The benefits that physical exercise confers on cardiovascular health are well known, whereas the ... more The benefits that physical exercise confers on cardiovascular health are well known, whereas the notion that physical exercise can also improve cognitive performance has only recently begun to be explored and has thus far yielded only controversial results. In the present study, we used a sample of young male subjects to test the effects that a single bout of aerobic exercise has on learning. Two tasks were run: the first was an orientation discrimination task involving the primary visual cortex, and the second was a simple thumb abduction motor task that relies on the primary motor cortex. Forty-four and forty volunteers participated in the first and second experiments, respectively. We found that a single bout of aerobic exercise can significantly facilitate learning mechanisms within visual and motor domains and that these positive effects can persist for at least 30 minutes following exercise. This finding suggests that physical activity, at least of moderate intensity, might promote brain plasticity. By combining physical activity–induced plasticity with specific cognitive training–induced plasticity, we favour a gradual up-regulation of a functional network due to a steady increase in synaptic strength, promoting associative Hebbian-like plasticity. How often have we heard, " Mens sana in corpore sano " , i.e., " a sound mind in a sound body " , which suggests that only a healthy body can sustain a healthy mind. Nevertheless, although this adage has been widely used for some time, its foundational notions must still be substantiated. While the benefits that physical activity confers on car-diovascular health are well known, the idea that exercise can also increase brain " performance " has only recently begun to be investigated by neuroscientists. Thus, whether and how physical exercise makes us cognitively more resourceful has been only partially explored. Several recent studies have shown that regular aerobic physical exercise might improve cognitive functions by helping functional recovery after brain injury and by preventing cognitive decline in normal ageing (for a review see 1). Moreover, many observational studies have noted good cognitive performance in subjects who report practicing regularly physical activity 2,3. Consistent with these observations, there are also structural imaging studies confirming an association between physical activity and increased grey matter volume in subjects that exercise regularly in comparison with sedentary people 4–6. Nevertheless, some of these studies have been criticized because of the presence of other direct causal links between physical activity and cognitive performance; for instance, high cognitive abilities are more likely to be associated with higher educational levels, which are, in turn, often associated with a more health-conscious life style. To overcome these problems, other studies have concentrated on the benefits of the acute effects of physical activity on cognitive processing, irrespective of the previous fitness of tested subjects. These studies compared the subjects' cognitive performance immediately before and after a single bout of aerobic exercise (for a review see 7), and some found an improvement in attention, visuospatial functions, memory, language and executive functions e.g. 2,8–11. However, many studies have reported no significant improvement in cognitive performance after physical activity, as shown in a recent review of more than 30 studies 12. Evidence from animal studies suggest that neurotrophic factors (i.e., brain-derived neurotrophic factor-BDNF) might play a key role in such effects 13,14 , and this evidence has also been confirmed in research on humans 15–17. These studies have shown a relevant and constant increase of BDNF concentration up to 60 minutes following aerobic exercise. Specific work on BDNF has shown that this factor plays a pivotal role in the induction of activity-dependent neuroplasticity 18. Thus, it can be inferred that the advantage of physical exercise may involve directly affecting synaptic plasticity by favouring the strengthening of network structures, supporting neurogenesis and favouring
Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid... more Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid changes, lasting at most 30 s; (2) a subsequent steady phase; and (3) a further dynamic phase, with a continuous decrease in heart rate (HR) and an increase in blood pressure. The interpretation was that the end of the steady phase corresponds to the physiological apnoea breaking point. This being so, during exercise apnoeas, the steady phase would be shorter, and the rate of cardiovascular changes in the subsequent unsteady phase would be faster than at rest. To test these hypotheses, we measured beat-by-beat systolic (SBP), diastolic, and mean blood pressures (MBP), HR, and stroke volume (SV) in six divers during dry resting (duration 239.4 ± 51.6 s) and exercise (30 W on cycle ergometer, duration 88.2 ± 20.9 s) maximal apnoeas, and we computed cardiac output ([Formula: see text]) and total peripheral resistance (TPR). Compared to control, at the beginning of resting (R1) and exercising (E1) apnoeas, SBP and MBP decreased and HR increased. SV and [Formula: see text] fell, so that TPR remained unchanged. At rest, HR, SV, [Formula: see text], and SBP were stable during the subsequent phase; this steady phase was missing in exercise apnoeas. Subsequently, at rest (R3) and at exercise (E2), HR decreased and SBP increased continuously. SV returned to control values. Since [Formula: see text] remained unchanged, TPR grew. The lack of steady phase during exercise apnoeas suggests that the conditions determining R3 were already attained at the end of E1. This being so, E2 would correspond to R3.
