Eduardo Garrido

Neuropsychological Functioning Associated with High-Altitude Exposure

This article focuses on neuropsychological functioning at moderate, high, and extreme altitude. This article summarizes the available literature on respiratory, circulatory, and brain determinants on adaptation to hypoxia that are hypothesized to be responsible for neuropsychological impairment due to altitude. Effects on sleep are also described. At central level, periventricular focal damages (leuko-araiosis) and cortical atrophy have been observed. Frontal lobe and middle temporal lobe alterations are also presumed. A review is provided regarding the effects on psychomotor performance, perception, learning, memory, language, cognitive flexibility, and metamemory. Increase of reaction time and latency of P300 are observed. Reduced thresholds of tact, smell, pain, and taste, together with somesthetic illusions and visual hallucinations have been reported. Impairment in codification and short-term memory are especially noticeable above 6,000 m. Alterations in accuracy and motor speed are identified at lower altitudes. Deficits in verbal fluency, language production, cognitive fluency, and metamemory are also detected. The moderating effects of personality variables over the above-mentioned processes are discussed. Finally, methodological flaws found in the literature are detailed and some applied proposals are suggested.

A new approach to the assessment of anaerobic metabolism: measurement of lactate in saliva.

OBJECTIVE: To test the hypothesis that saliva lactate concentrations may reflect those present in blood and that saliva lactate can be used as a very convenient and useful variable in the study of anaerobic metabolism. METHODS: Parallel determinations were made of lactate in saliva and in capillary blood samples, obtained at 3 min intervals from nine individuals during the performance of a maximum graded exercise test on a cycle ergometer against increasing workloads (from 25 up to a maximum of 300 W). Lactate determinations were done by means of an electroenzymatic method using 25 microliters samples in both types of fluids. RESULTS: For each situation, the concentration of lactate in saliva was shown to be about 15% of that in plasma but it followed the same pattern of evolution during the exercise test. A good correlation (r = 0.81) between blood and saliva lactate concentrations was found. The precision of the method was very good, with a coefficient of variation ranging (n = 10) between 2.2% for samples with very low lactate concentrations and 0.7% for sample with moderate lactate concentrations. Lactate appeared to be very stable in saliva over a period of 40 days after collection, when kept at 4 degrees C. The values obtained after this period were virtually identical to those shown in fresh samples. CONCLUSIONS: Determination of lactate in saliva can be used as an alternative to determination in blood, overcoming most of the drawbacks of the procedures being used at present, since the collection of the samples required no special expertise.

Heritability of running economy: a study made on twin brothers.

Abstract Running economy (RE), defined as the steady-state of oxygen uptake (V˙O2) for a given running velocity, is a factor of sports performance the genetic component of which has seldom been reported to date. We studied this component using a heritability index (HI) in a group of 32 male twins, 8 monozygotic (MZ) and 8 dizygotic (DZ) pairs, all sportsmen with similar perinatal and environmental backgrounds. Zygocity was determined by the identity of erythrocytic antigenic, protein and enzymatic polymorphism, and human leucocyte antigen serologic types between co-twins. The subjects exercised twice on a treadmill, once until exhaustion and again at submaximal intensities. Pulmonary gas exchange was measured continuously using an automatic analyser system during both tests. Blood samples were obtained during the recovery period to determine lactate concentrations. No significant differences were observed between MZ and DZ, in respect of RE at any speed or in maximal V˙O2 relative to body mass. Nevertheless, significant HI (P < 0.05) was found in maximal lactate concentrations (HI = 0.75) and in respiratory equivalent for oxygen at two speeds, 7 km · h−1 (HI = 0.71) and 8 km · h−1 (HI = 0.79), differences which probably suggest that there are differences in RE. In conclusion, we did not detect a genetic component in RE or in maximal oxygen uptake, but a genetic component for markers of anaerobic metabolism was present.

