PubMed Health⌕ Search

Biomedical subjects

A G Suryaprasad

Publications and source records attributed to A G Suryaprasad.

At least 19 recordsLinked to original sources
PubMed1992

Metabolic and hemodynamic responses to concurrent voluntary arm crank and electrical stimulation leg cycle exercise in quadriplegics.

This study determined the metabolic and hemodynamic responses in eight spinal cord injured (SCI) quadriplegics (C5-C8/T1) performing subpeak arm crank exercise (ACE) alone, subpeak functional electrical stimulation leg cycle exercise (FES-LCE) alone, and subpeak FES-LCE concurrent with subpeak ACE (hybrid exercise). Subjects completed 10 minutes of each exercise mode during which steady-state oxygen uptake (VO2), pulmonary ventilation (VE), heart rate (HR), cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), arteriovenous oxygen difference (a-v O2 diff), and total peripheral resistance (TPR) were determined. Although mean VO2 for both ACE alone and FES-LCE alone was matched at 0.66 l/mi, individualized power outputs ranged from 0-30 W (mean = 19.4 +/- 1.3) and 0-12.2 W (mean = 2.3 +/- 0.6), respectively. Hybrid exercise elicited significantly higher VO2 (by 54 percent), VE (by 39-53 percent), HR (by 19-33 percent), and CO (by 33-47 percent), and significantly lower TPR (by 21-34 percent) than ACE or FES-LCE performed alone (P less than or equal to 0.05). Stroke volume was similar between hybrid exercise and FES-LCE alone, and these two exercise modes evoked a significantly higher SV (by 41-56 percent) than during ACE alone. These data clearly demonstrate that hybrid exercise creates a higher aerobic metabolic demand and cardiac-volume load in SCI quadriplegics than either subpeak levels of ACE or FES-LCE performed separately. Therefore, hybrid exercise may provide more advantageous central cardiovascular training effects in quadriplegics than either ACE or FES-LCE alone.

Adult↗
PubMed1992

Physiologic effects of electrical stimulation leg cycle exercise training in spinal cord injured persons.

The purpose of this study was to assess the physiologic training effects of functional electrical stimulation leg cycle ergometer (FES-LCE) exercise in persons with spinal cord injury (SCI) who were previously untrained in this activity. Ten persons with quadriplegia (C5 to C7) and eight with paraplegia (T4 to T11) performed FES-LCE training on an ERGYS I ergometer 10 to 30 minutes per day, 2 or 3 days per week for 12 to 16 weeks (36 total sessions). Training session power output (PO) ranged from 0.0W (no external resistance) to 30.6W. Each subject completed discontinuous graded FES-LCE and arm crank ergometer (ACE) tests before and after training for determinations of peak lower and upper extremity metabolic, pulmonary, and hemodynamic responses. Compared with pretraining, this SCI group exhibited significantly (p less than or equal to .05) higher posttraining peak PO (+45%), oxygen uptake ([O2], + 23%), pulmonary ventilation (+27%), heart rate (+11%), cardiac output ([Qt], + 13%) and significantly lower total peripheral resistance ([TPR], - 14%) during FES-LCE posttests. There were no significant changes in peak stroke volume (+6%), mean arterial pressure ([MAP], - 5%), or arteriovenous oxygen difference ([a-vO2diff], + 10%) during posttraining FES-LCE tests. In addition, no significant differences were noted for the peak level of any monitored variable during ACE posttests after FES-LCE training. The rise in total vascular conductance, implied by the significant decrease in posttraining TPR during FES-LCE tests, denotes that a peripheral circulatory adaptation developed in the persons with SCI during FES-LCE exercise training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Acute hemodynamic responses of spinal cord injured individuals to functional neuromuscular stimulation-induced knee extension exercise.

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 graded-intensity 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 KE/min/leg) at ankle loads of 0, 5, 10, and 15 kg/leg. Physiologic responses were determined with open-circuit spirometry, impedance cardiography, and auscultation. Comparing rest with peak FNS-KE for both groups combined, FNS-KE exercise elicited significant (p less than 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-kg/leg stages. Physiologic responses of quads and paras were very similar, except for lower (p less than 0.05) arterial pressures, rate-pressure product, and peripheral vascular resistance in quads. This graded FNS-KE exercise up to the 15-kg/leg 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.

Adult↗
PubMed1991

Musculoskeletal responses of spinal cord injured individuals to functional neuromuscular stimulation-induced knee extension exercise training.

