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  • 51.
    Nilsson, Johnny E
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Rosdahl, Hans G
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    New Devices for Measuring Forces on the Kayak Foot-Bar and on the Seat During Flat-Water Kayak Paddling: a technical report.2014Inngår i: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 9, nr 2, s. 365-70Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose was to develop and validate portable force-measurement devices for recordings of push and pull forces applied by each foot to the foot-bar of a kayak, and the horizontal force at the seat. A foot-plate on a single-point force transducer mounted on the kayak foot-bar underneath each foot allowed the push and pull forces to be recorded. Two metal frames interconnected with four linear ball-bearings and a force transducer allowed recording of horizontal seat force. The foot-bar force device was calibrated by loading each foot plate with weights in the push pull direction perpendicular to the foot plate surface while the seat force device was calibrated to horizontal forces with and without weights on the seat. A strong linearity (r2=0.99-1.0) was found between transducer output signal and load force in the push and pull directions for both foot-bar transducers perpendicular to the foot plate and the seat-force measuring device. Reliability of both devices was tested by means of a test-retest design. The coefficient of variation (CV) for foot-bar push and pull forces ranged from 0.1 to 1.1% and the CV for the seat forces varied between 0.6 - 2.2%. The present study opens up for new investigations of the forces generated within the kayak and ways to optimize kayak paddling performance.

  • 52.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Fredriksson, Mårten
    Högskolan Dalarna.
    Peak Oxygen Uptake And Muscle Power Can Be Simultaneously Improved With Hybrid Training2015Inngår i: LASE Journal of Sport Science, ISSN 1691-9912, Vol. 6, nr 1, s. 3-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose was to investigate the effects of simultaneous endurance and strength training repeatedly performed in the same training sessions (hybrid training). Twenty-six habitually active female physical-education students took part in the study. They were assigned to a hybrid training group (HT) or one of two control groups (CON1; only endurance training and CON2; maintained their normal training regimen). In a pre- and post-test training design all the subjects were tested before and after the intervention period concerning peak oxygen uptake while pedalling on a cycle ergometer and power output in a progressive cycle ergometer pedalling power/strength test. The HT intervention group and the CON1 group trained three times per week for five weeks, while the CON2 group did not change their normal training regimen. The HT group used a pre-programmed cycle ergometer to pedal at a mean oxygen uptake of 70-75% VO2peak for 30 minutes, but the training time was divided into 60 intermittent work periods (6 seconds) at a very high relative intensity (approximately 190 % of VO2peak) interspersed with low-intensity work periods (24 seconds) at about 45% of VO2peak. The CON1 group trained at the same mean oxygen uptake level as the HT group but during 30 minutes continuous training. The HT group significantly increased VO2peak and muscle power performance. The CON1 group increased VO2peak significantly but not power/strength. The CON2 group did not change significantly in the parameters studied. Thus, it can be concluded that in-session hybrid training allows simultaneous significant improvements of both VO2peak and muscle power performance during cycle ergometer pedalling.

  • 53.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Dalarna university.
    Gürsoy, Adam
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Hermanson, Anders
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    DEVELOPMENT OF NONVISUAL SENSORY SKILL IN FOOTBALL2018Inngår i: LASE Journal of Sport Science, ISSN 1691-7669, Vol. 9, nr 2, s. 3-16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose was to study if young football players can develop theirnonvisual sensory performance, here defined as control of the ball withoutvisual feedback. In total 20 elite male football players participated in thestudy. Their mean age (±SD) was 12.1 (±0.5) years. The participants weredivided into an intervention group (n=12) and a control group (n=8). Theselection of players was based on performance in the non-visual slalom pretest. The study followed a pre- post-test design in which the interventiongroup practiced ball control without visual feedback (nonvisual sensorytraining) three times 30 minutes per week over four weeks as part of theirnormal training. The control group exercised conventional football trainingwith full vision for the same amount of time. The pre- and post-test consistedof two sub-tests performed with and without visual control: 1) a stationaryball control test and 2) a slalom course ball drive test. The results show asignificant improvement in the intervention group in both the stationary ballcontrol test (p<0.001 and Effect Size (ES)=1.59) and in the slalom balldrive test (p<0.004 and ES=1.09). The control group showed no significantchanges in performance between the pre- and post-test.

