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PubMed2002

Attenuated sympathetic nerve responses after 24 hours of bed rest.

Bed rest reduces orthostatic tolerance. Despite decades of study, the cause of this phenomenon remains unclear. In this report we examined hemodynamic and sympathetic nerve responses to graded lower body negative pressure (LBNP) before and after 24 h of bed rest. LBNP allows for baroreceptor disengagement in a graded fashion. We measured heart rate (HR), cardiac output (HR x stroke volume obtained by echo Doppler), and muscle sympathetic nerve activity (MSNA) during a progressive and graded LBNP paradigm. Negative pressure was increased by 10 mmHg every 3 min until presyncope or completion of -60 mmHg. After bed rest, LBNP tolerance was reduced in 11 of 13 subjects (P <.023), HR was greater (P <.002), cardiac output was unchanged, and the ability to augment MSNA at high levels of LBNP was reduced (rate of rise for 30- to 60-mmHg LBNP before bed rest 0.073 bursts x min(-1) x mmHg(-1); after bed rest 0.035 bursts x min(-1) x mmHg(-1); P < 0.016). These findings suggest that 24 h of bed rest reduces sympathetic nerve responses to LBNP.

Adult↗
PubMed1993

Dependence of cardiac filling pressure on cardiac output during rest and dynamic exercise in dogs.

At rest, central venous pressure (CVP) falls when cardiac output (CO) rises. This can be attributed to flow-dependent redistribution of blood volume from central to peripheral blood vessels. In contrast, CVP rises during dynamic exercise despite a rise in CO. Therefore peripheral circulatory changes during exercise must counteract the factors that lower CVP when CO rises during rest. Our objectives were to determine the importance of blood flow, the muscle pump, and reflexes on changes in ventricular filling pressure during dynamic exercise. In seven dogs with a surgically produced atrioventricular (AV) block, normal relationships between CO and CVP were established by AV-linked pacing (normal heart rates) during rest and exercise. Cardiac output was altered during rest and treadmill exercise (4 miles/h at 0, 10, or 20% grade) by changing ventricular pacing rate to establish curves relating delta CVP to delta CO. These curves were displaced rightward (higher CO) and upward (higher CVP) by exercise because of the muscle pump. Changing CO by pacing during rest and exercise revealed a constant slope for delta CVP/delta CO of -2.7 mmHg.l-1.min-1. Blockade of reflex vasoconstriction and venoconstriction with hexamethonium at rest and during mild exercise (to isolate effects of the muscle pump) did not alter these slopes or the displacement of the curves by exercise, although CVP was 4.3 mmHg lower at a given CO after blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

High correlation of fractals for regional blood flows among resting and exercising skeletal muscles.

The regional blood flow distributions within single skeletal muscles are markedly uneven both at rest and during exercise hyperemia. Fractals adequately describe this perfusion heterogeneity in the resting lateral head of the gastrocnemius muscle as well as in the myocardium. Recently, we provided evidence that the fractal dimension for the blood flow distributions in this resting muscle was strongly correlated with that of the myocardium in the same rabbit. Prompted by this hitherto unknown observation, we have now examined 1) whether fractals also describe perfusion distributions within muscles with a varying metabolic activity, and 2) whether the fractal dimensions for blood flow distributions to these muscles were correlated. We used pentobarbital-anesthetized rabbits and cats. The regional distributions of blood flow within various skeletal muscles were estimated by microsphere trapping. The data unequivocally showed that the perfusion distributions could be described with fractals both in resting and in exercising muscle in both species, the corresponding fractal dimensions ranging from 1.36 to 1.41. The fractal dimensions were markedly correlated (r2 ranged from 0.82 to 0.88) when both various resting and resting plus exercising muscles were compared in the same animal. This surprising finding of high correlations for the fractal dimensions among various muscles within one animal provides a novel characteristic of blood flow heterogeneity.

Animals↗
PubMed1996

Reloading of Ca(2+)-depleted sarcoplasmic reticulum during rest in guinea pig ventricular myocytes.

