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  • 1
    Electronic Resource
    Electronic Resource
    Mechanical properties of passive rat muscle during sinusoidal stretching (1987)
    Springer
    Pflügers Archiv 409 (1987), S. 438-447 
    Details
    ISSN: 1432-2013
    Keywords: Hysteresis diagrams ; Muscle dimensions ; Passive force ; Sinusoidal stretching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The dynamic passive response of the left gastrocnemius medialis muscle of thirty male Wistar rats was studied as a function of muscle dimensions and absolute and relative amount of connective tissue. Values of the absolute active and passive length-force curves (active force, passive force, active working range) correlated well (coefficients of correlation in a range of 0.62–0.92) with morphological variables (such as muscle optimum length, mean muscle fibre optimum length, physiological cross section, muscle weight and amount of intramuscular connective tissue). To eliminate dimensional effects the active and passive length-force curves were normalized taking maximal active twitch force and muscle optimum length as reference values (100%). The width of the normalized active length-force curve (relative active working range) was correlated negatively with muscle weight, muscle optimum length and physiological cross section. Relative amount of connective tissue and passive tension at optimum length (both independent of muscle dimensions) were positively correlated, indicating that passive muscles are stiffer when relative amount of intramuscular connective tissue is higher. Sinusoidal movements with several amplitudes and frequencies of movement were imposed on the passive gastrocnemius medialis muscle over a range of muscle lengths. In accordance with the approximately exponential increase of static passive muscle force with length, muscle length has a large influence on the shape and magnitude of the hysteresis diagrams resulting from sinusoidal movements: the value of all variables selected increases approximately exponentially with muscle length with the exception of the value of loss tangent, a factor indicating the amount of energy dissipated during each cycle relative to the amount of energy stored and released elastically. Velocity of movement has only minor influence on variables of the hysteresis diagrams as is shown by changing the frequency of movement. As loss tangent and relative amount of connective tissue did not vary with muscle dimensions in the muscles studied, it is likely that material properties of the components causing passive resistance were similar in these muscles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583799
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  • 2
    Electronic Resource
    Electronic Resource
    Supramaximal test results of male and female speed skaters with particular reference to methodological problems (1988)
    Springer
    European journal of applied physiology 57 (1988), S. 6-9 
    Details
    ISSN: 1439-6327
    Keywords: Power output ; Oxygen consumption ; Male/female comparison ; Bicycle ergometer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six male and six female elite speed skaters were tested during two bicycle ergometer tests: a 30 s sprint test and a 2.5 min supra maximal test. During the 2.5 min test oxygen consumption was measured every 30 s. The males showed 30–31% higher mean power output values both during the sprint test (1103 versus 769 Watt) and during the 2.5 min test (570 versus 390 Watt). Maximal oxygen consumption was 31% higher for the males than for the females (5.10 versus 3.50 l · min−1). However, when expressed per kilogram lean body weight (LBM), power output and oxygen consumption was equal for both sexes. Differences between present and previous results are most likely due to methodological problems with the estimation of load during the supra maximal test. Subjects appear to experience difficulties in distributing their power output over the 2.5 min if they are tested for the first time. For experienced skaters and cyclists, fixed levels of 19 W · kgLBM−1 as initial load setting for the sprint test and 8 W · kg LBM−1 for the 2.5 min test are recommended.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691230
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  • 3
    Electronic Resource
    Electronic Resource
    Positive work as a function of eccentric load in maximal leg extension movements (1986)
    Springer
    European journal of applied physiology 55 (1986), S. 562-568 
    Details
    ISSN: 1439-6327
    Keywords: Elastic energy ; Pre-stretch ; Human muscles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Negative and positive work performed during leg extension movements of 53 well trained subjects was measured with the help of a special dynamometer. The subjects performed four maximal push off trials against five different loads (25–105 kg): two two-legged extensions from a squatting position (SM) with a knee angle of 70
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00421653
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  • 4
    Electronic Resource
    Electronic Resource
    Physiological and biomechanical comparison of roller skating and speed skating on ice (1987)
    Springer
    European journal of applied physiology 56 (1987), S. 562-569 
    Details
    ISSN: 1439-6327
