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  • 1.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Ainegren, Mats
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Work economy of amateur and elite cross-country skiers during treadmill roller skiing2009In: 4th Asia Pacific Congress on Sports Technology, APCST2009, 2009Conference paper (Refereed)
    Abstract [en]

    This study focused on the work economy of cross-country skiers during treadmill roller skiing in the perspectives; skill, age and gender. The study was investigating the external power output from elevating the transported mass against gravity and overcoming the roller skis rolling resistance, and the internal power from measured oxygen uptake and energy consumption. The roller skis rolling resistance was measured with a fixture on the ski-treadmill and the results showed a significant correlation between normal force and rolling resistance. The results also showed that it was only the amateur skiers who significantly differed in work economy among the five studied groups.

  • 2.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Laaksonen, Marko S.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    The influence of grip on oxygen consumption and leg forces when using classical style roller skis2014In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, no 2, p. 301-310Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the influence of classical style roller skis' grip (static friction coefficients, μ S) on cross-country skiers' oxygen consumption and leg forces during treadmill roller skiing, when using the diagonal stride and kick double poling techniques. The study used ratcheted wheel roller skis from the open market and a uniquely designed roller ski with an adjustable camber and grip function. The results showed significantly (P≤0.05) higher oxygen consumption (∼14%), heart rate (∼7%), and lower propulsive forces from the legs during submaximal exercise and a shorter time to exhaustion (∼30%) in incremental maximal tests when using roller skis with a μ S similar to on-snow skiing, while there was no difference between tests when using different pairs of roller skis with a similar, higher μ S. Thus, we concluded that oxygen consumption (skiing economy), propulsive leg forces, and performance time are highly changed for the worse when using roller skis with a lower μ S, such as for on-snow skiing with grip-waxed cross-country skis, in comparison to ratcheted wheel roller skis with several times higher μ S.

  • 3.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Laaksonen, Marko S.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Skiing economy and efficiency in recreational and elite cross-country skiers2013In: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 27, no 5, p. 1239-1252Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate and compare skiing economy and gross efficiency in cross-country skiers of different performance levels, ages and genders; male recreational skiers and elite senior and junior cross-country skiers of both genders. The skiers performed tests involving roller skiing on a treadmill using the gear 3 and diagonal stride techniques. The elite crosscountry skiers were found to have better skiing economy and higher gross efficiency (5-18%) compared with the recreational skiers (p < 0.05) and the senior elite had better economy and higher efficiency (4-5%) than their junior counterparts (p < 0.05), whereas no differences could be found between the genders. Also, large ranges in economy and gross efficiency were found in all groups. It was concluded that, in addition to v̇O2peak, skiing economy and gross efficiency have a great influence on the differences in performance times between recreational and junior and senior elite cross-country skiers, as well as between individual skiers within the different categories. Thus, we recommend crosscountry skiers at all performance levels to test not only v̇O2peak, but also skiing economy and efficiency.

  • 4.
    Björklund, Glenn
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, H. -C
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Blood lactate recovery and respiratory responses during diagonal skiing of variable intensity2011In: European Journal of Sport Science, ISSN 1746-1391, E-ISSN 1536-7290, Vol. 11, no 5, p. 317-326Article in journal (Refereed)
    Abstract [en]

    The aims of the study were to investigate blood lactate recovery and respiratory variables during diagonal skiing of variable intensity in skiers at different performance levels. Twelve male cross-country skiers classified as elite (n=6; VO2max=73±3 ml. kg-1. min-1) or moderately trained (n=6; VO2max=61±5 ml. kg-1. min-1) performed a 48-min variable intensity protocol on a treadmill using the diagonal stride technique on roller skis, alternating between 3 min at 90% and 6 min at 70% of VO2max. None of the moderately trained skiers were able to complete the variable intensity protocol and there was a difference in time to exhaustion between the two groups (elite: 45.0±7.3 min; moderately trained: 31.4±10.4 min) (P&lt;0.05). The elite skiers had lower blood lactate concentrations and higher blood base excess concentrations at all 70% workloads than the moderately trained skiers (all P&lt;0.05). In contrast, VE/VO2 and VE/VCO2 at the 70% VO2max workloads decreased independently of group (P&lt;0.05). Partial correlations showed that VO2max was related to blood lactate at the first and second intervals at 70% of VO2max (r=-0.81 and r=-0.82; both P&lt;0.01) but not to VE/VO2, VE/VCO2 or the respiratory exchange ratio. Our results demonstrate that during diagonal skiing of variable intensity, (1) elite skiers have superior blood lactate recovery compared with moderately trained skiers, who did not show any lactate recovery at 70% of VO2max, suggesting it is an important characteristic for performance; and (2) the decreases in respiratory exchange ratio, VE/VO2, and VE/VCO2 do not differ between elite and moderately trained skiers.

  • 5.
    Carlsson, Lars
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lind, Britta
    Royal Inst Technol KTH, Sch Technol & Hlth, Stockholm, Sweden .
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Berglund, Bo
    Karolinska Inst, Dept Internal Med, S-10401 Stockholm, Sweden.
    Brodin, Lars-Åke
    Royal Inst Technol KTH, Sch Technol & Hlth, Stockholm, Sweden .
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Enhanced systolic myocardial function in elite endurance athletes during combined arm-and-leg exercise2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 6, p. 905-913Article in journal (Refereed)
    Abstract [en]

    The aim here was to employ color tissue velocity imaging (TVI), to test the hypothesis that highly trained endurance athletes exhibit enhanced systolic function of the left ventricular (LV) myocardium both at rest and during combined arm-and-leg exercise in comparison with untrained subjects. For each of the ten elite male (EG) and ten matched control participants (CG), LV dimensions and systolic function were assessed at rest using echocardiography. Subsequently, these subjects exercised continuously on a combined arm-and-leg cycle ergometer for 3 min each at 50, 60, 70, 80, 90 and 100% of VO2max. Oxygen uptake, heart rate, systolic blood pressure (SBP) and peak contraction systolic velocities of the LV myocardium (PSV) were recorded in the end of each level. At rest, the trained and untrained groups differed with respect to LV dimensions, but not systolic function. At 60–100% VO2max, the EG group demonstrated both higher PSV and SBP. The observation that the EG athletes had higher PSV than CG during exercise at 60–100% VO2max, but not at rest or at 50% of VO2max, suggested an enhanced systolic capacity. This improvement is likely to be due to an enhanced inotropic contractility, which only becomes apparent during exercise.