European Journal of Applied Physiology and Occupational Physiology, 1992
Oxygen uptake (VO2) at steady state, heart rate and perceived exertion were determined on nine su... more Oxygen uptake (VO2) at steady state, heart rate and perceived exertion were determined on nine subjects (six men and three women) while walking (3-7 km.h-1) or running (7-14 km.h-1) on sand or on a firm surface. The women performed the walking tests only. The energy cost of locomotion per unit of distance (C) was then calculated from the ratio of VO2 to speed and expressed in J.kg-1.m-1 assuming an energy equivalent of 20.9 J.ml O2-1. At the highest speeds C was adjusted for the measured lactate contribution (which ranged from approximately 2% to approximately 11% of the total). It was found that, when walking on sand, C increased linearly with speed from 3.1 J.kg-1.m-1 at 3 km.h-1 to 5.5 J.kg-1.m-1 at 7 km.h-1, whereas on a firm surface C attained a minimum of 2.3 J.kg-1.m-1 at 4.5 km.h-1 being greater at lower or higher speeds. On average, when walking at speeds greater than 3 km.h-1, C was about 1.8 times greater on sand than on compact terrain. When running on sand C was approximately independent of the speed, amounting to 5.3 J.kg-1.m-1, i.e. about 1.2 times greater than on compact terrain. These findings could be attributed to a reduced recovery of potential and kinetic energy at each stride when walking on sand (approximately 45% to be compared to approximately 65% on a firm surface) and to a reduced recovery of elastic energy when running on sand.
The sound (SMG) generated by the biceps muscle during isometric exercise at 20, 40, 60, and 80% o... more The sound (SMG) generated by the biceps muscle during isometric exercise at 20, 40, 60, and 80% of maximum voluntary contraction (MVC) up to exhaustion has been recorded by a contact transducer and integrated (iSMG), together with the surface electromyogram (EMG) in eight young untrained men. At the onset of exercise, iSMG and integrated surface EMG (iEMG) amplitude increased linearly with exercise. iSMG remained constant for 253 +/- 73 (SD), 45 +/- 16, 21 +/- 5, and 0 s at the four levels of contraction. Then iSMG increased linearly at 20% MVC, fluctuated at 40% MVC, and decreased exponentially at 60 and 80% MVC. iSMG exhaustion-to-onset ratio was 5.0 at 20%, 1.0 at 40%, and 0.2 at 60 and 80% MVC. On the contrary, independently of exercise intensity, iEMG increased with time, being 1.4 higher at exhaustion than at the onset. The nonunivocal iSMG changes with time and effort of exercise suggest that the sound may be a useful tool to acquire different information to EMG and output force during muscle contraction up to fatigue.
International Journal of Bio-Medical Computing, 1988
The activated muscle generates a low frequency rumbling noise, which is known as the Sound-MyoGra... more The activated muscle generates a low frequency rumbling noise, which is known as the Sound-MyoGram (SMG). Spectral analysis of the SMG is carried out in this work, in order to: (i) check the adequacy of both the Fast Fourier Transform (FFT) and the Maximum Entropy Spectrum Estimation (MESE). Because it is a well known technique, the FFT method is only briefly described, while the philosophy of the MESE method is given in more detail and completed with a description of the recursive algorithm; (ii) select a frequency parameter suitable to describe the SMG. For this purpose two well-defined physiological conditions (20% and 80% Maximal Voluntary Contraction) have been adopted in order to provide a safe reference for the interpretation of the findings. The results show that: (a) both FFT and MESE are adequate to estimate the SMG Power Spectrum; (b) both the mean and the median frequency are suitable parameters, the mean frequency being the more favourable one; (c) the SMG Power Spectrum is a promising tool to study the muscle activation modalities.
Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid... more Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid changes, lasting at most 30 s; (2) a subsequent steady phase; and (3) a further dynamic phase, with a continuous decrease in heart rate (HR) and an increase in blood pressure. The interpretation was that the end of the steady phase corresponds to the physiological apnoea breaking point. This being so, during exercise apnoeas, the steady phase would be shorter, and the rate of cardiovascular changes in the subsequent unsteady phase would be faster than at rest. To test these hypotheses, we measured beat-by-beat systolic (SBP), diastolic, and mean blood pressures (MBP), HR, and stroke volume (SV) in six divers during dry resting (duration 239.4 ± 51.6 s) and exercise (30 W on cycle ergometer, duration 88.2 ± 20.9 s) maximal apnoeas, and we computed cardiac output ([Formula: see text]) and total peripheral resistance (TPR). Compared to control, at the beginning of resting (R1) and exercising (E1) apnoeas, SBP and MBP decreased and HR increased. SV and [Formula: see text] fell, so that TPR remained unchanged. At rest, HR, SV, [Formula: see text], and SBP were stable during the subsequent phase; this steady phase was missing in exercise apnoeas. Subsequently, at rest (R3) and at exercise (E2), HR decreased and SBP increased continuously. SV returned to control values. Since [Formula: see text] remained unchanged, TPR grew. The lack of steady phase during exercise apnoeas suggests that the conditions determining R3 were already attained at the end of E1. This being so, E2 would correspond to R3.
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society, 1989
... TIME AND FREQUENCY DOMAIN ANALYSIS Claudio Orizio, Renza Perini, Arsenio Veicsteinas ... This... more ... TIME AND FREQUENCY DOMAIN ANALYSIS Claudio Orizio, Renza Perini, Arsenio Veicsteinas ... This confirms that by the SMG analysis the mean MUS firing frequency is retrivable by a non invasive methods. REFERENCES 1) Gordon G, Holbourn AHS J Physiol 1948, 107: ...
The power-spectral analysis of heart-rate variability (HRV) is used to compare situations of diff... more The power-spectral analysis of heart-rate variability (HRV) is used to compare situations of different muscular exercise in nine sedentary males (n=9) and eight professional cyclists. The changes of low-frequency (LF) and high-frequency (HF) spectral peaks, together with the weight of the very low frequencies (VLF), are described. Their relationship to changes in autonomic activation is discussed. The importance of the
The effects of an intense 8-wk aerobic training program on cardiovascular responses at rest and d... more The effects of an intense 8-wk aerobic training program on cardiovascular responses at rest and during exercise, including heart rate variability (HRV) as an expression of autonomic modulation, were evaluated in subjects over 70 yr (mean: 73.9 +/- 3.5 yr). Before and after training in 7 men and 8 women: a) heart rate (HR), blood pressures (BPs), pulse pressure (PP), and oxygen uptake were measured at rest, during, and after exhausting incremental exercise; b) HRV power spectra were calculated at rest in supine and sitting, and during and after two submaximal constant loads (5 min). Power in low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, >0.15 Hz) bands were expressed as a percent of total power minus power < 0.04 Hz. After training: a) at rest HR and HRV parameters (in both body positions) were unchanged, whereas BPs decreased; b) peak cycle resistance and oxygen consumption increased by 25% and 18%, respectively, but no change in maximal HR and BPs were found; c) during submaximal loads HR was unchanged at the same metabolic demand, whereas SBP and DBP were lower than before at low loads whereas PP was unchanged. LF power decreased and HF increased at oxygen uptakes above about 0.7 L.min-1 similarly before and after training; and d) recovery of all parameters was similar to pretraining and complete after 10 min The increase in exercise capacity without changes in cardiovascular parameters suggests that 8 wk of aerobic training augmented peripheral gas exchange but not delivery to muscle. The lack of effect on HRV indicates that the improvements in aerobic power and cardiac autonomic modulation, at least in subjects over 70 yr, are dissociated. Moreover, the metabolic demand seems to be the main factor for the changes in HRV power spectra that occur during exercise.
