[Respiratory impairments and aerobic physical activity in low-cervical spinal cord injuries].
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Cervical Vertebrae↗
Biomedical subjects
M Sagiv
Publications and source records attributed to M Sagiv.
Left ventricular function during combined isometric and dynamic exercise-induced ST depression in coronary artery disease.
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Coronary Circulation↗
Effects of gradient and load carried on human haemodynamic responses during treadmill walking.
This study examined the effects of different loads carried and gradients, on haemodynamic and cardiovascular responses during 45 min of treadmill walking. A group of 20 male endurance-trained athletes [mean maximal oxygen uptake 61.4 (SD 4) ml x kg(-1) x min(-1)] volunteered for this study. The subjects took part in three separate trials. The first involved a backpack weighing 25 kg, the second a 35 kg backpack, and the third trial, unladen, while walking on a treadmill at a speed of 5 km x h(-1). The subjects began walking on the treadmill with the randomized load at 0% gradient. After 15 min, the gradient was increased by 5% every 15 min for a total of 45 min. The order of the loads carried was randomized among subjects. No significant differences were noted for all the variables measured attributable to loads between 25 kg and 35 kg. However, significant (P<0.05) differences were seen for all variables each time the gradient was increased. Cardiac output increased from 11.4 (SD 0.6) 1 x min(-1) at 0% to 13.6 (SD 0.8) l x min(-1) at 5% and to 17.6 (SD 1.3) l x min(-1) at 10% carrying the 35 kg load. Similarly, lactic acid concentrations in the blood increased from 2.8 (SD 0.2) to 3.1 (SD 0.6) and to 5.3 (SD 1.3) mmol x l(-1), respectively. Similar changes were observed for all variables while carrying the 25 kg load. In addition, steady states in oxygen uptake and other physiological variables were obtained throughout the course of the tests. These data suggest that during isodynamic exercise, one of the main factors determining metabolic and haemodynamic responses will be the change in gradient and to a lesser extent, the mass of the load carried.
Adolescent↗
Left ventricular contractility and function at peak aerobic and anaerobic exercises.
PURPOSE: The present study compared and evaluated left ventricular function and contractility at peak incremental aerobic type exercise and all-out explosive anaerobic effort in young healthy trained subjects. METHODS: Twenty-two young healthy trained subjects (19 +/- 1 yr) were studied by two-dimensional direct M-mode echocardiography at peak aerobic and at peak all-out anaerobic exercises, performed on cycle ergometer. RESULTS: All subjects completed the study without any electrocardiographic abnormalities. Significant (P < 0.05) differences between the aerobic and the anaerobic efforts were noted for peak cardiac output (24 +/- 2.0 and 15.0 +/- 1.1 L x min (-1), respectively), left ventricular pressure-volume ratio (5.8 +/- 0.6 and 4.7 +/- 0.5 respectively), end systolic volume (33 +/- 4 and 42 +/- 5 mL, respectively), ejection fraction (79 +/- 7 and 66 +/- 5%, respectively), and total peripheral resistance (TPR) (367 +/- 90 and 704 +/- 90 dynes x s(-1) x cm(- 5), respectively). CONCLUSIONS: These data suggest that left ventricular at peak all out anaerobic effort differed markedly from those observed at peak aerobic exercise. These differences are presumably due to the different after-load responses between the two exercise modes. Therefore, it is suggested that anaerobic-type effort should be performed with great caution in normal young healthy subjects.
Adolescent↗
Dilated inferior vena cava: a common echocardiographic finding in highly trained elite athletes.
