Work capacity in chronic exposures to altitude.

Dill, D. B.; Myhre, L. G.; Brown, Darine F.; Burrus, K; Gehlsen, Gale M.

doi:10.1152/jappl.1967.23.4.555

Cited by 19 publications

(10 citation statements)

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“…Our finding that the lactate paradox persists over 8 weeks at 3800 m disagrees with the recent studies by van Hall and Lundby but is consistent with the work of previous authors (Dill et al, 1967;Hansen et al, 1967;West et al, 1983;Bender et al, 1989;Brooks et al, 1991;Brooks et al, 1992;Beidleman et al, 1997;Brooks et al, 1998). However, since other studies only collected data for a shorter period at altitude (2 to 5 weeks), without control for different altitude levels and workloads during acclimatization, it was possible that they may not have detected reversal of the LP.…”

Section: Other Comparisons With the Literaturesupporting

confidence: 84%

“…P REVIOUS STUDIES HAVE SHOW N that the relationship between arterial lactate concentration and workload during exercise is elevated in acute hypoxia (H), but then falls, returning to near the sea level (SL) relationship after about 2 weeks at altitude (Edwards, 1936;Dill et al, 1967;Hansen et al, 1967;Cerretelli, 1980;West et al, 1983;Kayser et al, 1993;Bender et al, 1989;Beidleman et al, 1997). This, together with a reduction in lactate levels at exhaustion, is known as the lactate paradox (West, 1986).…”

Section: Introductionmentioning

confidence: 99%

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Persistence of the Lactate Paradox over 8 Weeks at 3800 m

Pronk

Tiemessen²,

Hupperets³

et al. 2003

High Altitude Medicine & Biology

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The arterial blood lactate [La] response to exercise increases in acute hypoxia, but returns to near the normoxic (sea level, SL) response after 2 to 5 weeks of altitude acclimatization. Recently, it has been suggested that this gradual return to the SL response in [La], known as the lactate paradox (LP), unexpectedly disappears after 8 to 9 weeks at altitude. We tested this idea by recording the [La] response to exercise every 2 weeks over 8 weeks at altitude. Five normal, fit SL-residents were studied at SL and 3,800 m (Pbar = 485 torr) in both normoxia (PIO2 = 150 torr) and hypoxia (PIO2 = 91 torr approximately air at 3,800 m). Arterial [La] and blood gas values were determined at rest and during cycle exercise at the same absolute workloads (0, 25, 50, 75, 90, and 100% of initial SL-VO2Max) and exercise duration (4, 4, 4, 2, 1.5, and 0.75 min, respectively) at each time point. [La] curves were elevated in acute hypoxia at SL (p < 0.01) and at 3,800 m fell progressively toward the SL-normoxic curve (p < 0.01). On the same days, [La] responses in acute normoxia showed essentially no changes over time and were similar to initial SL normoxic responses. We also measured arterial catecholamine levels at each load and found a close relationship to [La] over time, supporting a role for adrenergic influence on [La]. In summary, extending the time at this altitude to 8 weeks produced no evidence for reversal of the LP, consistent with prior data obtained over shorter periods of altitude residence.

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Section: Other Comparisons With the Literaturesupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Persistence of the Lactate Paradox over 8 Weeks at 3800 m

Pronk

Tiemessen²,

Hupperets³

et al. 2003

High Altitude Medicine & Biology

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“…The earliest observations of this phenomenon were made in the 1930s ( Dill et al . 1931 , Edwards 1936) with many subsequent confirming reports ( Cerretelli 1967, 1980, Dill et al . 1967 , Hansen et al .…”

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confidence: 75%

The ‘lactate paradox’, evidence for a transient change in the course of acclimatization to severe hypoxia in lowlanders