  • 6. Hannukainen, J
    et al.
    Kalliokosk, KK
    Nuutila, P
    Fujimoto, T
    Kemppainen, J
    Viljanen, T
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Parkkola, R
    Knuut, J
    Kjaer, M
    In Vivo Measurements of Glucose Uptake in Human Achilles Tendon During Different Exercise Intensities2005In: International Journal of Sports Medicine, ISSN 0172-4622, Vol. 26, p. 727-731Article in journal (Refereed)
    Abstract [en]

    Muscular contraction and loading of adjacent tendons has been demonstrated to cause increased blood flow and metabolic activity in the peritendinous region. However, it is poorly known to what extent the human tendon itself takes up glucose during exercise. Thus, the purpose of this study was to measure tendon glucose uptake with increasing exercise intensity and to compare it to muscle glucose uptake at the same intensities. Eight young men were examined on three separate days during which they performed 35 min of cycling at 30, 55 and 75 % of VO2max, respectively. Glucose uptake was measured directly by positron emission tomography (PET) with 2-[ (18)F]fluoro-2-deoxyglucose ([18F]FDG). [18F]FDG was injected after 10 min of exercise that was continued for a further 25 min after the injection. PET scanning of the thigh and Achilles region was performed after the exercise. Glucose uptake of the Achilles tendon (AT) remained unchanged (7.1 +/- 1.5, 6.6 +/- 1.1, and 6.0 +/- 1.1 micromol.kg(-1).min(-1)) with the increasing workload, although the glucose uptake in m. quadriceps femoris simultaneously clearly increased (48 +/- 35, 120 +/- 35, and 152 +/- 74 micromol.kg(-1).min(-1), p < 0.05). In conclusion, the AT takes up glucose during exercise but in significantly smaller amounts than the skeletal muscle does. Furthermore, glucose uptake in the AT is not increased with the increasing exercise intensity. This may be partly explained by the cycle ergometry exercise used in the present study, which probably causes only a little increase in strain to the AT with increasing exercise intensity.

  • 7.
    Ihalainen, Simo
    et al.
    KIHU - Research Institute for Olympic Sports, Jyväskylä, and Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kuitunen, Sami
    KIHU – Research Institute for Olympic Sports, Jyväskylä, Finland.
    Leppävuori, Antti
    Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, and Finnish Biathlon Association, Finland.
    Mikkola, Jussi
    KIHU – Research Institute for Olympic Sports, Jyväskylä, Finland.
    Lindinger, Stefan
    Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria.
    Linnamo, Vesa
    Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
    Technical determinants of biathlon standing shooting performance before and after race simulation2018In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 28, no 6, p. 1700-1707Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to identify performance determining factors in biathlon standing shooting in rest and after intense exercise. Eight Finnish national and nine junior team biathletes participated in the study. Participants fired 40 resting shots (REST) and 2*5 competition simulation shots (LOAD) after 5 min of roller skiing at 95% of peak heart rate. Hit percentage, aiming point trajectory and postural balance were measured from each shot. Cleanness of triggering (ATV, movement of the aiming point 0-0.2 s before the shot) and vertical stability of hold (DevY) were the most important components affecting shooting performance both in REST (DevY, R=-0.61, p<0.01; ATV, R=-0.65, p<0.01) and in LOAD (DevY, R=-0.50, p<0.05; ATV, R=-0.77, p<0.001). Postural balance, especially in shooting direction, was related to DevY and ATV. Stability of hold in horizontal (F(1,15)=7.025, p<0.05) and vertical (F(1,15)=21.285, p<0.001) directions, aiming accuracy (F(1,15)=9.060, p<0.01), and cleanness of triggering (F(1,15)=59.584, p<0.001) decreased from REST to LOAD, accompanied by a decrease in postural balance. National and junior team biathletes differed only in hit percentage in REST (92±8 % vs. 81±8 %, p<0.05) and left leg postural balance in shooting direction in LOAD (0.31±0.18 mm vs. 0.52±0.20 mm, p<0.05), and the intense exercise affected the shooting technical components similarly in both national and junior groups. Biathletes should focus on cleanness of triggering and vertical stability of hold in order to improve biathlon standing shooting performance. More stable postural balance in shooting direction could help to improve these shooting technical components.

  • 8.
    Jonsson, Malin
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Differences in range of motion and feet pressure between skiing with and without rifle in gear 3 for female biathletes2015In: Book of Abstracts of the 20th Annual Congress of theEuropean College of Sport Science – 24th - 27th June 2015, Malmö – Sweden / [ed] Radmann, A., Hedenborg, S., Tsolakidis, E., 2015Conference paper (Refereed)
  • 9. Kalliokoski,
    et al.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Takala,
    Knuuti,
    Nuutila,
    Muscle oxygen extraction and perfusion heterogeneity during continuous and intermittent static exercise2003In: Journal of Applied Physiology, ISSN 8750-7587, Vol. 94, p. 953-958Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to compare the effects of intermittent and continuous static exercise on muscle perfusion, perfusion heterogeneity, and oxygen extraction. Perfusion and oxygen uptake of quadriceps femoris muscle were measured in 10 healthy men by using positron emission tomography and [(15)O]H(2)O and [(15)O]O(2) first during intermittent static exercise [10% of maximal static force (MSF)] and thereafter during continuous static exercise at the same tension-time level (5% static; 5% of MSF). In 4 of these subjects, perfusion was measured during continuous static exercise with 10% of MSF (10% continuous) instead of the second [(15)O]O(2) measurement. Muscle oxygen consumption was similar during intermittent and 5% continuous, but muscle perfusion was significantly higher during 5% continuous. Consequently, muscle oxygen extraction fraction was lower during 5% continuous. Perfusion was also more heterogeneous during 5% continuous. When exercise intensity was doubled during continuous static exercise (from 5% continuous to 10% continuous), muscle perfusion increased markedly. These results suggest that continuous, low-intensity static exercise decreases muscle oxygen extraction and increases muscle perfusion and its heterogeneity compared with intermittent static exercise at the same relative exercise intensity.

  • 10. Kalliokoski, K K
    et al.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Knuuti, J
    Nuutila, P
    Perfusion distribution between and within muscles during intermittent static exercise in endurance-trained and untrained men2003In: International Journal of Sports Medicine, ISSN 0172-4622, Vol. 24, p. 400-403Article in journal (Refereed)
    Abstract [en]

    We have recently shown that muscle perfusion varies between different quadriceps femoris muscles during submaximal exercise in humans. In animals, endurance training changes perfusion distribution between muscles during exercise. Whether the same is observed in humans is currently unknown. Therefore, we compared perfusion levels between different parts of the quadriceps femoris muscle group during one-legged intermittent static exercise in seven endurance-trained and seven untrained men. Muscle perfusion was measured using positron emission tomography with [ 15O]-H 2 O. In addition, relative dispersion of perfusion (standard deviation within a region/mean within a region x 100 %) within each muscle region was calculated as an index of perfusion heterogeneity within the muscles. Muscle perfusion tended to be lower in endurance-trained men (p = 0.16) and it was also different between the regions (p < 0.001). However, perfusion distributed similarly between the groups (p = 0.51). Relative dispersion of perfusion within the muscles was lower in endurance-trained men (p = 0.01) and it was also different between muscles (p < 0.001). These results suggest that endurance training does not alter perfusion distribution between muscles, but it decreases perfusion heterogeneity within the muscles.

