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  • 1.
    Borges, Joao Batista
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Bergman, Jakob S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Amato, Marcelo B. P.
    Avenel, Jacques
    Montmerle-Borgdorff, Stephanie
    First-time imaging of effects of inspired oxygen concentration on regional lung volumes and breathing pattern during hypergravity2015In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 115, no 2, p. 353-363Article in journal (Refereed)
    Abstract [en]

    Aeroatelectasis can develop in aircrew flying the latest generation high-performance aircraft. Causes alleged are relative hyperoxia, increased gravity in the head-to-foot direction (+G(z)), and compression of legs and stomach by anti-G trousers (AGT). We aimed to assess, in real time, the effects of hyperoxia, +G(z) accelerations and AGT inflation on changes in regional lung volumes and breathing pattern evaluated in an axial plane by electrical impedance tomography (EIT). The protocol mimicked a routine peacetime flight in combat aircraft. Eight subjects wearing AGT were studied in a human centrifuge during 1 h 15 min exposure of +1 to +3.5G(z). They performed this sequence three times, breathing AIR, 44.5 % O-2 or 100 % O-2. Continuous recording of functional EIT enabled uninterrupted assessment of regional lung volumes at the 5th intercostal level. Breathing pattern was also monitored. EIT data showed that +3.5G(z), compared with any moment without hypergravity, caused an abrupt decrease in regional tidal volume (V-T) and regional end-expiratory lung volume (EELV) measured in the EIT slice, independently of inspired oxygen concentration. Breathing AIR or 44.5 % O-2, sub-regional EELV measured in the EIT slice decreased similarly in dorsal and ventral regions, but sub-regional V-T measured in the EIT slice decreased significantly more dorsally than ventrally. Breathing 100 % O-2, EELV and V-T decreased similarly in both regions. Inspired tidal volume increased in hyperoxia, whereas breathing frequency increased in hypergravity and hyperoxia. Our findings suggest that hypergravity and AGT inflation cause airway closure and air trapping in gravity-dependent lung regions, facilitating absorption atelectasis formation, in particular during hyperoxia.

  • 2.
    Ekelund, Ulf
    et al.
    Örebro universitet, Institutionen för hälsovetenskap och medicin.
    Poortvliet, Eric
    Unit for Preventive Nutrition, Department of Medical Nutrition, Karolinska Institutet, Huddinge, Sweden.
    Nilsson, Andreas
    Örebro universitet, Institutionen för hälsovetenskap och medicin.
    Yngve, Agneta
    Unit for Preventive Nutrition, Department of Medical Nutrition, Karolinska Institutet, Huddinge, Sweden.
    Holmberg, Anders
    Department of Statistics, Örebro University, 701 82 Örebro, Sweden.
    Sjöström, Michael
    Department of Physical Education and Health, Örebro University, Örebro, Sweden; Unit for Preventive Nutrition, Department of Medical Nutrition, Karolinska Institutet, Huddinge, Sweden.
    Physical activity in relation to aerobic fitness and body fat in 14- to 15-year-old boys and girls2001In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 85, no 3-4, p. 195-201Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Ekelund, Ulf
    et al.
    Örebro universitet, Hälsovetenskapliga institutionen.
    Poortvliet, Eric
    Yngve, Agneta
    Hurtig-Wennlöf, Anita
    Örebro universitet, Institutionen för klinisk medicin.
    Nilsson, Andreas
    Örebro universitet, Hälsovetenskapliga institutionen.
    Sjöström, Michael
    Heart rate as an indicator of the intensity of physical activity in human adolescents2001In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 85, no 3-4, p. 244-249Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Hallman, David M.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences.
    Lindberg, Lars-Göran
    Arnetz, Bengt B.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Social Medicine.
    Lyskov, Eugene
    Effects of static contraction and cold stimulation on cardiovascular autonomic indices, trapezius blood flow and muscle activity in chronic neck-shoulder pain2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 8, p. 1725-1735Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to investigate reactions in trapezius muscle blood flow (MBF), muscle activity, heart rate variability (HRV) and systemic blood pressure (BP) to autonomic tests in subjects with chronic neck-shoulder pain and healthy controls. Changes in muscle activity and blood flow due to stress and unfavourable muscle loads are known underlying factors of work-related muscle pain. Aberration of the autonomic nervous system (ANS) is considered a possible mechanism. In the present study, participants (n = 23 Pain, n = 22 Control) performed autonomic tests which included a resting condition, static hand grip test (HGT) at 30% of maximal voluntary contraction, a cold pressor test (CPT) and a deep breathing test (DBT). HRV was analysed in time and frequency domains. MBF and muscle activity were recorded from the upper trapezius muscles using photoplethysmography and electromyography (EMG). The pain group showed reduced low frequency-HRV (LF) and SDNN during rest, as well as a blunted BP response and increased LF-HRV during HGT (a dagger systolic 22 mm Hg; a dagger LF(nu) 27%) compared with controls (a dagger systolic 27; a dagger LF(nu) 6%). Locally, the pain group had attenuated trapezius MBF in response to HGT (Pain 122% Control 140%) with elevated trapezius EMG following HGT and during CPT. In conclusion, only HGT showed differences between groups in systemic BP and HRV and alterations in local trapezius MBF and EMG in the pain group. Findings support the hypothesis of ANS involvement at systemic and local levels in chronic neck-shoulder pain.

