Biomedical subjects

M T Hopman

Publications and source records attributed to M T Hopman.

At least 19 recordsLinked to original sources

PubMed2001

Reproducibility of contractile properties of the human paralysed and non-paralysed quadriceps muscle.

This study assessed the reproducibility of electrically evoked, isometric quadriceps contractile properties in eight people with spinal cord injury (SCI) and eight able-bodied (AB) individuals. Over all, the pooled coefficients of variation (CVps) in the SCI group were significantly lower (ranging from 0.03 to 0.15) than in the AB group (ranging from 0.08 to 0.21) (P<0.05). Furthermore, in all subjects, the variability of force production increased as stimulation frequency decreased (P<0.01). In subjects with SCI, variables of contractile speed are clearly less reproducible than tetanic tension or resistance to fatigue. Contractile properties of quadriceps muscles of SCI subjects were significantly different from that of AB subjects. Muscles of people with SCI were less fatigue resistant (P<0.05) and produced force-frequency relationships that were shifted to the left, compared with AB controls (P<.01). In addition, fusion of force responses resulting from 10 Hz stimulation was reduced (P<.05) and speed of contraction (but not relaxation) was increased (P<0.05), indicating an increased contractile speed in paralysed muscles compared with non-paralysed muscles. These results correspond with an expected predominance of fast glycolytic muscle fibres in paralysed muscles. It is concluded that quadriceps dynamometry is a useful technique to study muscle function in non-paralysed as well as in paralysed muscles. Furthermore, these techniques can be reliably used, for example, to assess therapeutic interventions on paralysed muscles provided that expected differences in relative tetanic tension and fatigue resistance are larger than approximately 5% and differences in contractile speed are larger than approximately 15%.

Adult↗

PubMed2001

Peripheral vascular changes after electrically stimulated cycle training in people with spinal cord injury.

OBJECTIVE: To test whether a short period of training leads to adaptations in the cross-sectional area of large conduit arteries and improved blood flow to the paralyzed legs of individuals with spinal cord injury (SCI). DESIGN: Before-after trial. SETTING: Rehabilitation center, academic medical center. PARTICIPANTS: Nine men with spinal cord lesions. INTERVENTION: Six weeks of cycling using a functional electrically stimulated leg cycle ergometer (FES-LCE). MAIN OUTCOME MEASURES: Longitudinal images and simultaneous velocity spectra were measured in the common carotid (CA) and femoral (FA) arteries using quantitative duplex Doppler ultrasound examination. Arterial diameters, peak systolic inflow volumes (PSIVs), mean inflow volumes (MIVs), and a velocity index (VI), representing the peripheral resistance, were obtained at rest. PSIVs and VI were obtained during 3 minutes of hyperemia following 20 minutes of FA occlusion. RESULTS: Training resulted in significant increases in diameter (p < .01), PSIVs (p < .01), and MIVs (p < .05), and reduced VI (p < .01) of the FA, whereas values in the CA remained unchanged. Postocclusive hyperemic responses were augmented, indicated by significantly higher PSIVs (p <.01) and a trend toward lower VI. CONCLUSION: Six weeks of FES-LCE training increased the cross-sectional area of large conduit arteries and improved blood flow to the paralyzed legs of individuals with SCI.

Adult↗

PubMed2001

Blood flow and muscle oxygen uptake at the onset and end of moderate and heavy dynamic forearm exercise.

We hypothesized that forearm blood flow (FBF) during moderate intensity dynamic exercise would meet the demands of the exercise and that postexercise FBF would quickly recover. In contrast, during heavy exercise, FBF would be inadequate causing a marked postexercise hyperemia and sustained increase in muscle oxygen uptake (VO(2musc)). Six subjects did forearm exercise (1-s contraction/relaxation, 1-s pause) for 5 min at 25 and 75% of peak workload. FBF was determined by Doppler ultrasound, and O(2) extraction was estimated from venous blood samples. In moderate exercise, FBF and VO(2musc) increased within 2 min to steady state. Rapid recovery to baseline suggested adequate O(2) supply during moderate exercise. In contrast, FBF was not adequate during heavy dynamic exercise. Immediately postexercise, there was an approximately 50% increase in FBF. Furthermore, we observed for the first time in the recovery period an increase in VO(2musc) above end-exercise values. During moderate exercise, O(2) supply met requirements, but with heavy forearm exercise, inadequate O(2) supply during exercise caused accumulation of a large O(2) deficit that was repaid during recovery.

