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Kersting, U. G.
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Publications (10 of 10) Show all publications
Hofmann, K. B., Ohlsson, M. L., Höök, M., Danvind, J. & Kersting, U. G. (2016). The influence of sitting posture on mechanics and metabolic energy requirements during sit-skiing: a case report. Sports Engineering, 19(3), 213-218
Open this publication in new window or tab >>The influence of sitting posture on mechanics and metabolic energy requirements during sit-skiing: a case report
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2016 (English)In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 19, no 3, p. 213-218Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Biomechanics, Oxygen consumption, Poling force, Seat, Sit-ski
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-28014 (URN)10.1007/s12283-016-0209-7 (DOI)000387943300010 ()2-s2.0-84982712590 (Scopus ID)
Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2018-02-08Bibliographically approved
Nedergaard, N. J., Heinen, F., Sloth, S., Holmberg, H.-C. & Kersting, U. G. (2015). Biomechanics of the ski cross start indoors on a customised training ramp and outdoors on snow. Sports Biomechanics, 14(3), 273-286
Open this publication in new window or tab >>Biomechanics of the ski cross start indoors on a customised training ramp and outdoors on snow
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2015 (English)In: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 14, no 3, p. 273-286Article in journal (Refereed) Published
Abstract [en]

An effective start enhances an athlete's chances of success in ski cross competitions. Accordingly, this study was designed to investigate the biomechanics of start techniques used by elite athletes and assess the influence of different start environments. Seven elite ski cross athletes performed starts indoors on a custom-built ramp; six of these also performed starts on an outdoor slope. Horizontal and vertical forces were measured by force transducers located in the handles of the start gate and a 12-camera motion capture system allowed monitoring of the sagittal knee, hip, shoulder, and elbow kinematics. The starting movement involved Pre, Pull, and Push phases. Significant differences between body sides were observed for peak vertical and resultant forces, resultant impulse, and peak angular velocity of the shoulder joint. Significantly lower peak vertical forces (44N), higher resultant impulse (0.114Ns/kg), and knee joint range of motion (12 degrees) were observed indoors. Although movement in the ski cross start is generally symmetrical, asymmetric patterns of force were observed among the athletes. Two different movement strategies, i.e. pronounced hip extension or more accentuated elbow flexion, were utilised in the Pull phase. The patterns of force and movement during the indoor and outdoor starts were similar.

Keywords
Asymmetry, kinetics, kinematics, ski cross, start technique
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-26524 (URN)10.1080/14763141.2015.1052543 (DOI)000363983900001 ()26158297 (PubMedID)2-s2.0-84946476361 (Scopus ID)
Available from: 2015-12-16 Created: 2015-12-16 Last updated: 2017-12-01Bibliographically approved
Ferdinands, R. E., Kersting, U. G. & Marshall, R. N. (2014). A new taxonomic system for the sub-classification of cricket bowling actions. Sports Technology, 7(1-2), 26-38
Open this publication in new window or tab >>A new taxonomic system for the sub-classification of cricket bowling actions
2014 (English)In: Sports Technology, ISSN 1934-6182, E-ISSN 1934-6190, Vol. 7, no 1-2, p. 26-38Article in journal (Refereed) Published
Abstract [en]

The mixed bowling action is associated with injuries in the lumbar spine and has been shown to have no performance benefits over other bowling actions. The purpose of this study was to assess the mixed bowling action with reference to a more comprehensive classification system to facilitate the development of more targeted bowling action remediation programs. A total of 70 fast bowlers were tested using a three-dimensional motion analysis system (240 Hz). Kinematic data of the shoulders and pelvis were analysed with respect to a modified set of angle threshold criteria to classify bowling actions. It was found that the mixed action bowlers (49% of the sample) could be sub-divided into seven distinct mixed action types. The most common of these types were the mixed front-on bowlers with respect to shoulder counter-rotation (19%) and the mixed front-on bowlers with respect to both pelvis-shoulder separation angle and shoulder counter-rotation (14%). It is envisaged that a more comprehensive classification of bowling actions may assist researchers in the future to define mixed action types with a tighter domain of variables that are more indicative of lumbar injury risk. © 2014 Taylor & Francis.

Keywords
action classification, back injury, counter-rotation, cricket, fast bowling, mixed action
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-25933 (URN)10.1080/19346182.2014.893350 (DOI)2-s2.0-84938868294 (Scopus ID)
Note

Export Date: 23 September 2015

Available from: 2015-09-23 Created: 2015-09-23 Last updated: 2017-12-01Bibliographically approved
Jensby Nedergaard, N., Heinen, F., Sloth, S., Hébert-Losier, K., Holmberg, H.-C. & Kersting, U. (2014). The effect of light reflections from the snow on kinematic data collected using stereo-photogrammetry with passive markers. Sports Engineering, 17(2), 97-102
Open this publication in new window or tab >>The effect of light reflections from the snow on kinematic data collected using stereo-photogrammetry with passive markers
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2014 (English)In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 17, no 2, p. 97-102Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
3D motion capture system, Active filtering, Outdoor, Ski-cross, Snow
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:miun:diva-20919 (URN)10.1007/s12283-013-0140-0 (DOI)2-s2.0-84900512574 (Scopus ID)
Projects
Swedish Winter Sports Research Centre
Note

Published online 11 Oct 2013.

