scholarly journals Aerobic Capacity, Lactate Concentration, and Work Assessment During Maximum Exercise at Sea Level and High Altitude in Miners Exposed to Chronic Intermittent Hypobaric Hypoxia (3,800 m)

2019 ◽  
Vol 10 ◽  
Author(s):  
Fernando A. Moraga ◽  
Jorge Osorio ◽  
Daniel Jiménez ◽  
Rodrigo Calderón-Jofré ◽  
Daniel Moraga
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Aerobic Capacity ◽  
Hypobaric Hypoxia ◽  
Lactate Concentration ◽  
Maximum Exercise ◽  
Intermittent Hypobaric Hypoxia ◽  
Work Assessment

The effect of intermittent hypobaric hypoxic exposure and sea level training on submaximal economy in well-trained swimmers and runners

2008 ◽  
Vol 104 (2) ◽  
pp. 328-337 ◽  
Author(s):  
Martin J. Truijens ◽  
Ferran A. Rodríguez ◽  
Nathan E. Townsend ◽  
James Stray-Gundersen ◽  
Christopher J. Gore ◽  
...  
Keyword(s):  
Sea Level ◽  
Repeated Measures ◽  
Hypobaric Hypoxia ◽  
Lactate Concentration ◽  
Hypoxic Exposure ◽  
Double Blind ◽  
Intermittent Hypobaric Hypoxia ◽  
Post Test ◽  
Double Blind Design ◽  
Level Training

To evaluate the effect of intermittent hypobaric hypoxia combined with sea level training on exercise economy, 23 well-trained athletes (13 swimmers, 10 runners) were assigned to either hypobaric hypoxia (simulated altitude of 4,000–5,500 m) or normobaric normoxia (0–500 m) in a randomized, double-blind design. Both groups rested in a hypobaric chamber 3 h/day, 5 days/wk for 4 wk. Submaximal economy was measured twice before (Pre) and after (Post) the treatment period using sport-specific protocols. Economy was estimated both from the relationship between oxygen uptake (V̇o2) and speed, and from the absolute V̇o2 at each speed using sport-specific protocols. V̇o2 was measured during the last 60 s of each (3–4 min) stage using Douglas bags. Ventilation (V̇e), heart rate (HR), and capillary lactate concentration ([La−]) were measured during each stage. Velocity at maximal V̇o2 (velocity at v̇o2max) was used as a functional indicator of changes in economy. The average V̇o2 for a given speed of the Pre values was used for Post test comparison using a two-way, repeated-measures ANOVA. Typical error of measurement of V̇o2 was 4.7% (95% confidence limits 3.6–7.1), 3.6% (2.8–5.4), and 4.2% (3.2–6.9) for speeds 1, 2, and 3, respectively. There was no change in economy within or between groups (ANOVA interaction P = 0.28, P = 0.23, and P = 0.93 for speeds 1, 2, and 3). No differences in submaximal HR, [La−], V̇e, or velocity at V̇o2max were found between groups. It is concluded that 4 wk of intermittent hypobaric hypoxia did not improve submaximal economy in this group of well-trained athletes.

scholarly journals Cardiovascular Risk Is Increased in Miner’s Chronic Intermittent Hypobaric Hypoxia Exposure From 0 to 2,500 m?

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrés Pedreros-Lobos ◽  
Rodrigo Calderón-Jofré ◽  
Daniel Moraga ◽  
Fernando A. Moraga
Keyword(s):  
Sea Level ◽  
Aerobic Capacity ◽  
Hypobaric Hypoxia ◽  
Venous Blood ◽  
Overweight And Obesity ◽  
Experimental Population ◽  
Moderate Altitude ◽  
Intermittent Hypobaric Hypoxia ◽  
Increased Risk ◽  
Significant Difference