Adult↗

PubMed2001

Changes in cerebral oxygenation and blood flow during LBNP in spinal cord-injured individuals.

Spinal cord-injured (SCI) individuals, having a sympathetic nervous system lesion, experience hypotension during sitting and standing. Surprisingly, they experience few syncopal events. This suggests adaptations in cerebrovascular regulation. Therefore, changes in systemic circulation, cerebral blood flow, and oxygenation in eight SCI individuals were compared with eight able-bodied (AB) individuals. Systemic circulation was manipulated by lower body negative pressure at several levels down to -60 mmHg. At each level, we measured steady-state blood pressure, changes in cerebral blood velocity with transcranial Doppler, and cerebral oxygenation using near-infrared spectroscopy. We found that mean arterial pressure decreased significantly in SCI but not in AB individuals, in accordance with the sympathetic impairment in the SCI group. Cerebral blood flow velocity decreased during orthostatic stress in both groups, but this decrease was significantly greater in SCI individuals. Cerebral oxygenation decreased in both groups, with a tendency to a greater decrease in SCI individuals. Thus present data do not support an advantageous mechanism during orthostatic stress in the cerebrovascular regulation of SCI individuals.

Adult↗

PubMed2000

Sympathetic nervous system activity and cardiovascular homeostatis during head-up tilt in patients with spinal cord injuries.

The relationship between sympathetic nervous system activity and cardiovascular responses to head-up tilt in patients with spinal cord injuries and in able-bodied subjects was studied. Twenty-seven adults, nine in each of the three groups (tetraplegia, paraplegia, and able-bodied subjects) were tilted 70 degrees, head up, for 12 minutes after 20 minutes supine rest. Differences between steady-state measurements of mean arterial pressure, stroke volume, and sympathetic nervous system activity were estimated in both positions. Sympathetic nervous system activity was reflected by the low-frequency peak of the blood pressure variability spectrum. From supine rest to head-up tilt, low-frequency power increased in able-bodied subjects (median, 0.42 mm Hg2, p = 0.003), which was different (p = 0.015) from patients with tetraplegia and paraplegia (-0.15 and -0.10 mm Hg2, respectively). Stroke volume and mean arterial pressure decreased in patients with tetraplegia (-40% and -9 mm Hg, respectively; p = 0.008, both variables) more than in able-bodied subjects (-33%, 11 mm Hg, respectively) or patients with paraplegia (-24%, 8 mm Hg, respectively). Results indicated increased sympathetic nervous system activity during head-up tilt in able-bodied subjects, but not in patients with paraplegia or tetraplegia, whereas patients with tetraplegia, but not paraplegia, showed poorer cardiovascular homeostasis than able-bodied subjects. This suggests that patients with paraplegia maintained cardiovascular homeostasis during head-up tilt without increased sympathetic nervous system activity.

Adult↗

PubMed2000

The effect of electrical stimulation on leg muscle pump activity in spinal cord-injured and able-bodied individuals.

The purpose of this study was to examine the difference in: (1) effective muscle pump activity (MPA) between voluntary and electrically (ES) induced contractions in able-bodied subjects (ABS); and (2) ES-induced MPA between spinal cord-injured (SCI) individuals and ABS. MPA was measured as relative volume changes in the calf using strain-gauge plethysmography during repeated muscle contractions in the supine position while venous outflow was impeded by a thigh cuff inflated to a range of pressures. Ten SCI individuals and ten ABS participated in this study. ABS showed no significant difference between voluntary and electrically induced MPA [58.1 (18.4)% versus 67.7 (8.7)%, respectively]. SCI individuals showed a significantly lower ES-induced MPA than ABS [21.5 (15.9)% versus 67.7 (8.7)%, respectively]. The low MPA in SCI individuals may be explained by: (1) extensive leg muscle atrophy and/or (2) an "atrophic" vascular system in the legs. The electrical current level seemed to influence MPA (43 mA, 21.5% versus 60 mA, 30.8%) for SCI individuals, whereas no influence of muscle contraction rate on MPA was observed in ABS. The results of this study demonstrate that although ES-induced leg muscle contractions result in adequate MPA in ABS, it leads to significantly less effective MPA in SCI individuals.

