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Purpose: The Wingate anaerobic test measures the maximum anaerobic capacity of the lower limbs. The energy sources of Wingate test are dominated by anaerobic metabolism (~ 80%). Chronic high altitude exposure induces adaptations on skeletal muscle function and metabolism. Therefore, the study aim was to investigate possible changes in the energy system contribution to Wingate test before and after a high-altitude sojourn.Methods: Seven male climbers performed a Wingate test before and after a 43-day expedition in the Himalaya (23 days above 5.000 m). Mechanical parameters included: peak power (PP), average power (AP), minimum power (MP) and fatigue index (FI). The metabolic equivalents were calculated as aerobic contribution from O2 uptake during the 30-s exercise phase (WVO2), lactic and alactic anaerobic energy sources were determined from net lactate production (WLa) and the fast component of the kinetics of post-exercise oxygen uptake (WPCr), respectively. The total metabolic work (WTOT) was calculated as the sum of the three energy sources.Results: PP and AP decreased from 7.3 ± 1.1 to 6.7 ± 1.1 W/kg and from 5.9 ± 0.7 to 5.4 ± 0.8 W/kg, respectively, while FI was unchanged. WTOT declined from 103.9 ± 28.7 to 83.8 ± 17.8 kJ. Relative aerobic contribution remained unchanged (19.9 ± 4.8% vs 18.3 ± 2.3%), while anaerobic lactic and alactic contributions decreased from 48.3 ± 11.7 to 43.1 ± 8.9% and increased from 31.8 ± 14.5 to 38.6 ± 7.4%, respectively.Conclusion: Chronic high altitude exposure induced a reduction in both mechanical and metabolic parameters of Wingate test. The anaerobic alactic relative contribution increased while the anaerobic lactic decreased, leaving unaffected the overall relative anaerobic contribution to Wingate test. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyze the physiological features of peripheral blood mononuclear cells ( PBMCs) isolated from healthy female trekkers before and after physical activity carried out under both normoxia (low altitude, < 2000 m a.s.l.) and hypobaric hypoxia (high altitude, > 3700 m a.s.l.). The experimental design was to differentiate effects induced by exercise and those related to external environmental conditions. PBMCs were isolated from seven female subjects before and after each training period. The PBMCs were phenotypically and functionally characterized using fluorimetric and densitometric analyses, to determine cellular activation, and their intracellular Ca2+ levels and oxidative status. After a period of normoxic physical exercise, the PBMCs showed an increase in fully activated T lymphocytes ( CD3+ CD69+) and a reduction in intracellular Ca2+ levels. On the other hand, with physical exercise performed under hypobaric hypoxia, there was a reduction in T lymphocytes and an increase in nonactivated B lymphocytes, accompanied by a reduction in O2− levels in the mitochondria. These outcomes reveal that in women, low- to moderate-intensity aerobic trekking induces CD69 T cell activation and promotes anti-stress effects on the high-altitude-induced impairment of the immune responses and the oxidative balance. [ABSTRACT FROM AUTHOR]

Human exposure to altitude is a model to study the role of oxygen in different areas of physiology and pathophysiology. The aim of this study was to evaluate whether a short exposure to hypoxia (5 days) combined with exercise, at altitude ranging from 900 m above sea level to 5895 m above sea level (Kilimanjaro Expedition) can modify seminal and reproductive hormonal parameter levels in human beings. During the ascent, blood oxygen saturation at 3.848 m above sea level was found to be decreased when compared to sea level ( P < 0.02). The sperm forward motility at sea level after the expedition showed a significant reduction ( P < 0.02). There were no changes in other seminal parameters among those compared. Determination of the hormonal plasma concentrations showed that baseline values of follicle-stimulating hormone, total testosterone, prolactin and oestradiol were unchanged at sea level after the hypoxic experience, with respect to baseline values at sea level. On the other hand, luteinising hormone levels after altitudes trekking significantly increased compared to levels before the expedition ( P < 0.05). Because of the short-term exposure, we can assume that the reduced forward motility described here may result from the effects of the acute altitude hypoxia on spermatozoa during the epididymal transit where they mature acquiring their motility. [ABSTRACT FROM AUTHOR]