  • 11. Kalliokoski, K K
    et al.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Luotolahti, M
    Laine, H
    Takala, T O
    Nuutila, P
    Knuuti, J
    Myocardial perfusion and coronary resistance in cardiac fatigue after marathon running2002In: XXVII FIMS World Congress on Sports Medicine, 2002Conference paper (Refereed)
  • 12. Kalliokoski, K K
    et al.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Takala, T O
    Knuuti, J
    Nuutila, P
    Lihasten verenvirtaus, verenvirtauksen heterogeenisuus ja happiekstraktio vaiheittaisessa ja jatkuvassa staattisessa rasituksessa2002In: XI Liikunta-lääketieteen Päivät, 2002Conference paper (Refereed)
    Abstract [en]

    (in finnish only)

  • 13. Kalliokoski, K
    et al.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Knuuti, J
    Nuutila, P
    The effects of endurance training on muscle blood flow distribution between muscles in humans2001In: Book of Abstracts of the 6th Annual Congress of the European College of Sport Science in Cologne, Germany from 24-28 July 2001, 2001Conference paper (Refereed)
  • 14. Kalliokoski, K.K
    et al.
    Kuusela, T.A.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Knuuti, J
    Nuutila, P
    Muscle fractal vascular branching pattern and microvascular perfusion heterogeneity in endurance-trained and untrained men2003In: Journal of Physiology, ISSN 0022-3751, Vol. 546, no pt2, p. 529-35Article in journal (Refereed)
    Abstract [en]

    Less heterogeneous skeletal muscle perfusion has recently been reported in endurance-trained compared to untrained men at macrovascular level. The causes of this difference in perfusion heterogeneity are unknown as is whether the same difference is observed in microvasculature. We hypothesised that the difference could be caused by changes in muscle vascular branching pattern. Perfusion was measured in resting and exercising muscle in 14 endurance-trained and seven untrained men using [(15)O]water and positron emission tomography. Fractal dimension (D) of perfusion distribution was calculated as a measure of fractal characteristics of muscle vascular branching pattern. Perfusion heterogeneity in microvascular units (1 mm(3) samples) was estimated using the measured heterogeneity in voxels of positron emission tomography (PET) images (relative dispersion, RD = S.D./mean) and corresponding D values. D was similar between the groups (exercising muscle 1.11 +/- 0.07 and 1.14 +/- 0.06, resting muscle 1.12 +/- 0.06 and 1.14 +/- 0.03, trained and untrained, respectively). Trained men had lower perfusion (151 +/- 44 vs. 218 +/- 87 ml min(-1) kg(-1), P < 0.05) and macrovascular perfusion heterogeneity (relative dispersion 21 +/- 5 vs. 25 +/- 5 %, P < 0.05) in exercising muscle than untrained men. Furthermore, estimated perfusion heterogeneity in microvascular units in exercising muscle was also lower in trained men (33 +/- 7 vs.48 +/- 19 %, P < 0.05). These results show that fractal vascular branching pattern is similar in endurance-trained and untrained men but perfusion is less heterogeneous at both the macro- and the microvascular level in endurance-trained men. Thus, changes in fractal branching pattern do not explain the differences in perfusion heterogeneity between endurance-trained and untrained men.

  • 15. Kalliokoski, KK
    et al.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Luotolahti, M
    Laine, H
    Takala, TO
    Nuutila, P
    Knuuti,
    Knuuti, J
    Myocardial perfusion after marathon running2004In: Scandinavian Journal of Medicine and Science in Sport, ISSN 0905-7188, Vol. 14, no 4, p. 208-214Article in journal (Refereed)
    Abstract [en]

    We investigated the effects of acute prolonged exercise (marathon running) on cardiac function and myocardial perfusion. Cardiac dimensions and function were measured in seven endurance-trained men using echocardiography before and repeatedly after marathon (42.2 km) running (at 10 min, 150 min, and 20 h). Myocardial perfusion and perfusion resistance were measured using positron emission tomography and 15O-H2O before and 85-115 min after running. Echocardiographic indices showed only mild and clinically non-significant changes in cardiac function after running. Rate-pressure-corrected basal myocardial perfusion (0.89+/-0.13 vs. 1.20+/-0.32 mL min(-1) g(-1), P=0.04) was increased after running. Also, adenosine-stimulated perfusion tended to be higher (3.67+/-0.81 vs. 4.47+/-0.52 mL min(-1) g(-1), P=0.12) and perfusion resistance during adenosine stimulation was significantly lower after running (26+/-6 vs. 18+/-3 mmHg min g mL(-1), P=0.03). Plasma free fatty acid (FFA) concentration was significantly increased after running. These results show that marathon running does not cause marked changes in cardiac function in healthy men. Basal perfusion was increased after exercise, probably reflecting changes in fuel preferences to increased use of FFAs. Strenuous exercise also seems to enhance coronary reactivity, which could thereby serve as a protective mechanism to vascular events after exercise.

  • 16. Kalliokoski, K.K.
    et al.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Luotolahti, M.
    Laine, H.
    Takala, T.O.
    Nuutila, P.
    Knuuti, J.
    Myocardial blood flow and coronary resistance in 'myocardial fatigue' a cardiac dysfunction following prolonged exercise2001In: Proceedings of the 16th International Puijo Symposium, 2001Conference paper (Refereed)
  • 17. Kyröläinen, H
    et al.
    Linnamo, V
    Aveja, J
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kivelä, R
    Sipilä, S
    Selänne, H
    Komi, P V
    Neuromuscular responses to fatiguing stretch-shortening cycle exercise in different muscle actions2004In: Book of abstracts of the 4th International Conference on Strength Training, November 3-7, 2004 Serres, Greece, 2004, p. 306-307Conference paper (Refereed)
  • 18.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    The Acute Effects of Exercise on Skeletal Muscle Blood Flow: Positron Emission Tomography Studies in Healthy Subjects2005Doctoral thesis, comprehensive summary (Other academic)
  • 19.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Ainegren, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lisspers, Jan
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Effects of combined relaxation and shooting training on shooting performance in biathlon2009In: Effects of combined relaxation and shooting training on shooting performance in biathlon, 2009Conference paper (Refereed)
  • 20.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Ainegren, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lisspers, Jan
    Mid Sweden University, Faculty of Human Sciences, Department of Social Sciences.
    Evidence of improved shooting precision in biathlon after 10-weeks of combined relaxation and specific shooting training2011In: Cognitive Behaviour Therapy, ISSN 1650-6073, E-ISSN 1651-2316, Vol. 40, no 4, p. 237-250Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to test the hypothesis that a combined relaxation (applied tension release, ATR) and specific shooting training regimen may enhance shooting ability of biathlon athletes. Seven biathletes of high national level were randomized into an experimental group (age 20 ± 5 years; Vo 2max 60 ± 8 mL kg− 1 min− 1) and were asked to add this special training intervention to their regular training for 10 weeks, while five other biathletes served as controls (age 19 ± 2 years; Vo 2max 57 ± 10 mL kg− 1 min− 1). The shooting ability of the subjects was assessed before and after the intervention at rest and after roller skiing on a treadmill in a laboratory-based competition simulating assessment. After the intervention period, the experimental group demonstrated a significantly enhanced shooting performance compared to the control group. No changes in Vo 2max or in heart rate and Vo 2 responses were observed before and after the intervention in either group and there were no differences between the groups in these parameters. Thus, the preliminary conclusion is that a combination of ATR and specific shooting training seems to be instrumental in enhancing the shooting performance in biathlon.

