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| 23. |
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| 24. |
- Brage, Søren, et al.
(författare)
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Hierarchy of individual calibration levels for heart rate and accelerometry to measure physical activity.
- 2007
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Ingår i: J Appl Physiol. - : American Physiological Society. - 8750-7587. ; 103:2, s. 682-92
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Tidskriftsartikel (refereegranskat)abstract
- Combining accelerometry with heart rate (HR) monitoring may improve precision of physical activity measurement. Considerable variation exists in the relationships between physical activity intensity (PAI) and HR and accelerometry, which may be reduced by individual calibration. However, individual calibration limits feasibility of these techniques in population studies, and less burdensome, yet valid, methods of calibration are required. We aimed to evaluate the precision of different individual calibration procedures against a reference calibration procedure: a ramped treadmill walking-running test with continuous measurement of PAI by indirect calorimetry in 26 women and 25 men [mean (SD): 35 ( 9 ) yr, 1.69 (0.10) m, 70 ( 14 ) kg]. Acceleration (along the longitudinal axis of the trunk) and HR were measured simultaneously. Alternative calibration procedures included treadmill testing without calorimetry, submaximal step and walk tests with and without calorimetry, and nonexercise calibration using sleeping HR and gender. Reference accelerometry and HR models explained >95% of the between-individual variance in PAI ( P < 0.001). This fraction dropped to 73 and 81%, respectively, for accelerometry and HR models calibrated with treadmill tests without calorimetry. Step-test calibration captured 62–64% (accelerometry) and 68% (HR) of the variance between individuals. Corresponding values were 63–76% and 59–61% for walk-test calibration. There was only little benefit of including calorimetry during step and walk calibration for HR models. Nonexercise calibration procedures explained 54% (accelerometry) and 30% (HR) of the between-individual variance. In conclusion, a substantial proportion of the between-individual variance in relationships between PAI, accelerometry, and HR is captured with simple calibration procedures, feasible for use in epidemiological studies.
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| 25. |
- Brooke, Hannah L, et al.
(författare)
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Changes in time-segment specific physical activity between ages 10 and 14 years : A longitudinal observational study.
- 2016
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Ingår i: Journal of Science and Medicine in Sport. - : Elsevier BV. - 1440-2440 .- 1878-1861. ; 19:1, s. 29-34
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Describe (1) time-segment specific changes in physical activity (PA) into adolescence, (2) differences in change in PA between specific time-segments (weekdays-weekends, in-school-out-of-school, out-of-school-weekends, lesson-time-lunch-time), and (3) associations of change in time-segment specific with overall PA.DESIGN: Longitudinal observational study (4-year follow-up).METHODS: Children from the SPEEDY study (n=769, 42% boys) had PA measured by accelerometer for at least three days at ages 10.2±0.3, 11.2±0.3 and 14.3±0.3years. Changes in moderate-to-vigorous PA (ΔMVPA, minutes ≥2000counts/minute [cpm]) and total PA (ΔTPA, average cpm) during weekdays, weekends, in-school, out-of-school, lesson-times and lunch-times, were tested using three level (age, individual, school) mixed-effects linear regression. Differences in ΔMVPA/ΔTPA between time-segments were tested using time-segment×age interaction terms. Associations of four-year time-segment specific ΔMVPA/ΔTPA with four-year overall ΔMVPA/ΔTPA were tested using two level (time-segment specific ΔMVPA/ΔTPA, school) mixed-effects linear regression.RESULTS: MVPA and TPA declined in all time-segments, except lesson-time MVPA. Annual ΔMVPA and, for boys only, ΔTPA was greater on weekends than weekdays (beta±SE for interaction term: boys, -3.53±0.83min, -29.64±7.64cpm; girls, -2.20±0.64min) and out-of-school (boys, -4.36±0.79min, -19.36±8.46cpm; girls, -2.44±0.63min). ΔMVPA and ΔTPA during lunch-time was greater than during lesson-time (boys, -0.96±0.20min, -36.43±6.55cpm; girls, -0.90±0.13min, -38.72±4.40cpm). ΔTPA was greater out-of-school than in-school (boys, -19.89±6.71cpm; girls, -18.46±6.51cpm). For all time-segments, four-year ΔMVPA/ΔTPA was positively associated with four-year overall ΔMVPA/ΔTPA (all p<0.042), except for girl's in-school and lunch-time TPA.CONCLUSIONS: Interventions focused on PA maintenance could target all time-segments, but weekends and out-of-school may be particularly advantageous due to the relatively large declines observed.
