Physical Activity Patterns of People Affected by Depressive and Anxiety Disorders as Measured by Accelerometers: A Cross-Sectional Study

Background

Exercise can relieve both depressive and anxiety disorders and it is therefore of importance to establish movement patterns of mildly to moderately affected sufferers to estimate the treatment potential. The aim is to describe the physical activity patterns of people affected by mild to moderate depressive and/or anxiety symptoms using objective measures of physical activity.

Methods

The design of the study was cross-sectional using data from 165 people aged 18–65 years, with mild to moderate depressive and/or anxiety disorder symptoms (scoring ≥10 on the PHQ-9). Diagnoses were made using Mini International Neuropsychiatric Interview (MINI) and symptom severity was measured with the Montgomery-Åsberg Depression Rating Scale (MADRS). The participants wore accelerometers for a week to evaluate physical activity patterns.

Results

No statistically significant differences were detected between different diagnoses, though depressed participants tended to be less active and more sedentary. Only one-fifth of the sample followed public health guidelines regarding physical activity. Each one point increase in MADRS was associated with a 2.4 minute reduction in light physical activity, independent of moderate-to-vigorous physical activity and sedentary time. MADRS was positively associated with number of sedentary bouts.

Conclusions

The physical activity pattern of people with depressive and/or anxiety disorders was characterized by large amounts of sedentary time and low fulfillment of physical activity guidelines. There is therefore a large treatment potential for this group by increasing exercise. The results suggest that instead of focusing exclusively on high intensity exercise for treating depressive and anxiety disorders, health care providers might encourage patients to reduce sedentary time by increasing light physical activity and decreasing the number of sedentary bouts, though further studies are needed that can determine directionality.     

Reliability and Validity of the Transport and Physical Activity Questionnaire (TPAQ) for Assessing Physical Activity Behaviour

Background

No current validated survey instrument allows a comprehensive assessment of both physical activity and travel behaviours for use in interdisciplinary research on walking and cycling. This study reports on the test-retest reliability and validity of physical activity measures in the transport and physical activity questionnaire (TPAQ).

Methods

The TPAQ assesses time spent in different domains of physical activity and using different modes of transport for five journey purposes. Test-retest reliability of eight physical activity summary variables was assessed using intra-class correlation coefficients (ICC) and Kappa scores for continuous and categorical variables respectively. In a separate study, the validity of three survey-reported physical activity summary variables was assessed by computing Spearman correlation coefficients using accelerometer-derived reference measures. The Bland-Altman technique was used to determine the absolute validity of survey-reported time spent in moderate-to-vigorous physical activity (MVPA).

Results

In the reliability study, ICC for time spent in different domains of physical activity ranged from fair to substantial for walking for transport (ICC = 0.59), cycling for transport (ICC = 0.61), walking for recreation (ICC = 0.48), cycling for recreation (ICC = 0.35), moderate leisure-time physical activity (ICC = 0.47), vigorous leisure-time physical activity (ICC = 0.63), and total physical activity (ICC = 0.56). The proportion of participants estimated to meet physical activity guidelines showed acceptable reliability (k = 0.60). In the validity study, comparison of survey-reported and accelerometer-derived time spent in physical activity showed strong agreement for vigorous physical activity (r = 0.72, p<0.001), fair but non-significant agreement for moderate physical activity (r = 0.24, p = 0.09) and fair agreement for MVPA (r = 0.27, p = 0.05). Bland-Altman analysis showed a mean overestimation of MVPA of 87.6 min/week (p = 0.02) (95% limits of agreement −447.1 to +622.3 min/week).

Conclusion

The TPAQ provides a more comprehensive assessment of physical activity and travel behaviours and may be suitable for wider use. Its physical activity summary measures have comparable reliability and validity to those of similar existing questionnaires.     

Predictive Validity and Classification Accuracy of ActiGraph Energy Expenditure Equations and Cut-Points in Young Children

Objectives

Evaluate the predictive validity of ActiGraph energy expenditure equations and the classification accuracy of physical activity intensity cut-points in preschoolers.