Adult↗

PubMed2000

Systemic circulation and cerebral oxygenation during head-up tilt in spinal cord injured individuals.

OBJECTIVE: To compare tilt-induced alterations in cardiovascular homeostasis and cerebral oxygenation of spinal cord-injured (SCI) to able-bodied (AB) individuals. DESIGN: Subjects underwent 10 min supine rest followed by 10 min 70 degrees head-up tilt. The last 5 min of supine rest and head-up tilt were analyzed, provided a steady state existed. SUBJECTS: SCI individuals (n= 11), with lesions between C4 and T4, and AB individuals (n= 10), all males and balanced for age and weight. MAIN OUTCOME MEASURES: Calf circumference, mean arterial pressure (MAP), stroke volume, heart rate and cerebral oxygenated ([O2Hb]), deoxygenated ([HHb]) and total ([tHb]) haemoglobin concentration changes were measured. RESULTS: Head-up tilt evoked a greater fall in MAP (mean (SD): -9 (12) vs 2 (6) mmHg P=0.02) and stroke volume (-43 (12) vs -22 (10)%, P=0.005), and a greater increase in heart rate (27 (12) vs 18 (6) beats, P=0.04) in SCI than AB. Cardiac output decreased during head-up tilt in SCI but not in AB (-17 (15) vs 1 (15)%, P=0.01). The change in cerebral oxygenation ([HHb]: 3.9 (2.8) vs 2.8 (1.4) micromol x l(-1), P=0.1 and [O2Hb]: -6.1 (5.0) vs -2.1 (5.5) micromol x l(-1), P=0.1) was similar in SCI and AB. All variables mentioned showed a change significantly different from zero in both groups, apart from [O2Hb] in AB and [tHb] in both groups. CONCLUSION: SCI demonstrated a greater decrease of MAP and stroke volume with a similar decrease in cerebral oxygenation compared to AB. This suggests that although systemic circulation was less well regulated in SCI compared with AB, cerebral circulation in SCI was maintained as in AB.

Adult↗

PubMed2000

Altered contractile properties of the quadriceps muscle in people with spinal cord injury following functional electrical stimulated cycle training.

STUDY DESIGN: A longitudinal training study. OBJECTIVES: To assess if contractile speed and fatigability of paralysed quadriceps muscles in individuals with spinal cord injury (SCI) can be altered by functional electrical stimulation leg cycle ergometry (FES-LCE) training. SETTINGS: The Sint Maartenskliniek rehabilitation centre and the University of Nijmegen, Nijmegen, the Netherlands. METHODS: Contractile properties of the quadriceps muscle were studied in seven people with motor-complete SCI who participated in a FES-LCE training program. Subjects trained for 30 min, three times per week for 6 weeks. Contractile speed and fatigue characteristics of electrically stimulated isometric contractions were compared before and after 6 weeks of FES-LCE. RESULTS: Fatigue resistance improved following FES-LCE training as indicated by the higher forces maintained in response to repetitive electrical stimulation. In contrast with an improved fatigue resistance, the maximal rate of force rise was unaffected, the speed of relaxation increased and the fusion of a 10 Hz force signal decreased. Furthermore, the force-frequency relationship shifted to the right at low stimulation frequencies, indicated by a decline in the ratio of 1 and 100 Hz force responses as well as the ratio of 10 and 100 Hz force responses. CONCLUSION: FES-LCE training can change the physiological properties of the quadriceps muscle in people with SCI. Even after a short period of training, the stimulated muscles become more resistant to fatigue. Furthermore, the increased speed of relaxation and associated decreased fusion and altered force-frequency relationship following training may be related to adaptations in the calcium handling processes, which reflect an early response of long-term disused muscles.

Adult↗

PubMed2000

Influence of muscle temperature on the contractile properties of the quadriceps muscle in humans with spinal cord injury.

