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Danvind, Jonas
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Publications (10 of 14) Show all publications
Lund Ohlsson, M., Danvind, J. & Holmberg, L. J. (2018). Shoulder and Lower Back Joint Reaction Forces in Seated Double Poling. Journal of Applied Biomechanics, 34(5), 369-376
Open this publication in new window or tab >>Shoulder and Lower Back Joint Reaction Forces in Seated Double Poling
2018 (English)In: Journal of Applied Biomechanics, ISSN 1065-8483, E-ISSN 1543-2688, Vol. 34, no 5, p. 369-376Article in journal (Refereed) Published
Abstract [en]

Overuse injuries in the shoulders and lower back are hypothesized to be common in cross-country sit-skiing. Athletes with reduced trunk muscle control mainly sit with the knees higher than the hips (KH). To reduce spinal flexion, a position with the knees below the hips (KL) was enabled for these athletes using a frontal trunk support. The aim of the study was to compare the shoulder joint (glenohumeral joint) and L4-L5 joint reactions of the KL and KH sitting positions. Five able-bodied female athletes performed submaximal and maximal exercise tests in the sitting positions KL and KH on a ski ergometer. Measured pole forces and 3-dimensional kinematics served as input for inverse-dynamics simulations to compute the muscle forces and joint reactions in the shoulder and L4-L5 joint. This was the first musculoskeletal simulation study of seated double poling. The results showed that the KH position was favorable for higher performance and decreased values of the shoulder joint reactions for female able-bodied athletes with full trunk control. The KL position was favorable for lower L4-L5 joint reactions and might therefore reduce the risk of lower back injuries. These results indicate that it is hard to optimize both performance and safety in the same sit-ski.

Keywords
musculoskeletal modeling, inverse-dynamic simulations, muscular metabolic power, cross-country sit-skiing
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-32813 (URN)10.1123/jab.2017-0281 (DOI)000448161700004 ()29651902 (PubMedID)2-s2.0-85055597043 (Scopus ID)
Note

Forskningsfinansiärer

Stiftelsen Promobilia

Rolf & Gunilla Enströms stiftelse

Available from: 2018-02-08 Created: 2018-02-08 Last updated: 2018-12-07Bibliographically approved
Roos, S., Rännar, L.-E., Koptioug, A. & Danvind, J. (2017). Characterization of 316ln lattice structures fabricated via electron beam melting. In: Materials Science and Technology Conference and Exhibition 2017, MS and T 2017: . Paper presented at Materials Science and Technology Conference and Exhibition 2017, MS and T 2017, Pittsburgh, United States, 8 October 2017 through 12 October 2017 (pp. 336-343). Association for Iron and Steel Technology, AISTECH
Open this publication in new window or tab >>Characterization of 316ln lattice structures fabricated via electron beam melting
2017 (English)In: Materials Science and Technology Conference and Exhibition 2017, MS and T 2017, Association for Iron and Steel Technology, AISTECH , 2017, p. 336-343Conference paper, Published paper (Refereed)
Abstract [en]

One of the promising application areas of additive manufacturing (AM) relates to light weight structures, including complex near net shape geometries and lattices. So far one of the limiting factors hampering wider industrial usage of AM technologies is the limited availability of processed materials. The aim of present study was to expand the previous success in electron beam melting (EBM®) manufacturing of 316LN bulk materials into thinner lattice structures thus further widening the application areas available for the method. Present paper reports on the initial results where lattice structures with octagonal basic cells were manufactured using EBM® and characterized using microscopy and compression testing. 

