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PubMed1997

Is a prolonged bed rest following embryo transfer useful?

A total of 182 infertile patients undergoing in-vitro fertilization (IVF)-embryo transfer were randomly assigned into two groups. Eighty-seven patients (group A) underwent 97 treatment cycles and had 87 embryo transfer procedures followed by a 24 h period of bed rest. Ninety-five patients (group B) underwent 102 treatment cycles and had 93 embryo transfer followed by a 20 min period of bed rest. There were no statistically significant differences seen between the groups with respect to age, duration and causes of infertility and number of previous fertility treatments. The clinical and biological procedures were identical in both groups, the only difference being the length of bed rest. There were 21 pregnancies in group A (pregnancy rate per embryo transfer: 24.1%) while in group B there were 22 (pregnancy rate per embryo transfer: 23.6%). There were four spontaneous miscarriages (19%) and three twin pregnancies (14.2%) in group A, while in group B there were four spontaneous miscarriages (18.1%) and three twin pregnancies (13.6%). None of these values was statistically significant (P > 0.05). This study shows that a 24 h period of bed rest following embryo transfer is not associated with a better outcome of the IVF-embryo transfer when compared with a 20 min rest period. Prolonged bed rest does not appear to influence the implantation rate after IVF-embryo transfer.

Adult↗
PubMed1996

Catecholamines, renin-angiotensin-aldosterone system, and atrial natriuretic peptide at rest and during submaximal exercise in patients with congestive heart failure.

The aim of this study was to determine the responses of plasma catecholamines, renin-angiotensin-aldosterone (RAA) activity, and plasma atrial natriuretic peptide (ANP) to exercise in patients with congestive heart failure (CHF). Cardiac and neurohormonal responses were assessed during submaximal treadmill exercise testing in 23 patients with CHF (New York Heart Association classes I-III) and 13 control subjects (without CHF). Plasma norepinephrine, epinephrine, renin activity (PRA), angiotensin II (ATII), aldosterone, and ANP were measured at rest and immediately after exercise. Exercise duration was shorter in patients with CHF (control, 10.4 +/- 0.9 minute; CHF, 6.2 +/- 0.7 minute; P < 0.01). Heart rate and blood pressure responses were similar except for the smaller peak heart rate (control, 145 +/- 5 beats per minute; CHF, 129 +/- 4 beats per minute; P < 0.05) and higher systolic blood pressure at recovery stage (control, 122 +/- 4 mm Hg; CHF, 142 +/- 4 mm Hg; P < 0.01) in patients with CHF. At rest, plasma norepinephrine levels were insignificantly higher in patients with CHF (control, 110 +/- 10 pg/mL; CHF, 170 +/- 26 pg/mL; P = 0.09), and ANP levels (control, 40 +/- 5 pg/mL; CHF, 94 +/- 17 pg/mL; P < 0.05) and PRA levels (control, 0.77 +/- 0.11 ng/mL/hr; CHF, 4.33 +/- 1.25 ng/mL/hr; P < 0.05) were significantly higher. There were no differences in peak norepinephrine, epinephrine, or ANP between the two groups. Angiotensin II and aldosterone levels were similar between the two groups, although, in patients with CHF, there was a trend toward higher levels of ATII while at rest (control, 12.4 +/- 1.4 pg/mL; CHF, 20.3 +/- 3.3 pg/mL; P = 0.08) and at peak (control, 20.5 +/- 1.8 pg/mL; CHF, 41.0 +/- 9.4 pg/mL; P = 0.10). Peak values of PRA, ATII, and aldosterone positively correlated with respective resting values of PRA (r = 0.88 ng/mL/hr, P < 0.01), ATII (r = 0.63 pg/mL, P < 0.01), and aldosterone (r = 0.99, P < 0.01). Peak norepinephrine and peak ANP also positively correlated with respective resting values of norepinephrine (r = 0.58 pg/mL, P < 0.05) and ANP (r = 0.94, P < 0.01). Analysis of these results showed that patients with CHF had significantly higher levels of PRA and ANP at rest, and a trend toward augmentation in RAA system activity during exercise with less exercise workload. Basal level of neurohormones seemed to be an important determinant for the degree of exercise-induced neurohormonal activation in patients with CHF.

