Age-related decline in RMR in physically active men: relation to exercise volume and energy intake

Reversal of Soleus Muscle Atrophy in Older Adults: A Non-Volitional Exercise Intervention for a Changing Climate

The World Health Organization recommends that older adults undertake at least 150 minutes of moderate intensity physical activity over the course of each week in order to maintain physical, mental, and social health. This goal turns out to be very difficult for most community dwelling older adults to achieve, due to both actual and perceived barriers. These barriers include personal health limitations, confinement issues, and self-imposed restrictions such as fear of injury. Climate change exacerbates the confinement issues and injury fears among the elderly. To assist older adults in obtaining the benefits of increased physical activity under increasingly challenging climate conditions, we propose a targeted non-volitional intervention which could serve as a complement to volitional physical activity. Exogenous neuro-muscular stimulation of the soleus muscles is a non-invasive intervention capable of significantly increasing cardiac output in sedentary individuals. Long-term daily use has been shown to improve sleep, reduce bone loss, and reverse age-related cognitive decline, all of which are significant health concerns for older adults. These outcomes support the potential benefit of exogenous neuro-muscular stimulation as a complementary form of physical activity which older adults may find convenient to incorporate into their daily life when traditional forms of exercise are difficult to achieve due to barriers to completing traditional physical activities as a result of in-home or in-bed confinement, perceptual risks, or real environmental risks such as those arising from climate change.

Dietary Intake of Masters Athletes: A Systematic Review

Dietary practices of masters athletes (MAs) may promote healthy ageing; however, they are poorly understood. The aims of this systematic review were to synthesise the literature on the dietary intakes of MAs and undertake comparisons between younger (35-50 years) and older (>50 years) MAs and the general population. A search was conducted across seven databases to identify relevant publications for screening and data extraction. Averages for energy intake (EI), macronutrients, and micronutrients were compared with data from the 2011-2012 Australian Health Survey (general population). Twenty-six studies (n = 2819) were included. Energy intake was higher for older (8908 kJ/d versus 7792 kJ/d) but not younger MAs (9073 kJ/d versus 8872 kJ/d) versus the general population. Younger versus older male MAs had higher energy and macronutrient intakes. Energy intake for older was comparable to younger female MAs (7819 kJ/d versus 7485 kJ/d), but older had higher protein, lower carbohydrate, and higher micronutrient intakes. Micronutrient intake was higher in MAs than the general population. Similar EIs for older MAs and younger general population may indicate potential for a higher-quality diet. Younger female MAs may restrict or misreport EI, requiring further investigation. There is a need for more comprehensive assessments of dietary intake in MAs to ascertain diet quality in relation to health.

Historical body temperature records as a population-level 'thermometer' of physical activity in the United States

Over the past two centuries profound technological and social changes have reduced overall levels of physical activity (PA). However, just how much population-level PA levels have declined since the Industrial Revolution is unknown because methods for measuring PA, such as accelerometry and the doubly labeled water technique, were developed only within the last few decades. Here, we show that historical records of resting body temperature (T_B) can serve as a 'thermometer' of population-level PA, enabling us to use the well-documented secular decline in T_B in the US¹ to approximate PA decline in the US since 1820. Using cross-sectional data relating T_B to resting metabolic rate (RMR) and RMR to PA, we estimate that RMR has declined by ∼6% and moderate to vigorous PA by ∼27 minutes per day since 1820 in the US.

The Effects of Lifestyle and Diet on Gut Microbiota Composition, Inflammation and Muscle Performance in Our Aging Society

Living longer is associated with an increased risk of chronic diseases, including impairments of the musculoskeletal and immune system as well as metabolic disorders and certain cancers, each of which can negatively affect the relationship between host and microbiota up to the occurrence of dysbiosis. On the other hand, lifestyle factors, including regular physical exercise and a healthy diet, can affect skeletal muscle and immune aging positively at all ages. Accordingly, health benefits could partly depend on the effect of such interventions that influence the biodiversity and functionality of intestinal microbiota. In the present review, we first discuss the physiological effects of aging on the gut microbiota, immune system, and skeletal muscle. Secondly, we describe human epidemiological evidence about the associations between physical activity and fitness and the gut microbiota composition in older adults. The third part highlights the relevance and restorative mechanisms of immune protection through physical activity and specific exercise interventions during aging. Fourth, we present important research findings on the effects of exercise and protein as well as other nutrients on skeletal muscle performance in older adults. Finally, we provide nutritional recommendations to prevent malnutrition and support healthy active aging with a focus on gut microbiota. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low muscle mass and a higher demand for specific nutrients (e.g., dietary fiber, polyphenols and polyunsaturated fatty acids) that can modify the composition, diversity, and metabolic capacity of the gut microbiota, and may thus provide a practical means of enhancing gut and systemic immune function.

The role of age in the physiological adaptations and psychological responses in bikini-physique competitor contest preparation: a case series

The increased popularity of the bikini-physique competitions has not translated to greater research identifying the influence of age on adaptations during contest preparation. The purpose of this case series was to observe how age may influence the adaptations normally seen during preparation and the exploration of newer protocols to address adaptations more relative to the judging standards. Over a 16-week pre-contest preparation, a 32-y bikini competitor (BC) and 44-y master's bikini competitor (MBC) visited the laboratory bi-weekly to observe changes in body fat mass (BF), lean body mass (LBM), bone mineral density (BMD), total body water (TBW); exploratory measures of deltoid cross-sectional area (DeltCSA), gluteus maximus muscle thickness (GMMT), and subcutaneous adipose tissue thickness (SAT); reproductive hormones estradiol (E2), luteinizing hormone (LH), and energy balance hormones triiodothyronine (T3), leptin and ghrelin; hydration status during contest preparation and the week of competition; resting metabolic rate (RMR); psychometric data related to perceived anxiety, stress, and body image were assessed. No differences between BC and MBC were observed in BF, LBM, BMD, and TBW. Both competitors showed a small loss in LBM. Both BC and MBC showed a contrasting increase in DeltCSA and a loss in GMMT. MBC showed to be slightly more dehydrated (1.025 vs 1.021 g·mL- 1) than BC. Both competitors maintained a euhydration status the day of the competition. No time differences were found between BC and MBC during RMR. BC showed a higher mean difference RMR compared to MBC (2.66 ± 0.75 kcal·kgLBM- 1·d- 1). MBC showed a higher mean difference in LH concentration (84.6 ± 6.01 IU·L- 1), which may be explained by perimenopausal status. MBC had a higher mean difference concentration of leptin (2.51 ± 0.24 ng·mL- 1·kgFM- 1), which was unperturbed by fat loss may be interrelated LH. BC self-reported a higher mean energy intake (15.07 ± 3.43 kcal·kgLBM- 1·d- 1) and higher aerobic training volume (93.26 ± 40.68 min·d). BC and MBC showed similar composition changes, slightly differing metabolic rates, and differing hormonal LH and leptin responses. This finding is in contrast to previous work showing both LH inhibition and leptin diurnal disturbance in younger, female athletes with low energy availability. The exploratory measures may have some benefit for bikini-physique competitors related to the judging criteria. Age did not seem to play a role in contest preparation adaptations.

Nutrition for Older Athletes: Focus on Sex-Differences

Regular physical exercise and a healthy diet are major determinants of a healthy lifespan. Although aging is associated with declining endurance performance and muscle function, these components can favorably be modified by regular physical activity and especially by exercise training at all ages in both sexes. In addition, age-related changes in body composition and metabolism, which affect even highly trained masters athletes, can in part be compensated for by higher exercise metabolic efficiency in active individuals. Accordingly, masters athletes are often considered as a role model for healthy aging and their physical capacities are an impressive example of what is possible in aging individuals. In the present review, we first discuss physiological changes, performance and trainability of older athletes with a focus on sex differences. Second, we describe the most important hormonal alterations occurring during aging pertaining regulation of appetite, glucose homeostasis and energy expenditure and the modulatory role of exercise training. The third part highlights nutritional aspects that may support health and physical performance for older athletes. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low bone and muscle mass and a higher demand for specific nutrients (e.g., vitamin D and probiotics) that may reduce the infection burden in masters athletes. Fourth, we present important research findings on the association between exercise, nutrition and the microbiota, which represents a rapidly developing field in sports nutrition.