    Conclusion. Nonvisual sensory skill can be significantly improved in12 training sessions of 30 minutes each in young elite male football players.

  • 54.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Haugen, Per
    Knee angular displacement and extensor muscle activity in telemark skiing and in ski-specific strength exercises.2004Inngår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 22, nr 4, s. 357-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 55.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Jakobsen, Vidar
    Tveit, Per
    Eikrehagen, Olav
    Pole length and ground reaction forces during maximal double poling in skiing.2003Inngår i: Sports biomechanics / International Society of Biomechanics in Sports, ISSN 1476-3141, Vol. 2, nr 2, s. 227-36Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the investigation was to study the relationship between thrust phase duration, ground reaction force, velocity increase after pole thrust and pole angles versus pole length during double poling in roller skiing. Seven male regional elite cross-country skiers volunteered as subjects for the study. The subjects performed a maximal double pole thrust on roller skis with each of the three different pole lengths: 'short', self-selected (normal) and 'long'. The short and long poles were 7.5 cm shorter and 7.5 cm longer than the self-selected pole length. The subjects made seven maximal pole thrusts with each pole length, which were randomly selected during 21 trials. For each trial the subjects accelerated from a 1.2 m high downhill slope attaining a speed of 3.92 m.s-1 before making a maximal double pole thrust on a force plate placed at the bottom of the slope. The vertical (F2), anterior-posterior (Fy) and mediolateral (Fx) reaction forces of the left pole were measured by the force plate. The positions of the pole were recorded in 3-D by an opto-electronic system. Thrust phase duration, impulse, mean force, velocity increase after pole thrust and pole angles were calculated from the recorded data. Double poling with long poles produced a significantly larger propulsive anterior-posterior reaction force impulse and velocity increase than normal (p < .05) and short poles (p < .05). This was in spite of a larger mean anterior-posterior reaction force being produced with short poles. Thus, thrust phase duration was a primary factor in determining propulsive anterior-posterior impulse. For the practitioner, the results can be useful in the selection of pole length when the aim is to increase thrust phase duration, anterior-posterior force impulse and velocity.

  • 56.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Karlsen, Jon
    A new device for evaluating distance and directional performance of golf putters.2006Inngår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 24, nr 2, s. 143-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 57.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Karlöf, Lars
    Jakobsen, Vidar
    A new device for measuring ski running surface force and pressure profiles2013Inngår i: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 16, nr 1, s. 55-59Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pressure/force acting between the running surface of a ski and the snow may indirectly change glide friction. Thus, measuring the pressure/force distribution may be important for a deeper understanding of glide in skiing. The present aim was to construct a device that allowed the pressure/force underneath the ski running surface (SRS) to be recorded. Pressure sensors were attached on top of a platform. Sheets of different materials were used to improve the interaction between the SRS and the sensors. Possible functions of the device are demonstrated in three applications that emphasized comparison of force distribution underneath skis selected for similarity, force distribution under both skis and a single ski as well as backward weight distribution. The results show that the device with the pressure sensors mapped pressure/force distribution underneath the skis in the applications presented, and the system can thus be a useful tool for further optimizing e.g., ski designs.

  • 58.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Kraepelien-Strid, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Seger, Jan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Friluftsliv och naturmiljöaktivitet i skolan2012Inngår i: Idrottsdidaktiska utmaningar / [ed] Larsson, H. & Meckbach, J, Stockholm, Stockholm: Liber, 2012, 2, s. 154-163Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 59.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Kraepelien-Strid, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Seger, Jan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Friluftsliv och naturmiljöaktiviteter i skolan2007Inngår i: Idrottsdidaktiska utmaningar, Stockholm: Liber , 2007, s. 154-163Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 60.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Lidberg, Martin
    Kombinationsträning med Martin Lidberg: 150 övningar som ger styrka, balans, koordination och kondition för idrottare och motionärer2007Bok (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Martin Lidberg ger här tillsammans med idrottsforskaren Johnny Nilsson en guidning i kombinationsträningens spännande och omväxlande värld. Alla som vill få en bättre basfysik och helhetsfysik har nytta av den här boken. Motionärer, idrottsaktiva på olika nivåer samt tränare får tillgång till ett stort kartotek av övningar som kan utveckla den egna respektive andras fysik. Oavsett om du är elitidrottare eller inte så mår du bra av att träna allsidigt, vilket också kan ge långsiktigt bra resultat.

