Biomedical subjects

K H Pitetti

Publications and source records attributed to K H Pitetti.

32 records · Page 2Linked to original sources

PubMed1992

Isokinetic arm and leg strength of adults with Down syndrome: a comparative study.

This study compared isokinetic arm (elbow flexion and extension) and leg (knee flexion and extension) strength of individuals with Down syndrome (DS), with mental retardation without DS (NDS), and sedentary young adults with no mental retardation (NMR). Eighteen individuals with DS, NDS, and NMR (11 men and seven women in each group) performed strength tests on a Cybex 340 isokinetic dynamometer. Parameters measured were peak torque (ft/lb), peak torque percent body weight (%BW), average power (watts), and average power %BW. Subjects with mental retardation (ie, DS and NDS groups) performed the test on two separate days with best test results chosen for statistical comparisons. The NMR group performed the test once. In all isokinetic strength parameters measured for arm strength, the NMR group demonstrated significantly higher scores than subjects with DS and NDS. Subjects with DS and NDS displayed similar test results. Similarly, for all the isokinetic strength parameters measured for leg strength, NMR demonstrated significantly higher scores than subjects with DS and NDS. Subjects with NDS, however, averaged significantly higher test results than subjects with DS for leg strength. The results of this study indicate that both subject populations who were mentally retarded exhibited lower arm and leg strength than the NMR subjects. Additionally, subjects with DS demonstrated inferior leg strength when compared to their peers with NDS.

Adult↗

PubMed1992

The cardiovascular capacities of adults with Down syndrome: a comparative study.

The purpose of this study was to compare the cardiovascular capacities of individuals with Down syndrome (DS) to individuals without Down syndrome who are mentally retarded. Sixteen young adults with DS and 16 individuals without DS (12 males and 4 females, respectively), all with mild/moderate mental retardation, participated in this study. Peak VO2 (absolute and relative), VE (1.min-1), heart rate (HR, b.min-1), and RER (VCO2/VO2) were determined by exercise tests utilizing a treadmill (TM) and Schwinn Air-Dyne ergometer (SAE). The best test result was chosen from the TM and SAE tests and used for statistical comparisons. Cardiac output (Q, 1.min-1) was measured while standing quietly and while walking at 3 mph, 0% grade, using the CO2 rebreathing method for 11 (9 males and 2 females) subjects from each group. Arteriovenous oxygen differences (a-v O2), cardiac index (QI), and stroke volume (SV) were calculated from VO2, Q, HR, and body surface area. Peripheral vascular resistance (PVR), left ventricular work index (LVWI), and left ventricular stroke work index (LVSWI) were calculated from mean arterial pressure, Q, QI, and stroke volume index. Results showed that individuals without DS had statistically significant (P less than 0.01) higher mean peak VO2 (35.6 vs 24.6 ml.kg-1.min-1; 2567 vs 1683 ml.min-1), VE (89.3 vs 59.2 1/min-1), and HR (179 vs 159 b.min-1) than individuals with DS, respectively. No differences in RER were seen between the groups. No differences were seen in cardiovascular parameters measured while quietly standing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Mentally retarded individuals--a population at risk?

When comparing the aging process of mentally retarded (MR) persons with the nondisabled population, researchers have established an earlier lower limit for the onset of old age for MR persons and a higher mortality rate. The reason for early senescence has not been successfully resolved, but the finding that cardiovascular disorders are the most prevalent form of disease among elderly MR persons suggests a relationship between lifestyles and higher mortality rate. Indeed, studies that evaluated the cardiovascular fitness (CVF) of MR individuals demonstrated substandard levels of fitness. The results of these studies, however, are not conclusive due to variation in test methodologies, motivational factors, and issues of test validity and reliability. Training studies which have purported to determine trainability of this population have also shown confusing results, perhaps attributed to the same protocol inconsistencies. Therefore, the purposes of this article are 1) to review previous methods of evaluating CVF of MR adults and determine whether testing methodologies invalidate the results of these studies, 2) to review training studies involving adult MR individuals and determine whether this population is capable of improving their CVF, and 3) to identify areas where further research is needed to fully describe the functional cardiovascular characteristics of MR adults.

Cardiovascular Diseases↗

PubMed1991

Effects of a minimally supervised exercise program for mentally retarded adults.

