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- Bojsen-Møller, Emil, 1989-
(författare)
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Movement Behaviors and Cognitive Health for Office Workers
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The lifetime trajectories of movement behavior and cognitive functioning depend on complex interactions between genetic and environmental factors. There is substantial evidence suggesting that physical activity benefits cognitive functions. However, how sedentary behavior and the composition of movement behaviors (i.e., sleep, physical activity, and sedentary behavior) influences cognitive functions remains to be elucidated. Observational studies suggest that sedentary time is unfavorably related to cognitive functions in older adults, but the majority of evidence comes from self-reported estimates of movement behavior, which are rather weakly related to device-based measures. Furthermore, while evidence suggests that structured exercise can have protective effects on cognition in inactive older adults, much less is known about how midlife movement behavior is related to cognitive functions. Thus, knowledge of how midlife movement behavior relates to and possibly affects cognitive functions and its underlying mechanisms is much needed. This thesis is part of a larger research project investigating how movement behaviors relate to and influence cognitive function, mental health, and neurophysiological mechanisms underpinning these. The project specifically targets healthy office workers and is co-produced with employers of office workers and health-promoting companies. This thesis aimed to investigate how movement behaviors relate to and influence cognitive functions and neuroplasticity among office workers.The first study investigated cross-sectional relationships between device-measured movement behavior and cognitive functions among 334 office workers. The results revealed no association between total time spent in moderate to vigorous physical activity or sedentary behavior and cognitive functions, suggesting that this association may not be as robust as previously suggested in older populations or as inferred from self-report. The second study investigated the extent to which corticospinal excitability is influenced by different movement behaviors. Sixteen sedentary office workers participated in a cross-over randomized controlled trial. We contrasted 3 hours of prolonged sitting with 3 hours of interrupted sitting and 2.5 hours sitting followed by a 25-minute bout of exercise. Acute changes in corticospinal excitability and long-term potentiation-like neuroplasticity were investigated using transcranial magnetic stimulation and paired associative stimulation. Changes in corticospinal excitability over time did not differ between conditions, suggesting that in inactive middle-aged office workers, a physical activity bout or frequently breaking up prolonged sitting does not induce immediate changes in corticospinal excitability or long-term potentiation-like neuroplasticity. The third and fourth studies are based on a 6-month cluster-randomized intervention conducted in 263 healthy office workers. An ecological model for behavior change was used to design two interventions aiming at reducing sedentary behavior or increasing physical activity relative to a passive control group, with the ultimate aim of improving cognitive functions and mental health. The third study investigated how effective each intervention was at changing the 24-hour movement behavior, and the fourth study examined intervention effects on cognitive functions. The results showed that the interventions were ineffective in reducing sedentary behavior and increasing physical activity, respectively, with no detected beneficial effects on cardiorespiratory fitness or cognitive functions relative to the control group. Changes in cognition from baseline to follow-up were not associated with changes in the composition of movement behaviors or cardiorespiratory fitness, but some associations between changes in movement behaviors and cognition were moderated by sex, age, and cardiorespiratory fitness. Thus, the third and fourth studies of the thesis have highlighted the challenges involved in successfully achieving movement behavior change to address the possible effects on cognitive improvements in an ecological setting.In summary, the results presented in this thesis did not provide support for an association between movement behaviors and cognitive functions in healthy physically active office workers, demonstrated no acute effect of a single session of physical activity or breaking up prolonged sitting on corticospinal excitability in sedentary office workers, and revealed no evidence for successful movement behavior change or benefits for cognition in an ecological cluster-randomized intervention in healthy physically active office workers. The findings suggest that among physically active office workers, sedentary behavior may not be as detrimental for cognition and neuroplasticity as previously suggested and shows that changing movement behavior in office workers at the workplace represents a challenging endeavor. Still, these findings do not exclude the possibility that changes in movement behaviors might benefit cognitive functions in physically inactive office workers at higher cardiovascular risk, with lower cardiorespiratory fitness and/or lower daily cognitive stimulation.
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| 2. |
- Crommert, Martin Eriksson, 1974-
(författare)
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On the role of transversus abdominis in trunk motor control
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- All trunk muscles are important contributors to spine stability. However, the deepest abdominal muscle, transversus abdominis (TrA), with its characteristically horizontal fibre orientation seems to serve a unique function in trunk motor control. The main mechanical role of TrA is believed to be to contribute to vertebral alignment during imposed moments on the trunk, executed mainly via either regulating the pressure level within the abdominal cavity and/or transmit forces to the spine via the thoracolumbar fascia. However, the complete function of TrA and what factors affect its activation are still not fully understood. The purpose of the present thesis was to investigate the role of TrA in trunk motor control, specifically in relation to the presence or absence of postural demand on the trunk.The timing and magnitude of TrA activation were investigated, in relation to other trunk muscles, with intramuscular fine-wire electrodes in different loading situations and body positions with varying postural demand.In a side-lying position, with no postural demand of keeping the trunk upright, the activation of TrA was delayed relative the superficial abdominal muscles compared to previous experiments performed in a standing position. The timing and magnitude of activation of TrA did not depend upon the direction of perturbation. In the standing position, different static arm positions revealed that the activation of TrA co-varied with variations in the degree of postural demand on the trunk and also the imposed moments, regardless of moment direction. Finally, a study on rapid arm flexion movements confirmed that TrA is part of the pre-programmed anticipatory response in advance of known perturbations. The activation magnitude of TrA was the same regardless if the arm movement induced flexion or extension moments on the trunk.In conclusion, the activation of TrA is associated with the upright postural demand on the trunk and with balancing imposed moments acting on the spine, regardless their direction. The findings are in support of the beliefs that TrA act as a general, direction non specific, stabilizer of the lumbar spine.
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