<p>Background: The majority of the occupational accidents and work-related diseases at Swedish workplaces occur due to poor ergonomics during lifts and transportation of objects. The most common consequence of poor ergonomic conditions is low back pain (LBP) and the risk of developing LBP increases as the mechanical loading on the intervertebral disks grows. This study has investigated the biomechanical loading in the low back during two different types of patient lifts. The first lift (lift A) is developed by Modern Arbetsteknik (MA) and the second lift (lift B) is a common lifting technique among care workers. </p><p>Objectives: The aim of the study was to identify any advantages or disadvantages with MA’s lift, regarding shear and compression forces in the L5/S1 disc. The calculated forces were also compared with lifting recommendations from the Swedish Work Environment Authority and the National Institute for Occupational Safety and Health (NIOSH).</p><p>Methods: The lifting techniques were evaluated with biomechanical calculations, Dartfish video analysis software, Qualisys motion capture system and the biomechanical analysis software Visual3D. </p><p>Results: Lift A was less stressful on the low back than lift B. Particularly during lift start, when the mechanical loading from the patient reaches the highest level. The disadvantage of lift B is that it results in greater axial rotation and asymmetrical loading. This causes greater shear and torsion forces, which are associated with LBP. </p><p>Conclusions: The mechanical loading of the spine exceeds the limits recommended by the Swedish Work Environment Authority and NIOSH. Therefore the maximum allowed patient weight for a three person lift should be lowered, in order to reduce the risk for LBP.</p>

Background: The majority of the occupational accidents and work-related diseases at Swedish workplaces occur due to poor ergonomics during lifts and transportation of objects. The most common consequence of poor ergonomic conditions is low back pain (LBP) and the risk of developing LBP increases as the mechanical loading on the intervertebral disks grows. This study has investigated the biomechanical loading in the low back during two different types of patient lifts. The first lift (lift A) is developed by Modern Arbetsteknik (MA) and the second lift (lift B) is a common lifting technique among care workers. Objectives: The aim of the study was to identify any advantages or disadvantages with MA’s lift, regarding shear and compression forces in the L5/S1 disc. The calculated forces were also compared with lifting recommendations from the Swedish Work Environment Authority and the National Institute for Occupational Safety and Health (NIOSH). Methods: The lifting techniques were evaluated with biomechanical calculations, Dartfish video analysis software, Qualisys motion capture system and the biomechanical analysis software Visual3D. Results: Lift A was less stressful on the low back than lift B. Particularly during lift start, when the mechanical loading from the patient reaches the highest level. The disadvantage of lift B is that it results in greater axial rotation and asymmetrical loading. This causes greater shear and torsion forces, which are associated with LBP. Conclusions: The mechanical loading of the spine exceeds the limits recommended by the Swedish Work Environment Authority and NIOSH. Therefore the maximum allowed patient weight for a three person lift should be lowered, in order to reduce the risk for LBP.

