| 1. |
- Gao, Chuansi, et al.
(författare)
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Gait muscle activity during walking on an inclined icy surface
- 2008
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Ingår i: Industrial Health. - : National Institute of Industrial Health. - 1880-8026 .- 0019-8366. ; 46:1, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to explain the contribution of lower extremity muscle activity to gait kinetic and kinematic adaptations for maintaining gait dynamic balance when walking on an inclined icy surface and the biomechanical mechanisms used to counteract slip risk. A two-way factorial experimental design was applied. The two independent variables were the walkway surface (ice and treadmill) and the walkway inclination (0º, 6º, 8º). The dependent variable was the amplitude of the surface EMG of four right lower extremity muscles (tibialis anterior TA, gastrocnemius lateralis GL, rectus femoris RF, and biceps femoris BF). Twelve healthy subjects (7 males and 5 females) participated in the walking trials. A two-way ANOVA analysis showed that on the icy surface in the heel contact phase, EMG amplitudes significantly decreased in TA and RF compared to those for the treadmill surface. In the mid-stance phase, the GL muscle activity significantly decreased on ice compared to treadmill and all four muscle activities increased significantly with the inclination. During the toe off phase, GL and RF activities increased with the inclination. The mechanisms identified may be applied to develop intervention, rehabilitation and training techniques, and to improve performance in human locomotion, such as for winter sports.
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| 2. |
- Havenith, Bensahbat, et al.
(författare)
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The UTCI-Clothing Model
- 2012
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Ingår i: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 1432-1254 .- 0020-7128. ; 56:3, s. 461-470
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Tidskriftsartikel (refereegranskat)abstract
- The Universal Thermal Climate Index (UTCI) was conceived as a thermal index covering the whole climate range from heat to cold. This would be impossible without considering clothing as the interface between the person (here, the physiological model of thermoregulation) and the environment. It was decided to develop a clothing model for this application in which the following three factors were considered: (1) typical dressing behaviour in different temperatures, as observed in the field, resulting in a model of the distribution of clothing over the different body segments in relation to the ambient temperature, (2) the changes in clothing insulation and vapour resistance caused by wind and body movement, and (3) the change in wind speed in relation to the height above ground. The outcome was a clothing model that defines in detail the effective clothing insulation and vapour resistance for each of the thermo-physiological model's body segments over a wide range of climatic conditions. This paper details this model's conception and documents its definitions.
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| 3. |
- Kjellström, Tord, et al.
(författare)
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Climate change and occupational heat problems
- 2013
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Ingår i: Industrial Health. - : National Institute of Occupational Safety & Health, Japan. - 0019-8366 .- 1880-8026. ; 51:1, s. 1-2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Kuklane, Kalev, et al.
(författare)
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Subzero project: Thermal insulation measurement of cold protective clothing using thermal manikins - Physiological tests
- 2003
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Ingår i: 2nd European Conference on Protective Clothing (ECPC) and NOKOBETEF 7 : Challenges for Protective Clothing - Challenges for Protective Clothing.
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Konferensbidrag (refereegranskat)abstract
- Wearer trials with human subjects were included in the Subzero project in order to validate the manikins' data against practice. Physiological tests of the project were aimed to study hu-man subjects at thermal comfort or being slightly warm in cold: 0, -10, -25 and wind-chill temperature –50 ºC. Wind-chill temperature –50 was achieved by combination of 2 tempera-tures and wind velocities: -40 ºC and 3 m/s, and -23 ºC and 10 m/s. Moderate activity to keep subjects at thermal comfort without sweating was chosen according to IREQ-neutral (ISO/CD 11079, 2001). High activity was decided to be 50 W/m2 higher than during moderate activity in order to generate considerably more sweat. Walking speeds for moderate activity were 3.5 (0 and -10 °C) and 3.8 (-25 °C), and for high activity 4.9 (0 and -10 °C) and 5.0 km/h (-25 °C). At wind-chill temperature of -50 the walking speed was the same for both wind speeds: 5.0 km/h with 0.5° inclination. Tests involved walking on a treadmill for 90 minutes. Clothing systems without and with water vapour barrier were tested. Wearer trials with human test subjects were carried out at 4 test institutes (study partners 2 (P2), 4 (P4), 5 (P5) and 6 (P6)). P2 and P4 carried out tests at 0 and -10 °C corresponding to ensembles A and B, P5 at -25 °C and -50 wind-chill temperature corresponding to ensembles C and D, and P6 at -10 and -25 °C. 8 young healthy men served as test subjects at each insti-tute. In total 256 single tests were performed. The subjects reached steady state in all clothing systems and stayed at comfort. Conditions with low sweat accumulation can be used to validate manikin measurements. Consideration of ensemble weight distribution, additional energy costs due to thicker clothing and wind veloc-ity and direction could increase prediction accuracy. Manikin tests lead to realistic results that can be used in practice.
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