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The purpose of this study was to compare O[2] uptake (VO[2]) and muscle electromyography activity kinetics during moderate and severe exercise to test the hypothesis of progressive recruitment of fast-twitch fibers in the explanation of the VO[2] slow component. After an incremental test to exhaustion, 7 trained cyclists (mean +/- SD, 61.4 +/- 4.2 ml x min[-1] x kg[-1]) performed several square-wave transitions for 6 min at moderate and severe intensities on a bicycle ergometer. The VO[2] response and the electrical activity (i.e., median power frequency, MDF) of the quadriceps vastus lateralis and vastus medialis of both lower limbs were measured continuously during exercise. After approximately 2 to 3 min of exercise onset, MDF values increased similarly during moderate and severe exercise for almost all muscles whereas a VO[2] slow component occurred during severe exercise. There was no relationship between the increase of MDF values and the magnitude of the VO[2]slow component during the severe exercise. These results suggest that the origin of the slow component may not be due to the progressive recruitment of fast-twitch fibers. [ABSTRACT FROM AUTHOR]

Inconsistencies about dynamic asymmetry between the on- and off-transient responses in VO2 are found in the literature. Therefore the purpose of this study was to examine VO2on- and off-transients during moderate- and heavy-intensity cycling exercise in trained subjects. Ten men underwent an initial incremental test for the estimation of ventilatory threshold (VT) and, on different days, two bouts of square-wave exercise at moderate (VT) intensities. VO2 kinetics in exercise and recovery were better described by a single exponential model (VT). For moderate exercise, we found a symmetry of VO2 kinetics between the on- and off-transients (i.e., fundamental component), consistent with a system manifesting linear control dynamics. For heavy exercise, a slow component superimposed on the fundamental phase was expressed in both the exercise and recovery, with similar parameter estimates. But the on-transient values of the time constant were appreciably faster than the associated off-transient, and independent of the work rate imposed (VT). Our results do not support a dynamically linear system model of VO2 during cycling exercise in the heavy-intensity domain. [ABSTRACT FROM AUTHOR]

Aim: Investigate the kinetics of oxygen uptake during moderate and high intensity exercise in prepubertal children of different aerobic capacity.Methods: Ten well-trained (T) and 10 untrained (U) prepubertal children performed two constant-power tests at intensities corresponding to 80% of ventilatory threshold and 90% of the maximal aerobic power. Gas exchange was evaluated during each test.Results: They indicate: (1) a similar time constant for V˙O2 (τ1) between moderate and heavy exercise intensity for the two groups. (2) No significant difference for τ1 between U and T for moderate (U, 29.5 ± 14.0 s; T, 28.2 ± 10.2 s; NS) and heavy exercise (U, 24.0 ± 6.1 s; T, 27.4 ± 6.8 s; NS).Conclusion: The data suggested no effect of endurance training on oxygen uptake kinetics at the onset of exercise in children. [Copyright &y& Elsevier]