Place, publisher, year, edition, pages
Association for Iron and Steel Technology, AISTECH, 2017
Keywords
316l, Additive manufacturing, Electron beam melting, Lattice, Net structures
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-32865 (URN)10.7449/2017/MST_2017_336_343 (DOI)2-s2.0-85041185273 (Scopus ID)9781510850583 (ISBN)
Conference
Materials Science and Technology Conference and Exhibition 2017, MS and T 2017, Pittsburgh, United States, 8 October 2017 through 12 October 2017
Available from: 2018-02-20 Created: 2018-02-20 Last updated: 2018-02-20Bibliographically approved
Lund Ohlsson, M., Danvind, J. & Holmberg, L. J. (2017). LUMBAR SPINE REACTION FORCES IN SEATED PARA-SPORT: CROSS-COUNTRY SIT-SKIING. In: Brisbane 2017: Abstract book. Paper presented at XXVI Congress of the International Society of Biomechanics, Brisbane, Australia, 23-27 July 2017..
Open this publication in new window or tab >>LUMBAR SPINE REACTION FORCES IN SEATED PARA-SPORT: CROSS-COUNTRY SIT-SKIING
2017 (English)In: Brisbane 2017: Abstract book, 2017Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

INTRODUCTION

For wheel-chair users shoulder injuries [1] and lower back injuries [2] are common. Lower back kyphosis of the spine, increases the anterior shear force in the lower back [3] and increases the risk of shoulder injuries [4].

 

Cross-country sit-skiing (CCSS) is an endurance sport where the athlete is seated in a sledge mounted on a pair of skis and propel themselves by poling with a pair of sticks. This sport creates more equal loading on the muscles around the shoulder than wheel-chair rolling [5] which is positive in an injury perspective for the gleno-humeral joint [1].

 

Athletes in CCSS with reduced trunk muscle control often sits in a sledge with their knees higher than their hips (KH) and a backrest. This position is hypothesized to be associated with spinal kyphosis and hence an increased risk of injuries. Therefore we have created a new sitting position with knees lower than hips (KL) with the trunk restrained on a frontal support.

 

The aim of this study was to compute the L4/L5 joint reactions and compare the results between the positions KH and KL.

METHODS

Five female abled-bodied cross-country skiing athletes (62.6 ± 8.1kg, 1.67 ± 0.05m)  performed one exercise test session in each sitting position; The sessions included a sub-maximal incremental test, including 4-6 exercise levels of 3 min (exercise intensity nr 4, 37W, reflected race-pace) and a maximal time-trial (MAX) of 3 min on a commercial skiing ergometer (ThoraxTrainer A/S, Denmark).

 

Full-body kinematics (Qualisys AB, Sweden) and pole forces (Biovision, Germany) were measured in 200 Hz. These data served as input to inverse dynamic simulations in The AnyBody Modelling system (AMS 6.0, Anybody Technology A/S, Denmark). For each participant and sitting position, simulations were made for exercise intensity 37W and MAX over four poling cycles using a 5th order polynomial muscle recruitment criteria. Compression forces and anterior shear forces between L4 and L5 were computed and normalized to each participant’s standing joint reactions. Data were compared pair-wise between the two sitting positions.

 

Statistical significance (p ≤ 0.05) were marked with asterisk (*). Tendency of difference (0.05 ≤ p < 0.10) were marked (ǂ).

 

RESULTS AND DISCUSSION

Performance was higher in position KH (KL: 0.77±0.08 W/kg, KH: 1.00±0.14 W/kg, p < 0.01). No difference were observed in cycle length or cycle time. Kinematics results showed that KL had less spine flexion and range of motion in flexion. KH showed higher mean pole force in 37W and tendency of higher peak pole force in MAX.

 

In standing, L4/L5 compression and anterior shear forces were 354 ± 45N and 32 ± 11N respectively. The normalized L4/L5 reaction forces (fig. 1) were larger in KH, especially during MAX intensity due to higher power. For equal power output, 37W, the mean anterior shear force was larger in KH and the mean compression force showed tendency of larger in KH (p=0.077).

 

Figure 1: Normalized joint reaction forces, compression and anterior shear forces, between vertebrae L4/L5 for the two sitting positions KH and KL with trunk restraint. Min – minimal force, Maximal force and Mean – mean force over the four poling cycles.