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| 26. |
- Brooke, Hannah L, et al.
(författare)
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More of the same or a change of scenery : an observational study of variety and frequency of physical activity in British children.
- 2013
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Physical activity is important for children's health, but successful physical activity promotion is challenging. Whether performing many different types of activities (Variety) is associated with higher physical activity independent of the number of activity sessions (Frequency) is unknown, but this information could inform physical activity promotion and public health strategies in children.METHODS: In the SPEEDY study we measured moderate-to-vigorous intensity physical activity (MVPA; ≥2000 counts/minute) over 7 days using GT1M Actigraph accelerometers in 1700 children from Norfolk, UK (56% girls, Mean ± SD 10.3 ± 0.3 years-old). Children reported participation in 28 leisure-time activities over the previous 7 days. Sex differences in activity participation were assessed using multilevel logistic regression, clustered by school. Associations of log-transformed MVPA with z-score-Variety (number of different activities/week) and z-score-Frequency (sum of all activity sessions/week) were examined using multilevel linear regression, adjusted for age, sex, parental education and age-standardised BMI.RESULTS: Children's activity participation often reflected gender stereotypes. Mean ± SD Variety was 10.8 ± 5.0 activities/week, and Frequency was 24.2±15.0 sessions/week. In separate models lnMVPA had similar strength, positive associations with z-score-Variety and z-score-Frequency (Exp β(95% CI); Variety 1.04(1.02-1.06), Frequency 1.04(1.02-1.06)). lnMVPA was not associated with z-score-Variety independent of z-score-Frequency (Variety 1.01(0.98-1.04), Frequency 1.03(1.00-1.06)).CONCLUSIONS: Future physical activity interventions and public health strategies could allow for gender specific activity preferences and could target both Variety and Frequency of activities participated in by children.
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| 27. |
- Carlsson, Marcus, et al.
(författare)
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Center of volume and total heart volume variation in healthy subjects and patients before and after coronary bypass surgery.
- 2005
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 25:4, s. 226-233
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Total heart volume variation (THVV) and center of volume variation (COVV) likely affects the efficiency of cardiac pumping, but no study has determined COVV of the heart throughout the cardiac cycle or the effect of surgery on THVV in adults. Therefore, the purposes of this study were to determine COVV in healthy adults and patients with cardiac failure due to ischemic heart disease (IHD), identify any difference in THVV between these two groups, and determine how these parameters are affected by coronary bypass surgery. METHODS: Six healthy volunteers and eight patients before and after surgery were investigated with cardiovascular magnetic resonance imaging. The atrioventricular plane movement (AVPM), THVV and time resolved three-dimensional coordinates of the center of the cardiac volume (COVV) were measured. RESULTS: COVV followed a loop in 3D space that between the end-points was approximately 2 mm with no difference between healthy subjects and patients before surgery (P = 0.093), although AVPM was significantly lower in patients (P = 0.002). However, after surgery the COVV during the cardiac cycle doubled (P = 0.012) and the increase in THVV was significant (P = 0.050), although of very small magnitude, and the AVPM remained unchanged (P = 0.401). CONCLUSION: COVV and THVV were similar in patients and healthy subjects even though AVPM was lower in the patient population. After surgery, however, COVV doubled despite a very small change in THVV and no change in AVPM. Taken together, the results of this study may provide new insights into the energy expenditure and efficiency of cardiac pumping.
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| 28. |
- Carlsson, Marcus, et al.