Relative energy deficiency in sports (RED-S): elucidation of endocrine changes affecting the health of males and females

The purpose of this review is to present a different perspective of the relative energy deficiency syndrome, to improve understanding of associated endocrine alterations, and to highlight the need for further research in this area. The term "female athlete triad" was coined over 25 years ago to describe three interrelated components: disordered eating, menstrual dysfunction, and low bone mass. The syndrome's etiology is attributed to energy intake deficiency relative to energy expenditure required for health, function, and daily living. Recently, it became clear that there was a need to broaden the term, as the disorder is not an issue of only three interrelated problems but of a whole spectrum of insults resulting from low energy availability (LEA; i.e., insufficient energy availability to cover basic physiological demands) that can potentially affect any exerciser, irrespective of gender. The new model, termed relative energy deficiency in sport (RED-S), has received greater scrutiny in sports medicine due to its effects on both health and performance in athletes of both sexes. RED-S results from low-energy diets (intentional or unintentional) and/or excessive exercise. Energy deficiency reduces hypothalamic pulsatile release of gonadotropin-releasing hormone, this impairing anterior pituitary release of gonadotropins. In women, reduced FSH and LH pulsatility produces hypoestrogenism, causing functional hypothalamic amenorrhea and decreased bone mass. In men, it reduces testosterone and negatively affects bone health. Moreover, LEA alters other hormonal pathways, causing physiological consequences, such as alteration of the thyroid hormone signaling pathways, leptin levels, carbohydrate metabolism, the growth hormone/insulin-like growth factor-1 axis, and sympathetic/parasympathetic tone. This review explains and clarifies the effects of RED-S in both sexes.

Nutrition for Master Athletes: Is There a Need for Specific Recommendations?

Master athletes are often considered exemplars of successful aging, thanks to their capacity to maintain a high sports performance during their entire life. A high training capacity, regular participation in sporting competitions, and delayed alterations in body composition and physiological capacities have been listed among the main factors contributing to impressive master athletes' performances. However, there is a paucity of data on the metabolism and dietary habits of master athletes, and the question of whether they need to adapt their nutrition to the aging process remains open. Herein, the authors presented a contemporary overview of the metabolic challenges associated with aging, including the risk of low energy availability, anabolic resistance, and periods of metabolic crisis due to forced immobilization. After assembling scientific evidence to show that master athletes must adapt their dietary intake, the authors proposed a summary of nutritional recommendations for master athletes and suggested the next stage of research.

Novel Insights into the Pathogenesis of Spinal Sarcopenia and Related Therapeutic Approaches: A Narrative Review

Spinal sarcopenia is a complex and multifactorial disorder associated with a loss of strength, increased frailty, and increased risks of fractures and falls. In addition, spinal sarcopenia has been associated with lumbar spine disorders and osteoporosis, which renders making decisions on treatment modalities difficult. Patients with spinal sarcopenia typically exhibit lower cumulative survival, a higher risk of in-hospital complications, prolonged hospital stays, higher postoperative costs, and higher rates of blood transfusion after thoracolumbar spine surgery. Several studies have focused on the relationships between spinal sarcopenia, appendicular muscle mass, and bone-related problems-such as osteoporotic fractures and low bone mineral density-and malnutrition and vitamin D deficiency. Although several techniques are available for measuring sarcopenia, each of them has its advantages and shortcomings. For treating spinal sarcopenia, nutrition, physical therapy, and medication have been proven to be effective; regenerative therapeutic options seem to be promising owing to their repair and regeneration potential. Therefore, in this narrative review, we summarize the characteristics, detection methodologies, and treatment options for spinal sarcopenia, as well as its role in spinal disorders.

Comparison of association between physical activity and resting metabolic rate in young and middle-aged Korean adults

PURPOSE

The purpose of this study was to comparatively investigate the correlation among body composition, resting metabolic rate (RMR), and physical activity (PA) between young and middle-aged Korean adults.

METHODS

A total of 53 [male n=23, female n=30] subjects were included in this study, among whom 34 subjects were healthy young adults [male n=18, female n=16] and 19 were middle-aged adults [male n=5, female n=14]. The body composition and RMR of all the participants were measured after overnight fasting (≥8 h). The Korean version of the WHO Global Physical Activity Questionnaire (GPAQ) was used to assess physical activity.

RESULTS

Body composition was not significantly different between young adults and middle-aged adults. Whole-body bone mineral density and bone mineral contents (BMC) were significantly lower in middle-aged adults than in young adults. Total blood cholesterol (TC) and blood glucose levels were significantly higher in middle-aged adults (TC; 195.21 ± 43.34, glucose; 103.57 ± 12.61 mg/dL) than in young adults. RMR was significantly lower in middle-aged adults (1619.57 ± 290.28 kcal/day) than in young adults (1894.37 ± 405.00 kcal/day). In middle-aged adults physical activity (PA). PA (METs, min, EE) was inversely correlated with fat mass (FM, kg, and %) and blood triglyceride (TG) level in young adults. In middle-aged adults, PA showed a significant positive correlation with lean body mass (LBM), FM (%), and RMR. Furthermore, PA EE showed significant interrelatedness with BMC among middle-aged adults.

CONCLUSION

These results demonstrated that high PA levels enable LBM and RMR maintenance in middle-aged adults. Furthermore, in young adults, more PA is required to induce change in body composition.

Age-associated changes of resting energy expenditure, body composition and fat distribution in Chinese Han males

Age-related alterations in whole body composition, particularly, reduced fat free mass (FFM) and increased fat mass (FM), lead to a progressive decline in resting energy expenditure (REE). Similarly, regional body composition and fat distribution changes with age might also contribute to an overall lower REE. This study investigated the influence of age on REE, regional body composition and fat distribution, including subcutaneous fat (SF) and visceral fat (VF), in a Chinese Han population as well as their contributions to age-related changes in REE. One hundred and two males aged 31-83 years old underwent dual-energy X-ray absorptiometry (DXA) which measured whole body and regional FM and FFM. SF and VF were measured by magnetic resonance imaging (MRI) and REE by indirect calorimetry. Age was significantly negatively correlated with REE (r = -0.37), total FFM (r = -0.25), upper limbs FFM (r = -0.32), lower limbs FFM (r = -0.34) and showed positive association with trunk FFM (β=0.926). FM, SF and VF decreased in older age groups after an initial rise up to 55-65 years. REE correlated positively to FM, FFM, SF, VF and showed significant association with age (β = -0.254) independent of age-associated changes in body composition. The regional alterations in body composition with age were explained by changes in trunk FFM (β = 0.926). Age-related decline in REE were not solely due to alterations in FM and FFM. Therefore, the changes in regional body composition, fat distribution and REE which occur during aging could be explained by disparities in race, ethnicity, diet, physical activity, and lower specific metabolic rates of FFM components.

Comparison of 3 Nutritional Questionnaires to Determine Energy Intake Accuracy in Iranian Adults

A precision instrument is required to assess the nutritional status. This study was conducted on comparison of 3 nutritional questionnaires to determine energy intake (EI) accuracy in adults in Ravansar Non-Communicable Chronic Disease (RaNCD) cohort study. This cross-sectional study was conducted on 118 of participant's RaNCD. EI was evaluated with 3 questionnaires including food frequency questionnaire (FFQ), 24-hours recall (24HR), and food habits questionnaire (FHQ). Resting metabolic rate (RMR) was measured using indirect calorimetry. We used EI/RMR cut off to evaluate EI reporting status. The mean ± standard deviation of age in men and women were 44.1 ± 6.5 and 43.7 ± 5.25 respectively and 50.8% of participants were men. Among 3 EI estimating questionnaires, FFQ was more accurate than 2 other questionnaires (67.8%). We observed that implausible reporters of 24HR were likely overweight (p < 0.005) but we did not observe a significant difference between EI reporting of FFQ and FHQ with participants' body composition. Our finding showed that EI underreporting of 24HR and FHQ were high. Under reporters were seemed to be overweight. Therefore, these results suggested that among 3 nutritional questionnaires the FFQ was an appropriate approach to determine EI in this population due to plausible EI reporting was higher than 2 other nutritional questionnaires (24HR and FHQ).