Methods

Forty children aged 4–6 years (5.3±1.0 years) completed a ∼150-min room calorimeter protocol involving age-appropriate sedentary, light and moderate-to vigorous-intensity physical activities. Children wore an ActiGraph GT3X on the right mid-axillary line of the hip. Energy expenditure measured by room calorimetry and physical activity intensity classified using direct observation were the criterion methods. Energy expenditure was predicted using Pate and Puyau equations. Physical activity intensity was classified using Evenson, Sirard, Van Cauwenberghe, Pate, Puyau, and Reilly, ActiGraph cut-points.

Results

The Pate equation significantly overestimated VO₂ during sedentary behaviors, light physical activities and total VO₂ (P<0.001). No difference was found between measured and predicted VO₂ during moderate-to vigorous-intensity physical activities (P = 0.072). The Puyau equation significantly underestimated activity energy expenditure during moderate-to vigorous-intensity physical activities, light-intensity physical activities and total activity energy expenditure (P<0.0125). However, no overestimation of activity energy expenditure during sedentary behavior was found. The Evenson cut-point demonstrated significantly higher accuracy for classifying sedentary behaviors and light-intensity physical activities than others. Classification accuracy for moderate-to vigorous-intensity physical activities was significantly higher for Pate than others.

Conclusion

Available ActiGraph equations do not provide accurate estimates of energy expenditure across physical activity intensities in preschoolers. Cut-points of ≤25counts⋅15 s⁻¹ and ≥420 counts⋅15 s⁻¹ for classifying sedentary behaviors and moderate-to vigorous-intensity physical activities, respectively, are recommended.     

Screening Physical Activity in Family Practice: Validity of the Spanish Version of a Brief Physical Activity Questionnaire

Objectives

The use of brief screening tools to identify inactive patients is essential to improve the efficiency of primary care-based physical activity (PA) programs. However, the current employment of short PA questionnaires within the Spanish primary care pathway is unclear. This study evaluated the validity of the Spanish version of a Brief Physical Activity Assessment Tool (SBPAAT).

Methods

A validation study was carried out within the EVIDENT project. A convenience sample of patients (n = 1,184; age 58.9±13.7 years; 60.5% female) completed the SBPAAT and the 7-day Physical Activity Recall (7DPAR) and, in addition, wore an accelerometer (ActiGraph GT3X) for seven consecutive days. Validity was evaluated by measuring agreement, Kappa correlation coefficients, sensitivity and specificity in achieving current PA recommendations with the 7DPAR. Pearson correlation coefficients with the number of daily minutes engaged in moderate and vigorous intensity PA according to the accelerometer were also assessed. Comparison with accelerometer counts, daily minutes engaged in sedentary, light, moderate, and vigorous intensity PA, total daily kilocalories, and total PA and leisure time expenditure (METs-hour-week) between the sufficiently and insufficiently active groups identified by SBPAAT were reported.

Results

The SBPAAT identified 41.3% sufficiently active (n = 489) and 58.7% insufficiently active (n = 695) patients; it showed moderate validity (k = 0.454, 95% CI: 0.402–0.505) and a specificity and sensitivity of 74.3% and 74.6%, respectively. Validity was fair for identifying daily minutes engaged in moderate (r = 0.215, 95% CI:0.156 to 0.272) and vigorous PA (r = 0.282, 95% CI:0.165 to 0.391). Insufficiently active patients according to the SBPAAT significantly reported fewer counts/minute (-22%), fewer minutes/day of moderate (-11.38) and vigorous PA (-2.69), spent fewer total kilocalories/day (-753), and reported a lower energy cost (METs-hour-week) of physical activities globally (-26.82) and during leisure time (-19.62).

Conclusions

The SBPAAT is a valid tool to identify Spanish-speaking patients who are insufficiently active to achieve health benefits.     

