Measurement and prediction of energy expenditure in males during household and garden tasks

Outdoor Walking Speeds of Apparently Healthy Adults: A Systematic Review and Meta-analysis

BACKGROUND

Walking outdoors can be used by many individuals to meet public health guidelines for moderate-to-vigorous-intensity physical activity. The speed at which adults walk may be a proxy for intensity. Traditional estimates of indoor walking speed are unlikely to reflect self-selected usual or other instructed paces of outdoor walking speed.

OBJECTIVE

To inform estimates of pace-based walking speed of apparently healthy adults in outdoor settings.

METHODS

We searched four electronic databases for articles published in English between January 1970 and March 2019. Studies that reported walking speed (m/s), cadence (steps/min), or intensity (mL/kg/min) of ambulatory, apparently healthy, and community-dwelling adults (> 18 years) were included. Walking speed categories were defined according to the description provided in each study. Meta-analysis was used to synthesise speed, cadence, and intensity data by slow, usual, medium, fast, and maximal pace (where reported).

RESULTS

Thirty-five studies, representing 14,015 participants (6808 women, 5135 men, and 2072 sex not specified), were identified. The mean (95% CI) walking speed for slow, usual, medium, fast, and maximal pace was 0.82 (0.77-0.86), 1.31 (1.27-1.35), 1.47 (1.44-1.49), 1.72 (1.64-1.81), and 1.62 (1.45-1.79) m/s, respectively. Mean cadence (95% CI) for usual and fast paces were 116.65 (114.95-118.35) and 126.75 (121.87-131.63) steps/min, respectively. The mean oxygen consumption (95% CI) for the usual and medium paces was 11.97 (11.69-12.25) and 13.34 (12.94-13.73) mL/kg/min, respectively.

CONCLUSION

These findings provide greater clarity with regard to how various indicators of enacted walking pace, speed, and intensity overlap and how each can be best communicated in the real-world setting to optimise health-related outcomes. Pace-based instructions can be used to support walking in outdoor settings within public health guidelines.

The role of the super-relaxed state of myosin in human metabolism

Background

The super-relaxed state of myosin (SRX) plays a fundamental role in maintaining the low resting metabolic rate of skeletal muscle. Our previous work on this state has been in animal models. Piperine is a small molecule that has been shown to destabilize the SRX in rabbit fast twitch fibers.

Methods

Here we extend this work to human muscle obtained from biopsies of the vastus lateralis of both lean and obese subjects. The slow release of nucleotides by myosin in the SRX was measured by incubating permeable fibers in a fluorescent analog of ATP and chasing with ATP.

Results

The fraction of myosin heads in the SRX was 0.48 ± 0.04 with a lifetime of 148 ± 5 s in lean subjects and a fraction of 0.41 ± 0.05 and a lifetime of 176 ± 7 s in obese subjects. Addition of 100 μM piperine decreased the SRX population by 43 ± 7% in lean subjects and 36 ± 7% in obese subjects, with little change in lifetimes. Addition of piperine to human cardiac cells had no effect on the SRX, a requirement for a drug to treat metabolic diseases.

Conclusions

In human muscle the SRX and its responses to piperine are similar to those seen previously, with no significant differences between muscles from lean and obese subjects. Thus analogs of piperine that have greater specificity could provide effective treatment for metabolic diseases. The SRX provides a potential mechanism contributing to the large dynamic range of metabolic rate.

Using Metabolic Equivalents in Clinical Practice

Metabolic equivalents, or METs, are routinely employed as a guide to exercise training and activity prescription and to categorize cardiorespiratory fitness (CRF). There are, however, inherent limitations to the concept, as well as common misapplications. CRF and the patient's capacity for physical activity are often overestimated and underestimated, respectively. Moreover, frequently cited fitness thresholds associated with the highest and lowest mortality rates may be misleading, as these are influenced by several factors, including age and gender. The conventional assumption that 1 MET = 3.5 mL O₂/kg/min has been challenged in numerous studies that indicate a significant overestimation of actual resting energy expenditure in some populations, including coronary patients, the morbidly obese, and individuals taking β-blockers. These data have implications for classifying relative energy expenditure at submaximal and peak exercise. Heart rate may be used to approximate activity METs, resulting in a promising new fitness metric termed the "personal activity intelligence" or PAI score. Despite some limitations, the MET concept provides a useful method to quantitate CRF and define a repertoire of physical activities that are likely to be safe and therapeutic. In conclusion, for previously inactive adults, moderate-to-vigorous physical activity, which corresponds to ≥3 METs, may increase MET capacity and decrease the risk of future cardiac events.

