Alberto Concu - Academia.edu (original) (raw)
Papers by Alberto Concu
BioMed research international, 2014
Spinal cord injured (SCI) individuals show an altered hemodynamic response to metaboreflex activa... more Spinal cord injured (SCI) individuals show an altered hemodynamic response to metaboreflex activation due to a reduced capacity to vasoconstrict the venous and arterial vessels below the level of the lesion. Exercise training was found to enhance circulating catecholamines and to improve cardiac preload and venous tone in response to exercise in SCI subjects. Therefore, training would result in enhanced diastolic function and capacity to vasoconstrict circulation. The aim of this study was to test the hypothesis that one year of training improves hemodynamic response to metaboreflex activation in these subjects. Nine SCI individuals were enrolled and underwent a metaboreflex activation test at the beginning of the study (T0) and after one year of training (T1). Hemodynamics were assessed by impedance cardiography and echocardiography at both T0 and T1. Results show that there was an increment in cardiac output response due to metaboreflex activity at T1 as compared to T0 (545.4 ± 68...
International Journal of Sports Medicine, 2006
The aim of this study was to quantify the error associated with the assessment of oxygen uptake (... more The aim of this study was to quantify the error associated with the assessment of oxygen uptake (VO2) by heart rate (HR) monitoring in 15 athletes freely performing their training session. A laboratory-derived equation was used on the running track to calculate VO2 (VO2est) from HR. Oxygen uptake was also assessed by means of a portable gas analyzer (VO2real). Bland and Altman statistics were carried out in order to evaluate agreement between VO2real and VO2est. The excess in carbon dioxide production (CO2excess) was measured to test the hypothesis that the subject with the highest CO2excess had the highest VO2est - VO2real difference. VO 2real was on average 0.14 l x min (-1) below VO2est. The limits of agreement of this difference were between + 0.77 and - 0.48 l x min (-1). Thus, on average VO2real was overestimated by VO2est. Spearman non-parametric statistics found a significant correlation between CO2excess and VO2est - VO2real difference (R = 0.55, p = 0.031). This study demonstrates that the use of HR monitoring to assess VO2 during field training overestimates VO2real, especially when a substantial increase in CO2excess occurs. Therefore, this method should be used with care when an excessive amount of CO2 is produced as occurs in activities that involve the lactic acid anaerobic source of energy production.
Sport Sciences for Health, 2005
There is some evidence that, above anaerobic threshold (AT), the arteriovenous oxygen difference ... more There is some evidence that, above anaerobic threshold (AT), the arteriovenous oxygen difference may increase due to a reduced hemoglobin affinity for oxygen. Thus, it should be expected that above AT, the oxygen consumption to cardiac output (VO 2 /CO) relationship would become steeper compared to below AT since, if a larger amount of O 2 could be extracted from blood, a lower CO would be required for carrying the same O 2 quantity. We tested the possibility that the VO 2 /CO relationship shows a break point after AT, becoming steeper. Cardiodynamics and expired gases were measured with an impedance cardiograph and a mass spectrometer in ten healthy male subjects during an incremental test on a cycle ergometer. We performed three linear regressions for each subject's VO 2 /CO ratio: one for the entire exercise dataset, one for data below AT, and one for data above AT. Statistical com-parisons of linear regressions obtained from VO 2 and CO for below and above AT data failed to find any significant difference between these data. This study demonstrates that the slope of the VO 2 /CO relationship does not exhibit a break point at AT. Therefore, it seems that AT does not play a key role in affecting this relationship during incremental exercise.
Sport Sciences for Health, 2004
Eight healthy male subjects performed a cycle ergometer incremental exercise up to exhaustion to ... more Eight healthy male subjects performed a cycle ergometer incremental exercise up to exhaustion to study possible relationships between excess CO 2 production (CO 2-exc ) and natural killer (NK) cells, measured in terms of concentration (NK abs ) and as a percentage of lymphocytes in peripheral blood (NK%). A parabola-like regression equation with its vertex downwards best fit the relationship between CO 2-exc at W max and the difference between NK cell measurements at the maximum workload (W max ) and at the workload corresponding to the anaerobic threshold (W AT ). For NK cell concentration, the best equation was NK abs (cells/mm 3 )=248.8413-0.3105 CO 2-exc (ml min -1 )+0.0001 CO 2-exc 2 (ml min -1 ) (p=0.044). For NK cells expressed as a percentage, the best equation was NK(%)=108.7636-0.1414 CO 2-exc (ml min -1 )+0.00001 CO 2-exc 2 (ml min -1 ) (p=0.032). Thus, the higher was the CO 2-exc the lower was the increase in both NK cell measurements at W max with respect to the value observed at W AT . However, when CO 2-exc reached more elevated values, then the direction of this relationship was inverted. It may be concluded that when strenuous exercise is performed, an anti-inflammatory/performance-preserving event takes place, while recovery towards a pro-inflammatory/anti-infection state tends gradually to re-establish when a subject's anaerobic power becomes too high.
Sports Medicine, Training and Rehabilitation, 1996
Six male basketball players (18 ± 0.2 years old), all playing on the same team, performed two inc... more Six male basketball players (18 ± 0.2 years old), all playing on the same team, performed two incremental, cycle ergometer exercises while connected to an instrumental apparatus from which cardiocirculatory, respiratory, and metabolic variables were recorded. The first test (T1) was performed at the height of the game season when athletes were in full training, mainly doing strength exercises. The
Sports Medicine, Training and Rehabilitation, 1994
By means of noninvasive transthoracic impedance cardiography, the cardiovascular profile of two g... more By means of noninvasive transthoracic impedance cardiography, the cardiovascular profile of two groups of male asymptomatic and glycometabolic‐compensated insulin‐dependent diabetics (IDD), one composed of five untrained patients (UD) and the other of five athletes trained for aerobic‐anaerobic sports (TD), was studied during a cycle ergometer progressive exercise up to a submaximal work rate corresponding to a heart rate (HR) of 130 beats/ min (W 130). At rest, although HR and arterial blood pressure were similar in the two groups, values for TD were higher than for UD in stroke volume (SI, +14%) and cardiac output (CI, +26%) index expressed per m of body surface area, impedance‐derived cardiac work indicator (CWI, +24%), impedance‐derived heart mechanical efficiency indicator (HEI, +16%), impedance‐derived ventricle preload indicator (PLI, +12%), and those for TD were lower than for UD in impedance‐derived total peripheral resistance indicator (TPRI, ‐24%) and impedance‐derived myocardial contractility indicator (MCI, ‐25%). With respect to rest, at W 130 TD showed the following changes: SI, +9%; CI, +82%; CWI, +122%; HEI, ‐3%; PLI, +5%; TPRI, ‐65%; and MCI, +27%. UD showed: SI, ‐6%; CI, +59%; CWI, +82%; HEI, ‐20%; PLI, ‐3%; TPRI, ‐29%; and MCI, ‐5%. It was concluded that in the asymptomatic IDD patient a sedentary habit may lead to subclinical left ventricle dysfunction. On the contrary, participation in competitive sports led to an increase in the physical capacity of the subjects and also reduced the risk of cardiomyopathy.