Previous exercise studies that attempted to improve the cardiovascular fitness (CVF) of mentally retarded (MR) adults were flawed with methodological shortcomings that prevented conclusive results. At issue in these training studies were fitness test validity and reliability, exactness of duration and intensity of training, and an inordinate amount of supervision. Therefore, we sought to determine whether moderately MR adults (seven males, five females; IQ = 61 +/- 3, age = 25 +/- 3 yr) could improve their CVF through a minimally supervised 16-wk training program. Each subject repeated exercise tests twice on two different modes of exercise, the treadmill (TM) and Schwinn Air-Dyne ergometer (SAE), before training to ensure validity and reliability of initial CVF levels. Intensity and frequency of exercise were closely monitored. An observer was present during the training bouts, but, following initial instructions, no additional encouragement or instructions were given. Although the training program significantly increased peak VO2 (29.2 +/- 8 to 33.5 +/- 9 ml.kg-1.min-1) and peak ventilation (73 +/- 26 to 81 +/- 231.min-1) when assessed on the TM, significant changes in these same parameters were not seen when assessed on the SAE. The importance of these results was discussed.

Adult↗

PubMed1990

Physiological capacities of individuals with cerebral palsy.

The physical work capacity (PWC) and the physiological response to stimulated tasks of nine ambulatory individuals with cerebral palsy (CP) were studied. Energy demand for each work task was determined by percentage of PWC (%PWC). Results demonstrated significant differences in energy demand attributed to frequency and mode of lift regardless of gender. No significant difference for energy demand, however, was seen for load lifted. The %PWC for several tasks was near or above the accepted limit for an eight-hour workday, suggesting that the subjects were performing close to their physical limits or higher and would possibly experience fatigue before the eight-hour workday ended. The results also indicated that the PWC of subjects in this study was inferior to that of their nondisabled peers.

Arousal↗

PubMed1990

Cardiorespiratory responses of mentally retarded adults to air-brake ergometry and treadmill exercise.

The graded treadmill (TM) exercise test is considered the optimal mode of exercise for evaluating the cardiovascular fitness of mentally retarded (MR) individuals. A new mode of exercise, the Schwinn Air-Dyne ergometer (SAE), was evaluated and compared to the TM for determining the cardiovascular fitness of adults. Twelve MR adults performed maximal exercise tests to volitional exhaustion, on separate days, on the SAE and TM. Maximal heart rates, oxygen consumption, minute ventilation, and respiratory quotient were similar for both exercise tests. These results indicate that the SAE is comparable to TM exercise in assessing the cardiovascular capacity of MR adults.

Adult↗

PubMed1990

A reliable isokinetic strength test for arm and leg musculature for mildly mentally retarded adults.

This study attempted to establish a reliable test protocol to measure the strength of muscles involved in elbow and knee flexion and extension for mentally retarded (MR) adults. Nineteen mildly MR adults performed strength tests on a Cybex 340 isokinetic dynamometer on two separate days; 12 subjects performed a third trial of knee flexion and extension tests. For the 19 subjects, there were no significant differences in strength measurements--except for peak torque of knee flexion--between the first two test days. There were relatively high correlation coefficients when test parameters were compared for both test days, and best efforts occurred almost as often on test day two as on test day one. For the 12 subjects tested on three test days, there were no significant differences for test parameters among the three test days; however, 25% of best efforts took place on test day three. These findings indicate that when measuring the isokinetic strength of mildly MR individuals, tests should be performed at least two, optimally three, separate times to ensure reliability. The test protocol would be reliable when measuring knee and elbow flexion and extension strength for job assessment or clinical or rehabilitation purposes.

Adult↗

PubMed1989

Stimulating somatic afferent fibers alters coronary arterial resistance.