An acute bout of housework activities has beneficial effects on executive function

PURPOSE

Although acute bouts of exercise reportedly have beneficial effects on executive function, inactive people may find it difficult to start exercising. In this study, we focused on housework activities (HAs) that generate a sense of accomplishment and require a mild intensity of physical activity. We examined the impact of an acute bout of HA on executive function and oxygenated hemoglobin (oxy-Hb) flow to related cortical regions.

MATERIALS AND METHODS

Twenty-five participants (age, 18-21 years; mean, 19.88±0.60 years; six males and 19 females) underwent two experiments, ie, HA and control experiments, which were conducted on different days. Participants vacuumed a dirty floor in the HA experiment and mimicked the same motion with an unplugged vacuum cleaner on a clean floor in the control experiment.

RESULTS

Heart rate recorded during the experiments showed no significant difference in the intensity of physical activity between control and HA groups. A questionnaire revealed a sense of accomplishment after completing the HA experiment. Participants performed the Stroop color-word task (SCWT) pre- and post-experiments; cortical hemodynamic changes were simultaneously monitored using functional near-infrared spectroscopy. Variation in Stroop interference scores for SCWT total response between pre- and post-experiments was signifi-cantly higher in the HA group than in the control group, and that for SCWT correct response showed a similar trend. Variation in the Stroop interference score for oxy-Hb flow to the right ventrolateral prefrontal cortex (R-VLPFC) showed the same trend.

CONCLUSION

Thus, HAs may have a greater beneficial effect on executive function than other physical activities through the activation of PFC, including R-VLPFC.

Comparing the standards of one metabolic equivalent of task in accurately estimating physical activity energy expenditure based on acceleration

The purpose of the study is to analyse how the standard of resting metabolic rate (RMR) affects estimation of the metabolic equivalent of task (MET) using an accelerometer. In order to investigate the effect on estimation according to intensity of activity, comparisons were conducted between the 3.5 ml O₂ · kg^-1 · min^-1 and individually measured resting VO₂ as the standard of 1 MET. MET was estimated by linear regression equations that were derived through five-fold cross-validation using 2 types of MET values and accelerations; the accuracy of estimation was analysed through cross-validation, Bland and Altman plot, and one-way ANOVA test. There were no significant differences in the RMS error after cross-validation. However, the individual RMR-based estimations had as many as 0.5 METs of mean difference in modified Bland and Altman plots than RMR of 3.5 ml O₂ · kg^-1 · min^-1. Finally, the results of an ANOVA test indicated that the individual RMR-based estimations had less significant differences between the reference and estimated values at each intensity of activity. In conclusion, the RMR standard is a factor that affects accurate estimation of METs by acceleration; therefore, RMR requires individual specification when it is used for estimation of METs using an accelerometer.

Gross and relative energy cost of domestic household activities in Asian men

BACKGROUND/OBJECTIVES

Obesity is on the rise and participation in exercise has declined. Domestic household activities may help meet the recommended daily physical activity levels. This study aimed to measure the energy costs of household activities among Asian males.

SUBJECTS/METHODS

This was a randomised cross-over study conducted in a whole-body calorimeter. The energy costs of 14 domestic household activities, divided into two studies, were measured in 10 healthy Asian males. Participants' weight, height, body composition and basal metabolic rate were measured on the first test visit. A standard breakfast was served and participants rested for an hour before the measurement of energy costs of domestic household activities. During the measurements, each activity was performed for 20 min, and participants rested for 30 min between activities.