Objectively Measured Intensity of Physical Activity and Adiposity in Middle‐Aged Women

Objective: The aim of this study was to evaluate the relationship between objectively measured physical activity (ACT), particularly intensity of physical activity (iACT), and body fat percentage (BF%) in 278 middle‐aged women. Secondary purposes were to ascertain the association between physical activity duration (dACT) and BF% and the extent to which potentially confounding factors, including total ACT, energy intake, body weight, and season of assessment, influenced the relationship between iACT and BF%. Research Methods and Procedures: A cross‐sectional design was used. Subjects were apparently healthy, 35 to 45 years old, premenopausal, nonsmokers, with BMIs < 30 kg/m². Approximately 90 percent were white, 81% were married, and 37% were college graduates. ACT was assessed using Computer Science and Application accelerometers worn for 7 consecutive days. The accelerometers recorded movement continuously, and activity counts were collapsed into 10‐minute epochs. Intensity was indexed using seven activity count cut‐off points, and duration was based on the number of 10‐minute epochs at each intensity level. BF% was assessed using multiple measurements in the Bod Pod. Energy intake was measured using 7‐day weighed diet records during the same week subjects wore the accelerometers. Results: BF% was strongly and inversely associated with iACT and dACT. Controlling for energy intake and body weight strengthened the relationships among iACT, dACT, and BF%. Control of total ACT weakened the association. Discussion: Engaging in higher intensity and/or longer duration ACT is associated with lower BF% compared with lower intensity and/or shorter durations of activity.     

Open reading frame sequencing and structure-based alignment of polypeptides encoded by RT1-Bb, RT1-Ba, RT1-Db, and RT1-Da alleles

MHC class II genes are major genetic components in rats developing autoimmunity. The majority of rat MHC class II sequencing has focused on exon 2, which forms the first external domain. Sequence of the complete open reading frame for rat MHC class II haplotypes and structure-based alignment is lacking. Herein, the complete open reading frame for RT1-B, RT1-B, RT1-D, and RT1-D was sequenced from ten different rat strains, covering eight serological haplotypes, namely a, b, c, d, k, l, n, and u. Each serological haplotype was unique at the nucleotide level of the sequenced RT1-B/D region. Within individual genes, the number of alleles identified was seven, seven, six, and three and the degree of amino-acid polymorphism between allotypes for each gene was 22%, 16%, 19%, and 0.4% for RT1-B, RT1-B, RT1-D, and RT1-D, respectively. The extent and distribution of amino-acid polymorphism was comparable with mouse and human MHC class II. Structure-based alignment identified the 65–66 deletion, the 84a insertion, the 9a insertion, and the 1a–1c insertion in RT1-B previously described for H2-A. Rat allele-specific deletions were found at RT1-B76 and RT1-D90–92. The mature RT1-D polypeptide was one amino acid longer than HLA-DRB1 due to the position of the predicted signal peptide cleavage site. These data are important to a comprehensive understanding of MHC class II structure-function and for mechanistic studies of rat models of autoimmunity.Nucleotide sequence data reported are available in the GenBank database under the accession numbers AY626180–AY626189 for all RT1-Bb sequences, AY626190–AY626199 for all RT1-Ba sequences, AY626200-AY626209 for all RT1-Db sequences and AY626210–AY626219 for all RT1-Da sequences.     

Physical activity-related energy expenditure with the RT3 and TriTrac accelerometers in overweight adults