  • 61.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Schantz, Peter
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Att utveckla idrottsundervisningen i skolan1990Inngår i: Undervisa i idrott: Idrottsämnets didaktik / [ed] Claes Annerstedt, Lund: Studentlitteratur , 1990, Vol. S. 152-158 : ill., s. 152-158Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 62.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Schantz, Peter
    Muskelfunktion vid löpning: variation i längd och funktion hos höft- och knäledsmuskulatur...1986Bok (Annet vitenskapelig)
  • 63.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Stokes, V P
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    A new method to measure foot contact.1985Inngår i: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 18, nr 8, s. 625-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new method to measure foot contact is described. It consists of a pressure sensitive transducer attached to one end of a flexible silicone rubber tube. A reliable indicator of foot contact is obtained with the tube glued to the outer perimeter of the sole of a shoe.

  • 64.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tesch, P
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Fatigue and EMG of repeated fast voluntary contractions in man.1977Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 101, nr 2, s. 194-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A fatigue test consisting of repeated fast maximal contractions of the left quadriceps muscle in an isokinetic apparatus was performed by 12 healthy male subjects (19-25 yrs). EMG signals recorded from the surface of the left vastus lateralis muscle, from which also biopsies were obtained for muscle fibre classification. Only minor changes were observed in the EMG variables despite a decrease in muscle strength performance, in terms of peak torque, work and power to about 50% of initial values after 100 contractions. The concomitantly obtained positive correlation between the increase in EMG/torque ratio and the individual percentage of fast twitch (FT) muscle fibres indicated that local factors in the muscle, primarily in FT fibres, were causing the development of fatigue during repeated dynamic contractions with high power outputs.

  • 65.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Adaptability in frequency and amplitude of leg movements during human locomotion at different speeds.1987Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 129, nr 1, s. 107-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study of human locomotion we investigate to what extent the normal frequency and amplitude of leg movements can be modified voluntarily at different constant velocities, and how these modifications are accomplished in terms of changes in duration and length of the support and swing phases of the stride cycle. Eight healthy male subjects performed walking and running on a motor-driven treadmill at speeds ranging from 1.0 to 3.0 m s-1 (walking) and 1.5 to 8.0 m s-1 (running), respectively. At each speed the subjects walked and ran with: normal stride frequency; the highest possible stride frequency, and the lowest possible stride frequency. Time for foot contact was measured with a special pressure transducer system under the sole of each shoe. At all speeds of walking and running it was possible to either increase or decrease the frequency of leg movements; that is, to decrease or increase stride cycle duration. The range of variation decreased with increasing speed. The mean overall stride frequency range was 0.41 (low frequency walk 1.0 m s-1)-3.57 Hz (high-frequency run 1.5 m s-1). Stride length ranged 0.40 (high frequency walk 1.0 m s-1)-5.00 m (low frequency run 6.0 m s-1). At normal frequency the overall ranges of stride frequency and length were 0.83-1.95 Hz and 1.16-4.10 m, respectively. The stride frequency increased with speed in low frequency walking and running (as in normal frequency) and decreased in high frequency, despite the effort to maintain extreme frequencies. Only in high frequency walking could the stride frequency be kept approximately constant.(ABSTRACT TRUNCATED AT 250 WORDS)

  • 66.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ground reaction forces at different speeds of human walking and running.1989Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 136, nr 2, s. 217-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study the variation in ground reaction force parameters was investigated with respect to adaptations to speed and mode of progression, and to type of foot-strike. Twelve healthy male subjects were studied during walking (1.0-3.0 m s-1) and running (1.5-6.0 m s-1). The subjects were selected with respect to foot-strike pattern during running. Six subjects were classified as rearfoot strikers and six as forefoot strikers. Constant speeds were accomplished by pacer lights beside an indoor straightway and controlled by means of a photo-electronic device. The vertical, anteroposterior and mediolateral force components were recorded with a force platform. Computer software was used to calculate durations, amplitudes and impulses of the reaction forces. The amplitudes were normalized with respect to body weight (b.w.). Increased speed was accompanied by shorter force periods and larger peak forces. The peak amplitude of the vertical reaction force in walking and running increased with speed from approximately 1.0 to 1.5 b.w. and 2.0 to 2.9 b.w. respectively. The anteroposterior peak force and mediolateral peak-to-peak force increased about 2 times with speed in walking and about 2-4 times in running (the absolute values were on average about 10 times smaller than the vertical). The transition from walking to running resulted in a shorter support phase duration and a change in the shape of the vertical reaction force curve. The vertical peak force increased whereas the vertical impulse and the anteroposterior impulses and peak forces decreased. In running the vertical force showed an impact peak at touch-down among the rearfoot strikers but generally not among the forefoot strikers. The first mediolateral force peak was laterally directed (as in walking) for the rearfoot strikers but medially for the forefoot strikers. Thus, there is a change with speed in the complex interaction between vertical and horizontal forces needed for propulsion and equilibrium during human locomotion. The differences present between walking and running are consequences of fundamental differences in motor strategies between the two major forms of human progression.