This study was conducted to evaluate a newly designed functional neuromuscular stimulation (FNS)-induced knee extension (KE) exercise system that incorporates the most desired features of previously described systems by determining the musculoskeletal responses of spinal cord injured (SCI) individuals to training. A specially designed chair and electrical stimulator were fabricated for FNS-induced KE resistance exercise. Surface electrodes were placed over motor points of the quadriceps muscles, and KE was alternated between legs at an average rate of 6 KE/min/leg. KE testing protocols were developed for pre- and post-training evaluations of performance, and 12 SCI subjects exercise-trained up to three times per week for 36 sessions using a progressive resistance load at ankle level. Pre- and post-training evaluation data were statistically compared using a 0.05 level for significance. Quadriceps muscle performance (strength x repetitions) improved for both legs in all subjects as indicated by significant increases in load resistance and repetitions over the 36-session training period (right leg mean = 1156.0 versus 1624.8 kg.reps, left leg mean = 1127.3 versus 1721.1 kg.reps). In addition, knee range of motion significantly increased (right leg mean = 134 versus 146 degrees, left leg mean = 133 versus 144 degrees). Thigh skinfold, thigh girth, body weight and bone density were not significantly changed. The lack of decrease in bone density in some subjects suggests that the training may retard the rate of bone loss which typically occurs with SCI. No injuries or problems were encountered during testing and training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Physiologic responses of paraplegics and quadriplegics to passive and active leg cycle ergometry.

The purposes of this study were three-fold: (a) to determine acute physiologic responses of spinal cord injured (SCI) subjects to peak levels of leg cycle ergometry utilizing functional neuromuscular stimulation (FNS) of paralyzed leg muscles, (b) to determine the relative contributions of passive and active components of FNS cycling to the peak physiologic responses, and (c) to compare these physiologic responses between persons who have quadriplegia and those who have paraplegia. Thirty SCI subjects (17 quadriplegics and 13 paraplegics) performed a discontinuous graded FNS exercise test from rest to fatigue on an ERGYS 1 ergometer. Steady-state physiologic responses were determined by open-circuit spirometry, impedance cardiography with ECG, and auscultation. In the combined statistics of both groups, it was noted that peak FNS cycling significantly increased (from rest levels) mean oxygen uptake by 255%, arteriovenous O2 difference VO2 and VE, Q and a-vO2 and VCO by 69%, and stroke volume by 45%, while total peripheral vascular resistance decreased by 43%. Mean peak power output for paraplegics (15 W) was significantly higher than for quadriplegics (9 W), eliciting higher peak levels of pulmonary ventilation and sympathetically mediated hemodynamic responses such as cardiac output, heart rate, and systolic and diastolic arterial blood pressure. Passive cycling without FNS produced no statistically significant increases in physiologic responses above the resting level in either group.

Adult↗
PubMed1990

Cardiovascular responses to arm cranking and FNS-induced leg exercise in paraplegics.

Twelve spinal cord-injured males performed arm-crank exercise (ACE) with and without concurrent functional neuromuscular stimulation (FNS) of paralyzed leg muscles to investigate the hypothesis that FNS would augment cardiovascular performance during submaximal ACE. Six men who exhibited vigorous isometric contractions of thigh and calf muscles were classed as "responders" to FNS (R), and the remaining subjects with poor or nonexistent contractions served as "nonresponder controls" (C). Steady-state heart rate and oxygen uptake during ACE at 30, 60, and 90 W were not appreciably different from the ACE + FNS condition. However, cardiac outputs in R were augmented by 30% during FNS at rest (from 4.9 to 6.4 l/min), by 18% during 30-W ACE + FNS (from 8.6 to 10.1 l/min), and by 28% during 90-W ACE + FNS (from 12.1 to 15.6 l/min). Similarly, resting stroke volumes were increased by 18% (9 ml) and by 23% (19 ml) at 60 W during FNS in the R group. Calculated total peripheral resistance was reduced at rest and during 90-W ACE + FNS by approximately 24%. In contrast, no alterations of circulatory hemodynamics were observed for C subjects. These data indicate that FNS-induced contractions of paralyzed leg muscles augment venous return to aid central cardiovascular control during upper-body submaximal exercise in paraplegics.

Adult↗
PubMed1990

Cardiac arrhythmias and electrocardiographic changes during upper and lower gastrointestinal endoscopy.

Ninety-two patients undergoing upper and lower gastrointestinal endoscopy were monitored with holter recording for electrocardiographic changes during the procedures. The electrocardiographic changes were seen in 20.6% of the patients. These included cardiac arrhythmias in 16.2% and ischemic ST-T changes in 4.4% of the patients. The incidence of these changes was more in patients with cardiac (36%) or pulmonary disease (25%) than in patients with no clinical cardiac or pulmonary problem (16%). The patients with baseline electrocardiographic abnormalities also showed higher incidence of such electrocardiographic changes during the endoscopic procedures when compared with patients with normal baseline electrocardiograms (32% vs. 16%).

