| 1. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Design and development of a climatic wind tunnel for physiological sports experimentation
- 2019
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part P. - : SAGE Publications. - 1754-3371. ; 233:1, s. 86-100
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this project was to develop a wind tunnel that enables the study of human performance during various types ofsports and physical activities by examining the influence of aerodynamic drag, precipitation, frictional forces and gravitationalforces on uphill and downhill travel on a moving substrate. An overall design for a wind tunnel and working section containinga large treadmill was drafted, followed by computational fluid dynamics simulations of flow conditions to assess thedesign’s feasibility and select from different geometries prior to its construction. The flow conditions in the completed windtunnel were validated using different flows, speeds and treadmill inclinations. Pilot experiments were carried out using across-country skier to investigate the effect of aerodynamic drag on oxygen uptake during double poling and the maximalachieved speed when rolling on a declined treadmill. The purpose was to validate the usefulness of the tunnel. The resultsshowed that flow conditions are acceptable for experiments even in worst-case scenarios with maximal inclined and declinedtreadmill. Results also showed that aerodynamic drag has a significant impact on the skier’s energy expenditure.
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| 2. |
- Sjöström, Lars, et al.
(författare)
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Bariatric surgery and long-term cardiovascular events.
- 2012
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Ingår i: JAMA : the journal of the American Medical Association. - : American Medical Association (AMA). - 1538-3598. ; 307:1, s. 56-65
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Tidskriftsartikel (refereegranskat)abstract
- Obesity is a risk factor for cardiovascular events. Weight loss might protect against cardiovascular events, but solid evidence is lacking.
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| 3. |
- Sjöström, Lars, et al.
(författare)
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Effects of bariatric surgery on mortality in Swedish obese subjects.
- 2007
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Ingår i: The New England journal of medicine. - 1533-4406. ; 357:8, s. 741-52
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Obesity is associated with increased mortality. Weight loss improves cardiovascular risk factors, but no prospective interventional studies have reported whether weight loss decreases overall mortality. In fact, many observational studies suggest that weight reduction is associated with increased mortality. METHODS: The prospective, controlled Swedish Obese Subjects study involved 4047 obese subjects. Of these subjects, 2010 underwent bariatric surgery (surgery group) and 2037 received conventional treatment (matched control group). We report on overall mortality during an average of 10.9 years of follow-up. At the time of the analysis (November 1, 2005), vital status was known for all but three subjects (follow-up rate, 99.9%). RESULTS: The average weight change in control subjects was less than +/-2% during the period of up to 15 years during which weights were recorded. Maximum weight losses in the surgical subgroups were observed after 1 to 2 years: gastric bypass, 32%; vertical-banded gastroplasty, 25%; and banding, 20%. After 10 years, the weight losses from baseline were stabilized at 25%, 16%, and 14%, respectively. There were 129 deaths in the control group and 101 deaths in the surgery group. The unadjusted overall hazard ratio was 0.76 in the surgery group (P=0.04), as compared with the control group, and the hazard ratio adjusted for sex, age, and risk factors was 0.71 (P=0.01). The most common causes of death were myocardial infarction (control group, 25 subjects; surgery group, 13 subjects) and cancer (control group, 47; surgery group, 29). CONCLUSIONS: Bariatric surgery for severe obesity is associated with long-term weight loss and decreased overall mortality.
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| 4. |
- Ainegren, Mats, 1963-, et al.
(författare)
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A portable roller ski rolling resistance measurement system
- 2013
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Ingår i: The Impact of Technology on Sport V. - : Elsevier. ; , s. 79-83
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Konferensbidrag (refereegranskat)abstract
- Roller skis are used by cross-country skiers, biathletes and ski-orienteers for their snow-free training and in roller ski competitions. Additionally, much of the current sports research into the physiology and biomechanics of crosscountry skiing is conducted indoors on treadmills using roller skis. For elite athletes, the differences in performance are quite small, thus emphasising the importance of knowing the roller skis' rolling resistance coefficient, especially in connection to research and roller ski competitions. The purpose of this study was to develop a roller ski rolling resistance measurement system (P-RRMS) that is portable and therefore useful in different contexts and locations. The P-RRMS was designed as a small treadmill, equipped with roller ski stabilizing lateral supports and a screwed bar for applying different vertical loads on the roller ski. The design uses only one force sensor, with possible measurements of three directions of force and torque around three axes. The weight of the P-RRMS is 100 kg and it is equipped with wheels to facilitate transportation.