The effects of rest on a Ca(2+)-depleted sarcoplasmic reticulum (SR) in guinea pig ventricular myocytes were investigated. Cell shortening was measured using a video edge-detection system, and cytoplasmic Ca2+ was monitored using the fluorescent indicator indo-1. Rapid cooling and rewarming in the presence of 10 mM caffeine were used to deplete the SR of Ca2+. The resting cell was then superfused for variable time intervals with a normal Tyrode solution containing 2 mM Ca2+. Another rapid cooling in caffeine was performed to assess the SR Ca2+ load at the end of rest. Rapid cooling after 1- and 2-min rest elicited an increase of indo-1 fluorescence of 51.9 +/- 7.7 (n = 17) and 72.7 +/- 6.7% of control (n = 9), respectively. This increase was not detectable when Ca2+ was absent from the superfusing solution. In contrast, the increase was larger when external Ca2+ was elevated to 4 mM. Nickel (5 mM) and nifedipine (20 microM) added to the superfusing solution during the rest interval did not alter the increase in indo-1 fluorescence. We conclude that Ca2+ is reaccumulated by a depleted SR during rest. Although this Ca2+ seems to originate from the extracellular space, its route from there to the SR is unclear.

Animals↗
PubMed2001

Regulation of muscle sympathetic nerve activity after bed rest deconditioning.

Cardiovascular deconditioning reduces orthostatic tolerance. To determine whether changes in autonomic function might produce this effect, we developed stimulus-response curves relating limb vascular resistance, muscle sympathetic nerve activity (MSNA), and pulmonary capillary wedge pressure (PCWP) with seven subjects before and after 18 days of -6 degrees head-down bed rest. Both lower body negative pressure (LBNP; -15 and -30 mmHg) and rapid saline infusion (15 and 30 ml/kg body wt) were used to produce a wide variation in PCWP. Orthostatic tolerance was assessed with graded LBNP to presyncope. Bed rest reduced LBNP tolerance from 23.9 +/- 2.1 to 21.2 +/- 1.5 min, respectively (means +/- SE, P = 0.02). The MSNA-PCWP relationship was unchanged after bed rest, though at any stage of the LBNP protocol PCWP was lower, and MSNA was greater. Thus bed rest deconditioning produced hypovolemia, causing a shift in operating point on the stimulus-response curve. The relationship between limb vascular resistance and MSNA was not significantly altered after bed rest. We conclude that bed rest deconditioning does not alter reflex control of MSNA, but may produce orthostatic intolerance through a combination of hypovolemia and cardiac atrophy.

Adolescent↗
PubMed1985

Epinephrine, norepinephrine, and dopamine during a 4-day head-down bed rest.

Head-down bed rest at an angle of 6 degrees was used as an experimental model to simulate the hemodynamic effects of microgravity, i.e., the shift of fluids from the lower to the upper part of the body. The sympathoadrenal activity during acute (from 0.5 to 10 h) and prolonged (4 days) head-down bed rest was assessed in eight healthy men (24 +/- 1 yr) by measuring epinephrine (E), norepinephrine (NE), dopamine (DA), and methoxylated metabolite levels in their plasma and urine. Catecholamine (CA) and methoxyamine levels were essentially unaltered at any time of bed rest. Maximal changes in plasma were on the second day (D2): NE, 547 +/- 84 vs. 384 +/- 55 pg/ml; DA, 192 +/- 32 vs. 141 +/- 16 pg/ml; NS. After 24 h of bed rest, heart rate decreased from 71 +/- 1 to 63 +/- 3/min (P less than 0.01). Daily dynamic leg exercise [50% maximum O2 uptake (VO2 max)] used as a countermeasure did not alter the pattern of plasma CA during bed rest but resulted in a higher urinary NE excretion during postexercise recovery (+45% on D2; P less than 0.05). The data indicate no evident relationship between sympathoadrenal function and stimulation of cardiopulmonary receptors or neuroendocrine changes induced by central hypervolemia during head-down bed rest.

Adult↗
PubMed1986

Effect of prolonged bed rest on lung volume in normal individuals.

Pulmonary function was assessed in supine subjects before, during, and after three separate bed-rest studies of 11 and 12 days duration. Forced vital capacity (FVC) increased during bed rest in each subject. Total lung capacity (TLC) was measured by helium dilution in one bed-rest study and increased in each subject, while residual volume and functional residual capacity of the respiratory system did not change. No change in FVC was found in an ambulatory control group using identical measurement techniques. Maintaining base-line plasma volume during one bed rest by the use of exogenous estrogen did not prevent an increase in FVC, and decreasing plasma volume with diuretics in ambulatory subjects to the same degree as seen in the bed rests did not cause an increase in FVC. We conclude that prolonged bed rest results in a small significant increase in TLC and that this change is not dependent on alterations in plasma volume.