 

CONCLUSIONS

Based on inverse-dynamics musculo-skeletal simulations of 5 abled-bodied athletes, the sitting position KL with frontal restraint reduced the compression and shear force between the L4/L5 vertebrae but impeded performance. This study shows the difficulty of comparing performance and safety in the same piece of equipment.

 

ACKNOWLEDGEMENTS

The authors acknowledge the Rolf & Gunilla Enström foundation and the Promobilia foundation, Sweden, for financial support, and the Ableway AB (Sweden) for construction of the sledges.

 

REFERENCES

  1. Burnham RS, et al., Am J Sports Med, 21: 238-242, 1993.
  2. Thyberg M, et al., Disabil rehabil. 23:677-682, 2001.
  3. McGill SM, et al., Clin Biomech, 15: 777-780, 2000.
  4. Samuelsson KA, et al., J Rehabil Res Dev, 41: 65-74, 2004.
  5. Bjerkefors A, et al., Int J Sports Med, 34: 176-182, 2013.
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-32191 (URN)
Conference
XXVI Congress of the International Society of Biomechanics, Brisbane, Australia, 23-27 July 2017.
Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2017-12-11Bibliographically approved
Bäckström, M., Carlsson, P., Danvind, J., Koptioug, A., Sundström, D. & Tinnsten, M. (2016). A New Wind Tunnel Facility Dedicated to Sports Technology Research and Development. In: Procedia Engineering: . Paper presented at 11th conference of the International Sports Engineering Association, ISEA 2016, 11 July 2016 through 14 July 2016 (pp. 62-67). Elsevier, 147
Open this publication in new window or tab >>A New Wind Tunnel Facility Dedicated to Sports Technology Research and Development
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2016 (English)In: Procedia Engineering, Elsevier, 2016, Vol. 147, p. 62-67Conference paper, Published paper (Refereed)
Abstract [en]

It is desirable to test sportswear and sports equipment at exactly the same conditions experienced during use. Although outdoor tests are in many cases the most adequate, they are at the same time quite complex, demand special measurement technology and wearable equipment. Results of such tests are often hard to interpret due to large variations because of rapidly varying ambient conditions and individual specifics of human objects, among other factors, which are hard or impossible to control. One common alternative is provided through indoor tests made in a stable, controlled environment. Controlling such parameters as temperature, wind speed and direction, air humidity with indoor facilities intended to replicate ambient conditions, and designed to house large objects, is a complex undertaking. Furthermore, replicating seasonal conditions complicates matters even more. A significant amount of research and development related to the operation of sports and other related equipment at high speeds and windy conditions has been carried out in wind tunnels with different degrees of climatic realism. However, the majority of such facilities are designed and constructed for the automotive industry, the aerospace industry and for marine research. A new wind tunnel facility, opened in March 2015 at the Sports Tech Research Centre at Mid Sweden University, is currently among the very few facilities in the world designed under the direct control of sports technology specialists and dedicated primarily to research and development within sports, outdoor clothing and footwear as well as equipment development and testing. The main goal when constructing this dedicated facility has been to successfully replicate ambient conditions for training and equipment testing in environments with controlled wind speed, temperature (+4 to +35°C) and precipitation (from fine mist to heavy downfall). The wind tunnel facility houses the largest moving belt in Sweden (5 m long and 2.7 m wide) which can be adjusted for leveled, uphill and downhill motion. The moving belt is placed in a 10 m2 test section in which the wind speed can be adjusted to match belt speed or independently up to 55 km/h (without narrowing the test section). A fog and rain system, mounted in the test section, can generate rainy conditions varying from fine mist to heavy monsoon. It is also possible to open the facility in order to allow experiments to be performed in wide range of outdoor, ambient conditions. This paper presents the basic parameters of the new wind tunnel facility. As this facility is open for wider international cooperation, we also report the general directions of current research and the future work planned to be carried out at this facility.