Fasting and glucose induced thermogenesis in response to three ambient temperatures: a randomized crossover trial in the metabolic syndrome

BACKGROUND/OBJECTIVES

Cold exposure increases thermogenesis and could improve insulin sensitivity. We hypothesized a blunted response in the metabolic syndrome (MetS).

SUBJECTS/METHODS

Twenty older adults 59 ± 10.4 years (with MetS, MetS+, n = 9; without MetS, MetS-, n = 11) completed a randomized crossover design of 3.5 h exposures to 20, 25 and 27 °C on three visits. After an hour's rest at the desired temperature, resting metabolic rate (RMR), respiratory quotient (RQ), forearm to fingertip gradients (FFG), and in the ear temperature (IET) were measured over 30 min. An oral glucose tolerance test followed, and serial measurements were continued for 2 h. Venous blood was sampled for clinical chemistry, irisin, and fibroblast growth factor 21(FGF21). A mixed model ANCOVA adjusted data for age, gender, fat mass, fat-free mass and seasonality.

RESULTS

There was a significant MetS×temperature interaction where adjusted RMR was significantly higher in MetS+ compared to MetS- by 12% at 20 °C and by 6% at 25 °C, but similar at 27 °C. FFG increased and IET decreased with decreasing temperature to the same extent in both groups. Fasting irisin and FGF21 did not vary with temperature but the former was significantly higher in MetS-. Adjusted postprandial RQ and insulin to glucose ratios were significantly higher at 20 °C relative to 25 °C. Partial correlation analysis of differences between 27 and 20 °C indicated significant positive relationships between fasting as well as postprandial RQ and the respective changes in irisin and FGF21.

CONCLUSIONS

There could be an upward shift of the TNZ in MetS+, but this needs reevaluation.

Ovarian hormones and obesity

BACKGROUND

Obesity is caused by an imbalance between energy intake, i.e. eating and energy expenditure (EE). Severe obesity is more prevalent in women than men worldwide, and obesity pathophysiology and the resultant obesity-related disease risks differ in women and men. The underlying mechanisms are largely unknown. Pre-clinical and clinical research indicate that ovarian hormones may play a major role.

OBJECTIVE AND RATIONALE

We systematically reviewed the clinical and pre-clinical literature on the effects of ovarian hormones on the physiology of adipose tissue (AT) and the regulation of AT mass by energy intake and EE.

SEARCH METHODS

Articles in English indexed in PubMed through January 2016 were searched using keywords related to: (i) reproductive hormones, (ii) weight regulation and (iii) central nervous system. We sought to identify emerging research foci with clinical translational potential rather than to provide a comprehensive review.

OUTCOMES

We find that estrogens play a leading role in the causes and consequences of female obesity. With respect to adiposity, estrogens synergize with AT genes to increase gluteofemoral subcutaneous AT mass and decrease central AT mass in reproductive-age women, which leads to protective cardiometabolic effects. Loss of estrogens after menopause, independent of aging, increases total AT mass and decreases lean body mass, so that there is little net effect on body weight. Menopause also partially reverses women's protective AT distribution. These effects can be counteracted by estrogen treatment. With respect to eating, increasing estrogen levels progressively decrease eating during the follicular and peri-ovulatory phases of the menstrual cycle. Progestin levels are associated with eating during the luteal phase, but there does not appear to be a causal relationship. Progestins may increase binge eating and eating stimulated by negative emotional states during the luteal phase. Pre-clinical research indicates that one mechanism for the pre-ovulatory decrease in eating is a central action of estrogens to increase the satiating potency of the gastrointestinal hormone cholecystokinin. Another mechanism involves a decrease in the preference for sweet foods during the follicular phase. Genetic defects in brain α-melanocycte-stimulating hormone-melanocortin receptor (melanocortin 4 receptor, MC4R) signaling lead to a syndrome of overeating and obesity that is particularly pronounced in women and in female animals. The syndrome appears around puberty in mice with genetic deletions of MC4R, suggesting a role of ovarian hormones. Emerging functional brain-imaging data indicates that fluctuations in ovarian hormones affect eating by influencing striatal dopaminergic processing of flavor hedonics and lateral prefrontal cortex processing of cognitive inhibitory controls of eating. There is a dearth of research on the neuroendocrine control of eating after menopause. There is also comparatively little research on the effects of ovarian hormones on EE, although changes in ovarian hormone levels during the menstrual cycle do affect resting EE.

WIDER IMPLICATIONS

The markedly greater obesity burden in women makes understanding the diverse effects of ovarian hormones on eating, EE and body adiposity urgent research challenges. A variety of research modalities can be used to investigate these effects in women, and most of the mechanisms reviewed are accessible in animal models. Therefore, human and translational research on the roles of ovarian hormones in women's obesity and its causes should be intensified to gain further mechanistic insights that may ultimately be translated into novel anti-obesity therapies and thereby improve women's health.

Forearm to fingertip skin temperature gradients in the thermoneutral zone were significantly related to resting metabolic rate: potential implications for nutrition research

BACKGROUND

Resting metabolic rate (RMR) should be measured in the thermoneutral zone (TNZ). Forearm to fingertip skin temperature gradients (FFG) could serve as an objective measure of this pre-condition.

SUBJECTS/METHODS

Eighty-six adult Australians were studied at 25 °C in a temperature-controlled chamber. Measurements of overnight fasted RMR, respiratory quotient (RQ) and FFG were complemented by clinical biochemistry. McAuley's Index of insulin sensitivity (McA_ISI) and presence of metabolic syndrome was determined. Physical activity was estimated from the short version of the International Physical Activity Questionnaire. Fat mass (FM) and fat-free mass (FFM) were obtained from dual-energy x-ray absorptiometry. Twenty-nine participants were assessed for changes in RMR (ΔRMR), RQ (ΔRQ) and FFG (ΔFFG) following a 6-month free-living period. Multiple linear regression analyses of RMR and RQ on FFG, and of ΔRMR and ΔRQ on ΔFFG were conducted after controlling for 12 known determinants of energy metabolism.

RESULTS

There were wide between-subject variations in unadjusted FFG ranging from -4.25 to +7.8 °C. The final parsimonious model for cross-sectional observations of RMR included age, FM, FFM, McA_ISI and FFG (β=63 kJ/d (95% confidence interval (CI): 14.2, 112.1, P=0.012)). However, FFG was unrelated to RQ.In the longitudinal cohort, adjusted ΔRMR significantly associated only with ΔFFG (β=100 kJ/d (95% CI: 10.3, 189.1; P=0.030)), and adjusted ΔRQ associated with ΔFFG (-0.003 (95% CI: -0.005, 0.0002, P=0.038)), age and McA_ISI.

CONCLUSIONS

Sizeable between-subject variations in FFG at 25 °C were associated with RMR and RQ. Monitoring FFG may serve as an objective assessment of the TNZ during RMR measurements.

The role of DXA in sarcopenia

Sarcopenia is a condition characterized by progressive and generalized reduction in skeletal muscle mass and muscle strength, associated with an increased risk of adverse outcomes (disability, hospitalization, death). The growing attention in the last years, aiming to establish a consensus definition and treatment, reflects the interest of the scientific community toward this complex condition, which has many implications in clinical practice and public health. Dual-energy X-ray absorptiometry (DXA) is the gold-standard technique in the analysis of body composition at molecular level, providing assessment and quantification of fat mass, lean mass and bone mineral content, both in a single body region of interest and at whole-body level. In particular, through the assessment of non-bone lean mass parameters, such as appendicular lean mass adjusted for BMI or height (ALM/BMI and ALM/ht², respectively), it is possible to discriminate subjects with "physiological" loss of muscle mass from those with "pathological" impoverishment of this compartment, referring to specific cutoff values validated in the literature, but keeping in mind the lack of standardization of DXA measures. In addition, it is useful in treatment planning, estimating resting energy expenditure, and in follow-up, because it allows quantifying with high reproducibility the modifications in BC, distinguishing when the change is biological (deterioration due to a progression of the disease or improvement due to treatment). Due to DXA favorability in terms of accuracy, simplicity, availability, low cost and low radiation exposure, its role in sarcopenia diagnosis is becoming increasingly important, emerging as reference assessment technique in muscle mass evaluation.

