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| 2. |
- Holmberg, Hans-Christer, et al.
(författare)
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Reliability and validity of a new double poling ergometer for cross-country skiers
- 2008
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:2, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50 - 70% higher than that at the flywheel. There was a high test - retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W . kg(-1)) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.
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| 3. |
- Johansson, Christer, et al.
(författare)
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Impacts of air pollution and health by changing commuting from car to bicycle
- 2017
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 584-585, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- Our study is based on individual data on people’s home and work addresses, as well as their age, sex and physical capacity, in order to establish realistic bicycle-travel distances. A transport model is used to single out data on commuting preferences in the County Stockholm. Our analysis shows there is a very large potential for reducing emissions and exposure if all car drivers living within a distance corresponding to a maximum of a 30 minute bicycle ride to work would change to commuting by bicycle. It would result in more than 111 000 new cyclists, corresponding to an increase of 209% compared to the current situation.Mean population exposure would be reduced by about 7% for both NOx and black carbon (BC) in the most densely populated area of the inner city of Stockholm. Applying a relative risk for NOx of 8% decrease in all-cause mortality associated with a 10 µg m-3 decrease in NOx, this corresponds to more than 449 (95% CI: 340 - 558) years of life saved annually for the Stockholm county area with 2.1 million inhabitants. This is more than double the effect of the reduced mortality estimated for the introduction of congestion charge in Stockholm in 2006. Using NO2 or BC as indicator of health impacts, we obtain 395 (95% CI: 172 - 617) and 185 (95% CI: 158 - 209) years of life saved for the population, respectively. The calculated exposure of BC and its corresponding impacts on mortality are likely underestimated. With this in mind the estimates using NOx, NO2 and BC show quite similar health impacts considering the 95% confidence intervals.
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| 4. |
- Lövenheim, Boel, et al.
(författare)
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Health risk assessment of reduced air pollution exposure when changing commuting by car to bike
- 2016
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Konferensbidrag (refereegranskat)abstract
- In this study we have assessed the reduction in traffic emissions and population exposure assuming all potential car commuters would switch to biking if they live within 30 minute travel by bike. The scenario would result in more than 100 000 new bikers and due to the reduced traffic emissions 42 premature deaths would be avoided per year. This is almost twice as large effect as the congestion tax in Stockholm. Introduction Regular physical activity has important and wide-ranging health benefits including reduced risk of chronic disease, and physical inactivity is mentioned as perhaps the most important public health problem of the 21st century. At the same time, the direct effects of traffic emissions is a major health problem. Transferring commuting by car to bike will increase physical activity and reduce emissions and reduce population exposure to traffic pollution. The exposure of commuters will also change; new bikers may get higher exposure whilst old bikers and car drivers may get lower exposures, depending on commuting route and distance. Methodology In this study we have calculated the potential number of car-to-bike switching commuters depending on distance, travel time, age of commuters, etc. We have made calculations for a 30-minute biking scenario, i.e. transferring all car commuters to bike if their travel time by bike is less than or equal to 30 minutes. The commuting distance depends on age and sex. For the travel and traffic modelling the LuTrans model was used. It includes all different modes of travel; walking, bicycling, public transport systems and car traffic. The model was developed based on travel survey data and is regularly calibrated using traffic counts. Emissions from road traffic were calculated based on HBEFA 3.2. A Gaussian dispersion model was used estimate exposures over the county of Stockholm. Results The 30 min scenario resulted in 106 881 more bikers, an increase of 2.6 times compared to base scenario. Of all bikers 50% were men and the mean age of all bikers was 42. The traffic emissions of NOx was reduced by up to 7%. Up to 20% reduction in traffic contribution to NOx concentrations was calculated as shown in Figure 1. The mean reduction in concentration for the whole area is 6% and the largest occur were most people live.The population weighted mean NOx concentration for 1.6 million people in Greater Stockholm is estimated to be reduced by 0.41 μg m-3. Assuming that the premature mortality is reduced by 8% per 10 μg m-3 (Nafstad et al., 2004), this corresponds to 42 avoided premature deaths every year or 514 gained life years gained. This is even somewhat more beneficial than the effects of the congestion charge in Stockholm (Johansson et al., 2009), which was estimated to save 27 premature deaths per year. The gain in reduced mortality is almost as large as the gain in health of the increased physical activity. Conclusions Transferring car commuters to bike is not only beneficial for the physical activity, but will also lead to reduced traffic emissions and reduced population exposure. Our estimates show that it may be even more beneficial for mortality due to air pollution exposure than the congestion charge in Stockholm. Acknowledgement This project was funded by the Swedish Research Council for Health, Working life and Welfare. References Johansson, C., Burman, L., Forsberg, B. 2009. The effects of congestions tax on air quality and health. Atmos. Environ. 43, 4843-4854.Nafstad, P., Lund Håheim, L., Wisloeff, T., Gram, G., Oftedal, B., Holme, I., Hjermann, I. and Leren, P. 2004. Urban Air Pollution and Mortality in a Cohort of Norwegian Men. Environ. Health Perspect. 112, 610-615.