Sports Medicine, Training and Rehabilitation, 2001
Phono‐mechano‐cardiography (PMC) methodology for measuring such systolic time intervals (STI) as ... more Phono‐mechano‐cardiography (PMC) methodology for measuring such systolic time intervals (STI) as the pre‐ejection period (PEP), ventricular ejection time (VET) and the ratio (PEP/VET) is not an adequate method when STI are evaluated in an exercising subject (e.g. stress testing, functional capacity etc.). This is due to the complexity of positioning and keeping PMC transducers at the recording site secure while
Physiological Measurement, 2006
To date, few attempts have been made to correlate cardiovascular variables to lactate threshold (... more To date, few attempts have been made to correlate cardiovascular variables to lactate threshold (L(T)). This study was designed to determine the relationship between the accumulation of blood lactate and several haemodynamic variables during exercise. Eight male volunteer cyclists performed an incremental test on an electromagnetically braked cycle-ergometer consisting of a 50 W linear increase in workload every 3 min up to exhaustion. Blood lactate was measured with a portable analyser during each exercise step. Oxygen consumption (VO(2)) and pulmonary ventilation were measured by means of a mass spectrometer while heart rate, stroke volume and cardiac output (CO) were assessed by impedance cardiography. The arterio-venous oxygen difference (A-V O(2) Diff) was obtained by dividing VO(2) by CO. By applying the D(max) mathematical method, L(T) and thresholds of ventilatory and haemodynamic parameters were calculated. The Bland and Altman statistics used to assess agreement between two methods of measurement were applied in order to evaluate the agreement between L(T) and thresholds derived from ventilatory and haemodynamic data. The main result was that most of the haemodynamic variables did not provide thresholds which could be used interchangeably with L(T). Only the threshold of A-V O(2) Diff showed mean values that were no different compared to L(T) together with limits of agreement that were not very wide between thresholds (below +/-25%). Hence of the haemodynamic parameters, A-V O(2) Diff appears to be the one most closely coupled with lactate accumulation and consequently it is also the most suitable for non-invasive calculation of the L(T).
Physiological Measurement, 2007
This investigation aimed at verifying whether it was possible to reliably assess stroke volume (S... more This investigation aimed at verifying whether it was possible to reliably assess stroke volume (SV) during exercise from oxygen pulse (OP) and from a model of arterio-venous oxygen difference (a-vO(2)D) estimation. The model was tested in 15 amateur male cyclists performing an exercise test on a cycle-ergometer consisting of a linear increase of workload up to exhaustion. Starting from the analysis of previous published data, we constructed a model of a-vO(2)D estimation (a-vO(2)D(est)) which predicted that the a-vO(2)D at rest was 30% of the total arterial O(2) content (CaO(2)) and that it increased linearly during exercise reaching a value of 80% of CaO(2) at the peak workload (W(max)) of cycle exercise. Then, the SV was calculated by applying the following equation, SV = OP/a-vO(2)D(est), where the OP was assessed as the oxygen uptake/heart rate. Data calculated by our model were compared with those obtained by impedance cardiography. The main result was that the limits of agreement between the SV assessed by impedance cardiography and the SV estimated were between 22.4 and -27.9 ml (+18.8 and -24% in terms of per cent difference between the two SV measures). It was concluded that our model for estimating SV during effort may be reasonably applicable, at least in a healthy population.
Pfl�gers Archiv European Journal of Physiology, 1983
Experiments were carried out on cats to re-examine the respiratory effects of the stimulation of ... more Experiments were carried out on cats to re-examine the respiratory effects of the stimulation of the large afferent fibers originating in the receptors of the hindlimb muscles. During the contraction of the triceps surae induced by stimulating the ventral roots, pulmonary ventilation increased due to an increase in tidal volume and, usually, in respiratory frequency. An increase in ventilation occurred also during stimulation at group I strength of the central end of the previously cut nerves to the triceps surae (LGS + MG) and to the posterior biceps plus the semitendinosus (PBST) muscles. Appreciable increase in ventilation was seen for stimuli near threshold for group I (Ia + I b) afferent fibers of the LGS + MG nerves, while stimuli at group I b strength were needed to produce the same effects when using the PBST nerves. It is concluded that group Ib fibers afferent from muscle receptors play a role in the reflex control of respiration.
Pfl�gers Archiv European Journal of Physiology, 1984
Increments in pulmonary ventilation were shown to occur in anaesthetized cats during long-lasting... more Increments in pulmonary ventilation were shown to occur in anaesthetized cats during long-lasting stimulation of a peripherally cut extensor muscle nerve at maximal intensity for group I afferent fibers. However, these increments tended to gradually adapt to a lower value when stimuli were delivered at high frequency and constant rate whereas a tendency to potentiation, up to a steady state, occurred when stimulation was intermittent. End-tidal Pco2 initially decreased with a tendency to adaptation in the case of continuous stimulation, and decreased progressively in the case of intermittent stimulation. It is concluded that the nervous mechanisms producing hyperpnoea exhibit fatigue during their constant excitation while their effects sum up during intermittent stimulation.