High resting metabolic rate among Amazonian forager-horticulturalists experiencing high pathogen burden

OBJECTIVES

Resting metabolic rate (RMR) reflects energetic costs of homeostasis and accounts for 60 to 75% of total energy expenditure (TEE). Lean mass and physical activity account for much RMR variability, but the impact of prolonged immune activation from infection on human RMR is unclear in naturalistic settings. We evaluate the effects of infection on mass-corrected RMR among Bolivian forager-horticulturalists, and assess whether RMR declines more slowly with age than in hygienic sedentary populations, as might be expected if older adults experience high pathogen burden.

MATERIALS AND METHODS

RMR was measured by indirect calorimetry (Fitmate MED, Cosmed) in 1,300 adults aged 20 to 90 and TEE was measured using doubly labeled water (n = 40). Immune biomarkers, clinical diagnoses, and anthropometrics were collected by the Tsimane Health and Life History Project.

RESULTS

Tsimane have higher RMR and TEE than people in sedentary industrialized populations. Tsimane RMR is 18 to 47% (women) and 22 to 40% (men) higher than expected using six standard prediction equations. Tsimane mass-corrected TEE is similarly elevated compared to Westerners. Elevated leukocytes and helminths are associated with excess RMR in multivariate regressions, and jointly result in a predicted excess RMR of 10 to 15%. After age 40, RMR declines by 69 kcal/decade (p < .0001). Controlling for lean mass and height accounts for 71% of age-related RMR decline, and adding indicators of infection minimally affects the age slope. The residual level of age-related decline from age 40 is 1.2% per decade.

CONCLUSION

High pathogen burden may lead to higher metabolic costs, which may be offset by smaller body mass or other energy-sparing mechanisms.

Timed Stair Climbing Is the Single Strongest Predictor of Perioperative Complications in Patients Undergoing Abdominal Surgery

BACKGROUND

Current methods to predict patients' perioperative morbidity use complex algorithms with multiple clinical variables focusing primarily on organ-specific compromise. The aim of the current study was to determine the value of a timed stair climb in predicting perioperative complications for patients undergoing abdominal surgery.

STUDY DESIGN

From March 2014 to July 2015, three hundred and sixty-two patients attempted stair climbing while being timed before undergoing elective abdominal surgery. Vital signs were measured before and after stair climb. Ninety-day postoperative complications were assessed by the Accordion Severity Grading System. The prognostic value of stair climb was compared with the American College of Surgeons NSQIP risk calculator.

RESULTS

A total of 264 (97.4%) patients were able to complete the stair climb. Stair climb time directly correlated to changes in both mean arterial pressure and heart rate as an indicator of stress. An Accordion grade 2 or higher complication occurred in 84 (25%) patients. There were 8 mortalities (2.4%). Patients with slower stair climb times had increased complication rates (p < 0.0001). In multivariable analysis, stair climb time was the single strongest predictor of complications (odds ratio = 1.029; p < 0.0001), and no other clinical comorbidity reached statistical significance. Receiver operative characteristic curves predicting postoperative morbidity by stair climb time was superior to that of the American College of Surgeons risk calculator (area under the curve = 0.81 vs 0.62; p < 0.0001). Additionally, slower patients had greater deviations from predicted length of hospital stay (p = 0.034).

CONCLUSIONS

Stair climb provides measurable stress, accurately predicts postoperative complications, and is easy to administer in patients undergoing abdominal surgery. Larger patient populations with a diverse group of operations will be needed to validate the use of stair climbing in risk-prediction models.

Ageing Is Associated with Decreases in Appetite and Energy Intake--A Meta-Analysis in Healthy Adults

It is not well recognized that in the elderly weight loss is more common than weight gain. The aim of this analysis was to determine the effect of ageing on appetite (hunger/fullness) and energy intake, after overnight fasting and in a postprandial state, by meta-analyses of trials that included at least two age groups (>18 years). We hypothesized that appetite and energy intake would be less in healthy older compared with younger adults. Following a PubMed-database systematic search up to 30 June 2015, 59 studies were included in the random-effects-model meta-analyses. Energy intake was 16%-20% lower in older (n = 3574/~70 years/~71 kg/~25 kg/m²) than younger (n = 4111/~26 years/~69 kg/~23 kg/m²) adults (standardized mean difference: -0.77 (95% confidence interval -0.90 to -0.64)). Hunger was 25% (after overnight fasting; weighted mean difference (WMD): -17 (-22 to -13) mm) to 39% (in a postprandial state; WMD: -14 (-19 to -9) mm) lower, and fullness 37% (after overnight fasting; WMD: 6 mm (95% CI: 1 to 11 mm)) greater in older than younger adults. In conclusion, appetite and energy intake are less in healthy older than younger adults, suggesting that ageing per se affects food intake.

Energetics of Aging and Frailty: The FRADEA Study

BACKGROUND

Resting metabolic rate (RMR) and total daily energy expenditure (TDEE) decrease with aging, but it is not known whether frailty modulates this association. We hypothesize that RMR and TDEE values are similar between younger and older nonfrail older adults, whereas they are lower in older prefrail and frail compared with younger adults.

METHODS

A cross-sectional analysis of the FRADEA study, Albacete (Spain), including 402 participants (213 women) older than 70 years (mean age 76 years; range 70-91), was conducted. Estimated RMR (eRMR), oxygen consumption (VO2), expired volume (Ve), and respiratory frequency (RF) were determined using indirect calorimetry; TDEE was determined with the Calcumed instrument; and fat-free mass was determined by bioimpedanciometry. General linear models were used for analysis.

RESULTS

Mean TDEE was 1,889 (SD 470) kcal and eRMR was 1,071 (SD 323) kcal. Both TDEE (B = -24 kcal/day; 95% confidence interval: -35.4 to -14.2; p < .001) and eRMR (B= -15.8 kcal/day; 95% confidence interval: -23.1 to -8.5; p < .001) diminished linearly with age, with lower values in frail and prefrail participants. There was a strong trend between frailty and lower eRMR (F = 2.9; p = .058), with a modifying effect between age and frailty (F = 3.6; p = .002). eRMR in prefrail and frail participants were on average 160 and 114 kcal/day less than that in the nonfrail participants, respectively, and taken together, 154 kcal/day less (F = 5.4; p = .020). Frail and prefrail participants also presented lower Ve and VO2 values that were partially compensated by an RF increase.

CONCLUSION

Frailty status modulates the energy requirements of aging. Frail and prefrail older adults present lower eRMR than nonfrail adults.

Leg strength declines with advancing age despite habitual endurance exercise in active older adults

Age-associated loss of muscle mass (sarcopenia) and strength (dynapenia) is associated with a loss of independence that contributes to falls, fractures, and nursing home admissions, whereas regular physical activity has been suggested to offset these losses. The purpose of this study was to evaluate the effect of habitual endurance exercise on muscle mass and strength in active older adults. A longitudinal analysis of muscle strength (≈4.8 years apart) was performed on 59 men (age at start of study: 58.6 ± 7.3 years) and 35 women (56.9 ± 8.2 years) who used endurance running as their primary mode of exercise. There were no changes in fat-free mass although body fat increased minimally (1.0-1.5%). Training volume (km·wk, d·wk) decreased in both the men and women. There was a significant loss of both isometric knee extension (≈5% per year) and knee flexion (≈3.6% per year) strength in both the men and women. However, there was no significant change in either isokinetic concentric or eccentric torque of the knee extensors. Our data demonstrated a significant decline in isometric knee extensor and knee flexor strength although there were no changes in body mass in this group of very active older men and women. Our data support newer exercise guidelines for older Americans suggesting resistance training be an integral component of a fitness program and that running alone was not sufficient to prevent the loss in muscle strength (dynapenia) with aging.