  • 67.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Halbertsma, J
    Changes in leg movements and muscle activity with speed of locomotion and mode of progression in humans.1985Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 123, nr 4, s. 457-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Knowledge of adaptations to changes in speed and mode of progression (walking-running) in human locomotion is important for an understanding of underlying neural control mechanisms and allows a comparison with more detailed animal studies. Leg movements and muscle activity patterns were studied in ten healthy males (19-29 yr) during level walking (0.4-3.0 m X s-1) and running (1.0-9.0 m X s-1) on a motor-driven treadmill. Movements were recorded in the sagittal plane with a Selspot optoelectronic system. Recordings of EMG were made from seven different muscles of one leg by means of surface electrodes. Durations, amplitudes and relative phase relationships of angular displacements and EMG activity were analysed in relation to different phases of the stride cycle (defined by the leg movements). The durations of the entire stride cycle and of the support phase were found to decrease curvilinearly with velocity. Swing and support phase durations were linearly related to cycle duration in walking, and curvilinearly related in running. The characteristic occurrence of double support phases in walking was also seen in very slow running. Support length increased with speed up to about 1.2 m both in walking and running, but was longer in walking at the same velocity. Increases in net angular displacements were largest for hip movements and for knee flexion-extension during the swing phase in running. With increasing velocity a clear shift in relative rectus femoris activity occurred from knee extension to hip flexion. Gastrocnemius lateralis (LG) was co-activated with the other leg extensors prior to foot contact in running, whereas in walking LG was not turned on until later in the support phase. The ankle flexor tibialis anterior had its main peak of activity after touch-down in walking and before touch-down in running. The same basic structure of the stride cycle as in other animals suggests similarities in the underlying neural control. Human speed adaptation is distinguished primarily by an increase in both frequency and amplitude of leg movements and by a possibility of changing between a walking and a running type of movement pattern.

  • 68.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tinmark, Fredrik
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Halvorsen, Kjartan
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing2013Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, nr 6, s. 1385-1394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study incorporated variations in speed and the horizontal resistance acting upon elite female skiers during double poling (DP) on a treadmill and specifically analyzed biomechanical adaptations to these variations. Whole body kinematics and pole force data were recorded and used to calculate the moment of force acting on the shoulder and elbow joints. Data were obtained with a 3D optoelectronic system using reflective markers at given anatomical landmarks. Forces along the long axis of the right pole were measured with a piezoelectric force transducer. Surface electrodes were used to record EMG activity in the rectus femoris, rectus abdominis, latissimus dorsi and triceps brachii muscles. In a first set of recordings, the participants double poled with zero elevation at five different speeds from 8 to 17 km h−1. In a second set of recordings, horizontal resistance was added by weights (0.4–1.9 kg) attached to a pulley system pulling the skier posteriorly during DP at 14 km h−1. Results showed increasing relative duration of the thrust phase with increasing resistance, but not with speed. Significant kinematic differences occurred with increase in both speed and resistance. The mean (±SD) horizontal force components ranged between 1.7 (±1.3) and 2.8 (±1.1) percent (%) bodyweight (BW) in the speed adaptation and 3.1 (±0.6) and 4.0 (±1.3) % BW in the adaptation to horizontal resistance. Peak muscle activity showed a central to peripheral (proximo-distal) activation sequence. The temporal cycle phase pattern in the adaptation to speed and horizontal resistance differed.

