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At least 721 records · Page 40Linked to original sources
PubMed1997

Qualitative aspects of exertional breathlessness in chronic airflow limitation: pathophysiologic mechanisms.

We compared qualitative aspects of the sensory experience of exertional breathlessness in normal subjects and in patients with chronic airflow limitation (CAL) and sought a physiologic rationale for these. Twelve patients (66 +/- 2 yr of age, mean +/- SEM) with severe CAL (FEV1 = 37 +/- 5% predicted) and 12 age-matched normal subjects (FEV1 = 103 +/- 5% predicted) were studied. Perceived inspiratory difficulty (BorgIN), inspiratory effort (esophageal pressure expressed as a fraction of maximal esophageal pressure at isovolume [Pes/PImax]), breathing pattern, and operational lung volumes (end-expiratory/inspiratory lung volumes [EELV/EILV]) were measured during symptom-limited incremental cycle exercise testing and compared at a standard VO2 of 50% predicted maximum in normal subjects and in patients with CAL. Qualitative descriptors of breathlessness were selected immediately after exercise. Breathlessness was qualitatively different between normal subjects and patients with CAL. Both normal subjects and patients with CAL chose descriptors of increased "work/effort" and "heaviness" of breathing; however, only patients with CAL consistently chose descriptors denoting "increased inspiratory difficulty" (75%), "unsatisfied inspiratory effort" (75%), and "shallow breathing" (50%). Stepwise regression analysis identified the ratio of Pes/PImax to VT/predicted VC as the strongest correlate of standardized BorgIN (n = 24, r = 0.86, p < 0.001). This latter measurement, which reflects the relationship between effort and ventilatory output, correlated strongly with dynamic EELV/TLC at isotime (r = 0.78, p < 0.001). In conclusion, the qualitatively discrete respiratory sensations of exertional inspiratory difficulty peculiar to patients with CAL may have their origins in thoracic hyperinflation and the resultant disparity between inspiratory effort and ventilatory output.

Aged↗
PubMed1997

Factors contributing to relief of exertional breathlessness during hyperoxia in chronic airflow limitation.

The mechanisms of exertional dyspnea relief in response to supplemental oxygen (O2) in chronic airflow limitation (CAL) are not precisely known and are likely multifactorial. To explore factors contributing to the relief of dyspnea after oxygen administration, 11 patients with severe CAL (FEV1.0 = 39 +/- 3% predicted, mean +/- SEM) and mild hypoxemia (resting PaO2 = 74 +/- 2 mm Hg) breathed room air (RA) and 60% O2 during exercise at approximately 50% of their maximal incremental exercise capacity. Breathlessness ratings (Borg scale), endurance time, respiratory drive (change in mouth occlusion pressure over the first 0.1 s of inspiration, P0.1), ventilation (VE), breathing pattern, operational lung volumes, gas exchange, and metabolic parameters were compared during RA and 60% O2. PaO2 at exercise cessation during RA and 60% O2 was 65 +/- 3 mm Hg and 226 +/- 12 mm Hg, respectively (p < 0.001). With 60% O2, the mean of individual Borg/time slopes fell significantly (p < 0.05) by 23 +/- 12% and was associated with a 35 +/- 11% increase (p < 0.01) in endurance time (r = -0.64, p < 0.05). During 60% O2, slopes of P0.1 and lactate over time also fell significantly (p < 0.05), whereas delta PaCO2/time did not change significantly. At a standardized time near end-exercise, Borg, VE, and P0.1 changed during 60% O2 by -0.8 +/- 0.3 (p < 0.05), -4.1 +/- 2.0 L/min (p = 0.07), and -1.3 +/- 0.5 cm H2O/s (p < 0.05), respectively. Slopes of Borg/VE, Borg/lactate, and VE/lactate were essentially superimposable during tests on RA and O2: Borg, lactate, and VE all fell proportionally during hyperoxia. In patients with CAL and mild exercise hypoxemia, relief of exertional breathlessness during hyperoxia is explained by reduced ventilatory demand in association with reduced blood lactate levels.

Aged↗
PubMed1995

Intravenously injected insulin-like growth factor (IGF) I/IGF binding protein-3 complex exerts insulin-like effects in hypophysectomized, but not in normal rats.

