Glucose intolerance and physical inactivity: the relative importance of low habitual energy expenditure and cardiorespiratory fitness

Glucose intolerance and diabetes mellitus are associated with physical inactivity, but it is unclear whether preventive interventions should aim at increasing overall energy expenditure or increasing participation in vigorous, fitness-enhancing activities. Studies aimed at separating and quantifying the effects of these two dimensions of physical activity should use well-validated measurement instruments and employ a study design in which the bivariate error structure of these instruments is determined. In the Isle of Ely Study (Cambridgeshire, United Kingdom), 775 individuals aged 45-70 years in 1994-1997 completed a glucose tolerance test and assessment of 4-day physical activity level (total energy expenditure/basal metabolic rate) by heart rate monitoring, a technique that has been validated against doubly labeled water and whole-body calorimetry. Cardiorespiratory fitness (maximum oxygen uptake (VO2max) per kg)) was measured in a submaximal test. To correct for measurement error, the authors had 190 individuals repeat both tests on three occasions at 4-month intervals. Two-hour glucose level was negatively correlated with physical activity level (men: r = -0.22, p < 0.001; women: r = -0.11, p < 0.05) and VO2max per kg (men: r = -0.18, p < 0.01; women: r = -0.19, p < 0.001) and was positively correlated with age and obesity. The model incorporating bivariate adjustment for measurement error showed that energy expenditure had a major effect on glucose tolerance, but there was less of an effect for cardiorespiratory fitness. These data provide support for public health strategies aimed at increasing overall energy expenditure.     

Quantifying the association between habitual energy expenditure and blood pressure

BACKGROUND: Previous studies have demonstrated an association between physical inactivity and hypertension, but the methods used to assess activity have been subjective and imprecise. Recently methods have become available allowing measurement of energy expenditure in free-living populations. Our aim was to employ these methods to assess the independent association between energy expenditure, cardio-respiratory fitness and blood pressure. METHODS: In a cross-sectional study of 775 people (45-70 years) participating in a continuing population-based cohort study, energy expenditure was assessed by 4 days of heart rate monitoring with individual calibration of the relationship between heart rate and energy expenditure, a method validated against doubly-labelled water and whole body calorimetry. Cardio-respiratory fitness was assessed in a sub-maximal test. To adjust for measurement error in the assessment of usual energy expenditure and fitness, 190 subjects repeated both tests on three further occasions at 4-monthly intervals. RESULTS: A highly significant linear trend in blood pressure was found across quintiles of the physical activity level, the ratio of total energy expenditure to basal metabolic rate. The differences in the mean systolic/diastolic blood pressure between the top and bottom quintile was 6.3/4.4 mmHg in men and 10.7/5.9 mmHg in women. These effects were independent of obesity and cardio-respiratory fitness. Correction for measurement error suggests that the true underlying relationship between usual energy expenditure and blood pressure is stronger still. CONCLUSIONS: These findings are compatible with a strong association between usual energy expenditure and blood pressure and support public health strategies aimed at increasing overall energy expenditure.     

Assessing physical activity in an Asian country: low energy expenditure and exercise frequency among adults in Taiwan

Leisure-time physical activity (LTPA) has been closely related to health improvement. The under-appreciation for energy output by nutritionists stems in part from limited data expressed in caloric equivalent. We converted the frequency, duration, and intensity of LTPA, reported from 15,390 adults in the Taiwan National Health Interview Survey 2001, into kilocalories (kcal). Half of Taiwanese adults admit to no LTPA. Women, lower education or income, younger age, smokers and chewers of betel quid; exercised significantly less than their counterparts. Less than 1/5 (18.9%) of the population in Taiwan was physically active at >or=750 kcal/week, and only 1/7 (13.9%) reached a more desirable goal of >or=1,000 kcal/week, compared with 1/3 in the U.S. The most disconcerting finding was the Taiwan unique U-shaped prevalence for males, with the 25-44 age group being the least active, >or=65 age group being the most active; and S-shaped for females, lowest at age 18-24 years and highest at the two older groups (45-64 and >or=65 years). LTPA was under-appreciated, particularly among the most productive work force (25-44-year group), who exercised with a prevalence only 1/4 of their U.S. counterparts. Expressing LTPA in kcal makes direct comparison easier. Invoking a goal of >or=750 kcal/week for Asians, attainable by exercising 4 hours/week, can facilitate nutritionists in assessing LTPA adequacy. Currently, 4/5 of adults in Taiwan failed to reach this goal. Recognizing the concept of cumulative energy expenditure, in contrast to disciplined daily work for 5 or more days, will encourage the infrequent exercisers such as "weekend warriors" to continue with their activities.     