Lundby

Saltin

Hall

2000

Acta Physiologica Scandinavica

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The metabolic response to exercise at high altitude is different from that at sea level, depending on the altitude, the rate of ascent and duration of acclimatization. One apparent metabolic difference that was described in the 1930s is the phenomenon referred to as the 'lactate paradox'. Acute exposure to hypoxia results in higher blood lactate accumulation at submaximal workloads compared with sea level, but peak blood lactate remain the same. Following continued exposure to hypoxia or altitude, blood lactate accumulation at submaximal work and peak blood lactate levels are paradoxically reduced compared with those at sea level. It has recently been shown, however, that, if the exposure to altitude is sufficiently long, blood lactate responses return to those seen at sea level or during acute hypoxia. Thus, to evaluate the 'lactate paradox' phenomenon in relation to time spent at altitude, five Danish lowland climbers were studied at sea level, during acute exposure to hypoxia (10% O2 in N2) and 1, 4 and 6 weeks after arrival in the basecamp of Mt Everest (approximately 5400 m, Nepal). Basecamp was reached after 10 days of gradual ascent from 2800 m. Peak blood lactate levels were similar at sea level (11.0 +/- 0.7 mmol L-1) and during acute hypoxia (9.9 +/- 0.3 mmol L-1), but fell significantly after 1 week of acclimatization to 5400 m (5.6 +/- 0.5 mmol L-1) as predicted by the 'lactate paradox'. After 4 weeks of acclimatization, peak lactate accumulation (7.8 +/- 1.0 mmol L-1) was still lower compared with acute hypoxia but higher than that seen after 1 week of acclimatization. After 6 weeks of acclimatization, 2 days after return to basecamp after reaching the summit or south summit of Mt Everest, peak lactate levels (10.4 +/- 1.1 mmol L-1) were similar to those seen during acute hypoxia. Therefore, these results suggest that the 'lactate paradox' is a transient metabolic phenomenon that is reversed during a prolonged period of exposure to severe hypoxia of more than 6 weeks.

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“…This detrimental effect of arterial hypoxemia on aerobic capacity is exacerbated during exercise in hypoxia (Kayser et al, 1994;Amann and Calbet, 2008). As Amann and Kayser (2009) noted, this impairment of aerobic capacity, during both acute and chronic exposure to high altitude, has been well documented in both moderately and highly trained individuals (Dill et al, 1966(Dill et al, , 1967Klausen et al, 1966;Maher et al, 1974;Calbet et al, 2003;Lundby et al, 2004Lundby et al, , 2006. Furthermore, it appears that people with higher aerobic fitness at sea level are more adversely affected in hypoxia (Martin and O'Kroy, 1993;Gore et al, 1996;Ferretti et al, 1997;Mollard et al, 2007;Calbet and Lundby, 2009), due to greater reductions in SaO 2 , CaO 2 , and therefore mass O 2 transport (Ekblom et al, 1975;Chapman et al, 1999;Calbet and Lundby, 2009).…”

Section: Introductionmentioning

confidence: 97%

Fatigue and Exhaustion in Hypoxia: The Role of Cerebral Oxygenation

Fan

Kayser

2016

High Altitude Medicine & Biology

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Fan, Jui-Lin, and Bengt Kayser. Fatigue and exhaustion in hypoxia: the role of cerebral oxygenation. High Alt Med Biol. 17:72-84, 2016.-It is well established that ascent to high altitude is detrimental to one's aerobic capacity and exercise performance. However, despite more than a century of research on the effects of hypoxia on exercise performance, the underlying mechanisms remain incompletely understood. While the cessation of exercise, or the reduction of its intensity, at exhaustion, implies reduced motor recruitment by the central nervous system, the mechanisms leading up to this muscular derecruitment remain elusive. During exercise in normoxia and moderate hypoxia (∼1500-2500 m), peripheral fatigue and activation of muscle afferents probably play a major role in limiting exercise performance. Meanwhile, studies suggested that cerebral tissue deoxygenation may play a pivotal role in impairing aerobic capacity during exercise in more severe hypoxic conditions (∼4500-6000 m). However, recent studies using end-tidal CO2 clamping, to improve cerebral tissue oxygenation during exercise in hypoxia, failed to demonstrate an improvement in exercise performance. In light of these recent findings, which seem to contradict the hypothetical role of cerebral tissue deoxygenation as a performance limiting factor at high altitude, this short review aims to provide a critical reappraisal of the extant literature and ends exploring some potential avenues for further research in this field.

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Work capacity in chronic exposures to altitude.

Cited by 19 publications

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Persistence of the Lactate Paradox over 8 Weeks at 3800 m

Persistence of the Lactate Paradox over 8 Weeks at 3800 m

The ‘lactate paradox’, evidence for a transient change in the course of acclimatization to severe hypoxia in lowlanders

Fatigue and Exhaustion in Hypoxia: The Role of Cerebral Oxygenation

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