Improvement in hemodynamic responses to metaboreflex activation after one year of training in spinal cord injured humans (original) (raw)
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Spinal Cord Series and Cases, 2019
Study design Repeated measures within-subjects crossover study. Objectives High intensity interval exercise (HIIE) elicits higher oxygen consumption (VO 2) and heart rate (HR) versus moderate intensity continuous exercise (MICE) in men with spinal cord injury (SCI). No study has compared hemodynamic responses to HIIE versus MICE in SCI. In this study, we determined hemodynamic and cardiorespiratory responses to different bouts of arm cycling in men with SCI.
2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2011
This paper presents the results of cardiovascular changes that occur during a novel rehabilitation strategy called activity based therapy (ABT). Blood volume pulse (BVP) signals were measured during functional electrical stimulation (FES)-induced cycling in adults with spinal cord injury (SCI) persons and results were compared to a passive cycling task and able-bodied controls performing normal cycling. BVP signals were compared during three conditions, a baseline pre-exercise condition, 5 minutes after exercise and after 30-minutes rest following exercise. Exercise recovery was evaluated using normalized inner products values in BVP signals. The results showed that FES-induced cycling in SCI participants resulted in a significantly greater peripheral resistance level and longer time to recover from exercise compared with passive cycling and normal cycling in able-bodied controls.
Reproducibility of noninvasive cardiac output during arm exercise in spinal cord injury
The Journal of Rehabilitation Research and Development, 2007
The carbon dioxide (CO 2 ) rebreathing method is a noninvasive technique to estimate cardiac output during exercise, but few data are available on the validity and reliability of this measure in individuals with spinal cord injury (SCI). Sixteen male subjects with SCI (mean age 45 +/− 9, seven paraplegic and nine tetraplegic) underwent three submaximal steady state arm ergometer exercise tests. We estimated cardiac output using the exponential CO 2 rebreathing technique at an individualized exercise intensity approximating 50% of peak oxygen uptake. Mean values for the cardiac output measurements were 13.0 +/− 2.4, 13.3 +/− 2.0, and 13.4 +/− 1.7 L/min; the difference among the trials was not significant (p = 0.54). The typical error was 1.80 +/− 0.85 L/min, the limits of agreement were 11.3 to 15.3 L/min, the coefficient of variation was 5.4% +/− 3.4%, and the intraclass correlation coefficient was 0.85 (95% confidence interval = 0.70-0.94). The test-to-test variation in estimated cardiac output during arm ergometry in individuals with SCI is similar to that observed in studies that used this technique in ambulatory persons. The 5% relative variation between tests suggests that the CO 2 rebreathing technique for estimating cardiac output can be performed in SCI individuals with acceptable reproducibility.
Muscle Metaboreflex-Induced Increases in Stroke Volume
Medicine & Science in Sports & Exercise, 2003
Purpose: Accumulation of by-products of metabolism within skeletal muscle may stimulate sensory nerves, thus evoking a pressor response named muscle metaboreflex. The aim of this study was to evaluate changes in central hemodynamics occurring during the metaboreflex activation. Methods: In seven healthy subjects, the metaboreflex was studied by postexercise regional circulatory occlusion at the start of the recovery from a mild rhythmic forearm exercise. Central hemodynamics was evaluated by means of impedance cardiography. Results: The main findings of this study were that, with respect to rest, the metaboreflex: 1) raised mean blood pressure (ϩ13%; P Ͻ 0.01); 2) enhanced myocardial contractility (Ϫ12% in preejection period/left ventricular ejection time ratio; P Ͻ 0.01); 3) prolonged diastolic time (ϩ11%; P Ͻ 0.01); 4) increased stroke volume (ϩ 10%; P Ͻ 0.05); and 5) increased cardiac output (ϩ6%; P Ͻ 0.05). These responses were present neither during recovery without circulatory occlusion nor during circulatory occlusion without prior exercise. Moreover, the metaboreflex did not affect systemic vascular resistance and induced bradycardia with respect to recovery without circulatory occlusion. Conclusion: These results suggest that the blood pressure response during metaboreflex activation after mild rhythmic exercise is strongly dependent on the capacity to increase cardiac output rather than due to increased vascular resistance.
The precarious circulatory pressure after a spinal cord injury is not yet regularly analyzed or perhaps anticipated depending on the level and occurrence of the injury (i.e. the American Spinal Injury Affiliation Impairment Scale (AIS) arrangement). Our goal was to investigate the hemodynamic response to a sitting test in a large cohort of people with constant spinal cord injury in order to better understand the cardiovascular capacity of this population. A constant pulse was also recorded on the ECG of people with SCI (n = 167) and people without injury (n = 49). We found that orthostatic hypotension occurred within each AIS level and order (n = 38). In addition, 47 people with constant spinal cord injury experienced a decrease in circulatory pressure that did not fit the patterns of orthostatic hypotension, but was accompanied by a sensational rise in pulse rate, reflecting orthostatic fanaticism. Our current research was conducted at Mayo Hospital, Lahore from March 2019 to February 2020. A group study of the hemodynamic response at a sited position identified eight specific examples of pulse-pulse communication during orthostatic stress, demonstrating delayed autonomic responses. Algorithmic group examination of pulse and circulatory effort is more difficult to diagnose orthostatic cardiovascular dysregulation. This shows that circulatory stress insecurity cannot be anticipated by the level and realization of IBS, and the significance of the orthostatic hypotension tuning joint is missing to represent the fluctuation of circulatory stress and the heart's reactions during orthostatic pressure. Circulatory pressure and pulse responses are intended to represent autonomic capacity after spinal cord injury.
