Gymnastik- och idrottshögskolan, GIH

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  • 1.
    Andersson, Helena A
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Krustrup, Peter
    Elite football on artificial turf versus natural grass: movement patterns, technical standards, and player impressions.2008In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 26, no 2, p. 113-22Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.

  • 2.
    Andersson, Mitchell J
    et al.
    Malmö Addiction Center, Region Skåne, Clinical Sports and Mental Health Unit, Malmö, Sweden.; Faculty of Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden..
    Kenttä, Göran
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Swedish Sports Confederation, Stockholm, Sweden; School of Human Kinetics, University of Ottawa, Ottawa, Canada.
    Moesch, Karin
    Swedish Sports Confederation, Stockholm, Sweden.; Department of Sports Science, Malmö University, Malmö, Sweden.
    Borg, Elisabet
    Faculty of Social Sciences, Department of Psychology - Perception and Psychophysics, Stockholm University, Stockholm, Sweden..
    Claesdotter-Knutsson, Emma
    Faculty of Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden..
    Håkansson, Anders
    Malmö Addiction Center, Region Skåne, Clinical Sports and Mental Health Unit, Malmö, Sweden.; Faculty of Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden..
    Symptoms of depression and anxiety among elite high school student-athletes in Sweden during the COVID-19 pandemic: A repeated cross-sectional study.2023In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 41, no 9, p. 874-883Article in journal (Refereed)
    Abstract [en]

    The COVID-19 pandemic precipitated numerous changes in daily life, including the cancellation and restriction of sports globally. Because sports participation contributes positively to the development of student-athletes, restricting these activities may have led to long-term mental health changes in this population. Using a repeated cross-sectional study design, we measured rates of depression using the Patient Health Questionnaire-2 and anxiety using the Generalized Anxiety Disorder-2 scale in student-athletes attending elite sport high schools in Sweden during the second wave of the pandemic (February 2021; n = 7021) and after all restrictions were lifted (February 2022; n = 6228). Depression among student-athletes decreased from 19.8% in 2021 to 17.8% in 2022 (p = .008, V = .026), while anxiety screening did not change significantly (17.4% to 18.4%, p > .05). Comparisons between classes across years revealed older students exhibited decreases in depressive symptoms, while younger cohorts experienced increases in symptoms of anxiety from 2021 to 2022. Logistic regressions revealed that being female, reporting poorer mental health due to COVID-19, and excessive worry over one's career in sports were significant predictors of both depression and anxiety screenings in 2022. Compared to times when sports participation was limited, the lifting of restrictions was associated with overall reduced levels of depression, but not anxiety.

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  • 3. Aujla, Imogen J
    et al.
    Nordin-Bates, Sanna M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Sport Psychology research group.
    Redding, Emma
    Multidisciplinary predictors of adherence to contemporary dance training: findings from the UK Centres for Advanced Training.2015In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 33, no 15, p. 1564-73Article in journal (Refereed)
    Abstract [en]

    Little is known about the predictors of adherence in a dance context. The aim of this study was to investigate adherence to a dance talent programme using a multidisciplinary set of variables representing psychological correlates of adherence, maturation and physical factors relating to dance talent. Psychological (passion, motivational climate perceptions, eating attitudes), physical competence (vertical jump height, handgrip strength, hamstring flexibility, external hip rotation, aerobic fitness), and maturation-related (age of menarche) variables were gathered from female students enrolled on a dance talent programme. Participation behaviour (adherence/dropout) was collected from the talent programme's records approximately two years later. Logistic regression analysis of 287 participants revealed that greater levels of harmonious passion predicted greater likelihood of adherence to the programme, and greater ego-involving motivational climate perceptions predicted less likelihood of adherence. Neither measures of physical competence nor maturation distinguished adhering from dropout participants. Overall, the results of this study indicate that psychological factors are more important than physical competence and maturation in the participation behaviour of young talented dancers.

  • 4.
    Cardinale, Daniele A.
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Hyperoxia for performance and training.2018In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, no 13, p. 1515-1522Article in journal (Refereed)
    Abstract [en]

    Recent technological developments have made it possible to use hyperoxia as an enhancement aid during training. Athletes wearing a mask can breathe a higher fraction of oxygen from a stationary or portable apparatus while exercising. A large body of evidence indicates that the oxygen transport capacity, lactate metabolism, power output and work tolerance (endurance) are improved when breathing hyperoxia. The physiological mechanisms underlying these performance improvements, although still not fully elucidated, are based on higher oxygen delivery and reduced central fatigue. Although much is known about the acute effects of hyperoxia, the effect of hyperoxic-supplemented endurance training on performance and the mechanisms beneath training adaptations are not very well understood, especially in well-trained endurance athletes. The few studies on the physiological effects of hyperoxia training have been conducted with conflicting results, discussed in this paper. Potential detrimental effects have not yet been shown experimentally and warrant further investigation.

  • 5.
    Enqvist, Jonas K
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Mattsson, C Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Johansson, Patrik H
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Brink-Elfegoun, Thibault
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Bakkman, Linda
    Swedish School of Sport and Health Sciences, GIH.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Energy turnover during 24 hours and 6 days of adventure racing.2010In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 28, no 9, p. 947-955Article in journal (Refereed)
    Abstract [en]

    Energy turnover was assessed in two conditions of mixed ultra-endurance exercise. In Study 1, energy expenditure and intake were measured in nine males in a laboratory over 24 h. In Study 2, energy expenditure was assessed in six males during an 800-km Adventure race (mean race time 152.5 h). Individual correlations between heart rate and oxygen uptake ([Vdot]O(2)) were established during pre-tests when kayaking, cycling, and running. During exercise, energy expenditure was estimated from continuous heart rate recordings. Heart rate and [Vdot]O(2) were measured regularly during fixed cycling work rates to correct energy expenditure for drift in oxygen pulse. Mean energy expenditure was 18,050 +/- 2,390 kcal (750 +/- 100 kcal . h(-1)) and 80,000 +/- 18,000 kcal (500 +/- 100 kcal . h(-1)) in Study 1 and Study 2 respectively, which is higher than previously reported. Energy intake in Study 1 was 8,450 +/- 1,160 kcal, resulting in an energy deficit of 9,590 +/- 770 kcal. Body mass decreased in Study 1 (-2.3 +/- 0.8 kg) but was unchanged in Study 2. Fat mass decreased in Study 2 (-2.3 +/- 1.5 kg). In Study 1, muscle glycogen content decreased by only 60%. Adventure racing requires a high energy expenditure, with large inter-individual variation. A large energy deficit is caused by inadequate energy intake, possibly due to suppressed appetite and gastrointestinal problems. The oxygen pulse, comparing start to 12 h of exercise and beyond, increased by 10% and 5% in Study 1 and Study 2 respectively. Hence, estimations of energy expenditure from heart rate recordings should be corrected according to this drift.