Available from: 2014-01-01 Created: 2014-01-01 Last updated: 2017-12-06Bibliographically approved
Ferdinands, R. E., Kersting, U. & Marshall, R. N. (2013). A twenty-segment kinematics and kinetics model for analysing golf swing mechanics. Sports Technology, 6(4), 184-201
Open this publication in new window or tab >>A twenty-segment kinematics and kinetics model for analysing golf swing mechanics
2013 (English)In: Sports Technology, ISSN 1934-6190, Vol. 6, no 4, p. 184-201Article in journal (Refereed) Published
Abstract [en]

The golf swing is a complex, multi-planar, three-dimensional (3D) motion sequence performed at very high speeds. These properties make biomechanical analysis of the golf swing difficult. Hence, the aim of this study was to develop a computer model of the golf swing capable of calculating a diverse range of 3D kinematics and kinetics values based on motion analysis data collected in the laboratory. Five golfers performed six swings in the field of view of eight Falcon High Speed Resolution cameras (240 Hz), which captured the movements of 56 markers placed on the golfers and their clubs, resulting in marker trajectories that were processed into linear xyz-coordinates using the Eva Motion Analysis system. To perform the kinematics and kinetics calculations, a 20-segment rigid body model of the human body was designed in the Mechanical Systems Pack, connecting the segments by a selection of linear and spherical constraints, resulting in a system of segments with 58 degrees of freedom, with the constraint equations of motion calculated by the Newton-Lagrangian iteration method. The model allowed for the derivation of segmental sequencing, separation angles, segmental planes of motion, segmental velocity contributions, joint torques and muscle powers. The preliminary data suggest that such an integrated kinematics and kinetics analysis is necessary to understand the mechanical complexity of golf swing. Even with the small sample size analysed in this study, some interesting trends were found, such as certain violations of the classical proximal-to-distal sequencing scheme, differing swing plane and club head trajectories in the backswing and downswing phases, minimal hip angular velocity contribution to the ball at impact, concentric and eccentric muscle powers in the downswing phase, and increased lumbar loading factors from the mid-downswing phase to ball impact. © 2014 Taylor & Francis.

Keywords
biomechanics, golf model, golf swing, kinematics, kinetics
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-22042 (URN)10.1080/19346182.2013.854799 (DOI)2-s2.0-84899032321 (Scopus ID)
Note

Language of Original Document: English

Available from: 2014-06-02 Created: 2014-05-30 Last updated: 2014-06-02Bibliographically approved
Nedergaard, N. J., Heinen, F., Sloth, S., Holmberg, H.-C. & Kersting, U. (2013). Biomechanical characteristics of the start in ski cross. In: Proceedings for the 6th International Congress on Science and Skiing: . Paper presented at 6th International Congress on Science and Skiing (pp. 101).
Open this publication in new window or tab >>Biomechanical characteristics of the start in ski cross
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2013 (English)In: Proceedings for the 6th International Congress on Science and Skiing, 2013, p. 101-Conference paper, Oral presentation with published abstract (Refereed)
National Category
Medical and Health Sciences Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-20941 (URN)978-3-200-03417-4 (ISBN)
Conference
6th International Congress on Science and Skiing
Available from: 2014-01-02 Created: 2014-01-02 Last updated: 2014-01-03Bibliographically approved
Nedergaard, N. J., Heinen, F., Sloth, S., Holmberg, H.-C. & Kersting, U. (2013). Is there an influence of start slope inclination on movement and force patterns in ski cross starts?. In: Erich Mueller, Josef Kröll, Stefan Josef Lindinger, Jurgen Pfusterschmied, Thomas Stöggl (Ed.), Proceedings for the 6th International Congress on Science and Skiing: . Paper presented at 6th International Congress on Science and Skiing (pp. 153).
Open this publication in new window or tab >>Is there an influence of start slope inclination on movement and force patterns in ski cross starts?
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2013 (English)In: Proceedings for the 6th International Congress on Science and Skiing / [ed] Erich Mueller, Josef Kröll, Stefan Josef Lindinger, Jurgen Pfusterschmied, Thomas Stöggl, 2013, p. 153-Conference paper, Oral presentation with published abstract (Refereed)
National Category
Medical and Health Sciences Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-20944 (URN)978-3-200-03417-4 (ISBN)
Conference
6th International Congress on Science and Skiing
Available from: 2014-01-02 Created: 2014-01-02 Last updated: 2014-01-02Bibliographically approved
Kersting, U. G., Ferdinands,, R. E. .. & Marshall, R. N. (2013). Kinematic and kinetic energy analysis of segmental sequencing in cricket fast bowling. Sports Technology, 6(1), 10-21
Open this publication in new window or tab >>Kinematic and kinetic energy analysis of segmental sequencing in cricket fast bowling
2013 (English)In: Sports Technology, ISSN 1934-6182, E-ISSN 1934-6190, Vol. 6, no 1, p. 10-21Article in journal (Refereed) Published
Abstract [en]