Adult↗
PubMed1981

Energy cost and cardiopulmonary responses for wheelchair locomotion and walking on tile and on carpet.

The purpose of this study was to compare energy cost and cardiopulmonary responses to wheelchair locomotion and walking on tile and on carpet at 3.0 km . h-1. Nine wheelchair-dependent (WD) and ten able-bodied (AB) individuals served as test subjects. WD subjects were tested for wheelchair locomotion on tile and on carpet, and AB subjects were tested for walking over both floor surfaces. Studied variables included gross energy cost (GEC), net locomotive energy cost (NLEC), pulmonary ventilation (VE) and heart rate (HR) during all test conditions. On tile, GEC and NLEC were found to be lower, whereas VE and HR were higher for wheelchair locomotion than for walking. On carpet, wheelchair locomotion elicited higher values for all variables than walking. In going from tile to carpet, significant increases in these variables were found for wheelchair locomotion, whereas walking elicited similar response magnitudes on both floor surfaces. These results suggest that cardiopulmonary stresses for wheelchair locomotion are higher than for walking, and that a carpet can present an obstacle to wheelchair locomotion which may not be recognised by those who walk.

Adult↗
PubMed1981

Wheelchair exercise performance of the young, middle-aged, and elderly.

The purpose of this study was to quantitate the maximal power output (POmax), peak oxygen uptake (peak VO2), and maximal heart rate (HRmax) for wheelchair ergometer (WERG) exercise performed by three groups of disabled males: young adult (20-30 yr), middle-aged (50-60 yr), and elderly (80-90 yr). These subjects, who were confined to wheelchairs for similar time periods (mean = 11.7 yr), participated in progressive-intensity discontinuous test protocols on a WERG. Lower (P less than 0.01) mean POmax, peak VO2, and HRmax values were found with advancing age groups. In relationship to age, decreases in POmax and HRmax values were best described by parabolic models, whereas decreases in peak VO2 values were best described by a linear model. In comparison with young adults (83 W, 27 ml . kg-1 . min-1), surprisingly low POmax and peak VO2 values were found for the middle-aged (16 W, 10 ml . kg-1 . min-1) and elderly (7 W, 8 ml . kg-1 . min-1). When our peak VO2 data were combined with other data in the literature for upper body exercise by male disabled individuals, a decrease of 0.19 1 . min-1 or 2.9 ml . kg-1 . min-1 per decade of life was found.

Adult↗
PubMed1981

Exercise program for wheelchair activity.

Poor physical fitness of wheelchair-dependent individuals may result in excessive cardiorespiratory responses during locomotion. The purpose of this study was to develop and implement an interval training program (ITP) incorporating wheelchair ergometer (WERG) exercise to improve fitness for wheelchair activity. Of thirteen able-bodied female volunteers, seven were selected to participate in a 5-week ITP, while the remainder served as sedentary controls. Both the exercise training (ET) group and the sedentary control (SC) group completed a standardized fitness test on the WERG before (pre-test) and after (post-test) the 5-week period. Following the ITP, submaximal heart rate, pulmonary ventilation and oxygen uptake responses of the ET group were generally found to be significantly lower during the post-test. These improvements in WERG exercise performance were not observed in the SC group. The ITP may have contributed to adaptations of upper body muscles, improved cardiorespiratory function, and/or a higher level of skill for wheelchair propulsion. We conclude that applying the concepts of interval training to wheelchair exercise may substantially improve the performance and fitness characteristics of wheelchair users. This could reduce the relative stresses of wheelchair locomotion and lead to a higher level of rehabilitation.

Adolescent↗
PubMed1981

Evaluation of myocardial performance during wheelchair ergometer exercise.

Since a relatively high incidence of cardiovascular disease is associated with wheelchair confinement, exercise stress testing techniques should be utilized to assess myocardial performance of wheelchair-dependent individuals. Therefore, the purpose of this study was to apply the techniques of impedance cardiography to graded wheelchair-type exercise. For this, 9 wheelchair-dependent volunteers completed a progressive intensity, discontinuous test on a wheelchair ergometer (WERG) at power outputs (PO) of 10, 20, and 30 watts. An impedance cardiogram (ZCG), electrocardiogram (ECG), and phonocardiogram (PCG) were recorded for 15 sec immediately following steady state exercise. Stroke volume (delta V) calculated from the ZCG was multiplied by steady state heart rate (HR) to estimate cardiac output (Q). The simultaneous recording of the ZCG, ECG, and PCG permitted calculation of systolic time intervals and impedance cardiography contractility indices. Values for delta V, HR, Q, arteriovenous oxygen difference, systolic and diastolic blood pressure, mean systolic ejection rate, the first derivative of the impedance change, and the Heather Index increased with increments in PO. The Q-S2 interval, left ventricular ejection time (LVET), the pre-ejection period (PEP), the ratio of PEP to LVET, and the R-Z interval decreased with increases in exercise intensity. A linear relationship was found between Q and oxygen uptake which was similar to that reported by other investigators for arm exercise. These data indicate that impedance cardiography may be used in conjunction with electrocardiography and phonocardiography for the non-invasive assessment of myocardial performance during wheelchair exercise testing.