  • 6.
    Fliess Douer, Osnat
    et al.
    KU, Leuven, Belgium; Israel Paralympic Committee, Tel Aviv, Israel; The Academic College at Wingate Institute, Israel.
    Koseff, Davidah
    Israel Paralympic Committee, Tel Aviv, Israel..
    Tweedy, Sean
    University of Queensland, St Lucia, Australia.
    Molik, Bartosz
    Jozef Pilsudski University of Physical Education, Warsaw, Poland..
    Vanlandewijck, Yves
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. KU, Leuven, Belgium.
    Challenges and opportunities in wheelchair basketball classification - A Delphi study.2021In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 39, no Sup1, p. 7-18Article in journal (Refereed)
    Abstract [en]

    The International Paralympic Committee (IPC) mandates Paralympic Sports to develop evidence-based classification systems that allocate athletes into 'classes' according to the impact of their impairment on sport-specific performance. In wheelchair-basketball, a panel of classifiers assesses athlete's performance through observation. One key barrier to evidence-based classification is the absence of defined eligible impairments, including clear guidelines on how to assess them and their impact on wheelchair basketball performance. This study aims to reach expert consensus on issues specific to wheelchair basketball that can benefit from evidence-based classification. It offers recommendations for refining the classification manual, thus improving adherence to the IPC classification code. A three-round Delphi study was conducted with 29 experts in wheelchair basketball. The experts agreed with the new definition for the aim of wheelchair basketball classification, which is in line with the IPC code. Cases identified as having the highest risk for disagreement between classifiers included classifying players with upper limb deficiency or with impaired coordination. The panel failed to agree on changing the classification procedures and on defining the eligible impairment list. This study identifies issues specific to wheelchair basketball classification to be addressed in future research. Additional discussions need to take place to promote further resolution.

  • 7.
    Ford, Paul R
    et al.
    University of Brighton, UK.
    Hodges, Nicola J
    University of British Columbia, Vancouver, Canada.
    Broadbent, David
    Brunel University, London, UK.
    O'Connor, Donna
    University of Sydney, Sydney, Australia..
    Scott, Dawn
    The Football Association, Burton upon Trent, UK.
    Datson, Naomi
    University of Chichester, UK.
    Andersson, Helena A
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Williams, A Mark
    University of Utah, UT, USA..
    The developmental and professional activities of female international soccer players from five high-performing nations.2020In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 38, no 11-12, p. 1432-1440Article in journal (Refereed)
    Abstract [en]

    We study the developmental and professional activities engaged in by 86 female adult soccer players from the senior national teams of Australia, Canada, England, Sweden, and the United States of America. Players completed the Participation History Questionnaire (PHQ) to elicit the amount and type of activities engaged in across their developmental and professional years, including milestones, soccer-specific activity and engagement in other sport activity. Greater specialisation than diversification characterised their childhood developmental activities, including all players starting in soccer in childhood and accumulating more hours in soccer activity than other sports during this period. However, interindividual variation further characterised these childhood activities, with a proportion of players diversifying into other sports and/or soccer play to a greater or lesser degree during childhood when compared to the other players. The amount of coach-led soccer practice increased for all players across their development culminating in an average of 15-16 h/wk across a 40-week season in early adulthood. In contrast, the amount of engagement in other sports and soccer peer-led play varied between players but generally decreased across adolescence to negligible amounts in late adolescence. Findings are commensurate with the deliberate practice framework and early engagement.

  • 8.
    Fröberg, Andreas
    et al.
    Department of Food and Nutrition and Sport Science, University of Gothenburg, Sweden.
    Lindroos, Anna-Karin
    Department of Risk Benefit Assessment, Swedish Food Agency, Uppsala, Sweden; Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Sweden.
    Moraeus, Lotta
    Department of Risk Benefit Assessment, Swedish Food Agency, Uppsala, Sweden; .
    Patterson, Emma
    Department of Risk Benefit Assessment, Swedish Food Agency, Uppsala, Sweden; Department of Global Public Health, Karolinska Institutet, Stockholm, Sweden..
    Warensjö Lemming, Eva
    Department of Risk Benefit Assessment, Swedish Food Agency, Uppsala, Sweden; .
    Nyberg, Gisela
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Global Public Health, Karolinska Institutet, Stockholm, Sweden..
    Leisure-time organised physical activity and dietary intake among Swedish adolescents.2022In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 40, no 11, p. 1198-1205Article in journal (Refereed)
    Abstract [en]

    This study aimed to investigate associations between participation in leisure-time organised physical activity (LTOPA) and dietary intake in a large representative sample of Swedish adolescents participating in the national dietary survey Riksmaten Adolescents 2016-2017. A sample of 2807 participants aged 11-12, 14-15 and 17-18 years were included. Information about LTOPA and dietary intake were collected through questionnaires and two 24-hour recalls on the web (RiksmatenFlex). For dietary intake, overall healthy eating index, intake of fruit, vegetables, candy, sugar-sweetened beverages, and the proportion of added sugar to total energy intake were analysed. Significance-testing for associations was performed with analysis of covariance. LTOPA was associated with lower sugar-sweetened beverages intake among adolescent boys (p < 0.001, ηp2 = 0.012) and girls (p = 0.007, ηp2 = 0.005), higher fruit intake among boys (p = 0.043, ηp2 = 0.003), and lower vegetable intake among girls (p < 0.001, ηp2 = 0.009). However, LTOPA was unrelated to the overall healthy eating index, candy intake, and the proportion of added sugar to total energy intake (p > 0.05). LTOPA was only associated with some healthy eating behaviours, and there is much room for improvement in the diets of Swedish adolescents.