Typical structural features of the athlete's heart as defined by echocardiography have been extensively described; however, information concerning extracardiac structures such as the inferior vena cava (IVC) is scarce. Fifty-eight top-level athletes and 30 healthy members of a matched control group underwent a complete Doppler echocardiographic study. IVC diameter was determined in the subxiphoid approach 10 to 20 mm away from its junction to the right atrium. Measures reflect the median values between maximal inspiratory and expiratory values. IVC respiratory collapsibility index was determined as well. IVC in athletes was 2.31 +/- 0.46 cm compared with 1.14 +/- 0.13 cm in the control group (P <.001). Swimmers had an IVC diameter of 2.66 +/- 0.48 cm compared with 2.17 +/- 0.41 cm in other athletes (P <.05). The IVC was normal ( /=2.6 cm) in 24.1% of athletes. The collapsibility index was 58% +/- 6.4% in athletes compared with 70.2% +/- 4.9% in the control group (P <. 001). Correlation was found between IVC size and VO(2) max (r = 0.81, P <.001) and the right ventricle (r = 0.81, P <.001) and with collapsibility index (r = -0.57, P <.05). Multiple regression analysis showed the impact of VO(2) max, cardiac index, and right ventricular and left ventricular end-diastolic dimensions on IVC diameter. IVC dilatation probably represents adaptation of an extracardiac structure to chronic strenuous exercise in top-level, elite athletes.
Adolescent↗
Perceptual responses to exercise: the effect of load-awareness on physiological responses during an isometric bout.
To evaluate the effect of awareness of load on cardiovascular and metabolic responses, thirty males were compared in three different loads during upright deadlift isometric exercise, at 25%, 30% and 35% of maximal voluntary contraction for 3 min. Significant differences (P < 0.05) were found from rest to 25%, 30% and 35% for all physiological variables, heart rate (66.5+/-9.0, 104.0+/-12.0, 115.0+/-9.0, and 123.0+/-11.0 beats x min(-1), respectively), and for lactic acid (2.2+/-0.4, 4.6+/-0.7, 5.7+/-1.1, and 6.3+/-1.5 mM x l(-1), respectively). However, no significant differences were revealed between the various conditions when rate-perceived exertion data were analyzed, despite increased absolute loads. These data indicate that the psychological manipulation introduced in this study did not affect physiological responses during isometric exercise, in contrast to that seen during dynamic exercise.
Adult↗
Direct vs. indirect blood pressure measurement at peak anaerobic exercise.
The present study compared the direct intra-arterial method with the indirect conventional sphygmomanometer during all-out anaerobic exercise, in young healthy subjects. Systolic and diastolic blood pressures were measured by intraarterial means and by auscultation. Fourteen young healthy males (23+/-2 yrs) were measured at rest and during all-out anaerobic exercise. Comparisons were made with simultaneously determined intra-arterial catheter and auscultation measurements. The data suggest that indirect systolic pressure is highly correlated with the direct method at rest (r = 0.684), with mean of 107+/-7 and 101+/-6 mmHg, respectively, and during all-out anaerobic exercise (r = 0.87), with mean of 197+/-11 and 191+/-9 mmHg, respectively. Indirect diastolic blood pressure correlates well with intra-arterial at rest (r = 0.62), with mean of 84+/-11 and 77+/-9 mmHg, respectively. However, during all-out anaerobic exercise, the correlation coefficient between the direct and the indirect methods was low (r = 0.36), with mean of 101+/-12 and 103+/-9 mmHg, respectively. These results suggest that when utilizing an all-out anaerobic exercise, the indirect method is not valid for assessment of diastolic pressure. In addition, although the anaerobic test is a dynamic type of exercise, its blood pressure responses for both direct and indirect methods were similar to those seen during isometric exercise.
Adult↗
The effect of gender on left ventricular function immediately after the wingate test.