RESULTS

The mean energy costs of domestic household activities ranged from 5.92 to 11.97 kJ/min, which were significantly different between activities (repeated measures analysis of variance, P<0.001). When expressed as metabolic equivalents (METS), all domestic household activities were classified as low-intensity physical activities. Actual METS (METS_actual) were significantly different to standard METS of eight activities, which may be partly explained by the universal assumption of 3.5 ml O₂/kg/min made during the calculation of METS in the Asian population.

CONCLUSIONS

The energy costs of a range of domestic household activities reported in this study may assist in the planning of physical activities among Asians to meet national physical activity guidelines.

Metabolic rate prediction in young and old men by heart rate, ambient temperature, weight and body fat percentage

OBJECTIVES

An estimation of metabolic rate (MR) is needed to determine wet-bulb globe temperature (WBGT) reference values in order to reduce heat strain in physical workers. The aim of this study was to develop MR prediction equation for younger and older men in hot working environments.

METHODS

We measured the MR and heart rate (HR) of both younger and older men at ambient temperatures (Ta) of 25, 30 and 35°C while they cycled on a bicycle ergometer at a workload of 30, 45 and 60% of maximal oxygen uptake (V̇O2max). Seven younger male university students aged 22.9 ± 0.7 (mean ± SD) years and seven older male workers aged 61.7 ± 2.2 (mean ± SD) years participated in this study. MR, HR and rectal temperature (Tre) were measured during the study. HR, ambient temperature (Ta), body weight (BW) and body fat percentage (BF) served as predictors of MR using multivariate analysis. To increase the MR prediction accuracy, the following three alternative predictors of HR were used: HRres, calculated as 100 × [(HR - resting HR) / (maximal HR - resting HR)]; HRnet, calculated as (HR - resting HR); and HRi, calculated as (HR / resting HR).

RESULTS

The R(2) value indicated that the models with HRres or HRnet were more accurate than those with HRi or HR. Ta had a significantly positive correlation with MR in older men. BW had a significantly positive correlation with MR in both younger and older men, and BF had a significantly negative correlation with MR in both younger and older men.

CONCLUSIONS

HRres or HRnet enabled more accurate MR prediction than HR. BW and BF would increase the accuracy of MR prediction.

Accelerometry and salivary cortisol response during Air Force Special Tactics Officer selection

Background

Special Tactics Officer (STO) selection is conducted to select officers to enter the combat controller training pipeline. The aims were to determine physical activity patterns, estimate energy expenditure, and identify whether return and/or unsuccessful candidates demonstrated differences in cortisol responses compared to non-selected and/or first-time attendees.

Methods

Participants completed the STO selection, consisting of 5 days of physical and mental challenges. Participants were equipped with ActiCals®, and saliva samples were collected throughout the STO selection.

Results

Average activity counts were 684 ± 200 counts∙min⁻¹, with no group differences. Estimated energy expenditure was 4,105 ± 451 kcal∙day⁻¹. Cortisol was elevated following extended physical training but returned to baseline during rest. Return candidates had significantly lower cortisol responses compared to first-timers, 0.43 ± 0.06 μg∙dl⁻¹ versus 0.76 ± 0.18 μg∙dl⁻¹, respectively, p < 0.05.

Conclusions

An individual's salivary cortisol response to the stresses incurred during the STO selection has the potential to be incorporated into the entire picture of a candidate's performance and ability to handle stress.

Step rate-determined walking intensity and walking recommendation in Chinese young adults: a cross-sectional study

There is lack of data on the physiological characteristics of over ground walking and walking recommendations for Chinese young adult. The purpose of the study was to measure walking-related energy expenditure during field testing, to identify step-rate cut-point associated with moderate and vigorous intensity, and to translate physical activity (PA) guidelines into walking goals for Chinese young adults.

DESIGN

Cross-sectional analytic study.

SETTING

Two communities from Beijing and Shanghai in China.

PARTICIPANTS

A sample of 226 Chinese adults (117 men, 109 women) with a mean age of 21.7 (±0.2) years, volunteered to participate in the study. All Participants were recreationally active without orthopaedic limitations, free of chronic diseases, not taking any medications that affect metabolism and non-smokers.