  • 69.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tveit, Per
    Eikrehagen, Olav
    Effects of speed on temporal patterns in classical style and freestyle cross-country skiing.2004Inngår i: Sports biomechanics / International Society of Biomechanics in Sports, ISSN 1476-3141, Vol. 3, nr 1, s. 85-107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [ar]

    The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross-country skiing techniques. Eight skilled male cross-country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross-country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self-selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross-country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross-country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross-country skiing techniques.

  • 70.
    Oddsson, Kristjan
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Danielsson, Evelina
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Björn Ekbloms forskningsgrupp.
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH. Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Wahlgren, Lina
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Development of physical tests and ratings scales of perceived health in a project with supervised physical activity for elderly.2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Background: Valid and reliable field tests for measuring physical fitness and different health parameters is an important matter for evaluating effects of exercise interventions.

    Purpose: The aim was to study different test parameters such as aerobic capacity, strength, perceived health and life style habits, such as physical activity, in a physical activity intervention for elderly people.

    Method: 117 old-age pensioners (99 women and 18 men). Their mean age (yrs) and BMI (kg/m2 ) was 74 and 26 for the women and 73 and 25 for the men, respectively. Different aerobic, strength and balance tests were measured. Guided physical activity (nordic walking, strength training, aqua gymnastics), were given 45-60 min, 2 times/week for 8-12 weeks. Perceived exertion ratings during the exercises were moderate and/or strong.

    Results: Significant changes (p< 0,05) were seen between pre- and post tests regarding all physical tests except the balance test for men. Even the perceived physical and mental health significantly improved. The mean values for questions concerning self reported inactive/active life style, including sedentary time, were changed to a more active life style.

    Conclusion: 8-12 weeks of guided physical activity can improve several physiological parameters which are positively correlated to decreased risk of numerous diseases. More research is needed to develop reliable and valid field tests for physical capacity and different health parameters.

  • 71. Quennerstedt, Mikael
    et al.
    Gibbs, Beatrice
    Almqvist, Jonas
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Winther, Helle
    Beatrice: dance video games as a resource for teaching dance2016Inngår i: Digital technologies and learning in physical education: pedagogical cases / [ed] Ashley Casey, Victoria A. Goodyear, Kathleen M. Armour, Routledge, 2016, s. 69-85Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 72.
    Rosdahl, Hans
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lindberg, Thomas
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Edin, Fredrik
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    The Moxus Modular metabolic sustem evaluated with two sensors for ventilation against the Douglas bag method2013Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, nr 5, s. 1353-1367Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study evaluated the Moxus metabolic system with the Douglas bag method (DBM) as criterion. Reliability and validity were investigated in a wide range of ventilation and oxygen uptake and two sensors for determining ventilation were included. Thirteen well-trained athletes participated in one pre-test and four tests for data collection, exercising on a cycle ergometer at five submaximal powers (50-263 W) and at [Formula: see text]. Gas exchange variables were measured simultaneously using a serial setup with data collected on different days in an order randomized between Moxus with pneumotachometer (MP) and turbine flowmeter (MT) sensors for ventilation. Reliability with both sensors was comparable to the DBM. Average CV (%) of all exercise intensities were with MP: 3.0 ± 1.3 for VO(2), 3.8 ± 1.5 for VCO(2), 3.1 ± 1.2 for the respiratory exchange ratio (RER) and 4.2 ± 0.8 for V (E). The corresponding values with MT were: 2.7 ± 0.3 for VO(2), 4.7 ± 0.4 for VCO(2), 3.3 ± 0.9 for RER and 4.8 ± 1.4 for V (E). Validity was acceptable except for small differences related to the determination of ventilation. The relative differences in relation to DBM at the powers including [Formula: see text] were similar for both sensors with the ranges being: +4 to -2 % for V (E), +5 to -3 % for VO(2) and +5 to -4 % for VCO(2) while RER did not differ at any power. The Moxus metabolic system shows high and adequate reliability and reasonable validity over a wide measurement range. At a few exercise levels, V (E) differed slightly from DBM, resulting in concomitant changes in VO(2) and VCO(2).