STUDY DESIGN.: Case report. OBJECTIVE.: To illustrate the usefulness of broad-range bacterial polymerase-chain-reaction (PCR) testing in osteoarticular infections by Capnocytophaga canimorsus. SUMMARY OF BACKGROUND DATA.: C. canimorsus is a Gram-negative bacillus that was first identified in 1976. It is a normal inhabitant of the oral mucosa of dogs (26%) and cats (15%). The main clinical patterns are septicemia, which may cause fatal septic shock (in 30% of cases) but arthritis and discitis are possible. C. canimorsus is susceptible to many antimicrobials including [beta]-lactam antibiotics. METHODS.: About a case report of 54-year-old man transferred to our institution for discitis, we discuss about PCR for C. canimorsus discitis diagnosis. RESULTS.: At admission, the only abnormal physical finding was global pain and stiffness of the lumbar spine. Radiographs of the lumbar spine and pelvis showed lumbar spondylosis, degenerative disc disease, and previously known degenerative facet joint disease. Magnetic resonance imaging indicated L3-L4 discitis with damage to both vertebrae and adjacent discs. Findings were negative from blood and urine cultures, serological tests for the HIV and brucellosis, and sputum tests for Mycobacterium tuberculosis. A percutaneous biopsy of the L3-L4 disc was performed but the bacteriological studies recovered no organisms. A second needle biopsy was performed for broad-range 16S rDNA PCR testing, which identified C. canimorsus. CONCLUSION.: Broad-range PCR provided the microbiological diagnosis of culture-negative discitis in our patient. Broad-range PCR should be considered in patients with culture-negative osteoarticular infections. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the usefulness of the polymyalgia rheumatica (PMR) activity score (PMR-AS) in guiding adjustment of glucocorticoid (GC) dosage., Methods: Rheumatologists prospectively included patients receiving GC therapy for PMR. At each visit, they assessed disease activity using a visual analog scale for physician's global assessment (VASph) and recorded whether a flare was diagnosed and/or the GC dosage was changed. In each patient, the PMR-AS was calculated using the formula of Leeb and Bird: C-reactive protein (mg/dl) + VAS pain score (0 to 10) + VASph (0 to 10) + (morning stiffness in min × 0.1) + elevation of upper limbs (0-3). We evaluated the correlation between PMR-AS and GC dosage changes in the group already treated with GC., Results: We included 89 patients (mean age 74.6 ± 6.2 yrs; disease duration 1.6 ± 2.2 yrs), who had a total of 149 visits. PMR-AS was available for 137 visits. Of those, 124 involved patients already treated with GC, and 13 patients who started GC treatment. The Spearman correlation coefficient between PMR-AS values and GC dosage change was 0.58 (p < 0.001). In the group already treated with GC, when the PMR-AS was higher than 20, GC dosages were never decreased. When the PMR-AS was between 10 and 20, GC dosages were decreased in 4 patients, unchanged in 4, and increased by < 5 mg in 4 patients. When PMR-AS was < 10, GC dosages were generally decreased., Conclusion: The PMR-AS is helpful for diagnosing flares of PMR and may also assist in everyday practice to decide how to change the GC dosage.

Aim: It is well established that altering O2 delivering to contracting skeletal muscle affects human performance. In this respect, a reduced O2 supply (e.g., hypoxia) increases the rate of muscle fatigue. This study aimed to determine the effects of moderate hypoxia and exercise intensity on oxygen uptake (VO2) and cardiac output (CO) kinetics during moderate [below the ventilatory threshold (VT)] and heavy (above VT) constant work rate cycling exercises., Methods: Eight trained males (age, mean+/-SD, 22+/-3 years; height 182+/-5 cm; body mass 71+/-12 kg) performed at the same relative intensity in normoxic (FIO2=0.21) and hypoxic (FIO2=0.13) conditions moderate and heavy exercises during which pulmonary gas exchange was determined breath-by-breath and CO was monitored beat-by-beat with Doppler echocardiography., Results: The rate of increase (t63%, corresponding to time constant and time delay of a monoexponential response) in CO was significantly faster than that of VO2 in 3 out of 4 experimental conditions (p<0.05). Moreover VO2 kinetics were significantly slowed by hypoxia and speeded by exercise intensity, while CO responses were unaffected by such conditions. A slowed CO response was apparent in hypoxia compared to normoxia (p>0.05) in heavy exercise., Conclusions: These results suggest an absence of coupling between CO and VO2 kinetics, and that cardiorespiratory O2 delivery is likely different at exercise onset as a function of exercise intensity and FIO2.

Inconsistencies about dynamic asymmetry between the on- and off-transient responses in VO2 are found in the literature. Therefore the purpose of this study was to examine VO2 on- and off-transients during moderate- and heavy-intensity cycling exercise in trained subjects. Ten men underwent an initial incremental test for the estimation of ventilatory threshold (VT) and, on different days, two bouts of square-wave exercise at moderate (VT) intensities. VO2 kinetics in exercise and recovery were better described by a single exponential model (VT). For moderate exercise, we found a symmetry of VO2 kinetics between the on- and off-transients (i.e., fundamental component), consistent with a system manifesting linear control dynamics. For heavy exercise, a slow component superimposed on the fundamental phase was expressed in both the exercise and recovery, with similar parameter estimates. But the on-transient values of the time constant were appreciably faster than the associated off-transient, and independent of the work rate imposed (VT). Our results do not support a dynamically linear system model of VO2 during cycling exercise in the heavy-intensity domain.