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  • 1.
    Marklund, Sarah
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Sörlin, Ann
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Stenlund, Tobias
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Nyberg, Andre
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    To act or not to act - a sense of control is important for people with chronic obstructive pulmonary disease to increase physical activity: grounded theory study2023In: JMIR Formative Research, E-ISSN 2561-326X, Vol. 7, article id e39969Article in journal (Refereed)
    Abstract [en]

    Background: Among people with chronic obstructive pulmonary disease (COPD), low level of daily physical activity (PA) is the main risk factor for developing cardiovascular, metabolic, and musculoskeletal comorbidities. Increasing PA in people with COPD is complex as PA behavior itself is complex and multifaceted, including personal, physiological, and psychologicalelements as well as social and environmental factors. Although eHealth solutions such as web-based support or websites haveshown positive effects on PA in people with COPD, the results are inconclusive, and it is still unclear how eHealth solutionsmight be used to support positive changes in PA behavior in people with COPD.

    Objective: This study aimed to explore the perceptions of increasing objective PA when using a web-based eHealth tool amongpeople with COPD.

    Methods: This study was part of a pragmatic randomized controlled trial with in-depth interviews between the 3- and 12-month follow-ups. The methodology used was constructivist grounded theory. All sampling included participants from the randomized controlled trial intervention group, that is, participants who had access to the eHealth tool in question and agreed to be contacted for an in-depth interview. Inclusion of participants continued until data saturation was reached, resulting in an inclusion of 14 (n=8, 57% women) participants aged between 49 and 84 years and living in 8 municipalities in Middle and Northern Sweden. Two interviews were conducted face-to-face, and the remaining interviews were conducted via telephone. All interviews were recorded using a Dictaphone.

    Results: The analysis resulted in 3 main categories: welcoming or not welcoming action, having or lacking resources, and lowering the threshold. The first 2 categories contain barriers and facilitators, whereas the third category contains only facilitators. The categories lead to the more latent theme Perceiving enough control to enable action, meaning that it seems that perceiving the right amount of control is essential to maintain or increase the level of PA when using an eHealth tool, among patients with COPD. However, the right amount of control seemed to depend on the individual (and context) in question.

    Conclusions: The core category indicates that a need for a certain sense of control was interpreted as necessary for increasing the PA level as well as for using an eHealth tool to help increase the PA level. The eHealth tool seemed to strengthen or weaken the perception of control by either providing support or by being too demanding on the user. Perceptions varied depending onother environmental factors. The Fogg Behavior Model illustrated how motivational levels, ability levels, and functional triggers interact within our findings. Thus, this study provides further evidence for the importance of empowering the patients to boost their level of agency and their ability to improve PA levels.

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  • 2.
    Nyberg, Andre
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Lundell, Sara
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy. Umeå University, Faculty of Social Sciences, Department of Sociology.
    Stenlund, Tobias
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Marklund, Sarah
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    KOLwebben ökar kunskapen hos både personer med KOL och personal2023In: Fysioterapi, ISSN 1653-5804, no 1, p. 30-35Article, review/survey (Other (popular science, discussion, etc.))
    Abstract [sv]

    I ett försök att minska gapet mellan rådande riktlinjer gällande icke-farmakologiska interventioner och den vård som erbjuds till personer med KOL har vi, tillsammans med användare, utvecklat och utvärderat KOLwebben. Användning av KOLwebben ledde till en kliniskt relevant ökad fysisk aktivitetsnivå och en ökad kunskap om egenvårdsstrategier hos personer med KOL. Hälso- och sjukvårdspersonal i regional primärvård och kommunal hemsjukvård rapporterade ökad kunskap om sjukdomen, behandlingsmetoder, arbetssätt och att verktyget är ett stöd i deras arbete. Initialt krävs dock extra resurser i form av tid och rutiner för att implementering ska ske. Ett digitalt stöd som KOLwebben kan rekommenderas till personer som är motiverade till att använda e-hälsoverktyg och som har en tillräcklig förmåga att ta till sig information om sin hälsa.

  • 3.
    Rehn, Börje
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Stenlund, Tobias
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Lindroos, Ola
    Lundström, Ronnie
    Analysis of seated postures using orientation sensors2012Conference paper (Refereed)
  • 4.
    Stenlund, Tobias
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Seated postural reactions to mechanical shocks: laboratory studies with relevance for risk assessment and prevention of musculoskeletal disorders among drivers2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Professional drivers of off-road vehicles, driving on irregular terrain such as in forestry, agriculture and mining, are exposed to whole-body vibration and mechanical shocks. These driver groups have reported severe musculoskeletal problems in the spine, but the association to seated postural reactions is not fully understood. One assumption is that unexpected shocks may create excessive load on spinal joints. The driver’s posture and exposure to mechanical shocks are required to be included in work risk assessments, but muscle activity and body kinematics are not included. The overall aim of this thesis was to describe and analyse seated postural reactions to mechanical shocks and to evaluate measuring of seated postures with relevance for risk assessment and the prevention of musculoskeletal disorders among drivers.