Adult↗
PubMed1997

Resistance exercise maintains skeletal muscle protein synthesis during bed rest.

Spaceflight results in a loss of lean body mass and muscular strength. A ground-based model for microgravity, bed rest, results in a loss of lean body mass due to a decrease in muscle protein synthesis (MPS). Resistance training is suggested as a proposed countermeasure for spaceflight-induced atrophy because it is known to increase both MPS and skeletal muscle strength. We therefore hypothesized that scheduled resistance training throughout bed rest would ameliorate the decrease in MPS. Two groups of healthy volunteers were studied during 14 days of simulated microgravity. One group adhered to strict bed rest (BR; n = 5), whereas a second group engaged in leg resistance exercise every other day throughout bed rest (BREx; n = 6). MPS was determined directly by the incorporation of infused L-[ring-13C6] phenylalanine into vastus lateralis protein. After 14 days of bed rest, MPS in the BREx group did not change and was significantly greater than in the BR group. Thus moderate-resistance exercise can counteract the decrease in MPS during bed rest.

Adult↗
PubMed2000

Supine lower body negative pressure exercise during bed rest maintains upright exercise capacity.

Bed rest and spaceflight reduce exercise fitness. Supine lower body negative pressure (LBNP) treadmill exercise provides integrated cardiovascular and musculoskeletal stimulation similar to that imposed by upright exercise in Earth gravity. We hypothesized that 40 min of supine exercise per day in a LBNP chamber at 1.0-1.2 body wt (58 +/- 2 mmHg LBNP) maintains aerobic fitness and sprint speed during 15 days of 6 degrees head-down bed rest (simulated microgravity). Seven male subjects underwent two such bed-rest studies in random order: one as a control study (no exercise) and one with daily supine LBNP treadmill exercise. After controlled bed-rest, time to exhaustion during an upright treadmill exercise test decreased 10%, peak oxygen consumption during the test decreased 14%, and sprint speed decreased 16% (all P < 0.05). Supine LBNP exercise during bed rest maintained all the above variables at pre-bed-rest levels. Our findings support further evaluation of LBNP exercise as a countermeasure against long-term microgravity-induced deconditioning.

Adult↗
PubMed2004

Suppressing lipolysis increases interleukin-6 at rest and during prolonged moderate-intensity exercise in humans.

IL-6 induces lipolysis when administered to humans. Consequently, it has been hypothesized that IL-6 is released from skeletal muscle during exercise to act in a "hormonelike" manner and increase lipolysis from adipose tissue to supply the muscle with substrate. In the present study, we hypothesized that suppressing lipolysis, and subsequent free fatty acid (FFA) availability, would result in a compensatory elevation in IL-6 at rest and during exercise. First, we had five healthy men ingest nicotinic acid (NA) at 30-min intervals for 120 min at rest [10 mg/kg body mass (initial dose), 5 mg/kg body mass (subsequent doses)]. Plasma was collected and analyzed for FFA and IL-6. After 120 min, plasma FFA concentration was attenuated (0 min: 0.26 +/- 0.05 mmol/l; 120 min: 0.09 +/- 0.02 mmol/l; P < 0.01), whereas plasma IL-6 was concomitantly increased approximately eightfold (0 min: 0.75 +/- 0.18 pg/ml; 120 min: 6.05 +/- 0.89 pg/ml; P < 0.001). To assess the effect of lipolytic suppression on the exercise-induced IL-6 response, seven active, but not specifically trained, men performed two experimental exercise trials with (NA) or without [control (Con)] NA ingestion 60 min before (10 mg/kg body mass) and throughout (5 mg/kg body mass every 30 min) exercise. Blood samples were obtained before ingestion, 60 min after ingestion, and throughout 180 min of cycling exercise at 62 +/- 5% of maximal oxygen consumption. IL-6 gene expression, in muscle and adipose tissue sampled at 0, 90, and 180 min, was determined by using semiquantitative real-time PCR. IL-6 mRNA increased in Con (rest vs. 180 min; P < 0.01) approximately 13-fold in muscle and approximately 42-fold in fat with exercise. NA increased (rest vs. 180 min; P < 0.01) IL-6 mRNA 34-fold in muscle, but the treatment effect was not statistically significant (Con vs. NA, P = 0.1), and 235-fold in fat (Con vs. NA, P < 0.01). Consistent with the study at rest, NA completely suppressed plasma FFA (180 min: Con, 1.42 +/- 0.07 mmol/l; NA, 0.10 +/- 0.01 mmol/l; P < 0.001) and increased plasma IL-6 (180 min: Con, 9.81 +/- 0.98 pg/ml; NA, 19.23 +/- 2.50 pg/ml; P < 0.05) during exercise. In conclusion, these data demonstrate that circulating IL-6 is markedly elevated at rest and during prolonged moderate-intensity exercise when lipolysis is suppressed.