Medicine & Science in Sports & Exercise, 2003
One of the primary neural mechanisms responsible for the cardiovascular adjustments to exercise i... more One of the primary neural mechanisms responsible for the cardiovascular adjustments to exercise is the "exercise pressor reflex"; a reflex arising from activation of chemically and mechanically sensitive afferents in contracting skeletal muscle (4). Numerous human investigations have indicated that the chemically sensitive component of the reflex, termed the muscle metaboreflex, is primarily responsible for exercise-induced sympathoexcitation, which leads to increases in systemic vascular resistance (SVR) and subsequent elevations in blood pressure. These findings have mainly been derived from studies in which static exercise was performed followed by post exercise ischemia (PEI). The latter maneuver traps the metabolic products of contraction in the vicinity of the metaboreceptor afferent endings while eliminating inputs from mechanically sensitive afferents and central command, the central neural drive associated with the volitional component of exercise. During isolation of the metaboreflex with PEI, heart rate has been shown to return to baseline and limited work has demonstrated that stroke volume (SV) is similar to resting values indicating little affect of the metaboreflex on cardiac output (2). In contrast, animal studies have shown that alterations in cardiac output contribute importantly to metaboreflex-mediated increases in blood pressure (1). Whether these differences are solely due to a species related functional variation remains unclear.
Medicine & Science in Sports & Exercise, 2000
Hemodynamic events leading to spontaneous postexertional vasovagal syncope are not completely und... more Hemodynamic events leading to spontaneous postexertional vasovagal syncope are not completely understood because of the lack of beat-to-beat data. We report a case study of a young athlete who undergoes a syncopal episode during the recovery period following a maximal cycle-ergometer test. The episode was monitored by an impedance cardiograph which can gather noninvasively beat-to-beat the flow of heart rate (HR), stroke volume (SV), cardiac output (CO), diastolic filling rate (SV/DT), and myocardial contractility index (PEP/LVET). The most important findings of this report are the dramatic reduction of SV/DT preceding the syncope, the increment of SV together with the reduction of HR preceding and following the syncope, the prompt recovery of CO values after the syncopal episode despite the bradycardia, and the reduction of PEP/LVET after the syncope. This report confirms the importance of active recovery immediately after strenuous exercise and supports the hypothesis that the reduction of SV/DT in the presence of an inotropic stimulation can trigger the vasovagal reaction.
Journal of Sports Sciences, 2007
Nitroglycerin induces the so-called second window of protection (SWOP), which alleviates myocardi... more Nitroglycerin induces the so-called second window of protection (SWOP), which alleviates myocardial damage and stunning after ischaemia/reperfusion. To determine whether myocardial performance during exercise is improved in the second window of protection, we studied the haemodynamic responses of 12 trained and 11 sedentary individuals during a sequence of maximal tests on a cycle ergometer. A baseline test (basal test) was followed by a second effort performed during the second window of protection (exercise-SWOP test). Haemodynamics was also evaluated after pharmacologically induced SWOP 48 h after transdermal administration of 10 mg of nitroglycerin (pharmacologically induced SWOP test). The exercise-SWOP and pharmacologically induced SWOP tests were separated by a 1-week washout period. Endothelial-dependent vasodilatation after nitroglycerin pre-treatment was also assessed in five sedentary individuals to determine whether nitrate donors could affect vascular function. We found that nitroglycerin pre-treatment did not induce any improvement in haemodynamics in either trained or sedentary individuals, since maximum values of workload, heart rate, stroke volume, cardiac output, myocardial contractility, and double product were similar between the exercise-SWOP and pharmacologically induced SWOP tests in both groups. Furthermore, nitroglycerin pre-treatment did not alter flow-mediated dilation during pharmacologically induced SWOP. Although nitroglycerin pre-treatment alleviates post-ischaemic myocardial stunning, our results suggest that it does not affect the myocardial performance of healthy individuals during exercise performed in the second window of protection, independently of the training status of the individuals. Moreover, nitroglycerin pre-treatment does not ameliorate endothelial function.
Journal of Sports Sciences, 2007
Spinning is a type of indoor fitness activity performed on stationary bikes by participants who p... more Spinning is a type of indoor fitness activity performed on stationary bikes by participants who pedal together to the rhythm of music and the motivating words of an instructor. Despite worldwide popularity of this type of recreational activity, to date there have been few, mainly non-scientific, studies of the impact of spinning on metabolic, respiratory, and cardiovascular functions. The main aim of this study was to evaluate a number of metabolic and cardiovascular variables during a standard 50-min class performed by Spinning instructors of both sexes: six males (age 30 +/- 4.8 years, body mass index 24 +/- 2.5 kg x m(-2); mean +/- s) and six females (age 34 +/- 6.3 years, body mass index 21 +/- 1.9 kg x m(-2)). The mean power output, heart rate, and oxygen uptake during the performance were 120 +/- 4 W, 136 +/- 13 beats x min(-1), and 32.8 +/- 5.4 ml x kg(-1) x min(-1) respectively for males, and 73 +/- 43 W, 143 +/- 25 beats x min(-1), and 30 +/- 9.9 ml x kg(-1) x min(-1) respectively for females. Analysis of individual performances showed that they were compatible with physical exercise that ranged from moderate-to-heavy to very heavy, the latter conditions prevailing. The results show that this type of fitness activity has a high impact on cardiovascular function and suggest that it is not suitable for unfit or sedentary individuals, especially the middle aged or elderly, who are willing to begin a recreational physical activity programme.
Journal of Physics: Conference Series, 2012
ABSTRACT Data concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dyna... more ABSTRACT Data concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dynamic apnoea (DA) were collected from 10 healthy male, elite divers by means of an impedance cardiograph adapted to the underwater environment (C. O. Re., from 2C Technologies Inc, Italy). Three trials were performed by the divers in a 3-m-deep pool with a water temperature of 25°C: 3-minute head-out immersion during normal breathing (A), till exhaustion immersed at the surface (B) and at 3m depth (C). Both B and C conditions did not led to changes in HR, SV and CO compared to A. Data indicate that typical diving response consisting in a reduction of HR, SV and CO was not present during DA, probably due to sympathetic activation induced by exercise during DA, which partially obscured the effects of the diving response. Moreover, this study highlights the innovative role of our portable, impedance cardiography device, i.e. the C. O. Re., in easily assessing cardiodynamic changes in subjects engaged in exercise schedules including phases of underwater, dynamic apnoea.