Insulin-like growth factor (IGF) circulates in blood in two large molecular mass forms of 150 and 40 kD. Under normal conditions, most of the IGF is bound to the 150-kD complex by which it is retained in the circulation and therefore unable to exert acute insulin-like actions. The aim of this study was to answer the question whether or not IGF in the 40-kD complex is bioavailable to insulin target tissues and thus can cause acute insulin-like effects in vivo. Intravenously injected 1:1 molar recombinant human (rh) IGF I/rhIGF binding protein (BP)-3 complex lowered blood glucose and stimulated glycogen synthesis in diaphragm of hypophysectomized, but not of normal rats. The serum half-lives of the two components of the complex were similar to each other, but considerably shorter in hypox than in normal rats. On neutral gel filtration of serum both components of the injected complex appeared predominantly in the 150-kD region in normal rats. In hypox rats which lack the 150-kD complex they were found in the 40-kD region and disappeared rapidly from the circulation. We conclude that in the absence of the 150-kD complex, IGF associated with the 40-kD complex can rapidly leave the vascular compartment, reach insulin or type 1 IGF receptors and exert acute insulin-like effects.

Animals↗
PubMed2005

Revision surgery for exertional anterior compartment syndrome of the lower leg: technique, findings, and results.

BACKGROUND: Recurrent symptoms or failure after fasciotomy for exertional anterior compartment syndrome is not uncommon. HYPOTHESIS: Symptoms from high compartment pressures can be secondary to involvement of the entire compartment or to localized constrictions from postsurgical fibrosis, as well as to entrapment of the superficial peroneal nerve. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Eighteen patients who underwent revision surgery for exertional anterior compartment syndrome were available for follow-up. All were athletes who had either a failure or a recurrence of symptoms at a mean of 23.5 months (range, 8-54 months) after the index fasciotomy. Pressure measurements using a slit catheter at rest, at 1 minute postexercise, and at 5 minutes postexercise were performed in 2 places within the compartment: in the area of the previous incision and in the proximal muscle belly of the tibialis anterior. Surgical technique consisted of a 2-incision approach with partial fasciectomy, exploration and decompression of the superficial peroneal nerve, and excision of all fibrotic tissue. An objective examination and a comprehensive subjective questionnaire previously described were performed at a mean follow-up of 42 months (range, 22-67 months). RESULTS: Sixty percent of patients had abnormal pressures only in a localized area, whereas 40% had high pressures throughout the compartment. Eight of 18 (44%) patients had symptoms, signs, and surgical findings of entrapment of the superficial peroneal nerve. At follow-up, 72% of patients had a satisfactory outcome (5 excellent, 8 good), and 28% had an unsatisfactory outcome for intense running sports (4 fair, 1 poor), although 3 patients with the fair results reported improvement with low-level activity. All 8 patients with documented peroneal nerve entrapment had a satisfactory outcome. CONCLUSION: Symptoms from high pressures can be secondary to involvement of the entire compartment or localized to a certain area from postsurgical fibrosis. Pressure measurements should be performed in at least 2 separate areas.

Compartment Syndromes↗
PubMed2005

Bilateral simultaneous fasciotomy for chronic exertional compartment syndrome.

BACKGROUND: Chronic exertional compartment syndrome (CECS) occurs bilaterally in approximately 60% of patients. Fasciotomy is the primary corrective treatment. We hypothesized that bilateral fasciotomy can be done during the same operative procedure with early return to sports and low complication rates METHOD: Sixteen patients had simultaneous bilateral lower extremity fasciotomies for CECS confirmed by compartment pressure testing before and after exercise. Ten patients had concomitant superficial peroneal neurolysis for associated numbness. All patients who were athletes (six runners; nine ball sports) (average age 25 years) had sports related pain limiting participation. RESULTS: Patients were followed for an average of 16.4 (range 6 to 48) months. Full return to sports participation occurred at an average of 10.7 weeks. Three patients continued to have mild, but much improved, pain with active sports participation, while 13 were pain free. All 11 patients with exertional related numbness had resolution after operative release. All patients were satisfied and all patients stated that they would have simultaneous fasciotomies again if required. As a nonmatched comparison, three patients who had staged fasciotomies for bilateral CECS were also evaluated, but because of the small number no statistical comparison was made. All three also returned to their previous levels of sports participation, however, at an average of 22.7 months as compared to 10.7 weeks in patients with simultaneous bilateral releases. CONCLUSION: Bilateral simultaneous fasciotomies for CECS can be done safely and effectively with early return to sports participation and low complication rates.

Adolescent↗
PubMed2003

Evidence that growth hormone exerts a feedback effect on stomach ghrelin production and secretion.