    Keywords: Speed skating ; Roller skating ; Training specificity ; Biomechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eight well trained marathon skaters performed all-out exercise tests during speed skating on ice and roller skating. To compare these skating activities in relation to the concept of training specificity, relevant physiological (V O2,V E, RER and heart rate) and biomechanical variables (derived from film and video analysis) were measured. There were no significant differences between oxygen uptake (50.5±8.0 and 53.3±6.7 ml·min−1·kg−1), ventilation (102.4±11.2 and 116.0±11.1 l·min−1) or heart rate (174±12.2 and 176±14.5 min−1) between speed and roller skating. In roller skating a higher RER (1.16±0.1 cf. 1.05±0.1) was found. Power, work per stroke and stroke frequency were equal. Due to a higher coefficient of friction the maximal roller skating speed was lower. The effectiveness of push-off and parameters concerning the skating techniques showed no differences. In roller skating a 7.5% higher angle of the upper leg in the gliding phase occurred. It is speculated that the blood flow through the extensor muscles might be higher in roller skating. It is concluded that roller skating can be considered as a specific training method which may be used by trained speed skaters in the summer period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00635371
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  • 5
    Electronic Resource
    Electronic Resource
    Supramaximal cycle tests do not detect seasonal progression in performance in groups of elite speed skaters (1992)
    Springer
    European journal of applied physiology 64 (1992), S. 292-297 
    Details
    ISSN: 1439-6327
    Keywords: Aerobic power ; Anaerobic power ; Training
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Seven female and eight male elite junior skaters performed cycle ergometer tests at four different times during the 1987/1988 season. The tests consisted of a Wingate-type 30-s sprint test and a 2.5-min supramaximal test. The subjects were tested in February, May and September 1987 and in January 1988. Maximal oxygen consumption was measured during the 2.5-min test. With the exception of the maximal oxygen consumption of the women in May which was about 6% lower than in the other three tests, no seasonal changes in the test results could be observed —this, in spite of a distinct increase in training volume (from 10 to more than 20 h · week−1) and training intensity in the course of the season. When the test data were compared to those of elite senior skaters, it appeared that the junior skaters showed the same values for mean power output during the sprint test [14.2 (SD 0.4) W · kg−1 for the men and 12.6 (SD 0.5) W · kg−1 for the women] and maximal oxygen consumption [63.1 (SD 2.8) ml· kg−1 · min−1 for the men and 55.3 (SD 3.5 ml · kg−1 · min−1 for the women, respectively] as found for senior skaters. It seemed, therefore, that the effects of training in these skaters had already levelled off in the period before they participated in this investigation. In contrast to previous studies, no relationship could be shown between the test results and skating performance. This was most likely due to the homogenous character of the groups (mean standard deviations in power and oxygen consumption were only 5%). It was concluded that the present cycle tests used to measure aerobic and anaerobic power were obviously not of use in evaluating seasonal changes in performance in these groups of highly trained athletes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00636214
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  • 6
    Electronic Resource
    Electronic Resource
    Some technical, physiological and anthropometrical aspects of speed skating (1983)
    Springer
    European journal of applied physiology 50 (1983), S. 343-354 
    Details
    ISSN: 1439-6327
    Keywords: Aerobic capacity ; Performance level ; Efficiency ; Bicycle-ergometry ; Friction forces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five elite speed skaters and fourteen well trained skaters of a lower performance level performed three maximal tests: a 3,000 m race from which the skating position and the stroke frequency were derived, an oxygen consumption test both during skating and during a bicycle ergometer test. From all subjects anthropometric measures were taken. The elite group showed a $$\dot V$$ o2 during cycling of 64.4±3.5 ml·kg−1·min−1 and 59.4±3.7 ml·kg−1·min−1 during skating. The elite skaters showed: a shorter upper leg length with respect to total leg length, higher aerobic power during cycling, higher stroke frequency, smaller pre-extension knee angle coupled to higher work per stroke, higher “efficiency” during skating and higher external power during skating and during cycling when compared with the group of lower performance level. It is concluded that an important pre-requisite for speed skating appears to be the possibility to skate at a small pre-extension knee angle without an excessive claim to anaerobic metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423240
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  • 7
    Electronic Resource
    Electronic Resource
    Differences in oxygen consumption and external power between male and female speed skaters during supramaximal cycling (1983)
    Springer
    European journal of applied physiology 51 (1983), S. 337-345 
    Details
    ISSN: 1439-6327