Effects of acute vasodilation on the hemodynamic response to muscle metaboreflex
AJP: Heart and Circulatory Physiology, 2013
Marongiu E, Piepoli M, Milia R, Angius L, Pinna M, Bassareo P, Roberto S, Tocco F, Concu A, Crisafulli A. Effects of acute vasodilation on the hemodynamic response to muscle metaboreflex. The aim of the present study was to test the contribution of stroke volume (SV) in hemodynamic response to muscle metaboreflex activation in healthy individuals. We hypothesized that an acute decrease in cardiac afterload and preload due to the administration of a vasodilating agent could reduce postexercise muscle ischemia (PEMI)-induced SV response. Ten healthy males (age 33.6 Ϯ 1.3 yr) were enrolled and randomly assigned to the following study protocol: 1) PEMI session, 2) control exercise recovery (CER) session, 3) PEMI after sublingual administration of 5 mg of isosorbide dinitrate (ISDN), and 4) CER after ISDN. Central hemodynamics were evaluated by means of impedance cardiography. The main findings were a blunted SV response during metaboreflex following acute arterial and venous vasodilation, associated with a reduction in cardiac diastolic time and filling, and a decrement of systemic vascular resistance. These hemodynamic changes restrain blood pressure response during metaboreflex activation. Our results indicate that hemodynamic response to metaboreflex activation is a highly integrated phenomenon encompassing complex interplay between heart rate, cardiac performance, preload, and afterload and that impairment of one or more of these parameters leads to altered hemodynamic response to metaboreflex.
The Journal of Rehabilitation Research and Development, 1991
The purpose of this study was to determine and compare acute hemodynamic responses of spinal cord injured (SCI) quadriplegics (quads), and paraplegics (paras) during a gradedintensity knee extension (KE) exercise test utilizing functional neuromuscular stimulation (FNS) of paralyzed quadriceps muscles. Seven quads and seven paras (N=14) performed a series of 4-minute stages of bilateral alternating FNS-KE exercise (approximately zero to 70 degree range of motion at the knee and 6 KEIminlleg) at ankle loads of 0, 5, 10, and 15 kglleg. Physiologic responses were determined with open-circuit spirornetry, impedance cardiography, and auscultation. Comparing rest with peak FNS-KE for both groups combined, FNS-KE exercise elicited significant (p< 0.05) increases in oxygen uptake (130 percent), pulmonary ventilation (120 percent), respiratory exchange ratio (37 percent), arteriovenous oxygen difference (57 percent), cardiac output (32 percent), stroke volume (41 percent), mean arterial pressure (18 percent), and rate-pressure product (23 percent). Heart rate increased significantly by 11 percent from the 5-to the 15-kglleg stages. Physiologic responses of quads and paras were very similar, except for lower (p < 0.05) arterial pressures, rate-pressure product, and peripheral vascular resistance in quads. This graded FNS-KE exercise up to the 15-kglleg load induced relatively small but appropriate increases in aerobic metabolism and cardiopulmonary responses that appear to be safe and easily tolerated by quads and paras. Arterial pressure needs to be monitored carefully in quads to prevent excessive hypertension or hypotension. Although FNS-KE exercise has been shown to elicit peripheral adaptations to improve muscle strength and endurance, it is probably not an effective central cardiovascular training tool for all but the least fit SCI individuals. This information is important for understanding the effects of FNS use during more complex activities such as cycling and ambulation.
Systolic and diastolic function in chronic spinal cord injury
PLOS ONE, 2020
Individuals with spinal cord injury develop cardiovascular disease more than age-matched, non-injured cohorts. However, progression of systolic and diastolic dysfunction into cardiovascular disease after spinal cord injury is not well described. We sought to investigate the relationship between systolic and diastolic function in chronic spinal cord injury to describe how biological sex, level, severity, and duration of injury correlate with structural changes in the left ventricle. Individuals with chronic spinal cord injury participated in this study (n = 70). Registered diagnostic cardiac sonographers used cardiac ultrasound to measure dimensions, mass, and systolic and diastolic function of the left ventricle. We found no significant relationship to severity or duration of injury with left ventricle measurements, systolic function outcome, or diastolic function outcome. Moreover, nearly all outcomes measured were within the American Society of Echocardiography-defined healthy range. Similar to noninjured individuals, when indexed by body surface area (BSA) left ventricle mass [-14 (5) g/ m2, p < .01], end diastolic volume [-6 (3) mL/m 2 , p < .05], and end systolic volume [-4 (1) mL/m 2 , p < .01] were significantly decreased in women compared with men. Likewise, diastolic function outcomes significantly worsened with age: E-wave velocity [-5 (2), p < .01], E/ A ratio [-0.23 (0.08), p < .01], and e' velocity [lateral:-1.5 (0.3) cm/s, p < .001; septal:-0.9 (0.2), p < .001] decreased with age while A-wave velocity [5 (1) cm/s, p < .001] and isovolumic relaxation time [6 (3) ms, p < .05] increased with age. Women demonstrated significantly decreased cardiac size and volumes compared with men, but there was no biological relationship to dysfunction. Moreover, individuals were within the range of ASE-defined healthy values with no evidence of systolic or diastolic function and no meaningful relationship to level, severity, or duration of injury. Decreases to left ventricular dimensions and mass seen in spinal cord injury may result from adaptation rather than maladaptive myocardial remodeling, and increased incidence of cardiovascular disease may be related to modifiable risk factors.