| 1. |
- Flodgren, G, 1961-, et al.
(författare)
-
Characterization of a laboratory model of computer mouse use : applications for studying risk factors for musculoskeletal disorders
- 2007
-
Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 38:2, s. 213-218
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study, we assessed the wrist kinetics (range of motion, mean position, velocity and mean power frequency in radial/ulnar deviation, flexion/extension, and pronation/supination) associated with performing a mouse-operated computerized task involving painting rectangles on a computer screen. Furthermore, we evaluated the effects of the painting task on subjective perception of fatigue and wrist position sense. The results showed that the painting task required constrained wrist movements, and repetitive movements of about the same magnitude as those performed in mouse-operated design tasks. In addition, the painting task induced a perception of muscle fatigue in the upper extremity (Borg CR-scale: 3.5, p<0.001) and caused a reduction in the position sense accuracy of the wrist (error before: 4.6 degrees , error after: 5.6 degrees , p<0.05). This standardized painting task appears suitable for studying relevant risk factors, and therefore it offers a potential for investigating the pathophysiological mechanisms behind musculoskeletal disorders related to computer mouse use.
|
|
| 2. |
|
|
| 3. |
- Aasa, Ulrika, et al.
(författare)
-
The impact of object size and precision demands on fatigue during computer mouse use
- 2011
-
Ingår i: Advances in Physiotherapy. - : Informa UK Limited. - 1403-8196 .- 1651-1948. ; 13:3, s. 118-127
-
Tidskriftsartikel (refereegranskat)abstract
- Prolonged computer use, especially if fatigue ensues, is associated with visual and musculoskeletal symptoms. The aim was to determine the time-course of perceived fatigue in the wrist, forearm, shoulder and eyes during a 60-min mouse task (painting rectangles), and whether object size and/or mouse use demands were of infl uence. Also, we investigated performance (number of rectangles painted), and whether perceived fatigue was paralleled by local muscle fatigue or tissue oxygenation.Ten women performed the task for three conditions (crossover design). At condition 1, rectangles were 45 25 mm, square paint cursor size 1.3 1.3 mm, and mouse – pointer movement ratio 1:26. At condition 2, the same cursor size and mouse – pointer movement ratio was used, but rectangles were smaller. At condition 3, the smaller rectangles were used, but the cursor size was also smaller and mouse – pointer movement ratio was 1:8. The results showed increased self-reported fatigue over time, with the observed increase greater for the eyes, but no change in physiological responses. Condition 2 resulted in higher performance and increased eye fatigue. Perceived fatigue in the muscles or physiological responses did not differ between conditions. In conclusion, computer work tasks imposing high visual and motor demands, and with high performance, seemed to have an infl uence on eye fatigue.
|
|
| 4. |
- Björklund, Martin, et al.
(författare)
-
Acute muscle stretching and shoulder position sense
- 2006
-
Ingår i: Journal of athletic training. - 1062-6050 .- 1938-162X. ; 41:3, s. 270-274
-
Tidskriftsartikel (refereegranskat)abstract
- Context: Stretching is common among athletes as a potential method for injury prevention. Stretching-induced changes in the muscle spindle properties are a suggested mechanism, which may imply reduced proprioception after stretching; however, little is known of this association. Objective: To evaluate whether acute stretching of the shoulder muscles affects position sense. Design: A crossover design with subjects randomized to 3 groups. Setting: A university human research laboratory. Patients or Other Participants: Nine male (age = 24 +/- 3 years) and 9 female (age = 21 +/- 2 years) healthy volunteers. Intervention(s): Stretching of shoulder (1) agonists or (2) antagonists or (3) nonstretching control. Main Outcome Measure(s): We determined position sense acuity of the right shoulder before and after the interventions by having subjects attempt to reproduce arm positions of 15 degrees and 30 degrees (shoulder adduction) while starting at 45 degrees to the sagittal plane. The outcome variables were response variability (variable error) and overall accuracy (absolute error). Results: The relative change in variable error (ie, variable error after/variable error before) was not significantly different between the interventions ( P = .38). Similarly, no change in absolute error was found ( P = .76). Furthermore, no differences were noted regarding test sequence or the interaction of intervention x sequence for either variable error ( P = .73 and .53, respectively) or absolute error ( P = .71 and .67, respectively). Conclusions: We found no effect on shoulder position sense after an acute bout of stretching of either agonist or antagonist shoulder muscles.
|
|
| 5. |
|
|
| 6. |
- Björklund, Martin, et al.
(författare)
-
Position sense acuity is diminished following repetitive low-intensity work to fatigue in a simulated occupational setting
- 2000
-
Ingår i: European Journal of Applied Physiology and Occupational Physiology. - 0301-5548 .- 1432-1025. ; 81, s. 361-367
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Repetitive work to fatigue is soundly associated with work-related musculoskeletal disorders (WMSD), although the underlying mechanisms are poorly understood. In the present study, we tested the hypothesis that fatiguing work leads to proprioceptive deficits, which can be an initiating factor for the occurrence of WMSD. Thus, the position sense of the shoulder was determined for 13 males and 13 females before and after performing repetitive low-intensity arm work to fatigue in a simulated occupational setting. From a starting position of 45grader to the sagittal plane, position sense tests consisted of subjects attempting to actively reproduce target positions of horizontal move- ments to 15grader and 30grader (shoulder adduction) and to 60grader and 75grader (shoulder abduction). An analysis of variance revealed that the absolute error was significantly increased following fatigue for the subjects as a group (P < 0.001). Furthermore, females had an overall higher error than males (P < 0.01). No difference in error was detected for the shorter movements versus the longer movements. However, the overall absolute error for adduction was significantly higher than for abduc- tion (P < 0.001). The results of the present study support the hypothesis of diminished proprioceptive acuity following low-intensity work to fatigue. A reduction in position sense acuity could lead to impairment in motor control, which would further impact on position sense. Thus, a vicious cycle may be activated that might result in WMSD. The poorer position sense acuity observed for females may contribute to the explanation of why females may contribute to explanation of why females demonstrate a higher incidence of WMSD than males. Key Words: Fatigue, Glenohumeral joint, human, Occupational musculoskeletal problems,Proprioception.