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  • 9.
    Gray, Stuart R
    et al.
    Strathclyde inst of pharmacy and biomedical sciences, university of strathclyde, Glasgow UK.
    Söderlund, Karin
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Ferguson, Richard A
    ATP and phosphocreatine utilization in single human muscle fibres during the development of maximal power output at elevated muscle temperatures.2008In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 26, no 7, p. 701-7Article in journal (Refereed)
    Abstract [en]

    In this study, we examined the effect of muscle temperature (Tm) on adenosine triphosphate (ATP) and phosphocreatine utilization in single muscle fibres during the development of maximal power output in humans. Six male participants performed a 6-s maximal sprint on a friction-braked cycle ergometer under both normal (Tm = 34.3 degrees C, s = 0.6) and elevated (T(m) = 37.3 degrees C, s = 0.2) muscle temperature conditions. During the elevated condition, muscle temperature of the legs was raised, passively, by hot water immersion followed by wrapping in electrically heated blankets. Muscle biopsies were taken from the vastus lateralis before and immediately after exercise. Freeze-dried single fibres were dissected, characterized according to myosin heavy chain composition, and analysed for ATP and phosphocreatine content. Single fibres were classified as: type I, IIA, IIAX25 (1 - 25% IIX isoform), IIAX50 (26 - 50% IIX), IIAX75 (51 - 75% IIX), or IIAX100 (76 - 100% IIX). Maximal power output and pedal rate were both greater (P < 0.05) during the elevated condition by 258 W (s = 110) and 22 rev . min(-1) (s = 6), respectively. In both conditions, phosphocreatine content decreased significantly in all fibre types, with a greater decrease during the elevated condition in type IIA fibres (P < 0.01). Adenosine triphosphate content was also reduced to a greater (P < 0.01) extent in type IIA fibres during the elevated condition. The results of the present study indicate that after passive elevation of muscle temperature, there was a greater decrease in ATP and phosphocreatine content in type IIA fibres than in the normal trial, which contributed to the higher maximal power output.

  • 10.
    Hellström, John
    et al.
    Örebro universitet.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Isberg, Leif
    Örebro universitet.
    Drive for dough. PGA Tour golfers' tee shot functional accuracy, distance and hole score.2014In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 32, no 5, p. 462-9Article in journal (Refereed)
    Abstract [en]

    A player's ability to score low is critical to the tournament outcome in golf. The relationships of round scores to fairways hit in regulation or striking distance on two holes per round have been investigated before with some disagreement. The purpose is therefore to examine the relationships of par-4 and par-5 hole scores to tee shot functional accuracy and distance, measured as lie of the ball and penalty, and striking distance or distance to the pin for the second shot. Such information is possible to collect without interviewing players. The best US Professional Golfers' Association Tour players' statistics during a season are used, provided by the Professional Golfers' Association Tour and ShotLink. Distance was measured with laser equipment. The results include significant (P < 0.05) correlations between score and striking distance or distance to pin, when hitting rough but not fairway on par-4s and when hitting fairway and rough on par-5s. It is therefore relevant, for performance, to consider the type of fairway miss as well as the striking distance in relation to the par and length of the hole. The findings can be considered when making gap and needs profiles, and when making tactical decisions for tee shots on different types of holes.

  • 11. Holmberg, Hans-Christer
    et al.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Reliability and validity of a new double poling ergometer for cross-country skiers.2008In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 26, no 2, p. 171-9Article in journal (Refereed)
    Abstract [en]

    Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50-70% higher than that at the flywheel. There was a high test-retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W x kg(-1)) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.

  • 12. Holmberg, Hans-Christer
    et al.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Reliabilty and validity of new double poling ergometer for cross-country skiers2008In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 26, no 2, p. 171-179Article in journal (Refereed)
    Abstract [en]

    Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50 – 70% higher than that at the flywheel. There was a high test – retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W · kg−1) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.

  • 13.
    Jacques, Tiago Canal
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Bini, Rodrigo
    La Trobe Rural Health School , Bendigo, Australia.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institute, Sweden.
    Running after cycling induces inter-limb differences in muscle activation but not in kinetics or kinematics.2021In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 39, no 2, p. 154-160Article in journal (Refereed)
    Abstract [en]

    Overuse injuries are a common problem to triathletes' population. Overuse injuries may arise from inter-limb biomechanical differences during running, but the literature lacks information regarding inter-limb differences in triathletes. In this study inter-limb differences were investigated in injury-free triathletes during the running portion of a simulated cycle-run transition. Thirteen triathletes performed a 5 km run preceded by a 20 min cycling trial at 70% of maximal power output. During the Start, Mid and End stages of running, kinetic, kinematic and muscle activation variables were compared between the preferred and non-preferred limbs across the stance phase. A statistical parametric mapping analysis showed no differences between limbs when considering kinetic and kinematic variables (p > 0.05, ES<0.60). A lower soleus activation was observed in the preferred limb (p < 0.05, ES>0.60) from 53.40-75.9% of the stance phase at the End stage of running. In conclusion, inter-limb differences in kinetic or kinematic variables may not represent a risk for overloading in triathletes. However, inter-limb differences in triceps surae activation during running after cycling may represent one potential factor leading to overuse injuries in triathletes and should be further investigated.

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  • 14.
    Kalen, Anton
    et al.
    Univ Vigo, Fac Educ & Sport Sci, Pontevedra, Spain..
    Lundkvist, Erik
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ivarsson, Andreas
    Halmstad Univ, Sweden..
    Rey, Ezequiel
    Univ Vigo, Fac Educ & Sport Sci, Pontevedra, Spain..
    Perez-Ferreiros, Alexandra
    Univ Vigo, Fac Educ & Sport Sci, Pontevedra, Spain.; Univ Clin Hosp Santiago, RG Pediat Nutr IDIS CHUS, CiberObn Unit Pediat Nutr & Metab, Santiago De Compostela, Spain..
    The influence of initial selection age, relative age effect and country long-term performance on the re-selection process in European basketball youth national teams2021In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 39, no 4, p. 388-394Article in journal (Refereed)
    Abstract [en]

    The aims of the study were to: (a) analyse the re-selection patterns in European youth basketball national teams, and (b) investigate how the chance of re-selection is influenced by the initial selection age and relative age of the players, as well as the long-term performance of the country at the youth level. The sample consisted of 8362 basketball players (5038 men, 3324 women) born 1988-1997 who have participated in at least one U16, U18 or U20 European youth basketball championship between 2004 and 2017. The results from the survival analysis showed that around 75% of male and 80% of female players participating in a championship were re-selected the following year. Also, initial selection age, relative age effect, and the country long-term performance influenced the re-selection rates, with relationships being different between men and women. To conclude, the results of the present study show that the re-selection process by which players progress in European youth national basketball teams is complex and influenced by several different factors.

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  • 15. Karlsen, Jon
    et al.
    Smith, Gerald
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The stroke has a minor influence on direction consistencyin golf putting among elite players2008In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 3, p. 243-250Article in journal (Refereed)
    Abstract [en]

    In the golf instructional literature, the putting stroke is typically given higher priority than green reading and aiming. The main purpose of this study was to assess the importance of the putting stroke for direction consistency in golf putting. Kinematic stroke parameters were recorded from 71 elite golf players (mean handicap = 1.8, s = 4.2) on 1301 putts from about 4 m. Of the different factors deciding stroke direction consistency, face angle was found to be the most important (80%), followed by putter path (17%) and impact point (3%). This suggests that improvements in consistency of putter path and impact point will have very little effect on overall putting direction consistency and should not be prioritized in the training of elite players. In addition, mean stroke direction variability for an elite player (European Tour) was found to be 0.39°, which is good enough to hole about 95% of all 4-m putts. In practice, however, top professionals in tournaments only hole about 17% of 4-m putts. We conclude that the putting stroke of elite golfers has a relatively minor influence on direction consistency.