  • 21.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Andersson, Erik
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Jonsson, Malin
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Laboratory-based factors predicting performance in biathlon skiing2017Conference paper (Refereed)
  • 22.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Heinonen, Ilkka
    Turku PET Centre, University of Turku, Finland.
    Kemppainen, Jukka
    Turku PET Centre, University of Turku, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Kyröläinen, Heikki
    University of Jyväskylä, Finland.
    Kalliokoski, Kari
    Turku PET Centre, University of Turku, Finland.
    Perfusion heterogeneity does not explain excess muscle oxygen uptake during variable intensity exercise2010In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 30, no 4, p. 241-249Article in journal (Refereed)
    Abstract [en]

    The association between muscle oxygen uptake (VO2) and perfusion or perfusion heterogeneity (relative dispersion, RD) was studied in eight healthy male subjects during intermittent isometric (1 s on, 2 s off) one-legged knee-extension exercise at variable intensities using positron emission tomography and a-v blood sampling. Resistance during the first 6 min of exercise was 50% of maximal isometric voluntary contraction force (MVC) (HI-1), followed by 6 min at 10% MVC (LOW) and finishing with 6 min at 50% MVC (HI-2). Muscle perfusion and O2 delivery during HI-1 (26 ± 5 and 5·4 ± 1·0 ml 100 g−1 min−1) and HI-2 (28 ± 4 and 5·8 ± 0·7 ml 100 g−1 min−1) were similar, but both were higher (P<0·01) than during LOW (15 ± 3 and 3·0 ± 0·6 ml 100 g−1 min−1). Muscle VO2 was also higher during both HI workloads (HI-1 3·3 ± 0·4 and HI-2 4·1 ± 0·6 ml 100 g−1 min−1) than LOW (1·4 ± 0·4 ml 100 g−1 min−1; P<0·01) and 25% higher during HI-2 than HI-1 (P<0·05). O2 extraction was higher during HI workloads (HI-1 62 ± 7 and HI-2 70 ± 7%) than LOW (45 ± 8%; P<0·01). O2 extraction tended to be higher (P = 0·08) during HI-2 when compared to HI-1. Perfusion was less heterogeneous (P<0·05) during HI workloads when compared to LOW with no difference between HI workloads. Thus, during one-legged knee-extension exercise at variable intensities, skeletal muscle perfusion and O2 delivery are unchanged between high-intensity workloads, whereas muscle VO2 is increased during the second high-intensity workload. Perfusion heterogeneity cannot explain this discrepancy between O2 delivery and uptake. We propose that the excess muscle VO2 during the second high-intensity workload is derived from working muscle cells.

  • 23.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pettersson, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Performance predicting factors during prolonged non-steady state cycling2006In: Book of Abstracts of the 11th Annual Congress of the European College of Sport Science in Lausanne, Switzerland from 5-8 July 2006, 2006Conference paper (Refereed)
  • 24.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Finkenzeller, Thomas
    University of Salzburg, Salzburg, Austria.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. UiT, The Arctic University of Norway, Tromsø, Norway.
    Sattlecker, Gerold
    University of Salzburg, Salzburg, Austria.
    The influence of physiobiomechanical parameters, technical aspects of shooting, and psychophysiological factors on biathlon performance: A review2018In: Journal of Sport and Health Science, ISSN 2095-2546, E-ISSN 2213-2961, Vol. 7, no 4, p. 394-404Article in journal (Refereed)
    Abstract [en]

    The biathlon, an Olympic sporting discipline that combines cross-country skiing with rifle marksmanship, entails considerable physiological demands, as well as fine motor control while shooting after intense exercise and under mental pressure. Although much of our knowledge about cross-country skiing is probably also applicable to the biathlon, carrying the rifle and shooting under stress make this discipline somewhat unique. The present review summarizes and examines the scientific literature related to biathlon performance, with a focus on physiological and biomechanical factors and shooting technique, as well as psychophysiological aspects of shooting performance. We conclude with suggestions for future research designed to extend our knowledge about the biathlon, which is presently quite limited.

  • 25.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Heinonen, Ilkka
    Turku PET Centre, University of Turku, Finland.
    Luotolahti, Matti
    University of Turku, Finland.
    Nuutila, Pirjo
    Turku PET Centre, University of Turku, Finland.
    Raitakari, Olli
    Turku PET Centre, University of Turku, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Kalliokoski, Kari
    Turku PET Centre, University of Turku, Finland.
    Left-ventricular hypertrophy associates to impaired maximal myocardial perfusion in endurance-trained men2009Conference paper (Refereed)
    Abstract [en]

    Long-term endurance training induces morphological adaptations in heart, such as left-ventricular (LV) hypertrophy caused by wall thickening and cavity enlargement. Interestingly, these anatomical changes in the heart are strikingly similar to certain pathophysiological changes (Pellicia 2000). Previous studies have shown that the perfusion response in myocardium during dipyridamole- or adenosine infusion is decreased in several pathophysiological states with LV hypertrophy (e.g. Stolen et al. 2004). However, studies in endurance athletes with LV hypertrophy have shown contradictory results on myocardial perfusion response ranging from reduced to increased myocardial perfusion during dipyridamole- or adenosine-induced vasodilation compared to untrained men (Kjaer et al. 2005; Kalliokoski et al. 2002). The degree of hypertrophy could explain the discrepant findings in studies in athletes, but it has not been thoroughly investigated. Thus, we examined totally 31 endurance athletes (ET) and 25 untrained (UT) men in order to study the association between myocardial functional and anatomical parameters measured with echocardiography, and myocardial perfusion (at rest and during maximal vasodilation induced by iv adenosine) measured with Positron Emission Tomography. Both VO2max (60+-5 vs 42+-8 ml/kg/min, p<0.001) and LVmass index (169+-27 vs 102+-15 g/m2, p<0.001) were markedly higher in ET. Resting myocardial perfusion was similar between the groups (ET 0.7+-0.2 vs UT 0.8+-0.2 ml/g/min, p=0.22) whereas adenosine-stimulated perfusion was lower in ET (2.9+-1.0 vs 3.7+-1.0 ml/g/min, p<0.01). VO2max correlated inversely with adenosine-stimulated perfusion in ET (r=-0.39, p=0.03) and with resting perfusion in UT (-0.49, p=0.01). Forward LV work correlated linearly with resting perfusion in both groups (ET r=0.54, p<0.01; UT r=0.50, p=0.01). ET group was further divided into three subgroups according to LVmass index (ET1: LVmass index <150g/m2, n=9; ET2 LVmass index 150-180 g/m2, n=12; ET3 LVmass index >180 gm2, n=10). Adenosine-induced myocardial perfusion decreased gradually when LVmass increased (UT 3.7+-1.+0 vs ET1 3.3+-0.9 vs ET2 2.7+-1.4 vs ET3 2.6+-0.5 mL g-1 min-1, p=0.008). LVmass index was also inversely related to adenosine-induced perfusion in entire study population (r=-0.46, p<0.01). Therefore, these results suggest that endurance training-induced severe cardiac hypertrophy impairs myocardial perfusion capacity.