Atrial Natriuretic Factor↗
PubMed1997

An overview of the issues: physiological effects of bed rest and restricted physical activity.

Reduction of exercise capacity with confinement to bed rest is well recognized. Underlying physiological mechanisms include dramatic reductions in maximal stroke volume, cardiac output, and oxygen uptake. However, bed rest by itself does not appear to contribute to cardiac dysfunction. Increased muscle fatigue is associated with reduced muscle blood flow, red cell volume, capillarization and oxidative enzymes. Loss of muscle mass and bone density may be reflected by reduced muscle strength and higher risk for injury to bones and joints. The resultant deconditioning caused by bed rest can be independent of the primary disease and physically debilitating in patients who attempt to reambulate to normal active living and working. A challenge to clinicians and health care specialists has been the identification of appropriate and effective methods to restore physical capacity of patients during or after restricted physical activity associated with prolonged bed rest. The examination of physiological responses to bed rest deconditioning and exercise training in healthy subjects has provided significant information to develop effective rehabilitation treatments. The successful application of acute exercise to enhance orthostatic stability, daily endurance exercise to maintain aerobic capacity, or specific resistance exercises to maintain musculoskeletal integrity rather than the use of surgical, pharmacological, and other medical treatments for clinical conditions has been enhanced by investigation and understanding of underlying mechanisms that distinguish physical deconditioning from the disease. This symposium presents an overview of cardiovascular and musculoskeletal deconditioning associated with reduced physical work capacity following prolonged bed rest and exercise training regimens that have proven successful in ameliorating or reversing these adverse effects.

Bed Rest↗
PubMed1997

Changes in musculoskeletal structure and function with prolonged bed rest.

Prolonged bed rest produces profound changes in muscle and bone, particularly of the lower limb. This review first addresses the various models used by researchers to study disuse-induced changes in muscle and bone as observed during prolonged bed rest in humans. Dramatic change in muscle mass occurs within 4-6 wk of bed rest, accompanied by decreases of 6 to 40% in muscle strength. Immobilization studies in humans suggest that most of this lost muscle mass and strength can be regained with appropriate resistance training within several weeks after a period of disuse. Significant decrements in bone mineral density of the lumbar spine, femoral neck, and calcaneus observed in able-bodied men after bed rest are not fully reversed after 6 months of normal weightbearing activity. Importantly, the lost bone mass is not regained for some weeks or months after muscle mass and strength have returned to normal, further contributing to the risk of fracture. Those who enter a period of bed rest with subnormal muscle and bone mass, especially the elderly, are likely to incur additional risk of injury upon reambulation. Practical implications for exercise professionals working with individuals confined to bed rest are discussed.

Animals↗
PubMed1997

Upright exercise or supine lower body negative pressure exercise maintains exercise responses after bed rest.

Adaptation to bed rest or space flight is accompanied by an impaired ability to exercise in an upright position. We hypothesized that a daily, 30-min bout of intense, interval exercise in upright posture or supine against lower body negative pressure (LBNP) would maintain upright exercise heart rate and respiratory responses after bed rest. Twenty-four men (31 +/- 3 yr) underwent 5 d of 6 degree head-down tilt: eight performed no exercise (CON), eight performed upright treadmill exercise (UPex), and eight performed supine treadmill exercise against LBNP at -51.3 +/- 0.4 mm Hg (LBNPex). Submaximal treadmill exercise responses (56, 74, and 85% of VO2peak) were measured pre- and post-bed rest. In CON, submaximal heart rate, respiratory exchange ratio, and ventilation were significantly greater (P < or = 0.05) after bed rest. In UPex and LBNPex, submaximal exercise responses were similar pre- and post-bed rest. Our results indicate that a daily 30-min bout of intense, interval upright exercise training or supine exercise training against LBNP is sufficient to maintain upright exercise responses after 5 d of bed rest. These results may have important implications for the development of exercise countermeasures during space flight.