Resting metabolic rate analysis in chronic hemiparesis patients

The objective of the present study was to compare resting metabolic rate (RMR) of chronic hemiparetic patients to sedentary health individuals. The sample was composed of 16 individuals, that were divided into two groups. The first group had eight hemiparetic patients and the second group was formed by eight sedentary individuals. To access and analyze the gases information a VO2000 analyzer was used. The following variables were measured: VO₂, VCO₂, VE, QR, grams of fat (GrFAT), grams of carbohydrate. RMR was calculated based on Weir’s equation. There was a significant shift on ventilation variables: VE (P<0.0003), VO₂ (P<0.0004) and VCO₂ (P<0.0001) on hemiparetic individuals group when compared to control group. When the energetic substrate used behavior is observed, it shows that fat consumption (represented by GrFAT) is higher on the hemiparetic group when compared to controls (P<0.0001) significant differences were observed for RMR between groups (P<0.0001). RMR showed a correlation to VO₂ on the hemiparetic group (r=0.9277, P=0.0022). To sum up, it was observed through the results that individuals with hemiparesis as a sequel of stroke showed a RMR larger than normal individuals.

Moderate cardiorespiratory fitness is positively associated with resting metabolic rate in young adults

OBJECTIVE

To determine whether moderate cardiorespiratory fitness (CRF) or moderate to vigorous physical activity (MVPA) is associated with elevations in resting metabolic rate (RMR) similar to findings previously observed in endurance athletes.

PARTICIPANTS AND METHODS

Using a cross-sectional design, we measured CRF, RMR, body composition, energy expenditure, and time in MVPA via an arm-based activity monitor in 423 young adults (mean age, 27.6 years). Based on the results of a fitness test, participants were classified into CRF tertiles (low, moderate, or high) by sex.

RESULTS

There were significant differences among the low-, moderate-, and high-CRF groups for mean ± SD body mass index (calculated as the weight in kilograms divided by the height in meters squared) (28.1 ± 4.1, 25.1 ± 3.4, and 23.6 ± 2.5, respectively; P<.001) and fat mass (28.8 ± 9.7, 20.5 ± 8.2, and 14.8 ± 6.5 kg, respectively; P<.001) but not fat-free mass (53.1 ± 11.5, 53.5 ± 12.4, and 54.7 ± 12.1 kg, respectively; P=.49). There were no differences in mean ± SD unadjusted RMR among the groups (1533.2 ± 266.2, 1519.7 ± 267.6, and 1521.9 ± 253.9 kcal/d, respectively). However, after statistical adjustment for differences in body composition, the moderate- and high-CRF groups had a higher RMR compared with low-CRF individuals by 39.7 and 59.9 kcal/d, respectively (P<.05). After further adjustment for MVPA, RMR was higher in the high-CRF group compared with the low-CRF group by 51.2 kcal/d (P<.05).

CONCLUSION

In this large sample of young adults representing a range of CRF, there was a positive stepwise gradient in RMR across tertiles of CRF independent of body composition. Also, MVPA was independently associated with RMR, although this relationship was modest. These findings underscore the multidimensional role of CRF and MVPA on health.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01746186.

Low fitness partially explains resting metabolic rate differences between African American and white women

BACKGROUND

High levels of obesity among African American women have been hypothesized to be partially resultant from a lower resting metabolic rate compared with white women. The aim of the current study was to determine if differences in cardiorespiratory fitness and moderate-to-vigorous physical activity are associated with differences in resting metabolic rate among free-living young adult African American women and white women.

METHODS

Participants were 179 women (white women n = 141, African American women n = 38, mean age = 27.7 years). Resting metabolic rate was measured using indirect calorimetry, body composition using dual energy x-ray absorptiometry, cardiorespiratory fitness via maximal treadmill test, and moderate-to-vigorous physical activity using an activity monitor.

RESULTS

African American women had higher body mass index, fat mass, and fat-free mass compared with white women but lower levels of cardiorespiratory fitness. No differences were observed between African American and white women in resting metabolic rate when expressed as kcal/day (1390.8 ± 197.5 vs 1375.7 ± 173.6 kcal/day, P = .64), but African American women had a lower resting metabolic rate when expressed relative to body weight (2.56 ± 0.30 vs 2.95 ± 0.33 mL/kg/min, P < .001). After statistical adjustment for differences in body composition between groups using linear regression models, African American women had a lower resting metabolic rate compared with white women (1299.4 ± 19.2 vs 1400.4 ± 9.2 kcal/day, P < .001). The addition of cardiorespiratory fitness reduced the differences among groups by 25%. The addition of moderate-to-vigorous physical activity did not improve the model.

CONCLUSIONS

The present study confirms that African American women have a lower resting metabolic rate compared with their white peers, and low cardiorespiratory fitness explained 25% of this difference. Variables associated with resting metabolic rate, such as cardiorespiratory fitness, represent possible points of tailored interventions designed to address high levels of obesity seen in certain demographic groups.

Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults? A systematic review

BACKGROUND

The magnitude of the negative energy balance induced by exercise may be reduced due to compensatory increases in energy intake.

OBJECTIVE

TO ADDRESS THE QUESTION: Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults?

DATA SOURCES

PubMed and Embase were searched (January 1990-January 2013) for studies that presented data on energy and/or macronutrient intake by level of exercise, physical activity or change in response to exercise. Ninety-nine articles (103 studies) were included.

STUDY ELIGIBILITY CRITERIA

Primary source articles published in English in peer-reviewed journals. Articles that presented data on energy and/or macronutrient intake by level of exercise or physical activity or changes in energy or macronutrient intake in response to acute exercise or exercise training in healthy (non-athlete) adults (mean age 18-64 years).

STUDY APPRAISAL AND SYNTHESIS METHODS

Articles were grouped by study design: cross-sectional, acute/short term, non-randomized, and randomized trials. Considerable heterogeneity existed within study groups for several important study parameters, therefore a meta-analysis was considered inappropriate. Results were synthesized and presented by study design.

RESULTS

No effect of physical activity, exercise or exercise training on energy intake was shown in 59% of cross-sectional studies (n = 17), 69% of acute (n = 40), 50% of short-term (n = 10), 92% of non-randomized (n = 12) and 75% of randomized trials (n = 24). Ninety-four percent of acute, 57% of short-term, 100% of non-randomized and 74% of randomized trials found no effect of exercise on macronutrient intake. Forty-six percent of cross-sectional trials found lower fat intake with increased physical activity.

LIMITATIONS

The literature is limited by the lack of adequately powered trials of sufficient duration, which have prescribed and measured exercise energy expenditure, or employed adequate assessment methods for energy and macronutrient intake.

CONCLUSIONS

We found no consistent evidence that increased physical activity or exercise effects energy or macronutrient intake.

Moderate to high levels of exercise are associated with higher resting energy expenditure in community-dwelling postmenopausal women

Postmenopausal women experience an age-related decline in resting energy expenditure (REE), which is a risk factor for energy imbalance and metabolic disease. Exercise, because of its association with greater lean tissue mass and other factors, has the potential to mediate REE decline, but the relation between exercise and REE in postmenopausal women is not well characterized. This study tests the hypothesis that exercise energy expenditure (EEE) is positively associated with REE and can counter the effects of age and menopause. It involves a cross-sectional sample of 31 healthy postmenopausal women (aged 49-72 years) with habitual exercise volumes at or above levels consistent with current clinical recommendations. Subjects kept exercise diaries for 4 weeks that quantified exercise activity and were measured for body composition, maximal oxygen uptake, and REE. Multiple regression analysis was used to test for associations between EEE, age, body composition, and REE. There was a significant positive relation between EEE and lean tissue mass (fat-free mass and fat-free mass index). The relation between REE and EEE remained significant even after controlling for lean tissue mass. These results support the hypothesis that exercise is positively associated with REE and can counter the negative effects of age and menopause. They also indicate a continuous relation between exercise and REE across ranges of exercise, from moderate to high. Exercise at levels that are at or above current clinical guidelines might, in part, ameliorate the risk for energy imbalance and metabolic disease because of its positive relation with REE.

Resistance training induced increase in muscle fiber size in young and older men

Muscle strength and mass decline in sedentary individuals with aging. The present study investigated the effects of both age and 21 weeks of progressive hypertrophic resistance training (RT) on skeletal muscle size and strength, and on myostatin and myogenin mRNA expression in 21 previously untrained young men (26.0 ± 4.3 years) and 18 older men (61.2 ± 4.1 years) and age-matched controls. Vastus lateralis muscle biopsies were taken before and after RT. Type I and type II muscle fiber cross-sectional areas increased more in young men than in older men after RT (P < 0.05). Concentric leg extension increased (P < 0.05) more after 10.5 weeks in young men compared to older men, but after 21 weeks no statistical differences existed. The daily energy and protein intake were greater (P < 0.001) in young subjects. Both myostatin and myogenin mRNA expression increased in older when compared with young men after RT (P < 0.05). In conclusion, after RT, muscle fiber size increased less in older compared to young men. This was associated with lower protein and energy intake and increases in myostatin gene expression in older when compared to young men.