OUTCOME MEASURES

All the participants completed four 6 minincremental over ground walking at different speeds of 3.8, 4.8, 5.6 and 6.4 km/h, respectively. Indirect calorimeter was used to measure energy expenditure at each speed. Receiver operating characteristic curves were used to determine the step-rate cut-points associated with moderate and vigorous intensity activity.

RESULTS

At the same walking speed, step counts per minute were higher in women than in men. No significant differences were found in VO(2) per weight (ml/kg/min) between women and men. Step-rate cut-point associated with walking at 3 metabolic equivalents (METs) and 6METs were 105 and 130 step/min when analysing men and women together. There were slight differences on the cut-points between women and men if data were analysed separately.

CONCLUSIONS

In order to meet PA guidelines, Chinese young adult should walk 30 min with at least 105 step/min or 3150 steps or 2 km with the same step-rate per day. Walking at a higher speed of 130 step/min might provide additional health benefit.

Substrate metabolism during basal and hyperinsulinemic conditions in adolescents and young-adults with Barth syndrome

BACKGROUND

Barth syndrome (BTHS) is a rare X-linked disorder that is characterized by mitochondrial abnormalities, infantile or childhood onset of cardioskeletal myopathy, and high mortality rates. It is currently unknown if BTHS related mitochondrial dysfunction results in substrate metabolism abnormalities and thereby contributes to cardioskeletal myopathy in patients with BTHS.

METHODS

Adolescents and young adults with BTHS (n = 5, 20 ± 4 yrs) and age and activity matched healthy controls (n = 5, 18 ± 4 yrs) underwent an hyperinsulinemic-euglycemic clamp procedure with stable isotopically labeled tracers for measurement of lipolysis, fatty acid oxidation, glucose disposal, and whole-body proteolysis rates; dual energy x-ray absorptiometry for measurement of body composition and 2-D and strain echocardiography for measurement of left ventricular function.

RESULTS

Participants with BTHS had lower fat-free mass (FFM) (BTHS: 31.4 ± 6.9 vs.

CONTROL

46.7 ± 5.3 kg, p < 0.005), lower systolic function (strain, BTHS: -15.2 ± 2.4 vs.

CONTROL

-19.0 ± 2.4 %, p < 0.05), greater insulin-stimulated glucose disposal rate per kg FFM (BTHS: 96.5 ± 16.3 vs.

CONTROL

67.4 ± 17.6 μmol/kgFFM/min, p < 0.05), lower basal (BTHS: 4.6 ± 2.7 vs.

CONTROL

11.9 ± 4.4 μmol/kgFM/min, p < 0.05) and hyperinsulinemic (BTHS: 1.6 ± 0.4 vs.

CONTROL

3.6 ± 1.6 μmol/kgFM/min, p < 0.05) lipolytic rate per kg fat mass (FM), and a trend towards higher basal leucine rate of appearance per kg FFM (BTHS: 271.4 ± 69.3 vs.

CONTROL

193.1 ± 28.7 μmol/kgFFM/hr, p = 0.07) compared to controls. Higher basal leucine rate of appearance per kg FFM (i.e. whole-body proteolytic rate) tended to be associated with lower left ventricular systolic strain (r = -0.57, p = 0.09).

CONCLUSION

Whole-body fatty acid, glucose and amino acid metabolism kinetics when expressed per unit of body composition are altered and appear to be related to cardioskeletal myopathy in humans with BTHS. Further studies examining myocardial substrate metabolism and whole-body substrate metabolism during increased energy demands (e.g., exercise) and their relationships to skeletal and cardiac function are recommended.

How long does it take to achieve steady state for an accurate assessment of resting VO₂ in healthy men?