The effect of gender on left ventricular systolic function and exercise haemodynamics in healthy young subjects was studied during 30-s all-out sudden strenuous dynamic exercise. A group of 22 men [19.3 (SD 1) years] 20 women [19.1 (SD 1) years] volunteered to participate in this study. Two-dimensional direct M-mode and Doppler echocardiograph studies were performed with the subject in the sitting position. The Doppler examination of flow was located with continuous-wave, interrogating ascending aorta measurements. The subjects completed the study without showing any electrocardiograph abnormalities. An interaction effect with stroke volume (P < 0.05) was characterized by a decrease in the men and an increase of stroke volume in the women. Cardiac output rose significantly (P < 0.05) up to 14.5 (SD 6) 1.min-1) for the men and 12.1 (SD 4) 1.min-1 for the women compared to the rest values [5.8 (SD 0.4) and 4.7 (SD 0.5) 1.min-1, respectively]. Flow velocity integral and acceleration time differed significantly between the two groups at rest (P < 0.05). During exercise these differences showed an interaction effect (P < 0.05). These results would indicate that normal men and women respond to sudden strenuous exercise by reducing their left ventricular systolic function, with a significantly greater decrease in women (P < 0.05). The gender differences in the haemodynamic responses during the present study, may, as suggested by others, be attributable to differences in energy metabolism. In addition, changes in Doppler parameters of aortic flow, haemodynamics and blood pressure responses during sudden strenuous exercise differed markedly from those seen before with endurance exercise.
Adolescent↗
Effects of chronic overload training and aging on left ventricular systolic function.
To examine the effects of age and chronic overload training on left ventricular systolic function during static exercise, Doppler echocardiography studies were performed in 14 young (28 +/- 6 years) and 10 older (51 +/- 3 years) weight lifters and also in 14 young (29 +/- 6 years) and 10 older (52 +/- 1.1 years) normal individuals during upright dead-lift isometric exercise, at 30% of maximal voluntary contraction for 3 min. At rest, older weight lifters demonstrated impaired left ventricular systolic function as compared with the other three groups. During exercise, peak and mean velocity values increased significantly (p < 0.05) from resting values in the young groups, but remained unchanged in the older groups. Flow period and acceleration and deceleration times were significantly (p < 0.05) lower in the younger subjects than those observed for the old ones, with the highest (p < 0.05) values obtained by the old weight lifters. This study suggests that the differences between the groups are related to differences in impedance and not to fundamental changes in the properties of the myocardium.
Adult↗
The effects of isometric stress on left ventricular filling in athletes with isometric or isotonic training compared to hypertensive and normal controls.
Hypertrophy of the left ventricle may be associated with altered left ventricular filling dynamics. To test whether isometric and isotonic training affect left ventricular filling differently at rest and during isometric stress, 38 males, 13 long distance runners, eight weight-lifters, eight hypertensive patients and nine age-matched healthy male controls with a mean age of 30 +/- 7 years, were studied before and after 90 s of 50% maximal handgrip force. Left ventricular Doppler filling parameters were compared in the four groups while they were resting and during isometric stress testing, and the results assessed in relation to left ventricular mass index and wall stress. All subjects had normal resting filling patterns except for hypertensive patients, and peak meridional wall stress was low in both athletic groups at rest. Weight-lifters had a hypertensive response during isometric stress testing, associated with a reduction in peak E velocity and a marked increase in peak A velocity, resembling the filling pattern in hypertensive subjects. In runners the filling pattern remained normal. Thus, while the resting left ventricular pattern was normal in all athletes, isometric stress testing was associated with a hypertensive filling pattern only in weight-lifters compared to normal filling in runners.
Adult↗
Influence of the time of day on physical performance in patients with coronary artery disease.
The exercise training workload for cardiac patients is determined from the peak heart rate achieved safely during a stress test. Circadian rhythms may play a key role in changing physiological responses to the stress test. Therefore, the purpose of this study was to evaluate the influence of the time of day on cardiopulmonary and metabolic responses in highly trained men with coronary artery disease. A group of 15 patients with coronary artery disease [53.5 (SD 6) years] performed two sessions of graded tests to exhaustion: one session was performed at 10 a.m. and the second at 5 p.m. in randomized order. Treadmill velocity was kept constant at a speed of 4.8 km h-1 starting with an elevation of 0% which was increased thereafter by 2.5% every 3 min. At rest the results revealed that only oxygen uptake was significantly lower (P < 0.05) in the morning compared to that observed in the evening [2.9 (SD 0.4) compared to 3.5 (SD 0.5) ml O2.kg-1.min-1, respectively]. During exercise, differences due to time of day were found in the variables of maximal oxygen uptake which were significantly higher (P < 0.05) in the evening than in the morning [34.2 (SD 2.6) and 40.8 (SD 2.5) ml O2.kg-1.min-1, respectively]. These data indicated that in these well-trained coronary artery disease patients there was a significant time of day effect associated with metabolic responses following stress-testing.