Over the past 40 years, mining activities in Chile have relocated miners who normally live at sea level to work at high altitudes. This results in a form of chronic intermittent hypobaric hypoxia (CIHH) characterized by alternating periods of work at high altitude and rest periods at sea level. Previous studies performed in our laboratory showed that aerobic capacity is reduced at 3,800 m, even when oxygen content is maintained. Our study aimed to determine the corporal composition, food intake, maximum oxygen uptake, and concentration of high sensitivity C reactive protein (hsCRP) in an acclimatized miner population that work from 0 to 2,500 m with CIHH exposure over 4 years. All miners recruited for our study were operators of heavy trucks with CIHH for over 4 years (shiftwork 7*7 days), and our experimental population was composed of 54 miners at sea level, 61 at 1,600 m, and 38 at 2,500 m. All evaluations were performed on the 3rd or 4th day of diurnal shiftwork. To determine corporal composition, we measured weight and height (to calculate body mass index, BMI), skinfolds (to calculate body fatty, BF), and waist circumference (WC); maximal aerobic capacity was evaluated using a ramp-incremental cycling to exhaustion protocol and a venous blood sample before the exercise test to measure (hsCRP) via an ELISA test. We found higher values of BMI, BF, and WC, in the miners’ population but observed no significant difference between populations. We found a decrease in VO2 of 11.6% at 1,600 m and 25.9% at 2,500 m compared to miners at sea level. An increase in (hsCRP) at 1,600 and 2,500 m regards sea level. We observed a high prevalence of overweight and obese subjects, which was related to the ad libitum availability of food and low physical activity (sedentarism). We found that work capacity was maintained despite a decreased VO2 max at moderate altitude. However, overweight and obesity support an increased risk of cardiometabolic disease in miner’s which is unrelated to altitude. In contrast, an increased hsCRP level could be associated with increased inflammatory mechanisms at 1,600 and 2,500 m.

scholarly journals Adenosine receptor-dependent signaling is not obligatory for normobaric and hypobaric hypoxia-induced cerebral vasodilation in humans

2017 ◽  
Vol 122 (4) ◽  
pp. 795-808 ◽  
Author(s):  
Ryan L. Hoiland ◽  
Anthony R. Bain ◽  
Michael M. Tymko ◽  
Mathew G. Rieger ◽  
Connor A. Howe ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
High Altitude ◽  
Sea Level ◽  
Adenosine Receptor ◽  
Hypobaric Hypoxia ◽  
End Tidal ◽  
Double Blinded

Hypoxia increases cerebral blood flow (CBF) with the underlying signaling processes potentially including adenosine. A randomized, double-blinded, and placebo-controlled design, was implemented to determine if adenosine receptor antagonism (theophylline, 3.75 mg/Kg) would reduce the CBF response to normobaric and hypobaric hypoxia. In 12 participants the partial pressures of end-tidal oxygen ([Formula: see text]) and carbon dioxide ([Formula: see text]), ventilation (pneumotachography), blood pressure (finger photoplethysmography), heart rate (electrocardiogram), CBF (duplex ultrasound), and intracranial blood velocities (transcranial Doppler ultrasound) were measured during 5-min stages of isocapnic hypoxia at sea level (98, 90, 80, and 70% [Formula: see text]). Ventilation, [Formula: see text] and [Formula: see text], blood pressure, heart rate, and CBF were also measured upon exposure (128 ± 31 min following arrival) to high altitude (3,800 m) and 6 h following theophylline administration. At sea level, although the CBF response to hypoxia was unaltered pre- and postplacebo, it was reduced following theophylline ( P < 0.01), a finding explained by a lower [Formula: see text] ( P < 0.01). Upon mathematical correction for [Formula: see text], the CBF response to hypoxia was unaltered following theophylline. Cerebrovascular reactivity to hypoxia (i.e., response slope) was not different between trials, irrespective of [Formula: see text]. At high altitude, theophylline ( n = 6) had no effect on CBF compared with placebo ( n = 6) when end-tidal gases were comparable ( P > 0.05). We conclude that adenosine receptor-dependent signaling is not obligatory for cerebral hypoxic vasodilation in humans. NEW & NOTEWORTHY The signaling pathways that regulate human cerebral blood flow in hypoxia remain poorly understood. Using a randomized, double-blinded, and placebo-controlled study design, we determined that adenosine receptor-dependent signaling is not obligatory for the regulation of human cerebral blood flow at sea level; these findings also extend to high altitude.