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| 5. |
- Nilsson, Johnny E, et al.
(författare)
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Effects of 20-s and 180-s double poling interval training in cross-country skiers
- 2004
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 92:1/2, s. 121-127
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the effect of upper body 20-s or 180-s interval training, using a double poling ergometer, on upper body power output and selected physiological and biomechanical parameters in cross-country skiers. Twenty (12 male, 8 female) well-trained cross-country skiers took part. Two intervention groups, a 20-s interval training group (IT20; n=6) and a 180-s interval training group (IT180; n=7), underwent training three times a week for 6 weeks on a double poling ergometer. A third group served as a control (CON; n=7) and followed the same training program as the IT20 and IT180 groups without the double poling ergometer interval training. The IT20 and IT180 groups significantly (P<0.05) increased both peak and mean power in a 30-s test and mean power in a 6-min test after double poling training. There was a significant improvement in work efficiency in both IT20 and IT180 (P<0.05) and, in IT180, a significant reduction (P<0.05) in blood lactate concentration at given sub-maximal workloads. VO(2peak) increased significantly during double poling in IT180 ( P<0.05) only. VO(2max) did not change significantly in either group. There were no significant changes in any of the test variables in CON. In conclusion, this study shows that 6 weeks of 20-s or 180-s double poling interval training, three times a week, significantly increases power output in both 30-s and 6-min tests, as well as in selected physiological and biomechanical parameters in well-trained cross-country skiers.
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| 6. |
- Nilsson Sommar, Johan, et al.
(författare)
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Overall health impacts of a potential increase in cycle commuting in Stockholm, Sweden
- 2022
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Ingår i: Scandinavian Journal of Public Health. - : Sage Publications. - 1403-4948 .- 1651-1905. ; 50, s. 552-564
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To estimate the overall health impact of transferring commuting trips from car to bicycle..Design and setting: In this study registry information on location of home and work for residents in the County of Stockholm was used to obtain the shortest travel route on a network of bicycle paths and roads. Current modes of travel to work were based on travel survey data. The relation between duration of cycling and distance cycled was established as a basis for selecting the number of individuals that normally would drive a car to their work place, but have a distance to work that they could bicycle within 30 minutes. The change in traffic flows was estimated by a transport model (LuTrans) and effects on road traffic injuries and fatalities were estimated by using national hospital injury data. Effects on air pollution concentrations were modelled using dispersion models.Results: Within the scenario, 111 000 commuters would shift from car to bicycle. This corresponds to 32% of the existing car commuters. On average the increased physical activity reduced the one-year mortality risk by 12% among the additional bicyclists corresponding to 16 fewer premature deaths per year. Including the number of years lost due to morbidity, the total number of disability adjusted life years (DALYs) gained was 696. The amount of DALYs per year gained in the general population due to reduced air pollution concentrations at home addresses was 471. The number of DALYs lost by traffic injuries was 176. Including also air pollution effects among bicyclists, the scenario was calculated to each year give a net benefit of 939 DALYs.Conclusion: The health impact assessment of transferring commuting by car to bicycle estimated large health benefits even then considering injuries and air pollution exposure among bicyclists.
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