| 1. |
- Bjerkefors, Anna, 1966-, et al.
(författare)
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Seated Double-Poling Ergometer Performance of Individuals with Spinal Cord Injury - A New Ergometer Concept for Standardized Upper Body Exercise
- 2013
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Ingår i: International Journal of Sports Medicine. - : Georg Thieme Verlag KG. - 0172-4622 .- 1439-3964. ; 34:2, s. 176-182
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to evaluate biomechanics during seated double-poling exercises in individuals with spinal cord injury (SCI) and to compare these with those of able-bodied persons (AB). 26 participants volunteered for the study; 13 with SCI (injury levels C7-T12), and 13 AB. A seated double-poling ergometer (SDPE) was developed. 3-dimensional kinematics was measured and piezoelectric force sensors were used to register force in both poles for calculation of power during incremental intensities. Significantly lower power outputs, (143.2 ± 51.1 vs. 198.3 ± 74.9 W) and pole forces (137.1 ± 43.1 vs. 238.2 ± 81.2 N) were observed during maximal effort in SCI compared to AB. Sagittal upper trunk range of motion increased with intensity and ranged from 6.1–34.8 ° for SCI, and 6.9–31.3 ° for AB, with larger peak amplitudes in flexion for AB (31.4 ± 12.9 °) compared to SCI (10.0 ± 8.0 °). All subjects with SCI were able to exercise on the SDPE. Upper body kinematics, power and force outputs increased with intensity in both groups, but were in general, lower in SCI. In conclusion, the SDPE could be successfully used at low to high work intensities enabling both endurance and strength training for individuals with SCI
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| 2. |
- Carlsson, Magnus, et al.
(författare)
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The effect of ball temperature on ball speed and carry distance in golf drives
- 2018
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part P. - London, UK : Sage Publications. - 1754-3371. ; 233:2, s. 186-192
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the effect of ball temperature on impact ball speed and carry distance during golf drives in a blind randomized test design. The balls were exposed to a temperature-controlled environment (4 °C, 18 °C, 32 °C, and 46 °C) for 24 h prior to the test and each temperature group consisted of 30 balls. The 120 drives were performed by an elite male golfer (handicap: 0.0) in an indoor driving range. All drives were measured by a Doppler-radar system to determine the club-head speed, launch angle, spin rate, ball speed, and carry distance. Differences between the groups were investigated using a one-way analysis of variance. The results indicated that ball-speed and carry-distance differences occurred within the four groups (p < 0.001 and p < 0.01, respectively). The post hoc analyses showed that the ball temperatures of 18 °C and 32 °C had greater ball speeds and carry distances than balls at 4 °C and 46 °C (all p < 0.05). The intervals for the between-group differences were 0.6–0.7 m s –1 and 2.9–3.9 m for ball speed and carry distance, respectively. Hence, the results showed that ball temperature influences both the ball speed and the carry distance. Based on the findings in this study, standardization of ball temperature should be factored into governing body regulation tests for golf equipment. © IMechE 2018.
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| 3. |
- Carlsson, Tomas, et al.
(författare)
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The effect of ball temperature on ball speed and carry distance in golf drives
- 2018
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Konferensbidrag (refereegranskat)abstract
- THE EFFECT OF BALL TEMPERATURE ON BALL SPEED AND CARRY DISTANCE IN GOLF DRIVESCarlsson, T.1, Nilsson, J.1,2, Hellström, J.3, Tinmark, F.2, Carlsson, M.1. 1: Dalarna University (Falun, Sweden), 2: The Swedish School of Sport and Health Sciences (Stockholm, Sweden), 3: The Swedish Golf Federation (Stockholm, Sweden). IntroductionPreviously it was reported that golf-ball temperature has influence on the golf balls’ coefficient of restitution, impact duration, and maximal deformation (Allen et al., 2012). They concluded that their research was the first step in a process for determining the effect of temperature on a golf drive. However, how large influence the golf-ball temperature has on golf drives remains to be investigated. The purpose was to investigate the effect of ball temperature on impact ball speed and carry distance during golf drives in a blind randomized test design. MethodsThe balls were exposed to a temperature-controlled environment (4°C, 18°C, 32°C, and 46°C) for twenty-four hours prior to the test, and each of the four different ball-temperature groups consisted of 30 balls. The 120 drives were performed by an elite male golfer (handicap: 0.0) in an indoor driving range. All drives were measured by a Doppler-radar system to determine club-head speed, launch angle, spin rate, ball speed, and carry distance. Differences between the four ball-temperature groups were investigate using a one-way analysis of variance. ResultsThe results indicate that there are ball-speed and carry-distance differences within the four ball-temperature groups (P < 0.001 and P < 0.01, respectively). The post-hoc analyses showed that the ball temperatures 18°C and 32°C had both greater ball speeds and carry distances compared to the balls in the ball-temperature groups 4°C and 46°C (all P < 0.05); the intervals for the between-group differences were 2.0 to 2.4 km/h and 2.9 to 3.9 m for ball speed and carry distance, respectively.ConclusionThe novel results of the current study show that the ball’s temperature has a significant effect on the ball speed after club-head impact and carry distance for drives performed by an elite golfer. The ball temperatures 18°C and 32°C gave significantly increased ball speeds and carry distances compared to the ball-temperature groups 4°C and 46°C. This knowledge could be used to maximise the carry distance and/or to minimise the carry-distance variability related to ball temperature.REFERENCES:Allen T, Bowley A, Wood P, Henrikson E, Morales E, James D. (2012) Procedia Eng, 34, 634-639.
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| 4. |
- Cedervall, Ylva, et al.