Journal of Allergy and Clinical Immunology, 2003
The visual analog scale (VAS) is a valid and reliable assessment of pain in clinical studies and ... more The visual analog scale (VAS) is a valid and reliable assessment of pain in clinical studies and has also been used to assess drowsiness associated with antihistamine use. However, no analysis has been undertaken to assess the reliability and reproducibility of VAS in measuring drowsiness and motivation.
Experimental Physiology, 2004
We aimed to investigate haemodynamics during active and passive recovery following repeated bouts... more We aimed to investigate haemodynamics during active and passive recovery following repeated bouts of supramaximal exercise. Seven male athletes underwent two sessions of supramaximal exercise which consisted of a warm-up and of five bouts of cycling at the maximum speed possible for 30 s against a resistance equivalent to 150% of the maximum workload achieved in a previous incremental test. Bouts were separated by 1 min of recovery and followed by 10 min of recovery which was either active (pedalling at 40 W) or passive (completely rest seated on the cycle). Haemodynamic variables were evaluated by means of impedance cardiography. Heart rate (HR), stroke volume (SV), cardiac output (CO), mean blood pressure (MBP), thoracic electrical impedance (Z 0 ) as an inverse index of central blood volume, and systemic vascular resistance (SVR) were assessed. The main findings were that active recovery, with respect to passive recovery, induced higher changes from baseline in HR (+29.1 ± 4.5 versus +15.6 ± 2.9 beats min −1 at the 10th minute of recovery, P < 0.05), SV (+19.9 ± 5.6 versus -6.4 ± 3.3 ml, P < 0.01) and CO (+3.8 ± 1.2 versus +0.4 ± 0.2 l min −1 , P < 0.01). Furthermore, MBP was similar between the two kinds of recovery despite an increase in Z 0 during passive compared to active recovery. These results suggest that the faster haemodynamic recovery towards baseline and the decrease in cardiac preload during passive recovery may be successfully prevented by cardiovascular regulatory mechanisms which include an increase in SVR, thus avoiding a drop in blood pressure.
Experimental Physiology, 2008
Maintained exercise pressor response in heart failure. J. Appl. Physiol. 85(5): 1793-1799.-The im... more Maintained exercise pressor response in heart failure. J. Appl. Physiol. 85(5): 1793-1799.-The impact of forearm blood flow limitation on muscle reflex (metaboreflex) activation during exercise was examined in 10 heart failure (HF) (NYHA class III and IV) and 9 control subjects. Rhythmic handgrip contractions (25% maximal voluntary contraction, 30 contractions/min) were performed over 5 min under conditions of ambient pressure or with ϩ50 mmHg positive pressure about the exercising forearm. Mean arterial blood pressure (MAP) and venous effluent hemoglobin (Hb) O 2 saturation, lactate and H ϩ concentrations ([La] and [H ϩ ], respectively) were measured at baseline and during exercise. For ambient contractions, the increase (⌬) in MAP by end exercise (⌬MAP; i.e., the exercise pressor response) was the same in both groups (10.1 Ϯ 1.2 vs. 7.33 Ϯ 1.3 mmHg, HF vs. Ctl, respectively) despite larger ⌬[La] and ⌬[H ϩ ] for the HF group (P Ͻ 0.05). With ischemic exercise, the ⌬MAP for HF (21.7 Ϯ 2.7 mmHg) exceeded that of Ctl subjects (12.2 Ϯ 2.8 mmHg) (P Ͻ 0.0001). Also, for HF, ⌬[La] (2.94 Ϯ 0.4 mmol) and ⌬[H ϩ ] (24.8 Ϯ 2.7 nmol) in the ischemic trial were greater than in Ctl (1.63 Ϯ 0.4 mmol and 15.3 Ϯ 2.8 nmol; [La] and [H ϩ ], respectively) (P Ͻ 0.02). Hb O 2 saturation was reduced in Ctl from ϳ43% in the ambient trial to ϳ27% with ischemia (P Ͻ 0.0001). O 2 extraction was maximized under ambient exercise conditions for HF but not for Ctl. Despite progressive increases in blood perfusion pressure over the course of ischemic exercise, no improvement in Hb O 2 saturation or muscle metabolism was observed in either group. These data suggest that muscle reflex activation of the pressor response is intact in HF subjects but the resulting improvement in perfusion pressure does not appear to enhance muscle oxidative metabolism or muscle blood flow, possibly because of associated increases in sympathetic vasoconstriction of active skeletal muscle. metaboreflex; hemoglobin oxygen saturation; lactate; hydrogen ion; pH; positive pressure COMPARED WITH HEALTHY INDIVIDUALS, patients with chronic heart failure (HF) demonstrate reduced tolerance for exercise . The mechanism responsible for exercise intolerance is thought to involve reduced muscle vascular conductance (15, 44) causing an imbalance in oxygen delivery and energy requirements. However, altered muscle biochemical properties are also known to occur in human HF patients and in animal models of HF (5), resulting in greater reliance on glycolytic metabolism.
European Journal of Pharmacology, 1978
The unilateral, intranigral administration of kainic acid (k.a.) produced a syndrome characterize... more The unilateral, intranigral administration of kainic acid (k.a.) produced a syndrome characterized by early sequelae of contra- and ipsilateral circling and by a chronic contralateral turning associated with moderate loss of neurons in the pars reticulata. The acute contralateral circling seems to be related to dopaminergic nigro-neostriatal neuron stimulation, since it was prevented by previous intranigral injections of 6-OHDA. The acute ipsilateral circling and the chronic contralateral turning, on the other hand, seem to be independent of the integrity of the dopaminergic system and may be due to an initial stimulation, followed by destruction, of a nigral neuronal system which mediates turning behavior in a manner opposite to that of nigro-striatal dopamine. Treatment with D-amphetamine or apomorphine changed the contralateral into ipsilateral turning, while haloperidol potentiated the contralateral turning. Bilateral injection of k.a. into the nigra resulted in chronic stereotyped sniffing and gnawing, which were not inhibited by haloperidol. Moreover, haloperidol did not produce catalepsy in these animals. It is suggested that the intranigral k.a. injection destroyed a neuronal system antagonistic to dopamine and resulted in a reduction of the response to DA-receptor stimulation of the c. striatum.
