Background/Objective: This study investigated the validity of the Actiheart device for estimating free-living physical activity energy expenditure (PAEE) in adolescents. Subjects/Methods: Total energy expenditure (TEE) was measured in eighteen Canadian adolescents, aged 15–18 years, by DLW. Physical activity energy expenditure was calculated as 0.9 X TEE minus resting energy expenditure, assuming 10% for the thermic effect of feeding. Participants wore the chest mounted Actiheart device which records simultaneously minute-by-minute acceleration (ACC) and heart rate (HR). Using both children and adult branched equation modeling, derived from laboratory-based activity, PAEE was estimated from the ACC and HR data. Linear regression analyses examined the association between PAEE derived from the Actiheart and DLW method where DLW PAEE served as the dependent variable. Measurement of agreement between the two methods was analyzed using the Bland-Altman procedure. Results: A nonsignificant association was found between the children derived Actiheart and DLW PAEE values (R = .23, R2 = .05, p = .36); whereas a significant association was found between the adult derived Actiheart and DLW PAEE values (R = .53, R2 = .29, p < .05). Both the children and adult equation models lead to overestimations of PAEE by the Actiheart compared with the DLW method, by a mean difference of 31.42 kcal·kg−·d−1 (95% limits of agreement: −45.70 to −17.15 kcal·kg−1·d−1 and 9.80 kcal·kg−1·d−1 (95% limits of agreement: −21.22-1.72 kcal·kg−1·d−1), respectively. Conclusion: There is relatively poor measurement of agreement between the Actiheart and DLW for assessing free-living PAEE in adolescents. Future work should develop group based branched equation models specifically for adolescents to improve the utility of the device in this population.
Nerissa Campbell, Harry Prapavessis, Casey Gray, Erin McGowan, Elaine Rush and Ralph Maddison
Melody Oliver, Philip J. Schluter, Genevieve N. Healy, El-Shadan Tautolo, Grant Schofield and Elaine Rush
Breaks in sedentary behavior are associated with reduced body size in general populations. This study is the first to consider the relationship between objectively assessed sedentary breaks and body size in Pacific children and their mothers.
Pacific children aged 6 years (n = 393) and their mothers (n = 386) residing in New Zealand were invited to participate in 2006. Sedentary time was assessed via accelerometry. Average frequency, duration, and intensity of breaks in sedentary time per hour were calculated. Waist circumference was assessed and demographic factors collected via questionnaire. Relationships between waist circumference and potential associated factors for participants were assessed using linear regression analyses.
Accelerometer data were obtained from 126 children (52 boys) and 108 mothers. Mean (standard deviation) waist circumference values for mothers and children were 114 cm (20.1 cm) and 59.4 cm (7.8 cm), respectively. For mothers, time spent sedentary and being an ex/nonsmoker were positively related to waist circumference. For children, watching television every day and having a mother with a high waist circumference was associated with a greater waist circumference.
Strategies that focus on reducing sedentary time in Pacific mothers and on encouraging television free days in young Pacific children are recommended.
Andrea J. Braakhuis, Will G. Hopkins, Timothy E. Lowe and Elaine C. Rush
A quantitative food-frequency questionnaire (FFQ) was developed to determine antioxidant intake in athletes. The questionnaire will be valuable for researchers wishing to standardize antioxidant intake or simply document habitual intake during an intervention trial. One hundred thirteen athletes participated in the validity study, of whom 96 completed the questionnaire and blood test, 81 completed the 7-d food diary and questionnaire, and 63 completed the 7-d food diary and blood test. Validity was investigated by comparing total and food-group antioxidant intakes from the questionnaire with those from a subsequent 7-d food diary. Measures of construct validity were determined by comparing a biomarker of antioxidant capacity (ferric-reducing ability of plasma) in a blood sample with antioxidant intakes from the questionnaire and diary. The correlation between the diary and questionnaire energy-adjusted estimates of total antioxidant intake was modest (.38; 90% confidence limits, ± .14); the correlation was highest for antioxidants from cereals (.55; ± .11), which contributed the greatest proportion (31%) of the total antioxidant intake. Correlations were also high for coffee and tea (.51; ± .15) and moderate for vegetables (.34; ± .16) and fruit (.31; ± .16). The correlation of the plasma biomarker with the questionnaire estimate was small (.28; ± .15), but the correlation with the diary estimate was inconsequential (–.03; ± .15). One-week test–retest reliability of the questionnaire’s estimates of antioxidant intake in 20 participants was high (.83; ± .16). In conclusion, the FFQ is less labor intensive for participants and researchers than a 7-d diary and appears to be at least as trustworthy for estimating antioxidant intake.
Nerissa Campbell, Anca Gaston, Casey Gray, Elaine Rush, Ralph Maddison and Harry Prapavessis
Accurate assessment of physical activity energy expenditure (PAEE) among adolescents is important for surveillance, evaluating interventions, and understanding the relation between energy balance and normal physiological and behavioral growth and development. The purpose of this study was to examine the validity of the Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH)13 for measuring PAEE among adolescents.
The participants were seventeen adolescents (9 females; Mean age = 17.53; SD = 0.62). Energy expenditure was measured during a 9-day period with doubly labeled water (DLW). The SQUASH was self-administered on the morning of the 10th day and assessed commuting activities, leisure time activities, household activities, and activities at work and school over the previous 9 days.
A Bland-Altman plot indicated that the SQUASH underestimated PAEE compared with DLW by a mean difference of 126 kcal·d−1 (95% limits of agreement: –1,207 to 1,459 kcal·d−1), representative of a 10% underestimation. The Spearman rank order correlation coefficient showed there was a significant association between the SQUASH and DLW (r = .50, P = .04), for estimating PAEE.
When using a sample of highly active adolescents, the SQUASH is a valid self-report tool for measuring PAEE at the group and individual rank order level.