Ghrelin is a recently discovered stomach hormone that stimulates pituitary growth hormone (GH) secretion potently. The purpose of these experiments was to test the hypothesis that a stomach-ghrelin-pituitary-GH axis exists in which either an elevation or reduction in systemic GH levels will exert a negative or positive feedback action, respectively, on stomach ghrelin homeostasis. In rats, GH administration decreased stomach ghrelin mRNA levels and plasma ghrelin levels significantly. In GH-releasing hormone (GHRH) transgenic mice, GHRH overexpression decreased stomach ghrelin peptide levels when compared with control mice. In aged rats (25 months) stomach ghrelin mRNA and peptide levels and plasma ghrelin levels were decreased when compared with young rats (5 months). Because GH secretion is reduced in aged rats, the elevated stomach ghrelin production and secretion may reflect a decreased GH feedback on stomach ghrelin, homeostasis, and secretion. Together, these findings suggest that endogenous pituitary GH exerts a feedback action on stomach ghrelin homeostasis and support the hypothesis that a stomach-ghrelin-pituitary GH axis exists.

Age Factors↗
PubMed1988

Forces exerted by orthodontic aligning archwires.

The forces produced by 10 orthodontic archwires were measured in a simulated clinical situation and also with the wires in simple three point loading. All tests were made to a maximum deflection of 3 mm. At 1.5 mm deflection the forces exerted when each wire formed part of a fixed appliance ranged from 1.5 to 8.3 N. When the same wires were used as simple beams the forces exerted ranged from 0.3 to 3.0 N. The findings indicate that the forces generated by orthodontic mechanisms cannot be calculated from straightforward physical principles.

Alloys↗
PubMed2001

Exertional dyspnea as initial manifestation of Takayasu's arteritis--a case report and literature review.

BACKGROUND: Takayasu's arteritis is a chronic systemic inflammatory disease that usually affects the aorta, its primary branches and occasionally the pulmonary and coronary arteries. Female gender in reproductive age and Asian origin are known factors associated with higher disease prevalence. The clinical manifestations vary considerably and are typically caused by limb or organ ischemia illness and fever. The estimated incidence rate in the western world is 2.6 cases per million persons per year. Occasionally, exertional dyspnea can be the sole primary clinical manifestation of Takayasu's arteritis. CASE PRESENTATION: We report the case of a 57-year-old woman who was referred to our institution with increasing exertional dyspnea caused by pulmonary artery involvement in Takayasu's arteritis. In a review of the literature we discuss demographic data, clinical and radiographic findings and available therapeutic options. CONCLUSIONS: Dyspnea due to pulmonary artery involvement can be the initial symptom of Takayasu's arteritis. Simple clinical tests, including a complete pulse-status and blood pressure measuring at both arms can lead to the right diagnosis and should always be done beyond the auscultation of the heart and lungs in patients with dyspnea.

Journal Article↗
PubMed2006

Forces exerted during exercises by patients with adolescent idiopathic scoliosis wearing fiberglass braces.

OBJECTIVE: To quantify and compare the forces exerted by scoliosis patients in fiberglass braces during exercises usually prescribed in departments where casts are made. The exercises are intended to increase corrective forces, activate muscles, stimulate ventilation and help the patient psychologically. SETTING: Outpatient care. PATIENTS: 17 consecutive adolescent patients wearing fiberglass brace for idiopathic scoliosis. INTERVENTIONS: Exercises (kyphotization, rotation, "escape from the pad") in different positions (sitting, supine, on all fours). MAIN OUTCOME MEASURE: Pressure detected by the F-Socket System between the rib hump and the pad of the brace. RESULTS: In static and dynamic conditions, the position adopted did not alter the total pressure exerted by the brace, although the part of the sensor stimulated did vary. Kyphotization and rotation exercises produced a significant increase of pressure (+ 58.9% and +29.8%, respectively); however, the "escape from the pad" exercise, despite its name, did not produce any significant variation of pressure. CONCLUSION: Exercises in the brace allow adjunctive forces to be applied on soft tissues and through them, presumably on the spine. Different exercises can be chosen to obtain different actions. Physical exercises and sporting activities are useful in mechanical terms, although other important actions should not be overlooked.

Journal Article↗
PubMed2006

Human CD4+ T lymphocytes with increased intracellular cAMP levels exert regulatory functions by releasing extracellular cAMP.