Circadian Rhythm↗
Clomiphene citrate reduces procarbazine-induced sterility in a rat model.
Chemotherapy with the cytotoxic drug procarbazine (PCB) causes permanent infertility in most male patients. Since many patients treated with this cytotoxic drug are of reproductive age, it is important to develop a method to protect spermatogenesis and fertility. It has been hypothesised that 'spermatogenic arrest' by pharmacological intervention may render the testes less susceptible to the effects of chemotherapy. The present study investigated whether recovery of fertility in a male rat model could be achieved by suppression of spermatogenesis with high doses of clomiphene citrate (CC) prior to PCB administration. It was demonstrated that young male rats treated with a combination of CC and PCB partially recovered spermatogenesis and achieved almost normal fertility. In contrast, animals treated with PCB alone exhibited abnormal spermatogenesis and remained infertile.
Animals↗
Direct vs indirect blood pressure at rest and during isometric exercise in normal subjects.
Systolic and diastolic blood pressures were measured by intraarterial means and by auscultation. Comparisons were made with simultaneously determined intraarterial catheter and auscultation measurements. Five healthy males were measured at rest and during handgrip and deadlift isometric exercises, utilizing small and large muscle mass. The data suggest that indirect systolic blood pressure is highly correlated with the direct method at rest, during handgrip and deadlift (0.8, 0.9 and 0.91 respectively) isometric exercises. Indirect diastolic blood pressure correlates well with intraarterial at rest (0.7) and during the isometric handgrip bout which utilized small muscle mass (0.8). As for the deadlift manoeuvre, the correlation coefficients between the indirect and direct methods were low. These results suggest that when utilizing large muscle mass during isometric deadlift exercise, the indirect method is not valid for assessment of diastolic blood pressure.
Adult↗
Aerobic capacity and anaerobic threshold of wheelchair basketball players.
This study evaluated the aerobic capacity and anaerobic threshold of national level Israeli wheelchair basketball players. Subjects were tested working on a wheelchair rolling on a motor driven treadmill and on an arm cycle ergometer. Metabolic and cardiopulmonary parameters were measured during graded maximal exercise tests. Blood lactic acid (LA) concentration was measured in the intervals between loads during the test on the wheelchair. Heart rate (HR) and % heart rate reserve (%HRR) corresponding to the anaerobic threshold (4 mM blood LA) were evaluated while working on the wheelchair rolling on a motor driven treadmill. While working on the wheelchair the following peak exercise values were obtained: VO2 = 24.7 ml.kg/min, VE = 92.09 l/min HR = 181.5 b/min and R = 1.22. Values corresponding to the anaerobic threshold were found to be, HR = 139 b/min and %HRR = 57.02. Low correlations were obtained between peak exercise VO2 and VE measured while working on the wheelchair and those measured with arm cycle ergometer (r = 0.57 p = 0.137 and r = 0.4 p = 0.233 respectively). As athletes, subjects in the present study may be classified as having a low aerobic capacity and anaerobic threshold. It is also concluded that the ergometer type may have an important influence on test results.
Adult↗
Influence of physical work on high density lipoprotein cholesterol: implications for the risk of coronary heart disease.