We used a constant flow preparation to study the changes in left circumflex coronary arterial (LCCA) pressure and resistance evoked by electrical stimulation of branches of muscle, cutaneous, and mixed nerves in the hindlimb of anesthetized dogs. Stimulation (20 Hz) of all three nerve types at 20, 70, 100, and 200 times the voltage threshold that evoked compound action potentials significantly (P less than 0.05) increased LCCA resistance. Stimulation at three and five times threshold had no effect on this same variable. Cooling the nerve to 2-4 degrees C, temperatures that block myelinated nerve fibers, attenuated but did not abolish the increase in LCCA resistance. Combinations of beta- and alpha-adrenergic and cholinergic blockade established that the biphasic change evoked by nerve stimulation was due to an initial alpha-adrenergic vasoconstriction followed by a metabolite-induced vasodilation. These data demonstrate that stimulation of muscle, cutaneous, or mixed nerve afferent C-fibers increases coronary arterial resistance by alpha-adrenergic vasoconstriction.

Afferent Pathways↗

PubMed1989

Efficacy of exercise for end-stage renal disease patients immediately following high-efficiency hemodialysis: a pilot study.

Nine patients receiving maintenance high-efficiency hemodialysis were studied before and after a 12-week conditioning program to determine the efficacy of exercise immediately following hemodialysis. Each patient performed a combination of bicycle ergometry on the Schwinn Air-Dyne ergometer (SAE) and treadmill walking three times a week for a total exercise time of 15-35 min per session. A low-level Bruce treadmill test and an exercise test on the SAE were administered before and after training. Hematological, serum electrolyte, and serum lipid profiles were also determined before and after training. Following training, there were improvements in exercise capacities for both treadmill walking and ergometry on the SAE. Although a significant increase in serum apolipoprotein A1 was seen following exercise, no significant changes were observed for total cholesterol, low-density-lipoprotein cholesterol, high-density-lipoprotein cholesterol or apolipoprotein B. Additionally, no significant changes were seen in hematological parameters and serum electrolyte profiles following the exercise program. The 9 patients demonstrated an average compliance record of 74%. This study demonstrated that patients on high-efficiency hemodialysis can safely engage in an exercise program immediately following dialysis at intensities and frequencies that can improve their physical work capacities.

Aged↗

PubMed1988

Activation of gastric afferent fibers increases coronary arterial resistance in anesthetized dogs.

Stimulation of chemically sensitive receptors in the stomach with capsaicin is known to reflexly increase heart rate, arterial pressure, left ventricular contractility, and systemic vascular resistance. What is not known, however, is if activating these gastric afferents can also evoke reflex changes in coronary arterial resistance. Therefore, in 24 chloralose-anesthetized dogs, we used a Gregg cannula and a constant flow preparation to assess left circumflex coronary arterial (LCCA) resistance while stimulating chemically sensitive gastric receptors with capsaicin. Capsaicin (60 micrograms), applied topically to the serosal surface of the stomach, produced significant (P less than 0.05) increases in heart rate (8 +/- 2 bpm), mean arterial pressure (22 +/- 1 mm Hg), LCCA pressure (7 +/- 1 mm Hg), and LCCA resistance (0.30 +/- 0.04 mm Hg/ml/min). These responses were still present after bilateral thoracic vagotomy, but were eliminated by bilateral thoracic splanchnicotomy. alpha-adrenergic blockade eliminated and beta-adrenergic blockade enhanced the increases in LCCA pressure and resistance that were evoked by capsaicin. Thus, stimulating chemically sensitive receptors in the stomach can reflexly increase coronary arterial resistance by alpha-adrenergic vasoconstriction. The possibility exists, therefore, that physiological or pathological events which activate gastric afferents can affect reflexly the coronary circulation.

Administration, Topical↗

PubMed1987

Regional distribution of blood flow of dogs during graded dynamic exercise.

The regional blood flow response to progressive treadmill exercise was measured with radioactive microspheres in 25 untrained mongrel dogs. Incremental increases in work intensity resulted in corresponding increases in blood flows to the gracilis, gastrocnemius, semimembranosus, and semitendinosus muscles of the hindlimb and to the heart. During maximal exercise, blood flow was greatest in the semimembranosus muscle and lowest in the semitendinosus muscle (342 and 134 ml-1.100 g tissue-1.min-1, respectively). Exercise produced a decrease in blood flow to the temporalis muscle, which was classified as nonlocomotive in function. Blood flows to the stomach, pancreas, and large intestine decreased at the lowest exercise work load and remained diminished throughout the continuum to maximal exercise. Blood flows to the small intestine and spleen were maintained during submaximal exercise but were reduced by 50% at maximal O2 consumption (VO2max). No changes in blood flows to the kidneys, adrenal glands, liver, and brain were found. These results demonstrate that 1) renal blood flow is maintained at resting levels during exercise in untrained dogs; 2) blood flow changes in the various organs of the splanchnic region of dogs during exercise are heterogeneous; and 3) blood flows to the working skeletal muscles of dogs progressively increase with increasing work loads up to VO2max.