    The thesis includes four studies, all laboratory-based using a repeated-measures design. Postural reactions were recorded from 23 (Paper I) and 20 (Paper II & III) young, healthy male participants who were seated on a movable platform. The platform delivered mechanical shocks with peak accelerations up to 14 m/s2 in lateral directions during different conditions. Furthermore, twenty participants (Paper IV) were tested by four testers for analysis of test-retest reliability within and between testers measuring seated postures. Kinematics were here detected by means of a motion analysis system (MoLabTM) and described for the spine as angular displacements or range of motion (ROM) using a three-segment model of neck, trunk and pelvis (Paper I–III) and as a more specific model (Paper IV). Surface electromyography (EMG) was recorded bilaterally on the following muscles; trapezius upper part, upper neck, erector spinae and external oblique (Paper I–III).

    The general findings show that EMG amplitudes normalised to maximum voluntary contractions (MVC) did not exceed 2% in the trapezius, 8% in the upper neck and erector spinae and 18% in the external oblique. The EMG amplitudes and the angular displacements in the neck were significantly reduced from the first compared to the fifth mechanical shock. Adding a cognitive task significantly increased angular displacements. The largest ROM with approximately 20° in each segment was found during a double-sided mechanical shock (shock that changes direction). The reliability within one tester measuring seated postures was mostly considered good and superior to the reliability between several testers, but still insensitive to changes of less than 10°.

    Exposure to single-sided or double-sided mechanical shocks with accelerations up to 14 m/s2 seem not to cause postural reactions to such an extent that overload of muscles or joint structures should be expected. There seems to be a quick adaptation that causes an improved readiness. The external obliques were most active when restoring equilibrium and seem important for stabilising the whole spinal column. Stability training, in order to improve neuromuscular control of the external obliques could, therefore, be a possible recommendation. The angular displacement in the neck increases if the subject solves a cognitive task of why such activities should be avoided when driving in difficult terrains. Since accurate descriptions of the spinal posture seems difficult even when advanced technical equipment is used, simpler models seem more appropriate. The results show that postural control is maintained even when exposed to considerable mechanical shocks. On the basis of these results, there is no need to change established risk assessment models.

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  • 5.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Burström, Lage
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Neely, Gregory
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Seated postural neck and trunk reactions to sideways perturbations with or without a cognitive task2015In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 25, no 3, p. 548-556Article in journal (Refereed)
    Abstract [en]

    Driving on irregular terrain will expose the driver to sideways mechanical shocks or perturbations that may cause musculoskeletal problems. How a cognitive task, imposed on the driver, affects seated postural reactions during perturbations is unknown. The aim of the present study was to investigate seated postural reactions in the neck and trunk among healthy adults exposed to sideways perturbations with or without a cognitive task. Twenty-three healthy male subjects aged 19-36 years, were seated on a chair mounted on a motion system and randomly exposed to 20 sideways perturbations (at two peak accelerations 5.1 or 13.2 m/s2) in two conditions: counting backwards or not. Kinematics were recorded for upper body segments using inertial measurement units attached to the body and electromyography (EMG) was recorded for four muscles bilaterally in the neck and trunk. Angular displacements (head, neck, trunk and pelvis) in the frontal plane, and EMG amplitude (normalised to maximum voluntary contractions, MVC) were analysed. The cognitive task provoked significantly larger angular displacements of the head, neck and trunk and significantly increased EMG mean amplitudes in the upper neck during deceleration, although 10% of MVC was never exceeded. A cognitive task seems to affect musculoskeletal reactions when exposed to sideways perturbations in a seated position.