Adipose Tissue↗
PubMed2006

Tendon collagen synthesis at rest and after exercise in women.

In general, there is a higher incidence of musculoskeletal injuries during physical activity in women than in men. We hypothesized that in women rates of tendon collagen synthesis would be lower than in men at rest and after exercise, especially in the later luteal phase when estrogen and progesterone concentrations are higher than the early follicular phase. We studied tendon collagen fractional synthesis rate (FSR) in 15 young, healthy female subjects in either the early follicular (n = 8) or the late luteal phase (n = 7) 72 h after an acute bout of one-legged exercise (60 min kicking at 67% workload maximum) (72 h) and compared the results with those previously obtained for men. Samples were taken from the patellar tendon in both the exercised and rested legs to determine collagen FSR by the incorporation of [15N]proline into tendon collagen hydroxyproline. There was no effect of menstrual phase on tendon collagen synthesis either at rest or after exercise. However, there was a significant difference between women and men at rest (women = 0.025 +/- 0.002%/h, men = 0.045 +/- 0.008%/h; P < 0.05) and 72 h after exercise (women = 0.027 +/- 0.005%/h; men = 0.058 +/- 0.008%/h). Furthermore, rest and 72-h tendon collagen synthesis were not different in women, whereas in men tendon collagen synthesis remained significantly elevated 72 h after exercise. It is concluded that both in the resting state and after exercise, tendon collagen FSR is lower in women than in men, which may contribute to a lower rate of tissue repair after exercise.

Adult↗
PubMed2002

Carotid baroreflex control of leg vascular conductance at rest and during exercise.

We sought to test the hypothesis that the carotid baroreflex (CBR) alters mean leg blood flow (LBF) and leg vascular conductance (LVC) at rest and during exercise. In seven men and one woman, 25 +/- 2 (SE) yr of age, CBR control of LBF and LVC was determined at rest and during steady-state one-legged knee extension exercise at approximately 65% peak O(2) uptake. The application of 5-s pulses of +40 Torr neck pressure and -60 Torr neck suction significantly altered mean arterial pressure (MAP) and LVC both at rest and during exercise. CBR-mediated changes in MAP were similar between rest and exercise (P > 0.05). However, CBR-mediated decreases in LVC (%change) to neck pressure were attenuated in the exercising leg (16.4 +/- 1.6%) compared with rest (33 +/- 2.1%) and the nonexercising leg (23.7 +/- 1.9%) (P < 0.01). These data suggest CBR control of blood pressure is partially mediated by changes in leg vascular tone both at rest and during exercise. Furthermore, despite alterations in CBR-induced changes in LVC during exercise, CBR control of blood pressure was well maintained.

Adult↗
PubMed2002

Luteal and follicular glucose fluxes during rest and exercise in 3-h postabsorptive women.

We examined the effects of exercise intensity and menstrual cycle phase on glucose flux rates during rest and exercise in rested and fed (3-h postabsorptive) women. Eight moderately active, eumenorrheic women were studied under conditions of rest (90 min) and exercise (60 min, leg ergometer cycling at 45 and 65% peak oxygen consumption) during follicular and luteal phases. In both menstrual phases, an effect of exercise intensity was evident with glucose rates of appearance and disappearance and metabolic clearance rates: rest < 45% intensity < 65% intensity (P < 0.05). In addition, we observed no significant effect of menstrual phase on glucose rates of appearance and disappearance and metabolic clearance rate during rest or exercise at either intensity. These results are interpreted to mean that in women fed several hours before study 1) glucose flux is directly related to exercise intensity, 2) menstrual cycle phase does not alter glucose flux during rest and exercise, and 3) the subtle effects of endogenous ovarian hormones on glucose kinetics are subordinate to the much larger effects of exercise and recent carbohydrate nutrition.

Adult↗
PubMed2005

Exercise within lower body negative pressure partially counteracts lumbar spine deconditioning associated with 28-day bed rest.