Adult↗
PubMed1981

Methodology devised for a program to improve efficiency and reduce risks for wheelchair locomotion.

The purpose of this paper is to present methodology specifically designed for objective study of problems associated with physiological stresses of manual wheelchair use. Excessive metabolic and cardiopulmonary stresses for everyday tasks could hinder rehabilitative efforts and be hazardous for certain patients. Sources of stress include: the relatively small musculature used for propulsion; architectural barriers; low levels of physical fitness; and inefficient wheelchair design. We propose that in order to reduce these stresses, quantitative data related to their mechanisms need to be derived. Therefore, we are conducting studies in the following areas; 1. Quantitation of metabolic, cardiovascular and pulmonary stresses of operating manual wheelchairs over various terrains; 2. Evaluation of physical fitness of wheelchair-dependent patients; 3. Improvement of physical fitness of wheelchair-dependent patients; and 4. Evaluation of the efficiency of various wheelchair designs. This research to date has provided further understanding of problems related to wheelchair confinement and demonstrated techniques to alleviate them. In this way, wheelchair locomotion could become less stressful and thus contribute to a higher level of rehabilitation.

Electrocardiography↗
PubMed1980

Applied physiology for wheelchair design.

The purpose of this study was to evaluate potential wheelchair design changes that may reduce operational energy cost and cardiopulmonary responses. Design changes, which were simulated with a wheelchair ergometer, allowed two techniques of hand-rim propulsion: the usual synchronous application of force (sync), and an asynchronous technique where force was applied one hand at a time in a reciprocal fashion (async). Three hand-rim drive ratios were also simulated: low, normal, and high. Combinations of these force application-drive ratio simulations were evaluated at power output (PO) levels of 30 and 60 kpm.min-1. The async-high combination was found to elicit significantly lower (P less than 0.01) gross caloric output, pulmonary ventilation, and heart rate values, and provide the greatest advantage over conventional sync-normal operation at both PO levels. It appeared that async propulsion and high drive ratio resulted in less wasted movements. Although the async-high combination was superior under these test conditions, other combinations may be necessary to better match various locomotive tasks to individuals of different capabilities.

Adult↗
PubMed1979

An exercise test to evaluate fitness for wheelchair activity.

The purpose of this study was to develop a wheelchair ergometer (WERG) test to evaluate fitness for manual wheelchair activity. Thirty able-bodied females participated in a progressive intensity, discontinuous test where exercise bouts were 4 min in duration interspersed with 5-min rest periods. Physiological responses of oxygen uptake (VO2), respiratory exchange ratio (R), net mechanical efficiency (ME), pulmonary ventilation (VO) and heart rate (HR) were determined during the final minute of exercise at power output (PO) levels of 30, 60, 90, 120 and 150 kpm/min. These responses were generally found to be linearly related to PO, however, net ME initially increased with PO and plateaued at approximately 11 per cent at 90 kpm/min. Criteria for fitness evaluation were based upon: (1) magnitude of physiological responses at each PO level; and (2) the maximal PO level completed.

Adult↗
PubMed1979

Metabolic and cardiopulmonary responses to wheelchair and bicycle ergometry.

To evaluate wheelchair activity in reference to a more familiar mode of locomotion, metabolic and cardiopulmonary responses to wheelchair ergometer (WERG) and bicycle ergometer (BERG) exercise were compared. Eighteen able-bodies subjects were tested on a combination wheelchair-bicycle ergometer. Oxygen uptake (VO2), respiratory exchange ratio (R), pulmonary ventilation (VE), ventilatory equivalent (VE/VO2), percent net mechanical efficiency (ME), and heart rate (HR) were determined at power output (PO) levels of 30, 90, and 150 kpm/min on each ergometer. For WERG and BERG exercise, VO2, VE, and HR increased linearly with PO. Generally, VO2, R, VE, VE/VO2, and HR responses were higher (P less than 0.05) during WERG than BERG exercise at each PO. Blood lactate was determined after 150 kpm/min, and found to be higher (P less than 0.05) during WERG than BERG exercise. ME increased with PO and was lower (P less than 0.05) for WERG than BERG exercise at each PO level. The greater metabolic and cardiopulmonary responses observed during WERG exercise may be due to inefficient biomechanics and the relatively small upper body musculature used for propulsion.

Adult↗