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  • 6.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lindroos, Ola
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Seated postural loads caused by shock-type whole-body vibration when driving over obstacles2020In: International Journal of Forest Engineering, ISSN 1494-2119, E-ISSN 1913-2220, Vol. 31, no 3, p. 184-191Article in journal (Refereed)
    Abstract [en]

    Operators of mobile machines within forestry work long hours in seated postures while being exposed to whole-body vibration (WBV) that is associated with pain in the lower back and neck. Still, little is known about the contribution from postural loads. In this study postural loads and shock-type WBV exposure on drivers operating a forwarder during terrain-like conditions was measured and quantified using inertial measurement units (IMUs). Five male drivers drove a forwarder repeatedly over standardized steel obstacles using a predefined speed and posture followed by driving over natural obstacles along a terrain course using a self-selected speed and posture. IMUs were affixed along the spine, on the back of the head of the driver and on the seat to detect orientation, velocity, and acceleration. The result shows that the methodology for measuring WBV and postural load with IMUs is feasible. Postural loads, expressed as range of motions (ROMs), when driving over a single standardized obstacle at a speed of 3.3 km/h were up to 21 degrees in the neck segments. Increasing vehicle speed and size of obstacles increased postural loads. The terrain course resulted in higher ROMs in all body segments compared to a standardized obstacle, a difference in sideway seat acceleration but no differences regarding angular velocities of the head. Mechanical shocks at the seat were prevalent but the action limit value was exceeded only for one driver. Postural loads remained small during all conditions indicating that the spine can remain stable during exposure to shock-type WBV of this nature.

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  • 7.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Nyberg, Andre
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Lundell, Sara
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Web-based support for self-management strategies versus usual care for people with COPD in primary healthcare: a protocol for a randomised, 12-month, parallel-group pragmatic trial2019In: BMJ Open, E-ISSN 2044-6055, Vol. 9, no 10, article id e030788Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: The use of adequate self-management strategies for people with chronic obstructive pulmonary disease (COPD) may increase the level of physical activity (PA), improve health-related quality of life (HRQoL) and reduce healthcare use. Whether web-based support in addition to prompts (email and SMS) could be used to promote self-management strategies to facilitate behaviour change in people with COPD is not clear. This clinical trial aims to generate evidence on the effect of a web-based solution, the COPD Web, in a cohort of people with COPD in a primary healthcare context.

    METHODS AND ANALYSIS: The overall design is a pragmatic randomised controlled trial with preassessments and postassessments (3 and 12 months) and an implementation and user experience evaluation. People with a diagnosis of COPD, treated in primary healthcare will be eligible for the study. A total of 144 participants will be enrolled by healthcare professionals at included primary healthcare units and, after fulfilled baseline assessments, randomised to either control or intervention group. All participants will receive usual care, a pedometer and a leaflet about the importance of PA. Participants in the intervention will, in addition, get access to the COPD Web, an interactive self-managed website that aims to support people with COPD in self-management strategies. They will also continuously get support from prompts with a focus on behaviour change.The effect on participants' PA, dyspnoea, COPD-related symptoms, HRQoL and health economics will be assessed using accelerometer and questionnaires. To identify enablers and barriers for the use of web-based support to change behaviour, semistructured interviews will be conducted in a subgroup of participants at the 3 months follow-up.

    ETHICS AND DISSEMINATION: Ethical approval has been received from the Regional Ethical Review Board in Umeå, Sweden. Dnr 2018-274-31. Findings will be presented at conferences, submitted for publication in peer-reviewed journals and presented to the involved healthcare professionals, participants and patient organisations.

    TRIAL REGISTRATION NUMBER: NCT03746873.

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  • 8.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Lindroos, Ola
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Assessing postural load among drivers exposed to shock-type whole-body vibration using inertial measurements units: Results from measurements on standardized courses2019Conference paper (Refereed)
    Abstract [en]

    Background: Lower back and neck pain is common among persons who drive vehicles in their profession. The vehicle occupants are exposed to whole-body vibration (WBV) that may include mechanical shocks which are believed to increase the likelihood of injury further. Mechanical shocks are especially generated when driving on rough terrain and may challenge drivers' postural equilibrium. Little is known about the contribution of postural load to injury risk and thus objective measurements are necessary.

    Purpose: The purpose of the study was to assess the feasibility of registering and analyzing seated postural load and shock-type WBV synchronously using inertial measurement units (IMUs) among drivers of forest machines during terrain-like conditions.

    Methods: Five male participants (18-34 years old) drove a forest machine 6 times over three different standardized steal obstacles along a gravel course using a predefined speed and posture. Participants then drove the same vehicle 3 times over natural obstacles along a terrain course using a self-selected speed and posture. Three IMUs were affixed along the spine (at S2, Th2 and C4) and one to the head of participants as well as one to the seat. Data from the IMUs regarding accelerations and orientation in sagittal, frontal and horizontal plane were then analyzed.