Objective: The objective was to evaluate two accelerometers, the RT3 and the TriTrac‐R3D for their ability to produce estimates of physical activity‐related energy expenditure (PAEE) in overweight/obese adults. Research Methods and Procedures: PAEE estimates from both accelerometers were obtained in two experiments. In Experiment 1, 13 overweight/obese subjects (BMI 34.2 ± 6.4 kg/m²) were monitored over 2 weeks in everyday life, PAEE being simultaneously measured by the doubly labeled water method (DLW). In Experiment 2, 8 overweight/obese subjects (BMI 34.3 ± 5.0 kg/m²) and 10 normal‐weight subjects (BMI 20.8 ± 2.1 kg/m²) were monitored during a treadmill walking protocol, PAEE being simultaneously measured by indirect calorimetry. Results: In Experiment 1, there was no significant difference between methods in mean PAEE (DLW: 704 ± 223 kcal/d, RT3: 656 ± 140 kcal/d, TriTrac‐R3D 624 ± 419 kcal/d). The relative difference between methods (accelerometer vs. DLW) was ?17.1% ± 16.7% for the RT3 and ?20.0 ± 44.6% for the TriTrac‐R3D. Correlation for PAEE between RT3 and DLW was higher than between TriTrac‐R3D and DLW (r = 0.67, p < 0.05 and r = 0.36, p = 0.25, respectively). The 95% confidence interval (CI) (kcal/d) of the mean difference between methods was large, amounting to ?385 to 145 for the RT3 and ?887 to 590 for the TriTrac‐R3D. In Experiment 2, both accelerometers were sensitive to the changes in treadmill speed, with no significant difference in mean PAEE between methods in overweight/obese subjects. Conclusions: Although both accelerometers did not provide accurate estimates of PAEE at individual levels, the data suggest that RT3 has the potential to assess PAEE at group levels in overweight/obese subjects.     

Validity of Global Physical and Emotional SUDS

Despite the wide-spread use of Subjective Units of Discomfort Scales, or SUDS, to measure anxiety to specific stimuli, little information has been published on the validity of such scales and even less on their use as global measures of emotional and physical discomfort. Data was examined for 182 consecutive admissions to a psychology clinic to determine the relationship of self-rating of emotional and physical discomfort to one another and of the emotional self-rating to the clinician rating of general functioning (GAF). As expected, patients’ ratings of their emotional discomfort were significantly higher than ratings of their physical discomfort (t = 9.077, p < .001). Emotional SUDS were significantly and negatively related to clinicians’ GAF ratings (r = − 0.439, p < .001), indicating that the two ratings measured related global constructs. Data for the 53 patients who also completed the MMPI-2 was drawn from the larger sample to determine the nature of the relationship between SUDS and two measures of general emotional distress, with patients’ SUDS significantly related to both the A scale (r = 0.351, p < .05) and the neurotic index (r = 0.366, p < .01). Finally, there was a significant decrease in the emotional SUDS (t = 4.686, p < .001) but not the physical SUDS (t = 0.788, p = .434) after 3 months of psychotherapy. The data supports SUDS as global measures of both physical and emotional discomfort.     

Differential Response of Lymphocytes and Neutrophils to High Intensity Physical Activity and to Vitamin C Diet Supplementation

We have determined the effects of chronic vitamin C intake on neutrophil and lymphocyte antioxidant defences during the acute phase immune response induced by intense exercise. Blood samples were taken from 16 voluntary athletes in basal conditions, both immediately after and 1 h after a duathlon competition. Sportsmen's nutrient intakes were determined before the competition. After determining the basal plasmatic ascorbate levels, the results were analysed taking into account the vitamin C intake and their plasmatic levels. Two groups were constituted, the vitamin C supplemented group and the control group, with the dietary vitamin C intake as the only statistical difference between groups. The duathlon competition induced a significant neutrophilia, which was higher in the supplemented group. Lymphocyte antioxidant enzyme activities increased after the competition, with a higher increase in SOD activity in the control group than in the supplemented one. The competition decreased neutrophil antioxidant enzyme activities and neutrophil ascorbate concentration. The decrease in the SOD activity in the supplemented group was higher than in the control group. Finally, the duathlon competition increased the expression of MAC-1 neutrophil adhesion molecule in the supplemented group. High vitamin C intake influenced the response of neutrophils and lymphocytes to oxidative stress induced by exercise, increasing the neutrophil activation.     