Physically trained individuals differ greatly from untrained counterparts in their high density lipoprotein (HDL) cholesterol blood levels. Such differences in turn may have implications for long-term preventive policies in coronary artery disease. In prospective studies, exercise programs in men, but seldom in women, have been shown to independently raise HDL cholesterol (HDL-C) concentrations in the blood. This evidence is of major interest because of the voluminous epidemiologic evidence for low blood levels of HDL-C as a risk factor for coronary heart disease. Experimental evidence is still missing to establish the efficacy of elevating blood HDL-C concentrations in actually reducing the risk of incident, or recurrent, coronary events. If the efficacy of elevating blood levels of HDL-C in ameliorating coronary prognosis is demonstrated, the recommendation for hygienic means, primarily physical exercise, will be reinforced. The role of physical training in elevating blood HDL-C is examined and plausible mechanisms for the observed experimental results are reviewed.
Cholesterol, HDL↗
Left ventricular responses during prolonged treadmill walking with heavy load carriage.
This study examined with metabolic cart and echo-Doppler the influence of different load carriage during 4 h of treadmill walking on left ventricular systolic function, hemodynamics, and cardiovascular responses. Twenty-six aerobically well-trained male subjects (VO2max = 65.2 +/- 5 ml.kg-1.min-1) volunteered for this study. Subjects carried a load of 38 kg during one session and a load of 50 kg during the other session. Following the 4-h exercise in each session, significant (P < 0.05) differences were noted between the 38-kg and 50-kg workloads with regard to VO2: 14.4 +/- 2 and 19 +/- 5 ml.kg-1.min-1; heart rate: 104 +/- 14 and 125 +/- 17 beats.min-1; diastolic blood pressure: 69 +/- 4 and 79 +/- 4 mm Hg; and rate pressure product 140.4 +/- 15 and 173.8 +/- 20 index.10(-2), respectively. No significant differences were noted between the workloads in regard to systolic blood pressure, perceived exertion rating, and aortic valve Doppler indices. We concluded that during prolonged treadmill walking in well-trained young subjects, the additional load above 50% up to 66% of body weight did not change the steady state of left ventricular systolic function, hemodynamics, and cardiovascular responses throughout the course of the 240 min of effort.
Adult↗
Comparison between end-systolic pressure-volume and end-systolic wall stress in determining left ventricular contractility with increased afterload.
This study compared end-systolic pressure-volume relationship (P/V) versus wall stress index (WS) as a tool for the evaluation of ventricular contractile state during upright isometric exercise. Both indices of contractility exhibit significant (p < 0.001) increase during exercise compared to resting values. The correlation coefficients for the two indices of contractility were r = -0.45 for exercise and r = -0.70 for rest. Both were significant at the p < 0.01 level. The correlation of the difference scores between rest and exercise as computed by both indices was low (-0.20) and insignificant. These data suggest that changes in contractility from rest to exercise as measured by one index do not reflect the pattern of individual differences that are measured by means of the other index. However, from a reliability point of view, it seems appropriate to prefer the use of P/V index over the WS index in order to determine contractile state.
Adult↗
Cyclophosphamide, doxorubicin, dexamethasone and procarbazine: effect on seminal plasma sialyltransferase activity.
The influence of chemotherapy agents, doxorubicin (adriamycin), cyclophosphamide, procarbazine, and dexamethasone on the activity of sialyltransferase in human semen has been examined. Aliquots of 25 mcL semen were incubated for 2 hours with the above substances at concentrations ranging from 10 to 800 mcg/incubation mixture. The measurement of sialyltransferase activity was based on the incorporation of radioactive sialic acid from CMP (14) C sialic acid) into asialofetuin. Doxorubicin and cyclophosphamide, at the maximal concentration of 800 mcg/incubation mixture exhibited an inhibiting effect on sialyltransferase activity which accounted for 15.7 +or- 16% and 12.2 +or- 16%, respectively. The rate of inhibition following incubation with maximal doses of dexamethasone (400 mcg) was 25.3 +or- 13%, respectively. The rate of inhibition following incubation with maximal doses of dexamethasone (400 mcg) was 25.3 +or- 12%. Inhibition caused by procarbazine did not exceed 5%. Inhibition of sialyltransferase in human semen by the materials examined in this study can diminish the transfer of sialic acid, thus interfering with normal glycoprotein's and glycolipid's syntheses in semen and possibly also in other fluids and tissues.
Asia↗