We have previously shown that cholera toxin (CT) and other cAMP-elevating agents induce up-regulation of the inhibitory molecule CTLA-4 on human resting T lymphocytes. In this study, we evaluated the function of these cells. We found that purified human CD4(+) T lymphocytes pretreated with CT were able to inhibit proliferation of autologous PBMC in a dose-dependent manner. It is interesting that this phenomenon was not mediated by inhibitory cytokines such as IL-10, IL-4, or TGF-beta but was in part caused by the release of extracellular cAMP by the CD4(+) T lymphocytes. Purified CD4(+) T cells pretreated with forskolin, a transient cAMP inducer, or with dibutyryl cAMP, an analog of cAMP, did not exert suppressive functions, suggesting that a sustained production of cAMP, such as that induced by CT, was required to identify a novel regulatory function mediated by CD4(+) T cells. Our results show that CD4(+) T lymphocytes can exert regulatory functions through the release of extracellular cAMP and that the cyclic nucleotide acts as a primary messenger, which could play a biological role in the modulation of immune responses.

CD4-Positive T-Lymphocytes↗
PubMed1993

The steroid antagonist RU486 exerts different effects on the glucocorticoid and progesterone receptors.

To determine whether the steroid antagonist RU486 mediates its antiglucocorticoid and antiprogestin activities by the same or different receptor mechanisms, a direct comparison of RU486 interaction with glucocorticoid (GR) and progesterone (PR) receptors was made. The effects of RU486 on transformation of GR and PR 8-10S complexes in the intact cell and in vitro were analyzed by sucrose density gradient centrifugation, and the in vitro stability of receptor-heat shock protein-90 interactions was analyzed by coimmunoprecipitation. Compared to agonist, RU486 binding produced a reduction in the amount of GR converted from 8S to 4S and stabilized the GR-heat shock protein-90 complex. By contrast, PR-RU486 complexes were transformed both in vitro and in the intact cell to the same extent as receptor-agonist complexes. PR-RU486 complexes sedimented at 5-6S, whereas PR-R5020, GR-RU486, and GR-agonist complexes sedimented at 4S. The portion of GR that undergoes nuclear transformation when bound to RU486 was examined for binding to the glucocorticoid-progesterone response element of the mouse mammary tumor virus by an immunoprecipitation assay. The nuclear-transformed GR-RU486 complex bound the glucocorticoid-progesterone response element with the same affinity as the nuclear-transformed GR-triamcinolone acetonide complex. The electrophoretic mobilities of GR-RU486 complexes and GR-agonist complexes were the same, as determined by gel retardation assay. These results suggest that RU486 exerts its antiglucocorticoid activity at two levels of receptor action: prevention of complete GR transformation and alteration of a step subsequent to GR-DNA binding. As an antiprogestin, RU486 action is exerted predominantly at a post-DNA-binding step.

Animals↗
PubMed1995

Somatostatin-14 and its analog octreotide exert a cytostatic effect on GH3 rat pituitary tumor cell proliferation via a transient G0/G1 cell cycle block.

Somatostatin (SRIF) and its analogs exert potent inhibitory effects on hormonal hypersecretion. In addition, they have been demonstrated to inhibit the proliferation of various cell lines as well as the growth of some endocrine tumors in vivo. To evaluate the action of SRIF and its analog octreotide on the proliferation and cell cycle kinetics of endocrine cells, we investigated their effect on GH3 rat pituitary tumor cells, a GH-producing cell line. Using flow cytometric DNA analysis with propidium iodide staining, we found that octreotide inhibits the proliferation of synchronized GH3 cells, achieving a maximal reduction, compared to controls, of 19.4 +/- 5.3% and 22.4 +/- 5.1% with 100 ng/ml and 1000 ng/ml octreotide, respectively (P < 0.05). This effect was demonstrated to be due to a block in progression from the G0/G1 phase to the S phase of the cell cycle. This was most evident after 24 h of exposure to 100 ng/ml octreotide, at which time there was a 7.1 +/- 1.4% increase in cells in G0/G1 (P < 0.01) and a 6.6 +/- 1.3% decrease in cells in S phase (P < 0.01). However, unless octreotide was replenished, this effect was transient and overcome by 36-48 h. No apoptosis was seen, and trypan blue studies confirmed that cell death by necrosis did not occur. A single exposure to native SRIF-14 had little effect, but a G0/G1 cell cycle block and inhibition of proliferation were seen if SRIF was regularly replenished. We conclude that SRIF and octreotide exert a cytostatic effect on GH3 cells by causing a partial G0/G1 cell cycle block. These findings suggest that the actions of SRIF and octreotide occur through signal transduction pathways that act predominantly on downstream regulators.

