Tracheostoma valves are used to make hand-free speaking possible for persons who have undergone a... more Tracheostoma valves are used to make hand-free speaking possible for persons who have undergone a laryngectomy. To design and test a new tracheostoma valve to improve existing tracheostoma valves. The tracheostoma valve closes by means of strong inhalation so that all the air that is exhaled is available for phonation. The device automatically stays in the “speak-position” until the patient deliberately changes the device to the “breathing position” by a fast expiration. If all the air that has been exhaled has been consumed during phonation, the patient can inhale again, without changing the device, because a small valve automatically opens, thus allowing phonation without time limits. An experimental setup with a computer-based acquisition program was used to measure the pressure at which the valve opened and the flow at which the valve closed. The pressure and flow needed to open and close the magnetic adjustable valve were measured for different positions and contained in the co...
A treadmill with four force transducers was used to analyze gait during running. 39 volunteers ra... more A treadmill with four force transducers was used to analyze gait during running. 39 volunteers ran on a treadmill until they were exhausted. The step parameter variances showed a very distinct change in time. 17 subjects showed a sudden increase in variance. The other 22 subjects did not show such an effect, probably because they stopped too soon. This was confirmed by lactate measurements. In conclusion, the described treadmill is able to register continuously the running pattern of healthy volunteers. During an exhausting exercise, the running pattern becomes irregular in the last phase of the exercise.
It is known that the concentrations of ammonia and lactate in blood increase during incremental e... more It is known that the concentrations of ammonia and lactate in blood increase during incremental exercise. Sweat also contains lactate and ammonia. The aim of the present study was to investigate the physiological response of lactate and ammonia in plasma and sweat during a stepwise incremental cycle ergometer exercise test in ten subjects. During this test lactate and ammonia were measured in blood obtained from the earlobe and in sweat collected in a bag attached to the back of the subject. At the end of each interval this bag was emptied for measuring lactate and ammonia. A disproportional increase in the concentration of lactate and ammonia in blood was found, in sweat a disproportional decrease. The lactate concentrations in sweat were higher than those in blood. We hypothesise that lactate in sweat is produced from glycogen granules of the clear cell of the eccrine gland. This lactate production results in acidification of sweat, which facilitates the diffusion of ammonia from eccrine duct cell to duct lumen. It is uncertain how far duct cell ammonia originates from plasma, the duct cell itself might produce ammonia. Part of the ammonia in sweat could come from the breakdown of urea by skin bacteria.
The aim of this study was to investigate whether the increase of ammonia concentration and lactat... more The aim of this study was to investigate whether the increase of ammonia concentration and lactate concentration in blood was accompanied by an increased expiration of ammonia during graded exercise. Eleven healthy subjects performed an incremental cycle ergometer test. Blood ammonia, blood lactate and the amount of expired ammonia were measured until 30 minutes post exercise. The expired air was guided through a flow chamber filled with a sulphuric acid solution to trap the expired ammonia. Blood ammonia, blood lactate increased more than proportionally and the amount of expired ammonia (in micromol/min) increased exponentially with the workload. Post-exercise the amount of expired ammonia decreased within a few minutes back to pre-exercise levels while the concentrations of lactate and ammonia in blood decreased much more slowly and were still elevated after 30 minutes of recovery. We conclude that the more than proportional increase of ammonia and lactate during graded exercise, ...
Iedereen weet dat als je je lichamelijk inspant, je vroeg of laat door vermoeidheid moet stoppen.... more Iedereen weet dat als je je lichamelijk inspant, je vroeg of laat door vermoeidheid moet stoppen. Zeer zware inspanningen kunnen kort volgehouden worden. Lichte inspanningen daarentegen heel lang. In dit artikel wordt de vermoeidheid belicht. Ook wordt beschreven wat er bij inspanning zoal gemeten kan worden aan het lichaam. Bij een gegeven inspanningsintensiteit defi-nie¨ren we vermoeidheid als het gevoel dat het steeds meer moeite kost om de inspanning vol te houden (increased sense of effort). Het moment van stoppen wordt hier gedefinieerd als uitputting of exhaustion. Met spieren worden hier de dwarsgestreepte skeletspieren bedoeld. Verband tussen geleverd vermogen en zuurstofopname voor een willekeurige proefpersoon op een fietsergometer
Pfl�gers Archiv European Journal of Physiology, 1998
The applicability of H 2 15 O-positron emission tomographic (PET) imaging for the assessment of s... more The applicability of H 2 15 O-positron emission tomographic (PET) imaging for the assessment of skeletal muscle perfusion during exercise was investigated in five healthy subjects performing intermittent isometric contractions on a calf ergometer. The workload of the left calf muscles was kept constant in all exercises, while that of the right calf muscles was varied. During exercise H 2 15 O distribution in the calf muscles was measured by PET. Radioactivity measured in the left calf muscles was used as a reference for the radioactivity measured in the right calf muscles. In all studies, muscles were delineated by uptake of radioactivity. Four subjects demonstrated high radioactivity in the gastrocnemius medialis muscle, in one subject high radioactivity was distributed over the triceps surae muscles. The observed muscles demonstrated also local foci of radioactivity indicating regionally enhanced tissue perfusion. The right-left ratio of radioactivity in the active muscles increased as a function of the load. We conclude that inter-and intramuscle perfusion differences can be measured during exercise by H 2 15 O-PET imaging.