    Kalliokoski K et al. (2002) Med Sci Sports Exerc 34:948-53

    Kjaer A et al. (2005) Am J Cardiol 96:1692-98

    Pellicia A (2000) Curr Cardiol Rep 2(2):166-71

    Stolen KQ et al (2004) 10(2):132-40

  • 26.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Jonsson, Malin
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. UiT The Arctic University of Norway, Tromsø, Norway; The University of British Columbia, Vancouver, BC, Canada.
    The Olympic biathlon – Recent advances and perspectives after Pyeongchang2018In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, no JUL, article id 796Article in journal (Refereed)
    Abstract [en]

    The biathlon, combining cross-country ski skating with rifle marksmanship, has been an Olympic event since the Winter Games in Squaw Valley, United States, in 1960. As a consequence of replacing the classical with the skating technique in the 1980s, as well as considerable improvements in equipment and preparation of ski tracks and more effective training, the average biathlon skiing speed has increased substantially. Moreover, the mass-start, pursuit, and sprint races have been introduced. Indeed, two of the four current individual Olympic biathlon competitions involve mass-starts, where tactics play a major role and the outcome is often decided during the last round of shooting or final sprint. Biathlon is a demanding endurance sport requiring extensive aerobic capacity. The wide range of speeds and slopes involved requires biathletes to alternate continuously between and adapt different skating sub-techniques duringraces, a technical complexity that places a premium on efficiency. Although the relative amounts of endurance training at different levels of intensity have remained essentially constant during recent decades, today’s biathletes perform more specific endurance training on roller skis on terrain similar to that used for competition, with more focus on the upper-body, systematic strength and power training and skiing at higher speeds. Success in the biathlon also requires accurate and rapid shooting while simultaneously recovering from high-intensity skiing. Many different factors, including body sway, triggering behavior, and even psychology, influence the shooting performance. Thus, the complexity of biathlon deserves a greater research focus on areas such as race tactics, skating techniques, or shooting process.

  • 27.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kallikoski, K. K.
    Luotolahti, M.
    Kemppainen, J.
    Teräs, M.
    Kyröläinen, H.
    Nuutila, P.
    Knuuti, J.
    Myocardial perfusion during exercise in endurance-trained and untrained humans2007In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 293, no 2, p. R837-R843Article in journal (Refereed)
  • 28.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kalliokoski,
    Kyröläinen,
    Kemppainen,
    Teräs,
    Sipilä,
    Nuutila,
    Knuuti,
    Skeletal muscle blood flow and flow heterogeneity during dynamic and isometric exercise in humans2003In: American Journal of Physiology: Heart and Circulatory Physiology, ISSN 0363-6135, Vol. 284, p. 979-986Article in journal (Refereed)
    Abstract [en]

    The effects of dynamic and intermittent isometric knee extension exercises on skeletal muscle blood flow and flow heterogeneity were studied in seven healthy endurance-trained men. Regional muscle blood flow was measured using positron emission tomography (PET) and an [(15)O]H(2)O tracer, and electromyographic (EMG) activity was recorded in the quadriceps femoris (QF) muscle during submaximal intermittent isometric and dynamic exercises. QF blood flow was 61% (P = 0.002) higher during dynamic exercise. Interestingly, flow heterogeneity was 13% (P = 0.024) lower during dynamic compared with intermittent isometric exercise. EMG activity was significantly higher (P < 0.001) during dynamic exercise, and the change in EMG activity from isometric to dynamic exercise was tightly related to the change in blood flow in the vastus lateralis muscle (r = 0.98, P < 0.001) but not in the rectus femoris muscle (r = -0.09, P = 0.942). In conclusion, dynamic exercise causes higher and less heterogeneous blood flow than intermittent isometric exercise at the same exercise intensity. These responses are, at least partly, related to the increased EMG activity.

  • 29.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kalliokoski, K. K.
    Luotolahti, M.
    Takala, T.
    Nuutila, O. P.
    Knuuti, J.
    Sydämen verenvirtaus ja koronaariresistanssi maraton juoksun jälkeen2002In: Liikunta & Tiede, ISSN 0358-7010, Vol. 5Article in journal (Other (popular scientific, debate etc.))
  • 30.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kalliokoski, K. K.
    Luotolahti, M.
    Takala, T. O.
    Nuutila, P.
    Knuuti, J.
    Effects of Marathon Running on Myocardial Blood Flow and Coronary Resistance.2001In: Book of Abstracts of the 6th Annual Congress of the European College of Sport Science in Cologne, Germany from 24-28 July 2001, 2001Conference paper (Refereed)
  • 31.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kalliokoski, K.
    Kemppainen, J.
    Teräs, M.
    Kyröläinen, H.
    Knuuti, J.
    The effects of exercise on myocardial blood flow in trained and untrained subjects in vivo studies using PET2003In: Book of Abstracts of the 8th Annual Congress of the European College of Sport Science in Salzburg, Austria from 9-12 July 2003, 2003Conference paper (Refereed)
  • 32.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kalliokoski, K.
    Luotolahti, M.
    Takala, T. O.
    Nuutila, P.
    Knuuti, J.
    Myocardial blood flow and coronary resistance in myocardial fatigue, a cardiac dysfunction following prolonged exercise2002In: European Heart Journal, 2002, Vol. 22, no Supplement, p. 46-46Conference paper (Refereed)
  • 33.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kalliokoski, Kari
    Turku PET Centre, University of Turku, Finland.
    Kemppainen, Jukka
    Turku PET Centre, University of Turku, Finland.
    Takala, Timo
    Neuromuscular Research Centre, University of Jyväskylä, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Nuutila, Pirjo
    Turku PET Centre, University of Turku, Finland.
    Kyröläinen, Heikki
    Neuromuscular Research Centre, University of Jyväskylä, Finland.
    ASSOCIATION BETWEEN MECHANICAL EFFICIENCY AND MUSCLE METABOLISM DURING LEG EXERCISE2011Conference paper (Refereed)
  • 34.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kemppainen, J.
    Turku PET Centre, University of Turku, Turku, Finland .
    Kyrolainen, H.
    Department of Biology of Physical Activity, Neuromuscular Research Centre, University of Jyväskylä, Jyväskylä, Finland .
    Knuuti, J.
    Turku PET Centre, University of Turku, Turku, Finland .
    Nuutila, P.
    Turku PET Centre, University of Turku, Turku, Finland .
    Kalliokoski, K. K.
    Turku PET Centre, University of Turku, Turku, Finland .
    Regional differences in blood flow, glucose uptake and fatty acid uptake within quadriceps femoris muscle during dynamic knee-extension exercise2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 7, p. 1775-1782Article in journal (Refereed)
    Abstract [en]

    The purpose of the present study was to investigate the regional differences in glucose and fatty acid uptake within skeletal muscle during exercise. Blood flow (BF), glucose uptake (GU) and free fatty acid uptake (FFAU) were measured in four different regions (vastus lateralis, VL; rectus femoris, RF; vastus intermedius, VI; and vastus medialis, VM) of the quadriceps femoris (QF) muscle during low-intensity, knee-extension exercise using positron emission tomography. BF was higher in VI than in VL, RF and VM (P < 0.05). FFAU was higher in VI (P < 0.001) but also in VM (P < 0.05) compared with VL and RF. In contrast, GU was higher in RF compared with VL (P < 0.05) but was not significantly different to VM or VI (both P = NS). FFAU within these four muscle regions correlated significantly with BF (r = 0.951, P < 0.05), whereas no significant relationship was observed between GU and BF (r = 0.352, P = NS). Therefore, skeletal muscle FFAU, but not GU, appears to be associated with BF during low-intensity exercise. The present results also indicate considerable regional differences in substrate use within working QF muscle. As such, an important methodological outcome from these results is that one sample from a specific part of the QF muscle does not represent the response in the entire QF muscle group.