Reliability and Validity of the Self- and Interviewer-Administered Versions of the Global Physical Activity Questionnaire (GPAQ)

Objective

The Global Physical Activity Questionnaire (GPAQ) was originally designed to be interviewer-administered by the World Health Organization in assessing physical activity. The main aim of this study was to compare the psychometric properties of a self-administered GPAQ with the original interviewer-administered approach. Additionally, this study explored whether using different accelerometry-based physical activity bout definitions might affect the questionnaire’s validity.

Methods

A total of 110 participants were recruited and randomly allocated to an interviewer- (n = 56) or a self-administered (n = 54) group for test-retest reliability, of which 108 participants who met the wear time criteria were included in the validity study. Reliability was assessed by administration of questionnaires twice with a one-week interval. Criterion validity was assessed by comparing against seven-day accelerometer measures. Two definitions for accelerometry-data scoring were employed: (1) total-min of activity, and (2) 10-min bout.

Results

Participants had similar baseline characteristics in both administration groups and no significant difference was found between the two formats in terms of validity (correlations between the GPAQ and accelerometer). For validity, the GPAQ demonstrated fair-to-moderate correlations for moderate-to-vigorous physical activity (MVPA) for self-administration (r _s = 0.30) and interviewer-administration (r _s = 0.46). Findings were similar when considering 10-min activity bouts in the accelerometer analysis for MVPA (r _s = 0.29 vs. 0.42 for self vs. interviewer). Within each mode of administration, the strongest correlations were observed for vigorous-intensity activity. However, Bland-Altman plots illustrated bias toward overestimation for higher levels of MVPA, vigorous- and moderate-intensity activities, and underestimation for lower levels of these measures. Reliability for MVPA revealed moderate correlations (r _s = 0.61 vs. 0.63 for self vs. interviewer).

Conclusions

Our findings showed comparability between both self- and interviewer-administration modes of the GPAQ. The GPAQ in general but especially the self-administered version may offer a relatively inexpensive method for measuring physical activity of various types and at different domains. However, there may be bias in the GPAQ measurements depending on the overall physical activity. It is advisable to incorporate accelerometers in future studies, particularly when measuring different intensities of physical activity.     

Leisure Time Physical Activity of Moderate to Vigorous Intensity and Mortality: A Large Pooled Cohort Analysis

Background

Leisure time physical activity reduces the risk of premature mortality, but the years of life expectancy gained at different levels remains unclear. Our objective was to determine the years of life gained after age 40 associated with various levels of physical activity, both overall and according to body mass index (BMI) groups, in a large pooled analysis.

Methods and Findings

We examined the association of leisure time physical activity with mortality during follow-up in pooled data from six prospective cohort studies in the National Cancer Institute Cohort Consortium, comprising 654,827 individuals, 21–90 y of age. Physical activity was categorized by metabolic equivalent hours per week (MET-h/wk). Life expectancies and years of life gained/lost were calculated using direct adjusted survival curves (for participants 40+ years of age), with 95% confidence intervals (CIs) derived by bootstrap. The study includes a median 10 y of follow-up and 82,465 deaths. A physical activity level of 0.1–3.74 MET-h/wk, equivalent to brisk walking for up to 75 min/wk, was associated with a gain of 1.8 (95% CI: 1.6–2.0) y in life expectancy relative to no leisure time activity (0 MET-h/wk). Higher levels of physical activity were associated with greater gains in life expectancy, with a gain of 4.5 (95% CI: 4.3–4.7) y at the highest level (22.5+ MET-h/wk, equivalent to brisk walking for 450+ min/wk). Substantial gains were also observed in each BMI group. In joint analyses, being active (7.5+ MET-h/wk) and normal weight (BMI 18.5–24.9) was associated with a gain of 7.2 (95% CI: 6.5–7.9) y of life compared to being inactive (0 MET-h/wk) and obese (BMI 35.0+). A limitation was that physical activity and BMI were ascertained by self report.

