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- Ekelund, Ulf, 1960-, et al.
(author)
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Heart rate as an indicator of the intensity of physical activity in human adolescents
- 2001
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In: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 85:3-4, s. 244-249
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Journal article (peer-reviewed)abstract
- The aims of this study were, in a group of adolescents, firstly to identify the absolute heart rates (HR) and the percentages of maximal heart rates (HRmax) corresponding to 40%, 60% and 80% of peak oxygen uptake (PVO2), secondly to identify absolute and relative (%PVO2) oxygen uptakes (VO2) corresponding to HR of 120, 140 and 160 beats.min-1, and thirdly to examine a possible effect of fatness and fitness on the relationship between HR and VO2. The subjects were 127 (60 boys, 67 girls) adolescents with a mean age of 14.8 (SD 0.3) years. The HR and VO2 were measured by means of an incremental exercise test to exhaustion. Linear regressions were performed for the HR-VO2 and VO2-HR relationships using absolute and relative (%HRmax, %PVO2) data for each individual. From these regressions, target HR and VO2 were computed. Average target HR corresponding to 40%, 60% and 80% of PVO2 were: 119 (SD 9), 145 (SD 9), 171 (SD 8), and 120 (SD 10), 146 (SD 8), 172 (SD 8) beats.min-1 for boys and girls, respectively. Average VO2 corresponding to HR of 120, 140 and 160 beats.min-1 were: 22 (SD 5), 30 (SD 5), 38 (SD 6) and 18 (SD 4), 24 (SD 4), 31 (SD 4) mlO2.kg-1.min-1 for boys and girls, respectively. An analysis of covariance showed a significant fitness effect (P < 0.001) for predicted VO2 at all HR studied. The results suggest that the use of absolute HR to define exercise intensity levels when assessing young people's physical activity using HR monitoring detracts from the validity of the interpretation of the data.
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| 2. |
- Ekelund, Ulf, 1960-, et al.
(author)
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Physical activity assessed by activity monitor and doubly labeled water in children
- 2001
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In: Medicine & Science in Sports & Exercise. - : Ovid Technologies (Wolters Kluwer Health). - 0195-9131 .- 1530-0315. ; 33:2, s. 275-281
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Journal article (peer-reviewed)abstract
- PURPOSE: To validate the Computer Science and Application's (CSA) activity monitor for assessment of the total amount of physical activity during two school-weeks in 9-yr-old children and to develop equations to predict total energy expenditure (TEE) and activity energy expenditure (AEE) from activity counts and anthropometric variables.METHODS: A total of 26 children (15 boys and 11 girls, mean age 9.1 +/- 0.3 yr) were monitored for 14 consecutive days. TEE was simultaneously measured by the doubly labeled water method. Averaged activity counts (counts.min(-1)) were compared with data on: 1) TEE, 2) AEE = TEE minus basal metabolic rate (BMR; estimated from predictive equations), and 3) daily physical activity level (PAL = TEE/BMR).RESULTS: Physical activity determined by activity counts was significantly related to the data on energy expenditures: TEE (r = 0.39; P < 0.05), AEE (r = 0.54; P < 0.01), and PAL (r = 0.58; P < 0.01). Multiple stepwise regression analysis showed that TEE was significantly influenced by gender, body composition (body weight or fat free mass), and activity counts (R(2) = 0.54--0.60). AEE was significantly influenced by activity counts and gender (R(2) = 0.45). There were no significant differences between activity counts and PAL in discriminating among activity levels with "low" (PAL < 1.56), "moderate" (1.57 < or = PAL > or = 1.81), and "high" (PAL > 1.81) intensity.CONCLUSION: Activity counts from the CSA activity monitor seems to be a useful measure of the total amount of physical activity in 9-yr-old children. Activity counts contributed significantly to the explained variation in TEE and was the best predictor of AEE.
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| 3. |
- Ekelund, Ulf, 1960-, et al.
(author)
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Physical activity in relation to aerobic fitness and body fat in 14- to 15-year-old boys and girls
- 2001
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In: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 85:3-4, s. 195-201
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Journal article (peer-reviewed)abstract
- The purpose of this study was to examine the strength of the relationship between different variables of physical activity and aerobic fitness and body fat in adolescent boys and girls. Activity energy expenditure (AEE), time spent in a sedentary state, and time spent engaged in moderate and vigorous physical activity (MVPA, > or = 50% peak oxygen uptake, VO2peak) were assessed by the minute-by-minute heart rate monitoring method in 82 randomly selected 14- to 15-year olds (42 boys, 40 girls). Body fat was determined by measuring skinfold thicknesses. VO2peak was measured by indirect calorimetry. Somatic maturity level was determined by percentages of adult (i.e. 18 years) height attained at examination. AEE was related to aerobic fitness for both genders (boys, r = 0.30, P = 0.056; girls, r = 0.45, P = 0.003). For boys, there was a significant relationship between maturity level and VO2peak (r = 0.48, P < 0.001). For both genders, body fat was significantly and negatively related to VO2peak (r = -0.48 and r = -0.43, P < 0.01). Body fat and maturity explained 47% of the variation in VO2peak in boys, whereas AEE and body fat explained 22% of the variation in VO2peak in girls. No significant associations between physical activity variables and the data on body fat were observed. The total amount of physical activity (AEE) was related to VO2peak, at least in adolescent girls. Although VO2peak seems to be influenced by the maturity level in adolescent boys, the data support the promotion of a daily active lifestyle among young people.
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| 4. |
- Ekelund, Ulf, 1960-, et al.