  • 35.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kemppainen, Jukka
    Turku PET Centre, University of Turku, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Nuutila, Pirjo
    Turku PET Centre, University of Turku, Finland.
    Kalliokoski, Kari
    Turku PET Centre, University of Turku, Finland.
    REGIONAL DIFFERENCES IN BLOOD FLOW, GLUCOSE UPTAKE, AND FATTY-ACID UPTAKE WITHIN QUADRICEPS FEMORIS MUSCLE GROUP DURING DYNAMIC KNEE-EXTENSION EXERCISE2011Conference paper (Refereed)
  • 36.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kivelä, R.
    University of Jyväskylä, Jyväskylä, Finland.
    Kyröläinen, H.
    University of Jyväskylä, Jyväskylä, Finland.
    Sipilä, S.
    University of Jyväskylä, Jyväskylä, Finland.
    Selänne, H.
    University of Jyväskylä, Jyväskylä, Finland.
    Lautamäki, R.
    University of Turku, Turku, Finland.
    Nuutila, P.
    University of Turku, Turku, Finland.
    Knuuti, J.
    University of Turku, Turku, Finland.
    Kalliokoski, K.K.
    University of Turku, Turku, Finland.
    Komi, P. V.
    University of Jyväskylä, Jyväskylä, Finland.
    Effects of exhaustive stretch-shortening cycle exercise on muscle blood flow during exercise2006In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 186, no 4, p. 261-270Article in journal (Refereed)
    Abstract [en]

    Abstract Aim: The influence of exhaustive stretch-shortening cycle exercise (SSC) on skeletal muscle blood flow (BF) during exercise is currently unknown. Methods: Quadriceps femoris (QF) BF was measured in eight healthy men using positron emission tomography before and 3 days after exhaustive SSC exercise. The SSC protocol consisted of maximal and submaximal drop jumps with one leg. Needle biopsies of the vastus lateralis muscles were taken immediately and 2 days after SSC for muscle endothelial nitric oxide synthase (eNOS) and interleukin-1-beta (IL-1beta) mRNA level determinations. Results: All subjects reported subjective muscle soreness after SSC (P < 0.001), which was well in line with a decrease in maximal isometric contraction force (MVC) and increase in serum creatine kinase activity (CK) (P = 0.018). After SSC muscle BF was 25% higher in entire QF (P = 0.043) and in its deep and superficial muscle regions, whereas oxygen uptake remained unchanged (P = 0.893). Muscle biopsies revealed increased IL-1beta (30 min: 152 +/- 75%, P = 0.012 and 2 days: 108 +/- 203%, P = 0.036) but decreased or unchanged eNOS (30 min; -21 +/- 57%, P = 0.050 and 2 days: +101 +/- 204%, P = 0.779) mRNA levels after SSC. Conclusion: It was concluded that fatiguing SSC exercise induces increased muscle BF during exercise, which is likely to be associated with pro-inflammatory processes in the exercised muscle.

  • 37.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kyrölainen, H
    Kemppainen, J
    Teräs, M
    Sipilä, H
    Nuutila, P
    Knuuti, J
    Kalliokoski, K K
    Dynamic exercise causes higher skeletal muscle perfusion than intermittent isometric exercise2002In: IX Turku PET Symposium, 2002Conference paper (Other scientific)
  • 38.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kyrölainen, H
    Kivelä, R
    Sipilä, S
    Selänne, H
    Lautamäki, R
    Nuutila, P
    Knuuti, J
    Komi, P V
    Exercise induced muscle damage increases skeletal muscle blood flow during dynamic exercise2004In: 9th Annual Congress of the European College of Sport Sciences, 2004Conference paper (Other scientific)
  • 39.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Turku PET Centre, University of Turku, Turku, Finland.
    Kyröläinen, H.
    Neuromuscular Research Centre, University of Jyväskylä, Jyväskylä, Finland.
    Kalliokoski, K.K.
    Turku PET Centre, University of Turku, Turku, Finland.
    Nuutila, P.
    Department of Medicine, University of Turku, Turku, Finland; Turku PET Centre, University of Turku, Turku, Finland .
    Knuuti, J.
    Turku PET Centre, University of Turku, Turku, Finland; .
    The association between muscle EMG and perfusion in knee extensor muscles2006In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 26, no 2, p. 99-105Article in journal (Refereed)
    Abstract [en]

    The relationships between electromyographic (EMG) activity and force as well as muscle blood flow and work have been well established. However, the association between muscle blood flow and EMG activity remains unsolved. Thus, to test the hypothesis that muscle EMG activity relates to muscle perfusion in different compartments of the quadriceps femoris (QF) muscle, 12 healthy male subjects were studied. During two very submaximal exercise bouts, at different exercise intensities, oxygen labelled radiowater and positron emission tomography were used to measure muscle perfusion. In addition, produced force of knee extensors and muscle EMG activity in the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles were recorded during both exercise bouts. Although the exercise intensity and average force production was higher during the second exercise bout (3815 vs. 5117 N; p=0.007), the mean EMG activity was lower (RF; p<0.001) or unchanged (VL; p=0.722 and VM; p=0.640). During the second exercise period, perfusion also remained unchanged in the entire QF muscle (p=0.223) and in its separate muscles (VL, p=0.703; VM, p=0.141; RF, p=0.113) in a group level. However, the individual changes in muscle perfusion were tightly related to changes in muscle EMG activity in VL (r=0.84; p=0.002) and in VM (r=0.68; p=0.015) but poorly in the RF muscle (r=0.40; p=0.257). In conclusion, the different associations between muscle perfusion and EMG activity in different QF muscles suggests specific functional role of the vasti muscles and the RF muscle.

  • 40.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kyröläinen, H.
    Kemppainen, J.
    Teräs, M.
    Sipilä, H.
    Nuutila, P.
    Knuuti, P.
    Kalliokoski, K K
    Dynamic exercise causes higher skeletal muscle perfusion than intermittent isometric exercise2002In: Book of Abstracts of the 7th Annual Congress of the European College of Sport Science in Athens, Greece from 24-28 July 2002, 2002Conference paper (Refereed)
  • 41.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Kyröläinen, Heikki
    University of Jyväskylä, Finland.
    Kemppainen, Jukka
    University of Turku, Finland.
    Knuuti, Juhani
    University of Turku, Finland.
    Kalliokoski, Kari
    University of Turku, Finland.
    Muscle free fatty-acid uptake associates to mechanical efficiency during exercise in humans2018In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, no AUG, article id 1171Article in journal (Refereed)
    Abstract [en]