Animals↗
PubMed2006

Low-dose rosiglitazone exerts an antiinflammatory effect with an increase in adiponectin independently of free fatty acid fall and insulin sensitization in obese type 2 diabetics.

BACKGROUND: We have previously demonstrated an early and potent antiinflammatory effect of troglitazone and rosiglitazone. HYPOTHESIS: Because inflammatory mediators interfere with insulin signal transduction, we have now hypothesized that rosiglitazone exerts an initial antiinflammatory effect independently of its metabolic actions including the suppression of the plasma concentration of free fatty acids (FFAs), insulin, and glucose after which insulin sensitization occurs. PATIENT AND METHODS: Fourteen patients with type 2 diabetes were included in the study. Eight patients were given 2 mg daily of rosiglitazone for 6 wk, whereas the other six patients were given a placebo for the same period. RESULTS: After a 2-mg dose of rosiglitazone, plasma FFAs, insulin, and glucose concentrations and homeostasis model assessment of insulin resistance did not change. Plasma C-reactive protein, serum amyloid A, and matrix metalloproteinase concentrations fell significantly at wk 1 and continued to be significantly lower than the baseline levels by 25, 29, and 24%, respectively, at wk 6. Leukocyte count was significantly lower at wk 6 after rosiglitazone, whereas there was no change in the control group. Plasma adiponectin concentrations increased significantly at wk 2 and continued to increase during the treatment period with rosiglitazone. Resistin concentrations fell significantly by 10% at wk 6 only. There were no changes in any of these indices in the placebo group. CONCLUSIONS: A low dose of rosiglitazone exerts an early and potent antiinflammatory effect with an increase in adiponectin and a fall in resistin concentrations without causing any metabolic changes (fall in plasma glucose, FFAs, and insulin concentrations) over a 6-wk period. The increase in adiponectin and the decrease in resistin after rosiglitazone are thus related primarily to its antiinflammatory effects rather than its metabolic actions. These observations have implications in relation to the mode of action of this drug as an insulin-sensitizing agent and also its use as a potential antiinflammatory and antiatherogenic drug in the future.

Adiponectin↗
PubMed1999

The antigonadotropic activity of a 19-nor-progesterone derivative is exerted both at the hypothalamic and pituitary levels in women.

We have previously shown in postmenopausal women that a 19-nor-progesterone derivative, nomegestrol acetate (NOMA) had a strong antigonadotropic activity and that this effect was not mediated via the androgen receptor. The aim of the present study was to further assess the action of this progestin on gonadotropin secretion in women. To demonstrate at which level of the hypothalamo-pituitary-ovarian axis the gonadotropin inhibition was exerted, 10 normally cycling (NC) women, 3 women with a gonadotropin-independent ovarian function [McCune-Albright (MCA) syndrome], and 5 women with functional hypothalamic amenorrhea (FHA) participated in the study. NC women were treated orally with 5 mg NOMA for 21 days, after one control cycle. Plasma estradiol (E2) and progesterone, LH, and FSH levels were measured during each cycle. A frequent sampling study (every 10 min for 4 h), followed by a classic GnRH test (100 microg, i.v.), was performed on day 11. Women with MCA were studied before, during NOMA, and after long-acting GnRH agonist administration. In women with FHA, pulsatile GnRH (20 microg s.c., every 90 min) was given for two cycles with or without NOMA (5 mg for 21 days). In all NC women, ovulation was suppressed by NOMA. Mean plasma LH levels, LH pulse frequency, and the LH response to exogenous GnRH were significantly decreased. In MCA, neither NOMA nor GnRH agonist modified multiple ovarian cysts on ultrasound or plasma E2, levels which remained elevated, ruling out a direct ovarian effect. In FHA, pulsatile GnRH administration recreated a normal ovulatory menstrual cycle. Addition of NOMA prevented the increase of plasma E2, decreased the amplitude of LH pulses, and prevented ovulation. In view of this unexpected action of NOMA at the pituitary level, seven samples of normal human female pituitaries were tested for the presence of progesterone receptor (PR) using a double labeling immunocytochemical technique. The presence of PR was detected in the seven human pituitary tissues. In addition, PR was found to be expressed only in gonadotroph cells. In conclusion, NOMA, a 19-nor-P derivative, has a potent antigonadotropic activity exerted at the hypothalamic level, inhibiting ovulation in NC women. In women with FHA, NOMA decreased the gonadotropin stimulation induced by pulsatile GnRH administration. According to the presence of PR in gonadotroph cells of normal human pituitaries, 19-nor-progesterone derivatives may also act on the gonadotropin secretion at the pituitary level.