  • 16. Karlsen, Jon
    et al.
    Smith, Gerald
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The stroke has only a minor influence on direction consistency in golf putting among elite players.2008In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 26, no 3, p. 243-50Article in journal (Refereed)
    Abstract [en]

    In the golf instructional literature, the putting stroke is typically given higher priority than green reading and aiming. The main purpose of this study was to assess the importance of the putting stroke for direction consistency in golf putting. Kinematic stroke parameters were recorded from 71 elite golf players (mean handicap = 1.8, s = 4.2) on 1301 putts from about 4 m. Of the different factors deciding stroke direction consistency, face angle was found to be the most important (80%), followed by putter path (17%) and impact point (3%). This suggests that improvements in consistency of putter path and impact point will have very little effect on overall putting direction consistency and should not be prioritized in the training of elite players. In addition, mean stroke direction variability for an elite player (European Tour) was found to be 0.39 degrees, which is good enough to hole about 95% of all 4-m putts. In practice, however, top professionals in tournaments only hole about 17% of 4-m putts. We conclude that the putting stroke of elite golfers has a relatively minor influence on direction consistency.

  • 17. Lees, A
    et al.
    Nolan, Lee
    Liverpool John Moores University.
    The biomechanics of soccer: a review.1998In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 16, no 3, p. 211-34Article in journal (Refereed)
    Abstract [en]

    This review considers the biomechanical factors that are relevant to success in the game of soccer. Three broad areas are covered: (1) the technical performance of soccer skills; (2) the equipment used in playing the game; and (3) the causative mechanisms of specific soccer injuries. Kicking is the most widely studied soccer skill. Although there are many types of kick, the variant most widely reported in the literature is the maximum velocity instep kick of a stationary ball. In contrast, several other skills, such as throwing-in and goalkeeping, have received little attention; some, for example passing and trapping the ball, tackling, falling behaviour, jumping, running, sprinting, starting, stopping and changing direction, have not been the subject of any detailed biomechanical investigation. The items of equipment reviewed are boots, the ball, artificial and natural turf surfaces and shin guards. Little of the research conducted by equipment manufacturers is in the public domain; this part of the review therefore concentrates on the mechanical responses of equipment, player-equipment interaction, and the effects of equipment on player performance and protection. Although the equipment has mechanical characteristics that can be reasonably well quantified, the player-equipment interaction is more difficult to establish; this makes its efficacy for performance or protection difficult to predict. Some soccer injuries may be attributable to the equipment used. The soccer boot has a poor protective capability, but careful design can have a minor influence on reducing the severity of ankle inversion injuries. Performance requirements limit the scope for reducing these injuries; alternative methods for providing ankle stability are necessary. Artificial surfaces result in injury profiles different from those on natural turf pitches. There is a tendency for fewer serious injuries, but more minor injuries, on artificial turf than on natural turf pitches. Players adapt to surface types over a period of several games. Therefore, changing from one surface to another is a major aetiological factor in surface-related injuries. Heading the ball could lead to long-term brain damage. Simulation studies suggest the importance of ball mass, ball speed and player mass in affecting the severity of impact. Careful instruction and skill development, together with the correct equipment, is necessary for young players. Most applications of biomechanical techniques to soccer have been descriptive experimental studies. Biomechanical modelling techniques have helped in the understanding of the underlying mechanisms of performance, although their use has been limited. It is concluded that there are still many features of the game of soccer that are amenable to biomechanical treatment, and many opportunities for biomechanists to make a contribution to the science of soccer.

  • 18. Li, Xiao
    et al.
    Wang, Shi-Jun
    Tan, Shing Cheng
    Chew, Pey Ling
    Liu, Lihong
    Wang, Li
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Wen, Li
    Ma, Lihong
    The A55T and K153R polymorphisms of MSTN gene are associated with the strength training-induced muscle hypertrophy among Han Chinese men.2014In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 32, no 9, p. 883-91Article in journal (Refereed)
    Abstract [en]

    Myostatin, encoded by the MSTN gene, is a strong regulator of skeletal muscle growth. The present study aimed to investigate whether the A55T and K153R polymorphisms of MSTN were associated with the strength training-induced muscle hypertrophy among Han Chinese men. A total of 94 healthy, untrained men were recruited for an 8-week strength training programme. The thicknesses of biceps and quadriceps, along with anthropometric measurements of the participants, were assessed before and after the programme. The MSTN polymorphisms were subsequently genotyped employing polymerase chain reaction-restriction fragment length polymorphism technique and confirmed by DNA sequencing. One-way analysis of variance was used to compare the pre- and post-training measurements between carriers of different polymorphic genotypes. Our results indicated that individuals with AT + TT genotype of the A55T polymorphism showed a significant increase in the thickness of biceps (0.292 ± 0.210 cm, P = 0.03), but not quadriceps (0.254 ± 0.198 cm, P = 0.07), compared to carriers of AA genotype. For the K153R polymorphism, the increases in the thicknesses of both biceps (0.300 ± 0.131 cm) and quadriceps (0.421 ± 0.281 cm) were significantly higher among individuals with KR than those with KK genotypes (P < 0.01 for both muscles). The results obtained therefore suggested a possible association between the two polymorphisms and the strength training-induced muscle hypertrophy among men of Han Chinese ethnicity.

  • 19.
    Lundqvist, Carolina
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Sport Psychology research group.
    Hassmén, Peter
    Competitive State Anxiety Inventory-2: Evaluating the Swedish version by confirmatory factor analyses2005In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 23, no 7, p. 727-736Article in journal (Refereed)
    Abstract [en]

    The Competitive State Anxiety Inventory-2 (CSAI-2) is one of the most frequently used instruments when assessing competitive state anxiety in sport psychology research. However, doubts have been expressed about the factorial validity of both the English and the Greek versions of the scale. Hence, a revised version of the inventory (CSAI-2R) has recently been suggested to be more psychometrically sound (Cox et al., 2003). In the present study, the aim was to evaluate the psychometric properties of the Swedish version of the CSAI-2 using confirmatory factor analyses. A total of 969 athletes (571 men and 398 women) competing in 26 different sports completed the Swedish version of the CSAI-2. Three different factor structures were evaluated: the original three-factor model (with cognitive anxiety, somatic anxiety and self-confidence), a two-factor model in which self-confidence was excluded, and a three-factor model containing 17 items (CSAI-2R). The results revealed that only the 17-item model displayed an acceptable fit to the data. Although some doubts remain about the amount of variance that can be attributed to error variance in the subscales, the results suggest that it is better to use the CSAI-2R rather than the original CSAI-2.