    Intrinsic factors related to muscle metabolism may explain the differences in mechanical efficiency (ME) during exercise. Therefore, this study aimed to investigate the relationship between muscle metabolism and ME. Totally 17 healthy recreationally active male subjects were recruited and divided into efficient (EF; n=8) and inefficient (IE; n=9) groups, which were matched for age (mean±SD 24±2 vs. 23±2 yrs), BMI (23±1 vs. 23±2 kg m-2), physical acitivity levels (3.4±1.0 vs. 4.1±1.0 sessions/week), and V ̇O2peak (53±3 vs. 52±3 mL kg-1 min-1), respectively, but differed for ME at 45% of VO2peak intensity during submaximal bicycle ergometer test (EF 20.5±3.5 vs. IE 15.4±0.8 %, P < 0.001). Using Positron Emission Tomography, muscle blood flow (BF) and uptakes of oxygen (mVO2), fatty acids (FAU) and glucose (GU) were measured during dynamic submaximal knee-extension exercise. Workload-normalized BF (EF 35±14 vs. IE 34±11 mL 100g-1 min-1, P = 0.896), mVO2 (EF 4.1±1.2 vs. IE 3.9±1.2 mL 100g-1 min-1, P = 0.808), and GU (EF 3.1±1.8 vs. IE 2.6±2.3 μmol 100g-1 min-1, P = 0.641) as well as the delivery of oxygen, glucose, and fatty acids, as well as respiratory quotient were not different between the groups. However, FAU was significantly higher in EF than IE (3.1±1.7 vs. 1.7±0.6 μmol 100g-1 min-1, P < 0.047) and it also correlated with ME (r=0.56, P < 0.024) in the entire study group. EF group also demonstrated higher use of plasma fatty acids than IE, but no differences in use of plasma glucose and intramuscular energy sources were observed between the groups. These findings suggest that the effective use of plasma fatty acids is an important determinant of mechanical efficiency during exercise.

  • 42.
    Laaksonen, Marko S
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Heinonen, Ilkka
    Turku PET Centre, University of Turku, Finland.
    Kemppainen, Jukka
    Turku PET Centre, University of Turku, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Kyrölainen, Heikki
    Neuromuscular Research Centre, University of Jyväskylä, Finland.
    Kalliokoski, Kari K
    Turku PET Centre, University of Turku, Finland.
    Effects of intensity variation and muscle fatigue during knee-extension exercise on muscle perfusion and oxygen uptake2008In: Book of Abstracts of the 11th Annual Congress of the European College of Sport Science in Estoril, Portugal, from 9-12 July 2008, 2008Conference paper (Other scientific)
  • 43.
    Laaksonen, Marko S
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Heinonen, Ilkka
    Turku PET Centre, Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Finland.
    Luotolahti, Matti
    Department of Clinical Physiology and Nuclear Medicine, University of Turku, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Kalliokoski, Kari K
    Turku PET Centre, University of Turku, Finland.
    VO2peak, myocardial hypertrophy, and myocardial blood flow in endurance-trained men2014In: Medicine and science in sports and exercise, ISSN 1530-0315, Vol. 46, no 8, p. 1498-1505Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: Endurance training induces cardiovascular and metabolic adaptations, leading to enhanced endurance capacity and exercise performance. Previous human studies have shown contradictory results in functional myocardial vascular adaptations to exercise training, and we hypothesized that this may be related to different degrees of hypertrophy in the trained heart. METHODS: We studied the interrelationships between peak aerobic power (V̇O2peak), myocardial blood flow (MBF) at rest and during adenosine-induced vasodilation, and parameters of myocardial hypertrophy in endurance-trained (ET, n = 31) and untrained (n = 17) subjects. MBF and myocardial hypertrophy were studied using positron emission tomography and echocardiography, respectively. RESULTS: Both V̇O2peak (P < 0.001) and left ventricular (LV) mass index (P < 0.001) were higher in the ET group. Basal MBF was similar between the groups. MBF during adenosine was significantly lower in the ET group (2.88 ± 1.01 vs 3.64 ± 1.11 mLg-1min-1, P < 0.05) but not when the difference in LV mass was taken into account. V̇O2peak correlated negatively with adenosine-stimulated MBF, but when LV mass was taken into account as a partial correlate, this correlation disappeared. CONCLUSIONS: The present results show that increased LV mass in ET subjects explains the reduced hyperemic myocardial perfusion in this subject population and suggests that excessive LV hypertrophy has negative effect on cardiac blood flow capacity.

  • 44.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Takala, T. O.
    Knuuti, J.
    Nuutila, P.
    Kalliokoski, K. K.
    Muscle perfusion and oxygen extraction durign two isometric exercise modes studied using PET2002In: Abstracts of the IX Turku PET Symposium, 2002Conference paper (Refereed)
  • 45.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Takala, T. O.
    Knuuti, J.
    Nuutila, P.
    Kalliokoski, K. K.
    Muscle perfusion and oxygen extraction during two isometric exercise modes studied using PET2002In: Book of Abstracts of the 7th Annual Congress of the European College of Sport Science in Athens, Greece from 24-28 July 2002, 2002Conference paper (Refereed)
  • 46.
    Lund Ohlsson, Marie
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Höök, M.
    Laaksonen, Marko S.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    On the effect of sitting position, in simulated cross-country sit-skiing2016Conference paper (Refereed)
    Abstract [en]

    Introduction

    In Cross-country sit-skiing (CCSS), athletes with severe reduced trunk control are mainly seated with the knees higher than the hip (KH; arm and trunk powered). However this posture is hypothesized to have high risk for lower back and shoulder injuries. Therefore, a new seat was created where the knees were lower than hip and the trunk frontal supported (KL), to improve spinal curvature. Thus, the aim of this study was to examine performance between these two different sitting positions.

    Methods

    10 female abled-bodied elite cross-country skiers (age 25.5 ± 3.8 years (mean ± standard deviation), height 1.65 ± 0.05 m and weight 61.1 ± 6.8 kg) were tested on a skiing ergometer (ThoraxTrainer, ThoraxTrainer A/S, Kokkedal, Denmark) in a 30 s all-out test (WIN), a submaximal incremental test with 3-6 levels of 3 min (SUB), and a maximal 3 min time-trial test (MAX). The SUB and MAX tests were monitored breath-by-breath with a stationary metabolimeter (Quark CPET, COSMED, Italy). Aerobic metabolism and gross efficiency were computed from oxygen uptake, and anaerobic metabolism were estimated from net blood lactate concentrations. Muscle oxygenation saturation (SmO2) in right vastus lateralis (VL) was monitored with NIRS methodology (Moxy Monitor, Fortiori Design LLC, Minnesota, USA).

    Results

    Higher performance (W·kg-1) was observed for KH both in WIN (KL: 1.13 ± 0.33, KH: 1.40 ± 0.30) and MAX (KL: 0.67 ± 0.14, KH: 0.88 ± 0.19) compared to KL (p < 0.01). No differences were observed in breathing rate, cycle rate, oxygen consumption or aerobic metabolic rate neither in SUB nor MAX. The KH position showed higher gross efficiency and lower anaerobic metabolic rate and minute ventilation. SmO2 was higher for KH compared to baseline bench (12.2 ± 7.2%) whereas no difference was observed between baseline and KL position (3.2 ± 5.5%). During SUB levels 1-4, higher SmO2 was observed for KH compared to KL when normalizing data with baseline bench (p < 0.05).