Purpose: We investigated the effects of moderate-intensity training at low and high altitude on VO2 and QaO2 kinetics and on myosin heavy-chain expression (MyHC) in seven women (36.3 yy ± 7.1; 65.8 kg ± 11.7; 165 cm ± 8) who participated in two 12- to 14-day trekking expeditions at low (598 m) and high altitude (4132 m) separated by 4 months of recovery.Methods: Breath-by-breath VO2 and beat-by-beat QaO2 at the onset of moderate-intensity cycling exercise and energy cost of walking (Cw) were assessed before and after trekking. MyHC expression of vastus lateralis was evaluated before and after low-altitude and after high-altitude trekking; muscle fiber high-resolution respirography was performed at the beginning of the study and after high-altitude trekking.Results: Mean response time of VO2 kinetics was faster (P = 0.002 and P = 0.001) and oxygen deficit was smaller (P = 0.001 and P = 0.0004) after low- and high-altitude trekking, whereas ˙ QaO2 kinetics and Cw did not change. Percentages of slow and fast isoforms of MyHC and mitochondrial mass were not affected by low- and high-altitude training. After training altitude, muscle fiber ADP-stimulated mitochondrial respiration was decreased as compared with the control condition (P = 0.016), whereas leak respiration was increased (P = 0.031), leading to a significant increase in the respiratory control ratio (P = 0.016).Conclusions: Although training did not significantly modify muscle phenotype, it induced beneficial adaptations of the oxygen transport-utilization systems witnessed by faster VO2 kinetics at exercise onset. [ABSTRACT FROM AUTHOR]

The study investigated the effect of prolonged hypoxia on central [i.e., cardiovascular oxygen delivery (QaO2)] and peripheral (i.e., O2 utilization) determinants of oxidative metabolism response during exercise in humans. To this aim, seven male mountaineers were examined before and immediately after the Himalayan Expedition Interamnia 8000-Manaslu 2008, lasting 43 days, among which, 23 days were above 5,000 m. The subjects showed a decrease in body weight (P < 0.05) and of power output during a Wingate Anaerobic test (P < 0.05) and an increase of thigh cross-sectional area (P < 0.05). Absolute maximal O2 uptake (VO2max) did not change. The mean response time of 402 kinetics at the onset of step submaximal cycling exercise was reduced significantly from 53.8 s ± 10.9 to 39.8 s ± 10.9 (P < 0.05), whereas that of QaO2 was not. Analysis of single fibers dissected from vastus lateralis biopsies revealed that the expression of slow isoforms of both heavy and light myosin subunits increased, whereas that of fast isoforms decreased. Unloaded shortening velocity of fibers was decreased significantly. In summary, independent findings converge in indicating that adaptation to chronic hypoxia brings about a fast-to-slow transition of muscle fibers, resulting in a faster activation of the mitochondrial oxidative metabolism. These results indicate that a prolonged and active sojourn in hypoxia may induce muscular ultrastructural and functional changes similar to those observed after aerobic training. [ABSTRACT FROM AUTHOR]

Chronic hypoxia is related to many pathological conditions: aging, heart and respiratory failure, sleep apneas, smoke, chronic obstructive pulmonary disease (COPD), diabetes, hypertension and arteriosclerosis, all characterized by reductions of sleep-related erections (SREs) and by erectile dysfunction (ED). Sleep-related erections occur naturally during rapid eye movement (REM) sleep in sexually potent men. Hypoxia is also a physiological condition at altitude. The level of inspired oxygen decreases progressively with the increase of altitude; for this reason, this study was performed to evaluate the relationship of SREs with hypoxic environment. SREs have been recorded by an erectometer (RigiScan) on three mountain climbers (mean age: 32.5) during a 26-day stay at an altitude ranging from 2000 to 5600 m above sea level. Twenty-four records have been made at progressively increasing altitudes. A data analysis was carried out on a statistical mean of the three values of each variable and an analysis of variance (ANOVA) and Newman–Keuls test were carried out for multiple comparison among groups. At altitudes over 4450 m, we found lack of rigidity at 80–100% and 60–79%. Mean % of rigidity and rigidity time of 80–100% (tip and base) decreased progressively with altitude. No significant reductions were shown in rigidity time at 0–19% and at 20–39% (tip and base), of total number, of total and mean duration of SREs. Pathological rigidometric records at high altitude in sexually potent men at sea level clarify the primary role of hypoxia in physiopathological ED pathway.International Journal of Impotence Research (2007) 19, 496–500; doi:10.1038/sj.ijir.3901560; published online 31 May 2007 [ABSTRACT FROM AUTHOR]