European Journal of Applied Physiology and Occupational Physiology, 1989
The contracting muscle generates a low frequency sound detectable at the belly surface, ranging f... more The contracting muscle generates a low frequency sound detectable at the belly surface, ranging from 11 to 40 Hz. To study the relationship between the muscular sound and the intensity of the contraction a sound myogram (SMG) was recorded by a contact sensor from the biceps brachii of seven young healthy males performing 4-s isometric contractions from 10% to 100% of the maximal voluntary contraction (MVC), in 10% steps. Simultaneously, the electromyogram (EMG) was recorded as an index of muscle activity. SMG and EMG were integrated by conventional methods (iSMG and iEMG). The relationship between iSMG and iEMG vs MVC% is described by parabolic functions up to 80% and 100% MVC respectively. Beyond 80% MVC the iSMG decreases, being about half of its maximal value at 100% MVC. Our results indicate that the motor unit recruitment and firing rate affect the iSMG and iEMG in the same way up to 80% MVC. From 80% to 100% MVC the high motor units' discharge rate and the muscular stiffness together limit the pressure waves generated by the dimensional changes of the active fibres. The muscular sound seems to reflect the intramuscular visco-elastic characteristics and the motor unit activation pattern of a contracting muscle.
European Journal of Applied Physiology and Occupational Physiology, 1989
The time course of heart rate (HR) and venous blood norepinephrine concentration [NE], as an expr... more The time course of heart rate (HR) and venous blood norepinephrine concentration [NE], as an expression of the sympathetic nervous activity (SNA), was studied in six sedentary young men during recovery from three periods of cycle ergometer exercise at 21% +/- 2.8%, 43% +/- 2.1% and 65% +/- 2.3% of VO2max respectively (mean +/- SE). The HR decreased mono-exponentially with tau values of 13.6 +/- 1.6 s, 32.7 +/- 5.6 s and 55.8 +/- 8.1 s respectively in the three periods of exercise. At the low exercise level no change in [NE] was found. At medium and high exercise intensity: (a) [NE] increased significantly at the 5th min of exercise (delta [NE] = 207.7 +/- 22.5 pg.ml-1 and 521.3 +/- 58.3 pg.ml-1 respectively); (b) after a time lag of 1 min [NE] decreased exponentially (tau = 87 s and 101 s respectively); (c) in the 1st min HR decreased about 35 beats.min-1; (d) from the 2nd to 5th min of recovery HR and [NE] were linearly related (100 pg.ml-1 delta [NE] congruent to 5 beats.min-1). In the 1st min of recovery, independent of the exercise intensity, the adjustment of HR appears to have been due mainly to the prompt restoration of vagal tone. The further decrease in HR toward the resting value could then be attributed to the return of SNA to the pre-exercise level.
The benefits that physical exercise confers on cardiovascular health are well known, whereas the ... more The benefits that physical exercise confers on cardiovascular health are well known, whereas the notion that physical exercise can also improve cognitive performance has only recently begun to be explored and has thus far yielded only controversial results. In the present study, we used a sample of young male subjects to test the effects that a single bout of aerobic exercise has on learning. Two tasks were run: the first was an orientation discrimination task involving the primary visual cortex, and the second was a simple thumb abduction motor task that relies on the primary motor cortex. Forty-four and forty volunteers participated in the first and second experiments, respectively. We found that a single bout of aerobic exercise can significantly facilitate learning mechanisms within visual and motor domains and that these positive effects can persist for at least 30 minutes following exercise. This finding suggests that physical activity, at least of moderate intensity, might promote brain plasticity. By combining physical activity–induced plasticity with specific cognitive training–induced plasticity, we favour a gradual up-regulation of a functional network due to a steady increase in synaptic strength, promoting associative Hebbian-like plasticity. How often have we heard, " Mens sana in corpore sano " , i.e., " a sound mind in a sound body " , which suggests that only a healthy body can sustain a healthy mind. Nevertheless, although this adage has been widely used for some time, its foundational notions must still be substantiated. While the benefits that physical activity confers on car-diovascular health are well known, the idea that exercise can also increase brain " performance " has only recently begun to be investigated by neuroscientists. Thus, whether and how physical exercise makes us cognitively more resourceful has been only partially explored. Several recent studies have shown that regular aerobic physical exercise might improve cognitive functions by helping functional recovery after brain injury and by preventing cognitive decline in normal ageing (for a review see 1). Moreover, many observational studies have noted good cognitive