Adult↗
PubMed2004

Reproducibility of regional left ventricular wall thickening obtained by gating resting and redistribution 201Tl myocardial SPECT studies.

BACKGROUND: We have assessed the reproducibility of the estimates of regional left ventricular wall thickening between resting and redistribution Tl gated single photon emission computed tomography (SPECT) studies. METHODS: Thirty patients (28 males, two females) aged between 38 and 72 years (57.0 +/- 8.4 years) underwent resting and redistribution Tl gated SPECT. Perfusion was assessed semi-quantitatively using scores of 0-4. The assessment of wall thickening was performed both visually and by using automated software using scores of 0-3. The assessment of reproducibility was performed in 20 individual segments and 37 pairs of contiguous segments in each patient. RESULTS: In resting studies, mean global left ventricular ejection fraction (LVEF), end diastolic volume and end systolic volume were 34.2 +/- 11.7%, 180.5 +/- 70.6 ml and 123.3 +/- 60.0 ml, respectively. The corresponding values for the redistribution studies were 32.7 +/- 10.1%, 179.7 +/- 70.6 ml and 125.5 + 63.0 ml, respectively. There was good correlation between the resting and redistribution LVEFs (r=0.88), end diastolic volumes (r=0.90) and end systolic volumes (r=0.933). Reproducibility of visual wall thickening was 66% in individual segments and 82% in pairs of contiguous segments, and that of automated wall thickening was 48.0% in individual segments and 68% in pairs of contiguous segments. CONCLUSION: In conclusion, global left ventricular functional parameters obtained by resting Tl gated SPECT studies are highly reproducible in patients with impaired resting left ventricular function and large areas of scarred myocardium. Wall thickening and wall motion data are more reproducible in contiguous segments than in individual segments.

Adult↗
PubMed2006

Left ventricular ejection fraction and volumes on rest gated 201Tl perfusion SPECT: comparison with two-dimensional echocardiography.

BACKGROUND: Rest gated 201Tl images are considered to be of poor count statistics due to lower energy and low photon flux of 201Tl in addition to increased attenuation and low dose that can be administered. We compared the left ventricular ejection fraction (LVEF), end diastolic (EDV) and end systolic volume (ESV) obtained on 4 h gated rest 201Tl myocardial perfusion single photon emission computed tomography (SPECT) with those obtained by two-dimensional echocardiography (2-D ECHO) in patients with known or suspected coronary artery disease (CAD). METHODS: Eighty-two consecutive patients who underwent gated 201Tl stress-rest myocardial perfusion SPECT and 2-D ECHO were studied. The gated thallium images were processed with Siemens e-soft autocardiac processor and LVEF, EDV and ESV were evaluated using Emory Cardiac Toolbox. The same parameters were also assessed on the 2-D ECHO using the modified Simpson method for comparison. RESULTS: Out of 82 rest gated images, one study was excluded because of poor count statistics. In 81 (99%) patients there was good linear correlation with 2-D ECHO values and rest gated 201Tl SPECT images for EDV, ESV and LVEF. Pearson's correlation co-efficient (r value) for EDV, ESV and LVEF between the two methods was 0.78, 0.79 and 0.88, respectively. A Bland-Altman plot showed close agreement with LVEF but not for EDV and ESV. CONCLUSION: These results suggest that the 4 h rest gated 201Tl study gives a reliable value for the LVEF compared to 2-D ECHO and can be used in routine clinical practice.

Adult↗
PubMed2002

Bed rest or normal activity for patients with acute low back pain: a randomized controlled trial.