Astronauts experience spine deconditioning during exposure to microgravity due to the lack of axial loads on the spine. Treadmill exercise in a lower body negative pressure (LBNP) chamber provides axial loads on the lumbar spine. We hypothesize that daily supine LBNP exercise helps counteract lumbar spine deconditioning during 28 days of microgravity simulated by bed rest. Twelve sets of healthy, identical twins underwent 6 degrees head-down-tilt bed rest for 28 days. One subject from each set of twins was randomly assigned to the exercise (Ex) group, whereas their sibling served as a nonexercise control (Con). The Ex group exercised in supine posture within a LBNP chamber for 45 min/day, 6 days/wk. All subjects underwent magnetic resonance imaging of their lumbar spine before and at the end of bed rest. Lumbar spinal length increased 3.7 +/- 0.5 mm in the Con group over 28-day bed rest, whereas, in the Ex group, lumbar spinal length increased significantly less (2.3 +/- 0.4 mm, P = 0.01). All lumbar intervertebral disk heights (L5-S1, L4-5, L3-4, L2-3, and L1-2) in the Con group increased significantly over the 28-day bed rest (P < 0.05). In the Ex group, there were no significant increases in L5-S1 and L4-5 disk heights. Lumbar lordosis decreased significantly by 3.3 +/- 1.2 degrees during bed rest in the Con group (P = 0.02), but it did not decrease significantly in the Ex group. Our results suggest that supine LBNP treadmill exercise partially counteracts lumbar spine lengthening and deconditioning associated with simulated microgravity.

Adaptation, Physiological↗
PubMed2006

Effects of changes in central blood volume on carotid-vasomotor baroreflex sensitivity at rest and during exercise.

The purpose of this investigation was to examine whether the effect of changes in central blood volume on carotid-vasomotor baroreflex sensitivity at rest was the same during exercise. Eight men (means +/- SE: age 26 +/- 1 yr; height 180 +/- 3 cm; weight 86 +/- 6 kg) participated in the present study. Sixteen Torr of lower body negative pressure (LBNP) were applied to decrease central venous pressure (CVP) at rest and during steady-state leg cycling at 50% peak O2 uptake (104 +/- 20 W). Subsequently, infusions of 25% human serum albumin solution were administered to increase CVP at rest and during exercise. During all protocols, heart rate, arterial blood pressure, and CVP were recorded continuously. At each stage of LBNP or albumin infusion, the maximal gain (G(max)) of the carotid-vasomotor baroreflex function curve was measured using the neck pressure and neck suction technique. LBNP reduced CVP and increased the G(max) of the carotid-vasomotor baroreflex function curve at rest (+63 +/- 25%, P = 0.006) and during exercise (+69 +/- 19%, P = 0.002). In contrast to the LBNP, increases in CVP resulted in the G(max) of the carotid-vasomotor baroreflex function curve being decreased at rest -8 +/- 4% and during exercise -18 +/- 5% (P > 0.05). These findings indicate that the relationship between CVP and carotid-vasomotor baroreflex sensitivity was nonlinear at rest and during exercise and suggests a saturation load of the cardiopulmonary baroreceptors at which carotid-vasomotor baroreflex sensitivity remains unchanged.

Adult↗
PubMed1993

Residual coronary reserve despite decreased resting blood flow in patients with critical coronary lesions. A study by technetium-99m human albumin microsphere myocardial scintigraphy.

BACKGROUND: Experimental data demonstrate the persistence of a transmural vasodilator reserve in the face of depressed resting myocardial perfusion. The present study was designed to determine whether resting myocardial hypoperfusion indicates exhausted coronary reserve (CR). METHODS AND RESULTS: Fifteen patients with stable angina, isolated left anterior descending coronary artery (LAD) stenosis, and no previous myocardial infarction were evaluated by means of 99mTc human albumin microsphere scintigraphy. Regional myocardial perfusion and CR were assessed at baseline and after LAD papaverine (10-12 mg) by means of two microsphere injections in the left ventricle and compared with five normal subjects. Two 300-second scans were obtained with a mobile gamma camera positioned in the 70 degrees left anterior oblique projection; actual microsphere distribution after papaverine was obtained by image subtraction. The two arterial input functions (basal and papaverine) were measured from the first-pass time-activity curves and validated with the reference arterial sample technique. From the comparison of circumferential profile analysis between patients and normal subjects, nine patients (group 1A) showed perfusion defects at rest (reduction of percent radioactivity below 2 SD of normal subjects) in the LAD territory, and the other six (group 1B) showed homogeneous perfusion. CR (papaverine/resting perfusion) was 3.8 +/- 0.2 and 1.51 +/- 0.27 in normal subjects and in ischemic patients, respectively (p < 0.01). Despite resting hypoperfusion, group 1A showed a papaverine-recruitable CR similar to that of group 1B (1.57 +/- 0.33 and 1.43 +/- 0.16, respectively, p = NS). CONCLUSIONS: In patients with stable angina pectoris, isolated LAD stenosis, and no previous myocardial infarction, microsphere scintigraphy disclosed a high incidence of resting perfusion defects; in those patients, a residual CR was observed despite decreased resting blood flow.