[Muscle activity and energy expenditure]

Most of increases in energy metabolism are induced by exercise. They are related with power and efficiency. In cycle ergometer exercise efficiency is positively correlated with exercise power and negatively correlated with pedaling rate. Ramp exercises are associated with an apparent increase in efficiency. Movements of daily life activity are too complex to make evaluation of power or efficiency possible. Energy expenditure assessment is based on direct measurement of the energy metabolism increase. The energy cost of movement or economy is calculated. Daily activity recording provides an assessment of the energy metabolism ability of patients. Muscle contractile activity is linked with ATP splitting. The pathways to resynthesize ATP include anaerobic glycogenolysis and the aerobic breakdown of substrates. Type I fibres have a higher oxidative capacity than type II fibres. Type II fibres demonstrate a higher glycolytic capacity, contract faster, and are more fatigable. Information relative to energy expenditure during daily life activity allows clinicians to better assess the clinical implications of the stress tests results.

Advantages of dietary, exercise-related, and therapeutic interventions to prevent and treat sarcopenia in adult patients: an update

Sarcopenia is the loss of skeletal muscle mass and function with aging. Although the term sarcopenia was first coined in 1989, its etiology is still poorly understood. Moreover, a consensus for defining sarcopenia continues to elude us. Sarcopenic changes in the muscle include losses in muscle fiber quantity and quality, alpha-motor neurons, protein synthesis rates, and anabolic and sex hormone production. Other factors include basal metabolic rate, increased protein dietary requirements, and chronic inflammation secondary to age-related changes in cytokines and oxidative stress. These changes lead to decreased overall physical functioning, increased frailty, falls risk, and ultimately the loss of independent living. Because the intertwining relationships of these factors are complex, effective treatment options are still under investigation. The published data on sarcopenia are vast, and this review is not intended to be exhaustive. The aim of this review is to provide an update on the current knowledge of the definition, etiology, consequences, and current clinical trials that may help address this pressing public health problem for our aging populations.

Energy expenditure and aging

The study of energy expenditure (EE) has deep roots in understanding aging and lifespan in all species. In humans, total EE decreases substantially in advanced age resulting from parallel changes in resting metabolic rate (RMR) and activity EE. For RMR, this reduction appears to be due to a reduction in organ mass and specific metabolic rates of individual tissues. However, these anatomical changes explain very little regarding the decline in activity EE, which is governed by both genetic and environmental sources. The biological control centers for activity EE are closely coupled with body mass fluctuations and seem to originate in the brain. Several candidate neuromodulators may be involved in the age-related reduction of activity EE that include: orexin, agouti-related proteins and dopaminergic pathways. Unfortunately, the existing body of research has primarily focused on how neuromodulators influence weight gain and only a few studies have been performed in aging models. Recent evidence suggests that activity EE has an important role in dictating lifespan and thus places emphasis on future research to uncover the underlying biological mechanisms. The study of EE continues to unlock clues to aging.

Taxa metabólica de repouso de ciclistas estimada por equações e obtida por calorimetria indireta

A taxa metabólica de repouso (TMR) pode ser determinada por calorimetria indireta (CI). Porém, em função da praticidade, na prática clínica na maioria das vezes esta é estimada por equações de predição, as quais foram desenvolvidas em estudos envolvendo indivíduos não atletas. Apesar de alguns autores terem indicado que tais equações não estimam adequadamente a TMR, estas têm sido bastante utilizadas para calculá-la e prescrever dietas, inclusive para atletas. O objetivo deste estudo foi comparar a TMR determinada por CI com a estimada pelas equações de Harris & Benedict (HB), Schofield, FAO/WHO/UNU e Henry & Rees (HR), em 15 homens ciclistas, de 24,4 ± 3,68 anos, apresentando índice de massa corporal de 21,97 ± 1,46kg/m² e VO2máx de 70,00 ± 5,32mL(kg.min)-1. Para comparar a TMR determinada por CI e pelas equações, utilizou-se o tratamento estatístico testes t de Student (variáveis com distribuição normal) e de Mann-Whitney (variáveis sem distribuição normal), considerando p < 0,05. Além disso, foi realizada correlação de Pearson entre TMR e massa livre de gordura (MLG). Verificou-se que a TMR foi subestimada em 23,5%, 16,7%, 16,8% e 16,9%, respectivamente, quando se utilizaram as equações de HR, FAO/WHO/UNU, Schofield e HB, em relação à TMR obtida por CI. A TMR se correlacionou com a MLG (r = 0,551, p = 0,03). Os resultados confirmam que as equações avaliadas não são adequadas para estimar a TMR em atletas. Tais resultados podem ser explicados pela maior quantidade de MLG apresentada por atletas e possivelmente maior resposta dos receptores β-adrenérgicos aos estímulos do sistema nervoso simpático, resultando em TMR mais alta que em indivíduos sedentários. Diante disso, desenvolveu-se uma equação com as variáveis MLG e idade para melhor estimativa da TMR de ciclistas. Recomenda-se, no entanto, que a equação desenvolvida seja validada em estudo envolvendo um número maior de ciclistas, para que esta seja utilizada na prática clínica.

Post-natal exposure to corticosterone affects standard metabolic rate in the zebra finch (Taeniopygia guttata)

Post-natal stress has been shown to have important short and long term effects on many adult traits in birds. During stress, metabolic alterations often result in the mobilization of energy away from energy-sensitive functions such as growth, which could have significant implications for developing animals. However, little is known about the implications of stress hormones for energy consumption in growing individuals. We experimentally increased corticosterone (CORT) levels in nestling zebra finches via oral administration, between the ages of 7 and 18 days. The standard metabolic rate (SMR) of birds was measured twice overnight when birds were between 11-13 and 55-65 days of age. Developmental CORT administration significantly elevated overnight variability in SMR (sd) in nestling birds (during the treatment period), but not at 55-65 days (5-6 weeks after the treatment period). The effect on variability was seen more prominently in birds from larger brood sizes and in females. We found no effects of our treatments on mean SMR overnight. However, brood size and sex had interactive effects, with males from larger brood sizes having higher SMR at 55-65 days of age. These results suggest that stress hormones can have significant effects on energy metabolism and possibly nocturnal arousal and sleep fragmentation. However, there were no detectable long term effects of our treatments on SMR, suggesting that these effects are only short-lived, in order to maintain homeostasis in the short term.

Aging, resting metabolic rate, and oxidative damage: results from the Louisiana Healthy Aging Study

BACKGROUND

The aging process occurs at variable rates both among and within species and may be related to the variability in oxygen consumption and free radical production impacting oxidative stress. The current study was designed to test whether nonagenarians have a relatively low metabolic rate and whether it is associated with low levels of oxidative stress relative to age.

METHODS

Resting metabolic rate (RMR) and markers of oxidative stress to lipids, proteins, and DNA were measured in three groups of individuals aged 20-34 (n=47), 60-74 (n=49), and>or=90 years (n=74).

RESULTS

RMR, adjusted for fat-free mass, fat mass, and sex, was lower in both older groups when compared to the young group (p<or=.0001). There were no significant differences in urinary isoprostanes, serum protein carbonyls, or DNA fragmentation between groups, and RMR was not related to any markers of oxidative stress.

CONCLUSIONS

This study confirms an age-related decline in RMR independent of changes in body composition but surprisingly did not show an accumulation of oxidative damage with increasing age. Our data challenge the theory that RMR is a significant determinant of oxidative stress and therefore contributes to the aging process.

