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  • 1.
    Bjorklund, Glenn
    et al.
    Mid Sweden Univ, Dept Hlth Sci, Swedish Winter Sports Res Ctr, Ostersund, Sweden.;Swedish Sports Confederat, Stockholm, Sweden..
    Svarén, Mikael
    KTH, School of Engineering Sciences (SCI).
    Born, Dennis-Peter
    Swiss Fed Inst Sport, Dept Elite Sport, Magglingen, Switzerland..
    Stoeggl, Thomas
    Univ Salzburg, Dept Sport & Exercise Sci, Salzburg, Austria..
    Biomechanical Adaptations and Performance Indicators in Short Trail Running2019In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, article id 506Article in journal (Refereed)
    Abstract [en]

    Our aims were to measure anthropometric and oxygen uptake ((V)over dot O-2) variables in the laboratory, to measure kinetic and stride characteristics during a trail running time trial, and then analyse the data for correlations with trail running performance. Runners (13 men, 4 women: mean age: 29 +/- 5 years; stature: 179.5 +/- 0.8 cm; body mass: 69.1 +/- 7.4 kg) performed laboratory tests to determine (V)over dot O-2 (max), running economy (RE), and anthropometric characteristics. On a separate day they performed an outdoor trail running time trial (two 3.5 km laps, total climb: 486 m) while we collected kinetic and time data. Comparing lap 2 with lap 1 (19:40 +/- 1:57 min vs. 21:08 +/- 2:09 min, P < 0.001), runners lost most time on the uphill sections and least on technical downhills (-2.5 +/- 9.1 s). Inter-individual performance varied most for the downhills (CV > 25%) and least on flat terrain (CV < 10%). Overall stride cycle and ground contact time (GCT) were shorter in downhill than uphill sections (0.64 +/- 0.03 vs. 0.84 +/- 0.09 s; 0.26 +/- 0.03 vs. 0.46 +/- 0.90 s, both P < 0.001). Force impulse was greatest on uphill (248 +/- 46 vs. 175 +/- 24 Ns, P < 0.001) and related to GCT (r = 0.904, P < 0.001). Peak force was greater during downhill than during uphill running (1106 +/- 135 vs. 959 +/- 104 N, P < 0.01). Performance was related to absolute and relative (V)over dot O-2 (max) (P < 0.01), vertical uphill treadmill speed (P < 0.001) and fat percent (P < 0.01). Running uphill involved the greatest impulse per step due to longer GCT while downhill running generated the highest peak forces. (V)over dot O-2 (max), vertical running speed and fat percent are important predictors for trail running performance. Performance between runners varied the most on downhills throughout the course, while pacing resembled a reversed J pattern. Future studies should focus on longer competition distances to verify these findings and with application of measures of 3D kinematics.

  • 2.
    Bresin, Roberto
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Delle Monache, Stefano
    University of Verona.
    Fontana, Federico
    University of Verona.
    Papetti, Stefano
    University of Verona.
    Polotti, Pietro
    University of Verona.
    Visell, Yon
    McGill University.
    Auditory feedback through continuous control of crumpling sound synthesis2008In: Proceedings of Sonic Interaction Design: Sound, Information and Experience. A CHI 2008 Workshop organized by COST Action IC0601, IUAV University of Venice , 2008, p. 23-28Conference paper (Refereed)
    Abstract [en]

    A realtime model for the synthesis of crumpling sounds ispresented. By capturing the statistics of short sonic transients which give rise to crackling noise, it allows for a consistent description of a broad spectrum of audible physical processes which emerge in several everyday interaction contexts.The model drives a nonlinear impactor that sonifies every transient, and it can be parameterized depending on the physical attributes of the crumpling material. Three different scenarios are described, respectively simulating the foot interaction with aggregate ground materials, augmenting a dining scenario, and affecting the emotional content of a footstep sequence. Taken altogether, they emphasize the potential generalizability of the model to situations in which a precise control of auditory feedback can significantly increase the enactivity and ecological validity of an interface.

  • 3. Debevec, Tadej
    et al.
    McDonnell, Adam C.
    Macdonald, Ian A.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Mekjavic, Igor B.
    Whole body and regional body composition changes following 10-day hypoxic confinement and unloading-inactivity2014In: Applied Physiology, Nutrition and Metabolism, ISSN 1715-5312, E-ISSN 1715-5320, Vol. 39, no 3, p. 386-395Article in journal (Refereed)
    Abstract [en]

    Future planetary habitats will expose inhabitants to both reduced gravity and hypoxia. This study investigated the effects of short-term unloading and normobaric hypoxia on whole body and regional body composition (BC). Eleven healthy, recreationally active, male participants with a mean (SD) age of 24 (2) years and body mass index of 22.4 (3.2) kg.m(-2) completed the following 3 10-day campaigns in a randomised, cross-over designed protocol: (i) hypoxic ambulatory confinement (HAMB; FIO2 = 0.147 (0.008); PIO2 = 93.8 (0.9) mm Hg), (ii) hypoxic bed rest (HBR; FIO2 = 0.147 (0.008); PIO2 = 93.8 (0.9) mm Hg), and (iii) normoxic bed rest (NBR; FIO2 = 0.209; PIO2 = 133.5 (0.7) mmHg). Nutritional requirements were individually precalculated and the actual intake was monitored throughout the study protocol. Body mass, whole body, and regional BC were assessed before and after the campaigns using dual-energy X-ray absorptiometry. The calculated daily targeted energy intake values were 2071 (170) kcal for HBR and NBR and 2417 (200) kcal for HAMB. In both HBR and NBR campaigns the actual energy intake was within the targeted level, whereas in the HAMB the intake was lower than targeted (-8%, p < 0.05). Body mass significantly decreased in all 3 campaigns (-2.1%, -2.8%, and -2.0% for HAMB, HBR, and NBR, respectively; p < 0.05), secondary to a significant decrease in lean mass (-3.8%, -3.8%, -4.3% for HAMB, HBR, and NBR, respectively; p < 0.05) along with a slight, albeit not significant, increase in fat mass. The same trend was observed in the regional BC regardless of the region and the campaign. These results demonstrate that, hypoxia per se, does not seem to alter whole body and regional BC during short-term bed rest.