Effects of Four Weeks of Intermittent Hypobaric Hypoxia on Sea Level Running and Swimming Performance

2004 ◽  
Vol 36 (Supplement) ◽  
pp. S338 ◽  
Author(s):  
Fernando A. Rodriguez ◽  
Martin J. Truijens ◽  
Nathan E. Townsend ◽  
Emily R. Martini ◽  
James Stray-Gundersen ◽  
...  
Keyword(s):  
Sea Level ◽  
Hypobaric Hypoxia ◽  
Swimming Performance ◽  
Intermittent Hypobaric Hypoxia ◽  
Level Running

Intermittent hypobaric hypoxia stimulates erythropoiesis and improves aerobic capacity

1999 ◽  
Vol 31 (2) ◽  
pp. 264-268 ◽  
Author(s):  
FERRAN A. RODR??GUEZ ◽  
H??CTOR CASAS ◽  
MIREIA CASAS ◽  
TERESA PAG??S ◽  
RAM??N RAMA ◽  
...  
Keyword(s):  
Aerobic Capacity ◽  
Hypobaric Hypoxia ◽  
Intermittent Hypobaric Hypoxia

Modulation of the contractile responses of guinea pig isolated tracheal rings after chronic intermittent hypobaric hypoxia with and without cold exposure

2005 ◽  
Vol 99 (3) ◽  
pp. 1006-1011 ◽  
Author(s):  
Kaveri Chakrabarty ◽  
M. Fahim
Keyword(s):  
Smooth Muscle ◽  
High Altitude ◽  
Cold Exposure ◽  
Hypobaric Hypoxia ◽  
Intermittent Hypoxia ◽  
Contractile Response ◽  
Tracheal Smooth Muscle ◽  
Contractile Responses ◽  
Intermittent Hypobaric Hypoxia ◽  
The Impact

Previous studies have documented that repetitive exposure to intermittent hypoxia, such as that encountered in preparation to high-altitude ascent, influences breathing. However, the impact of intermittent hypoxia on airway smooth muscle has not been explored. Ascents to high altitude, in addition to hypoxia, expose individuals to cold air. The objective of the present study is to examine the effect of chronic intermittent hypobaric hypoxia (CIH) and CIH combined with cold exposure (CIHC) on tracheal smooth muscle responses to various contractile and relaxant agonists. Experiments were performed on tracheal rings harvested from adult guinea pigs exposed either to CIH or CIHC [14 days (6 h/day) at barometric pressure of 350 mmHg with and without cold exposure of 5°C] or to room air (normoxia). CIH and CIHC attenuated maximum contractile responses to ACh compared with normoxia. The maximum contractile response to histamine decreased with CIH, whereas CIHC restored the response back to normoxia. Both CIH and CIHC attenuated maximum contractile responses to 5-HT. Altered contractile responses after CIH and CIHC were independent of epithelium. Isoproterenol-induced relaxation was not altered by CIH, whereas it was enhanced after CIHC, and these responses were independent of the epithelium. The data demonstrate that intermittent exposure to hypoxia profoundly influences contractile response of tracheal smooth muscle, and cold exposure can further modulate the response, implying the importance of cold at high altitude.

