| 1. |
- Ainegren, Mats, et al.
(författare)
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An experimental study to compare the grip of classical style roller skis with on-snow skiing
- 2013
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; 16:2, s. 115-122
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Tidskriftsartikel (refereegranskat)abstract
- Cross-country skiers use roller skis for their snow-free training with the aim of imitating skiing on snow. Also, exercise laboratories evaluate the biomechanics and physiology of cross-country skiing using roller skis on a treadmill. The roller skis on the market that are constructed for use in the classical style are equipped with a front and a back wheel, one of which has a ratchet to enable it to grip the surface when diagonal striding and kick double poling (static friction). The aim of this study was to investigate static friction coefficients (μS) of ratcheted wheel roller skis, and compare the results to the μS reported from skiing on snow with grip-waxed cross-country skis. Also, a new type of roller ski with a camber and adjustable grip function was evaluated. The results showed that ratcheted wheel roller skis, on a treadmill rubber mat and on dry and wet asphalt surfaces, reached μS values that were five to eight times greater than the values reported from on-snow skiing with grip-waxed cross-country skis. For the roller skis with a camber and adjustable grip function, the μs could be varied from no grip at all up to the level of the tested ratcheted wheel roller skis.
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| 2. |
- 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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| 3. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Rolling resistance for treadmill roller skiing
- 2008
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Ingår i: Sports Engineering. - : Springer. - 1369-7072 .- 1460-2687. ; 11:1, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- Modern treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance under laboratory conditions using classical and freestyle techniques on roller skis. The differences in performance between tests are quite small for elite athletes, and it is therefore of great importance to control the rolling resistance of the roller skis. Otherwise different physiological tests cannot be accurately compared.This study shows that during a warm-up period of 30 minutes the coefficient of rolling resistance (µR) decreases to about 60-65% and 70-75% of its initial value for freestyle and classical roller skis respectively.Simultaneous measurements of temperature and µR shows that stabilized rolling resistance corresponds to a certain running temperature for a given normal force on the roller ski.Tests were also performed on the influence on µR of normal force, velocity and inclination. Normal forces produced significant influence on µR , while different velocities and inclinations of the treadmill only resulted in small changes in µR.
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| 4. |
- Allen, T., et al.
(författare)
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Winter sports special issue
- 2017
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; 20:4, s. 243-244
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Brunnström, Kjell, 1960-, et al.
(författare)
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Quality measurement methods for video assisting refereeing systems
- 2023
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Ingår i: Sports Engineering. - : Springer Science and Business Media Deutschland GmbH. - 1369-7072 .- 1460-2687. ; 26:1
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the footballing world’s approach to technology and innovation, along with major advancements in broadcasting contributed to the decision by the International Football Association Board to introduce Video Assistant Referees in 2018. The change meant that under strict protocols referees could use video replays to review decisions in the event of a “clear and obvious error” or a “serious missed incident”. At the time of writing 48-Member Associations have introduced the Video Assistant Referees protocol in at least one of their tournaments and there are many technology providers who work with organisers to implement the Video Assistant Referees systems. To ensure that the use of Video Assistant Referees has a positive effect on the game, Fédération Internationale de Football Association collaborated with the RISE Research Institutes of Sweden to develop objective test methods that could be used to ensure that a system can provide an adequate solution. Each provider must be able to pass requirements that ensure that they can deal with the challenges of processing, coding, decoding, synchronising, and re-formatting of the broadcast feeds. This article will describe the development of the test methods and illustrate some initial results from a test event on Video Assistant Referees system candidates. The methods have shown to be robust and appropriate for their intended purpose and will be developed over the years to ensure the quality of Video Assistant Referees. The developed measurement methods are general and can be applied to other broadcast and video systems as well as to other sports. © 2023, The Author(s).
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| 6. |
- Dubus, Gaël, et al.
(författare)
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Exploration and evaluation of a system for interactive sonification of elite rowing
- 2015
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Ingår i: Sports Engineering. - : Springer London. - 1369-7072 .- 1460-2687. ; 18:1, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, many solutions based on interactive sonification have been introduced for enhancing sport training. Few of them have been assessed in terms of efficiency or design. In a previous study, we performed a quantitative evaluation of four models for the sonification of elite rowing in a non-interactive context. For the present article, we conducted on-water experiments to investigate the effects of some of these models on two kinematic quantities: stroke rate value and fluctuations in boat velocity. To this end, elite rowers interacted with discrete and continuous auditory displays in two experiments. A method for computing an average rowing cycle is introduced, together with a measure of velocity fluctuations. Participants answered to questionnaires and interviews to assess the degree of acceptance of the different models and to reveal common trends and individual preferences. No significant effect of sonification could be determined in either of the two experiments. The measure of velocity fluctuations was found to depend linearly on stroke rate. Participants provided feedback about their aesthetic preferences and functional needs during interviews, allowing us to improve the models for future experiments to be conducted over longer periods.