BACKGROUND: The management of common low back pain has two principal objectives: to relieve acute pain and to attempt prevention of transition to chronicity. Several studies have shown the ineffectiveness of prolonged periods of bed rest. OBJECTIVE: To compare 4 days of bed rest with continued normal daily activity in acute low back pain, taking into account the type of work (physical or sedentary labor). METHODS: This open, comparative multicenter study enrolled 281 ambulatory patients, ages 18 to 65 years, with low back pain (onset < 72 hours). The subjects did not have pain radiating below the buttocks and did not have work-related injuries. They were randomized into two treatment groups: one instructed to continue normal activity (insofar as the pain allowed), and the other prescribed 4 days of bed rest. After inclusion, patients were seen at three visits: on day 6 or 7, after 1 month, and after 3 months. RESULTS: On day 6 or 7, pain intensity was similar for both groups, as was the overall judgment of the treatment by patients and physicians. At 1 and 3 months, the groups again had equivalent intensity of back pain, functional disability, and vertebral stiffness. A higher proportion of patients in the bed rest group than in the normal activity group had an initial sick leave (86% vs 52%; P < 0.0001). This difference was greater for the patients whose work was sedentary. CONCLUSIONS: For patients with acute low back pain, normal activity is at least equivalent to bed rest. The findings of this study indicate that prescriptions for bed rest, and thus for sick leaves, should be limited when the physical demands of the job are similar to those for daily life activities.

Activities of Daily Living↗
PubMed2005

Comparison of fingertip to arterial blood samples at rest and during exercise.

OBJECTIVE: The purpose was to determine whether arterialized fingertip blood-gas samples are comparable to arterial samples at rest and at exercise. DESIGN: Repeated measures, with subjects serving as their own controls. SETTING: Department of Anesthesia, Montreal General Hospital, Montreal, Quebec, Canada, (January to April 2004). PARTICIPANTS: Fifteen healthy men (age = 25 +/- 4 y; weight = 76.4 +/- 11.4 kg; height = 180.7 +/- 8.0 cm; peak oxygen uptake or VO2peak = 46.0 +/- 9.0 mL . kg . min). MAIN OUTCOME MEASURES: Arterial blood gases, metabolites, electrolytes. RESULTS: Blood sampled simultaneously from the radial artery and warmed fingertip at rest and during 2 levels of exercise (vigorous 181 W or 70% VO2peak; maximal 261 W or 100% VO2peak) on a electronically braked ergometer. Arterial partial pressure of oxygen in blood combining rest and the 2 exercise levels was on average 13.6 +/- 9.0 mm Hg higher than arterialized fingertip samples, with the largest difference occurring at rest (18.8 +/- 6.5 mm Hg; 95% CI = 15.5, 22.1) and the smallest difference occurring at the highest level of exercise (8.3 +/- 9.2 mm Hg; 95% CI = 3.6, 13.0; P < 0.05). The pattern for oxyhemoglobin saturation was the same, showing statistical differences between the sampling sites with the differences reduced at the highest exercise intensity. In contrast, there was no difference in arterial and arterialized partial pressure of carbon dioxide in blood (-1.0 +/- 1.5 mm Hg; 95% CI = -1.4, -0.6), or plasma lactate, glucose, pH, hemoglobin, and electrolytes between both sampling sites at rest or at the 2 exercise levels. CONCLUSION: Arterialized fingertip blood samples at rest and during exercise can predict arterial carbon dioxide pressure, and can predict arterial plasma lactate, glucose, pH, hemoglobin, and electrolytes; but not arterial oxyhemoglobin saturation or arterial oxygen pressure.

Adult↗
PubMed1998

Rest and exercise hemodynamics after the Ross procedure: an echocardiographic study.