Place, publisher, year, edition, pages
Elsevier, 2016
Series
Procedia Engineering, ISSN 1877-7058
Keywords
climate control, indoor testing, moving belt, product development, wind tunnel
National Category
Sport and Fitness Sciences Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-28942 (URN)10.1016/j.proeng.2016.06.190 (DOI)000387454000011 ()2-s2.0-84982913097 (Scopus ID)
Conference
11th conference of the International Sports Engineering Association, ISEA 2016, 11 July 2016 through 14 July 2016
Note

Conference Paper

Available from: 2016-09-27 Created: 2016-09-27 Last updated: 2016-12-02Bibliographically approved
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
Lund Ohlsson, M., Danvind, J. & Holmberg, J. (2013). Can Simulations Assist in Classification Development?. In: Equipment and Technology in Paralympic Sports: . Paper presented at VISTA2013 Scientific Conference, Gustav-Stresemann-Institut, Bonn, 1-4 May, 2013. International Paralympic Committee
Open this publication in new window or tab >>Can Simulations Assist in Classification Development?
2013 (English)In: Equipment and Technology in Paralympic Sports, International Paralympic Committee , 2013Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
International Paralympic Committee, 2013
Keywords
Cross-country skiing, Musculoskeletal biomechanics
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-28017 (URN)
Conference
VISTA2013 Scientific Conference, Gustav-Stresemann-Institut, Bonn, 1-4 May, 2013
Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2016-06-30Bibliographically approved
Elmer, S., Danvind, J. & Holmberg, H.-C. (2013). Development of a novel eccentric arm cycle ergometer for training the upper body. Medicine & Science in Sports & Exercise, 45(1), 206-211
Open this publication in new window or tab >>Development of a novel eccentric arm cycle ergometer for training the upper body
2013 (English)In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 45, no 1, p. 206-211Article in journal (Refereed) Published
Abstract [en]

Several investigators have demonstrated that chronic eccentric leg cycling is an effective method for improving lower body neuromuscular function (e.g., quadriceps muscle size, strength, and mobility) in a variety of patient and athletic populations. To date, there are no reports of using eccentricarm cycling (ECarm) as an exercise modality, probably in large part because of the lack of commercially available ECarm ergometers. Purpose: Our purposes for conducting this study were to 1) describe the design and construction of an ECarm ergometer and 2) compare ECarm to traditional concentric arm cycling (CCarm). Methods: All of the parts of a Monark 891E cycle ergometer (Monark Exercise AB, Vansbro, Sweden) were removed, leaving the frame and flywheel. An electric motor (2.2 kW) was connected to the flywheel via a pulley and a belt. Motor speed and pedaling rate were controlled by a variable frequency drive. A power meter quantified power and pedaling rate, and provided feedback to the individual. Eight individuals performed 3-min ECarm and CCarm trials at 40, 80, and 120 W (60 rpm) while V̇O2 was measured. Results: The ECarm ergometer was simple to use, was adjustable, provided feedback on power output to the user, and allowed for a range of eccentric powers. V̇O2 during ECarm was substantially lower compared with CCarm (P < 0.001). At similar V̇O2 (0.97 ± 0.18 vs 0.91 ± 0.09 L•min, for ECarm and CCarm, respectively, P = 0.26), power absorbed during ECarm was approximately threefold greater than that produced during CCarm (118 ± 1 vs 40 ± 1 W, P < 0.001). Conclusion: This novel ECarm ergometer can be used to perform repetitive, high-force, multijoint, eccentric actions with the upper body at a low level of metabolic demand and may allow researchers and clinicians to use ECarm as a training and rehabilitation modality. © 2012 by the American College of Sports Medicine.