Prediction of energy expenditure: simplified FAO/WHO/UNU factorial method vs continuous respirometry and habitual energy intake

This study assessed a simple factorial method to predict energy expenditure (EE) in confined and free-living subjects. Thirteen subjects (seven male, 6 female) were studied on four occasions each. Measurements included BMR, 24-h EE by continuous respirometry, 4-d records of intake and activities, body weight, and urine collections. Agreement between measured and predicted 24-h EE was within +/- 2% for group results and +/- 10% for most individuals. Individual agreement was improved to within +/- 5% by using measured rather than predicted BMR. Habitual energy intake was 7.3% greater (p less than 0.05) than predicted EE in males and 5.1% less (NS) in females. Validatory data suggested overrecording of intake in males and underrecording in females. Large individual differences between habitual intake and predicted EE were observed but were significantly (p less than 0.01) correlated with both weight change and protein balance. Our simple factorial method provided acceptable estimates of EE in the subjects studied.     

Twenty-four-hour analysis of elevated energy expenditure after physical activity in a metabolic chamber: models of daily total energy expenditure

BACKGROUND: The Institute of Medicine proposed that 15% of energy expenditure (EE) as excess post-exercise oxygen consumption should be added to additional physical activity energy expenditure (DeltaPAEE) to estimate total EE. However, the magnitude of elevated post-physical activity energy expenditure (EPEE) under normal daily living conditions has not been examined. OBJECTIVE: We examined the effects of EPEE on 24-h EE by modeling standard living conditions in a metabolic chamber. DESIGN: Eleven Japanese men completed three 24-h metabolic chamber measurements: a control day (C-day), a day with high-frequency moderate-intensity physical activity (M-day), and a day with high-frequency vigorous-intensity physical activity (V-day). RESULTS: Mean (+/- SD) 24-h EE for the C-day, the M-day, and the V-day was 2228 +/- 143 kcal, 2816 +/- 197 kcal, and 2813 +/- 163 kcal, respectively. No significant difference was observed in 24-h EE between an M-day and a V-day. Mean EPEEs on the M-day and the V-day did not significantly contribute to increasing 24-h EE. Relative EPEEs to DeltaPAEEs were 6.2 +/- 13.9% (M-day) and 5.1 +/- 9.2% (V-day). However, EPEE/24-h EE was negatively correlated with maximal oxygen uptake on the V-day (r = -0.68, P = 0.02), although no significant correlation between these variables was observed on the M-day (r = -0.41, P = 0.21). CONCLUSIONS: These results suggest that EPEE has a small effect on 24-h EE in the course of normal daily activities, findings that do not support the proposition by the Institute of Medicine for estimating TEE. However, persons with low physical fitness levels could enhance EE as EPEE by increasing vigorous-intensity daily physical activity.     

The extent to which breakfast covers the morning energy expenditure of adolescents with varying levels of physical activity

BACKGROUND: Energy intake at breakfast affects the performance of creativity tests, memory recall and voluntary physical endurance in children before lunch, and food craving during the whole day. OBJECTIVES: To assess the adequacy of breakfast energy supply (BES) and energy expenditure (EE) in adolescents during a schoolday without or with 2 h of physical education lesson (PEL) in the morning. DESIGN: Sixty adolescents (four groups of 14-16 boys and girls aged 12-16 y) participated in a cross-sectional study. Activity patterns and EE were determined by whole-body calorimetry during 36 h and in free-living conditions during 5 days using both a diary and the validated heart rate recording method. BES was determined by weighing individual foods. The pyloric energy flow was assessed using a model of fractional stomach emptying. RESULTS: BES averaged 24.9% (s.d.=6.1) of daily EE in the four groups of subjects. It covered the mean morning EE on a schoolday without PEL, but not in a schoolday with 2 h of PEL in any group. When PEL took place from 8-10 am the cumulative EE exceeded the cumulative pyloric energy flow after 105-150 min, that is during the PEL session, and the energy deficit increased until lunch. With a light breakfast (BES-1 s.d.) energy deficiency happened after 90 min. CONCLUSION: The results stress the need for a heavy breakfast for children and adolescents on the days with PEL in the morning, and a carbohydrate rich snack at 10 am to improve attention, memory and willing participation in physical activities.     