  • 73.
    Rosdahl, Hans
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Contribution of leg muscle forces to paddle stroke force and kayak speed during maximal effort flat-water paddling among elite kayakers2015Inngår i: Book of abstracts: 20th annual Congress of the European College of Sport Science, ECSS Malmö 2015, 2015, s. 318-319Konferansepaper (Annet vitenskapelig)
  • 74. Rud, Bjarne
    et al.
    Secher, N H
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Smith, G
    Hallén, J
    Metabolic and mechanical involvement of arms and legs in simulated doule pole skiing2014Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, nr 6, s. 913-919Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We evaluated arm and leg work rate and metabolism during double pole ergometer skiing. Thermodilution arm and leg blood flow was determined together with the arterial to venous difference for oxygen, while the work rate was assessed in eight male recreational skiers [24 (SD 7) years]. When work rate increased from 82 (SE 4) to 117 (7) W, leg power increased by 43% (enhanced vertical force and displacement of the body). The elbow angle tended to increase [from 71 (11.3)° to 75 (10.9)°; P = 0.07] and arm oxygen uptake increased by 20 (5)% [from 0.65 (0.07) to 0.78 (0.08) L/min; P < 0.05] because two-arm blood flow increased [from 5.4 (0.6) to 6.3 (0.7) L/min; P < 0.05] with no significant change in oxygen extraction [from 59 (2.3)% to 60 (1.9)%] accompanied with net arm lactate and potassium release. In contrast, two-leg blood flow [from 5.8 (0.5) to 8.0 (0.5) L/min] and oxygen extraction [from 67 (1.3)% to 75 (1.5)%] increased (P < 0.05), resulting in a 53 (8)% increase in leg oxygen uptake [from 0.82 (0.06) to 1.24 (0.07) L/min; P < 0.05]. In conclusion, during double poling on an ergometer, arm muscle metabolism and work rate increase only marginally and an increase in work intensity is covered mainly by the leg muscles.

  • 75.
    Schantz, Peter
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, FoU-gruppen för rörelse, hälsa och miljö.
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Exempel på integrering av idrott och biologi1986Inngår i: Tidskrift i gymnastik och idrott : officiellt organ för Svenska g, ISSN 0281-5338, nr 4, s. 29-35Artikkel i tidsskrift (Annet vitenskapelig)
  • 76.
    Schantz, Peter
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Skolans kroppsövningar i obalans: tillför en konstnärlig dimension1990Inngår i: Tidskrift i gymnastik och idrott : officiellt organ för Svenska g, ISSN 0281-5338, nr 6, s. 10-17Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    År 1989 inledde artikelförfattarna en målsättningsdiskussion med lärarkollegerna på Gymnastik- och idrottshögskolan i Stockholm (GIH). Vad skulle lärarutbildningen innehålla för moment, ämnen och rörelsepraktiker. En analys av lärarutbildningen sedan 1813 visualiserades i en modell av kroppsövningsfältet. Författarna värderar skolans kroppsövningsämne och bedömer att det behöver utvecklas. 

  • 77.
    Seger, Jan
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Hård af Segerstad, Kristina
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    GIH:s rullskidprojekt:  Lärarstudenter GIH 2008 delrapport 2: 20092010Rapport (Annet vitenskapelig)
    Abstract [sv]

    Gymnastik – och idrottshögskolan, GIH, har en lång tradition av utbildning inom skidåkning. Redan 1924 genomfördes den första fjällfärden för civila studenter i Jämtland och sedan 1926 har obligatorisk utbildning i turteknik, förlagd till fjällterräng, genomförts (Schantz & Halldén, 1988). Utförsåkning och längdåkning har också länge funnits med som inslag i vinterutbildningen. För närvarande har samtliga program vid GIH (lärarprogrammet, tränarprogrammet och hälsopedagogprogrammet) en obligatorisk vinterutbildning i fjällmiljö, omfattande omkring tre högskolepoäng (cirka två veckors heltidsstudier).

    Under senare år har en ökande andel av de antagna studenterna uppvisat brister vad gäller grundläggande skidfärdighet, vilket försvårat möjligheterna till breddning och fördjupning, såväl teoretiskt som praktiskt, under vinterutbildningen. De stora skillnaderna i färdighet hos studenterna innebär, förutom svårigheterna att tekniskt och didaktiskt arbeta med olika aspekter av skidåkning med heterogena grupper under en så begränsad tid, även att säkerheten under turåkningsmomentet får större fokus än vad som tidigare varit fallet. Den bristande skidåkningsfärdigheten hos vissa studenter kan bland annat få till följd att de får svårt att genomföra turåkningen. Den vanligtvis otillräckliga snötillgången i Mellansverige gör att träning på "hemmaplan" blir svår att genomföra.