Low muscle temperature in paralysed muscles of individuals with spinal cord injury may affect the contractile properties of these muscles. The present study was therefore undertaken to assess the effects of increased muscle temperature on the isometric contractile properties of electrically stimulated paralysed quadriceps muscles. When muscle temperature at a depth of 3 cm was increased from approximately 32 degrees C to approximately 36 degrees C by ultra-short-wave application, the half-relaxation time shortened and low-frequency force responses became less fused, but the maximal rate of increase in force remained unchanged. Heating had no effect upon either force decline or slowing of relaxation during fatiguing contractions. The force-frequency relationship of the paralysed quadriceps muscle was shifted to the right after the muscle was heated. Despite this shift, however, the relationship still resembled that in muscles of non-paralysed individuals, probably due to the unexplained high twitch forces. These results indicate that reduced muscle temperature in spinal-cord-injured individuals may lead to an underestimation of the changes in contractile properties in terms of relaxation rate or the degree of fusion with low-frequency stimulation. In addition, the force-frequency relationship of paralysed muscles does not accurately reflect the magnitude of these changes, even when the muscle is heated, and should therefore be treated with caution.

Adult↗

PubMed1999

Contractile properties of the quadriceps muscle in individuals with spinal cord injury.

Selected contractile properties and fatigability of the quadriceps muscle were studied in seven spinal cord-injured (SCI) and 13 able-bodied control (control) individuals. The SCI muscles demonstrated faster rates of contraction and relaxation than did control muscles and extremely large force oscillation amplitudes in the 10-Hz signal (65 +/- 22% in SCI versus 23 +/- 8% in controls). In addition, force loss and slowing of relaxation following repeated fatiguing contractions were greater in SCI compared with controls. The faster contractile properties and greater fatigability of the SCI muscles are in agreement with a characteristic predominance of fast glycolytic muscle fibers. Unexpectedly, the SCI muscles exhibited a force-frequency relationship shifted to the left, most likely as the result of relatively large twitch amplitudes. The results indicate that the contractile properties of large human locomotory muscles can be characterized using the approach described and that the transformation to faster properties consequent upon changes in contractile protein expression following SCI can be assessed. These measurements may be useful to optimize stimulation characteristics for functional electrical stimulation and to monitor training effects induced by electrical stimulation during rehabilitation of paralyzed muscles.

Adult↗

PubMed1999

Non-invasive assessment of autonomic nervous system integrity in able-bodied and spinal cord-injured individuals.

The purpose of this study is to identify features of the Valsalva maneuver (VM) that differentiate between able-bodied (AB, n = 14) and spinal cord-injured individuals with high (T, n = 11) and low (P, n = 10) lesions. The systolic blood pressure (BP) recovery during the VM was used as a measure of sympathetic and vagal activity, whereas from the BP rise in phase IV of the VM baroreflex sensitivity was derived. After a similar initial BP decrease in all groups, BP recovered faster and more completely in AB compared to P and T during the VM. After release of the VM, the BP overshoot was very similar in AB and P, suggesting that the BP overshoot reflects sympathetic activity onto the heart. The baroreflex sensitivity was smaller in P, but not in T, compared to AB. However, 36% of the observations of T had such a low correlation between BP and RR interval that a slope could not be determined, which caused loss of observations, but suggested a low baroreflex sensitivity as well.

Adult↗

PubMed1999

Effect of a pulsating anti-gravity suit on peak exercise performance in individual with spinal cord injuries.

The aim of this study was to examine effects of a pulsating pressure anti-gravity suit on the peak values of oxygen uptake (VO2) and power during maximal arm exercise in spinal-cord-injured (SCI) individuals. Five well-trained SCI men (with lesions at levels between T6 and L1) and seven well-trained able-bodied men (ABC) performed two incremental (10 W x min(-1)) arm-cranking tests. During one test the pressure in the anti-G suit pulsated between 4.7 kPa (35 mmHg) and 9.3 kPa (70 mmHg) every 2 s (PPG+), during the other test (PPG-) all the subjects wore the anti-G suit in a deflated state. Tests were performed in a counter-balanced order. Peak VO2 in SCI was 1 ml x kg(-1) x min(-1) lower during PPG+ compared to PPG- (P = 0.05). Peak power and peak heart rate were not significantly different during PPG+ compared to PPG-. These results would suggest that no increase in work capacity can be obtained with a pulsating pressure anti-gravity suit in either SCI or ABC.

Adult↗

PubMed1999

Training of the respiratory muscles in individuals with tetraplegia.