(författare)
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Heart filling exceeds emptying during late ventricular systole in patients with systolic heart failure and healthy subjects – a cardiac MRI study
- 2019
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 39:3, s. 192-200
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Tidskriftsartikel (refereegranskat)abstract
- Background: Total heart volume (THV) within the pericardium is not constant throughout the cardiac cycle and THV would intuitively be lowest at end systole. We have, however, observed a phase shift between ventricular outflow and atrial inflow which causes the minimum THV to occur before end systole. The aims were to explain the mechanism of the late-systolic net inflow to the heart and determine whether this net inflow is affected by increased cardiac output or systolic heart failure. Methods and Results: Healthy controls (n = 21) and patients with EF<35% (n = 14) underwent magnetic resonance imaging with flow measurements in vessels to and from the heart, and this was repeated in nine controls during 140 μgram kg−1 min−1 adenosine infusion. Minimum THV occurred 78 ± 6 ms before end of systolic ejection (8 ± 1% of the cardiac cycle) in controls. The late-systolic net inflow was 12·3 ± 1·1 ml or 6·0 ± 0·5% of total stroke volume (TSV). Cardiac output increased 66 ± 8% during adenosine but late-systolic net inflow to the heart did not change (P = 0·73). In patients with heart failure, late-systolic net inflow of the heart′s left side was lower (3·4 ± 0·5%) compared to healthy subjects (5·3 ± 0·6%, P = 0·03). Conclusions: Heart size increases before end systole due to a late-systolic net inflow which is unaffected by increased cardiac output. This may be explained by inertia of blood that flows into the atria generated by ventricular systole. The lower late-systolic net inflow in patients with systolic heart failure may be a measure of decreased ventricular filling due to decreased systolic function, thus linking systolic to diastolic dysfunction.
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| 29. |
- Carlsson, Marcus, et al.
(författare)
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Submaximal adenosine-induced coronary hyperaemia with 12 h caffeine abstinence: implications for clinical adenosine perfusion imaging tests.
- 2015
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 35:1, s. 49-56
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Tidskriftsartikel (refereegranskat)abstract
- Adenosine is widely used as a vasodilator agent in myocardial perfusion imaging. Caffeine inhibits the effect, but the time of caffeine abstinence needed is under discussion and varies from 12 to 24 h. Therefore, our aim was to examine whether the time of caffeine abstinence affects the hyperaemic response using quantification of coronary sinus flow (CS F) with cardiac magnetic resonance (CMR) during adenosine infusion.
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| 30. |
- Cedercrantz-Borna, Catharina, et al.
(författare)
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High-sensitivity troponin T as a diagnostic tool for acute coronary syndrome in the real world: an observational study.
- 2014
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Ingår i: European Journal of Emergency Medicine. - 0969-9546. ; 21:3, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The 2011 European Society of Cardiology guidelines state that acute coronary syndrome (ACS) may be excluded with a rapid 3 h high-sensitivity troponin T (HsTnT) sampling protocol. We aimed to evaluate the diagnostic and prognostic performance of HsTnT in patients with chest pain admitted with possible ACS in routine care. METHODS: A total of 773 consecutive patients admitted for in-hospital care for chest pain suspicious of ACS were included retrospectively. HsTnT values at admission and at 3-4 and 6-7 h were analysed for diagnostic performance. In addition, prognostic performance towards a combined 60-day endpoint of ACS, nonelective revascularization or death of all causes was studied. RESULTS: Twenty-three per cent of the patients had ACS during the hospital stay and 1.6% had an endpoint after discharge but within 60 days. The sensitivity of HsTnT for ACS at admission, 3-4 and 6-7 h was only 68, 79 and 81%, respectively. Sensitivity and negative predictive value for acute myocardial infarction alone were 80 and 93% on admission and 97 and 99% at 3-4 h. Among patients aged 75 years and older, 63% had a positive HsTnT on admission, but only 39% of these had an ACS during hospital stay. CONCLUSION: Our data confirm that prolonged testing with HsTnT after 3-4 h does not improve diagnostic performance for ACS. However, although sensitivity for acute myocardial infarction was very good, sensitivity for ACS was insufficient to rule out ACS even at 6-7 h. Less than half of all recorded positive HsTnT were true positives. On the basis of these results, we find it unlikely that HsTnT has improved the diagnosis of ACS in the emergency care setting.
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