  • 20.
    Mandroukas, Athanasios
    et al.
    Charles University , Prague, Czech Republic.
    Metaxas, Thomas I
    Aristotle University of Thessaloniki , Thessaloniki, Greece.
    Papadopoulou, Zacharoula
    Aristotle University of Thessaloniki , Thessaloniki, Greece.
    Heller, Jan
    Charles University , Prague, Czech Republic.
    Margaritelis, Nikos V
    Aristotle University of Thessaloniki , Thessaloniki, Greece.
    Christoulas, Kosmas
    Aristotle University of Thessaloniki , Thessaloniki, Greece.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Vrabas, Ioannis S
    Aristotle University of Thessaloniki , Thessaloniki, Greece.
    Myosin heavy chain isoform composition in the deltoid and vastus lateralis muscles of elite handball players.2020In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 38, no 20, p. 2390-2395Article in journal (Refereed)
    Abstract [en]

    The purpose of the present study was to compare the myosin heavy chain (MHC) isoform composition of the deltoid and vastus lateralis muscles of the dominant and non-dominant limbs in handball players. Eleven male Greek elite handball players (age 22.6 ± 1.9 yrs, training experience 10.6 ± 2.1 yrs, height 184.1 ± 4.1 cm, and weight 81.0 ± 12.5 kg) participated in the study. Four muscle biopsies were obtained from the dominant and non-dominant deltoid and vastus lateralis muscles during the in-season period. The MHC composition was determined using SDS-PAGE. No significant difference was found between the dominant and non-dominant muscles; Deltoid muscle: MHC I [(95%CI = -1.22, 0.33), P = 0.228], MHC ΙΙa [(95%CI = -0.32, 1.59), P = 0.168] and MHC IIx [(95%CI = -1.49, 1.10), P = 0.749]; Vastus lateralis muscle: MHC I [(95%CI = -0.38, 0.63), P = 0.586], MHC ΙΙa [(95%CI = -0.50, 0.65), P = 0.783] and MHC IIx [(95%CI = -1.08, 0.42), P = 0.355]. The findings of the present study indicate that the greater use of the dominant limbs for throwing actions and body movements in handball do not lead to altered MHC isoform composition compared to the non-dominant limbs.

  • 21.
    Mann, David L
    et al.
    Vrije Universiteit Amsterdam, The Netherlands.
    Tweedy, Sean M
    University of Queensland, Brisbane, Australia..
    Jackson, Robin C
    Loughborough University, Loughborough, UK.
    Vanlandewijck, Yves
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. KU Leuven, Leuven, Belgium.
    Classifying the evidence for evidence-based classification in Paralympic sport.2021In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 39, no sup1, p. 1-6Article in journal (Other academic)
  • 22. Mitchell, Lachlan J G
    et al.
    Morris, Kirstin S
    Bolam, Kate
    Karolinska Institute, Stockholm, Sweden.
    Pritchard-Peschek, Kellie R
    Skinner, Tina L
    Shephard, Megan E
    The non-linear relationship between sum of 7 skinfolds and fat and lean mass in elite swimmers.2020In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 38, no 20, p. 2307-2313Article in journal (Refereed)
    Abstract [en]

    Body composition can substantially impact elite swimming performance. In practice, changes in fat and lean mass of elite swimmers are estimated using body mass, sum of seven skinfolds (∑7) and lean mass index (LMI). However, LMI may be insufficiently accurate to detect small changes in body composition which could meaningfully impact swimming performance. This study developed equations which estimate dual-energy x-ray absorptiometry (DXA)-derived lean and fat mass using body mass and ∑7 data. Elite Australian swimmers (n = 44; 18 male, 26 female) completed a DXA scan and standardised body mass and ∑7 measurements. Equations to estimate DXA-derived lean and fat mass based on body mass, ∑7 and sex were developed. The relationships between ∑7, body mass and DXA-derived lean and fat mass were non-linear. Fat mass (Adjusted R2 = 0.91; standard error = 1.0 kg) and lean mass (Adjusted R2 = 0.99; standard error = 1.0 kg) equations were considered sufficiently accurate. Lean mass estimates outperformed the LMI in identifying the correct direction of change in lean mass (82% correct; LMI 71%). Using the accurate estimations produced by these equations will enhance the prescription and evaluation of programmes to optimise the body composition and subsequent performance in swimmers.

  • 23.
    Muchaxo, Rafael
    et al.
    Vrije Univ Amsterdam, Fac Behav & Human Movement Sci, Amsterdam, Netherlands.;Amsterdam Rehabil Res Ctr, Amsterdam, Netherlands..
    De Groot, Sonja
    Vrije Univ Amsterdam, Fac Behav & Human Movement Sci, Amsterdam, Netherlands.;Amsterdam Rehabil Res Ctr, Amsterdam, Netherlands.;Amsterdam Inst Sport Sci, Ctr Adapted Sports Amsterdam, Amsterdam, Netherlands..
    Kouwijzer, Ingrid
    Amsterdam Rehabil Res Ctr, Amsterdam, Netherlands.;Heliomare Rehabil Ctr, Res & Dev, Wijk Aan Zee, Netherlands.;Univ Groningen, Univ Med Ctr Groningen, Ctr Human Movement Sci, Groningen, Netherlands..
    Van Der Woude, Lucas
    Univ Groningen, Univ Med Ctr Groningen, Ctr Human Movement Sci, Groningen, Netherlands.;Univ Groningen, Univ Med Ctr Groningen, Ctr Rehabil, Groningen, Netherlands.;Loughborough Univ, Sch Sports Exercise & Hlth, Peter Harrison Ctr Disabil Sport, Loughborough, Leics, England..
    Janssen, Thomas
    Vrije Univ Amsterdam, Fac Behav & Human Movement Sci, Amsterdam, Netherlands.;Amsterdam Rehabil Res Ctr, Amsterdam, Netherlands.;Amsterdam Inst Sport Sci, Ctr Adapted Sports Amsterdam, Amsterdam, Netherlands..
    Nooijen, Carla F J
    Swedish School of Sport and Health Sciences, GIH.
    A Role for Trunk Function in Elite Recumbent Handcycling Performance?2021In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 39, no 20, p. 2312-2321Article in journal (Refereed)
    Abstract [en]

    Handcycling classification considers trunk function, but there is limited scientific evidence of trunk involvement in recumbent performance. This study investigated the association between trunk function and recumbent handcycling performance of athletes without upper-limb impairments (H3-H4 sport classes). The study was divided into two parts. First, 528 time-trial results from 81 handcyclists with spinal cord injury (SCI) were obtained between 2014 and 2020. Average time-trial velocity was used as performance measure and SCI level as trunk function determinant. Multilevel regression analysis was performed to analyse differences in performance among SCI groups while correcting for lesion completeness, sex, and age. Second, in 26 handcyclists, standardised trunk flexion strength was measured with a handheld dynamometer. Peak and mean power-output from a sprint test and time-trial average velocity were used as performance measures. Spearman correlations were conducted to investigate the association between trunk strength and performance. Results showed that the different SCI groups did not exhibit significant differences in performance. Furthermore, trunk flexion strength and performance exhibited non-significant weak to moderate correlations (for time-trial speed: rs = 0.36; p = 0.07). Results of both analyses suggest that trunk flexion strength does not seem to significantly impact recumbent handcycling performance in athletes without upper-limb impairments.