    I syfte att söka komma till rätta med denna problematik genomfördes ett delprojekt inom ramen för det så kallade "GIH 2008-projektet". Studenter som själva ansåg sig ha en bristande skidteknik, eller betraktade sig som nybörjare i skidåkning, erbjöds delta i projektet. Utöver möjligheten att stödja studenter som saknade eller hade liten tidigare erfarenhet av skidåkning, fanns här möjlighet att prova olika metodiker för didaktiska studier.

    Denna åtgärd från GIH:s sida att bistå studenter som av geografiska, klimatologiska eller av andra orsaker inte haft möjlighet att tidigare skaffa sig skiderfarenhet kommer sannolikt att bli än mer betydelsefull i framtiden.

    Nedan presenteras data för stakmomentet och diagonalåkningen i projektet. Ett antal utrustningar, bestående av skidskor, stavar och rullskidor införskaffades och studenterna fick en möjlighet att under några veckor träna rullskidåkning

    Såväl kvalitativa som kvantitativa metoder användes för utvärdering av träningsprocesser. Denna utvärdering baserades på videofilmning och datorbaserad videoanalys.

  • 78.
    Stålman, Cecilia
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Karolinska institutet.
    Ryhed, Anna
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Godhe, Manne
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    A novel aerobic test, 5-minute-pyramid-test, useful in school to monitor VO2max2019Inngår i: AISEP International Conference 2019 Book of abstracts, 2019, s. 402-Konferansepaper (Annet vitenskapelig)
  • 79.
    Thorstensson, Alf
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Carlson, H
    Zomlefer, M R
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lumbar back muscle activity in relation to trunk movements during locomotion in man.1982Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 116, nr 1, s. 13-20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The function of lumbar back muscles was studied by relating their activity patterns to trunk movements in 7 healthy adult males during normal walking (1.0-2.5 m/s) and running (2.0-7.0 m/s) on a treadmill. The movements of the trunk in the sagittal and frontal planes were recorded with a Selspot optoelectronic system using infrared light emitting diodes as markers. The electromyographic (EMG) activity from the two main portions of the lumbar erector spinae muscles (Multifidus and Longissimus) was recorded bilaterally with intramuscular wire electrodes. The angular displacements of the trunk showed regular oscillations, but their shape, magnitude and relation to the step cycle were different in the two planes (sagittal and frontal) and varied with speed and mode of progression. The EMG pattern in both muscles showed a bilateral cocontraction with two main bursts of activity per step cycle starting just before each foot was placed on the ground. Relating the EMG to the movements of the trunk indicated that the main function of the lumbar erector spinae muscles is to restrict excessive trunk movements. During walking this restricting action is most evident for movements in the frontal plane, whereas in running the lumbar back muscles mainly control the movements in the sagittal plane.

  • 80.
    Thorstensson, Alf
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Trunk muscle strength during constant velocity movements.1982Inngår i: Scandinavian Journal of Rehabilitation Medicine, ISSN 0036-5505, E-ISSN 1940-2228, Vol. 14, nr 2, s. 61-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new apparatus has been designed for standardized measurements of the strength of human trunk muscles utilizing the isokinetic (constant movement velocity) technique (Cybex). It is possible to measure the produced torque during maximal voluntary isometric and isokinetic contractions in the whole range of motion during flexion, extension and lateral flexion of the trunk. Effects of gravity are eliminated since the movements are performed in the horizontal plane. Torque can be measured around different centres of rotation of the body. With this experimental set-up the strength of the trunk muscles has been characterized in a group of 14 normal male subjects (18-31 yrs). The torque produced by the trunk muscles varied with movement velocity and trunk position in the arc of motion. Peak torque occurred in a position where the muscles involved were stretched. The strength of the trunk extensors exceeded that of the flexors, but the degree (ratio) varied with trunk position. The relative contribution of the hip muscles to the total torque produced with the centre of rotation at the hip joint was larger for flexors than for extensors and varied with velocity and position. It is concluded that the present technique is useful to characterize the human trunk muscles.