  • 4.
    Dubus, Gaël
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Evaluation of a system for the sonification of elite rowing in an interactive contextManuscript (preprint) (Other academic)
  • 5.
    Eriksson, Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics. Mid Sweden University, Sweden.
    Holmberg, H. -C
    Westerblad, H.
    A numerical model for fatigue effects in whole-body human exercise2015In: Mathematical and Computer Modelling of Dynamical Systems, ISSN 1387-3954, E-ISSN 1744-5051Article in journal (Refereed)
    Abstract [en]

    A physiology-based fatigue model was developed and tested, with the long-term objective to study optimal pacing strategies in cross-country skiing. The model considers both aerobic and anaerobic power contributions, with different demands for carbohydrate fuel. The fatigue model accumulates traces from anaerobic efforts, and dissipates fatigue exponentially. The current fatigue value affects the effective work rate output. A limited reservoir of fuel is considered. This paper discusses the numerical formulations. Examples show the relevance of the model for basic regimes of power output, and give qualitatively relevant results, but demonstrate the need for individual physiological parameters. Further examples study the model’s predictions with respect to interval training strategies, with conclusions on work rates and interval lengths.

  • 6.
    Eriksson, Martin
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Improving running mechanics by use of interactive sonification2010In: Proceedings of the Interaction Sonification workshop (ISon) 2010 / [ed] Bresin, Roberto; Hermann, Thomas; Hunt, Andy, Stockholm, Sweden: KTH Royal Institute of Technology, 2010, p. 95-98Conference paper (Refereed)
    Abstract [en]

    Running technique has a large effect on running economy interms of consumed amount of oxygen. Changing the naturalrunning technique, though, is a difficult task. In this paper, a method based on sonification is presented, that will assist the runner in obtaining a more efficient running style. The system is based on an accelerometer sending data to a mobile phone.Thus the system is non-obtrusive and possible to use in theeveryday training. Specifically, the feedback given is based on the runner’s vertical displacement of the center of mass. As this is the main source of energy expenditure during running, it is conjectured that a reduced vertical displacement should improve running economy.

  • 7.
    Eriksson, Martin
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Gullstrand, Lennart
    Swedish Sports Confederation.
    Wireless Vertical Displacement Measurement during Running using an Accelerometer and a Mobile Phone2011Conference paper (Refereed)
    Abstract [en]

    The purpose of this study was to investigate in the usability of a wireless accelerometer linked to a mobile phone via Bluetooth radio for measuring vertical displacement in running athletes. Five experienced runners were monitored during lactate threshold testing at three to five different velocities. Accelerometer data was received, processed and stored on the phone to be compared to simultaneous position transducer (ground truth) recordings after data collection. A paired t-test and statistical analysis show no significant differences in the reliability of the recordings. While further investigations are encouraged, the accelerometer and algorithm (running in J2ME on the mobile phone) proof as aflexible, easy-to-use tool for out-of-the-lab monitoring and to provide real-time feedback for running technique experiments.

  • 8. Fomin, Å.a
    et al.
    Da Silva, Cristina
    KTH, School of Technology and Health (STH). Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden.
    Ahlstrand, M.
    Sahlén, A.
    Lund, L.
    Stahlberg, M.
    Gabrielsen, A.
    Manouras, Aristomenis
    KTH, School of Technology and Health (STH). Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden.
    Gender differences in myocardial function and arterio-ventricular coupling in response to maximal exercise in adolescent floor-ball players2014In: BMC Sports Science, Medicine and Rehabilitation, ISSN 2052-1847, Vol. 6, no 1Article in journal (Refereed)
    Abstract [en]

    Background: The hemodynamic and cardiac responses to exercise have been widely investigated in adults. However, little is known regarding myocardial performance in response to a short bout of maximal exercise in adolescents. We therefore sought to study alterations in myocardial function and investigate sex-influences in young athletes after maximal cardiopulmonary testing. Methods: 51 adolescent (13-19 years old) floor-ball players (24 females) were recruited. All subjects underwent a maximal exercise test to determine maximal oxygen uptake (VO2max) and cardiac output. Cardiac performance was investigated using conventional and tissue velocity imaging, as well as 2D strain echocardiography before and 30 minutes following exercise. Arterio-ventricular coupling was evaluated by means of single beat ventricular elastance and arterial elastance. Results: Compared to baseline the early diastolic myocardial velocity (E’LV) at the basal left ventricular (LV) segments declined significantly (females: E’LV: 14.7 +/- 2.6 to 13.6 +/- 2.9 cm/s; males: 15.2 +/- 2.2 to 13.9 +/- 2.3 cm/s, p > 0.001 for both). Similarly, 2D strain decreased significantly following exercise (2D strain LV: from 21.5 +/- 2.4 to 20.2 +/- 2.7% in females, and from 20 +/- 1 to 17.9 +/- 1.5% in males, p > 0.05 for both). However, there were no significant changes in LV contractility estimated by elastance in either sex following exercise (p > 0.05). Arterial elastance) Ea) at baseline was identified as the only predictor of VO2max in males (r = 0.76, p < 0.001) but not in females (p > 0.05). Conclusions: The present study demonstrates that vigorous exercise of short duration results in a significant decrease of longitudinal myocardial motion in both sexes. However, in view of unaltered end systolic LV elastance (Ees), these reductions most probably reflect changes in the loading conditions and not an attenuation of myocardial function per se. Importantly, we show that arterial load at rest acts as a strong predictor of VO2max in males but not in female subjects.