Cardiorespiratory response to exercise in elite Sherpa climbers transferred to sea level

Himalayan Sherpas are well known for their extraordinary adaptation to high altitude and some of them for their outstanding physical performance during ascents to the highest summits. To cast light on this subject, we evaluated the cardiorespiratory response during exercise at sea level of six of the most acknowledged Sherpa climbers, mean age (+/- SD) 37 (+/- 7) yr old. Continuous electrocardiogram and breath-by-breath pulmonary gas exchange until exhaustion were obtained by following the Bruce protocol. We detected a maximal oxygen uptake (VO2max) of 66.7 (+/- 3.7) mL-min-1.kg-1, maximal cardiac frequency of 199 (+/- 7) beats.min-1, and ventilatory anaerobic threshold at 62 (+/- 4) % of VO2max. These factors could help to explain the greater performance level shown by several elite climbers of this ethnic group. The high functional reserve demonstrated by this very select group of highlanders could be associated with natural selection and with special physiological adaptations probably induced by long-training in a hostile environment.

The death of Cajal and the end of scientific romanticism and individualism

Reference EPFL-ARTICLE-204183doi:10.1016/j.tins.2014.08.002View record in Web of Science Record created on 2014-12-30, modified on 2017-05-12

Normoxic ventilatory response in lowlander and Sherpa elite climbers

The differences in ventilatory response to exercise of some highland ethnic communities is a controversial issue. We have evaluated the differences in ventilatory response to exercise at sea level between two groups of elite climbers, four Himalayan Sherpas (S) and four Caucasian lowlanders (C), after descent from extreme altitude. All of them performed a progressive-intensity exercise test on a treadmill under normoxic conditions. Pulmonary gas exchange was obtained until exhaustion by means of an automatic gas-analyzer system. Significant differences in expired ventilation and carbon dioxide production were found between the two groups, the VE x VO2(-1) being lower in the S at rest (41.9 +/- 5) in comparison with C (48.7 +/- 9) (P < 0.05), higher at medium loads of the test (S = 28.2 +/- 4 vs. C = 25.7 +/- 2; P < 0.05) and reaching similar values at higher loads (S = 34.5 + 2 vs. C = 35.6 +/- 4; NS). We conclude that the special ventilatory response observed in these highlanders could explain their adaptation to altitude, allowing higher oxygen blood saturation at medium working loads and reducing the risk of neurological injury caused by a high ventilatory response when exercising at high intensity effort under extreme altitude environment.

Diferencias interindividuales en las concentraciones de cortisol plasmático tras una hora de ejercicio mixto aeróbico-anaeróbico

Introduction and objectives: The aim of the present study was to evaluate differences in plasma cortisol concentration in response to an intercalating aerobic-anaerobic exercise test in a group of physically active young people. Methods: Fourteen healthy young male volunteers performed a 40-minute exercise test at 50% of individual peak oxygen uptake on a cycle ergometer, maintaining a pedal rate of 60 r.p.m., during which they aimed to intercalate 4 explosive anaerobic phases of 30 seconds with a workload of 0.04 kg per kg of body mass at 10, 20, 30 and 40 minutes. After this first phase, and without stopping the exercise and maintaining the corresponding workload of 50% of peak oxygen uptake, the volunteers ended the exercise by pedaling at the maximum number of revolutions possible for 20 minutes. Cardiopulmonary parameters were continuously monitored and blood samples were obtained at rest, every 10 minutes during the test, and at 15 minutes during the recovery period. Results: Cardiopulmonary and metabolic responses were similar in all the participants during the test and the group tendency was to increase plasma cortisol levels significantly throughout the test (F = 5.16; p < 0.001). Plasma cortisol levels showed large interindividual differences (F = 6.74; p < 0.001). In 8 participants (57.1%), plasma cortisol levels increased during exercise and while in 6 (42.9%) minor changes with respect to resting values were observed. Conclusion: Substantial differences in plasma cortisol levels were found in a homogeneous group of young male volunteers during a successive aerobic-anaerobic exercise test, which may have implications in adaptation to exercise.