Alain Duvallet

Changes in blood leucocyte populations induced by acute maximal and chronic submaximal exercise

SummaryAbsolute (×103·mm−3) or relative (%) numbers of blood leucocyte types (monocytes, lymphocytes, neutrophils) and lymphocyte subsets (T11+, T4+, T8+, B1+, and NKH1+) reacting with specific monoclonal antibodies were determined at rest, immediately after maximal exercise on a treadmill, in six controls (C), and in six young cyclists before training (BT) and after 5 months of training (AT). Maximal exercise significantly increased the absolute number (mobilization) of virtually all the types of leucocytes and subsets of lymphocytes in C, BT and AT subjects. In these subjects mobilization of natural killer cells (NKH1+) and cytotoxic/suppressor T lymphocytes (T8+) was greater than mobilization of the other leucocyte types and lymphocyte subsets; however, maximal exercise induced no significant changes in the relative numbers of any leucocyte types and lymphocyte subsets, except in the case of T4+ lymphocytes in AT cyclists. Chronic submaximal exercise induced increased mobilization of neutrophils and decreased mobilization of lymphocytes during maximal exercise, except in the case of B lymphocytes (B1+) and NKH1+ cells, and decreases in the absolute and relative number of neutrophils at rest. It remains to be seen how these results can explain the modifications of leucocyte activities noted in vitro after isolated or chronic exercise.

Cerebral adaptations to chronic anemia in a model of Erythropoietin deficient mice exposed to hypoxia

Anemia and hypoxia in rats result in an increase in factors potentially involved in cerebral angiogenesis. Therefore, the aim of this study was to assess the effect of chronic anemia and/or chronic hypoxia on cerebral cellular responses and angiogenesis in wild-type and anemic transgenic mice. These studies were done in erythropoietin-deficient mice (Epo-TAg(h)) in normoxia and following acute (one day) and chronic (14 days, barometric pressure = 420 mmHg) hypoxia. In normoxia, Epo-TAg(h) mice showed an increase in transcript and protein levels of hypoxia-inducible factor 1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF), erythropoietin receptors (EpoR), phospho-STAT-5/STAT-5 ratio, and neuronal neuronal nitric oxide synthase (nNOS) along with a higher cerebral capillary density. In wild-type (WT) mice, acute hypoxia increased all of the studied factors, while in chronic hypoxia, HIF-1alpha, EpoR, phospho-STAT-5/STAT-5 ratio, nNOS, and inducible NOS remained elevated, with an increase in capillary density. Surprisingly, in Epo-TAg(h) mice, chronic hypoxia did not further increase any factor except the nitric oxide metabolites, while HIF-1alpha, EpoR, and phospho-STAT-5/STAT-5 ratio were reduced. Normoxic Epo-TAg(h) mice developed cerebral angiogenesis through the HIF-1alpha/VEGF pathway. In acute hypoxia, WT mice up-regulated all of the studied factors, including cerebral NO. Polycythemia and angiogenesis occurred with acclimatization to chronic hypoxia only in WT mice. In Epo-TAg(h), the decrease in HIF-1alpha, VEGF proteins, and phospho-STAT-5 ratio in chronic hypoxia suggest that neuroprotective and angiogenesis pathways are altered.

Maximal aerobic power in patients with chronic low back pain: a comparison with healthy subjects

The objective of the study was to compare the maximal aerobic capacity of patients with chronic low back pain with healthy asymptomatic controls matched for age, gender and level of physical activity at work and during sports activities. Reported data in the literature with respect to aerobic capacity in patients with chronic low back pain are not conclusive. Nevertheless, based on the assumption that chronic low back pain leads to deconditioning, physical training programs are widely used as a treatment. A total of 70 patients with chronic low back pain and 70 healthy asymptomatic subjects completed questionnaires regarding demographics and performed a graded maximal exercise test until exhaustion on a cycle ergometer. The maximal aerobic power was measured by indirect calorimetry. Heart rate, respiratory exchange ratio and blood lactate levels were also measured. The test was considered maximal when VO2max achievement criteria were obtained. VO2max values were compared among groups. The absolute and normalized for weight values of VO2max measured in patients with chronic low back pain were significantly lower than that of the control group. Independent comparison between men and women showed that absolute values of VO2max are also significantly lower in men and women with chronic low back pain. Women reached absolute and normalized for weight VO2max values significantly lower than those of men, both in chronic low back pain and control group. In conclusion, chronic low back pain patients, especially women, seem to have a reduced aerobic capacity compared to healthy asymptomatic subjects.

Moderate exercise in hypoxia induces a greater arterial desaturation in trained than untrained men

During moderate exercise breathing a low inspired O2 fraction (FIO2), arterial O2 desaturation may depend on the fitness level. Seven trained (TM) and seven untrained men (UTM) cycled in normoxia and in hypoxia (FIO2=0.187, 0.173, 0.154, 0.13 and 0.117). We compared TM and UTM at submaximal intensities below the ventilatory threshold. Ventilatory variables were monitored and arterial oxygen saturation was measured by pulse oximetry. O2 saturation was not different between groups at sea level. In hypoxia, O2 saturation was lower in TM than in UTM at FIO2=0.154 (87.3 ± 2.9% vs 90.4 ± 1.5% at 90 W) and below. Both the ventilatory‐equivalent and the end‐tidal O2 pressure were lower in TM at sea level and at every FIO2, with the differences between TM and UTM becoming apparent at lower exercise intensity and increasing in magnitude as the severity of hypoxia increased. O2 saturation was correlated with the ventilatory parameters at every FIO2 and the correlations were stronger in severe hypoxia. These results demonstrate that a moderate exercise carried out in hypoxia, contrary to normoxic conditions, can lead to a greater arterial desaturation in TM compared with UTM. This phenomenon could be partly attributed to a relative hypoventilation in trained subjects.

Blood lactate accumulation in intermittent supramaximal exercise

SummaryBlood lactate accumulation rate and oxygen consumption have been studied in six trained male runners, aged 20 to 30 years. Subjects ran on a treadmill at a rate representing 172±5%

Blunting effect of hypoxia on the proliferation and differentiation of human primary and rat L6 myoblasts is not counteracted by Epo

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Prolonged expiration down to residual volume leads to severe arterial hypoxemia in athletes during submaximal exercise.

for four 45 s sessions, separated by 9 min rest periods. Oxygen consumption was measured throughout. Blood lactate was determined in samples taken from the ear and