EMG median power frequency of the calf muscles was investigated during an exhausting treadmill ex... more EMG median power frequency of the calf muscles was investigated during an exhausting treadmill exercise. This exercise was an uphill run, the average endurance time was 1.5 min. Median power frequency of the calf muscles declined by more than 10% during this exercise. In addition EMG median power frequency of isometric contractions of the same muscles was measured before and in one minute intervals for 10 min after this run. Immediately after the run isometric median power frequency had declined by less than 5% for the soleus muscle, more than 10% for the gastrocnemius medialis and gastrocnemius lateralis muscles. In the 10 min following exercise the isometric median power frequency increased to pre-exercise levels. Maybe the median power frequency shift to lower frequencies during dynamic exercise can be interpreted as a sign of local muscle fatigue.
European Journal of Applied Physiology and Occupational Physiology, 1996
... 82nd Ciba Foundation Symposium (Ed-wards 1981) as a loss of ability to maintain the expected ... more ... 82nd Ciba Foundation Symposium (Ed-wards 1981) as a loss of ability to maintain the expected force or power. In a previous study, we have investigated the EMG power spectrum of the calf muscles during an extremely exhausting uphill run at a gradient of 33% (Ament et al. ...
The electromyogram (EMG) median power frequency of the vastus lateralis and flexor digitorum supe... more The electromyogram (EMG) median power frequency of the vastus lateralis and flexor digitorum superficialis muscles was measured in 12 subjects during cycle ergometry with step-wise increasing exercise intensities up to 100% of V O 2max. Blood lactate concentration was measured to investigate the relationship between changes in lactate concentration and shifts in the EMG median power frequency of exercising vastus lateralis and non-exercising flexor digitorum superficialis muscles. The results indicated that lactate concentration did not systematically affect median frequency: in spite of a considerable increase in blood lactate concentration, no systematic decrease of the median frequency during exercise was found, either for the vastus lateralis or for the flexor digitorum superficialis muscles. Instead of a decrease of the median frequency during exercise, as seen in isometrical protocols, an increase was seen in most subjects. An interesting finding was a decrease of the median frequency of vastus lateralis muscle during recovery in 8 subjects. The present findings showed that the relationship between EMG frequency decrease, lactate accumulation and fatigue, as observed in isometric protocols, cannot be simply applied to dynamic exercise.
Tracheostoma valves are used to make hand-free speaking possible for persons who have undergone a... more Tracheostoma valves are used to make hand-free speaking possible for persons who have undergone a laryngectomy. To design and test a new tracheostoma valve to improve existing tracheostoma valves. The tracheostoma valve closes by means of strong inhalation so that all the air that is exhaled is available for phonation. The device automatically stays in the “speak-position” until the patient deliberately changes the device to the “breathing position” by a fast expiration. If all the air that has been exhaled has been consumed during phonation, the patient can inhale again, without changing the device, because a small valve automatically opens, thus allowing phonation without time limits. An experimental setup with a computer-based acquisition program was used to measure the pressure at which the valve opened and the flow at which the valve closed. The pressure and flow needed to open and close the magnetic adjustable valve were measured for different positions and contained in the co...
A treadmill with four force transducers was used to analyze gait during running. 39 volunteers ra... more A treadmill with four force transducers was used to analyze gait during running. 39 volunteers ran on a treadmill until they were exhausted. The step parameter variances showed a very distinct change in time. 17 subjects showed a sudden increase in variance. The other 22 subjects did not show such an effect, probably because they stopped too soon. This was confirmed by lactate measurements. In conclusion, the described treadmill is able to register continuously the running pattern of healthy volunteers. During an exhausting exercise, the running pattern becomes irregular in the last phase of the exercise.
It is known that the concentrations of ammonia and lactate in blood increase during incremental e... more It is known that the concentrations of ammonia and lactate in blood increase during incremental exercise. Sweat also contains lactate and ammonia. The aim of the present study was to investigate the physiological response of lactate and ammonia in plasma and sweat during a stepwise incremental cycle ergometer exercise test in ten subjects. During this test lactate and ammonia were measured in blood obtained from the earlobe and in sweat collected in a bag attached to the back of the subject. At the end of each interval this bag was emptied for measuring lactate and ammonia. A disproportional increase in the concentration of lactate and ammonia in blood was found, in sweat a disproportional decrease. The lactate concentrations in sweat were higher than those in blood. We hypothesise that lactate in sweat is produced from glycogen granules of the clear cell of the eccrine gland. This lactate production results in acidification of sweat, which facilitates the diffusion of ammonia from eccrine duct cell to duct lumen. It is uncertain how far duct cell ammonia originates from plasma, the duct cell itself might produce ammonia. Part of the ammonia in sweat could come from the breakdown of urea by skin bacteria.