    Keywords: External power ; Efficiency ; Speed skating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Differences in performance levels between elite male and female endurance athletes are often explained by differences found in $$\dot V_{O_2 } $$ max even when expressed in $$\dot V_{O_2 } $$ max per kilogram lean body mass ( $$\dot V_{O_2 } $$ /LBM). Such an explanation is only a matter of course when less or no difference exists in mechanical efficiency, anaerobic power and technical variables like friction constants between males and females, particularly during supramaximal exercises. In this study five elite male speed skaters were compared with five elite female speed skaters with respect to oxygen consumption and external power during a 3 min supramaximal bicycle ergometer test. The training background and training history of both groups were comparable. Although the elite males showed a 20% higher $$\dot V_{O_2 } $$ /BW and 8% higher $$\dot V_{O_2 } $$ /LBM (71.0 versus 65.0 1·min−1·kg−1) than the females, the female group showed the same mean external power Pc per kilogram bodyweight, and a surprising 12% higher PC/LBM than the males (6.47 versus 5.79 W·kg−1). Hence the female group delivered 22% more external power per liter of oxygen consumption. With the help of additional data from 14 male and 11 female sub-elite skaters it is shown that the differences between the elite groups are mainly due to sex differences. In the light of differences between men and women reported in other studies, it seems likely that the differences found in this study are due to a difference in mechanical efficiency which particularly occurs in supramaximal tasks. With respect to skating performance, it is concluded that the difference in performance level between elite male and female skaters will mainly be determined by differences in skating technique and in frictional losses, and not by differences in work capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429070
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  • 8
    Electronic Resource
    Electronic Resource
    Biomechanical analysis of drop and countermovement jumps (1986)
    Springer
    European journal of applied physiology 54 (1986), S. 566-573 
    Details
    ISSN: 1439-6327
    Keywords: Countermovement jump ; Drop jump ; Biomechanics ; Electromyography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle joints. In addition, electromyograms were recorded from five muscles in the lower extremity. The results obtained for DJ appeared to depend on jumping style. In a subgroup of subjects making a movement of large amplitude (i. e. bending their hips and knees considerably before pushing off) the push-off phase of DJ closely resembled that of CMJ. In a subgroup of subjects making a movement of small amplitude, however, the duration of the push-off phase was shorter, values for moments and mean power output at the knees and ankles were larger, and the mean EMG activity of m. gastrocnemius was higher in DJ than in CMJ. The findings are attributed to the influences of the rapid pre-stretch of knee extensors and plantar flexors after touch-down in DJ. In both subgroups, larger peak resultant reaction forces were found at the knee and ankle joints, and larger peak forces were calculated for the Achilles tendon in DJ than in CMJ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00943342
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  • 9
    Electronic Resource
    Electronic Resource
    Electromechanical delay in the vastus lateralis muscle during dynamic isometric contractions (1990)
    Springer
    European journal of applied physiology 60 (1990), S. 467-471 
    Details
    ISSN: 1439-6327
    Keywords: Electromechanical delay ; Contraction delay ; Relaxation delay ; Cross-correlation technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electromechanical delay (EMD) values were obtained using a cross-correlation technique for a series of 14 repetitive submaximal dynamic isometric contractions of the vastus lateralis performed by five subjects. To avoid a phase lag, which is introduced with one-way filtering, the EMG was processed with a bi-directional application of a second-order Butterworth filter. A mean EMD value of 86 ms (SD=5.1 ms) was found. Moreover, contraction and relaxation delays were computed and compared. There was a significant difference between the contraction and relaxation delays (P〈0.005). The mean contraction delay was 81.9 ms and the mean relaxation delay was 88.8 ms. Despite this significant difference, the computed contraction and relaxation delay values lie in the same range as the total phase lag, calculated with the cross-correlation technique. The magnitude of EMD values found supports the need to account for this delay when interpreting temporal aspects of patterns of intermuscular coordination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705038
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  • 10
    Electronic Resource
    Electronic Resource
    Determination and interpretation of mechanical power in human movement: application to ergometer cycling (1990)
    Springer
    European journal of applied physiology 61 (1990), S. 11-19 
    Details
    ISSN: 1439-6327
    Keywords: Power equation ; External power ; Efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Based on a model consisting of three rigid links, an instantaneous power equation has been deduced for ergometer cycling which shows a causal relationship between power liberated in joint rotation on the one hand and the rate of change of segmental energy plus the power transferred to the pedal on the other. The shape and magnitude of these two types of power have been calculated by measurements of pedal force and cinematographic analysis and the results show fair agreement between them. When cycling at a mean exercise intensity of 340 W at 90 rpm, less than 28 W appears to be lost in the (necessary) changes of segmental energies. It is suggested that power liberated in the joints should be judged as the source of power in the power equation. It is, therefore, proposed that this power should be defined as external power in this and other human movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236687
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