Egon Humpeler

Beneficial effects of exercising at moderate altitude on red cell oxygen transport and on exercise performance

The effect of a ascent to moderate altitude (2,300 m) and altitude training on the O2-transport properties of Hb and their possible consequences on tissue oxygenation during exercise were studied on six control and six training subjects. A rapid increase in P-50 values (+2.4 mm Hg, 0.32 kPa) was measured within one day after ascent. At the end of the stay at altitude (13th day) P-50 values were higher in subjects performing training than in controls. At altitude a slow but constant increase in 2,3-DPG, pyruvate kinase activity and reticulocyte count was found, which was more pronounced in training subjects as compared to controls. Ascent to altitude resulted in a decreased maximal performance capacity (−9%), but both groups recovered during the stay. In training subjects maximal exercise performance was increased after descent. Exercise at altitude was performed at a lower heart rate (controls: −10/min; training: −18/min) and at a lower lactate concentration (−4 mmol/l). These data indicate a positive effect of adaptation to altitude on exercise performance. Training itself shifts the ODC to the right and adds this effect to the effects of passive altitude adaptation on the O2-binding properties of hemoglobin.

Vacation at Moderate and Low Altitude Improves Perceived Health in Individuals with Metabolic Syndrome

BACKGROUND Recent data suggest that vacation may improve cardiovascular health, an effect possibly moderated by altitude. The aim of the present study was to study the effect of a 3-week vacation at moderate and low altitude on perceived health in individuals with increased cardiovascular risk. METHODS Seventy-two overweight males, both occupationally active and retired (mean age=56.6 +/- 7.2 years), with signs of metabolic syndrome were randomly assigned to identical sojourns at either moderate (1,700 m) or low (300 m) altitude and engaged in four 3- to 4-h heart-rate-controlled hiking tours per week. Perceived health was measured 2 weeks before vacation, at the beginning and end of vacation, and 7 weeks after vacation. RESULTS Fitness, recreational ability, positive and negative mood and social activities improved during vacation, independent of altitude and occupational status, although the day-to-day improvement in quality of sleep was delayed at moderate altitude. During the follow-up examinations, improvements in all reported aspects of health except for social activities were maintained. In comparison to retired individuals, active individuals showed a greater long-term improvement in social activities. CONCLUSION Vacation positively affects perceived health independent of altitude or occupational status in generally inactive overweight males.

Red cell oxygen transport in man in relation to gender and age

P50 values, the O2-partial pressure at 50% O2-saturation of hemoglobin, 2,3-DPG, hematological parameters and the plasma concentrations of sexual hormones were determined in 135 subjects of both sexes aged from 10 to 60 years. P50 was significantly higher in sexually mature women than in men, but did not differ between sexes before puberty and after menopause. In females P50 increased with sexual maturation by about 2 mmHg (0.27 kPa). RBC, Hb and Hct remained unchanged. In males Hb-O2-affinity, RBC, Hb and Hct increased with aging. In sexually mature females 2,3-DPG was significantly higher (2 mumol/gHb) than in males, although before puberty and postmaturity no difference was found. In males, 2,3-DPG increased slightly with maturation although P50 decreased. P50 values (pH = 7.4) correlated positively with red cell 2,3-DPG only when data from all groups were pooled (r = 0.330, P less than or equal to 0.0001). Hb was negatively correlated with P50 (r = 0.221, P less than or equal to 0.01). The data suggest a sex hormone and maturation induced influence in the development of the red cell O2-transport system. Estrogens seem to favour a decrease in Hb-O2-affinity rather than an elevation in O2-transport capacity, whereas androgens do the reverse.

Diminution of the temperature effect on the oxygen affinity of hemoglobin after prolonged hypothermia

The influence of temperature on the oxygen affinity of hemoglobin, expressed as half saturation tension, P50, was investigated in male Sprague Dawley rats, which had been exposed to a cold environment for about 12 h. P50-values were determined by equilibrating blood samples to a knownPO2 at different temperatures. The well known increase in oxygen affinity at low temperatures was observed, but after a longer hypothermic period this effect was diminished. This reduction of the temperature effect is manifested in a change of the ratio Δlog P50/ΔT from 0.022 in control experiments to 0.0115 in hypothermia. In cold adapted rats such an effect means a better oxygen supply to tissue at low body temperatures than in control animals. These changes in oxygen delivery after cold acclimatisation may partially be interpreted as the result of the decreased intraerythrocytic pH and elevated concentration of ATP found in the present study.