The time necessary to obtain a steady state for an accurate and reliable assessment of resting [Formula: see text] remains unclear and was the purpose of this study. Thirty healthy men, aged 17-28 years, visited the laboratory twice for the assessment of resting [Formula: see text], which was assessed as follows: (a) 24 h abstention from physical exercise, alcohol, soft drinks and caffeine, (b) fasting for at least 8 h, (c) an acclimation period of 10 min, and (d) 60 min assessment in a supine position. Resting [Formula: see text] significantly changed during the 60 min (F = 37.4, P < 0.001), exhibiting a monoexponential decrease before reaching an asymptote. Post hoc pairwise comparisons showed that significant differences existed between consecutive means until the 30 min time point, after which there were no significant differences. The [Formula: see text] response across trials exhibited high test-retest reliability, with within-subject coefficients of variations at each time point ranging from 2.8 to 7.0 % and intraclass correlation coefficients ranging from 0.90 to 0.99. The reliability was higher from the 25 min time point onwards. Based on these findings, the following recommendations are made to promote accurate assessment of resting [Formula: see text]: (a) initiate the resting [Formula: see text] measurement with 10 min of acclimation to the assessment apparatus, (b) determine resting [Formula: see text] for a minimum of 30 min, until an apparent [Formula: see text] steady state has been achieved; and (c) determine resting [Formula: see text] for a further 5 min, with the average of this last 5 min of data being regarding as the resting [Formula: see text].

Absolute and relative energy costs of walking in a Brazilian adult probability sample

BACKGROUND

Walking is commonly recommended for enhancing energy expenditure (EE), a basic principle in weight management, and cardiorespiratory fitness. However, walking EE varies with characteristics of a given population, especially by sex and age.

PURPOSE

The study's purpose was to measure EE of walking as influenced by physical and physiological characteristics of a sample of adults (≥ 20 yr) living in Niterói, Rio de Janeiro, Brazil.

METHODS

Walking EE and HR were measured during a submaximal multistage treadmill test. The test stages lasted for 3 min each and started at a speed of 1.11 m·s(-1) and a grade of 0%. In the second stage, the grade was maintained at 0%, but the speed was increased to 1.56 m·s(-1) and maintained at this speed but with grade raised by 2.5% at each stage until 10% at stage 6. We measured resting oxygen consumption (MET m) before the test with the participants sitting quietly.

RESULTS

MET m (mL O2·kg(-1)·min(-1), mean ± SE) was lower both in women (2.85 ± 0.03) and in men (2.97 ± 0.04) by almost 19% and 15%, respectively, compared with the conventionally estimated MET (METe) of 3.5 mL O2·kg(-1)·min(-1). Walking EE for any given speed and grade had an absolute intensity, expressed as multiples of MET m or MET e, that was practically equal between sexes and age groups, but it incurred higher individual physiological demand or relative intensity for women and older adults.

CONCLUSIONS

Resting EE reflected by using METe is overestimated in the adult population of Niterói. Prescription of activities to counteract the existing worldwide obesity epidemic should be ideally based on individual physiological information, especially among women and older individuals.

Estimating oxygen consumption from heart rate and heart rate variability without individual calibration

Heart rate (HR) as an estimator of oxygen consumption (VO(2) ) usually requires HR to be individually calibrated in a separate test. This study examined the validity of a new HR - and HR variability-based method (Firstbeat PRO heartbeat analysis software) in the estimation of VO(2) in real-life tasks. The method takes into account the respiration rate determined from HR variability and the differences in the on/off dynamics of HR and VO(2) , and no calibration tests are needed. Ten men and nine women performed 25 tasks representing different types of daily activities. Portable devices were used to measure R-to-R intervals (ECG), VO(2) and respiration rate. In pooled regression analysis, the estimated VO(2) accounted for 87% of the variability in the actual VO(2) , SEE 3·5 ml min(-1) kg(-1) (1 MET). At group level, the method underestimated slightly the measured VO(2) (mean difference - 1·5 ml min(-1) kg(-1) or - 0·4 METs). Some of the values at low exercise intensities were markedly underestimated, but the agreement was better during light and heavy activities. The limits of agreement for the data were from -8·4 to 5·4 ml min(-1) kg(-1) or from -2·4 to 1·5 METs. At individual level, the average deviations of the predicted VO(2) ranged from -1·0 to 0·6 METs and R(2) from 0·77 to 0·94, respectively. The present data indicate that the prediction method may be considered sufficiently accurate to determine the average VO(2) in field use, but it does not allow precise estimation of VO(2) .