BACKGROUND: Aortic prosthetic valves with superior hemodynamic performance are associated with more complete regression of left ventricular hypertrophy and better left ventricular function postoperatively. The near normal function of the pulmonary autografts at rest is well documented, however, exercise data has been seldom reported. The purpose of this study is to evaluate the hemodynamic performance of pulmonary autografts in the aortic position and the homografts used to reconstruct the right ventricular outflow tract during conditions of high cardiac output by means of dobutamine stress echocardiography. METHODS: Between May 1995 and February 1998, 67 patients were submitted to a Ross operation at our institution. Twenty of these patients had a mean age of 28.6+/-8.3 years and a mean follow-up time of 15.7+/-5.9 months. They were studied by dobutamine stress echocardiography to evaluate rest and exercise hemodynamics of the pulmonary autografts as well as of the aortic and pulmonary homografts used to reconstruct the right ventricular outflow tract. Dobutamine infusion was started at 5 microg/kg with incremental doses up to 40 microg/kg in every case. RESULTS: With dobutamine infusion, heart rate increased from 71+/-10 to 142+/-11 beats/min, left ventricular systolic volume from 86.8+/-33.9 mL to 115.9+/-52.6 mL, and cardiac output from 6.3+/-2.9 L/min to 16.8+/-7.4 L/min. Left ventricular function was considered satisfactory at rest and during exercise in all patients. The mean gradient across the autograft increased from 1.03+/-0.95 mmHg to 4.03+/-2.05 mmHg and maximal instantaneous gradient from 2.45+/-2.21 mmHg to 9.54+/-4.85 mmHg. The mean effective orifice area for the autografts were 3.5+/-1.3 cm2 at rest and 3.3+/-1.4 cm2 during exercise. The patients with mild aortic insufficiency at rest had no increase in the degree of regurgitation with exercise. In the right ventricular outflow tract, the mean gradient across the homograft increased from 9.06+/-5.29 mmHg to 17.55+/-9.76 mmHg and maximal instantaneous gradient from 21.4+/-12.5 mmHg to 41.5+/-23.1 mmHg. CONCLUSIONS: Pulmonary autografts exhibit normal hemodynamic performance at rest and during exercise after the Ross operation. However, mild-to-moderate gradients are common at the right ventricular outflow tract and should be carefully monitored.

Adolescent↗
PubMed2003

Relative rates of anaplerotic flux in rested and contracted rat skeletal muscle measured by 13C NMR spectroscopy.

Flux through anaplerotic pathways in skeletal muscle has not been evaluated quantitatively during both rest and contraction, nor have fibre type-specific rates of anaplerotic flux been studied. Steady-state analysis using 13C NMR spectroscopy enables calculation of Y (flux rate through anaplerotic pathways relative to tricarboxylic acid (TCA) cycle flux). Under inhalation anaesthesia, [2,4,6,8-13C4]octanoate was infused into the jugular vein of the intact rat (n = 10) and the sciatic nerve of one limb was stimulated at the voltage required to elicit maximal force output at 0.5 Hz. In resting muscle, Y was higher in soleus (0.41 +/- 0.22) versus white gastrocnemius (WG) (0.18 +/- 0.11). Y was 0.29 +/- 0.06 in the predominantly red portion of the gastrocnemius (RG) during rest. During contraction, Y was similar to the resting value in soleus (0.34 +/- 0.14), RG (0.20 +/- 0.04) and WG (0.15 +/- 0.08); Y was higher in soleus versus both RG and WG during contraction. These results demonstrate: (1) relative flux through anaplerotic pathways is 15-41 % of TCA cycle flux at rest and during muscle contraction, (2) higher relative anaplerotic flux in oxidative (soleus) versus glycolytic muscle (WG) during rest and in slow-twitch (soleus) versus fast-twitch (RG and WG) muscle during contraction, and (3) relative flux through anaplerotic pathways is maintained in all muscle fibre types during contraction, which indicates that absolute rates of anaplerotic flux rise in proportion to increased oxidation rates during contraction. These results are consistent with a sustained increase in substrate entry into and exit from the TCA cycle through anaplerotic pathways during contraction.