AbstractIntroduction: Hand Arm Risk Assessment Method (HARM) is a tool to assess the risks of deve­lo­ping complaints of the arm, neck or shoulders during manual work. The method was developed in the Netherlands primarily for employers, but is also used as an aid to work environment in­spec­tors. The purpose of this study was to evaluate the HARM-method for assessment of biomecha­nical exposure of the upper limbs when performing manual tasks as well as its suitability to be used within work environment inspection. Methods: Ten labour inspectors conducted assessments of five video-recorded work tasks. Assess­ments made with HARM were compared with those made with the Assessment of Re­pe­titive Tasks (ART) tool and with ACGIH Hand Actvity Level (HAL) - both methods for assess­ment of bio­mecha­nical exposure of the upper limbs - and with the model for the assessment of re­pe­titive work in the pro­visions of the Swedish Work Environ­ment Autho­rity on ergonomics for the prevention of mus­culo­skeletal disorders, AFS 1998:1. HAL is based on a threshold limit value for hand activity. The method combines the assessment of hand activity with per­ceived effort in the hand and forearm. The assess­ments were made twice, two weeks apart. Following each assessment the inspec­tors answered questions about the suitability of each method. Three experts (X) made the same assess­­ments, first individually just like the inspectors’, and then they agreed upon a consensus estimation. Head and upper arm position were registered by inclinometer, wrist movements with electro goniometer. The observers' assessments were com­pared with a “gold standard” that was created by the results of the technical measure­ments which re­placed the consensus esti­mates for the head and arm positions as well as wrist motions in the HARM, ART and HAL assessments. Results: The inspectors' assessment of HARM and ART showed in comparison with the res­pective “gold standard” some under­esti­ma­tion of risks. Conformity in the test-retest was 68 % at appraisal with HARM and 66 % with ART. Based on the inspectors' observations it was re­vealed that force and frequency were experienced as the most difficult to assess. On the other hand the indi­vi­dual assess­ments indicated that the work position of the hand and forearm showed the lar­gest deviation. Hand activity was both over and undervalued in comparison with tech­nical measurements, suggesting that it is difficult to simply assess hand activity by ob­ser­va­tion. Fur­thermore, the model for identifying repetitive work in AFS 1998:1 was perceived to be the most difficult to use for performing assess­ments, as it has few criteria and no support for the assessment of hand/arm and hand inten­si­ve move­ments. This under­lines that there is a need for other models as a supplement to the pro­visions. Conclusions: The results showed that the HARM and ART are relatively similar in content and struc­ture and provided relatively similar results. HARM is more detailed than ART as it takes into account the vibration exposure as a single factor and shows more consideration to the duration of exposure. The HARM-method provides support for the assessment; it is easy to use, it needs pen and paper only and is in that sense readily available, it is fast and takes into account the whole of the assessment of biomechanical exposure of the upper limbs. ART is very similar to HARM; HAL is more limited and can be used as a rapid screening of hand load. / Sammanfattning Inledning: Hand Arm RiskbedömningsMetod (HARM) är ett verktyg för bedömning av be­last­ning på hand och arm vid manuellt arbete. Metoden är framtagen i Nederländerna, i första hand till arbets­gi­va­re, metoden används också som ett stöd för arbetsmiljöinspektörer. Syftet med den här studien var att utvärdera HARM-metodens tillförlitlighet och dess lämp­lig­het som hjälpmedel för arbetsmiljö­inspek­törer vid riskbedömning av belastning på hand, arm och axel vid ma­nuellt arbete. Metod: Tio observatörer tillika arbetsmiljöinspektörer genomförde bedömningar av fem video­inspe­la­de arbets­moment.  Bedömningar gjorda med HARM jämfördes med bedöm­ningar med Assessment of Repetitive Tasks (ART) och Hand Activity Level (HAL) samt modellen för bedömning av ensidigt upprepat arbete i Arbetsmiljöverkets föreskrifter om belastningsergonomi, AFS 1998:1. HAL bygger på ett gränsvärde för handaktivitet. Metoden kombinerar bedömning av handens aktivitet med upplevd ansträng­ning i hand och underarm. Bedömningarna gjordes två gånger med två veckors mellanrum. I anslutning till varje bedömning besvarades frågor om respektive metods användbarhet. Tre experter (X) gjorde först enskilt mot­sva­rande bedömningar som observatörerna och enades därefter i en kon­sen­sus­be­döm­ning. Huvudets- och över­armarnas position registrerades med inklinometer, hand­leds­rö­rel­ser med elektro­gonio­me­ter. En ”gyllene standard” som observatörernas mätningar kunde jämföras med, skapades genom att resultaten av de tekniska mätningarna ersatte konsensusbedömningen för huvud- och armposition samt handledsrörelserna för HARM, ART och HAL. Resultat: Observatörernas bedömningar med HARM och ART visade i jämförelse med respektive gyllene standard på en viss undervärdering av risker. Överensstämmelsen vid test-retest av arbets­momenten var 68 % vid bedömning med HARM och 66 % med ART. Av observatörernas synpunkter framkom att kraft­ och frekvens upplevdes svårast att bedöma. Av de enskilda bedömningarna framkom dock att det var arbets­ställning i hand och underarm som visade den största avvikelsen. Handaktivitet både över- och undervärderades i jämförelse med tekniska mätningar, vilket pekar på att det är svårt att enbart genom ob­ser­va­tion bedöma handaktivitet. Vidare framgick att AFS upplevdes vara svårast att an­vän­da som underlag till en belastnings­ergono­misk riskbedömning, då den har få kriterier och saknar bedömnings­stöd för hand/arm och hand­in­tensiva rörelser. Detta understryker att det kan behövas ett komplement till AFS. Slutsatser: Resultaten visade att HARM och ART är relativt lika till innehåll och struktur och gav förhållandevis likvärdiga resultat. HARM är mer nyanserad än ART då den dels tar hänsyn till vibrationsexponering som en enskild faktor och dels justerar för exponeringstid. HARM-metoden ger stöd vid bedömning, är snabb och lätt att använda, endast papper och penna krävs och den tar hänsyn till hel­heten vid be­döm­ning av nack- och arm belastning. ART är mycket lik HARM. HAL är mer begränsad och kan användas som en snabb screeningmetod för handbelastning.

Bone loss and muscle atrophy are two main physiological conditions affecting astronauts while being in space. In order to counteract the effects, at least two hours of aerobic and resistant countermeasure exercise is scheduled into their working day, seven days a week. Yoyo Technology AB has developed a resistance exercise device based on the flywheel principle, providing a load independent of gravity. However, there is no biomechanical research done on the efficiency of the device in microgravity, from a human movement point of view using simulation software. The aim of this thesis was to evaluate the effects of performing a leg press on the flywheel exercise device in a microgravity environment. Simulations of performing a flywheel leg press in earth gravity, microgravity and performing a conventional squat were done. The evaluated parameters were reaction forces, joint angles, joint moments, joint powers and muscle recruitment in the lower extremities. The simulations were done using a biomechanical simulation software based on a motion capture data collection. From the results two conclusions were proposed. Performing a flywheel leg press in microgravity environment or on earth provides at least as much peak moment as a body weighted squat performed on earth. Furthermore, performing a flywheel leg press in microgravity will induce a higher activity level among hip extensors and knee flexors compared to performing a flywheel leg press on earth.