  • 9.
    Frohm, Anna
    et al.
    Karolinska Institute.
    Halvorsen, Kjartan
    Swedish School of Sports and Helath Sciences.
    Thorstensson, Alf
    Swedish School of Sports and Health Sciences.
    A new device for controlled eccentric overloading in training and rehabilitation2005In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 94, no 1-2, p. 168-174Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to evaluate a device that allows for eccentric overload to be applied under controlled and safe conditions and it is applicable in exercises commonly used in training and rehabilitation. The machine contains a barbell, which is lowered and raised by a motor, following a predetermined velocity profile. It is capable of handling heavy loads (> 500 kg) and is instrumented with a sensor to measure the velocity of the barbell and two scales to measure the vertical component of the ground reaction force. The velocity recordings of the built-in displacement sensor were found to correspond well with those obtained using a motion-capture system. Applying known weights on each scale demonstrated linearity with respect to magnitude and independence regarding location of application. The velocity of the barbell was found to be dependent on the load on the barbell and on the resisting force produced by the individual training in the machine. The combined man-machine reliability was tested using a group of habitually active males (n = 13, 2855 years) performing squats. Peak voluntary resisting force and position at peak resistance were recorded on two occasions, showing no significant differences and a coefficient of variation of 9% and 22%, respectively. Preliminary observations from training in the machine have been positive both for increasing performance in top athletes and for causing pain relief in patients with diffuse knee problems. The possibility of feedback of the force under each foot makes individual dosage of training load possible, which is valuable, e.g. in rehabilitation of a unilateral injury.

  • 10.
    Frohm, Anna
    et al.
    Karolinska Institute.
    Halvorsen, Kjartan
    Swedish School of Sports and Health Sciences.
    Thorstensson, Alf
    Swedish School of Sports and Health Sciences.
    Patellar tendon load in different types of eccentric squats2007In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 22, no 6, p. 704-711Article in journal (Refereed)
    Abstract [en]

    Background. Differences in mechanical loading of the patellar tendon have been suggested as a reason for varying effects in rehabilitation of patellar tendinopathy using different eccentric squat exercises and devices. The aim was to characterize the magnitude and pattern of mechanical load at the knee and on the patellar tendon during four types of eccentric squat. Methods. Subjects performed squats with a submaximal free weight and with maximal effort in a device for eccentric overloading (Bromsman), on a decline board and horizontal surface. Kinematics was recorded with a motion-capture system, reaction forces with force plates, and electromyography from three leg muscles with surface electrodes. Inverse dynamics was used to calculate knee joint kinetics. Findings. Eccentric work, mean and peak patellar tendon force, and angle at peak force were greater (25-30%) for squats on decline board compared to horizontal surface with free weight, but not in Bromsman. Higher knee load forces (60-80%), but not work, were observed with Bromsman than free weight. Angular excursions at the knee and ankle were larger with decline board, particularly with free weight, and smaller in Bromsman than with free weight. Mean electromyography was greater on a decline board for gastrocnemius (13%) and vastus medialis (6%) with free weight, but in Bromsman only for gastrocnemius (7%). Interpretation. The results demonstrated clear differences in the biomechanical loading on the knee during different squat exercises. Quantification of such differences provides information that could be used to explain differences in rehabilitation effects as well as in designing more optimal rehabilitation exercises for patellar tendinopathy.

  • 11.
    Frohm, Anna
    et al.
    Karolinska Institute.
    Saartok, Tönuu
    Karolinska Institute.
    Halvorsen, Kjartan
    Swedish School of Sports and Health Sciences.
    Renström, Per
    Karolinska Institute.
    Eccentric treatment for patellar tendinopathy: a prospective randomised short-term pilot study of two rehabilitation protocols2007In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 41, no 7, p. e7-Article in journal (Refereed)
    Abstract [en]

    Objective: To compare the efficacy and safety of two eccentric rehabilitation protocols for patients with symptomatic patellar tendinopathy. A new eccentric overload training device was compared with the present standard eccentric rehabilitation programme on a decline board.Design: Prospective, randomised clinical trial.Setting: Sports rehabilitation clinic, university sports laboratory, supplemented with home exercises.Patients: 20 competitive and recreational athletes, all with clinical diagnosis of patellar tendinopathy, verified by MRI or ultrasound imaging.Interventions: A 12-week rehabilitation period, either with bilateral eccentric overload strength training using the Bromsman device twice a week or with unilateral eccentric body load training using a decline board twice a week, supplemented with daily home exercises.Outcome measures: The primary outcome was pain and function, assessed by the Swedish Victorian Institute of Sport Assessment for Patella (VISA-P) score. Secondary outcome measures were isokinetic muscle torque, dynamic function and muscle flexibility, as well as pain level estimations using visual analogue scale ( VAS). Side effects were registered.Results: Both treatment groups improved in the short term according to the VISA-P scores during the 12-week rehabilitation period. However, there were no significant differences between the groups in terms of pain and function. After a 3-month rehabilitation period, most patients could be regarded as improved enough to be able to return to training and sports. No serious side effects were detected in either group.Conclusion: In patients with patellar tendinopathy pain, two-legged eccentric overload training twice per week, using the new device ( Bromsman), was as efficient and safe as the present standard daily eccentric one-legged rehabilitation-training regimen using a decline board.

  • 12. Geladas, N.D.
    et al.
    Keramidas, Michail E.
    Performance tests: Laboratory fake or scientific reality?2005Conference paper (Other academic)
  • 13. Giordano, Bruno
    et al.
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Walking and playing: What's the origin of emotional expressiveness in music?2006In: Proceedings of the 9th International Conference on Music Perception & Cognition (ICMPC9), Bologna/Italy, August 22-26 2006 / [ed] Baroni, M.; Addessi, A. R.; Caterina, R.; Costa, M., Bologna: Bononia University Press, 2006, p. 436-Conference paper (Refereed)
  • 14.
    Halvorsen, Kjartan
    et al.
    The Swedish School of Sport and Health Sciences.
    Arndt, Anton
    The Swedish School of Sport and Health Sciences.
    Rosdahl, Hans
    The Swedish School of Sport and Health Sciences.
    Thorstensson, Alf
    The Swedish School of Sport and Health Sciences.
    Evaluation of three different models of the shoulder kinematics: application to kayak paddling2004In: Proceedings of ISB VIII International Symposium on the 3D Analysis of Human Movement, 2004Conference paper (Refereed)
  • 15.
    Halvorsen, Kjartan
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Brechbühl, Simon
    ETH Zurich, Switzerland.
    Minimal set of markers for center of mass estimation in gravitational fall2009In: Proceedings of the ISB XXII Congress, 2009Conference paper (Refereed)
  • 16.
    Halvorsen, Kjartan
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical Engineering.
    Gullstrand, Lennart
    Swedish Sports Confederation.
    Acute Effects Of Reducing Vertical Displacement And Step Frequency On Running Economy2012In: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 26, no 8, p. 2065-2070Article in journal (Refereed)
    Abstract [en]