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  • 24.
    Nilsson, Johnny
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Csergö, Sandor
    Gullstrand, Lennart
    Tveit, Per
    Refsnes, Per Egil
    Work-time profile, blood lactate concentration and rating of perceived exertion in the 1998 Greco-Roman Wrestling World Championship.2002In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 20, no 11, p. 939-45Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to examine work-time profiles, blood lactate concentrations and perceived exertion among Greco-Roman wrestlers in the 1998 World Championship. Forty-two senior wrestlers from nine nations were studied in 94 matches. Each match was recorded with a video camera (Panasonic AG 455, film rate: 25 Hz) and analysed for duration of work (wrestling) and rest (interrupt) periods. Blood lactate concentration was determined with an electrochemical device (Analox P-LM5) and a rating of perceived exertion scale (Borg) was used to estimate general exertion and exertion in the extremity and trunk muscles. The mean duration of the matches was 427 s (range 324-535 s), with mean durations of work and rest of 317 and 110 s, respectively. The mean periods of work and rest were 37.2 and 13.8 s, respectively. Mean blood lactate concentration was 14.8 mmol x 1(-1) (range 6.9-20.6). The difference in mean blood lactate concentration between the first- and final-round matches was not significant (P > 0.05). Blood lactate concentration was significantly higher (P < 0.04) in matches of long duration than in those of short duration. The mean general rating of perceived exertion for all matches was 13.8 according to the scale used. Most of the wrestlers (53.3%) perceived exertion to be highest in the flexors of the forearm, followed by the deltoids (17.4%) and the biceps brachii muscles (12.0%). In addition to a relatively high rating of perceived exertion in the arm muscles, this indicates a high specific load on the flexor muscles of the forearm.

  • 25.
    Nilsson, Johnny
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Haugen, Per
    Knee angular displacement and extensor muscle activity in telemark skiing and in ski-specific strength exercises.2004In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 22, no 4, p. 357-64Article in journal (Refereed)
    Abstract [en]

    Much of the training of competitive telemark skiers is performed as dry-land exercises. The specificity of these exercises is important for optimizing the training effect. Our aim here was to study the activation of the knee extensor musculature and knee angular displacement during competitive telemark skiing and during dry-land strength training exercises to determine the specificity of the latter. Specificity was analysed with respect to angular amplitude, angular velocity, muscle action and electromyographic (EMG) activity. Five male telemark skiers of national and international standard volunteered to participate in the study, which consisted of two parts: (1) skiing a telemark ski course and (2) specific dry-land strength training exercises for telemark skiing (telemark jumps and barbell squats). The angular displacement of the right knee joint was recorded with an electrogoniometer. A tape pressure sensor was used to measure pressure between the sole of the foot and the bottom of the right ski boot. Electromyographic activity in the right vastus lateralis was recorded with surface electrodes. The EMG activity recorded during maximum countermovement jumps was used to normalize the EMG activity during telemark skiing, telemark jumps and barbell squats. The results showed that knee angular displacement during telemark skiing and dry-land telemark jumps had four distinct phases: a flexion (F1) and extension (E1) phase during the thrust phase of the outside ski/leg in the turn/jump and a flexion (F2) and extension (E2) phase when the leg was on the inside of the turn/jump. The vastus lateralis muscle was activated during F1 and E1 in the thrust phase during telemark skiing and telemark jumps. The overall net knee angular amplitude was significantly greater (P < 0.05) for telemark jumps than for telemark skiing. Barbell squats showed a knee angular amplitude significantly greater than that in telemark skiing (P < 0.05). The mean knee angular velocity of the F1 and E1 phases during telemark skiing was about 0.47 rad x s(-1); during barbell squats, it was about 1.22 rad x s(-1). The angular velocity during telemark jumps was 2.34 and 1.59 rad x s(-1) in the F1 and E1 phase, respectively. The normalized activation level of the EMG bursts during telemark skiing, telemark jumps and barbell squats was 70-80%. In conclusion, the muscle action and level of activation in the vastus lateralis during the F1 and E1 phases were similar during telemark skiing and dry-land exercises. However, the dry-land exercises showed a larger knee extension and flexion amplitude and angular velocity compared with telemark skiing. It appears that an adjustment of knee angular velocity during barbell squats and an adjustment of knee angle amplitude during both telemark jumps and barbell squats will improve specificity during training.

  • 26.
    Nilsson, Johnny
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Karlsen, Jon
    A new device for evaluating distance and directional performance of golf putters.2006In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 24, no 2, p. 143-7Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to construct and evaluate the reliability of an apparatus for testing golf putters with respect to distance and direction deviation at different impact points on the clubface. An apparatus was constructed based on the pendulum principle that allowed putter golf clubs to swing at different speeds. The mean speed of the club head before ball impact, and of the ball after impact, was calculated from time measurements with photocells. A pin profile rig was used to determine the directional deviation of the golf ball. Three different putters were used in the study, two that are commercially available (toe-heel weighted and mallet types) and one specially made (wing-type) putter. The points of impact were the sweet spot (as indicated by the manufacturer's aim line), and 1, 2 and 3 cm to the left and right of the sweet spot. Calculation of club head speed before impact, and of ball speed after impact (proportional to distance), showed errors < or = 0.5% of interval duration. The variability in ball impacts was tested by measuring time and direction deviations during 50 impacts on the same ball. The mean duration (+/- s) after ball impact in the test interval (1.16 m long) was 206 (0.8) ms and the standard deviation in the perpendicular spreading of the balls in relation to the direction of the test interval was 0.005 m. A test-retest of one putter on two consecutive days after remounting of the putter on the test apparatus showed less than 1% difference in distance deviation. We conclude that the test apparatus enables a precise recording of distance and direction deviation in golf putters as well as comparisons between different putters. The apparatus and set-up can be used in the laboratory as well as outdoors on the putting green.