Animals↗

PubMed1987

Aerobic training exercises for individuals who had amputation of the lower limb.

The findings in ten subjects who had an amputation of the lower limb or limbs were studied before and after a fifteen-week aerobic conditioning program to determine if it improved cardiovascular fitness and reduced the effort of walking. Each subject exercised on an Air-Dyne ergometer (Schwinn, Chicago, Illinois) regularly during each week of the study period at 60 to 80 per cent of their estimated maximum heart rate. A test of maximum exercise on the ergometer and a test of walking on a treadmill were administered before and after training. After training, there was an increase of 25 per cent in the maximum capacity for exercise on the ergometer as well as significantly lower values for heart rate and consumption of oxygen during submaximum walking on the treadmill at various inclined grades. Aerobic conditioning was shown not only to improve cardiovascular fitness but also to increase the economy of walking in the subject who had an amputation of the lower limb or limbs.

Adult↗

PubMed1987

Maximal response of wheelchair-confined subjects to four types of arm exercise.

Maximal work capacity and aerobic fitness of wheelchair-confined subjects generally have been determined by one of three modes of exercise: wheelchair ergometry, wheelchair exercise on a treadmill (TM), and arm crank ergometry. In the present study, two new types of arm ergometers, the Cybex Upper Body Exercise ergometer (CUBE) and the Schwinn Air-Dyne ergometer (SAE), have been evaluated and compared with older methods for determining aerobic capacities of wheelchair-confined subjects. Seven persons with paraplegia with lesions ranging from T-3 to L-1 and one bilateral amputee each performed four exercise tests to volitional exhaustion, on separate days, utilizing four modes of exercise. These included wheelchair exercise on a treadmill and arm exercise using a Monark arm ergometer (MAE), a CUBE, or an SAE. Peak values for oxygen consumption, heart rate, and blood lactate were similar during each type of exercise. Significant (p less than 0.05) differences were observed only in the peak values for minute ventilation (CUBE greater than MAE, SAE greater than MAE). The similarity of the maximal responses observed in this study indicates that the CUBE and SAE are comparable to TM exercise and to the MAE in assessing the aerobic capacity of wheelchair-confined subjects.

Arm↗

PubMed1986

Stimulation of pulmonary C fibres decreases coronary arterial resistance in dogs.

A constant-flow preparation was used to assess coronary arterial resistance while activating pulmonary C fibres in chloralose-anaesthetized dogs. A Gregg cannula was passed through the left common carotid artery until the tip fitted snugly in the left circumflex coronary artery. The cannula was perfused with blood from the left femoral artery and blood flow through the cannula was maintained constant with a perfusion pump. Perfusion pressure in the coronary artery was measured from a side arm in the cannula, and resistance in that vessel was calculated as the ratio of pressure to blood flow. Capsaicin (10-20 micrograms/kg), injected into the right jugular vein, produced significant (P less than 0.05) decreases in heart rate, systemic arterial pressure, coronary arterial pressure and coronary arterial resistance. These responses were abolished by bilateral vagotomy. Neither left atrial injections of capsaicin nor acutely decreasing the systemic arterial pressure by occluding the inferior vena cava had a significant effect on the coronary arterial pressure or resistance. Additionally, overdrive pacing of the heart had no effect on the reflex decreases in coronary arterial pressure and resistance that were evoked when capsaicin was injected into the jugular vein. alpha-Adrenergic blockade reduced the reflex decrease in coronary arterial pressure and resistance evoked by capsaicin by 31 and 38%, respectively. Combined alpha-adrenergic and cholinergic blockade reduced the reflex decreases in both coronary arterial pressure and resistance by approximately 89%. These results indicate that activation of pulmonary C fibres produces a reflex decrease in coronary arterial resistance, and that this response is due to the combined effects of increased parasympathetic cholinergic activity and withdrawal of alpha-adrenergic tone.

Animals↗