    This work studies the immediate effects of altering the vertical displacement of CoM (VD) and step frequency (SF) on the metabolic cost of level treadmill running at 16 km·h on sixteen male runners. Alterations of VD, SF and the product VD SF was induced using a novel feedback system which presents target and current values to the runner by visual or auditory display. Target values were set to 5 and 10% reductions from individual baseline values. Results were expressed as relative changes from baseline values.Alterations led to an increase in metabolic cost in most cases, measured as VO2 uptake per minute and kg body mass. Correlations were weak. Still, linear multiple regression revealed a positive coefficient (0.28) for the relationship between VD SF and VO2. Separate rank correlation tests showed negative correlation (τ = -0.19) between SF and VO2 and positive correlation (τ = -0.16) between VD and VO2. There is a coupling between VD and SF caused by the mechanics of running, hence isolated reduction of either factor was hard to achieve. The linear model also showed a negative coefficient for the relationship between the height of center of mass above ground (CoMh) and VO2.The effect size was small (multiple R-squared 0.07 and 0.12). Still the results indicate that reducing VD SF by reducing vertical displacement can have a positive effect on running economy, but a concurrent reduction in CoMh may reduce or diminish the positive effect. Mid- and long-term effects of altering the technique should also be studied.

  • 17.
    Halvorsen, Kjartan
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Nilsson, Johnny
    The Swedish School of Sport and Health Sciences.
    Tinmark, Fredrik
    The Swedish School of Sport and Health Sciences.
    Gullstrand, Lennart
    The Swedish Sport Confederation.
    The antero-posterior movement of the sacrum as an indicator of the antero-posterior movement of center of mass in running2011In: Proceedings of ECSS 16th Congress, 2011Conference paper (Refereed)
  • 18.
    Halvorsen, Kjartan
    et al.
    The Swedish School of Sport and Health Sciences.
    Frohm, Anna
    Karolinska Institute.
    Thorstensson, Alf
    The Swedish School of Sport and Health Sciences.
    The influence of declined support surface on the biomechanics of eccentric overload in squats2005In: Proceedings of the ISB XX Congress, 2005Conference paper (Refereed)
  • 19.
    Harringe, Marita
    et al.
    Karolinska Institute.
    Halvorsen, Kjartan
    Swedish School of Sports and Health Sciences.
    Renström, Per
    Karolinska Institute.
    Werner, Suzanne
    Karolinska Institute.
    Postural control measured as the center of pressure excursion in young female gymnasts with low back pain or lower extremity injury2008In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 28, p. 38-45Article in journal (Refereed)
  • 20.
    Jönhagen, Sven
    et al.
    Karolinska Institute.
    Halvorsen, Kjartan
    Swedish School of Sports and Health Sciences.
    Benoit, Daniel L
    Karolinska Institute.
    Muscle activation and length changes during two lunge exercises: implications for rehabilitation2009In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Scand J Med Sc Sports, Vol. 19, p. 561-568Article in journal (Refereed)
    Abstract [en]

    Eccentric exercises are commonly used as a treatment for various muscle and tendon injuries. During complex motions such as the forward lunge, however, it is not always clear which muscles may be contracting eccentrically and at what time. Because this exercise is used during rehabilitation, the purpose of this investigation was to determine what type of contractions take place during two different types of forward lunge and assess the implications for rehabilitation. Five experienced athletes performed five cycles for each of the walking and jumping forward lunges. Motion analysis was used to calculate the shortening or elongation of each muscle based on the change of position of their origin and insertion points during the lunge. Electromyography of the lateral hamstrings, rectus femoris and lateral gastrocnemius was combined with the muscle length change data to determine when isometric, concentric and eccentric activations occur during the lunge. Eccentric contractions in both the quadriceps and gastrocnemius were observed during the lunge. No hamstring eccentric contractions were found; however, the hamstrings showed isometric contractions during the first part of the stance phase.

  • 21.
    Keramidas, Michail E.
    et al.
    Jozef Stefan Institute, Slovenia; Jozef Stefan International Postgraduate School, Slovenia .
    Debevec, T
    Amon, M
    Kounalakis, S.N.
    Simunic, B
    Mekjavic, I.B.
    Respiratory muscle endurance training: Effect on normoxic and hypoxic exercise performance2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 108, no 4, p. 759-769Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the effect of respiratory muscle endurance training on endurance exercise performance in normoxic and hypoxic conditions. Eighteen healthy males were stratified for age and aerobic capacity; and randomly assigned either to the respiratory muscle endurance training (RMT = 9) or to the control training group (CON = 9). Both groups trained on a cycle-ergometer 1 h day(-1), 5 days per week for a period of 4 weeks at an intensity corresponding to 50% of peak power output. Additionally, the RMT group performed a 30-min specific endurance training of respiratory muscles (isocapnic hyperpnea) prior to the cycle ergometry. Pre, Mid, Post and 10 days after the end of training period, subjects conducted pulmonary function tests (PFTs), maximal aerobic tests in normoxia ((V) over dotO(2max)NOR), and in hypoxia ((V) over dotO(2max)HYPO; F(I)O(2) = 0.12); and constant-load tests at 80% of (V) over dotO(2max)NOR in normoxia (CLT(NOR)), and in hypoxia (CLT(HYPO)). Both groups enhanced (V) over dotO(2max)NOR (CON: +13.5%; RMT: +13.4%), but only the RMT group improved (V) over dotO(2max)HYPO Post training (CON: -6.5%; RMT: +14.2%). Post training, the CON group increased peak power output, whereas the RMT group had higher values of maximum ventilation. Both groups increased CLT(NOR) duration (CON: +79.9%; RMT: +116.6%), but only the RMT group maintained a significantly higher CLT(NOR) 10 days after training (CON: +56.7%; RMT: +91.3%). CLT(HYPO) remained unchanged in both groups. Therefore, the respiratory muscle endurance training combined with cycle ergometer training enhanced aerobic capacity in hypoxia above the control values, but did not in normoxia. Moreover, no additional effect was obtained during constant-load exercise.