  • 81.
    Wecke, Liliane
    et al.
    Dep of Cardiology, Karolinska sjukhuset & Karolinska Institutet.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Lundahl, Gunilla
    Bergfeldt, Lennart
    Younger People Show More Changes in Repolarization with Exercise2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Background:

    Cardiac repolarization is a complex phenomenon that depends on heart rate (HR), autonomic nervous system (ANS) activity, age, gender and diseases/pathological conditions etc. Cardiovascular events in LQT1 mutation carriers are also typically related to age, gender, and QT interval, and are triggered by physical exercise. We studied the repolarization response to heavy exercise in healthy subjects.

    Material and methods:

    Vectorcardiography (VCG) was recorded with the Coronet II system (Ortivus AB, Danderyd, Sweden) using the Frank orthogonal leads (X, Y and Z) at supine rest before and after a maximal cycle ergometer test in 42 healthy subjects. They were of different age and gender, 21 old (64-79 years) and 21 young (20-32 years), 23 were women and 19 men. Maximum T-vector amplitude and direction were assessed as well as T-area, QTc-interval and other VCG parameters.

    Results:

    At baseline most parameters differed between old and young subjects, but only QRS-duration, QRS-area and T-amplitude between women and men. Younger subjects had lower HR (59 vs 72 bpm; p<0.01), higher T-amplitude (530 vs 395 μV; p<0.01), larger T-area (73 vs 48 μVs; p<0.001), shorter QTc (417 vs 430 ms; p<0.01) and a narrower QT-angle (25 vs 59°; p<0.01).

    The response to strenuous exercise was much more pronounced in the younger subjects with an increase in resting HR by 35 bpm compared with 17 bpm for the old subjects (p<0.001). This was accompanied by a more pronounced decrease in T-amplitude (-138 vs -27 μV; p<0.01) and T-area (-20 vs -7 μVs; p<0.01) but a larger prolongation of QTc (54 vs 10 ms; p<0.001).

    Conclusion:

    Young people seem to have a more active ANS, which results in a more pronounced repolarization response to heavy exercise. This might explain why patients with LQT1 more likely suffer from malignant arrhythmias at ages below 40 years.

  • 82.
    Wecke, Liliane
    et al.
    Dept of Cardiology, Karolinska sjukhuset & Karolinska Institutet.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Lundahl, Gunilla
    Bergfeldt, Lennart
    Younger People Show More Changes in Repolarization with Exercise2012Inngår i: Younger People Show More Changes in Repolarization with Exercise, 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Purpose:

    Cardiac repolarization is a complex phenomenon that depends on heart rate (HR), autonomic nervous system (ANS) activity, age, gender and diseases/pathological conditions etc. Cardiovascular events in LQT1 mutation carriers are also typically related to age, gender, and QT interval, and are triggered by physical exercise. We studied the repolarization response to heavy exercise in healthy subjects.

    Method:

    Vectorcardiography (VCG) was recorded with the Coronet II system (Ortivus AB, Danderyd, Sweden) using the Frank orthogonal lead system (X, Y and Z) at supine rest before and after a maximal cycle ergometer test in 42 healthy subjects. They were of different age and gender, 21 old (64-79 years) and 21 young (20-32 years), 23 were women and 19 men. Maximum T-vector amplitude and direction were assessed as well as T-area, QTc-interval and other VCG parameters.

    Summary:

    At baseline most parameters differed between old and young subjects, but only QRS-duration, QRS-area and T-amplitude between women and men. Younger subjects had lower HR (59 vs 72 bpm; p<0.01), higher T-amplitude (530 vs 395 μV; p<0.01), larger T-area (73 vs 48 μVs; p<0.001), shorter QTc (417 vs 430 ms; p<0.01) and a narrower QT-angle (25 vs 59°; p<0.01).

    The response to strenuous exercise was much more pronounced in the younger subjects with an increase in resting HR by 35 bpm compared with 17 bpm for the old subjects (p<0.001). This was accompanied by a more pronounced decrease in T-amplitude (-138 vs -27 μV; p<0.01) and T-area (-20 vs -7 μVs; p<0.01) but a larger prolongation of QTc (54 vs 10 ms; p<0.001).

    Conclusion:

    Young people seem to have a more active ANS, which results in a more pronounced repolarization response to heavy exercise. This might explain why patients with LQT1 more likely suffer from malignant arrhythmias at ages below 40 years.

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