Animals↗
PubMed2004

Human single muscle fibre function with 84 day bed-rest and resistance exercise.

Muscle biopsies were obtained from the vastus lateralis before and after 84 days of bed-rest from six control (BR) and six resistance-exercised (BRE) men to examine slow- and fast-twitch muscle fibre contractile function. BR did not exercise during bed-rest and had a 17 and 40% decrease in whole muscle size and function, respectively. The BRE group performed four sets of seven maximal concentric and eccentric supine squats 2-3 days per week (every third day) that maintained whole muscle strength and size. Slow (MHC I) and fast (MHC IIa) muscle fibres were studied at 15 degrees C for diameter, peak force (P(o)), contractile velocity (V(o)) and force-power parameters. SDS-PAGE was performed on each single fibre after the functional experiments to determine MHC isoform composition. MHC I and IIa BR fibres were, respectively, 15 and 8% smaller, 46 and 25% weaker (P(o)), 21 and 6% slower (V(o)), and 54 and 24% less powerful after bed-rest (P < 0.05). BR MHC I and IIa P(o) and power normalized to cell size were lower (P < 0.05). BRE MHC I fibres showed no change in size or V(o) after bed-rest; however, P(o) was 19% lower (P < 0.05), resulting in 20 and 30% declines (P < 0.05) in normalized P(o) and power, respectively. BRE MHC IIa fibres showed no change in size, P(o) and power after bed-rest, while V(o) was elevated 13% (P < 0.05). BRE MHC IIa normalized P(o) and power were 10 and 15% lower (P < 0.05), respectively. MHC isoform composition shifted away from MHC I fibres, resulting in an increase (P < 0.05) in MHC I/IIa (BR and BRE) and MHC IIa/IIx (BR only) fibres. These data show that the contractile function of the MHC I fibres was more affected by bed-rest and less influenced by the resistance exercise protocol than the MHC IIa fibres. Considering the large differences in power of human MHC I and IIa muscle fibres (5- to 6-fold), the maintenance of whole muscle function with the resistance exercise programme is probably explained by (1). the maintenance of MHC IIa power and (2). the shift from slow to fast (MHC I --> MHC I/IIa) in single fibre MHC isoform composition.

Adult↗
PubMed2004

Short-term bed rest impairs amino acid-induced protein anabolism in humans.

Diminished muscular activity is associated with alterations of protein metabolism. The aim of this study was to evaluate the effect of short-term muscle inactivity on regulation of whole-body protein deposition during amino acid infusion to simulate an experimental postprandial state. We studied nine healthy young volunteers at the end of 14 day periods of strict bed rest and of controlled ambulation using a cross-over design. Subjects received a weight-maintaining diet containing 1 g protein kg(-1) day(-1). l[1-(13)C]leucine was used as a marker of whole-body protein kinetics in the postabsorptive state and during a 3 h infusion of an amino acid mixture (0.13 g amino acid (kg lean body mass)(-1) h(-1)). In the postabsorptive state, bed rest decreased (P < 0.05) the rate of leucine disposal (R(d)) to protein synthesis and tended to decrease leucine rate of appearance (R(a)) from proteolysis, whereas the rate of leucine oxidation did not change significantly. Amino acid infusion increased leucine R(d) to protein synthesis and oxidation and decreased leucine R(a) from proteolysis in both the bed rest and ambulatory conditions. Changes from basal in leucine R(d) to protein synthesis were lower (P < 0.05) during bed rest than those in the ambulatory period, whereas changes in leucine R(a) from proteolysis and oxidation were not significantly different. During amino acid infusion, net leucine deposition into body protein was 8 +/- 3% lower during bed rest than during the ambulatory phase. In conclusion, short-term bed rest leads to reduced stimulation of whole-body protein synthesis by amino acid administration. Results of this study were, in part, presented at the meeting, Experimental Biology, 2004, Washington DC.