  • 22. Keramidas, Michail E.
    et al.
    Geladas, N.D.
    Performance Tests: Design and Analysis2008In: Hellenic Journal of Physical Education and Sport, Vol. 69, p. 48-67Article in journal (Refereed)
  • 23. Keramidas, Michail E.
    et al.
    Geladas, N.D.
    Performance Tests: “Detecting the change”2008In: Hellenic Journal of Physical Education and Sport, Vol. 69, p. 14-24Article, review/survey (Refereed)
  • 24. Keramidas, Michail E.
    et al.
    Geladas, N.D.
    Training load: how enough is the enough?2005Conference paper (Other academic)
  • 25. Keramidas, Michail E.
    et al.
    Kounalakis, S.N.
    Anastassopoulos, S.
    Nassis, G.P.
    Koskolou, M.
    Geladas, N.D.
    The effect of high-intensity interval training combined with application of external pressure on thighs on peak power output2006Conference paper (Refereed)
  • 26.
    Keramidas, Michail E.
    et al.
    University of Athens, Greece.
    Kounalakis, S.N.
    Nassis, G.P.
    Koskolou, M.
    Geladas, N.D.
    Effect of high-intensity interval training on maximal and submaximal performance2006Conference paper (Refereed)
  • 27.
    Keramidas, Michail E.
    et al.
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Mekjavic, Igor B.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Hand temperature responses to local cooling after a 10-day confinement to normobaric hypoxia with and without exercise2015In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 25, no 5, p. 650-660Article in journal (Refereed)
    Abstract [en]

    The study examined the effects of a 10-day normobaric hypoxic confinement (FiO2: 0.14), with (HT; n = 8) or without (HA; n = 6) exercise, on the hand-temperature responses during and after local cold stress. Before and after the confinement, subjects immersed their right hand for 30 min in 8°C water (CWI), followed by a 15-min spontaneous rewarming (RW), while breathing either room air (AIR), or a hypoxic gas mixture (HYPO). The hand-temperature responses were monitored with thermocouples and infrared-thermography. The confinement did not influence the hand-temperature responses of the HA group during the AIR and HYPO CWI and the HYPO RW phases; but it impaired the AIR RW response (-1.3°C; P = 0.05). After the confinement, the hand-temperature responses were unaltered in the HT group throughout the AIR trial. However, the average hand-temperature was increased during the HYPO CWI (+0.5°C; P ≤ 0.05) and RW (+2.4°C; P ≤ 0.001) phases. Accordingly, present findings suggest that prolonged exposure to normobaric hypoxia per se does not alter the hand-temperature responses to local cooling; yet, it impairs the normoxic rewarming response. Conversely, the combined stimuli of continuous hypoxia and exercise enhance the finger cold-induced vasodilatation and hand-rewarming responses, specifically, under hypoxic conditions.

  • 28.
    Keramidas, Michail E.
    et al.
    Jozef Stefan Institute, Slovenia; Jozef Stefan International Postgraduate School, Slovenia .
    Musizza, B
    Kounalakis, S.N.
    Mekjavic, I.B.
    Enhancement of the finger cold-induced vasodilation response with exercise training2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 109, no 1, p. 133-140Article in journal (Refereed)
    Abstract [en]

    Cold-induced vasodilatation (CIVD) is a cyclical increase in finger temperature that has been suggested to provide cryoprotective function during cold exposures. Physical fitness has been suggested as a potential factor that could affect CIVD response, possibly via central (increased cardiac output, decreased sympathetic nerve activity) and/or peripheral (increased microcirculation) cardiovascular and neural adaptations to exercise training. Therefore, the purpose of this study was to investigate the effect of endurance exercise training on the CIVD response. Eighteen healthy males trained 1 h d(-1) on a cycle ergometer at 50% of peak power output, 5 days week(-1) for 4-weeks. Pre, Mid, Post, and 10 days after the cessation of training and on separate days, subjects performed an incremental exercise test to exhaustion ((V) over dotO(2peak)); and a 30-min hand immersion in 8 degrees C water to examine their CIVD response. The exercise-training regimen significantly increased (V) over dotO(2peak) (Pre: 46.0 +/- 5.9, Mid: 52.5 +/- 5.7, Post: 52.1 +/- 6.2, After: 52.6 +/- 7.6 ml kg(-1) min-1; P < 0.001). There was a significant increase in average finger skin temperature (Pre: 11.9 +/- 2.4, After: 13.5 +/- 2.5 degrees C; P < 0.05), the number of waves (Pre: 1.1 +/- 1.0, After: 1.7 +/- 1.1; P < 0.001) and the thermal sensation (Pre: 1.7 +/- 0.9, After: 2.5 +/- 1.4; P < 0.001), after training. In conclusion, the aforementioned endurance exercise training significantly improved the finger CIVD response during cold-water hand immersion.

  • 29.
    Keramidas, Michail E.
    et al.
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology. KTH, School of Technology and Health (STH), Centres, Swedish Aerospace Physiology Centre, SAPC. Jozef Stefan Institute, Slovenia.
    Stavrou, Nektarios A.M.
    Kounalakis, Stylianos D.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology. KTH, School of Technology and Health (STH), Centres, Swedish Aerospace Physiology Centre, SAPC.
    Igor B., Mekjavic
    Severe hypoxia during incremental exercise to exhaustion provokes negative post-exercise affects2016In: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 156Article in journal (Refereed)
    Abstract [en]

    The post-exercise emotional response is mainly dependent on the intensity of the exercise performed; moderate exercise causes positive feelings, whereas maximal exercise may prompt negative affects. Acute hypoxia impairs peak O2 uptake (VO2peak), resulting in a shift to a lower absolute intensity at the point of exhaustion. Hence, the purpose of the study was to examine whether a severe hypoxic stimulus would influence the post-exercise affective state in healthy lowlanders performing an incremental exercise to exhaustion. Thirty-six male lowlanders performed, in a counter-balanced order and separated by a 48-h interval, two incremental exercise trials to exhaustion to determine their VO2peak, while they were breathing either room air (AIR; FiO2: 0.21), or a hypoxic gas mixture (HYPO; FiO2: 0.12). Before and immediately after each trial, subjects were requested to complete two questionnaires, based on how they felt at that particular moment: (i) the Profile of Mood States-Short Form, and (ii) the Activation Deactivation Adjective Check List. During the post-exercise phase, they also completed the Multidimensional Fatigue Inventory. VO2peak was significantly lower in the HYPO than the AIR trial (~15%; p<0.001). Still, after the HYPO trial, energy, calmness and motivation were markedly impaired, whereas tension, confusion, and perception of physical and general fatigue were exaggerated (p≤0.05). Accordingly, present findings suggest that an incremental exercise to exhaustion performed in severe hypoxia provokes negative post-exercise emotions, induces higher levels of perceived fatigue and decreases motivation; the affective responses coincide with the comparatively lower VO2peak than that achieved in normoxic conditions.