Adolescent↗
PubMed1997

Cardiac cephalgia: a treatable form of exertional headache.

We report two patients with exertional headaches beginning with vigorous exercise and relieved by rest. Neurologic evaluation and neuroimaging were normal in both. During exercise stress testing, the onset of the patients' typical headaches correlated with ECG changes indicative of myocardial ischemia. In both patients coronary angiography revealed three-vessel disease, and myocardial revascularization procedures were followed by complete resolution of headaches. Based on these patients, and a review of prior similar reports, we conclude that myocardial ischemia is a rare and treatable cause of exertional headache. Accurate diagnosis is critical to controlling headaches and preventing myocardial infarction.

Aged↗
PubMed2002

Partner telomeres during anaphase in crane-fly spermatocytes are connected by an elastic tether that exerts a backward force and resists poleward motion.

As chromosomes move polewards during anaphase in crane-fly spermatocytes, trailing arms commonly stretch backwards for a brief time, as if tethered to their partners. To test that notion, a laser microbeam was used to sever trailing arms and thereby release telomere-containing arm segments (called acentric fragments because they lack kinetochores) from segregating chromosomes. Analysis of the movement of acentric fragments after their release provided clear evidence that previously conjoined partners were indeed tethered at their telomeres and that tethers exerted backward forces that were sufficient to move the fragment across the equator and into the opposite half-spindle. To address concerns that tethers might be artifacts of in vitro cell culture, spermatocytes were fixed in situ, and stretched arms within fixed cells provided strong evidence for tethers in vivo. The substantial resistance that tethers impose on the poleward movement of chromosomes must normally be over-ridden by the poleward 'pulling' forces exerted at kinetochores. In spermatocytes, poleward forces are supplied primarily by the 'traction fibers' that are firmly attached to kinetochores through end-on attachments to the plus ends of kinetochore microtubules.

Anaphase↗
PubMed1983

Use of separate hand locations to calculate ground reaction force exerted on a vaulting pole.

A model was developed to permit calculation of the force exerted by the ground on a vaulting pole given the flexibility characteristics of the pole, the grip height of the upper hand, and the coordinates of each of the two hands relative to the base of the pole. The flexural rigidity of the pole was assumed constant throughout the length of the pole and not subject to hysteresis or dynamic loading effects. The model was based on the following rationale: knowing the initial angle of the base of the pole (beta 0) and the force vector (F1) exerted by the ground on the pole, it was possible to estimate the shape of the pole and the coordinates of the two hands following an iterative procedure. Conversely, it was possible to find a combination of beta 0 and F1 that made the pole fit two specified hand locations.

Biomechanical Phenomena↗
PubMed2003

Perceived exertion in fatiguing illness: civilians with chronic fatigue syndrome.

PURPOSE: It has been reported that ratings of perceived exertion (RPE) are elevated in chronic fatigue syndrome (CFS). However, methodological limitations have rendered this conclusion suspect. The purpose of the present investigation was to examine RPE during exercise in civilians with CFS by comparing subjects at both absolute exercise stage and relative oxygen consumption reference criteria. METHODS: A sample of 39 civilian females (N = 19 CFS, 34 +/- 7 yr; N = 20 healthy controls, 33 +/- 7 yr) underwent a maximal exercise test on a treadmill. RPE were obtained during the last 15 s of each 3-min stage using Borg's 6-20 scale. RESULTS: There were no significant differences in peak [OV0312]O(2), RER, or RPE. However, controls exercised longer (20.0 +/- 1.1 vs 15.9 +/- 1.1 min, P = 0.01, healthy vs CFS) and had higher peak HR (183 +/- 3 vs 174 +/- 2 bpm, P = 0.03, healthy vs CFS). Civilians with CFS reported higher RPE at stages 3 through 5 compared with controls (F(3,111)= 3.6,P = 0.017). Preexercise fatigue ratings were not a significant predictor of perceived exertion during exercise. There were no group differences (F(1,37)= 1.9, P = 0.17) when RPE were expressed relative to peak [OV0312]O(2). CONCLUSIONS: Our results show that RPE are greater in civilians with CFS when the data are expressed in terms of absolute exercise intensity. However, by examining RPE relative to a common maximum (i.e., peak [OV0312]O(2)) no differences were observed. The findings of the present investigation challenge the notion that RPE are dysregulated in CFS.

Adult↗