Energy requirements in frail elderly people: A review of the literature

This review collates studies of healthy, sick, underweight (BMI < or = 21 kg/m2) and very elderly people (> or = 90 yr), in whom resting energy expenditure (REE) was measured using indirect calorimetry. We have observed the following: (1) REE, when adjusted for differences in both body weight and fat-free mass (FFM), is similar in healthy and in sick elderly people being 20 and 28 kcal/kg of FFM per day, respectively, (2) their nutritional status influences their energy requirements given that weight-adjusted REE increases in line with a decrease in BMI, (3) total energy expenditure is lower in sick elderly people given that their physical activity level, i.e. the ratio of total energy expenditure to REE, is reduced during disease averaging at 1.36, (4) energy intake (EI) being only 1.23 x REE is insufficient to cover energy requirements in sick elderly patients, whereas the EI of healthy elderly people appears sufficient to cover requirements, and finally, (5) gender ceases to be a determinant of REE in people aged 60 yr or over, with the Harris & Benedict equation capable of accurately predicting mean REE in this population, whether healthy or sick.

Validation of three predictive equations for basal metabolic rate in adults

Objective

To cross-validate three predictive set of equations for basal metabolic rate (BMR) developed by Schofield (Schofield database), Henry (Oxford database) and Cole (Oxford database) using mean values for age, weight, height and BMR of published studies.

Design

Literature review of studies published from 1985 to March 2002.

Setting

All studies selected used appropriate methods and followed conditions that met the criteria established for basal metabolism, were performed in healthy adults, and were not part of the Schofield or Oxford database.

Subjects

A total of 261 groups of men and women from 175 studies were selected and categorised in three age groups (18.5–29.9, 30.0–59.9, ≥60 years old) and three body mass index (BMI) groups (normal weight, overweight and obese).

Results

Linear regression and concordance correlation analysis showed that the three sets of equations had the same association and agreement with measured BMR, across gender, age, and BMI groups. The agreement of all equations was moderate for men and poor for women. The lowest mean squared prediction errors (MSPRs) were given by Henry equations in men and Cole equations in women. Henry and Cole equations gave lower values than Schofield equations, except for men over 60 years of age. Henry equations were the most accurate in men. None of the three equations performed consistently better in women.

Conclusion

These results support the use of Henry equations in men with a wide range of age and BMI. None of the proposed predictive equations seem to be appropriate to estimate BMR in women.

Effects of exercise training on resting metabolic rate in postmenopausal African American and Caucasian women

Ambiguous findings have been reported in previous studies concerning the relationships between resting metabolic rate (RMR), effects of exercise, and race in postmenopausal women. The purposes of this study were (1) to determine the effect of exercise training on RMR in postmenopausal women and (2) to determine whether this effect is different by race. We analyzed data from 24 African American (AA) (age, 56.3 +/- 5.0 years) and 23 Caucasian (CA) (age, 58.6 +/- 6.1 years) women. RMR was measured by indirect calorimetry after an overnight fast. Subjects completed tests of maximal exercise with metabolic measurements, waist to hip ratio, and body composition. At the completion of all tests, each subject was randomly assigned to either the exercise training or the control group. Aerobic exercise was performed 3 to 4 days per week for 6 months. Intensity was set at 70% to 85% maximal heart rate for 45 to 60 minutes per session. Both AA and CA exercise groups had a significant decrease (P < .05) in body weight (kilograms), percent body fat, and body mass index (BMI) and an increase in aerobic capacity, whereas the control groups did not change. There were no race effects. AA women exhibited significantly lower values than CA women for measured RMR (P < .05). The RMR (kilojoules) of the AA women (both control and exercise groups) decreased over time (P < .05), whereas the RMR of the CA women did not change. Adjusting RMR for BMI or for changes in lean body mass and fat mass did not alter these results. In conclusion, this 6-month endurance-training program did not affect RMR in these postmenopausal women, as RMR did not change in CA women, but decreased significantly over time in both groups of AA women. The factors that contribute to these findings should be the focus of future studies.

The endeavor of high maintenance homeostasis: resting metabolic rate and the legacy of longevity

Metabolism, the continuous conversion between structural molecules and energy, is life in essence. Size, metabolic rate, and maximum life span appear to be inextricably interconnected in all biological organisms and almost follow a "universal" law. The notion of metabolic rate as the natural "rate of living" filled most of the academic discussion on aging in the early 20th century to be later replaced by the free-radical theory of aging. We argue that the rate of living theory was discarded too quickly and that studying factors affecting resting metabolic rate during the aging process may provide great insight into the core mechanisms explaining differential longevity between individuals, and possibly the process leading to frailty. We predict that measures of resting metabolic rate will be introduced in geriatric clinical practice to gather information on the degree of multisystem dysregulation, exhaustion of energy reserve, and risk of irreversible frailty.

Effect of an aerobic exercise training program on resting metabolic rate in chronically beta-adrenergic blocked hypertensive patients

PURPOSE

There is substantial evidence that the use of beta-adrenergic receptor blockers (beta-blockers) is associated with a reduction in resting metabolic rate (RMR) and that a weight gain usually occurs in the first few months of treatment. The purpose of this study was to determine if RMR of overweight and sedentary subjects consuming beta-blockers can be increased following an aerobic exercise training program.

METHODS

Twenty-four subjects participated in the study; 11 (6 women, 5 men) were treated with beta-blockers for hypertension and 13 (9 women, 4 men) were nonmedicated (control group). Body composition, RMR, and peak oxygen uptake (VO2peak) were assessed for all subjects before and after a 12-week aerobic exercise training program. Weekly exercise energy expenditure equaled 83.68 kJ (20 kcal) per kg of body weight while exercise intensity was maintained between 60% and 70% of the VO2 reserve.

RESULTS

Body composition, RMR, and VO2peak did not differ among groups at the beginning of the study. Body weight (-1.4 kg for beta-blockers, P < .05; -2.5 kg for control, P < .05) and VO2peak (+2.2 mL x kg(-1) x min(-1) for beta-blockers, P < .05; +4.1 mL x kg(-1) x min(-1) for control, P < .001) were significantly improved in both groups, whereas RMR (-272 kJ x day(-1) for beta-blockers, NS; +573 kJ x day(-1) for control, P < .05) was increased only in the control group after the aerobic exercise training program.

CONCLUSIONS

These results suggest that beta-blockers limit the increase in RMR normally observed following an aerobic exercise training program. Consequently, obtaining a negative energy balance in an attempt to lose weight may be more difficult.

Nutritional considerations for the older athlete

In this review article, nutritional considerations of the aging athlete are discussed. The focuses of the review include energy, carbohydrate, protein, selected vitamins and minerals, and fluids. Age-associated changes in body composition, resting energy expenditure, and volume and intensity of training, may decrease the need for dietary energy and the intakes of macro- and micronutrients and fluids. The older athlete should monitor nutrient intakes to insure adequacy, especially regarding carbohydrate to promote glucose storage and use as an energy source during exercise, and protein to promote strength-training-induced muscle hypertrophy. Emphasis should also be placed on the dietary intakes of certain micronutrients, as well as the potential need for supplementation of certain vitamins and minerals, including the vitamins B(2), B(6), B(12), D, E, and folate, and the minerals calcium and iron. Age-associated changes in thermoregulation and an increased susceptibility to dehydration underscore the critical importance to the older athlete of adequate fluid intake to sustain health and performance. Nutrition is a tool that the older athlete should use to enhance exercise performance and health.

Análise de taxa metabólica basal e composição corporal de idosos do sexo masculino antes e seis meses após exercícios de resistência

O objetivo deste trabalho foi o de comparar a taxa metabólica basal e a composição corporal antes e após um programa de exercício de resistência. Foram selecionados 46 voluntários do sexo masculino com idade entre 60 e 75 (66,97 ± 4,80 anos), que foram distribuídos aleatoriamente em dois grupos: 1) grupo controle, que foi orientado a não alterar seus hábitos rotineiros e não se engajar em nenhum programa de exercício físico; e 2) grupo experimental, que participou de um programa de exercícios em cicloergômetro três vezes por semana (60 minutos) em dias alternados por seis meses, com intensidade prescrita referente à freqüência cardíaca do limiar ventilatório 1 (LV-1). Os voluntários foram submetidos a avaliação da composição corporal (DEXA); calorimetria indireta, análise sanguínea e teste ergoespirométrico. Após o período de estudo, foram observados decréscimo significativo nos hormônios tireoidianos e mudanças no metabolismo basal em ambos os grupos, mas não foram constatadas alterações na composição corporal. No entanto, o grupo experimental apresentou aumento significativo no consumo de oxigênio pico e na carga de trabalho referente à intensidade do LV-1. Os dados sugerem que um programa de exercícios aeróbios na intensidade do LV-1 não é suficiente para provocar alterações favoráveis no metabolismo basal e composição corporal de idosos, embora promova benefícios cardiovasculares.