  • 5. Henje-Blom, Eva
    et al.
    Olsson, Erik M. G.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Serlachius, Eva
    Ericson, Mats
    Ingvar, Martin
    Heart rate variability is related to self-reported physical activity in a healthy adolescent population2009In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 106, no 6, p. 877-883Article in journal (Refereed)
    Abstract [en]

    This study investigated whether there is a relationship between heart rate variability (HRV) versus lifestyle and risk factors for cardiovascular disease in a population of healthy adolescents. HRV is as an index of tonic autonomic activity and in adults HRV is related to lifestyle and risk factors for cardiovascular disease, but it is not known if this is the case in adolescents. HRV was registered for 4 min in sitting position in 99 healthy adolescents (age range 15 years 11 months-17 years 7 months) and repeated after 6 months. On both occasions there were significant correlations (P < 0.05) between physical activity and HRV, with respective r values: high frequency (HF) 0.26, 0.30; low frequency power (LF) 0.35, 0.29 and the standard deviation of inter-beat intervals (SDNN) 0.28, 0.37. There was no significant interaction between first and second measurements. In contrast, there were no correlations to sleeping patterns, eating habits and smoking. Risk factors for cardiovascular disease [body mass index (BMI = weight (kg)/length in m(2)), systolic blood pressure and p-glucose] did not show any repeatable significant correlations to HRV. Multiple regression models showed that physical activity was a predictor for HF, LF and SDNN in both measurements. In conclusion HF, LF and SDNN were reproducible after 6 months and were related to physical activity on both occasions.

  • 6. Nilsson, Johnny
    et al.
    Tinmark, Fredrik
    Halvorsen, Kjartan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Arndt, Anton
    Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 6, p. 1385-1394Article in journal (Refereed)
    Abstract [en]

    This study incorporated variations in speed and the horizontal resistance acting upon elite female skiers during double poling (DP) on a treadmill and specifically analyzed biomechanical adaptations to these variations. Whole body kinematics and pole force data were recorded and used to calculate the moment of force acting on the shoulder and elbow joints. Data were obtained with a 3D optoelectronic system using reflective markers at given anatomical landmarks. Forces along the long axis of the right pole were measured with a piezoelectric force transducer. Surface electrodes were used to record EMG activity in the rectus femoris, rectus abdominis, latissimus dorsi and triceps brachii muscles. In a first set of recordings, the participants double poled with zero elevation at five different speeds from 8 to 17 km h(-1). In a second set of recordings, horizontal resistance was added by weights (0.4-1.9 kg) attached to a pulley system pulling the skier posteriorly during DP at 14 km h(-1). Results showed increasing relative duration of the thrust phase with increasing resistance, but not with speed. Significant kinematic differences occurred with increase in both speed and resistance. The mean (+/- SD) horizontal force components ranged between 1.7 (+/- 1.3) and 2.8 (+/- 1.1) percent (%) bodyweight (BW) in the speed adaptation and 3.1 (+/- 0.6) and 4.0 (+/- 1.3) % BW in the adaptation to horizontal resistance. Peak muscle activity showed a central to peripheral (proximo-distal) activation sequence. The temporal cycle phase pattern in the adaptation to speed and horizontal resistance differed.

  • 7. Richter, H. O.
    et al.
    Zetterberg, Camilla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Occupational and Environmental Medicine. University of Gävle, Department of Occupational and Public Health Sciences, Centre for Musculoskeletal Research.
    Forsman, M.
    Trapezius muscle activity increases during near work activity regardless of accommodation/vergence demand level2015In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 115, no 7, p. 1501-1512Article in journal (Refereed)
    Abstract [en]

    To investigate if trapezius muscle activity increases over time during visually demanding near work. The vision task consisted of sustained focusing on a contrast-varying black and white Gabor grating. Sixty-six participants with a median age of 38 (range 19-47) fixated the grating from a distance of 65 cm (1.5 D) during four counterbalanced 7-min periods: binocularly through -3.5 D lenses, and monocularly through -3.5 D, 0 D and +3.5 D. Accommodation, heart rate variability and trapezius muscle activity were recorded in parallel. General estimating equation analyses showed that trapezius muscle activity increased significantly over time in all four lens conditions. A concurrent effect of accommodation response on trapezius muscle activity was observed with the minus lenses irrespective of whether incongruence between accommodation and convergence was present or not. Trapezius muscle activity increased significantly over time during the near work task. The increase in muscle activity over time may be caused by an increased need of mental effort and visual attention to maintain performance during the visual tasks to counteract mental fatigue.

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