|
|
| 7. |
- Björklund, Martin, et al.
(författare)
-
Position sense acuity is diminished following repetitive low-intensity work to fatigue in a simulated occupational setting.
- 2000
-
Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 81:5, s. 361-367
-
Tidskriftsartikel (refereegranskat)abstract
- Repetitive work to fatigue is soundly associated with work-related musculoskeletal disorders (WMSD), although the underlying mechanisms are poorly understood. In the present study, we tested the hypothesis that fatiguing work leads to proprioceptive deficits, which can be an initiating factor for the occurrence of WMSD. Thus, the position sense of the shoulder was determined for 13 males and 13 females before and after performing repetitive low-intensity arm work to fatigue in a simulated occupational setting. From a starting position of 45° to the sagittal plane, position sense tests consisted of subjects attempting to actively reproduce target positions of horizontal movements to 15° and 30° (shoulder adduction) and to 60° and 75° (shoulder abduction). An analysis of variance revealed that the absolute error was significantly increased following fatigue for the subjects as a group (P < 0.001). Furthermore, females had an overall higher error than males (P < 0.01). No difference in error was detected for the shorter movements versus the longer movements. However, the overall absolute error for adduction was significantly higher than for abduction (P < 0.001). The results of the present study support the hypothesis of diminished proprioceptive acuity following low-intensity work to fatigue. A reduction in position sense acuity could lead to impairment in motor control, which would further impact on position sense. Thus, a vicious cycle may be activated that might result in WMSD. The poorer position sense acuity observed for females may contribute to the explanation of why females demonstrate a higher incidence of WMSD than males.
|
|
| 8. |
- Björklund, Martin, et al.
(författare)
-
Repetitive low-back-level arm activity to fatigue diminishes limb position sense
- 1999
-
Konferensbidrag (refereegranskat)abstract
- Position sense awareness of the shoulder was determined for 9 males and 9 females before and after performing repetitive low-level arm activity to fatigue. The activity consisted of continuous horizontal internal and external rotations. Position sense awareness tests were performed with subjects blindfolded and seated with the arm in a motorized rig. The subjects were asked to actively reproduce test positions of 10°, 25°, 55° and 70° randomly assigned, while starting at 40° (relative to the sagittal plane). The tests were conducted immediately before and after the fatiguing activity. An ANOVA revealed that the absolute error, measured as test position minus reproduced position, was significantly increased following fatigue for the subjects as a group (p<0.001 ). Furthermore, females had overall higher error than males (p<0.05). The results indicate that repetitive low-level activity to fatigue leads to proprioceptive deficits. These deficits can create a non-optimized motor control, causing an increase in the co-activation of agonist and antagonist muscles and thus increasing the work-load. This could create an unfavorable cycle of events, which would further impact proprioception and thereby enhance the risks for muscle pain and injury. The higher incidence of injuries for female athletes compared to males may be attributed to gender differences in proprioception.
|
|
| 9. |
- Björklund, Martin, et al.
(författare)
-
Sensory adaptation after a 2-week stretching regimen of the rectus femoris muscle
- 2001
-
Ingår i: Archives of Physical Medicine and Rehabilitation. - : Elsevier BV. - 0003-9993 .- 1532-821X. ; 82:9, s. 1245-1250
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the effects of a muscle stretching regimen for the rectus femoris muscle on subjective stretch sensation and range of motion (ROM). DESIGN: A 2 x 2 crossover design comprising 2 treatments and 2 intervention periods. SETTING: A military base in Sweden. PARTICIPANTS: A volunteer sample of 29 male military conscripts divided into 2 groups, with each group subjected to both experimental and control treatments at different time periods. INTERVENTION: Two weeks of supervised stretching (4 times/wk) of the rectus femoris muscle (experimental treatment) and the calf muscles (control treatment). MAIN OUTCOME MEASURES: Subjective rating of the stretch sensation for the anterior aspect of the thigh determined on a category ratio scale. Passive knee flexion ROM determined on each test with the same applied torque, specific for each subject. RESULTS: An additive analysis of variance revealed that the stretch sensation after the experimental treatment was decreased, compared with the control treatment (p <.01). The knee flexion, however, remained the same regardless of the treatment. CONCLUSION: Sensory adaptation seems to be an important mechanistic factor in the effect stretching has on ROM changes. The lack of change in knee flexion suggests that the stretching, as performed in this study, did not influence stiffness of the rectus femoris muscle. Sensory adaptation may also be an underlying mechanism in the alleviating effect of stretching when applied to tired, tender, and painful muscles.
|
|
| 10. |
|
|