Place, publisher, year, edition, pages
Lippincott Williams & Wilkins, 2013
Keywords
Eccentric muscle contraction; ergometry; multijoint exercise; power; rehabilitation
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:miun:diva-18151 (URN)10.1249/MSS.0b013e318269c79c (DOI)000312535200028 ()2-s2.0-84871615327 (Scopus ID)
Available from: 2013-01-08 Created: 2013-01-08 Last updated: 2017-12-06Bibliographically approved
Skoglund, P., Lund Ohlsson, M. & Danvind, J. (2013). Lower Leg Prosthesis for Cross-Country Skiing Classical Technique. In: : . Paper presented at International Paralympic Committee VISTA2013 Scientific Conference, Bonn, 2013, Equipment & Technology in Paralympic Sports.
Open this publication in new window or tab >>Lower Leg Prosthesis for Cross-Country Skiing Classical Technique
2013 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-28019 (URN)
Conference
International Paralympic Committee VISTA2013 Scientific Conference, Bonn, 2013, Equipment & Technology in Paralympic Sports
Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2016-08-11Bibliographically approved
Bäckström, M., Tinnsten, M., Koptyug, A., Rännar, L.-E., Carlsson, P., Danvind, J. & Wiklund, H. (2013). Sports Technology Education at Mid Sweden University. In: 6TH ASIA-PACIFIC CONGRESS ON SPORTS TECHNOLOGY (APCST): . Paper presented at 6th Asia-Pacific Conference on Sports Technology, APCST 2013; Hong Kong; Hong Kong; 18 September 2013 through 20 September 2013; Code 101817 (pp. 214-219). Elsevier, 60
Open this publication in new window or tab >>Sports Technology Education at Mid Sweden University
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2013 (English)In: 6TH ASIA-PACIFIC CONGRESS ON SPORTS TECHNOLOGY (APCST), Elsevier, 2013, Vol. 60, p. 214-219Conference paper, Published paper (Refereed)
Abstract [en]

In present paper we would like to share some experiences of building new education in Sports Technology at MidSweden University and the results of 10 years of successfully running it in Östersund. The Sports Technologyeducation at Mid Sweden University started at Campus Östersund in 2003 as a part of the curriculum of theEngineering Department. This specialization was initially at the three-year Bachelor level, and later it was extendedto an additional two-year Master level. Aiming at the quality of Sports Technology education, three keystones areunderlying its process, representing the solid knowledge base, capacity to be flexible in problem solving and the usean innovative approaches. The Department unites researches with a background in both natural sciences andengineering disciplines, having a wide experience of working with and within the industry, equally active in researchand teaching. The unique constellation of the profiles forming the Department include not only the SportsTech®group, being “the backbone”, but also the Ecology and Eco-technology, and Quality Technology groups bringing theexcellence and extra competence needed to assure the quality of the Sports Technology education. We were the firsthigher education institution in Sweden to give this kind of education program and now some other SwedishUniversities have followed us. Our success can be measured by a number of graduates taking good jobs in theindustry. We also enjoy a steady flow of new students coming from all parts of Sweden, and Sports Technologyeducation stays among the most desirable ones in the country.

Place, publisher, year, edition, pages
Elsevier, 2013
Series
Procedia Engineering, ISSN 1877-7058
Keywords
Sports technology; university education; engineering of sports; outdoor
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-20584 (URN)10.1016/j.proeng.2013.07.037 (DOI)000326266100035 ()2-s2.0-84891708353 (Scopus ID)
Conference
6th Asia-Pacific Conference on Sports Technology, APCST 2013; Hong Kong; Hong Kong; 18 September 2013 through 20 September 2013; Code 101817
Available from: 2013-12-10 Created: 2013-12-10 Last updated: 2014-11-03Bibliographically approved
Lund Ohlsson, M., Stöggl, T. & Danvind, J. (2012). Asymmetry case study during skiing in the diagonal stride using a lower leg prosthesis. In: : . Paper presented at 2nd International Congress on Science and Nordic Skiing, Vuokatti, Finland, May 28-31, 2012.
Open this publication in new window or tab >>Asymmetry case study during skiing in the diagonal stride using a lower leg prosthesis
2012 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-28020 (URN)
Conference
2nd International Congress on Science and Nordic Skiing, Vuokatti, Finland, May 28-31, 2012
Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2016-06-30Bibliographically approved
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