  • 30. Kounalakis, S. N.
    et al.
    Keramidas, Michail E.
    Nassis, G.P
    Geladas, N.D.
    The role of muscle pump in the development of cardiovascular drift2008In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 103, p. 99-107Article in journal (Refereed)
    Abstract [en]

    This study examined the role of muscle pump in the development of cardiovascular drift (CVdrift) during cycling. Twelve healthy males (23.4 ± 0.5 years, mean ± SE) exercised for 90 min with 40 and 80 pedal revolutions per minute (rpm) at the same oxygen consumption, in two separate days. CVdrift was developed in both conditions as indicated by the drop in stroke volume (SV) and the rise in heart rate (HR) from the 20th min onwards (ΔSV = −16.2 ± 2.0 and −17.1 ± 1.0 ml beat−1; ΔHR = 18.3 ± 2.0 and 17.5 ± 3.0 beats min−1 for 40 and 80 rpm, respectively, P < 0.05) but without difference between conditions. Mean cardiac output (CO2 rebreathing) was 14.7 ± 0.3 l min−1 and 15.0 ± 0.3 l min−1, and mean arterial pressure was 100.0 ± 1.0 mmHg and 96.7 ± 0.8 mmHg for 40 and 80 rpm, respectively, without significant changes over time, and without difference between conditions. Electromyographic activity (iEMG) was lower throughout exercise with 80 rpm (35.6 ± 1.2% and 11.0 ± 1.0% for 40 and 80 rpm, respectively). Similarly, total hemoglobin, determined with near-infrared spectroscopy (NIRS) was 58.0 ± 0.8 (AU) for 40 rpm and 53.0 ± 1.4 (arbitrary units) for 80 rpm, from 30th min onwards (P < 0.05), an indication of lower leg blood volume during the faster pedal rate condition. Thermal status (rectal and mean skin temperature), blood and plasma volume changes, blood lactate concentration, muscle oxygenation (NIRS signal) and the rate of perceived exertion were similar in the two trials. It seems that muscle pump is not an important factor for the development of CVdrift during cycling, at least under the present experimental conditions

  • 31.
    McDonnell, Adam C.
    et al.
    Jozef Stefan Inst, Jozef Stefan Int Postgrad Sch, Ljubljana, Slovenia..
    Stavrou, Nektarios A. M.
    ASPETAR Orthopaed & Sports Med Hosp, Doha, Qatar..
    Eiken, Ola
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Environmental Physiology.
    Mekjavic, Igor B.
    Jozef Stefan Inst, Ljubljana, Slovenia..
    The Effect Of A Live-high Train-high Regimen On Emotional State2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 5, p. 608-608Article in journal (Other academic)
  • 32.
    Norrbrand, Lena
    et al.
    Karolinska Institutet, Department of Physiology and Phamacology.
    Tous-Fajardo, Julio
    Vargas, Roberto
    Tesch, Per A.
    Quadriceps muscle use in the flywheel and barbell squat2011In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 82, no 1, p. 13-19Article in journal (Refereed)
    Abstract [en]

    Background: Resistance exercise has been proposed as an aid to counteract quadriceps muscle atrophy in astronauts during extended missions in Orbit. While space authorities have advocated the squat exercise should be prescribed, no exercise system suitable for in-flight use has been validated with regard to quadriceps muscle use. We compared muscle involvement in the terrestrial “gold standard” squat using free weights and a non-gravity dependent flywheel resistance exercise device aimed at use in space. Methods: Ten strength-trained men performed five sets of 10 repetitions using the Barbell Squat (BS; 10 repetition maximum) or Flywheel Squat (FS; each repetition maximal), respectively. Functional magnetic resonance imaging (MRI) and surface electromyography (EMG) techniques assessed quadriceps muscle use. Exercise-induced contrast shift of MR images was measured by means of transverse relaxation time (T2). EMG root mean square (RMS) was measured during concentric (CON) and eccentric (ECC) actions and normalized to EMG RMS determined during maximal voluntary contraction. Results: The quadriceps muscle group showed greater exercise-induced T2 increase following FS compared with BS. Among individual muscles, the rectus femoris displayed greater T2 increase with FS (+24±14%) than BS (+8±4%). Normalized quadriceps EMG showed no difference across exercise modes. Discussion: Collectively, the results of this study suggest that quadriceps muscle use in the squat is comparable, if not greater, with flywheel compared with free weight resistance exercise. Data appears to provide support for use of flywheel squat resistance exercise as a countermeasures adjunct during spaceflight.

  • 33. Salvadego, Desy
    et al.
    Keramidas, Michail E.
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Brocca, Lorenza
    Domenis, Rossana
    Mavelli, Irene
    Rittweger, Jörn
    Eiken, Ola
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Mekjavic, Igor B.
    Grassi, Bruno
    LunHab: Separate and combined effects of a 10-d exposure to hypoxia and inactivity on oxidative function in vivo and mitochondrial respiration ex vivo in humans.2016In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 121, no 1Article in journal (Refereed)
    Abstract [en]