  • 27.
    Nolan, Lee
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lees, Adrian
    The influence of lower limb amputation level on the approach in the amputee long jump.2007In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 25, no 4, p. 393-401Article in journal (Refereed)
    Abstract [en]

    In this study, we investigated the adjustments to posture, kinematic and temporal characteristics of performance made by lower limb amputees during the last few strides in preparation for long jump take-off. Six male unilateral trans-femoral and seven male unilateral trans-tibial amputees competing in a World Championships final were filmed in the sagittal plane using a 100-Hz digital video camera positioned so that the last three strides to take-off were visible. After digitizing using a nine-segment model, a range of kinematic variables were computed to define technique characteristics. Both the trans-femoral and trans-tibial athletes appeared to achieve their reduction in centre of mass during the flight phase between strides, and did so mainly by extending the flight time by increasing stride length, achieved by a greater flexion of the hip joint of the touch-down leg. The trans-tibial athletes appeared to adopt a technique similar to that previously reported for able-bodied athletes. They lowered their centre of mass most on their second last stride (-1.6% of body height compared with -1.4% on the last stride) and used a flexed knee at take-off on the last stride, but they were less able to control their downward velocity at touch-down (-0.4 m x s(-1)). Both this and their restricted approach speed (8.9 m x s(-1) at touch-down), rather than technique limitations, influenced their jump performance. The trans-femoral athletes lowered their centre of mass most on the last stride (-2.3% of body height compared with -1.6% on the second last stride) and, as they were unable to flex their prosthetic knee sufficiently, achieved this by abducting their prosthetic leg during the support phase, which led to a large downward velocity at touch-down (-0.6 m x s(-1)). This, combined with their slower approach velocity (7.1 m x s(-1) at touch-down), restricted their performance.

  • 28. Reilly, Thomas
    et al.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    The use of recovery methods post-exercise.2005In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 23, no 6, p. 619-27Article in journal (Refereed)
    Abstract [en]

    Competitive soccer engages many of the body's systems to a major extent. The musculoskeletal, nervous, immune and metabolic systems are stressed to a point where recovery strategies post-exercise become influential in preparing for the next match. Intense activity at a 7-day training camp causes participants to experience lowered concentrations of non-killer cells and T-helper cells. Two consecutive games in 24 h produce disturbances in the testosterone-cortisol ratio. When competitive schedules are congested, the recovery process should be optimized for performance capabilities to be restored to normal as soon as possible. There is evidence that glycogen stores are reduced near to depletion at the end of a soccer game and that a diet high in carbohydrates can aid recovery. Water alone is not the best means of restoring body fluids, since carbohydrate-electrolyte drinks display better intestinal absorption and reduce urine output. Some relief from muscle soreness may be achieved by means of a warm-down. Deep-water running regimens can replace conventional physical training in the days after competition. Massage, cryotherapy and alternative therapies have not been shown to be consistently effective. It is concluded that optimizing recovery post-exercise depends on a combination of factors that incorporate a consideration of individual differences and lifestyle factors. The procedures to facilitate recovery processes should start immediately the game or training finishes. Match administrators and tournament planners should consider the stressful consequences for players in periods of congested fixtures and alleviate the physiological strain as far as possible by allowing 72 h between competitive games. This frequency of competition is unlikely to be sustainable in the long term.

  • 29.
    Rispal, Gauthier
    et al.
    Mid Sweden Univ, Swedish Winter Sports Res Ctr, Dept Hlth Sci, Östersund, Sweden.; Univ Aix Marseille, Fac Sport Sci, Marseille, France..
    Severin, Anna Cecilia
    Norwegian Univ Sci & Technol, Ctr Elite Sports Res, Dept Neuromed & Movement Sci, Trondheim, Norway..
    Baumgart, Julia Kathrin
    Norwegian Univ Sci & Technol, Ctr Elite Sports Res, Dept Neuromed & Movement Sci, Trondheim, Norway..
    Lund Ohlsson, Marie
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Mid Sweden Univ, Swedish Winter Sports Res Ctr, Dept Hlth Sci, Östersund, Sweden..
    Staunton, Craig A.
    Mid Sweden Univ, Swedish Winter Sports Res Ctr, Dept Hlth Sci, Ostersund, Sweden.; Swedish Winter Sports Res Ctr, Östersund, Sweden..
    Performance and micro-pacing strategies in sit para-biathlon2023In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 41, no 7, p. 646-653Article in journal (Refereed)
    Abstract [en]

    This study investigated micro-pacing strategies during sit para-biathlon. Six elite sit para-biathletes wore a positioning system device during the world-championships in three different competition formats (Sprint, Middle-distance, and Long-distance). Total Skiing Time (TST), penalty-time, shooting-time, and Total Race Time (TRT) were analysed. One-way analyses of variance were used to compare the relative contributions of TST, penalty-time, and shooting-time to TRT across the three race formats. Statistical parametric mapping (SPM) was used to determine the course positions (clusters) where instantaneous skiing speed was significantly associated with TST. The contribution of TST to TRT was lower for the Long-distance (80 & PLUSMN; 6%) compared to the Sprint (86 & PLUSMN; 5%) and Middle-distance (86 & PLUSMN; 3%) races, however this difference was not statistically significant (p > 0.05). The proportional contribution of penalty-time to TRT was significantly greater (p < 0.05) for the Long-distance (13 & PLUSMN; 6%) compared to the Sprint (5 & PLUSMN; 4%) and Middle-distance (4 & PLUSMN; 3%) races. Statistical parametric mapping (SPM) revealed specific clusters where instantaneous skiing speed was significantly associated with TST. For example, over all laps during the Long-distance race, the fastest athlete gained 6.5 s over the slowest athlete in the section with the steepest uphill. Overall, these findings can provide insights into pacing strategies and help para-biathlon coaches and athletes optimise training programmes to improve performance.

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  • 30. Rosenbloom, Christine A
    et al.
    Loucks, Anne B
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Special populations: the female player and the youth player.2006In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 24, no 7, p. 783-93Article in journal (Refereed)
    Abstract [en]

    Females and youth are frequently described as "special" populations in football literature, but together these two populations outnumber male players. What makes females "special" is that they tend to eat less when training and competing than their male counterparts, leading to lower intakes of energy, carbohydrate, and some nutrients. Youth football players are special in regard to energy and nutrient requirements to promote growth and development, as well as to fuel sport. There is limited research on the dietary habits of these two populations, but the available literature suggests that many female and youth players need to increase carbohydrate intake, increase fluid intake, and develop dietary habits to sustain the demands of training and competition.

