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Halvorsen, Kjartan
Publications (10 of 20) Show all publications
Nilsson, J., Tinmark, F., Halvorsen, K. & Arndt, A. (2013). Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing. European Journal of Applied Physiology, 113(6), 1385-1394
Open this publication in new window or tab >>Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing
2013 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 6, p. 1385-1394Article in journal (Refereed) Published
Abstract [en]

This study incorporated variations in speed and the horizontal resistance acting upon elite female skiers during double poling (DP) on a treadmill and specifically analyzed biomechanical adaptations to these variations. Whole body kinematics and pole force data were recorded and used to calculate the moment of force acting on the shoulder and elbow joints. Data were obtained with a 3D optoelectronic system using reflective markers at given anatomical landmarks. Forces along the long axis of the right pole were measured with a piezoelectric force transducer. Surface electrodes were used to record EMG activity in the rectus femoris, rectus abdominis, latissimus dorsi and triceps brachii muscles. In a first set of recordings, the participants double poled with zero elevation at five different speeds from 8 to 17 km h−1. In a second set of recordings, horizontal resistance was added by weights (0.4–1.9 kg) attached to a pulley system pulling the skier posteriorly during DP at 14 km h−1. Results showed increasing relative duration of the thrust phase with increasing resistance, but not with speed. Significant kinematic differences occurred with increase in both speed and resistance. The mean (±SD) horizontal force components ranged between 1.7 (±1.3) and 2.8 (±1.1) percent (%) bodyweight (BW) in the speed adaptation and 3.1 (±0.6) and 4.0 (±1.3) % BW in the adaptation to horizontal resistance. Peak muscle activity showed a central to peripheral (proximo-distal) activation sequence. The temporal cycle phase pattern in the adaptation to speed and horizontal resistance differed.

National Category
Biological Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2603 (URN)10.1007/s00421-012-2568-5 (DOI)
Available from: 2013-01-04 Created: 2013-01-04 Last updated: 2018-06-07Bibliographically approved
Ekblom, M., Ovendal, A., Tais, S., Halvorsen, K. & Eriksson, M. (2012). Acute effects of concurrent EMG feedback on knee extensor strength and activation. Paper presented at XIX Biennial Conference of the International Society of Electrophysiology and Kinesiology, 19-21 July, 2012, Brisbane, Australia.
Open this publication in new window or tab >>Acute effects of concurrent EMG feedback on knee extensor strength and activation
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2012 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Medical and Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2502 (URN)
Conference
XIX Biennial Conference of the International Society of Electrophysiology and Kinesiology, 19-21 July, 2012, Brisbane, Australia
Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2017-03-10Bibliographically approved
Tarassova, O., Halvorsen, K., Åberg, A. C. & Ekblom, M. (2012). Balance mechanisms in children with and without motor coordination difficulties. In: Balance mechanisms in children with and without motor coordination difficulties. Paper presented at International Society for Posture and Gait Research Conference, 24-28 June, 2012, Trondheim, Norway..
Open this publication in new window or tab >>Balance mechanisms in children with and without motor coordination difficulties
2012 (English)In: Balance mechanisms in children with and without motor coordination difficulties, 2012Conference paper, Oral presentation with published abstract (Refereed)
National Category
Medical and Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2500 (URN)
Conference
International Society for Posture and Gait Research Conference, 24-28 June, 2012, Trondheim, Norway.
Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2016-08-09Bibliographically approved
Tinmark, F., Hellström, J., Arndt, A. & Halvorsen, K. (2012). Contributions to club velocity in golf swings to submaximal and maximal shot distances. In: Bradshaw, E.J., Burnett, A., Hume, P.A. (Ed.), eProceedings of the 30th Conference of the International Society of Biomechanics in Sports, 2012: Volume 3. Paper presented at The 30th Conference of the International Society of Biomechanics in Sports, Melbourne, Australia, July 02 – July 06, 2012 (pp. 81-83).
Open this publication in new window or tab >>Contributions to club velocity in golf swings to submaximal and maximal shot distances
2012 (English)In: eProceedings of the 30th Conference of the International Society of Biomechanics in Sports, 2012: Volume 3 / [ed] Bradshaw, E.J., Burnett, A., Hume, P.A., 2012, p. 81-83Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The contribution of joint rotations to endpoint velocity was investigated in golf shots to submaximal and maximal shot distances using a 41degrees of freedom (DOF) kinematic model. A subset of 16 DOFs was found to explain 97%-99% of endpoint velocity regulation at club–ball contact. The largest contributors, for both groups at every shot condition, were pelvis and torso twist rotation among the most proximal DOFs, elbow pronation/supination and wrist flexion/extension among DOFs in the left arm, and shoulder internal/external rotation and wrist flexion/extension among DOFs in the right arm. The contributions from pelvis obliquity, left wrist flexion/extension, left wrist ulnar/radial deviation and right shoulder flexion/extension differed significantly between the advanced and intermediate group.