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| 5. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Roller ski rolling resistance and its effects on elite athletes’ performance
- 2009
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Ingår i: Sports Engineering. - Paris : Springer. - 1369-7072 .- 1460-2687. - 9782287990564 - 9782287990557 ; 11:3, s. 143-157
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Tidskriftsartikel (refereegranskat)abstract
- Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes, the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study, the roller skis’ rolling resistance was measured on the ski-treadmill’s surface using a roller ski rolling resistance measurement system specially produced for this purpose. The study investigated the influence of significant changes in rolling resistance on physiological variables. The results showed that during submaximal exercise, power, oxygen uptake, heart rate and blood lactate were significantly changed by different rolling resistances, while there were no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed by different rolling resistances and this occurred without significant changes in maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion were insignificant or small.
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| 6. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Roller ski rolling resistance and its effects on elite athletes’ performance
- 2008
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Ingår i: ENGINEERING OF SPORT 7, VOL 2. - 9782287094125 ; , s. 393-400
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Konferensbidrag (refereegranskat)abstract
- Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study the roller skis’ rolling resistance has been measured using equipment on the ski-treadmill. The study investigates the influence of significant changes in rolling resistance on physiological variables. The results show that during submaximal exercise, heart rate, blood lactate, power and oxygen uptake are significantly changed by different rolling resistances, while there are no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests show that time to exhaustion is significantly changed by different rolling resistances and this occurred without significant changes in maximal oxygen uptake and heart rate, and the influence on maximal power and ratings of perceived exertion were insignificant or small.
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| 7. |
- Ainegren, Mats, 1963-, et al.
(författare)
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The multifunctional roller ski
- 2013
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Ingår i: Science and Nordic Skiing II. - : University of Salzburg, University of Jyväskylä. - 9789513951757 ; , s. 253-261
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Bokkapitel (refereegranskat)
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| 8. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Work economy of amateur and elite cross-country skiers during treadmill roller skiing
- 2009
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Ingår i: 4th Asia Pacific Congress on Sports Technology, APCST2009. - 9781921426384
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Konferensbidrag (refereegranskat)abstract
- This study focused on the work economy of cross-country skiers during treadmill roller skiing in the perspectives; skill, age and gender. The study was investigating the external power output from elevating the transported mass against gravity and overcoming the roller skis rolling resistance, and the internal power from measured oxygen uptake and energy consumption. The roller skis rolling resistance was measured with a fixture on the ski-treadmill and the results showed a significant correlation between normal force and rolling resistance. The results also showed that it was only the amateur skiers who significantly differed in work economy among the five studied groups.
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| 9. |
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| 10. |
- Carlsson, Peter, 1950-, et al.
(författare)
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Numerical Simulation of Cross Country Skiing
- 2011
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Ingår i: Computer Methods in Biomechanics and Biomedical Engineering. - : Informa UK Limited. - 1025-5842 .- 1476-8259. ; 14:8, s. 741-746
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Tidskriftsartikel (refereegranskat)abstract
- A program for numerical simulation of a whole ski race, from start to finish, is developed in MATLAB. The track ismodelled by a set of cubical splines in two dimensions and can be used to simulate a track in a closed loop or with the startand finish at different locations. The forces considered in the simulations are gravitational force, normal force between snowand skis, drag force from the wind, frictional force between snow and ski and driving force from the skier. The differentialequations of motion are solved from start to finish with the Runge–Kutta method. Different wind situations during the racecan be modelled, as well as different glide conditions on different parts of the track. It is also possible to vary the availablepower during the race. The simulation program’s output is the total time of the race, together with the forces and speedduring different parts of the race and intermediate times at selected points. Some preliminary simulations are also presented.
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