BioMed research international, 2014
Spinal cord injured (SCI) individuals show an altered hemodynamic response to metaboreflex activa... more Spinal cord injured (SCI) individuals show an altered hemodynamic response to metaboreflex activation due to a reduced capacity to vasoconstrict the venous and arterial vessels below the level of the lesion. Exercise training was found to enhance circulating catecholamines and to improve cardiac preload and venous tone in response to exercise in SCI subjects. Therefore, training would result in enhanced diastolic function and capacity to vasoconstrict circulation. The aim of this study was to test the hypothesis that one year of training improves hemodynamic response to metaboreflex activation in these subjects. Nine SCI individuals were enrolled and underwent a metaboreflex activation test at the beginning of the study (T0) and after one year of training (T1). Hemodynamics were assessed by impedance cardiography and echocardiography at both T0 and T1. Results show that there was an increment in cardiac output response due to metaboreflex activity at T1 as compared to T0 (545.4 ± 68...
International Journal of Sports Medicine, 2006
The aim of this study was to quantify the error associated with the assessment of oxygen uptake (... more The aim of this study was to quantify the error associated with the assessment of oxygen uptake (VO2) by heart rate (HR) monitoring in 15 athletes freely performing their training session. A laboratory-derived equation was used on the running track to calculate VO2 (VO2est) from HR. Oxygen uptake was also assessed by means of a portable gas analyzer (VO2real). Bland and Altman statistics were carried out in order to evaluate agreement between VO2real and VO2est. The excess in carbon dioxide production (CO2excess) was measured to test the hypothesis that the subject with the highest CO2excess had the highest VO2est - VO2real difference. VO 2real was on average 0.14 l x min (-1) below VO2est. The limits of agreement of this difference were between + 0.77 and - 0.48 l x min (-1). Thus, on average VO2real was overestimated by VO2est. Spearman non-parametric statistics found a significant correlation between CO2excess and VO2est - VO2real difference (R = 0.55, p = 0.031). This study demonstrates that the use of HR monitoring to assess VO2 during field training overestimates VO2real, especially when a substantial increase in CO2excess occurs. Therefore, this method should be used with care when an excessive amount of CO2 is produced as occurs in activities that involve the lactic acid anaerobic source of energy production.
Sport Sciences for Health, 2005
There is some evidence that, above anaerobic threshold (AT), the arteriovenous oxygen difference ... more There is some evidence that, above anaerobic threshold (AT), the arteriovenous oxygen difference may increase due to a reduced hemoglobin affinity for oxygen. Thus, it should be expected that above AT, the oxygen consumption to cardiac output (VO 2 /CO) relationship would become steeper compared to below AT since, if a larger amount of O 2 could be extracted from blood, a lower CO would be required for carrying the same O 2 quantity. We tested the possibility that the VO 2 /CO relationship shows a break point after AT, becoming steeper. Cardiodynamics and expired gases were measured with an impedance cardiograph and a mass spectrometer in ten healthy male subjects during an incremental test on a cycle ergometer. We performed three linear regressions for each subject's VO 2 /CO ratio: one for the entire exercise dataset, one for data below AT, and one for data above AT. Statistical com-parisons of linear regressions obtained from VO 2 and CO for below and above AT data failed to find any significant difference between these data. This study demonstrates that the slope of the VO 2 /CO relationship does not exhibit a break point at AT. Therefore, it seems that AT does not play a key role in affecting this relationship during incremental exercise.
Sport Sciences for Health, 2004
Eight healthy male subjects performed a cycle ergometer incremental exercise up to exhaustion to ... more Eight healthy male subjects performed a cycle ergometer incremental exercise up to exhaustion to study possible relationships between excess CO 2 production (CO 2-exc ) and natural killer (NK) cells, measured in terms of concentration (NK abs ) and as a percentage of lymphocytes in peripheral blood (NK%). A parabola-like regression equation with its vertex downwards best fit the relationship between CO 2-exc at W max and the difference between NK cell measurements at the maximum workload (W max ) and at the workload corresponding to the anaerobic threshold (W AT ). For NK cell concentration, the best equation was NK abs (cells/mm 3 )=248.8413-0.3105 CO 2-exc (ml min -1 )+0.0001 CO 2-exc 2 (ml min -1 ) (p=0.044). For NK cells expressed as a percentage, the best equation was NK(%)=108.7636-0.1414 CO 2-exc (ml min -1 )+0.00001 CO 2-exc 2 (ml min -1 ) (p=0.032). Thus, the higher was the CO 2-exc the lower was the increase in both NK cell measurements at W max with respect to the value observed at W AT . However, when CO 2-exc reached more elevated values, then the direction of this relationship was inverted. It may be concluded that when strenuous exercise is performed, an anti-inflammatory/performance-preserving event takes place, while recovery towards a pro-inflammatory/anti-infection state tends gradually to re-establish when a subject's anaerobic power becomes too high.
Sports Medicine, Training and Rehabilitation, 1996
Six male basketball players (18 ± 0.2 years old), all playing on the same team, performed two inc... more Six male basketball players (18 ± 0.2 years old), all playing on the same team, performed two incremental, cycle ergometer exercises while connected to an instrumental apparatus from which cardiocirculatory, respiratory, and metabolic variables were recorded. The first test (T1) was performed at the height of the game season when athletes were in full training, mainly doing strength exercises. The
Sports Medicine, Training and Rehabilitation, 1994
By means of noninvasive transthoracic impedance cardiography, the cardiovascular profile of two g... more By means of noninvasive transthoracic impedance cardiography, the cardiovascular profile of two groups of male asymptomatic and glycometabolic‐compensated insulin‐dependent diabetics (IDD), one composed of five untrained patients (UD) and the other of five athletes trained for aerobic‐anaerobic sports (TD), was studied during a cycle ergometer progressive exercise up to a submaximal work rate corresponding to a heart rate (HR) of 130 beats/ min (W 130). At rest, although HR and arterial blood pressure were similar in the two groups, values for TD were higher than for UD in stroke volume (SI, +14%) and cardiac output (CI, +26%) index expressed per m of body surface area, impedance‐derived cardiac work indicator (CWI, +24%), impedance‐derived heart mechanical efficiency indicator (HEI, +16%), impedance‐derived ventricle preload indicator (PLI, +12%), and those for TD were lower than for UD in impedance‐derived total peripheral resistance indicator (TPRI, ‐24%) and impedance‐derived myocardial contractility indicator (MCI, ‐25%). With respect to rest, at W 130 TD showed the following changes: SI, +9%; CI, +82%; CWI, +122%; HEI, ‐3%; PLI, +5%; TPRI, ‐65%; and MCI, +27%. UD showed: SI, ‐6%; CI, +59%; CWI, +82%; HEI, ‐20%; PLI, ‐3%; TPRI, ‐29%; and MCI, ‐5%. It was concluded that in the asymptomatic IDD patient a sedentary habit may lead to subclinical left ventricle dysfunction. On the contrary, participation in competitive sports led to an increase in the physical capacity of the subjects and also reduced the risk of cardiomyopathy.
