Validity of the 3 min step test in moderate altitude: environmental temperature as a confounder

The effects of normobaric and hypobaric hypoxia on cognitive performance and physiological responses: A crossover study

This partially randomised controlled, crossover study sought to investigate the effects of normobaric hypoxia (NH) and hypobaric hypoxia (HH) on cognitive performance, the physiological response at rest and after a 3-min step-test. Twenty healthy participants (10 females and 10 males, 27.6±6.2yrs, 73.6±13.7kg, 175.3±8.9cm) completed a cognitive performance test, followed by the modified Harvard-step protocol, in four environments: normobaric normoxia (NN; PiO2: 146.0±1.5mmHg), NH (PiO2: 100.9±1.3mmHg), HH at the first day of ascent (HH1: PiO2 = 105.6±0.4mmHg) and HH after an overnight stay (HH2: PiO2 = 106.0±0.5mmHg). At rest and/or exercise, SpO2, NIRS, and cardiovascular and perceptual data were collected. The cerebral tissue oxygenation index and the cognitive performance (throughput, accuracy, and reaction time) were not different between the hypoxic conditions (all p>0.05). In NH, SpO2 was higher compared to HH1 (ΔSpO2 NH vs HH1: 1.7±0.5%, p = 0.003) whilst heart rate (ΔHR NH vs HH2: 5.8±2.6 bpm, p = 0.03) and sympathetic activation (ΔSNSi NH vs HH2: 0.8±0.4, p = 0.03) were lower in NH compared to HH2. Heart rate (ΔHR HH1 vs HH2: 6.9±2.6 bpm, p = 0.01) and sympathetic action (ΔSNSi HH1 vs HH2: 0.9±0.4, p = 0.02) were both lower in HH1 compared to HH2. In conclusion, cognitive performance and cerebral oxygenation didn’t differ between the hypoxic conditions. SpO2 was only higher in NH compared to HH1. In HH2, heart rate and sympathetic activation were higher compared to both NH and HH1. These conclusions account for a PiO2 between 100–106 mmHg.

Stepping from Belgium to the United States and back: the conceptualization and impact of the Harvard Step Test, 1942-2012

PURPOSE

This article examines the contribution of the Belgian-American exercise physiologist Lucien Brouha in developing the Harvard Step Test (HST) at the'pioneering Harvard Fatigue Laboratory (HFL) during the Second World War and provides a better understanding of the importance of transnational relations concerning scientific progress.

METHOD

Analysis of sources in the University Archives of the State University in Liege (Belgium), the Archives and Documentation Centre of the Sportimonium at Hofstade (Belgium), the Harvard Business School Archives at Baker Library (Cambridge, MA), the Harvard Medical School Archives at Countway Library (Cambridge, MA), and the Brouha and Shaler private family archives (Sutton, VT).

RESULTS

The outbreak of the Second World War shifted research at the interdisciplinary HFL toward the field of military physiology and resulted in the transfer of Brouha from Belgium to the HFL. Brouha's personal and academic experiences made him the right man in the right place to develop the HST in 1942. The HST--which has celebrated its 70th anniversary--was of immediate academic and practical significance during and after the war.

CONCLUSIONS

Brouha' s case demonstrates the importance of personal experiences, transnational relations, and interdisciplinary research settings for the establishment of scientific (sub)disciplines. Studying internal scientific evolutions in relation to personal and work experiences of "mobile" and therefore often "forgotten" researchers like Brouha is necessary to better understand and interpret evolutions in science and corresponding processes of academic and social mobility.

Effect of a prolonged altitude expedition on glucose tolerance and abdominal fatness

In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO2) was substantially reduced during hiking. Glucose tolerance and insulin responses were measured prior to and twice during the expedition period. Maximal oxygen consumption increased from 43.0 +/- 2.7 to 49.1 +/- 2.2 mL/kg/min. Percentage of body fat decreased from 19.4 +/- 6.8% to 16.9 +/- 5.9%. The area under the curves for insulin and glucose during the oral glucose tolerance test were also reduced in Days 3 and 25. The present study demonstrated that altitude hiking activity is an effective lifestyle intervention to improve insulin action.