The aim of this study was to investigate whether the increase of ammonia concentration and lactat... more The aim of this study was to investigate whether the increase of ammonia concentration and lactate concentration in blood was accompanied by an increased expiration of ammonia during graded exercise. Eleven healthy subjects performed an incremental cycle ergometer test. Blood ammonia, blood lactate and the amount of expired ammonia were measured until 30 minutes post exercise. The expired air was guided through a flow chamber filled with a sulphuric acid solution to trap the expired ammonia. Blood ammonia, blood lactate increased more than proportionally and the amount of expired ammonia (in micromol/min) increased exponentially with the workload. Post-exercise the amount of expired ammonia decreased within a few minutes back to pre-exercise levels while the concentrations of lactate and ammonia in blood decreased much more slowly and were still elevated after 30 minutes of recovery. We conclude that the more than proportional increase of ammonia and lactate during graded exercise, ...
Iedereen weet dat als je je lichamelijk inspant, je vroeg of laat door vermoeidheid moet stoppen.... more Iedereen weet dat als je je lichamelijk inspant, je vroeg of laat door vermoeidheid moet stoppen. Zeer zware inspanningen kunnen kort volgehouden worden. Lichte inspanningen daarentegen heel lang. In dit artikel wordt de vermoeidheid belicht. Ook wordt beschreven wat er bij inspanning zoal gemeten kan worden aan het lichaam. Bij een gegeven inspanningsintensiteit defi-nie¨ren we vermoeidheid als het gevoel dat het steeds meer moeite kost om de inspanning vol te houden (increased sense of effort). Het moment van stoppen wordt hier gedefinieerd als uitputting of exhaustion. Met spieren worden hier de dwarsgestreepte skeletspieren bedoeld. Verband tussen geleverd vermogen en zuurstofopname voor een willekeurige proefpersoon op een fietsergometer
Pfl�gers Archiv European Journal of Physiology, 1998
The applicability of H 2 15 O-positron emission tomographic (PET) imaging for the assessment of s... more The applicability of H 2 15 O-positron emission tomographic (PET) imaging for the assessment of skeletal muscle perfusion during exercise was investigated in five healthy subjects performing intermittent isometric contractions on a calf ergometer. The workload of the left calf muscles was kept constant in all exercises, while that of the right calf muscles was varied. During exercise H 2 15 O distribution in the calf muscles was measured by PET. Radioactivity measured in the left calf muscles was used as a reference for the radioactivity measured in the right calf muscles. In all studies, muscles were delineated by uptake of radioactivity. Four subjects demonstrated high radioactivity in the gastrocnemius medialis muscle, in one subject high radioactivity was distributed over the triceps surae muscles. The observed muscles demonstrated also local foci of radioactivity indicating regionally enhanced tissue perfusion. The right-left ratio of radioactivity in the active muscles increased as a function of the load. We conclude that inter-and intramuscle perfusion differences can be measured during exercise by H 2 15 O-PET imaging.
EMG median power frequency of the calf muscles was investigated during an exhausting treadmill ex... more EMG median power frequency of the calf muscles was investigated during an exhausting treadmill exercise. This exercise was an uphill run, the average endurance time was 1.5 min. Median power frequency of the calf muscles declined by more than 10% during this exercise. In addition EMG median power frequency of isometric contractions of the same muscles was measured before and in one minute intervals for 10 min after this run. Immediately after the run isometric median power frequency had declined by less than 5% for the soleus muscle, more than 10% for the gastrocnemius medialis and gastrocnemius lateralis muscles. In the 10 min following exercise the isometric median power frequency increased to pre-exercise levels. Maybe the median power frequency shift to lower frequencies during dynamic exercise can be interpreted as a sign of local muscle fatigue.
European Journal of Applied Physiology and Occupational Physiology, 1996
... 82nd Ciba Foundation Symposium (Ed-wards 1981) as a loss of ability to maintain the expected ... more ... 82nd Ciba Foundation Symposium (Ed-wards 1981) as a loss of ability to maintain the expected force or power. In a previous study, we have investigated the EMG power spectrum of the calf muscles during an extremely exhausting uphill run at a gradient of 33% (Ament et al. ...
The electromyogram (EMG) median power frequency of the vastus lateralis and flexor digitorum supe... more The electromyogram (EMG) median power frequency of the vastus lateralis and flexor digitorum superficialis muscles was measured in 12 subjects during cycle ergometry with step-wise increasing exercise intensities up to 100% of V O 2max. Blood lactate concentration was measured to investigate the relationship between changes in lactate concentration and shifts in the EMG median power frequency of exercising vastus lateralis and non-exercising flexor digitorum superficialis muscles. The results indicated that lactate concentration did not systematically affect median frequency: in spite of a considerable increase in blood lactate concentration, no systematic decrease of the median frequency during exercise was found, either for the vastus lateralis or for the flexor digitorum superficialis muscles. Instead of a decrease of the median frequency during exercise, as seen in isometrical protocols, an increase was seen in most subjects. An interesting finding was a decrease of the median frequency of vastus lateralis muscle during recovery in 8 subjects. The present findings showed that the relationship between EMG frequency decrease, lactate accumulation and fatigue, as observed in isometric protocols, cannot be simply applied to dynamic exercise.
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