Effects of Hiking at Moderate and Low Altitude on Cardiovascular Parameters in Male Patients With Metabolic Syndrome: Austrian Moderate Altitude Study

OBJECTIVE Physical activity is a cornerstone in therapy for patients with metabolic syndrome. Walking and hiking in a mountain scenery represents an ideal approach to make them move. The Austrian Moderate Altitude Study (AMAS) 2000 main study is a randomized controlled trial to investigate the cardiovascular effects of hiking at moderate altitude on patients with metabolic syndrome compared with a control group at low altitude, to assess a potential altitude-specific effect. METHODS Seventy-one male patients with metabolic syndrome were randomly assigned to a moderate altitude group (at 1700 m), with 36 participants, or to a low altitude group (at 200 m), with 35 participants. The 3-week vacation program included 12 hiking tours (4 per week, average duration 2.5 hours, intensity 55% to 65% of heart rate maximum). Physical parameters, performance capacity, 24-hour blood pressure, and heart rate profiles were obtained before, during, and after the stay. RESULTS In both groups, we found a significant mean weight loss of -3.13 kg; changes in performance capacity were minor. Systolic, diastolic, and mean arterial pressures and circadian heart rate profiles were significantly reduced in both groups, with no differences between them. Consequently, the pressure-rate product was reduced as well. All study participants tolerated the vacation well without any adverse events. CONCLUSIONS A 3-week hiking vacation at moderate or low altitude is safe for patients with metabolic syndrome and provides several improvements in their cardiovascular parameters. The cardiovascular benefits achieved are more likely to be the result of regular physical activity than the altitude-specific effect of a mountain environment.

AMAS (Austrian Moderate Altitude Study)-2000: Effects of Hiking Holidays at Moderate Altitude on Immune System Markers in Persons with Metabolic Syndrome.

Abstract Recent studies have shown a strong association between indices of inflammation and metabolic Syndrome. Proinflammatory mediators like tumor necrosis factor-α may act as a trigger for insulin insensitivity. Therefore, patients with metabolic Syndrome might be at higher risk of insulin resistance when confronted with additional Stimuli of the immune system. These Stimuli are not restricted to the presence of pathogens but include environmental factors like physical exercise and hypoxemia as well. With respect to these interdependencies, one may assume higher risk for patients with metabolic Syndrome who perform physical exercise in alpine regions. We investigated the effects of a 3-weeks holiday with moderate sporting activities at moderate altitude (1700 m) on the conceiitrations of neopterin, tumor necrosis factor-α, serum soluble 75kD type TNF receptor (sTNF-R75), and interleukin-6 in vacationers with metabolic Syndrome. Only serum neopterin and sTNF-R75 concentrations transiently increased during the stay at moderate altitude compared to pre-altitude levels (P<0.05). Interestingly, after return to 500 m sea-level neopterin concentrations dropped beyond baseline concentrations (p<0.05). However, the variations in neopterin concentrations might not be of clinical relevance since they did not exceed the threshold indicating significant activation of the cellular immune system. We conclude that a 3-week sojourn at moderate altitude including individually adapted physical exercise does not represent accumulated risk factors in subjects with metabolic Syndrome.

Oxygen affinity of hemoglobin in postmenopausal women.

In a group of 12 postmenopausal women the P50-value (i.e. half saturation tension of oxygen) and other parameters of the red blood count were determined and compared with values of a male group of the same age. A small but significant difference could be found between the hematocrit values but no other values differed. In particular, the sex difference in oxygen affinity reported earlier does not exist in men and women on this age group.

Short Vacation Improves Stress-Level and Well-Being in German-Speaking Middle-Managers—A Randomized Controlled Trial

Stress in the work place has a detrimental effect on people’s health. Sufficient recovery is necessary to counteract severe chronic negative load reactions. Previous research has shown that vacationing for at least seven consecutive days provided an efficient recovery strategy. Yet, thus far, the effects of short vacations and the mode of vacation (whether at home or in a new environment) have rarely been studied. We investigated the immediate and long-term effects of a short vacation (four nights) on well-being and perceived stress and whether the mode of vacation impacted on these results. Data was obtained from 40 middle managers (67.5% men and 32.5% women). The intervention group (n = 20) spent a short vacation in a hotel outside their usual environment. The control group (n = 20) spent their vacation at home. Results indicated that one single short-term vacation, independent of the mode, has large, positive and immediate effects on perceived stress, recovery, strain, and well-being. Strain levels decreased to a greater extent in the intervention group compared to the control group. The effects can still be detected at 30 days (recovery) and 45 days (well-being and strain) post-vacation. Encouraging middle management employees to take short vacations seems to be an efficient health promotion strategy; environmental effects seem to play a minor role.