Adult↗
PubMed2005

The effect of changes in cardiac output on middle cerebral artery mean blood velocity at rest and during exercise.

We examined the relationship between changes in cardiac output and middle cerebral artery mean blood velocity (MCA V(mean)) in seven healthy volunteer men at rest and during 50% maximal oxygen uptake steady-state submaximal cycling exercise. Reductions in were accomplished using lower body negative pressure (LBNP), while increases in were accomplished using infusions of 25% human serum albumin. Heart rate (HR), arterial blood pressure and MCA V(mean) were continuously recorded. At each stage of LBNP and albumin infusion was measured using an acetylene rebreathing technique. Arterial blood samples were analysed for partial pressure of carbon dioxide tension (P(a,CO2). During exercise HR and were increased above rest (P < 0.001), while neither MCA V(mean) nor P(a,CO2) was altered (P > 0.05). The MCA V(mean) and were linearly related at rest (P < 0.001) and during exercise (P = 0.035). The slope of the regression relationship between MCA V(mean) and at rest was greater (P = 0.035) than during exercise. In addition, the phase and gain between MCA V(mean) and mean arterial pressure in the low frequency range were not altered from rest to exercise indicating that the cerebral autoregulation was maintained. These data suggest that the associated with the changes in central blood volume influence the MCA V(mean) at rest and during exercise and its regulation is independent of cerebral autoregulation. It appears that the exercise induced sympathoexcitation and the change in the distribution of between the cerebral and the systemic circulation modifies the relationship between MCA V(mean) and .

Adult↗
PubMed2000

Effect of acute resistance exercise on postexercise oxygen consumption and resting metabolic rate in young women.

This study determined the effect of an intense bout of resistive exercise on postexercise oxygen consumption, resting metabolic rate, and resting fat oxidation in young women (N=7, ages 22-35). On the morning of Day 1, resting metabolic rate (RMR) was measured by indirect calorimetry. At 13:00 hr, preexercise resting oxygen consumption was measured followed by 100 min of resistive exercise. Postexercise oxygen consumption was then measured for a 3-hr recovery period. On the following morning (Day 2), RMR was once again measured in a fasted state at 07:00. Postexercise oxygen consumption remained elevated during the entire 3-hr postexercise recovery period compared to the pre-exercise baseline. Resting metabolic rate was increased by 4.2% (p<.05) from Day 1 (morning prior to exercise: 1,419 +/- 58 kcal/24hr) compared to Day 2 (16 hr following exercise: 1,479 +/- kcal/24hr). Resting fat oxidation as determined by the respiratory exchange ratio was also significantly elevated on Day 2 compared to Day 1. These results indicate that among young women, acute strenuous resistance exercise of the nature used in this study is capable of producing modest but prolonged elevations of postexercise metabolic rate and possibly fat oxidation.

Adult↗
PubMed2006

Glucocorticoid resorption and influence on the hypothalamic-pituitary-adrenal axis after intra-articular treatment of the knee in resting and mobile patients.

BACKGROUND: Studies have shown that intra-articular glucocorticoid injection treatment for knee synovitis has a better outcome in resting patients than in mobile patients. One reason for this observation might be that rest retards steroid resorption, causing an enhanced local treatment effect. OBJECTIVES: To study drug resorption and the impact on hormone production in the hypothalamic-pituitary-adrenal axis after intra-articular glucocorticoid administration, with and without postinjection rest. METHODS: Twenty patients with rheumatoid arthritis and knee synovitis were randomised to either 24 hour bed rest or normal activity after intra-articular glucocorticoid treatment with 20 mg triamcinolone hexacetonide (THA). Serum levels of THA, cortisol, and adrenocorticotropic hormone (ACTH) were followed during 2 weeks. RESULTS: Short term and reversible decreases in serum cortisol and ACTH levels (p<0.001) were seen, without any significant differences between resting and mobile patients. The THA levels increased similarly in both groups, with the median serum peak seen after 8 hours. CONCLUSION: Immobilisation does not appear to retard glucocorticoid resorption after intra-articular administration. Further studies are therefore needed to clarify the mechanism behind the beneficial effects of rest after intra-articular glucocorticoid treatment for knee synovitis.