Conclusions

More leisure time physical activity was associated with longer life expectancy across a range of activity levels and BMI groups. Please see later in the article for the Editors'' Summary     

Validity and Calibration of the Youth Activity Profile

Purpose

The purpose of this study was to calibrate and cross-validate the Youth Activity Profile (YAP), a self-report tool designed to capture physical activity (PA) and sedentary behaviors (SB) in youth.

Methods

Eight schools in the Midwest part of the U.S. were involved and a total of 291 participants from grades 4–12 agreed to wear an accelerometer (SWA Armband) and complete the YAP in two separate weeks (5–7 days apart). Individual YAP items capture PA behavior during specific segments of the week and these items were combined with temporally matched estimates of moderate-to-vigorous PA (MVPA) and sedentary time from the SWA to enable calibration. Quantile regression procedures yielded YAP prediction algorithms that estimated MVPA at School, MVPA at Out-of-School, MVPA on Weekend, as well as time spent in SB. The YAP estimates of time spent in MVPA and SB were cross-validated using Pearson product correlations and limits of agreement, as indicative of individual error and, equivalence testing techniques as indicative of group-level error.

Result

Following calibration, the correlations between YAP and SWA estimates of MVPA were low to moderate (r_range = .19 to .58) and individual-level YAP estimates of MVPA ranged from -134.9% to +110.0% of SWA MVPA values. Differences between aggregated YAP and SWA MVPA ranged from -3.4 to 21.7 minutes of MVPA at the group-level and predicted YAP MVPA estimates were within 15%, 20%, and 30%, of values from the SWA for the School, Out-of-School, and Weekend time periods, respectively. Estimates of time spent in SB were highly correlated with each other (r = .75). The individual estimates of SB ranged from -54.0% to +44.0% of SWA sedentary time, and the aggregated group-level estimates differed by 49.7 minutes (within 10% of the SWA aggregated estimates).

Conclusions

This study provides preliminary evidence that the calibration procedures enabled the YAP to provide estimates of MVPA and SB that approximated values from an objective monitor. The YAP provides a simple, low-cost and educationally sound method to accurately estimate children’s MVPA and SB at the group level.     

Two‐Year Changes in Child Weight Status,Diet, and Activity by Neighborhood Nutrition and Physical Activity Environment

Objective

The aim of this study was to examine 2‐year changes in weight status and behaviors among children living in neighborhoods differing on nutrition and activity environments.

Methods

A prospective observational study, the Neighborhood Impact on Kids study, was conducted in King County, Washington, and San Diego County, California. Children 6 to 12 years old and a parent or caregiver completed Time 1 (n = 681) and Time 2 (n = 618) assessments. Children lived in neighborhoods characterized as “high/favorable” or “low/unfavorable” in nutrition and activity environments, respectively (four neighborhood types). Child BMI z score and overweight or obesity status were primary outcomes, with diet and activity behaviors as behavioral outcomes.

Results

After adjusting for sociodemographics and Time 1 values, children living in two of the three less environmentally supportive neighborhoods had significantly less favorable BMI z score changes (+0.11, 95% CI: 0.01‐0.21; + 0.12, 95% CI: 0.03‐0.21), and all three less supportive neighborhoods had higher overweight or obesity (relative risks, 1.41‐1.49; 95% CI: 1.13‐1.80) compared with children in the most environmentally supportive neighborhoods. Changes in daily energy intake and sedentary behavior by neighborhood type were consistent with observed weight status changes, with unexpected findings for physical activity.

Conclusions

More walkable and recreation‐supportive environments with better nutrition access were associated with better child weight outcomes and related behavior changes.     

Effect of Exercise Intensity on Spontaneous Physical Activity Energy Expenditure in Overweight Boys: A Crossover Study

Objective

Evaluate the effect of different exercise intensities on spontaneous physical activity energy expenditure in overweight adolescents.

Methods

A crossover study was developed with a control session, followed by moderate and vigorous exercise sessions, with six days of monitoring each. Twenty-four adolescents, 11–13 years old, male and overweight were selected. Spontaneous physical activity energy expenditure was assessed by accelerometers. Linear mixed effects models were used to evaluate the differences per session across time.