performance in subjects who report practicing regularly physical activity 2,3. Consistent with these observations, there are also structural imaging studies confirming an association between physical activity and increased grey matter volume in subjects that exercise regularly in comparison with sedentary people 4–6. Nevertheless, some of these studies have been criticized because of the presence of other direct causal links between physical activity and cognitive performance; for instance, high cognitive abilities are more likely to be associated with higher educational levels, which are, in turn, often associated with a more health-conscious life style. To overcome these problems, other studies have concentrated on the benefits of the acute effects of physical activity on cognitive processing, irrespective of the previous fitness of tested subjects. These studies compared the subjects' cognitive performance immediately before and after a single bout of aerobic exercise (for a review see 7), and some found an improvement in attention, visuospatial functions, memory, language and executive functions e.g. 2,8–11. However, many studies have reported no significant improvement in cognitive performance after physical activity, as shown in a recent review of more than 30 studies 12. Evidence from animal studies suggest that neurotrophic factors (i.e., brain-derived neurotrophic factor-BDNF) might play a key role in such effects 13,14 , and this evidence has also been confirmed in research on humans 15–17. These studies have shown a relevant and constant increase of BDNF concentration up to 60 minutes following aerobic exercise. Specific work on BDNF has shown that this factor plays a pivotal role in the induction of activity-dependent neuroplasticity 18. Thus, it can be inferred that the advantage of physical exercise may involve directly affecting synaptic plasticity by favouring the strengthening of network structures, supporting neurogenesis and favouring
Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid... more Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid changes, lasting at most 30 s; (2) a subsequent steady phase; and (3) a further dynamic phase, with a continuous decrease in heart rate (HR) and an increase in blood pressure. The interpretation was that the end of the steady phase corresponds to the physiological apnoea breaking point. This being so, during exercise apnoeas, the steady phase would be shorter, and the rate of cardiovascular changes in the subsequent unsteady phase would be faster than at rest. To test these hypotheses, we measured beat-by-beat systolic (SBP), diastolic, and mean blood pressures (MBP), HR, and stroke volume (SV) in six divers during dry resting (duration 239.4 ± 51.6 s) and exercise (30 W on cycle ergometer, duration 88.2 ± 20.9 s) maximal apnoeas, and we computed cardiac output ([Formula: see text]) and total peripheral resistance (TPR). Compared to control, at the beginning of resting (R1) and exercising (E1) apnoeas, SBP and MBP decreased and HR increased. SV and [Formula: see text] fell, so that TPR remained unchanged. At rest, HR, SV, [Formula: see text], and SBP were stable during the subsequent phase; this steady phase was missing in exercise apnoeas. Subsequently, at rest (R3) and at exercise (E2), HR decreased and SBP increased continuously. SV returned to control values. Since [Formula: see text] remained unchanged, TPR grew. The lack of steady phase during exercise apnoeas suggests that the conditions determining R3 were already attained at the end of E1. This being so, E2 would correspond to R3.
European Journal of Applied Physiology and Occupational Physiology, 1992
Oxygen uptake (VO2) at steady state, heart rate and perceived exertion were determined on nine su... more Oxygen uptake (VO2) at steady state, heart rate and perceived exertion were determined on nine subjects (six men and three women) while walking (3-7 km.h-1) or running (7-14 km.h-1) on sand or on a firm surface. The women performed the walking tests only. The energy cost of locomotion per unit of distance (C) was then calculated from the ratio of VO2 to speed and expressed in J.kg-1.m-1 assuming an energy equivalent of 20.9 J.ml O2-1. At the highest speeds C was adjusted for the measured lactate contribution (which ranged from approximately 2% to approximately 11% of the total). It was found that, when walking on sand, C increased linearly with speed from 3.1 J.kg-1.m-1 at 3 km.h-1 to 5.5 J.kg-1.m-1 at 7 km.h-1, whereas on a firm surface C attained a minimum of 2.3 J.kg-1.m-1 at 4.5 km.h-1 being greater at lower or higher speeds. On average, when walking at speeds greater than 3 km.h-1, C was about 1.8 times greater on sand than on compact terrain. When running on sand C was approximately independent of the speed, amounting to 5.3 J.kg-1.m-1, i.e. about 1.2 times greater than on compact terrain. These findings could be attributed to a reduced recovery of potential and kinetic energy at each stride when walking on sand (approximately 45% to be compared to approximately 65% on a firm surface) and to a reduced recovery of elastic energy when running on sand.