STUDY DESIGN: An experimental cross-sectional design. OBJECTIVES: To evaluate whether training of the innervated respiratory muscles in individuals with a (partial) cervical spinal cord injury will improve the strength and endurance capacity of these muscles and the exercise performance in these individuals. SETTING: Department of Physiology and Pulmonary diseases, Nijmegen, The Netherlands. METHOD: In this study nine individuals with tetraplegia (C3 C7) performed a target flow endurance training of the inspiratory muscles, twice a day for 15 min. First, the subjects performed a 'sham' training for 6 weeks with no appreciable resistance, after that they performed a 'real' training for 6 weeks with a resistance of 70% of the maximal endurance capacity of the inspiratory muscles. The training was evaluated at 0, 6 and 12 weeks by the following tests: (1) the slow Inspiratory Vital Capacity (IVC) and the Forced Inspiratory and Expiratory Volumes over 1 s (FIV1 and FEV1); (2) the Maximal Inspiratory Mouth Pressure (Pimax) and the Endurance Pressure (Pendu) and (3) a maximal arm-cranking exercise test. RESULTS: After the sham training, the Pendu was increased from 3.98 to 4.71 kPa with a P-value of 0.05. The sham training had no influence on any of the other variables. The real training had no effect on the IVC, FIV1, FEV1 and Pimax, however, increased the Pendu from 4.71 to 6.16 kPa (P=0.01), representing the respiratory muscle-endurance capacity. The oxygen consumption (VO2 peak) in the maximal exercise test improved from 0.87 to 0.98 l/min (P = 0.05). CONCLUSION: The results of the study indicate that training of the respiratory muscles results in an enhanced endurance capacity of these muscles and a concomitant increase in the aerobic exercise performance.

Adult↗

PubMed1999

Reproducibility of the alterations in circulation and cerebral oxygenation from supine rest to head-up tilt.

Cardiovascular stability, as affected by several diseases, may be assessed by head-up tilt testing. Follow-up studies are essential in both evaluating interventions and assessing progression. However, data on the reproducibility of the changes in circulatory status and cerebral oxygenation provoked by head-up tilt testing are fundamental to follow-up studies. The aim of this study was, therefore, to assess the reproducibility of the alterations in stroke volume (SV), mean arterial pressure (MAP), as well as oxygenated ([O2Hb]) and deoxygenated haemoglobin ([HHb]) concentration in cerebral tissue from supine rest (SUP) to head-up tilt (HUT). SV was calculated by Modelflow, a pulse contour method, from the finger arterial pressure wave measured by Portapres, the portable version of Finapres. [O2Hb] and [HHb] were measured using near-infrared spectroscopy (NIRS). Ten healthy individuals visited the laboratory on two different days. On both days, they underwent 10 min SUP followed by 10 min 70 degrees HUT twice. SV decreased, which was (in part) compensated for by an increased heart rate, while MAP increased slightly during HUT compared with SUP. Although [HHb] increased during HUT, no presyncope symptoms were experienced. The circulatory variables (SV, HR and MAP) as well as [HHb] showed an acceptably small systematic and random error as well as reproducibility error compared with the observed difference between HUT and SUP and were similar between and within visits. Therefore, it is concluded that MAP measured by Portapres and SV calculated by Modelflow as well as HHb measured by NIRS seem to be reproducible and may therefore be used in follow-up studies.

Adult↗

PubMed1999

Non-invasive cardiac output assessment during moderate exercise: pulse contour compared with CO2 rebreathing.

The arterial pulse contour method called Modelflow 2.1 calculates stroke volume continuously, beat to beat, from the non-invasive blood pressure signal measured by Finapres or Portapres. Portapres is the portable version of Finapres. The purpose of this study was to compare cardiac output (CO) calculated using Modelflow 2.1 (COmf) with CO obtained by the CO2 rebreathing method (COre) during steady state at moderate exercise levels. Twelve subjects visited the laboratory twice and performed submaximal exercise on a bicycle ergometer at 20%, 40% and 60% of their individual peak power output (POpeak). The averaged correlation between COmf and COre gives an r-value of 0.69, whereas the slope and intercept of the regression line were 1.06 and 1.65 respectively. The averaged difference between COmf and COre was 2.27 +/- 3.91 min-1 (mean +/- standard deviation). However, the test-retest difference between COmf and COre was 2.5 +/- 3.1 and 0.5 +/- 1.31 min-1 respectively. These results suggest that Modelflow 2.1 is not an accurate method for estimating CO from non-invasive blood pressure data collected by Portapres during exercise at up to 60% of the individual POpeak corresponding with daily life activity.