Estimation of energy expenditure from physical activity measures: determinants of accuracy

OBJECTIVE: To describe the determinants, specifically age, body mass index, percentage of body fat, and physical activity (PA) level, associated with over- and underestimation of energy expenditure (EE) using PA records and the Stanford Seven-Day Physical Activity Recall (7DR) compared with doubly labeled water (DLW). RESEARCH METHODS AND PROCEDURES: We collected PA measures on 24 males eating a controlled diet designed to maintain body weight, and we determined EE from DLW and estimated EE from PA records and 7DR. RESULTS: Absolute differences in the estimation of EE between DLW and PA assessment methods were greater for the 7DR (30.6 +/- 9.9%) than PA records (7.9 +/- 3.2%). In PA records, overestimation of EE was greater with older age and higher body fatness; EE was overestimated by 16.7% among men 50 years and older compared with only 5.3% among men <40 years of age. For percentage of body fat, EE was overestimated by 19.7% among men with a percentage of body fat > or =30% compared with only 5.6% among men with a percentage of body fat <25%. A trend for less overestimation of EE with higher levels of PA (measured by DLW/basal metabolic rate [BMR]) also was observed in the PA records. In the 7DR, the estimates of EE varied widely and no trends were observed by age, percentage of body fat, and PA levels. DISCUSSION: Estimation of EE from the 7DR is considerably more variable than from PA records. Factors related to age and percentage of body fat influenced the accuracy of estimated EE in the PA record. Additional studies are needed to understand factors related to accurate reporting of PA behaviors, which are used to estimate EE in free-living adults.     

Estimated energy expenditure and physical activity patterns of adolescent distance runners

The purpose of this study was to examine the estimated total energy expenditure (TEE) and physical activity patterns of adolescent distance runners. Twenty-eight (20 male, 8 female) adolescent distance runners self-reported their daily physical activity with the Bouchard 3-d diary. Mean values for TEE, 57.4 +/- 11.6 and 51.0 +/- 9.8 kcal x kg(-1) x d(-1), and activity energy expenditure (AEE), 26.7 +/- 10.4 and 21.0 +/- 8.8 kcal x kg(-1) x d(-1), when expressed per kilogram body mass were not significantly different between males and females, respectively (P = 0.18). When expressed in absolute terms, TEE, 3609 +/- 927 and 2467 +/- 426 kcal/d, and AEE, 1688 +/- 746 and 977 +/- 269 kcal/d, were significantly higher in males than in females, respectively. The results document the energy expenditure and self-reported physical activity of adolescent distance runners and might be used to address recommendations for adequate dietary energy requirements in this group, which in turn is important for energy balance in the context of normal growth, health, and physical performance.     

Health and fitness series--1. The importance of physical activity for health

Physical inactivity is recognised as a significant, common and preventable risk factor for heart disease, obesity, type II diabetes and osteoporosis. Regular physical activity helps avoid weight gain and plays a part in increasing wellbeing by reducing stress, anxiety and feelings of depression. The author outlines some of the specific health effects of exercise and explains the significance of diet, especially carbohydrates. The article includes some practical health education tips.     

Description and validation of the ActiReg: a novel instrument to measure physical activity and energy expenditure

The ActiReg (PreMed AS, Oslo, Norway) system is unique in using combined recordings of body position and motion alone or combined with heart rate (HR) to calculate energy expenditure (EE) and express physical activity (PA). The ActiReg has two pairs of position and motion sensors connected by cables to a battery-operated storage unit fixed to a waist belt. Each pair of sensors was attached by medical tape to the chest and to the front of the right thigh respectively. The collected data were transferred to a personal computer and processed by a dedicated program ActiCalc. Calculation models for EE with and without HR are presented. The models were based on literature values for the energy costs of different activities and therefore require no calibration experiments. The ActiReg system was validated against doubly labelled water (DLW) and indirect calorimetry. The DLW validation demonstrated that neither EE calculated from ActiReg data alone (EEAR) nor from combined ActiReg and HR data (EEAR-HR) were statistically different from DLW results. The EEAR procedure causes some underestimation of EE >11 MJ corresponding to a PA level >2.0. This underestimation is reduced by the EEAR-HR procedure. The objective recording of the time spent in different body positions and at different levels of PA may be useful in studies of PA in different groups and in studies of whether recommendations for PA are being met. The comparative ease of data collection and calculation should make ActiReg a useful instrument to measure habitual PA level and EE.     