    Results: Postural load, expressed as the range of motions (ROMs) in the upper neck, lower neck, trunk and pelvis were less than 22° in all directions during maneuvers on the standardized course. The size of obstacle and the vehicle speed had significant effects on the ROMs. No significant differences between courses were evident regarding seat accelerations and angular velocities at the drivers head. The WBV analysis of the terrain course indicated that mechanical shocks were prevalent but exceeded the exposure action value for only one driver and not the exposure limit value according to health and safety requirements within the European Union (EU directive 2002/44/EC).

    Conclusion(s): IMUs may objectively be used to register and present seated postural load and shock-type WBV exposure synchronously when driving on terrain. There seems to be a low risk of injuries from mechanical shocks since the magnitude of postural load (ROMs) during tested conditions was not considered to increase injury risk even though vehicle speed and the size of obstacles had a significant effect.

    Implications: Postural load when driving a forest machine during terrain-like conditions appears low in this study but more long-term field measurements on more drivers are needed before definite conclusions can be made. IMUs are regarded as promising tools for registering and representing seated postural load and shock-type WBV exposure. Future development could provide drivers with feedback regarding potentially injurious postures and/or high shock-type WBV exposure.

  • 9.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lindroos, Ola
    Institutionen för skogens biomaterial och teknologi (SBT), Sveriges lantbruksuniversitet, Umeå.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Neely, Gregory
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Adaptation of postural reactions in seated positions and influence of head posture when exposed to a single sideway perturbation: relevance for driving on irregular terrain2016In: Journal of Novel Physiotherapy and Physical Rehabilitation, ISSN 2455-5487, Vol. 3, no 1, p. 022-029Article in journal (Refereed)
    Abstract [en]

     Background and objectives: Mechanical perturbations in seated positions caused by driving on irregular terrain destabilize the driver which, combined with the drivers’ posture, may cause musculoskeletal disorders. The aim of this study was to investigate adaptation and the effect of different head postures on seated postural reactions caused by perturbations. 

    Materials and Methods: Twenty healthy male participants, aged 18-43 years, were tested on a movable platform delivering 15 sideways perturbations (peak acceleration 13.3 m/s2) while the participants held their head in a neutral or a laterally flexed posture. Surface electromyography (EMG) signals were recorded bilaterally in upper neck, trapezius, erector spinae and external oblique, while kinematics were recorded with inertial sensors for the head, trunk and pelvis. EMG amplitudes, muscle onset latencies and angular displacements in the frontal plane were analyzed. 

    Results: In the neutral position, the EMG amplitudes and neck angular displacements significantly decreased by 0.2% and more than 1.6° respectively after repeated perturbations. Muscle onset latencies remained unchanged. During lateral flexion of the head, the EMG amplitudes decreased by 0.5% but the muscular onset latencies increased by more than 9 ms. 

    Conclusion: The developed neuromuscular strategy seem to prefer a reduced EMG amplitude. The modest size of the postural reactions during the conditions presented here do not by themselves explain the musculoskeletal disorders found in drivers.

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  • 10.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lindroos, Ola
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Neely, Gregory
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Double-sided Mechanical Shocks Provoke Larger Seated Postural Reactions Compared to Single-Sided Mechanical Shocks2018In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 43, no 8, p. E482-E487Article in journal (Refereed)
    Abstract [en]

    STUDY DESIGN: Human volunteers were exposed experimentally to single-sided mechanical shocks (SSMS) and double-sided mechanical shocks (DSMS) while seated.

    OBJECTIVE: To describe and contrast seated postural reactions due to SSMS or DSMS in healthy male adults.

    SUMMARY OF BACKGROUND DATA: Mechanical shocks to the body, caused when driving on irregular terrain, are suggested to be hazardous to the spine and may be associated with the reported musculoskeletal pain of the back and neck among professional drivers. However, very little is known about the characteristics of seated postural reactions and the biomechanical effects caused by mechanical shocks.

    METHODS: Twenty healthy male subjects (18-43 years old) were exposed while seated to 5 SSMS and 15 DSMS in lateral directions. The second acceleration in the DSMS was in the opposite direction to the first acceleration and was either fast, medium or slow depending on the speed of direction change. Surface electromyography (EMG) was recorded in muscles of the upper neck, trapezius, erector spinae and external oblique while kinematics were recorded with inertial sensors placed at the neck, trunk and pelvis. Muscle activity was normalized to maximum voluntary contractions (MVC).

    RESULTS: The EMG amplitudes were significantly higher (0.6-1%; p < 0.001) for the fast DSMS compared to all other shocks. Range of motion (ROM) of the neck and trunk was greater during the DSMS compared to the SSMS. Evoked muscle activity was less than 2% MVC in the trapezius, less than 10% MVC in the erector spinae and upper neck while the activity exceeded 10% MVC in the external oblique muscles.