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| 7. |
- Gilenstam, Kajsa, 1974-, et al.
(författare)
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Influence of stick stiffness and puck weight on puck velocity during slap shots in women's ice hockey
- 2009
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; 11:3, s. 103-107
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have found that reduced stick stiffness increases puck velocity in young male ice hockey players. This study investigates the hypothesis that female players are disadvantaged by using equipment that is designed for taller and stronger players. The purpose of this study was to investigate if stick flexibility and puck weight affect puck velocity in standing slap shots performed by female ice hockey players. There was a significant increase in puck velocity (4.1% p=0.037) when stick stiffness and puck weight were reduced. ANOVA revealed that there was a significant correlation between stick, puck and the participant herself (R2=0.987). Spearman’s correlation analysis revealed that participants with higher puck velocities benefitted the most when the stick flexibility and puck weight were reduced (r=0.648; p=0.043). It was concluded that decreased stick stiffness and puck weight increased puck velocity in standing slap shots for female ice hockey players.
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| 8. |
- Gullstrand, Lennart, et al.
(författare)
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A new method for recording the temporal pattern of stride during treadmill running
- 2009
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; :11, s. 195-200
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the reliability of a new infrared light based method (IR40) for recording temporal stride patterns during treadmill running. The IR40 device, emitting a tight web of 40 infrared light beams 10 mm above the treadmill running surface, was compared to a previously validated electro-pneumatic contact shoe (CS) method while nine well-trained athletes ran at 2.8, 3.3, 3.9, 4.4, 5.0, and 5.6 m s−1. Disconnection and reconnection of the IR beams marked the stance phase. The sampling rate was 500 Hz for both methods. The stance phase duration was on average 11.5 (±8.4) ms longer with the IR40 than with the CS depending on earlier touch down (8.3 ± 6.2 ms) and delayed toe off (3.2 ± 5.3 ms) registrations. Significantly different stance phases were recorded between all velocities and for both methods. Thus, despite the fact that the IR40 systematically measured a somewhat longer stance phase duration than CS, the IR40 is nonetheless useful for temporal stride analysis during treadmill running.
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| 9. |
- Hofmann, K. B., et al.
(författare)
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The influence of sitting posture on mechanics and metabolic energy requirements during sit-skiing : a case report
- 2016
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; 19:3, s. 213-218
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Tidskriftsartikel (refereegranskat)abstract
- Several different sitting postures are used in Paralympic cross-country sit-skiing. The aim of this study was to evaluate the impact of sitting posture on physiological and mechanical variables during steady-state double-poling sit-skiing, as well as to determine how seat design can be improved for athletes without sufficient trunk control. Employing a novel, custom-designed seat, three trunk positions were tested while performing double-poling with submaximal oxygen consumption on an ergometer. Cycle kinematics, pole forces, and oxygen consumption were monitored. The athlete performed best, with longer cycle length and less pronounced metabolic responses, when kneeling with the trunk resting on a frontal support. For this case, a forward leaning trunk with knees below the hip joint was interpreted as most optimal, as it showed lower oxygen consumption and related parameters of performance during cross-country sit-skiing. Further investigations should examine whether such improvement is dependent on the level of the athlete’s handicap, as well as whether it is also seen on snow.
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| 10. |
- Jensby Nedergaard, Niels, et al.
(författare)
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The effect of light reflections from the snow on kinematic data collected using stereo-photogrammetry with passive markers
- 2014
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Ingår i: Sports Engineering. - : Springer Science and Business Media LLC. - 1369-7072 .- 1460-2687. ; 17:2, s. 97-102
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to compare kinematic data collected during ski-cross starts outdoors on snow in daylight (high albedo) to similar data collected indoors with infiltrating sunlight but without light reflections from the snow (low albedo) using a video-based motion capture system with the active filtering function enabled. A 12-camera 3D motion capture system (Qualisys AB, Sweden) was used to measure test objects and eight skiers performing a ski-cross start on a slope outdoors and on a wooden start ramp indoors. The average residuals and standard deviations of the length of the calibration wand calculated indoors and outdoors by the calibration software were compared using descriptive statistics. Static and moving fixed length measures and thigh length measures were compared using Bland-Altman plots. Calibration residuals were slightly increased outdoors (1.77 mm) compared to indoors (1.54 mm), while wand length varied by 3.63 and 1.51 mm, respectively. Fixed static lengths differed by -8.65 ± 4.94 mm (shorter indoors), whereas fixed moving lengths differed by 0.85 ± 1.05 mm (longer indoors). A randomly chosen marker pair on one segment (Thigh) showed a mean difference of 1.19 ± 22.05 mm (longer indoors). It is concluded that 3D motion capture outdoors on snow in daylight is feasible, provides kinematic data comparable to indoors, and could be used to research biomechanics in snow sports.
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