    An integrative evaluation of oxidative metabolism was carried out in 9 healthy young men (age, 24.1 +/- 1.7 yr mean +/- SD) before (CTRL) and after a 10-day horizontal bed rest carried out in normoxia (N-BR) or hypoxia (H-BR, FIO2 = 0.147). H-BR was designed to simulate planetary habitats. Pulmonary O-2 uptake ((V) over dotO(2)) and vastus lateralis fractional O-2 extraction (changes in deoxygenated hemoglobin + myoglobin concentration, Delta[deoxy(Hb + Mb)] evaluated using near-infrared spectroscopy) were evaluated in normoxia and during an incremental cycle ergometer (CE) and one-leg knee extension (KE) exercise (aimed at reducing cardiovascular constraints to oxidative function). Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in permeabilized vastus lateralis fibers. During CE (V) over dotO(2peak) and Delta[deoxy(Hb + Mb)] peak were lower (P < 0.05) after both N-BR and H-BR than during CTRL; during KE the variables were lower after N-BR but not after H-BR. During CE the overshoot of Delta[deoxy(Hb + Mb)] during constant work rate exercise was greater in N-BR and H-BR than CTRL, whereas during KE a significant difference vs. CTRL was observed only after N-BR. Maximal mitochondrial respiration determined ex vivo was not affected by either intervention. In N-BR, a significant impairment of oxidative metabolism occurred downstream of central cardiovascular O-2 delivery and upstream of mitochondrial function, possibly at the level of the intramuscular matching between O-2 supply and utilization and peripheral O-2 diffusion. Superposition of hypoxia on bed rest did not aggravate, and partially reversed, the impairment of muscle oxidative function in vivo induced by bed rest. The effects of longer exposures will have to be determined.

  • 34. Salvadego, Desy
    et al.
    Keramidas, Michail E.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Domenis, Rossana
    Mavelli, Irene
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Mekjavic, Igor B.
    Grassi, Bruno
    Combined Effects of Bed Rest and Hypoxia on Skeletal Muscle Oxidative Function2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, p. 111-111Article in journal (Other academic)
  • 35.
    Sturm, Dennis
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Parida, Vinit
    Luleå University of Technology.
    Larsson, Tobias C.
    Luleå University of Technology.
    Isaksson, Ola
    Luleå University of Technology.
    Design of user-centred wireless sensor technology in sports: An empirical study of elite kayak athletes2011Conference paper (Refereed)
    Abstract [en]

    University research is demanded to be more need-driven and user-centred in order to address and solve problems and needs of the market. In the present study a group of athletes and coaches has been analysed on their lead user characteristics. Some of the lead users have contributed with advanced user insights and aidin trend foresight in this sport. In a combined qualitative and quantitative approach the value of lead users in sports technology was examined and four users were identified as lead users. In consistence with previous research the results indicate that involving lead users will foster superior insight and research.

  • 36.
    Sturm, Dennis
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Yousaf, Khurram
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). Uppsala University, Uppsala, Sweden .
    Wireless kayak on-water ergometry - Part 1: Paddle blade force2013In: Sports Technology, ISSN 1934-6182, E-ISSN 1934-6190, Vol. 6, no 1, p. 29-42Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to present a new wireless paddle force measurement system and to evaluate this measurement system. The system is redeveloped from a previous design and includes inertial motion sensors, which allows for the movement and inertia of the paddle to be taken into account. The system consists of two sensor nodes, designed for quick attachment to virtually any kayak paddle and an Android phone or tablet. Each sensor node measures the bending of the shaft in one plane. We derive the expressions necessary for computing the force on the paddle blade in two directions, ignoring the force in the direction of the shaft. Two different schemes for calibrating the system are presented. The accuracy and reliability of the system is evaluated in a laboratory setting using a material testing machine. An average error of 0.4% can be achieved for force measurements following directly after calibration. When the sensors are removed and reattached between calibration and measurements, average error between loading and measured force increased to 2.0% (linear model) and 1.8% (quadratic model). The limits of agreement depend on the position of the sensor nodes along the shaft and the feather angle if transverse sensitivity of the sensors is used to determine two-dimensional force on the paddle blade. On-water stroke force is presented, averaged over 10 strokes for each side with force levels >200 N to show the applicability of the study. The accuracy of the measurement is affected by the calibration method, placement of the paddle nodes and the shaft's properties.

  • 37.
    Sturm, Dennis
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Yousaf, Khurram
    KTH, School of Technology and Health (STH), Medical Engineering.
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical Engineering.
    A Kayak Training System for Force Measurement on-water2010Conference paper (Refereed)
    Abstract [en]

    Kayaking is a very competitive sport and represented in the Olympic context with two disciplines: slalom and flatwater. The main forces that propel the boat are paddle and foot stretcher force (Mann & Kearney, 1980). Anecdotal evidence collected from coaches involved in the research suggests varying theories on the best profile and synchronisation of paddle and foot stretcher force. It should be extremely helpful for athletes, coaches and researchers to measure these forces in real-time on-water with an unobtrusive, wireless sensor system such as is presented here. Thereby athletes are provided the possibility to perform their training with knowledge of performance (KP), which leads to superior training effects compared to knowledge of results (KR) only. The authors have not been able to identify any previous studies examining paddle and foot stretcher forces simultaneously although previous work has suggested doing so (Michael et al. 2009, Petrone et al., 1998).

  • 38.
    Sturm, Dennis
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Yousaf, Khurram
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    A wireless, unobtrusive Kayak Sensor Network enabling Feedback Solutions2010In: 2010 International Conference on Body Sensor Networks, BSN 2010, 2010, p. 159-163Conference paper (Refereed)
    Abstract [en]

    Canoeing is a very competitive sport involving a non-trivial pattern of motion. A group of athletes and coaches approached the authors for aid in quantifying what until today only is qualitative, personal and thereby subjective data. The objective of this work is to present a measurement tool that records paddle and foot stretcher force in a flatwater kayak training situation, i.e. when training on the water. The system facilitatesa wireless (Bluetooth) star network link with three sensor nodes and one central unit. Validation data was obtained from a kayak ergometer that is equipped with analysis software. The stroke power obtained from this ergometer system is compared to the force data measured by the presented wireless sensor nodes. We have not been able to find any similar systems that would provide better data for performance analysis.