The sound (SMG) generated by the biceps muscle during isometric exercise at 20, 40, 60, and 80% o... more The sound (SMG) generated by the biceps muscle during isometric exercise at 20, 40, 60, and 80% of maximum voluntary contraction (MVC) up to exhaustion has been recorded by a contact transducer and integrated (iSMG), together with the surface electromyogram (EMG) in eight young untrained men. At the onset of exercise, iSMG and integrated surface EMG (iEMG) amplitude increased linearly with exercise. iSMG remained constant for 253 +/- 73 (SD), 45 +/- 16, 21 +/- 5, and 0 s at the four levels of contraction. Then iSMG increased linearly at 20% MVC, fluctuated at 40% MVC, and decreased exponentially at 60 and 80% MVC. iSMG exhaustion-to-onset ratio was 5.0 at 20%, 1.0 at 40%, and 0.2 at 60 and 80% MVC. On the contrary, independently of exercise intensity, iEMG increased with time, being 1.4 higher at exhaustion than at the onset. The nonunivocal iSMG changes with time and effort of exercise suggest that the sound may be a useful tool to acquire different information to EMG and output force during muscle contraction up to fatigue.
International Journal of Bio-Medical Computing, 1988
The activated muscle generates a low frequency rumbling noise, which is known as the Sound-MyoGra... more The activated muscle generates a low frequency rumbling noise, which is known as the Sound-MyoGram (SMG). Spectral analysis of the SMG is carried out in this work, in order to: (i) check the adequacy of both the Fast Fourier Transform (FFT) and the Maximum Entropy Spectrum Estimation (MESE). Because it is a well known technique, the FFT method is only briefly described, while the philosophy of the MESE method is given in more detail and completed with a description of the recursive algorithm; (ii) select a frequency parameter suitable to describe the SMG. For this purpose two well-defined physiological conditions (20% and 80% Maximal Voluntary Contraction) have been adopted in order to provide a safe reference for the interpretation of the findings. The results show that: (a) both FFT and MESE are adequate to estimate the SMG Power Spectrum; (b) both the mean and the median frequency are suitable parameters, the mean frequency being the more favourable one; (c) the SMG Power Spectrum is a promising tool to study the muscle activation modalities.
Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid... more Cardiovascular responses during resting apnoea include three phases: (1) a dynamic phase of rapid changes, lasting at most 30 s; (2) a subsequent steady phase; and (3) a further dynamic phase, with a continuous decrease in heart rate (HR) and an increase in blood pressure. The interpretation was that the end of the steady phase corresponds to the physiological apnoea breaking point. This being so, during exercise apnoeas, the steady phase would be shorter, and the rate of cardiovascular changes in the subsequent unsteady phase would be faster than at rest. To test these hypotheses, we measured beat-by-beat systolic (SBP), diastolic, and mean blood pressures (MBP), HR, and stroke volume (SV) in six divers during dry resting (duration 239.4 ± 51.6 s) and exercise (30 W on cycle ergometer, duration 88.2 ± 20.9 s) maximal apnoeas, and we computed cardiac output ([Formula: see text]) and total peripheral resistance (TPR). Compared to control, at the beginning of resting (R1) and exercising (E1) apnoeas, SBP and MBP decreased and HR increased. SV and [Formula: see text] fell, so that TPR remained unchanged. At rest, HR, SV, [Formula: see text], and SBP were stable during the subsequent phase; this steady phase was missing in exercise apnoeas. Subsequently, at rest (R3) and at exercise (E2), HR decreased and SBP increased continuously. SV returned to control values. Since [Formula: see text] remained unchanged, TPR grew. The lack of steady phase during exercise apnoeas suggests that the conditions determining R3 were already attained at the end of E1. This being so, E2 would correspond to R3.
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society, 1989
... TIME AND FREQUENCY DOMAIN ANALYSIS Claudio Orizio, Renza Perini, Arsenio Veicsteinas ... This... more ... TIME AND FREQUENCY DOMAIN ANALYSIS Claudio Orizio, Renza Perini, Arsenio Veicsteinas ... This confirms that by the SMG analysis the mean MUS firing frequency is retrivable by a non invasive methods. REFERENCES 1) Gordon G, Holbourn AHS J Physiol 1948, 107: ...