Sports Medicine, Training and Rehabilitation, 2001
Phono‐mechano‐cardiography (PMC) methodology for measuring such systolic time intervals (STI) as ... more Phono‐mechano‐cardiography (PMC) methodology for measuring such systolic time intervals (STI) as the pre‐ejection period (PEP), ventricular ejection time (VET) and the ratio (PEP/VET) is not an adequate method when STI are evaluated in an exercising subject (e.g. stress testing, functional capacity etc.). This is due to the complexity of positioning and keeping PMC transducers at the recording site secure while
Physiological Measurement, 2006
To date, few attempts have been made to correlate cardiovascular variables to lactate threshold (... more To date, few attempts have been made to correlate cardiovascular variables to lactate threshold (L(T)). This study was designed to determine the relationship between the accumulation of blood lactate and several haemodynamic variables during exercise. Eight male volunteer cyclists performed an incremental test on an electromagnetically braked cycle-ergometer consisting of a 50 W linear increase in workload every 3 min up to exhaustion. Blood lactate was measured with a portable analyser during each exercise step. Oxygen consumption (VO(2)) and pulmonary ventilation were measured by means of a mass spectrometer while heart rate, stroke volume and cardiac output (CO) were assessed by impedance cardiography. The arterio-venous oxygen difference (A-V O(2) Diff) was obtained by dividing VO(2) by CO. By applying the D(max) mathematical method, L(T) and thresholds of ventilatory and haemodynamic parameters were calculated. The Bland and Altman statistics used to assess agreement between two methods of measurement were applied in order to evaluate the agreement between L(T) and thresholds derived from ventilatory and haemodynamic data. The main result was that most of the haemodynamic variables did not provide thresholds which could be used interchangeably with L(T). Only the threshold of A-V O(2) Diff showed mean values that were no different compared to L(T) together with limits of agreement that were not very wide between thresholds (below +/-25%). Hence of the haemodynamic parameters, A-V O(2) Diff appears to be the one most closely coupled with lactate accumulation and consequently it is also the most suitable for non-invasive calculation of the L(T).
Physiological Measurement, 2007
This investigation aimed at verifying whether it was possible to reliably assess stroke volume (S... more This investigation aimed at verifying whether it was possible to reliably assess stroke volume (SV) during exercise from oxygen pulse (OP) and from a model of arterio-venous oxygen difference (a-vO(2)D) estimation. The model was tested in 15 amateur male cyclists performing an exercise test on a cycle-ergometer consisting of a linear increase of workload up to exhaustion. Starting from the analysis of previous published data, we constructed a model of a-vO(2)D estimation (a-vO(2)D(est)) which predicted that the a-vO(2)D at rest was 30% of the total arterial O(2) content (CaO(2)) and that it increased linearly during exercise reaching a value of 80% of CaO(2) at the peak workload (W(max)) of cycle exercise. Then, the SV was calculated by applying the following equation, SV = OP/a-vO(2)D(est), where the OP was assessed as the oxygen uptake/heart rate. Data calculated by our model were compared with those obtained by impedance cardiography. The main result was that the limits of agreement between the SV assessed by impedance cardiography and the SV estimated were between 22.4 and -27.9 ml (+18.8 and -24% in terms of per cent difference between the two SV measures). It was concluded that our model for estimating SV during effort may be reasonably applicable, at least in a healthy population.
Pfl�gers Archiv European Journal of Physiology, 1983
Experiments were carried out on cats to re-examine the respiratory effects of the stimulation of ... more Experiments were carried out on cats to re-examine the respiratory effects of the stimulation of the large afferent fibers originating in the receptors of the hindlimb muscles. During the contraction of the triceps surae induced by stimulating the ventral roots, pulmonary ventilation increased due to an increase in tidal volume and, usually, in respiratory frequency. An increase in ventilation occurred also during stimulation at group I strength of the central end of the previously cut nerves to the triceps surae (LGS + MG) and to the posterior biceps plus the semitendinosus (PBST) muscles. Appreciable increase in ventilation was seen for stimuli near threshold for group I (Ia + I b) afferent fibers of the LGS + MG nerves, while stimuli at group I b strength were needed to produce the same effects when using the PBST nerves. It is concluded that group Ib fibers afferent from muscle receptors play a role in the reflex control of respiration.
Pfl�gers Archiv European Journal of Physiology, 1984
Increments in pulmonary ventilation were shown to occur in anaesthetized cats during long-lasting... more Increments in pulmonary ventilation were shown to occur in anaesthetized cats during long-lasting stimulation of a peripherally cut extensor muscle nerve at maximal intensity for group I afferent fibers. However, these increments tended to gradually adapt to a lower value when stimuli were delivered at high frequency and constant rate whereas a tendency to potentiation, up to a steady state, occurred when stimulation was intermittent. End-tidal Pco2 initially decreased with a tendency to adaptation in the case of continuous stimulation, and decreased progressively in the case of intermittent stimulation. It is concluded that the nervous mechanisms producing hyperpnoea exhibit fatigue during their constant excitation while their effects sum up during intermittent stimulation.