Adult↗
PubMed1985

Thermic effect of food at rest, during exercise, and after exercise in lean and obese men of similar body weight.

The thermic effect of food at rest, during 30 min of cycle ergometer exercise, and after exercise was studied in eight lean (mean +/- SEM, 10 +/- 1% body fat, hydrostatically-determined) and eight obese men (30 +/- 2% body fat). The lean and obese mean were matched with respect to age, height, weight, and body mass index (BMI) to determine the relationship between thermogenesis and body composition, independent of body weight. All men were overweight, defined as a BMI between 26-34, but the obese had three times more body fat and significantly less lean body mass than the lean men. Metabolic rate was measured by indirect calorimetry under four conditions on separate mornings, in randomized order, after an overnight fast: 3 h of rest in the postabsorptive state; 3 h of rest after a 750-kcal mixed meal (14% protein, 31.5% fat, and 54.5% carbohydrate); during 30 min of cycling and for 3 h post exercise in the postabsorptive state; and during 30 min of cycling performed 30 min after the test meal and for 3 h post exercise. The thermic effect of food, which is the difference between postabsorptive and postprandial energy expenditure, was significantly higher for the lean than the obese men under the rest, post exercise, and exercise conditions: the increments in metabolic rate for the lean and obese men, respectively, were 48 +/- 7 vs. 28 +/- 4 kcal over 3 h rest (P less than 0.05); 44 +/- 7 vs. 16 +/- 5 kcal over 3 h post exercise (P less than 0.05); and 19 +/- 3 vs. 6 +/- 3 kcal over 30 min of exercise (P less than 0.05). The thermic effect of food was significantly negatively related to body fat content under the rest (r = -0.55), post exercise (r = -0.66), and exercise (r = -0.58) conditions. The results of this study indicate that for men of similar total body weight and BMI, body composition is a significant determinant of postprandial thermogenesis; the responses of obese are significantly blunted compared with those of lean men.

Adipose Tissue↗
PubMed1991

Relationship between foot transcutaneous oxygen tension and ankle systolic blood pressure at rest and following exercise.

To determine whether foot transcutaneous oxygen tension (TcPO2) and ankle systolic blood pressure (SBP) measure similar aspects of peripheral vascular occlusive disease (PVOD), the authors examined their relationship at rest and following treadmill exercise. Thirty-seven PVOD patients (mean age 69.2 +/- 0.8 years) rested supine for twenty minutes, followed by a progressive treadmill walking test at a constant speed of 2 mph. The initial grade was 0%; this increased 2% every two minutes until maximal claudication pain (n = 19) or until the occurrence of such limiting symptoms as volitional fatigue (n = 6), ST segment depression (n = 4), dyspnea (n = 3), multiple premature ventricular contractions (n = 2), and angina (n = 2). Patients then rested supine for fifteen minutes. Foot TcPO2 was recorded before, during, and after exercise, whereas ankle SBP was measured before and after exercise. At rest, a curvilinear relationship was found between foot TcPO2 and ankle SBP (foot TcPO2 = 41.89 + 0.22(ankle SBP) + 0.0005 (ankle SBP2); SEE = 9.2, R = 0.64, R2 = 0.41, p less than 0.001). In contrast, the relationship was stronger and more linear during recovery, particularly at the sixth minute (foot TcPO2) = 8.33 + 0.35 (ankle SBP); SEE = 13.6, R = 0.86, R2 = 0.73, p less than 0.001). At rest, foot TcPO2 and ankle SBP characterized different aspects of PVOD because they shared only 41% common variance. During recovery, they provided similar information because up to 73% of the variance was shared. It is concluded that foot TcPO2 should also be used to assess PVOD patients because unique information is obtained at rest and values can be recorded during exercise.

Aged↗