Beta-adrenergic blockade does not prevent the lactate response to exercise after acclimatization to high altitude

1994 ◽  
Vol 76 (2) ◽  
pp. 610-615 ◽  
Author(s):  
R. S. Mazzeo ◽  
G. A. Brooks ◽  
G. E. Butterfield ◽  
A. Cymerman ◽  
A. C. Roberts ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Blood Lactate ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Control Group ◽  
Adrenergic Blockade ◽  
Arterial O2 Saturation ◽  
Response To Exercise ◽  
Peak Blood

We examined the extent to which epinephrine influences blood lactate adjustments to exercise during both acute (AC) and chronic (CH) high-altitude exposure. Eleven male sea level residents were divided into a control group (n = 5) receiving a placebo or a drug group (n = 6) receiving 240 mg/day of propranolol. All subjects were studied at rest and during 45 min of submaximal exercise (approximately 50% of sea level maximal O2 uptake) at sea level (SL) and within 4 h of exposure to and after 3 wk residence at 4,300 m (summit of Pikes Peak). Blood samples were collected from the femoral artery for epinephrine and lactate concentration. Exercising blood lactate concentration was significantly different across all altitude conditions such that AC > CH > SL (P < 0.05). For a given arterial O2 saturation, mean exercising blood lactates were lower for the beta-blocked group compared with controls; however, both groups demonstrated similar patterns across all conditions. Epinephrine levels during exercise followed a similar pattern to that of lactate, averaging 0.67, 0.43, and 0.29 ng/ml for AC, CH, and SL, respectively. The correlation between lactate and epinephrine was 0.93 and 0.84 for control and beta-blocked subjects, respectively. Whereas during exercise epinephrine was consistently higher for the beta-blocked group than controls, this difference was only significant during CH exposure. The epinephrine response was related to the extent of hypoxia in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased reliance on lactate during exercise after acclimatization to 4,300 m

1991 ◽  
Vol 71 (1) ◽  
pp. 333-341 ◽  
Author(s):  
G. A. Brooks ◽  
G. E. Butterfield ◽  
R. R. Wolfe ◽  
B. M. Groves ◽  
R. S. Mazzeo ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Blood Lactate ◽  
Lactate Concentration ◽  
Acute Exposure ◽  
O2 Consumption ◽  
Arterial Lactate ◽  
Healthy Men ◽  
Subsequent Decrease ◽  
Appearance Rate

We hypothesized that the increased exercise arterial lactate concentration on arrival at high altitude and the subsequent decrease with acclimatization were caused by changes in blood lactate flux. Seven healthy men [age 23 +/- 2 (SE) yr, wt 72.2 +/- 1.6 kg] on a controlled diet were studied in the postabsorptive condition at sea level, on acute exposure to 4,300 m, and after 3 wk of acclimatization to 4,300 m. Subjects received a primed-continuous infusion of [6,6–2D]glucose (Brooks et al. J. Appl. Physiol. 70:919–927, 1991) and [3–13C]lactate and rested for a minimum of 90 min followed immediately by 45 min of exercise at 101 +/- 3 W, which elicited 51.1 +/- 1% of the sea level peak O2 consumption (VO2peak; 65 +/- 2% of both acute altitude and acclimatization). During rest at sea level, lactate appearance rate (Ra) was 0.52 +/- 0.03 mg.kg-1.min-1; this increased sixfold during exercise to 3.24 +/- 0.19 mg.kg-1.min-1. On acute exposure, resting lactate Ra rose from sea level values to 2.2 +/- 0.2 mg.kg-1.min-1. During exercise on acute exposure, lactate Ra rose to 18.6 +/- 2.9 mg.kg-1.min-1. Resting lactate Ra after acclimatization (1.77 +/- 0.25 mg.kg-1.min-1) was intermediate between sea level and acute exposure values. During exercise after acclimatization, lactate Ra (9.2 +/- 0.7 mg.kg-1.min-1) rose from resting values but was intermediate between sea level and acute exposure values. The increased exercise arterial lactate concentration response on arrival at high altitude and subsequent decrease with acclimatization are due to changes in blood lactate appearance.(ABSTRACT TRUNCATED AT 250 WORDS)

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