Physical exercise, acid-base balance, and adrenal function in newcomers to high altitude.

Moncloa, F; Carcelén, Amador; Beteta, Luis

doi:10.1152/jappl.1970.28.2.151

Cited by 8 publications

(17 citation statements)

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“…Subsequent renal compensation of the acute respiratory alkalosis induces a reduction in blood bicarbonate ([HCO 3 − ]) concentrations, and the resulting decline in the blood buffering capacity during altitude adaption has been suggested to have a significant effect on exercise performance at altitude, particularly above the lactate threshold [6][7][8][9]. These findings are supported by the fact that exerciseinduced acidosis is more severe at altitude compared with sea level [6,10].…”

Section: Introductionmentioning

confidence: 99%

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

Limmer

Marées

Platen

2020

Journal of the International Society of Sports Nutrition

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Background: The present study investigated the effects of chronic sodium bicarbonate (NaHCO 3 ) ingestion on a single bout of high-intensity exercise and on acid-base balance during 7-day high-altitude exposure. Methods: Ten recreationally active subjects participated in a pre-test at sea level and a 7-day hiking tour in the Swiss Alps up to 4554 m above sea level. Subjects received either a daily dose of 0.3 g/kg NaHCO 3 solution (n = 5) or water as a placebo (n = 5) for 7 days. Anaerobic high-intensity exercise performance was assessed using the portable tethered sprint running (PTSR) test under normoxic and hypoxic conditions (3585 m). PTSR tests assessed overall peak force, mean force, and fatigue index. Blood lactate levels and blood gas parameters were assessed preand post-PTSR. Urinary pH and blood gas parameters were further analyzed daily at rest in early morning samples under normoxic and hypoxic conditions. Results: There were no significant differences between the bicarbonate and control group in any of the PTSRrelated parameters. However, urinary pH (p = 0.003, ηp 2 = 0.458), early morning blood bicarbonate concentration (p < 0.001, ηp 2 = 0.457) and base excess (p = 0.002, ηp 2 = 0.436) were significantly higher in the bicarbonate group compared with the control group under hypoxic conditions. (Continued on next page)Conclusions: These results indicate that oral NaHCO 3 ingestion does not ameliorate the hypoxia-induced impairment in anaerobic, high-intensity exercise performance, represented by PTSR-related test parameters, under hypobaric, hypoxic conditions, but the maximal performance measurements may have been negatively affected by other factors, such as poor implementation of PTSR test instructions, pre-acclimatization, the time course of hypoxia-induced renal [HCO 3 − ] compensation, changes in the concentrations of intra-and extracellular ions others than [H + ] and [HCO 3 − ], or gastrointestinal disturbances caused by NaHCO 3 ingestion. However, chronic NaHCO 3 ingestion improves blood bicarbonate concentration and base excess at altitude, which partially represent the blood buffering capacity.

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Section: Introductionmentioning

confidence: 99%

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

Limmer

Marées

Platen

2020

Journal of the International Society of Sports Nutrition

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“…Overall, 56 original articles reporting data on ABGs under hypobaric hypoxic conditions among healthy volunteers met inclusion criteria. A Galbraith plot including those 56 studies identified 3 visual outliers, which were excluded (eResults and eFigure 1 in Supplement 1).…”

Section: Resultsmentioning

confidence: 99%

“…In total, 53 studies reporting 115 group ascents to altitudes between 1524 m and 8730 m were included in the aggregated data analysis. Two of those studies (3.8%) were not incorporated into the forest plot due to missing measurements of variance.…”

Section: Resultsmentioning

confidence: 99%

“…For 13 of those studies (24.5%) reporting 29 ascents, the IPD were retrieved and included in IPD analyses. All of the included studies were published between 1967 and 2022; characteristics of all included studies are shown in eTable 1 in Supplement 1. The funnel plot revealed an even distribution around the mean effect size; no reporting bias was detected (eFigure 2 in Supplement 1).…”

Section: Resultsmentioning

confidence: 99%

“…The association of altitude (standardized for 1000 m vertical gain) with Pa o 2 is shown in the forest plot in Figure 2. The mean point estimate calculated for the 51 included studies was a reduction of 1.60 kPa in Pa o 2 per kilometer of vertical ascent. The 95% CI of the overall effect estimate was 1.47 to 1.73 kPa.…”

Section: Resultsmentioning

confidence: 99%

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Partial Pressure of Arterial Oxygen in Healthy Adults at High Altitudes

Forrer,

Gaisl,

Sevik

et al. 2023

JAMA Netw Open

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ImportanceWith increasing altitude, the partial pressure of inspired oxygen decreases and, consequently, the Pao2 decreases. Even though this phenomenon is well known, the extent of the reduction as a function of altitude remains unknown.ObjectiveTo calculate an effect size estimate for the decrease in Pao2 with each kilometer of vertical gain among healthy unacclimatized adults and to identify factors associated with Pao2 at high altitude (HA).Data SourcesA systematic search of PubMed and Embase was performed from database inception to April 11, 2023. Search terms included arterial blood gases and altitude.Study SelectionA total of 53 peer-reviewed prospective studies in healthy adults providing results of arterial blood gas analysis at low altitude (&lt;1500 m) and within the first 3 days at the target altitude (≥1500 m) were analyzed.Data Extraction and SynthesisPrimary and secondary outcomes as well as study characteristics were extracted from the included studies, and individual participant data (IPD) were requested. Estimates were pooled using a random-effects DerSimonian-Laird model for the meta-analysis.Main Outcomes and MeasuresMean effect size estimates and 95% CIs for reduction in Pao2 at HA and factors associated with Pao2 at HA in healthy adults.ResultsAll of the 53 studies involving 777 adults (mean [SD] age, 36.2 [10.5] years; 510 men [65.6%]) reporting 115 group ascents to altitudes between 1524 m and 8730 m were included in the aggregated data analysis; 13 of those studies involving 305 individuals (mean [SD] age, 39.8 [13.6] years; 185 men [60.7%]) reporting 29 ascents were included in the IPD analysis. The estimated effect size of Pao2 was −1.60 kPa (95% CI, −1.73 to −1.47 kPa) for each 1000 m of altitude gain (τ2 = 0.14; I2 = 86%). The Pao2 estimation model based on IPD data revealed that target altitude (−1.53 kPa per 1000 m; 95% CI, −1.63 to −1.42 kPa per 1000 m), age (−0.01 kPa per year; 95% CI, −0.02 to −0.003 kPa per year), and time spent at an altitude of 1500 m or higher (0.16 kPa per day; 95% CI, 0.11-0.21 kPa per day) were significantly associated with Pao2.Conclusions and RelevanceIn this systematic review and meta-analysis, the mean decrease in Pao2 was 1.60 kPa per 1000 m of vertical ascent. This effect size estimate may improve the understanding of physiological mechanisms, assist in the clinical interpretation of acute altitude illness in healthy individuals, and serve as a reference for physicians counseling patients with cardiorespiratory disease who are traveling to HA regions.

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Endocrine Adaptation to Hypoxia

Raff

1996

Comprehensive Physiology

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Physical exercise, acid-base balance, and adrenal function in newcomers to high altitude.

Cited by 8 publications

References 0 publications

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

Partial Pressure of Arterial Oxygen in Healthy Adults at High Altitudes

Endocrine Adaptation to Hypoxia

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