Results

Energy expenditure during the 1st hour was different between all three sessions, with averages of 82, 286 and 343 kcal to the control, moderate and vigorous sessions, respectively (p <0.001). The same pattern of difference in energy expenditure between the sessions remained after 24 hours (704 vs 970 vs 1056 kcal, p <0.001). However, energy expenditure during the six days indicates compensation from second to the sixth day, although small differences remained at the end of the 6-day period (5102 vs 5193 vs 5271 kcal, p <0.001).

Conclusions

A single aerobic session seems to modify the spontaneous physical activities in overweight adolescents but still keeping the vigorous session with higher total energy expenditure during the follow-up period. Despite the observed compensatory effect, the greater energy expenditure observed in both moderate and vigorous exercise sessions indicates that physical activity should be recommended to promote an increased energy expenditure in adolescents.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT 02272088","term_id":"NCT02272088"}}NCT 02272088     

Validation of Cut-Points for Evaluating the Intensity of Physical Activity with Accelerometry-Based Mean Amplitude Deviation (MAD)

Purpose

Our recent study of three accelerometer brands in various ambulatory activities showed that the mean amplitude deviation (MAD) of the resultant acceleration signal performed best in separating different intensity levels and provided excellent agreement between the three devices. The objective of this study was to derive a regression model that estimates oxygen consumption (VO2) from MAD values and validate the MAD-based cut-points for light, moderate and vigorous locomotion against VO₂ within a wide range of speeds.

Methods

29 participants performed a pace-conducted non-stop test on a 200 m long indoor track. The initial speed was 0.6 m/s and it was increased by 0.4 m/s every 2.5 minutes until volitional exhaustion. The participants could freely decide whether they preferred to walk or run. During the test they carried a hip-mounted tri-axial accelerometer and mobile metabolic analyzer. The MAD was calculated from the raw acceleration data and compared to directly measured incident VO₂. Cut-point between light and moderate activity was set to 3.0 metabolic equivalent (MET, 1 MET = 3.5 ml · kg^-1 · min^-1) and between moderate and vigorous activity to 6.0 MET as per standard use.

Results

The MAD and VO₂ showed a very strong association. Within individuals, the range of r values was from 0.927 to 0.991 providing the mean r = 0.969. The optimal MAD cut-point for 3.0 MET was 91 mg (milligravity) and 414 mg for 6.0 MET.

Conclusion

The present study showed that the MAD is a valid method in terms of the VO₂ within a wide range of ambulatory activities from slow walking to fast running. Being a device-independent trait, the MAD facilitates directly comparable, accurate results on the intensity of physical activity with all accelerometers providing tri-axial raw data.     

γ‐Glutamyltransferase,Obesity, Physical Activity,and the Metabolic Syndrome in Indigenous Australian Adults

The aim of this study is to examine the association between obesity, metabolic syndrome, physical activity, and elevated γ‐glutamyltransferase (GGT) among Indigenous Australian adults who did not drink alcohol. A cross‐sectional study of 791 Indigenous adults in rural North Queensland communities was conducted between 1999 and 2001. Measures included serum GGT, fasting glucose, cholesterol, and triglycerides; resting blood pressure, BMI, and waist circumference; and self‐reported physical activity, alcohol intake, and tobacco smoking. Central obesity measured by waist circumference in this population was significantly associated with elevated GGT independently of lifestyle behaviors (Adjusted odds ratio (OR) = 2.7, 95% confidence interval (CI): 1.2–6.0). Metabolic syndrome (International Diabetes Federation definition) was also strongly associated with increased GGT (OR = 2.6, 95% CI: 1.5–4.6). Habitual physical activity may be slightly protective (OR = 0.9, 95% CI: 0.5–1.6) in this group, but this was not clearly demonstrated in this study. Prevention of type 2 diabetes and cardiovascular disease in this population should emphasize “waist loss” and metabolic health through dietary and other interventions.