National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2567 (URN)
Conference
The 30th Conference of the International Society of Biomechanics in Sports, Melbourne, Australia, July 02 – July 06, 2012
Available from: 2012-12-19 Created: 2012-12-19 Last updated: 2018-06-07Bibliographically approved
Tais, S., Eriksson, M., Halvorsen, K. & Ekblom, M. (2012). Effects of training with concurrent EMG feedback on Quadriceps stength and activation. Paper presented at The XIX Biennial Conference of the International Society of Electrophysiology and Kinesiology, 19-21 July, 2012, Brisbane, Australia.
Open this publication in new window or tab >>Effects of training with concurrent EMG feedback on Quadriceps stength and activation
2012 (English)Conference paper, Published paper (Refereed)
National Category
Medical and Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2503 (URN)
Conference
The XIX Biennial Conference of the International Society of Electrophysiology and Kinesiology, 19-21 July, 2012, Brisbane, Australia
Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2016-04-01Bibliographically approved
Åberg, A. C., Thorstensson, A., Tarassova, O. & Halvorsen, K. (2011). Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: A reliability study.. Gait & Posture, 34(3), 352-7
Open this publication in new window or tab >>Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: A reliability study.
2011 (English)In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 3, p. 352-7Article in journal (Refereed) Published
Abstract [en]

For older people balance control in standing is critical for performance of activities of daily living without falling. The aims were to investigate reliability of quantification of the usage of the two balance mechanisms M1 ‘moving the centre of pressure’ and M2 ‘segment acceleration’ and also to compare calculation methods based on a combination of kinetic (K) and kinematic (Km) data, (K–Km), or Km data only concerning M2. For this purpose nine physically fit persons aged 70–78 years were tested in narrow and single-leg standing. Data were collected by a 7-camera motion capture system and two force plates. Repeated measure ANOVA and Tukey's post hoc tests were used to detect differences between the standing tasks. Reliability was estimated by ICCs, standard error of measurement including its 95% CI, and minimal detectable change, whereas Pearson's correlation coefficient was used to investigate agreement between the two calculation methods. The results indicated that for the tasks investigated, M1 and M2 can be measured with acceptable inter- and intrasession reliability, and that both Km and K–Km based calculations may be useful for M2, although Km data may give slightly lower values. The proportional M1:M2 usage was approximately 9:1, in both anterio-posterior (AP) and medio-lateral (ML) directions for narrow standing, and about 2:1 in the AP and of 1:2 in the ML direction in single-leg standing, respectively. In conclusion, the tested measurements and calculations appear to constitute a reliable way of quantifying one important aspect of balance capacity in fit older people.

Keywords
Balance, Elderly, Assessment, Reliability
National Category
Medical and Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2065 (URN)10.1016/j.gaitpost.2011.05.025 (DOI)
Available from: 2012-01-06 Created: 2012-01-06 Last updated: 2018-03-09Bibliographically approved
Tinmark, F., Hellström, J., Halvorsen, K. & Thorstensson, A. (2010). Elite golfers' kinematic sequence in full-swing and partial-swing shots. Sports Biomechanics, 9(4), 236-244
Open this publication in new window or tab >>Elite golfers' kinematic sequence in full-swing and partial-swing shots
2010 (English)In: Sports Biomechanics, ISSN 1476-3141, Vol. 9, no 4, p. 236-244Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to investigate whether kinematic proximal-to-distal sequencing (PDS) and speed-summation are common characteristics of both partial and full-swing shots in golf players of different skill levels and genders. A total of 45 golfers participated, 11 male tournament professionals, 21 male and 13 female elite amateurs. They performed partial shots with a wedge to targets at three submaximal distances, 40, 55 and 70 m, and full-swing shots with a 5 iron and a driver for maximal distance. Pelvis, upper torso and hand movements were recorded in 3D with an electromagnetic tracking system (Polhemus Liberty) at 240 Hz and the magnitude of the resultant angular velocity vector of each segment was computed. The results showed a significant proximal-to-distal temporal relationship and a concomitant successive increase in maximum (peak) segment angular speed in every shot condition for both genders and levels of expertise. A proximal-to-distal utilization of interaction torques is indicated. Using a common PDS movement strategy in partial and full-swing golf shots appears beneficial from mechanical and control points of view and could serve the purpose of providing both high speed and accuracy.