    Discussion

    This study showed that abled bodied athletes perform better and have higher efficiency in KH compared to KL. The position using larger part of the body (joint range of motion and amount of active muscle mass) have higher gross efficiency, lower lactate concentration and lower ventilation, also shown by Lajunen (2014). It was also concluded that SmO2 was higher in KH compared to KL, and thus there might be a smaller risk for injuries in the legs connected to circulation. This study of abled-bodied athletes have the potential to serve as a control for future studies of para-athletes. 

    References

    Lajunen K (2014). Effect of sitting posture on sit-skiing economy. Bachelor’s thesis, University of Jyväskylä.

  • 47.
    Lund Ohlsson, Marie
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Sitting position affects performance in cross-country sit-skiing2017In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 117, no 6, p. 1095-1106Article in journal (Refereed)
    Abstract [en]

    Purpose: In cross-country sit-skiing (XCSS), athletes with reduced trunk control predominantly sit with the knees higher than the hips (KH); a position often associated with large spinal flexion. Therefore, to improve spinal curvature a new sledge with frontal trunk support, where knees are lower than hips (KL) was created. It was hypothesized that the KL position would improve respiratory function and enhance performance in seated double-poling compared to KH.

    Methods: Ten female able-bodied cross-country skiers (age 25.5 ± 3.8 years, height 1.65 ± 0.05 m, mass 61.1 ± 6.8 kg) completed a 30 s all-out test (WIN), a submaximal incremental test including 3–7 3 min loads (SUB) and a maximal 3 min time trial (MAX) in both KL and KH positions. During SUB and MAX external power, pole forces, surface electromyography, and kinematics were measured. Metabolic rates were calculated from oxygen consumption and blood lactate concentrations.

    Results: KL reduced spinal flexion and range of motion at the hip joint and indicated more muscle activation in the triceps. Performance (W kg−1) was impeded in both WIN (KH 1.40 ± 0.30 vs. KL 1.13 ± 0.33, p < 0.01) and MAX (KH 0.88 ± 0.19 vs. KL 0.67 ± 0.14, p < 0.01). KH resulted in higher gross efficiency (GE) and lower lactate concentration, anaerobic metabolic rate, and minute ventilation for equal power output.

    Conclusions: The new KL position can be recommended due to improved respiratory function but may impede performance. Generalization of results to XCSS athletes with reduced trunk muscle control may be limited, but these results can serve as a control for future studies of para-athletes.

  • 48.
    Lund Ohlsson, Marie
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Laaksonen, Marko S.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, L. Joakim
    Linköpings Universitet.
    Evaulation of two sitting positions in Cross-Country Sit-Skiing2016In: ICSS 2016 - International Congress on Science and Skiing, Arlberg, Austria, 10-15th December., 2016Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION

    In cross-country sit-skiing (CCSS) athletes with reduced trunk control mainly sit with their knees higher than the hips (KH) to increase trunk stability. To improve the spine curvature by reducing kyphosis a new sitting position was created where the knees are lower than the hips by help of a forward trunk support (KL). The aim of this study was to evaluate the new KL position and compare it to KH in terms of physiological and biomechanical measurements as well as musculoskeletal simulations.

    METHODS

    Five abled-bodied female cross-country skiers (62.6±8.1kg, 1.67±0.05m) performed two sets of tests; one in each sitting position on a skiing ergometer (ThoraxTrainer A/S, Denmark). Each test comprised a 30s all-out test (AO), an incremental submaximal test (4 to 6 x 3 min, SUB1-SUB6) and a maximal time-trial test of 3 min (MAX). During SUB and MAX external power and kinematics were measured. Metabolic rates (MR) were calculated from oxygen consumption and lactate concentrations.

    The AnyBody Modelling system (AMS 6.0, Anybody Technology A/S, Denmark) were used to simulate full-body musculoskeletal models over 4 poling cycles of SUB2, SUB4 and MAX. From the simulations muscular metabolic rate (mMR) and musculo-skeletal efficiency (ME) were computed (Holmberg et al., 2013).

    RESULTS & DISCUSSION

    The performance (W/kg) was higher in KH (p < 0.01) in both AO (24%) and MAX (32%). KL had more flexed knee, more extended hip and less kyphosis in trunk, while KH had larger range of motion (ROM) in hip and larger flexion and ROM in spine at SUB4 and MAX. Gross efficiency (GE) was higher in KH than KL. The total MR and ratio of anaerobic MR to total MR were higher in KL at SUB3 and SUB4.

    Simulations showed that 4 subjects had higher ME in KH for both SUB4 and MAX, though no statistical significance were observed. mMR were higher for KL at SUB2 and SUB4 but it was higher for KH at MAX. The ratio of mMR in body parts to total mMR showed higher ratio for KL in arm-shoulders (6.7-9.1%) and higher ratio for KH in trunk (3.7-4.6%) and hip-legs (3.0-4.6%).

    CONCLUSION

    The physiological results were comparable to others (Lajunen, 2014 & Verellen et al, 2012) and the simulation results were novel by showing how the motion of the trunk contributes to the total metabolic rate. KH position showed higher performance and GE while the KL position indicated higher mMR for arm-shoulders, and had also higher anaerobic MR. Therefore the KH position is favorable for abled-bodied athletes because KL limits trunk motion.

    REFERENCES

    Holmberg, L. J. et al. (2013). Comput Methods Biomech Biomed Engin16(9), 987-992. Lajunen, K. (2014). Effect of sitting posture on sit-skiing economy. Bachelor’s thesis, University of Jyväskylä.Verellen, J. et al. (2012). Eur J Appl Physiol, 112(3), 983-989.

  • 49.
    Mikkola, Jussi
    et al.
    University of Jyväskylä.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Linnamo, Vesa
    University of Jyväskylä.
    Changes in double poling forces and cycle characteristics during cross-country skiing sprint competition2010In: Proceedings for the fifth international conference on Science and Skiing, Salzburg: Meyer & Meyer Sport, 2010Conference paper (Refereed)
  • 50.
    Mikkola, Jussi
    et al.
    Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Nummela, Ari
    Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland.
    Linnamo, Vesa
    Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland.
    Changes in performance and poling kinetics during cross-country sprint skiing competition using the double-poling technique2013In: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 12, no 4, p. 355-364Article in journal (Refereed)
    Abstract [en]

    In this study, changes in skiing performance and poling kinetics during a simulated cross-country sprint skiing competition were investigated. Twelve elite male cross-country skiers performed simulated sprint competition (4 × 1,150 m heat with 20 min recovery between the heats) using the double-poling technique. Vertical and horizontal pole forces and cycle characteristics were measured using a force plate system (20-m long) during the starting spurt, racing speed, and finishing spurt of each heat. Moreover, heat and 20-m phase velocities were determined. Vertical and horizontal pole impulses as well as mean cycle length were calculated. The velocities of heats decreased by 2.7 ± 1.7% (p = 0.003) over the simulated competition. The 20-m spurting velocity decreased by 16 ± 5% (p < 0.002) and poling time increased by 18 ± 9% (p < 0.003) in spurt phases within heats. Vertical and horizontal poling impulses did not change significantly during the simulation; however, the mean forces decreased (p < 0.039) (vertical by 24 ± 11% and horizontal by 20 ± 10%) within heats but not between the heats. Decreased heat velocities over the simulated sprint and spurting velocities within heats indicated fatigue among the skiers. Fatigue was also manifested by decreased pole force production and increased poling time.

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