Medicine & Science in Sports & Exercise, 2003
One of the primary neural mechanisms responsible for the cardiovascular adjustments to exercise i... more One of the primary neural mechanisms responsible for the cardiovascular adjustments to exercise is the "exercise pressor reflex"; a reflex arising from activation of chemically and mechanically sensitive afferents in contracting skeletal muscle (4). Numerous human investigations have indicated that the chemically sensitive component of the reflex, termed the muscle metaboreflex, is primarily responsible for exercise-induced sympathoexcitation, which leads to increases in systemic vascular resistance (SVR) and subsequent elevations in blood pressure. These findings have mainly been derived from studies in which static exercise was performed followed by post exercise ischemia (PEI). The latter maneuver traps the metabolic products of contraction in the vicinity of the metaboreceptor afferent endings while eliminating inputs from mechanically sensitive afferents and central command, the central neural drive associated with the volitional component of exercise. During isolation of the metaboreflex with PEI, heart rate has been shown to return to baseline and limited work has demonstrated that stroke volume (SV) is similar to resting values indicating little affect of the metaboreflex on cardiac output (2). In contrast, animal studies have shown that alterations in cardiac output contribute importantly to metaboreflex-mediated increases in blood pressure (1). Whether these differences are solely due to a species related functional variation remains unclear.
Medicine & Science in Sports & Exercise, 2000
Hemodynamic events leading to spontaneous postexertional vasovagal syncope are not completely und... more Hemodynamic events leading to spontaneous postexertional vasovagal syncope are not completely understood because of the lack of beat-to-beat data. We report a case study of a young athlete who undergoes a syncopal episode during the recovery period following a maximal cycle-ergometer test. The episode was monitored by an impedance cardiograph which can gather noninvasively beat-to-beat the flow of heart rate (HR), stroke volume (SV), cardiac output (CO), diastolic filling rate (SV/DT), and myocardial contractility index (PEP/LVET). The most important findings of this report are the dramatic reduction of SV/DT preceding the syncope, the increment of SV together with the reduction of HR preceding and following the syncope, the prompt recovery of CO values after the syncopal episode despite the bradycardia, and the reduction of PEP/LVET after the syncope. This report confirms the importance of active recovery immediately after strenuous exercise and supports the hypothesis that the reduction of SV/DT in the presence of an inotropic stimulation can trigger the vasovagal reaction.
Journal of Sports Sciences, 2007
Nitroglycerin induces the so-called second window of protection (SWOP), which alleviates myocardi... more Nitroglycerin induces the so-called second window of protection (SWOP), which alleviates myocardial damage and stunning after ischaemia/reperfusion. To determine whether myocardial performance during exercise is improved in the second window of protection, we studied the haemodynamic responses of 12 trained and 11 sedentary individuals during a sequence of maximal tests on a cycle ergometer. A baseline test (basal test) was followed by a second effort performed during the second window of protection (exercise-SWOP test). Haemodynamics was also evaluated after pharmacologically induced SWOP 48 h after transdermal administration of 10 mg of nitroglycerin (pharmacologically induced SWOP test). The exercise-SWOP and pharmacologically induced SWOP tests were separated by a 1-week washout period. Endothelial-dependent vasodilatation after nitroglycerin pre-treatment was also assessed in five sedentary individuals to determine whether nitrate donors could affect vascular function. We found that nitroglycerin pre-treatment did not induce any improvement in haemodynamics in either trained or sedentary individuals, since maximum values of workload, heart rate, stroke volume, cardiac output, myocardial contractility, and double product were similar between the exercise-SWOP and pharmacologically induced SWOP tests in both groups. Furthermore, nitroglycerin pre-treatment did not alter flow-mediated dilation during pharmacologically induced SWOP. Although nitroglycerin pre-treatment alleviates post-ischaemic myocardial stunning, our results suggest that it does not affect the myocardial performance of healthy individuals during exercise performed in the second window of protection, independently of the training status of the individuals. Moreover, nitroglycerin pre-treatment does not ameliorate endothelial function.
Journal of Sports Sciences, 2007
Spinning is a type of indoor fitness activity performed on stationary bikes by participants who p... more Spinning is a type of indoor fitness activity performed on stationary bikes by participants who pedal together to the rhythm of music and the motivating words of an instructor. Despite worldwide popularity of this type of recreational activity, to date there have been few, mainly non-scientific, studies of the impact of spinning on metabolic, respiratory, and cardiovascular functions. The main aim of this study was to evaluate a number of metabolic and cardiovascular variables during a standard 50-min class performed by Spinning instructors of both sexes: six males (age 30 +/- 4.8 years, body mass index 24 +/- 2.5 kg x m(-2); mean +/- s) and six females (age 34 +/- 6.3 years, body mass index 21 +/- 1.9 kg x m(-2)). The mean power output, heart rate, and oxygen uptake during the performance were 120 +/- 4 W, 136 +/- 13 beats x min(-1), and 32.8 +/- 5.4 ml x kg(-1) x min(-1) respectively for males, and 73 +/- 43 W, 143 +/- 25 beats x min(-1), and 30 +/- 9.9 ml x kg(-1) x min(-1) respectively for females. Analysis of individual performances showed that they were compatible with physical exercise that ranged from moderate-to-heavy to very heavy, the latter conditions prevailing. The results show that this type of fitness activity has a high impact on cardiovascular function and suggest that it is not suitable for unfit or sedentary individuals, especially the middle aged or elderly, who are willing to begin a recreational physical activity programme.
Journal of Physics: Conference Series, 2012
ABSTRACT Data concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dyna... more ABSTRACT Data concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dynamic apnoea (DA) were collected from 10 healthy male, elite divers by means of an impedance cardiograph adapted to the underwater environment (C. O. Re., from 2C Technologies Inc, Italy). Three trials were performed by the divers in a 3-m-deep pool with a water temperature of 25°C: 3-minute head-out immersion during normal breathing (A), till exhaustion immersed at the surface (B) and at 3m depth (C). Both B and C conditions did not led to changes in HR, SV and CO compared to A. Data indicate that typical diving response consisting in a reduction of HR, SV and CO was not present during DA, probably due to sympathetic activation induced by exercise during DA, which partially obscured the effects of the diving response. Moreover, this study highlights the innovative role of our portable, impedance cardiography device, i.e. the C. O. Re., in easily assessing cardiodynamic changes in subjects engaged in exercise schedules including phases of underwater, dynamic apnoea.