Energy expenditure during golfing and lawn mowing in older adult men

This study compared the intensity and energy cost of playing 9 holes of golf with 40 min of lawn mowing in older men and determined whether both met the current recommendations for health benefits. Eighteen men (age 71.2 +/- 4.4 yr, BMI 27.3 +/- 2.3; M +/- SD) completed a graded treadmill test. During golfing and lawn-mowing field tests, oxygen consumption and walking velocity and distance were measured using a portable metabolic system and global positioning system receiver. The net energy costs of golfing and lawn mowing were 310 and 246 kcal, respectively. The average intensities in metabolic equivalents of golfing and lawn mowing were 2.8 +/- 0.5 and 5.5 +/- 0.9, respectively. Both lawn mowing and golfing met the original intensity and energy expenditure requirements for health benefits specified by the American College of Sports Medicine in 1998, but only lawn mowing met the 2007 intensity recommendations.

Desafios na medição quantitativa da ingestão alimentar em estudos populacionais

A avaliação da ingestão alimentar em populações é uma medida cada vez mais presente em estudos epidemiológicos para a investigação da relação entre nutrição e doenças crônicas não transmissíveis já que as atuais recomendações indicam a necessidade de se manter uma vida ativa com controle da ingestão alimentar. A medida da ingestão alimentar quantitativa é geralmente feita por meio de recordatório (ou diário) alimentar de 24h ou por questionários semiquantitativos de freqüência alimentar. O presente artigo discute os principais fatores que envolvem a obtenção e a análise dessas informações, particularmente no que diz respeito à ingestão energética. Fica evidente a necessidade de aprimorar as condições de obtenção das informações sobre as porções ingeridas, as tabelas de composição química de alimentos e da estimativa do gasto energético para a determinação das recomendações energéticas.

A Re-examination of the Metabolic Equivalent Concept in Individuals With Coronary Heart Disease

OBJECTIVE

The metabolic equivalent (MET) is a commonly used method of quantifying the energy cost and intensity of physical activity. Recent studies have questioned the accuracy of the well-accepted value of a MET of 3.5 mL O2.kg(-1).min(-1). The goal of the present study was to compare the traditionally accepted value for 1 MET to direct measures of resting metabolic rate in a group of stable individuals with coronary heart disease (CHD).

METHODS

The primary cohort consisted of 109 (60 men and 49 women) subjects with documented coronary heart disease and a body mass index >or=25 kg/m2. Measurements included indirect calorimetry, body composition, and exercise capacity (peak oxygen uptake [VO2]). In a substudy of 17 (10 men, 7 women) normal weight subjects (body mass index <25 kg/m2), metabolic rate in the seated position was also measured.

RESULTS

Mean resting value for 1 MET was a VO2 value of 2.58 +/- 0.4 mL O2.kg(-1).min(-1) for overweight subjects measured in the supine position and 2.84 +/- 0.59 mL O2.kg(-1).min(-1) for normal weight individuals measured in the seated position. Caloric expenditure value was 0.74 +/- 0.12 kcal.kg(-1).h(-1) rather than the expected value of 1 kcal.kg(-1).h(-1). Values were similar between men and women. Women on beta-blockers had a lower resting metabolic rate (2.47 +/- 0.27 vs. 2.71 +/- 0.38 mL O2.kg(-1).min(-1)) (P < .05) than women not on beta-blocker therapy, whereas there was no effect of beta-blockers in men.

CONCLUSIONS

Findings confirm recent studies of otherwise healthy individuals and indicate that the average resting metabolic rate in subjects with coronary heart disease is 23% to 36% lower than the widely accepted value of 3.5 mL O2.kg(-1).min(-1). Results demonstrate the limitation of the convention of expressing energy expenditure in multiples of an assumed constant.