(author)
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Total daily energy expenditure and pattern of physical activity measured by minute-by-minute heart rate monitoring in 14-15 year old Swedish adolescents
- 2000
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In: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 54:3, s. 195-202
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To assess total daily energy expenditure (TDEE) and patterns of physical activity among Swedish male and female adolescents and to relate the amount and intensity of physical activity to existing recommendations (energy expenditure equal to or above 12.4 kJ/kg/day or accumulation of 30 min/day in moderate physical activity equal to 4.5 times sedentary energy expenditure or more).DESIGN: TDEE, physical activity level (PAL=TDEE/BMR), energy expenditure (EE) and time spent in different intensities of physical activity were assessed by using minute-by-minute heart rate monitoring in combination with laboratory measured sedentary energy expenditure (SEE) and peak oxygen uptake.SETTING: Department of Physical Education and Health, Orebro University, and Department of Clinical Physiology, Orebro Medical Centre Hospital, Sweden.SUBJECTS: Eighty-two 14-15 y old adolescents (42 boys, 40 girls) from the city of Orebro, randomly selected through a two-stage sampling procedure.RESULTS: TDEE was 12.8 MJ/day and 10.0 MJ/day for boys and girls respectively (P<0.001) and PAL was 1.74 and 1.67 (NS). Forty-four percent and 47%, respectively, of TDEE referred to EE in physical activity, of which 70% for both genders referred to light physical activity (corresponding to <4.5 times SEE). Eleven boys and 14 girls had an EE lower than 12.4 kJ/kg/day and/or did not accumulate 30 min/day in physical activity >/=4.5 SEE. Those (n=20) with the highest PAL values (>2.01 and 1.81, respectively) spent 149 min/day at a >/=4.5 SEE intensity level compared to 40 min/day for those (n=30) with the lowest PAL values (<1.55 and 1.45, respectively).CONCLUSIONS: Swedish adolescent boys and girls are similarly physically active. The major amount of time devoted to physical activity refers to light physical activity. At least thirty percent of adolescents seem not to achieve appropriate levels of physical activity considered to be beneficial for health.
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| 5. |
- Nilsson, Andreas, 1973-, et al.
(author)
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Assessing physical activity among children with accelerometers using different time sampling intervals and placements
- 2002
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In: Pediatric Exercise Science. - : Human Kinetics. - 0899-8493 .- 1543-2920. ; 14:1, s. 87-96
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Journal article (peer-reviewed)abstract
- The aim was to investigate (a) the effect of five different time sampling intervals (epoch settings) on different intensity levels when assessing physical activity with an accelerometer (CSA, WAM 7164), and (b) whether the placement of the monitor (on the hip and back) would affect the outcome. Sixteen children (aged 7 yrs) were monitored for four consecutive days. A significant main epoch effect was found for time spent at very high (p < 01) and high (p < 01) intensity activities. No significant difference between the two placements regarding total amount of physical activity (cnts times mm super (-1)) or different intensity levels was observed. In conclusion, different time sampling intervals, but not placement, should be carefully considered when assessing physical activity.
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| 9. |
- Sjöström, Michael, et al.
(author)
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Om barnens vardagliga aktivitet och gällande rekommendationer : European Youth Heart Study
- 2002
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In: Svensk Idrottsforskning. - 1103-4629. ; 11:3, s. 62-67
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Journal article (peer-reviewed)abstract
- Att mäta vardaglig fysisk aktivitet är svårt, särskilt när det gäller barn. Den idag mest tillförlitliga mätmetoden nyttjar rörelsemätare av typ accelerometer. Den tillåter bestämning av den totala aktiviteten för varje minut under en hel dag flera dagar/veckor i en följd. Dessutom kan man se hur aktiviteten är fördelad med avseende på dess intensitet. Vi har på detta sätt studerat tusen svenska skolbarn som en del av vår medverkan i European Youth Heart Study (EYHS). Det visar sig, när nu den fysiska aktiviteten för första gången har mätts på detta sätt, att barn och unga är mycket mer aktiva än vad många föreställer sig.
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| 10. |
- Yngve, Agneta, Professor, 1953-, et al.
(author)
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Effect of monitor placement and of activity setting on the MTI accelerometer output
- 2003
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In: Medicine & Science in Sports & Exercise. - 0195-9131 .- 1530-0315. ; 35:2, s. 320-326
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Journal article (peer-reviewed)abstract
- PURPOSE: To examine the effect of monitor placement (hip vs back) and of activity setting (treadmill vs track) on the output from the Manufacturing Technology Inc. (MTI), activity monitor (model WAM 7164).METHODS: In a laboratory study, 28 subjects (14 men, 14 women) walked at a normal pace, walked at a fast pace, and jogged at a comfortable pace on an indoor track. These activities were repeated on a treadmill using the individual speeds from the track locomotion. Oxygen uptake was measured simultaneously using a portable metabolic system. One activity monitor was worn on the hip and one on the lower back. In a field study, 34 subjects (18 men, 16 women) each wore two monitors (hip and low back placement) for seven consecutive days. In the laboratory study, ANOVA showed significant effects of placement ( P = 0.009) and setting ( P < 0.001), indicating that activity counts differ between different body sites and different settings (track vs treadmill). Gross energy expenditure predictive equations were developed and thereafter evaluated in the field study. Time spent at moderate and vigorous intensity of physical activity was 38% and 85% ( P < 0.001) higher when calculated from the treadmill-based equations as compared to the track-based equations. Free-living physical activity estimates were not affected by the placement.CONCLUSION: The relationship between activity counts and energy expenditure during laboratory locomotion is placement and setting-specific. When habitual physical activity is assessed in free-living subjects, the treadmill derived relationship between energy expenditure and activity counts may overestimate time spent at moderate intensity of physical activity, whereas the placement of the monitor does not influence on the interpretation of the data.
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