Journal of Allergy and Clinical Immunology, 2003
The visual analog scale (VAS) is a valid and reliable assessment of pain in clinical studies and ... more The visual analog scale (VAS) is a valid and reliable assessment of pain in clinical studies and has also been used to assess drowsiness associated with antihistamine use. However, no analysis has been undertaken to assess the reliability and reproducibility of VAS in measuring drowsiness and motivation.
Experimental Physiology, 2004
We aimed to investigate haemodynamics during active and passive recovery following repeated bouts... more We aimed to investigate haemodynamics during active and passive recovery following repeated bouts of supramaximal exercise. Seven male athletes underwent two sessions of supramaximal exercise which consisted of a warm-up and of five bouts of cycling at the maximum speed possible for 30 s against a resistance equivalent to 150% of the maximum workload achieved in a previous incremental test. Bouts were separated by 1 min of recovery and followed by 10 min of recovery which was either active (pedalling at 40 W) or passive (completely rest seated on the cycle). Haemodynamic variables were evaluated by means of impedance cardiography. Heart rate (HR), stroke volume (SV), cardiac output (CO), mean blood pressure (MBP), thoracic electrical impedance (Z 0 ) as an inverse index of central blood volume, and systemic vascular resistance (SVR) were assessed. The main findings were that active recovery, with respect to passive recovery, induced higher changes from baseline in HR (+29.1 ± 4.5 versus +15.6 ± 2.9 beats min −1 at the 10th minute of recovery, P < 0.05), SV (+19.9 ± 5.6 versus -6.4 ± 3.3 ml, P < 0.01) and CO (+3.8 ± 1.2 versus +0.4 ± 0.2 l min −1 , P < 0.01). Furthermore, MBP was similar between the two kinds of recovery despite an increase in Z 0 during passive compared to active recovery. These results suggest that the faster haemodynamic recovery towards baseline and the decrease in cardiac preload during passive recovery may be successfully prevented by cardiovascular regulatory mechanisms which include an increase in SVR, thus avoiding a drop in blood pressure.
Experimental Physiology, 2008
Maintained exercise pressor response in heart failure. J. Appl. Physiol. 85(5): 1793-1799.-The im... more Maintained exercise pressor response in heart failure. J. Appl. Physiol. 85(5): 1793-1799.-The impact of forearm blood flow limitation on muscle reflex (metaboreflex) activation during exercise was examined in 10 heart failure (HF) (NYHA class III and IV) and 9 control subjects. Rhythmic handgrip contractions (25% maximal voluntary contraction, 30 contractions/min) were performed over 5 min under conditions of ambient pressure or with ϩ50 mmHg positive pressure about the exercising forearm. Mean arterial blood pressure (MAP) and venous effluent hemoglobin (Hb) O 2 saturation, lactate and H ϩ concentrations ([La] and [H ϩ ], respectively) were measured at baseline and during exercise. For ambient contractions, the increase (⌬) in MAP by end exercise (⌬MAP; i.e., the exercise pressor response) was the same in both groups (10.1 Ϯ 1.2 vs. 7.33 Ϯ 1.3 mmHg, HF vs. Ctl, respectively) despite larger ⌬[La] and ⌬[H ϩ ] for the HF group (P Ͻ 0.05). With ischemic exercise, the ⌬MAP for HF (21.7 Ϯ 2.7 mmHg) exceeded that of Ctl subjects (12.2 Ϯ 2.8 mmHg) (P Ͻ 0.0001). Also, for HF, ⌬[La] (2.94 Ϯ 0.4 mmol) and ⌬[H ϩ ] (24.8 Ϯ 2.7 nmol) in the ischemic trial were greater than in Ctl (1.63 Ϯ 0.4 mmol and 15.3 Ϯ 2.8 nmol; [La] and [H ϩ ], respectively) (P Ͻ 0.02). Hb O 2 saturation was reduced in Ctl from ϳ43% in the ambient trial to ϳ27% with ischemia (P Ͻ 0.0001). O 2 extraction was maximized under ambient exercise conditions for HF but not for Ctl. Despite progressive increases in blood perfusion pressure over the course of ischemic exercise, no improvement in Hb O 2 saturation or muscle metabolism was observed in either group. These data suggest that muscle reflex activation of the pressor response is intact in HF subjects but the resulting improvement in perfusion pressure does not appear to enhance muscle oxidative metabolism or muscle blood flow, possibly because of associated increases in sympathetic vasoconstriction of active skeletal muscle. metaboreflex; hemoglobin oxygen saturation; lactate; hydrogen ion; pH; positive pressure COMPARED WITH HEALTHY INDIVIDUALS, patients with chronic heart failure (HF) demonstrate reduced tolerance for exercise . The mechanism responsible for exercise intolerance is thought to involve reduced muscle vascular conductance (15, 44) causing an imbalance in oxygen delivery and energy requirements. However, altered muscle biochemical properties are also known to occur in human HF patients and in animal models of HF (5), resulting in greater reliance on glycolytic metabolism.
European Journal of Pharmacology, 1978
The unilateral, intranigral administration of kainic acid (k.a.) produced a syndrome characterize... more The unilateral, intranigral administration of kainic acid (k.a.) produced a syndrome characterized by early sequelae of contra- and ipsilateral circling and by a chronic contralateral turning associated with moderate loss of neurons in the pars reticulata. The acute contralateral circling seems to be related to dopaminergic nigro-neostriatal neuron stimulation, since it was prevented by previous intranigral injections of 6-OHDA. The acute ipsilateral circling and the chronic contralateral turning, on the other hand, seem to be independent of the integrity of the dopaminergic system and may be due to an initial stimulation, followed by destruction, of a nigral neuronal system which mediates turning behavior in a manner opposite to that of nigro-striatal dopamine. Treatment with D-amphetamine or apomorphine changed the contralateral into ipsilateral turning, while haloperidol potentiated the contralateral turning. Bilateral injection of k.a. into the nigra resulted in chronic stereotyped sniffing and gnawing, which were not inhibited by haloperidol. Moreover, haloperidol did not produce catalepsy in these animals. It is suggested that the intranigral k.a. injection destroyed a neuronal system antagonistic to dopamine and resulted in a reduction of the response to DA-receptor stimulation of the c. striatum.