  • 39.
    Sturm, Dennis
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Yousaf, Khurram
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Tornberg, Åsa B.
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Validation of a novel wireless Force Measurement System for Kayak Paddle ShaftsManuscript (preprint) (Other academic)
  • 40.
    Sturm, Dennis
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Yousaf, Khurram
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Håkansson, Paul
    Lund University.
    Segerström, Åsa
    Lund University.
    Measuring Kayak Paddle Performance with Wireless Strain Sensors on the Shaft: A Validation Study2011Conference paper (Refereed)
  • 41.
    Svensson, Daniel
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, History of Science, Technology and Environment.
    Technologies of sportification: Practice, Theory and Co-Production of Training Knowledge in Cross-Country Skiing Since the 1950s2016In: European Studies in Sports History, Vol. 9, no 1Article in journal (Refereed)
    Abstract [en]

    Elite athletes of today use specialized, scientific training methods and the increasing role of science in sports is undeniable. The scientization process started in endurance sports (e.g. Yttergren 2012, Bourne 2008, Krüger 2006, Svensson 2014, Heggie 2011, Johnson 2009), among them cross-country skiing. This article analyzes how Swedish physiologists and cross-country skiers interacted in the scientization of training methods, focusing on the technologies of sportification that were used. Examples of such technologies are scientific testing, training logs, training camps and training manuals. Material from archives, interviews and earlier research will be studied using theories of bio-power (Foucault 1998) and sportification (e.g. Yttergren 2006, Guttmann 1978). The article concludes that while technologies of sportification could not ensure a rapid rationalization of training methods, these technologies over time became standard features in the training and sportification of cross-country skiing.

  • 42.
    Swarén, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics. Royal Inst Technol, Dept Mech, Stockholm, Sweden..
    Eriksson, Anders
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Power and pacing calculations based on real-time locating data from a cross-country skiing sprint race2019In: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 18, no 2, p. 190-201Article in journal (Refereed)
    Abstract [en]

    Pacing strategies in cross-country skiing have been investigated in several studies. However, none of the previous studies have been verified by collected skiing data giving the skiing velocities along a measured track. These can be used to calculate the propulsive power output. Collected real-time positioning data from a cross-country sprint skiing race were used to estimate the propulsive power by applying a power balance model. Analyses were made for the time-trial and the final for one female and one male skier. The average propulsive power over the whole race times were 311 and 296 W during the time trial and 400 and 386 W during the final, for the female and male skier, respectively. Compared to the average propulsive power over the whole race, the average active propulsive phases were calculated as 33 and 44% higher in the time trials and 36 and 37% higher in the finals for the female and male, respectively. The current study presents a novel approach to use real-time positioning data to estimate continuous propulsive power during cross-country sprint skiing, enabling in-depth analyses of power output and pacing strategies.

  • 43.
    Tinmark, Fredrik
    et al.
    The Swedish School of Sport and Health Sciences.
    Hellström, John
    The Swedish School of Sport and Health Sciences.
    Halvorsen, Kjartan
    The Swedish School of Sport and Health Sciences.
    Thorstensson, Alf
    The Swedish School of Sport and Health Sciences.
    Analysis of elite golfers' kinematic sequence in full-swing and partial swing shots2009In: Proceedings of ISBS 27 International Conference on Biomechanics in Sports, 2009Conference paper (Refereed)
    Abstract [en]

    Proximal-to-distal sequencing (PDS) has been observed in full-swing golf shots as in most throwing and striking skills, where the main goal is to maximize speed in the most distal segment of an open-link system (Zheng et al., 2007). Although PDS primarily is associated with mechanical advantage when the speed requirement is high, this temporal order has also been found and ascribed various merits in relatively slow multi-joint movements (Furuya & Kinoshita, 2007). However, no research to date has examined the sequencing pattern in partial golf shots to submaximal distances. The purpose here was to investigate whether PDS is a common characteristic also in partial swing shots of skilled golf players. METHODS: A total of 47 golfers were investigated, 11 male tournament professionals, 23 male amateurs (HCP 0 ± 2 strokes), and 13 female amateurs (HCP -2 ± 2 strokes) performed partial shots with a wedge to targets at three discrete distances (40, 55 and 70 m), and full-swing shots with a five iron as well as a driver in the same direction for maximal distance. Pelvis, upper torso, and hand movement were recorded in 3D with an electromagnetic tracking system (Polhemus) at 240 Hz. The magnitude of the resultant angular velocity vector of each segment was used to examine the sequencing pattern and the angular speed of segment motions. Movement onset, peak amplitude and time for peak amplitude were analyzed in separate repeated-measure ANOVAs with pre-planned Bonferroni corrected pairwise comparisons.

  • 44. Tinmark, Fredrik
    et al.
    Hellström, John
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical Engineering.
    Thorstensson, Alf
    Elite golfers' kinematic sequence in full-swing and partial-swing shots2010In: SPORT BIOMECH, ISSN 1476-3141, Vol. 9, no 4, p. 236-244Article in journal (Refereed)
    Abstract [en]

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

  • 45.
    Tinmark, Fredrik
    et al.
    The Swedish School of Sport and Health Sciences.
    Hellström, John
    Örebro University.
    Thorstensson, Alf
    The Swedish School of Sport and Health Sciences.
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Contributions to endpoint velocity in a bimanual striking task2011In: Proceedings of ISB XXIII Congress, 2011Conference paper (Refereed)
  • 46. Visell, Y.
    et al.
    Fontana, F.
    Giordano, B. L.
    Nordahl, R.
    Serafin, S.
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Sound design and perception in walking interactions2009In: International journal of human-computer studies, ISSN 1071-5819, E-ISSN 1095-9300, Vol. 67, no 11, p. 947-959Article in journal (Refereed)
    Abstract [en]

    This paper reviews the state of the art in the display and perception of walking generated sounds and tactile vibrations, and their current and potential future uses in interactive systems. As non-visual information sources that are closely linked to human activities in diverse environments, such signals are capable of communicating about the spaces we traverse and activities we encounter in familial and intuitive ways However, in order for them to be effectively employed in human-computer interfaces, significant knowledge is required in areas including the perception of acoustic signatures of walking, and the design, engineering, and evaluation of interfaces that utilize them. Much of this expertise has accumulated in recent years, although many questions remain to be explored We highlight past work and current research directions in this Multidisciplinary area of investigation, and point to potential future trends.

  • 47. Westman, Anton
    et al.
    Georen, Peter
    Stromberg, Johan
    Inclined Wind Tunnel for the Study of Human and Large Animal Flight2017In: Wilderness & environmental medicine (Print), ISSN 1080-6032, E-ISSN 1545-1534, Vol. 28, no 1, p. 54-56Article in journal (Refereed)
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