National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-1628 (URN)10.1080/14763141.2010.535842 (DOI)
Available from: 2010-12-13 Created: 2010-12-13 Last updated: 2018-06-07Bibliographically approved
Åberg, A. C., Frykberg, G. E. & Halvorsen, K. (2010). Medio-lateral stability of sit-to-walk performance in older individuals with and without fear of falling.. Gait & Posture, 31(4), 438-43
Open this publication in new window or tab >>Medio-lateral stability of sit-to-walk performance in older individuals with and without fear of falling.
2010 (English)In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 31, no 4, p. 438-43Article in journal (Refereed) Published
Abstract [en]

Most falls in older people are due to loss of balance during everyday locomotion, e.g., when initiating walking from sitting; sit-to-walk (STW). It has been considered that the broader stride width in walking that is seen in many people with fear of falling (FoF) does not increase stability, but could be predictive of future falls because of increased medio-lateral (ML) velocity of the body centre of mass (CoM). This study was aimed to examine step-, velocity- and stability-related parameters, focusing on ML stability, in STW performance of people with and without FoF. Ten subjects with FoF and 10 matched controls, aged > or = 70 years, were included. Kinematic and kinetic data were collected in a laboratory. Stability parameters were calculated from a formula implying that the vertical projection of the CoM extrapolated by adding its velocity times a factor radicall/g (height of inverted pendulum divided by gravity) should fall within the base of support (BoS). A related spatial margin of stability (SMoS), defined as the minimum distance from the extrapolated CoM (XCoM) to the boundaries of the BoS, was also calculated. In the phase 'seat-off-second-toe-off', the FoF group had significantly (p<0.05) shorter and broader steps, lower forward but similar ML CoM velocity, and broader CoM and XCoM widths. The FoF group therefore exhibited a disproportionately large sideways velocity compared to the controls. This indicates that STW may be a hazardous transfer for older people with FoF, which should be relevant in assessment and training aimed at preventing falls.

National Category
Medical and Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-1632 (URN)10.1016/j.gaitpost.2010.01.018 (DOI)20189390 (PubMedID)
Available from: 2010-12-14 Created: 2010-12-14 Last updated: 2017-12-11Bibliographically approved
Forsell, C. & Halvorsen, K. (2009). A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum.. Journal of Biomechanics, 42(3), 361-5
Open this publication in new window or tab >>A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum.
2009 (English)In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 42, no 3, p. 361-5Article in journal (Refereed) Published
Abstract [en]

A new method is proposed for finding small sets of points on the body giving sufficient information for estimating the whole body center of mass (CoM), as well as the linear momenta (LM) and angular momenta (AM). In the underlying model each point (whose trajectory is tracked by a marker) is a point mass: Hence the body is represented by a simple system of point masses. The first step is to determine the appropriate set of points and the mass of each point, which is assumed to be specific for the movement performed. The distribution of the mass to each marker is determined from training data for which the true (or reference) trajectories of the CoM, LM or AM are known. This leads to a quadratic optimization problem with inequality constraints. The use of the method is demonstrated on data from discus throw. Results indicate reasonably small errors, considering the magnitude of other error sources, in CoM position (average magnitude of estimation error 1-2cm), and moderate errors in AM (13-20% of peak value).

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:gih:diva-985 (URN)10.1016/j.jbiomech.2008.10.029 (DOI)19100983 (PubMedID)
Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2017-12-13Bibliographically approved
Gullstrand, L., Halvorsen, K., Tinmark, F., Eriksson, M. & Nilsson, J. (2009). Measurements of vertical displacement in running, a methodological comparison.. Gait & posture, 30(1), 71-75
Open this publication in new window or tab >>Measurements of vertical displacement in running, a methodological comparison.
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2009 (English)In: Gait & posture, ISSN 1879-2219, Vol. 30, no 1, p. 71-75Article in journal (Refereed) Published
Abstract [en]

The aim was (1) to evaluate measurements of vertical displacements (V(disp)) of a single point on sacrum as an estimate of the whole body centre of mass (CoM) V(disp) during treadmill running and (2) to compare three methods for measuring this single point. These methods were based on a position transducer (PT), accelerometers (AMs) and an optoelectronic motion capture system. Criterion method was V(disp) of the whole body CoM measured with the motion capture system. Thirteen subjects ran at 10, 12, 14, 16, 18, 20 and 22kmh(-1) with synchronous recordings with the three methods. Four measurements of the (V(disp)) were derived: (1) V(disp) of CoM calculated from a segment model consisting of 13 segments tracked with 36 reflective markers, (2) V(disp) of the sacrum recorded with the PT, (3) V(disp) of the sacrum calculated from the AM, and (4) V(disp) of the sacrum calculated as the mid point of two reflective markers (sacrum marker, SM) attached at the level of the sacral bone. The systematic discrepancy between the measurements of sacrum V(disp) and CoM V(disp) varied between 0 and 1.5mm and decreased with increasing running velocity and decreasing step duration. PT and SM measurements showed strong correlation, whereas the AM showed a variability increasing with velocity. The random discrepancy within each subject was 7mm for all three methods. In conclusion single-point recordings of the sacrum V(disp) may be used to monitor changes in V(disp) of CoM during treadmill running.

National Category
Medical and Health Sciences Sport and Fitness Sciences
Identifiers
urn:nbn:se:gih:diva-871 (URN)10.1016/j.gaitpost.2009.03.001 (DOI)19356933 (PubMedID)
Available from: 2009-04-10 Created: 2009-04-10 Last updated: 2018-06-07Bibliographically approved
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