Self-selected exercise intensity during household/garden activities and walking in 55 to 65-year-old females

This study determined whether some of the more vigorous household and garden tasks (sweeping, window cleaning, vacuuming and lawn mowing) were performed at a moderate intensity (3-6 METs or metabolic equivalents) by a representative sample of 50, 55 to 65-year-old women (X +/- SD; 59.3 +/- 3.1 years, 161.5 +/- 5.2 cm, 69.4 +/- 12.4 kg, 38.4 +/- 7.3% BF). Data collection was conducted in a standardised laboratory environment and in the subjects' homes. Energy expenditure during self-perceived moderate paced walking around a quadrangle was also used as a marker of exercise intensity. Energy expenditure measured via indirect calorimetry was also predicted from: HR, CSA accelerometer counts, Quetelet's index and the Borg rating of perceived exertion. Ninety-six percent of the subjects walked at an intensity of >or= 3.0 METs. Except for vacuuming in the laboratory (X = 2.9 METs; P = 0.19), the intensity of each of the other activities was significantly (P </or= 0.002) greater than 3.0 METs. Subjects swept (3.7 vs. 3.3 METs) and vacuumed (3.6 vs. 2.9 METs) at greater intensities in the home than in the laboratory, whereas the converse applied to window cleaning (3.3 vs. 3.6 METs) and lawn mowing (4.9 vs. 5.5 METs). Eighty-six percent (172 out of 200) of the VO2 measurements were >or= 3.0 METs when the four household/garden activities were performed in the subjects' homes. These activities therefore have the potential to contribute to the 30 min day(-1) of moderate intensity physical activity required to confer health benefits but there was much inter-individual variability in the intensity at which these tasks were performed. Random intercept regression analyses yielded prediction equations with 95% confidence intervals of +/- 0.80 and +/- 0.84 METs for the laboratory and home based equations, respectively. Considering the means for the five activities ranged from 2.9 to 5.5 METs, these 95% confidence intervals lack predictive precision at the individual level. Nevertheless, the laboratory and home-based equations predicted with correct classification rates of 89 and 90%, respectively, whether energy expenditure was < 3.0 or >or= 3.0 METs.

Development and evaluation of an activity measure for people with spinal cord injury

PURPOSE

To develop and conduct a preliminary assessment of the content validity, test-retest reliability, and convergent validity of the Physical Activity Recall Assessment for People with Spinal Cord Injury (PARA-SCI), a new physical activity measure for people with SCI.

METHODS

The scale format, interview guidelines, and activity intensity classification system were developed and content validated using qualitative and quantitative methodologies in multiple samples of people with SCI and their caregivers. Test-retest reliability (1-wk interval) was examined by administering the PARA-SCI via telephone to 102 men and women with SCI. Convergent validity was examined by assessing relationships between PARA-SCI scores and activity levels as determined by indirect calorimetry (N = 14).

RESULTS

In the reliability study, intraclass correlations ranged from 0.45 to 0.91 for the various PARA-SCI activity categories and intensities. In the validity study, correlations between PARA-SCI scores and indirect calorimetry estimates of activity ranged from 0.27 to 0.88.

CONCLUSIONS

The PARA-SCI shows promise as a measure of physical activity for people with SCI. Further validation research is encouraged using broader samples and alternative validation techniques.

Predicting walking METs and energy expenditure from speed or accelerometry

PURPOSE

a) Compare the predictive potential of speed and CSA(hip) (Computer Science Applications accelerometer positioned on the hip) for level terrain walking METs (1 MET = VO2 of 3.5 mL.kg(-1).min(-1)) and energy expenditure (kcal.min(-1)); b) cross-validate previously published CSA(hip)- and speed-based MET and energy expenditure prediction equations; c) measure self-paced walking speed, exercise intensity (METs) and energy expenditure in the middle aged population.

METHODS

Seventy-two 35- to 45-yr-old volunteers walked around a level, paved quadrangle at what they perceived to be a moderate pace. Oxygen consumption was measured using the criterion Douglas bag technique. Speed, CSA(hip), heart rate, and Borg rating of perceived exertion were also monitored.