High energy flux mediates the tonically augmented beta-adrenergic support of resting metabolic rate in habitually exercising older adults

The sympathetic nervous system contributes to resting metabolic rate (RMR) via beta-adrenergic receptor (beta-AR) stimulation of energy metabolism. RMR and beta-AR support of RMR are greater in habitually exercising compared with sedentary older adults possibly due to greater energy flux (magnitude of energy intake and energy expenditure during energy balance). In 10 older adults regularly performing aerobic endurance exercise (mean +/- se, 66 +/- 1 yr) compared with baseline, a reduction in energy flux (via abstention of exercise and proportional reduction in dietary intake) decreased (P < 0.05) energy expenditure (7746 +/- 440 vs. 9630 +/- 662 kJ.d(-1)), caloric intake (7808 +/- 431 vs. 9433 +/- 528 kJ.d(-1)), RMR (5192 +/- 167 vs. 5401 +/- 209 kJ.d(-1)), and skeletal muscle sympathetic nervous system activity (36 +/- 2 vs. 42 +/- 2 bursts.min(-1)). Significant beta-AR support of RMR was observed at baseline (167 +/- 42 kJ.d(-1)) but not during reduced energy flux. The change in RMR from baseline to reduced energy flux was related to the corresponding change in beta-AR support of RMR (r = 0.77, P = 0.009). No changes were observed in seven time controls (69 +/- 3 yr) who maintained energy flux. High energy flux is a key mechanism contributing to the elevated RMR and beta-AR support of RMR in habitually exercising older adults. Maintenance of high energy flux via regular exercise may be an effective strategy for maintaining energy expenditure and preventing age-associated obesity.

Age-related changes in the metabolism and body composition of three dog breeds and their relationship to life expectancy

We measured body composition and resting metabolic rates (RMR) of three dog breeds (Papillons, mean body mass 3.0 kg (n = 35), Labrador retrievers, mean body mass 29.8 kg (n = 35) and Great Danes, mean body mass 62.8 kg (n = 35)) that varied between 0.6 and 14.3 years of age. In Papillons, lean body mass (LBM) increased with age but fat mass (FBM) was constant; in Labradors, both LBM and FBM were constant with age, and in Great Danes, FBM increased with age but LBM was constant. FBM averaged 14.8% and 15.7% of body mass in Papillons and Labradors, respectively. Great Danes were leaner and averaged only 10.5% FBM. Pooling the data for all individuals, the RMR was significantly and positively associated with LBM and FBM and negatively associated with age. Once these factors had been taken into account there was still a significant breed effect on RMR, which was significantly lower in Labradors than in the other two breeds. Using the predictive multiple regression equation for RMR and the temporal trends in body composition, we modelled the expenditure of energy (at rest) over the first 8 years of life, and over the entire lifespan for each breed. Over the first 8 years of life the average expenditure of energy per kg LBM were 0.985, 0.675 and 0.662 GJ for Papillons, Labradors and Great Danes, respectively. This energy expenditure was almost 60% greater for the smallest compared with the largest breed. On average, however, the life expectancy for the smallest breed was a further 6 years (i.e. 14 years in total), whereas for the largest breed it was only another 6 months (i.e. 8.5 years in total). Total lifetime expenditure of energy at rest per kg LBM averaged 1.584, 0.918 and 0.691 GJ for Papillons, Labradors and Great Danes, respectively. In Labradors, total daily energy expenditure, measured by the doubly labelled water method in eight animals, was only 16% greater than the observed RMR. High energy expenditure in dogs appears positively linked to increased life expectancy, contrary to the finding across mammal species and within exotherms, yet resembling observations in other intra-specific studies. These contrasting correlations suggest that metabolism is affecting life expectancy in different ways at these different levels of enquiry.

Review Article: Sarcopenia: Causes, Consequences, and Preventions

With the onset of advancing age, muscle tissue is gradually lost, resulting in diminished mass and strength, a condition referred to as sarcopenia. The sequela of sarcopenia often contributes to frailty, decreased independence, and subsequently increased health care costs. The following was adapted from an introduction to the conference "Sarcopenia, Age-Related Muscle Loss-Causes, Consequences, and Prevention," sponsored by the Kronos Longevity Research Institute in June 2002. This brief review will introduce potential mechanisms that may contribute to sarcopenia, although no one mechanism has yet, and may not completely, define this process. The only agreed-upon intervention from these proceedings was regular physical exercise, stressing weight-training for elderly men and women. However, even those individuals who maintain their fitness through exercise do not appear to be immune to sarcopenia.

Impaired substrate oxidation in healthy elderly men after eccentric exercise

The metabolic response to eccentric exercise in healthy older adults is unknown. Therefore, substrate metabolism was examined in the basal state and after sustained hyperglycemia (180 min, 10 mM) in eight healthy, sedentary older [66 +/- 2 yr; body mass index (BMI) of 25.5 +/- 1.2 kg/m] and nine younger (23 +/- 1 yr; BMI of 23.6 +/- 1.7 kg/m) men, under control conditions and 48 h after eccentric exercise. Indirect calorimetry was performed to evaluate carbohydrate and lipid oxidation (C(ox) and L(ox), respectively). Eccentric exercise caused muscle soreness and increased plasma creatine kinase in both groups of men (P < 0.02). Although a similar level of hyperglycemia was maintained in the two groups, glucose infusion rates were lower (P < 0.001) in the older men. Compared with basal levels, hyperglycemia stimulated an increase in C(ox) and a decrease in L(ox) during the control and exercise trials in the younger group (P < 0.03), but only during the control trial in the older subjects (P < 0.007). C(ox) was unchanged after eccentric exercise in the younger men [4.00 +/- 0.30 vs. 3.54 +/- 0.44 mg x kg fat-free mass (FFM)(-1) x min(-1); exercise vs. control] but was suppressed by 20% in the older group (3.37 +/- 0.37 vs. 4.21 +/- 0.23 mg x kg FFM(-1) x min(-1); P < 0.04). Moreover, L(ox) was reduced by 38% in the younger subjects (0.47 +/- 0.09 vs. 0.76 +/- 0.10 mg x kg FFM(-1) x min(-1); P< 0.03) but was augmented by 89% in the older group (0.68 +/- 0.11 vs. 0.36 +/- 0.08 mg x kg FFM(-1) x min(-1); P < 0.04). In addition, hyperglycemia-stimulated C(ox), L(ox), and respiratory exchange ratio responses to eccentric exercise were related to abdominal adiposity (r = -0.57, P < 0.04, r = 0.68, P < 0.02 and r = -0.60, P < 0.02, respectively). Despite normal glucose tolerance and the absence of obesity per se, older men experience a reduction in carbohydrate oxidation in response to hyperglycemia after eccentric exercise.

Microgravity as a model of ageing

PURPOSE OF REVIEW

Longevity with good health and long-term survival in space are two of the many challenges that scientists face in the twenty-first century. Ageing and life in space are both associated with undesirable effects on normal physiological processes. This review will outline how the endocrine, metabolic, immune and musculoskeletal systems are affected by microgravity and ageing, drawing analogies between the observed changes in an attempt to highlight common mechanisms.

RECENT FINDINGS

Mild hypothyroidism, increased stress hormones (mainly catecholamines), decreased sex steroids, insulin resistance, impaired anabolic response to food intake, anorexia, altered mitochondrial function and systemic inflammatory response are common features of both ageing and microgravity. Both conditions lead to progressive bone and muscle atrophy, compromising mobility and the ability to perform essential daily tasks. In skeletal muscle, both ageing and space flight lead to weakness from whole muscle to single fibre level, accompanied by marked alterations in muscle architecture and in tendon mechanical properties.

SUMMARY

What makes microgravity an interesting and unique tool for gerontologists is that many space-related physiological changes resemble those observed during ageing, but are more or less quickly restored after re-entry, thus allowing the biology of ageing to be investigated both ways, not only during its development but also during recovery.