The power-spectral analysis of heart-rate variability (HRV) is used to compare situations of diff... more The power-spectral analysis of heart-rate variability (HRV) is used to compare situations of different muscular exercise in nine sedentary males (n=9) and eight professional cyclists. The changes of low-frequency (LF) and high-frequency (HF) spectral peaks, together with the weight of the very low frequencies (VLF), are described. Their relationship to changes in autonomic activation is discussed. The importance of the
The effects of an intense 8-wk aerobic training program on cardiovascular responses at rest and d... more The effects of an intense 8-wk aerobic training program on cardiovascular responses at rest and during exercise, including heart rate variability (HRV) as an expression of autonomic modulation, were evaluated in subjects over 70 yr (mean: 73.9 +/- 3.5 yr). Before and after training in 7 men and 8 women: a) heart rate (HR), blood pressures (BPs), pulse pressure (PP), and oxygen uptake were measured at rest, during, and after exhausting incremental exercise; b) HRV power spectra were calculated at rest in supine and sitting, and during and after two submaximal constant loads (5 min). Power in low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, >0.15 Hz) bands were expressed as a percent of total power minus power < 0.04 Hz. After training: a) at rest HR and HRV parameters (in both body positions) were unchanged, whereas BPs decreased; b) peak cycle resistance and oxygen consumption increased by 25% and 18%, respectively, but no change in maximal HR and BPs were found; c) during submaximal loads HR was unchanged at the same metabolic demand, whereas SBP and DBP were lower than before at low loads whereas PP was unchanged. LF power decreased and HF increased at oxygen uptakes above about 0.7 L.min-1 similarly before and after training; and d) recovery of all parameters was similar to pretraining and complete after 10 min The increase in exercise capacity without changes in cardiovascular parameters suggests that 8 wk of aerobic training augmented peripheral gas exchange but not delivery to muscle. The lack of effect on HRV indicates that the improvements in aerobic power and cardiac autonomic modulation, at least in subjects over 70 yr, are dissociated. Moreover, the metabolic demand seems to be the main factor for the changes in HRV power spectra that occur during exercise.
European Journal of Applied Physiology and Occupational Physiology, 1989
The contracting muscle generates a low frequency sound detectable at the belly surface, ranging f... more The contracting muscle generates a low frequency sound detectable at the belly surface, ranging from 11 to 40 Hz. To study the relationship between the muscular sound and the intensity of the contraction a sound myogram (SMG) was recorded by a contact sensor from the biceps brachii of seven young healthy males performing 4-s isometric contractions from 10% to 100% of the maximal voluntary contraction (MVC), in 10% steps. Simultaneously, the electromyogram (EMG) was recorded as an index of muscle activity. SMG and EMG were integrated by conventional methods (iSMG and iEMG). The relationship between iSMG and iEMG vs MVC% is described by parabolic functions up to 80% and 100% MVC respectively. Beyond 80% MVC the iSMG decreases, being about half of its maximal value at 100% MVC. Our results indicate that the motor unit recruitment and firing rate affect the iSMG and iEMG in the same way up to 80% MVC. From 80% to 100% MVC the high motor units' discharge rate and the muscular stiffness together limit the pressure waves generated by the dimensional changes of the active fibres. The muscular sound seems to reflect the intramuscular visco-elastic characteristics and the motor unit activation pattern of a contracting muscle.
European Journal of Applied Physiology and Occupational Physiology, 1989
The time course of heart rate (HR) and venous blood norepinephrine concentration [NE], as an expr... more The time course of heart rate (HR) and venous blood norepinephrine concentration [NE], as an expression of the sympathetic nervous activity (SNA), was studied in six sedentary young men during recovery from three periods of cycle ergometer exercise at 21% +/- 2.8%, 43% +/- 2.1% and 65% +/- 2.3% of VO2max respectively (mean +/- SE). The HR decreased mono-exponentially with tau values of 13.6 +/- 1.6 s, 32.7 +/- 5.6 s and 55.8 +/- 8.1 s respectively in the three periods of exercise. At the low exercise level no change in [NE] was found. At medium and high exercise intensity: (a) [NE] increased significantly at the 5th min of exercise (delta [NE] = 207.7 +/- 22.5 pg.ml-1 and 521.3 +/- 58.3 pg.ml-1 respectively); (b) after a time lag of 1 min [NE] decreased exponentially (tau = 87 s and 101 s respectively); (c) in the 1st min HR decreased about 35 beats.min-1; (d) from the 2nd to 5th min of recovery HR and [NE] were linearly related (100 pg.ml-1 delta [NE] congruent to 5 beats.min-1). In the 1st min of recovery, independent of the exercise intensity, the adjustment of HR appears to have been due mainly to the prompt restoration of vagal tone. The further decrease in HR toward the resting value could then be attributed to the return of SNA to the pre-exercise level.
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