(författare)
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Timed Up-and-Go Dual-Task Testing in the Assessment of Cognitive Function : A Mixed Methods Observational Study for Development of the UDDGait Protocol
- 2020
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 17:5
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Tidskriftsartikel (refereegranskat)abstract
- New methods to screen for and identify early-stage dementia disorders are highly sought after. The purpose of this pilot study is to develop a study protocol for a dual-task test aimed at aiding the early detection of dementia disorders. We used the Timed Up-and-Go (TUG) test, which is a mobility task involving starting in a sitting position, standing up, walking three meters to cross a line on the floor, turning around, walking back and sitting down again. We combined TUG with the verbal task of naming different animals. Pilot study participants were 43 individuals with and without established dementia diagnoses who attended a clinic for memory assessment. Video-recorded test performances were systematically analysed. Deviant test performances concerning the interplay between test administration and participants' responses to the assessment instructions were revealed and led to refinements being made to the final study protocol. Exploration of the dual-task test outcome measures in a sub-sample of 22 persons, ten with and twelve without dementia, indicated that step-length and number of named animals after the turning point of the dual-task test might constitute appropriate measures for examining this kind of sample. We concluded that the refined study protocol is feasible for testing individuals undergoing initial memory assessments and healthy controls. Follow-up studies with larger samples are being carried out and will bring new knowledge to this area of research. It may also provide an opportunity for further studies exploring possibilities for broad clinical implementation.
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| 5. |
- Gullstrand, Lennart, et al.
(författare)
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Measurements of vertical displacement in running, a methodological comparison
- 2009
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 30:1, s. 71-75
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Tidskriftsartikel (refereegranskat)abstract
- 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 22 km h(-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 markets, (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 markets (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 1.5 mm 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 7 mm 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.
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| 6. |
- Halvorsen, Kjartan, et al.
(författare)
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Minimal marker set for center of mass estimation in running
- 2009
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 30:4, s. 552-555
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to study the validity of a recently proposed method [Forsell C, Halvorsen K. A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum. journal of Biomechanics 2009;42(3):361-5] for estimating the trajectory of the whole-body center of mass (CoM) in the case of running at: velocities ranging from 10 to 22 km h(-1). The method gives an approximation to the CoM using the position of fewer markers on the body than the standard method of tracking each segment of the body. Fourteen male athletes participated. A standard method for determining the CoM from a model of 13 segments and using the position of 36 markers was used as reference method. Leave-one-out cross-validation revealed errors that decreased with increasing number of markers used in the approximative method. Starting from four markers, the error in absolute position of the CoM decreased from 15 mm to 3 mm in each direction. For the velocity of the CoM the estimation bias was neglectable, and the random error decreased from 0.15 to 0.05 m s(-1). The inter-subject and intra-subject variability in the estimated model parameters increased with increasing number of markers. The method worked well also when applied to running at velocities outside the range of velocities in the data used to determine the model parameters. The results indicate that a model using 10 markers represents a good trade-off between simplicity and accuracy, but users must take into account requirements of their specific applications.
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| 7. |
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| 8. |
- Halvorsen, Kjartan, et al.
(författare)
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The concept of mobility in single- and double handed manipulation.
- 2014
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 47:14, s. 3569-3573
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Tidskriftsartikel (refereegranskat)abstract
- The concept of mobility describes an important property of the human body when performing manipulation tasks. It describes, in a sense, how easy it is to accelerate a link or a point on the manipulator. Most often it is calculated for the end-link or end-point of the manipulator, since these are important for the control objective of the manipulator. Mobility is the inverse of the inertia experienced by a force acting on the end-point, or a combined force and torque acting on the end-link. The concept has been used in studies of reaching tasks with one arm, but thus far not for bi-manual manipulation. We present here the concept for both single-handed and double-handed manipulation, in a general manner which includes any type of grip of the hands on the object. The use of the concept is illustrated with data on the left and right arm in a golf swing.
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| 9. |
- Kvist, Alexander, et al.
(författare)
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Validation of algorithms for calculating spatiotemporal gait parameters during continuous turning using lumbar and foot mounted inertial measurement units
- 2024
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Ingår i: Journal of Biomechanics. - : Elsevier. - 0021-9290 .- 1873-2380. ; 162
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Tidskriftsartikel (refereegranskat)abstract
- Spatiotemporal gait parameters such as step time and walking speed can be used to quantify gait performance and determine physical function. Inertial measurement units (IMUs) allow for the measurement of spatiotemporal gait parameters in unconstrained environments but must be validated against a gold standard.While many IMU systems and algorithms have been validated during treadmill walking and overground walking in a straight line, fewer studies have validated algorithms during more complex walking conditions such as continuous turning in different directions.This study explored the concurrent validity in a population of healthy adults (range 26–52 years) of three different algorithms using lumbar and foot mounted IMUs to calculate spatiotemporal gait parameters: two methods utilizing an inverted pendulum model, and one method based on strapdown integration. IMU data was compared to a Vicon twelve-camera optoelectronic system, using data collected from 9 participants performing straight walking and continuous walking trials at different speeds, resulting in 162 walking trials in total. Intraclass correlation coefficients (ICCa,1) for absolute agreement were calculated between the algorithm outputs and Vicon output.Temporal parameters were comparable in all methods and ranged from moderate to excellent, except double support time which was poor. Strapdown integration performed better for estimating spatial parameters than pendulum models during straight walking, but worse during turning. Selecting the most appropriate model should take into consideration both speed and walking condition.
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| 10. |
- Nilsson, Johnny, et al.
(författare)
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Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing
- 2013
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 113:6, s. 1385-1394
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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