Assessment of physical activity and energy expenditure in epidemiological research of chronic diseases

Physical inactivity has emerged as an important risk factor for a number of diseases, but the typically crude exposure assessments in epidemiological studies, with entailing variation in measurement accuracy, may be a source of heterogeneity contributing to inconsistent results among studies. Consequently, the choice of method for the assessment of physical activity in epidemiological studies is important. Good methods increase our chances of avoiding misclassification and may enhance our understanding of the association between physical activity and health. Since physical activity is also a potential confounder of other lifestyle-health relationships, good methods may enhance our ability to control for confounding. But despite a steadily increasing selection of methods to choose from, no method is suitable for every situation and every population. Although the questionnaire is the most widely used method in epidemiological studies, and laboratory methods are mainly used for validation purposes, improved technology may change our ways of assessing physical activity in the future. This paper describes different methods to measure physical activity and energy expenditure from the epidemiological perspective, and attempts to address the concepts related to the measurement of physical activity.     

Exercise level and energy expenditure in the TAKE 10! in-class physical activity program

This study evaluated the effectiveness of an innovative, classroom-based physical activity prevention program designed to integrate academic curriculum elements along with a physical activity program in providing moderate-to-vigorous intensity physical activity. A convenience sample of three public school classrooms (one first, third, and fifth grade class) was observed implementing the TAKE 10! program while monitored by either CSA accelerometers or digital pedometers. Pedometer step counts and CSA data were recorded for each student and activity. As calculated from CSA data, average MET levels during the activities were 5.72-7.05 (first grade), 5.51-6.77 (third grade), and 4.98-7.19 (fifth grade), and levels were not different between grades (p > 0.05). Average caloric expenditure (Kcal) per 10-minute session was 25.6-27.8 (first grade), 27.6-33.9 (third grade), and 29.7-42.9 (fifth grade). Measured pedometer step counts per session ranged from 644-931 in first grade, 659-1, 376 in third grade, and 1002-1041 in fifth grade. TAKE 10! sessions for all three grades produced exercise levels in the moderate intensity range throughout full duration of the session. Classroom-based physical activity promotion provides a useful strategy to promote meaningful physical activity among school children.     

Occupational physical activity, energy expenditure and 11-year progression of carotid atherosclerosis

OBJECTIVES: This study prospectively assessed the effects of occupational physical activity on atherosclerosis progression. METHODS: This population-based prospective study of ultrasonographically assessed carotid intima media thickness (IMT) used repeated measures of occupational physical activity during baseline, 4-year, and 11-year examinations of 612 Finnish men 42-60 years of age at baseline. The association between five measures of energy expenditure and the 11-year change in maximum IMT was evaluated in regression models adjusting for 21 potential confounders, including biological factors, leisure-time physical activity, smoking, socioeconomic status, psychosocial job factors, and baseline health status. RESULTS: At baseline, 31% of all the men and 51% of those with ischemic heart disease (IHD) exceeded the recommended maximum levels of relative aerobic strain. All five measures of energy expenditure were significantly associated with adjusted 11-year IMT change. Significant interactions were found between IHD and several measures of energy expenditure. Maximum relative aerobic strain resulted in a 90% increase in IMT among the men with IHD compared with a 46% increase among those without IHD. The men with preexisting carotid stenosis also had higher rates of IMT progression than the men without this condition. CONCLUSIONS: This study shows that high energy expenditures at work are associated with an accelerated progression of atherosclerosis even after control for virtually all known cardiovascular risk factors, especially among older workers and workers with preexisting IHD or carotid artery stenosis. The findings support the hemodynamic theory of atherosclerosis and have important implications for workplace surveillance and disease prevention.