Although there have been many studies to quantify the segmental sequencing in other sports, there has been little such research applied to cricket bowling. In this study, 34 fast bowlers (22.3 ± 3.7 years) of premier grade level and above were tested using 3D motion analysis, their balls speed ranging from 27.0 to 35.6 m s− 1. One-way repeated measures ANOVA was used to test for within-participant differences in segmental sequencing based on the timings of maximum segmental angular velocities and kinetic energies, the data showing that bowlers exhibited a general order of proximal-to-distal sequencing. Bivariate Pearson's product-movement correlation coefficients were calculated to assess the relationships between kinematic variables and ball release speed, yielding a set of variables for entry into a stepwise multiple regression model. The multiple regression model with the sequential timing variables of thoracic linear kinetic energy (KE), upper-arm circumduction velocity and forearm rotation KE, as well as the pelvic–shoulder separation acceleration accounted for 55% of the variability in ball speed (R 2 = 0.55, adjusted R 2 = 0.49, F(4, 29) = 8.86, p < 0.001). This study showed that both the magnitude and the timing of segmental activation are important to generate ball speed in fast bowling.

Place, publisher, year, edition, pages
Routledge, 2013
Keywords
cricket, bowling, segmental sequencing, segmental timing, biomechanics, kinematics
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-18411 (URN)10.1080/19346182.2012.737800 (DOI)2-s2.0-84893201232 (Scopus ID)
Available from: 2013-02-01 Created: 2013-02-01 Last updated: 2017-12-06Bibliographically approved
Kersting, U. G. & Kurpiers, N. (2012). Die Auswirkung einer Skischuhmodifizierung auf Kniegelenksbelastungen im Buckelpistenskilauf. (21ed.). In: Bach, Ingrid (Ed.), Schriftenreihe der ASH (pp. 140-150). Hamburg: Feldhaus Verlag
Open this publication in new window or tab >>Die Auswirkung einer Skischuhmodifizierung auf Kniegelenksbelastungen im Buckelpistenskilauf.
2012 (German)In: Schriftenreihe der ASH / [ed] Bach, Ingrid, Hamburg: Feldhaus Verlag , 2012, 21, p. 140-150Chapter in book (Refereed)
Place, publisher, year, edition, pages
Hamburg: Feldhaus Verlag, 2012 Edition: 21
Series
Schriftenreihe der ASH, ISSN 0949-9296 ; 21
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-18412 (URN)
Available from: 2013-02-01 Created: 2013-02-01 Last updated: 2013-02-05Bibliographically approved
Kurpiers, N., McAlpine, P. R. & Kersting, U. (2009). Perspectives for Comprehensive Biomechanical Analyses in Mogul Skiing. Research in Sports Medicine: An International Journal, 17(4), 231-244
Open this publication in new window or tab >>Perspectives for Comprehensive Biomechanical Analyses in Mogul Skiing
2009 (English)In: Research in Sports Medicine: An International Journal, ISSN 1543-8627, E-ISSN 1543-8635, Vol. 17, no 4, p. 231-244Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to examine the effects of using aforce measurement device on riding technique in mogul skiing. Amock-up version of such a device was positioned between ski bootand binding. Data on three-dimensional kinematics and perceptionwere collected for eight subjects skiing down a mogul course.Parameters analysed were knee angle, side and forward lean ofthe trunk and hip, and the path of the body’s centre of mass. A perceptionquestionnaire was used on selective aspects to assess theskiers’ perception of the performances. Perception ratings showedno significant detrimental effects. All assessed components showeda trend of improvement from the first to last run, thus suggestingfamiliarisation was achieved. Kinematic analysis revealed that nosignificant alterations occurred. In conclusion, it is intended toutilise a functional force plate similar to the one presented byKiefmann et al. (2006) for future studies in freestyle skiing.

Place, publisher, year, edition, pages
London: Taylor & Francis, 2009
Keywords
mogul skiing, kinematics, force measurement, mock-up
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-16552 (URN)10.1080/15438620903321037 (DOI)
Available from: 2012-06-25 Created: 2012-06-25 Last updated: 2017-12-07Bibliographically approved
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