    CONCLUSION: Fast DSMS in lateral directions appear more demanding compared to SSMS, demonstrating augmented seated postural reactions. However, the present mechanical shocks employed did not seem to induce postural reactions with regard to ROM or muscle activity of a magnitude likely to cause musculoskeletal overload.

    LEVEL OF EVIDENCE: 4.

  • 11.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lindroos, Ola
    Institutionen för skogens biomaterial och teknologi (SBT), Sveriges lantbruksuniversitet, Umeå.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Neely, Gregory
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Greater seated postural reactions are provoked by double-sided compared to single-sided mechanical shocksManuscript (preprint) (Other academic)
    Abstract [en]

    Study design: Human volunteers were exposed experimentally to single-sided mechanical shocks (SSMS) and double-sided mechanical shocks (DSMS) while seated.

    Objective: To describe seated postural reactions due to SSMS and DSMS in healthy male adults.

    Summary of Background Data: Mechanical shocks, caused when driving on irregular terrain are suggested to be hazardous to the spine and may be associated with the reported musculoskeletal disorders of the back and neck among professional drivers.

    Methods: Twenty healthy male subjects (18-43 years old) were exposed while seated to 5 SSMS and 15 DSMS in lateral directions. The second acceleration in the DSMS was in the opposite direction to the first acceleration and divided into fast, medium and slow depending on the speed of direction change. Surface electromyography (EMG) was recorded in upper neck, trapezius, erector spinae and external oblique and kinematics were recorded with inertial sensors for the neck, trunk and pelvis. Muscle activity evoked by the shocks was normalized to maximum voluntary contractions (MVC).

    Results: The EMG amplitudes were significantly higher (0.6-1%; p<0.001) for the fast DSMS compared to all other shocks. Range of motions of the neck and trunk were greater from the DSMS compared to the SSMS. Muscle activity in the erector spinae and upper neck was sparse while the most intense muscle activity was found in the external obliques > 10% MVC, with elements of co-contraction.

    Conclusion: Fast DSMS in lateral directions appear more demanding compared to SSMS and increase seated postural reactions, especially activity in the external oblique muscles. Still, the extent of range of motions in the neck and trunk and muscle activities alone, do not suggest a high risk for musculoskeletal overload.

  • 12.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lindroos, Ola
    Dept. of Forest Biomaterials & Technology, Swedish University of Agricultural Sciences, Sweden.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Inter- and intra-tester reliability when measuring seated spinal postures with inertial sensors2014In: International Journal of Industrial Ergonomics, ISSN 0169-8141, E-ISSN 1872-8219, Vol. 44, no 5, p. 732-738Article in journal (Refereed)
    Abstract [en]

    Prolonged awkward sitting postures may be associated with neck or back pain, but it is often unclear which specific postures cause most problems and which mechanisms that may underlie the pain. In order to increase the knowledge in this field, it seems crucial first of all to be able to analyse, in depth, different seated spinal postures. A problem is however the lack of reliable and direct measurement methods of the posture, especially for sitting. Recently developed systems with inertial sensor attached along the spine have potential for this purpose. The aim of the present study was therefore to test the reliability of using such a system to assess various seated postures. Inter- and intra-tester as well as intra-subject relative reliability was estimated with intra-class correlation coefficient (ICC). Absolute reliability was estimated with standard error of measurement (SEM) and smallest detectable change (SDC). Ten + ten healthy subjects and four testers participated. Three standardised unsupported seated postures (lumbar lordosis, lumbar kyphosis and neutral posture) and two standing postures (neutral and lumbar kyphosis) were evaluated using five sensors attached to the head, the thorax (high and low), the lumbar spine and the pelvis. The ICC for intra-tester reliability ranged from 0.37 to 0.90, SEM 2.5-12.0 degrees, and SDC 7.1-333 degrees where the largest measurement error was from the head. Intra-tester reliability was higher than inter-tester reliability but not as good as intra-subject reliability. The intra-tester absolute reliability was nevertheless not considered sufficient to distinguish smaller differences. The low reliability may depend on inertial sensor size and attachment but also on the tester's accuracy. This study shows that assessing unsupported seated spinal postures with inertial sensors could be performed with higher reliability if done by the same, rather than different, testers. Relevance to industry: Prolonged awkward seated postures at work may be associated with back and neck pain and should therefore be analysed. Inertial sensor units is a promising tool to measure spinal posture. Smaller sensors attached by one skilled tester directly onto the body will most likely improve assessment in the future. (C) 2014 Elsevier B.V. All rights reserved.

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