RESULTS

Speed explained 10% more variance of walking METs than CSA(hip). Speed and mass explained 8% more variance of walking energy expenditure (kcal.min) than CSA(hip) and mass. The best previously published regression equations predict our walking METs and energy expenditures within 95% prediction limits of +/- 0.7 METs and +/- 1.0 kcal.min(-1), respectively. Women paced themselves at a significantly higher mean speed (5.5 km.h(-1)) and intensity (4.1 METs) than their male counterparts (5.2 km.h(-1) and 3.8 METs). Both genders expended approximately 0.75 kcal.kg(-1) for every kilometer of level terrain walked.

CONCLUSION

Speed-based MET and energy expenditure predictions during level terrain walking were more accurate than those utilizing CSA(hip).

Metabolic equivalent: one size does not fit all

The metabolic equivalent (MET) is a widely used physiological concept that represents a simple procedure for expressing energy cost of physical activities as multiples of resting metabolic rate (RMR). The value equating 1 MET (3.5 ml O2·kg−1·min−1 or 1 kcal·kg−1·h−1) was first derived from the resting O2 consumption (V̇o2) of one person, a 70-kg, 40-yr-old man. Given the extensive use of MET levels to quantify physical activity level or work output, we investigated the adequacy of this scientific convention. Subjects consisted of 642 women and 127 men, 18–74 yr of age, 35–186 kg in weight, who were weight stable and healthy, albeit obese in some cases. RMR was measured by indirect calorimetry using a ventilated hood system, and the energy cost of walking on a treadmill at 5.6 km/h was measured in a subsample of 49 men and 49 women (26–45 kg/m2; 29–47 yr). Average V̇o2 and energy cost corresponding with rest (2.6 ± 0.4 ml O2·kg−1·min−1 and 0.84 ± 0.16 kcal·kg−1·h−1, respectively) were significantly lower than the commonly accepted 1-MET values of 3.5 ml O2·kg−1·min−1 and 1 kcal·kg−1·h−1, respectively. Body composition (fat mass and fat-free mass) accounted for 62% of the variance in resting V̇o2 compared with age, which accounted for only 14%. For a large heterogeneous sample, the 1-MET value of 3.5 ml O2·kg−1·min−1 overestimates the actual resting V̇o2 value on average by 35%, and the 1-MET of 1 kcal/h overestimates resting energy expenditure by 20%. Using measured or predicted RMR (ml O2·kg−1·min−1 or kcal·kg−1·h−1) as a correction factor can appropriately adjust for individual differences when estimating the energy cost of moderate intensity walking (5.6 km/h).

The energy cost of household and garden activities in 55- to 65-year-old males

This study measured the energy expenditure of four self-paced household and garden tasks to determine whether 55- to 65-year-old men performed them at a moderate intensity [3-6 metabolic equivalents (METs)] and to predict the activity intensity via indirect methods. Resting metabolic rate and oxygen consumption were measured using Douglas bags in 50 men (X +/- SD: 60.6 +/-3.2 years, 175.8 +/- 5.6 cm, 82.6 +/- 10.1 kg ) who performed self-perceived moderate paced walking and self-paced sweeping, window cleaning, vacuuming and lawn mowing. Heart rate, CSA accelerometer counts (hip and arm), Quetelet's index, Borg rating of perceived exertion and respiratory frequency were measured as possible predictors of energy expenditure. Each of the four household and garden activities was performed at a mean intensity of > or = 3.0 METs in both the standardised laboratory environment (sweeping = 3.4, window cleaning = 3.8, vacuuming = 3.0 and lawn mowing = 5.3 METs) and the subjects' homes (sweeping = 4.1, window cleaning = 3.5, vacuuming = 3.6 and lawn mowing = 5.0 METs). Comparisons between the two settings were significantly different (p < or =0.008). Except for window cleaning, the MET values were not different from those of our previous younger sample (35-45 years). Regression analysis yielded prediction equations with 95% confidence intervals of +/-0.8 METs for both the laboratory and home environments. Although the energy expenditure means for these activities indicate that they can contribute to the 30 min day(-1) of moderate intensity physical activity required to confer health benefits, there was substantial inter-individual variability. While the regression equations lack predictive precision at the individual level, they were able to determine whether energy expenditure was above the 3.0 MET threshold with correct classification rates of 91% and 94% in the laboratory and home, respectively.