Adult↗

PubMed1998

Limits to maximal performance in individuals with spinal cord injury.

The purpose of this study was to examine the effect of four conditions that might improve oxygen transport and/or utilization during maximal exercise performance in individuals with spinal cord injury (SCI). Five males with tetraplegia (TP) and four males with paraplegia (PR) performed maximal arm cranking exercise in the following positions: 1) sitting; 2) supine; and 3) sitting with the addition of a) anti-gravity suit (anit-G), b) elastic stockings and abdominal binder, and c) functional electrical stimulation (FES) of the paralysed leg muscles. Peak power output (PO peak), peak oxygen uptake (VO2peak), peak heart rate (HR peak) and maximal systolic blood pressure were significantly lower in TP compared to PR for all conditions. A significant decrease in HR peak for PR, and a significant increase in VO2peak/kg for TP was seen during the supine compared to sitting condition. Respiratory exchange ratio (R) decreased significantly during the FES compared to the sitting condition in TP. No other changes were observed for any of the other conditions in either group. Improvements in central circulation previously reported during submaximal exercise for these four conditions did not result in a concomitant rise in maximal exercise performance. The results of this study suggest that the limitation in VO2peak for individuals with SCI is located peripherally (small active muscle mass) rather than centrally (heart or lungs).

Abdomen↗

PubMed1998

Blood redistribution and circulatory responses to submaximal arm exercise in persons with spinal cord injury.

The purpose of this study was to evaluate responses to submaximal arm exercise (20%, 40%, and 60% of peak power output) using four conditions to support the circulatory redistribution in persons with spinal cord injury (SCI). Five males with tetraplegia (TP) and four males with paraplegia (PR) exercised 1) sitting, 2) supine, and 3) sitting with the addition of a) an anti-gravity suit (anti-G), b) elastic stockings and abdominal binder, and c) functional electrical stimulation of the leg muscles. Compared to sitting, the following significant changes were observed: in the supine position, heart rate (HR) decreased (PR: 104 vs 118 b/min, TP: 76 vs 92 b/min) and stroke volume (SV) increased (PR: 132 vs 116 ml, TP: 96 vs 83 ml). The anti-G suit induced a decrease in heart rate (PR: 104 vs 118 b/min, TP: 87 vs 92 b/min) and a decrease in oxygen uptake (VO2) in PR. Stockings only affected TP, i.e. a decrease in heart rate with 5 b/min and an increase in stroke volume with 13 ml/beat. Functional electrical stimulation produced an increase in VO2 (PR: 1.00 vs 0.95 l/min, TP: 0.68 vs 0.53 l/min) and a rise in stroke volume in TP. Results indicate that the methods employed to support the circulatory redistribution have different working mechanisms and, in addition, that the effects are different for TP and PR probably because of differences in active muscle mass, sympathetic impairment and blood pressure values.

Adult↗

PubMed1997

Near infrared spectroscopy for noninvasive assessment of claudication.

The purpose of this study was to explore the application of near-infrared spectroscopy (NIRS) to the assessment of peripheral arterial occlusive disease (PAOD). Muscle blood flow, oxygen consumption, arterial inflow capacity, O2 resaturation, and recovery times were determined at rest, under ischemic and hyperemic conditions, and continuously during and after walking exercise in 11 claudicants and 15 nonclaudicants. Blood flow and oxygen consumption (VO2) at rest and blood flow following walking exercise did not differ significantly between claudicants and nonclaudicants. In contrast, VO2 after walking exercise was increased by a factor 4.1 in claudicants compared to a factor of 1.7 in nonclaudicants. The oxygen resaturation rate after arterial occlusion and the oxygen resaturation rate after walking exercise were significantly lower in claudicants. Claudicants showed a higher degree of hemoglobin deoxygenation during walking exercise than nonclaudicants. A high postexercise VO2 is correlated with a low ankle-branchial index (ABI). The resaturation rates and recovery times following walking exercise and arterial occlusion correlated significantly with ABI parameters. A significant negative correlation was found between hemoglobin deoxygenation during exercise and the ABI parameters. A high correlation was observed between the oxygenated hemoglobin (O2Hb) recovery time and the ABI recovery time after walking exercise. NIRS appears to be an effective noninvasive method for assessing the imbalance between oxygen demand and oxygen delivery in the leg muscles of PAOD patients at rest and during exercise.

Adult↗