  • 31.
    Rosén, Johanna S
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Goosey-Tolfrey, Victoria L
    Loughborough University, UK.
    Mason, Barry S
    Loughborough University, UK.
    Hutchinson, Michael J
    Loughborough University, UK.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Bjerkefors, Anna
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The impact of impairment on kinematic and kinetic variables in Va'a paddling: Towards a sport-specific evidence-based classification system for Para Va'a.2019In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 37, no 17, p. 1942-1950Article in journal (Refereed)
    Abstract [en]

    Para Va'a is a new Paralympic sport in which athletes with trunk and/or leg impairment compete over 200 m. The purpose of this study was to examine the impact of impairment on kinematic and kinetic variables during Va'a ergometer paddling. Ten able-bodied and 44 Para Va'a athletes with impairments affecting: trunk and legs (TL), legs bilaterally (BL) or leg unilaterally (UL) participated. Differences in stroke frequency, mean paddling force, and joint angles and correlation of the joint angles with paddling force were examined. Able-bodied demonstrated significantly greater paddling force as well as knee and ankle flexion ranges of movement (ROM) on the top hand paddling side compared to TL, BL and UL. Able-bodied, BL and UL demonstrated greater paddling force and trunk flexion compared to TL, and UL demonstrated larger bottom hand paddling side knee and ankle flexion ROM compared to BL. Significant positive correlations were observed for both male and female athletes between paddling force and all trunk flexion angles and ROM in the trunk and pelvis rotation and bottom hand paddling side hip, knee and ankle flexion. The results of this study are important for creating an evidence-based classification system for Para Va'a.

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  • 32.
    Sandamas, Paul
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Gutierrez-Farewik, Elena M
    KTH, Karolinska institutet.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    The effect of a reduced first step width on starting block and first stance power and impulses during an athletic sprint start.2019In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 37, no 9, p. 1046-1054Article in journal (Refereed)
    Abstract [en]

    This study investigated how manipulating first step width affects 3D external force production, centre of mass (CoM) motion and performance in athletic sprinting. Eight male and 2 female competitive sprinters (100m PB: 11.03 ± 0.36 s male and 11.6 ± 0.45 s female) performed 10 maximal effort block starts. External force and three-dimensional kinematics were recorded in both the block and first stance phases. Five trials were performed with the athletes performing their preferred technique (Skating) and five trials with the athletes running inside a 0.3 m lane (Narrow). By reducing step width from a mean of 0.31 ± 0.06 m (Skating) to 0.19 ± 0.03 m (Narrow), reductions were found between the two styles in medial block and medial 1st stance impulses, 1st stance anterior toe-off velocity and mediolateral motion of the CoM. No differences were found in block time, step length, stance time, average net resultant force vector, net anteroposterior impulse nor normalised external power. Step width correlated positively with medial impulse but not with braking nor net anteroposterior impulse. Despite less medially directed forces and less mediolateral motion of the CoM in the Narrow trials, no immediate improvement to performance was found by restricting step width.

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  • 33.
    Sandamas, Paul
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Gutierrez-Farewik, Elena M.
    KTH and Karolinska institutet, Sweden.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The relationships between pelvic range of motion, step width and performance during an athletic sprint start2020In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 38, no 19, p. 2200-2207Article in journal (Refereed)
    Abstract [en]

    The aims of this study were (a) to describe the kinematics underlying the phenomenon of the knee of the swing leg passing medially in front of the athlete during the single push (SP) phase of the block sprint start, and (b) to determine the relationships between block phase pelvis range of motion (RoM), 1st step width and block phase performance. Three-dimensional kinematic data (250 Hz) were collected from eleven competitive sprinters (100 m PB: 11.17 ± 0.41) performing maximal effort block starts. The joint angles of the rear hip with respect to the pelvis and the pelvis segment angles with respect to the laboratory coordinate system were calculated during the block start phase to the end of the 1st stance. A combination of pelvis list and rotation (not hip adduction) was coupled with the thigh of the swing leg moving medially during the SP phase. A very high positive correlation was found between pelvic list RoM and 1st step width (r = 0.799, p = 0.003). No other significant correlations were found. Attempting to reduce pelvic RoM or changing frontal and transverse plane hip joint angles to minimise medial thigh motion is unlikely to lead to an improvement to performance.

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  • 34. Spurway, N C
    et al.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Noakes, T D
    Wagner, P D
    What limits VO2max?: A symposium held at the BASES Conference, 6 September 20102012In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 30, no 6, p. 517-531Article in journal (Refereed)
    Abstract [en]

    Three modern views about the factors limiting oxygen uptake in healthy humans are set against the original (early 1920s) concept of A. V. Hill and colleagues. The majority view for most of the intervening time has been that cardiac output is the essential limiting function. Among recent research in support of this contention is that, in quadrupeds, pericardiectomy, which allows greater diastolic filling, elevates maximum oxygen uptake; however, the relevance to bipedal exercise can be questioned. In any case, algebraic analyses of model systems indicate that all identifiable stages on the oxygen transport pathway, from pulmonary diffusion to oxidative phosphorylation in skeletal muscle mitochondria, materially influence maximum uptake. Thus, if a high cardiac output is to be of benefit, all the other steps must function better too. Nevertheless, these two viewpoints concur that the limit to maximum oxygen uptake is somatic. In contrast, there are strong indications that at altitudes where oxygen availability is about half that at sea level, cerebral oxygenation is a limiting factor, and some recent experiments raise the possibility that it might be a substantial influence at sea level also. Clearly, consensus cannot yet be reached on the question posed in the title.

  • 35. Thelwell, Richard C
    et al.
    Wagstaff, Christopher R D
    Chapman, Michael T
    Kenttä, Göran
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Sport Psychology research group.
    Examining coaches' perceptions of how their stress influences the coach-athlete relationship.2017In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 35, no 19, p. 1928-1939Article in journal (Refereed)
    Abstract [en]

    This study extends recent coach stress research by evaluating how coaches perceive their stress experiences to affect athletes, and the broader coach-athlete relationship. A total of 12 coaches working across a range of team sports at the elite level took part in semi-structured interviews to investigate the 3 study aims: how they perceive athletes to detect signals of coach stress; how they perceive their stress experiences to affect athletes; and, how effective they perceive themselves to be when experiencing stress. Following content analysis, data suggested that coaches perceived athletes able to detect when they were experiencing stress typically via communication, behavioural, and stylistic cues. Although coaches perceived their stress to have some positive effects on athletes, the overwhelming effects were negative and affected "performance and development", "psychological and emotional", and "behavioural and interaction" factors. Coaches also perceived themselves to be less effective when stressed, and this was reflected in their perceptions of competence, self-awareness, and coaching quality. An impactful finding is that coaches are aware of how a range of stress responses are expressed by themselves, and to how they affect athletes, and their coaching quality. Altogether, findings support the emerging view that coach stress affects their own, and athlete performance.

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