and 2 h post was no longer significantly different between the obese and lean individuals. CONCLUSIONS Low and high intensity resistance exercise bouts of equal work volume will produce similar post exercise energy expenditure. Moreover, obese and lean men will elicit similar post exercise energy expenditure in response to resistance exercise bouts of varying intensity but equal work volume.

Physical Activity And Resting Metabolic Rate In Overweight Women During Energy Restriction Induced Weight Loss

Obesity prevalence is disproportionately higher in African-American (AA) than Caucasian (CC) women and often is associated with metabolic and behavior differences. AA women have a lower resting metabolic rate (RMR) and a tendency for lower level of physical activity than CC women. PURPOSE The purpose of this study was to compare RMR and physical activity (PA counts) in overweight AA and CC women before and during a 4-wk energy deficit induced weight loss. METHODS Seven pre-menopausal overweight AA women (age: 31.9±6.6 y; weight: 88.1±20.6 kg; BMI: 33.9±6.6; body fat: 44.9±6.6%; lean mass: 45.0±6.9 kg) and 11 CC women (age:28.9±4.8 y; weight:85.5±14.5 kg; BMI: 31.1±4.6; body fat: 47.0±5.0%, lean mass: 43.3±4.7 kg) were recruited for this study. They received diet containing 75% of estimated individual daily energy needs for 4 weeks. Energy needs were assessed from the RMR measured using whole-room indirect calorimetry and an activity factor calculated from the activity level measured using a triaxial accelerometer worn daily on the waist during the whole study period. All meals were provided by the General Clinical Research Center (GCRC) metabolic kitchen for 2 weeks of inpatient stay at the GCRC, followed by 2 weeks of outpatient period. RMR and PA counts were assessed at baseline, mid-point (2 wk) and end of the study (4 wk). PA counts were calculated as a square root of the sum of squared activity counts in 3 dimensions every minute. Body composition was determined by dual-energy x-ray absorptiometry (DXA). RESULTS CC and AA women differed significantly in mean weight loss (3.7±1.7 vs. 1.7±1.9 kg, respectively, p =0.026). AA women had significantly higher lean body mass (LBM) and lower RMR at each time point (both p<0.05). RMR adjusted for LBM was significantly lower after weight loss in both groups (AA women:baseline; 1481±186 kcal/d, at 4th wk; 1451±170 kcal/d, p<0.01; CC women: 1603.3±152 kcal/d, at 4th wk; 1564±144 kcal/d, p<0.01). Average daily PA counts did not differ significantly during the 4-wk study period (220.0±58.7 × 103 vs. 219.2±44.5 × 10 3, p >0.05). CONCLUSIONS Difference in a magnitude of weight change during energy restriction weight loss was not associated with differences in voluntary PA between AA ad CC women but rather to differences in RMR and changes in LBM. Supported by NIH grants RR-00095 and HL 67715

Physical Activity And Resting Metabolic Rate In Overweight Women During Energy Restriction Induced Weight Loss

Obesity prevalence is disproportionately higher in African-American (AA) than Caucasian (CC) women and often is associated with metabolic and behavior differences. AA women have a lower resting metabolic rate (RMR) and a tendency for lower level of physical activity than CC women. PURPOSE The purpose of this study was to compare RMR and physical activity (PA counts) in overweight AA and CC women before and during a 4-wk energy deficit induced weight loss. METHODS Seven pre-menopausal overweight AA women (age: 31.9±6.6 y; weight: 88.1±20.6 kg; BMI: 33.9±6.6; body fat: 44.9±6.6%; lean mass: 45.0±6.9 kg) and 11 CC women (age:28.9±4.8 y; weight:85.5±14.5 kg; BMI: 31.1±4.6; body fat: 47.0±5.0%, lean mass: 43.3±4.7 kg) were recruited for this study. They received diet containing 75% of estimated individual daily energy needs for 4 weeks. Energy needs were assessed from the RMR measured using whole-room indirect calorimetry and an activity factor calculated from the activity level measured using a triaxial accelerometer worn daily on the waist during the whole study period. All meals were provided by the General Clinical Research Center (GCRC) metabolic kitchen for 2 weeks of inpatient stay at the GCRC, followed by 2 weeks of outpatient period. RMR and PA counts were assessed at baseline, mid-point (2 wk) and end of the study (4 wk). PA counts were calculated as a square root of the sum of squared activity counts in 3 dimensions every minute. Body composition was determined by dual-energy x-ray absorptiometry (DXA). RESULTS CC and AA women differed significantly in mean weight loss (3.7±1.7 vs. 1.7±1.9 kg, respectively, p =0.026). AA women had significantly higher lean body mass (LBM) and lower RMR at each time point (both p<0.05). RMR adjusted for LBM was significantly lower after weight loss in both groups (AA women:baseline; 1481±186 kcal/d, at 4th wk; 1451±170 kcal/d, p<0.01; CC women: 1603.3±152 kcal/d, at 4th wk; 1564±144 kcal/d, p<0.01). Average daily PA counts did not differ significantly during the 4-wk study period (220.0±58.7 × 103 vs. 219.2±44.5 × 10 3, p >0.05). CONCLUSIONS Difference in a magnitude of weight change during energy restriction weight loss was not associated with differences in voluntary PA between AA ad CC women but rather to differences in RMR and changes in LBM. Supported by NIH grants RR-00095 and HL 67715