Absorption↗
PubMed1988

Cardiovascular function at rest and on exercise in patients with cryptogenic fibrosing alveolitis.

Cardiovascular complications are common in fibrosing alveolitis, but there have been few physiological studies of the pulmonary circulation in this condition, and those that have been carried out have usually depended on right heart catheterisation. This paper reports non-invasive measurements of effective pulmonary blood flow, oxygen uptake, pulmonary arteriovenous oxygen content differences, and estimates of mixed venous oxygen saturation in 20 patients with histologically proved cryptogenic fibrosing alveolitis at rest and while exercising on a motorized treadmill. Results were compared with those of 20 age and sex matched normal subjects, at rest and at an arbitrarily chosen oxygen uptake of 0.75 l/min. The latter results were obtained by linear interpolation. Effective pulmonary blood flow was normal at rest, but oxygen dispatch to the tissues (blood flow x blood oxygen content) was significantly reduced at rest (mean reduction 190 (SD 68) ml/l/min; p less than 0.01) and at an oxygen uptake of 0.75 l/min (mean reduction 128 (50) ml/l/min; p less than 0.02), reflecting the presence of systemic arterial hypoxaemia. Pulmonary arteriovenous oxygen content differences were similar in patients and normal subjects, but mixed venous saturation was lower in the patients at rest (mean % reduction 6.8 (2.6); p less than 0.02) and at an oxygen uptake of 0.75 l/min (mean % reduction 9.6 (2.9); p less than 0.002). It is concluded that the supply of oxygen potentially available to the tissues is reduced at rest and during exercise in patients with fibrosing alveolitis and hence, by analogy with normal people exercising under hypoxic conditions, that pulmonary blood flow is inappropriately low in this condition. The low mixed venous oxygen saturation may contribute to the development of pulmonary hypertension in some patients. The rebreathing technique used in this study may be of use in monitoring treatment; it could be applied many times to the same patient, and might be a suitable way of following the response to pulmonary vasodilators.

Adult↗
PubMed1992

Relationship between intracellular pH and tension development in resting ventricular muscle and myocytes.

Simultaneous measurements of intracellular pH (pHi) and tension development were made in resting cat papillary muscles and resting ventricular myocytes (cat, guinea pig). pH microelectrodes and the fluorescent indicator carboxy-seminaphthorhodafluor-1 (SNARF-1) were used to measure pHi in muscles and myocytes, respectively. pHi-induced changes in isometric muscle tension and myocyte length were elicited by variations in PCO2, HCO3-, and [NH4Cl]. Increased pHi elevated resting tension and decreased resting cell length, whereas decreased pHi decreased tension and increased cell length. The tension-pHi and cell length-pHi relationships were nonlinear and displayed hysteresis. A reduction in extracellular [Ca2+] from 2.7 to 0.5 mM caused little or no change in the tension and cell length responses to elevated pHi. Ca2+ uptake and/or release by the sarcoplasmic reticulum (SR) does not appear to be involved in the tension response to intracellular alkalosis because the response was unaffected by a postpacing rest period and was not inhibited by ryanodine (5 microM), which depletes SR Ca2+ stores. The cross-bridge inhibitor 2,3-butanedione monoxime (15 mM), but not internal dialysis with 14 mM ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid, inhibited myocyte contractures elicited by elevated pHi. The latter finding suggests that factors other than pHi-induced increase in myofilament Ca2+ sensitivity may contribute to the resting contractile response to elevated pHi.

Animals↗