scholarly journals Acute Exposure to Normobaric Hypoxia Impairs Balance Performance in Sub-elite but Not Elite Basketball Players

2021 ◽  
Vol 12 ◽  
Author(s):  
Haris Pojskić ◽  
Helen G. Hanstock ◽  
Tsz-Hin Tang ◽  
Lara Rodríguez-Zamora
Keyword(s):  
Sea Level ◽  
Normobaric Hypoxia ◽  
Acute Exposure ◽  
Hypoxic Exposure ◽  
Altitude Training ◽  
Balance Performance ◽  
Basketball Players ◽  
Peripheral Oxygen Saturation ◽  
Elite Group ◽  
Over Time

Although high and simulated altitude training has become an increasingly popular training method, no study has investigated the influence of acute hypoxic exposure on balance in team-sport athletes. Therefore, the purpose of this study was to investigate whether acute exposure to normobaric hypoxia is detrimental to balance performance in highly-trained basketball players. Nine elite and nine sub-elite male basketball players participated in a randomized, single-blinded, cross-over study. Subjects performed repeated trials of a single-leg balance test (SLBT) in an altitude chamber in normoxia (NOR; approximately sea level) with FiO2 20.9% and PiO2 ranging from 146.7 to 150.4 mmHg and in normobaric hypoxia (HYP; ~3,800 m above sea level) with FiO2 13.0% and PiO2 ranging from 90.9 to 94.6 mmHg. The SLBT was performed three times: 15 min after entering the environmental chamber in NOR or HYP, then two times more interspersed by 3-min rest. Peripheral oxygen saturation (SpO2) and heart rate (HR) were recorded at four time points: after the initial 15-min rest inside the chamber and immediately after each SLBT. Across the cohort, the balance performance was 7.1% better during NOR than HYP (P < 0.01, ηp2 = 0.58). However, the performance of the elite group was not impaired by HYP, whereas the sub-elite group performed worse in the HYP condition on both legs (DL: P = 0.02, d = 1.23; NDL: P = 0.01, d = 1.43). SpO2 was lower in HYP than NOR (P < 0.001, ηp2 = 0.99) with a significant decline over time during HYP. HR was higher in HYP than NOR (P = 0.04, ηp2 = 0.25) with a significant increase over time. Acute exposure to normobaric hypoxia detrimentally affected the balance performance in sub-elite but not elite basketball players.

Live High + Train Low: Thinking in Terms of an Optimal Hypoxic Dose

2007 ◽  
Vol 2 (3) ◽  
pp. 223-238 ◽  
Author(s):  
Randall L. Wilber
Keyword(s):  
Sea Level ◽  
Physiological Responses ◽  
Hypoxic Exposure ◽  
Altitude Training ◽  
Subsequent Increase ◽  
Endogenous Erythropoietin ◽  
Altitude Acclimatization ◽  
Performance Effects ◽  
Key Issues ◽  
Level Performance

“Live high-train low” (LH+TL) altitude training allows athletes to “live high” for the purpose of facilitating altitude acclimatization, as characterized by a significant and sustained increase in endogenous erythropoietin and subsequent increase in erythrocyte volume, while simultaneously enabling them to “train low” for the purpose of replicating sea-level training intensity and oxygen flux, thereby inducing beneficial metabolic and neuromuscular adaptations. In addition to natural/terrestrial LH+TL, several simulated LH+TL devices have been developed including nitrogen apartments, hypoxic tents, and hypoxicator devices. One of the key issues regarding the practical application of LH+TL is what the optimal hypoxic dose is that is needed to facilitate altitude acclimatization and produce the expected beneficial physiological responses and sea-level performance effects. The purpose of this review is to examine this issue from a research-based and applied perspective by addressing the following questions: What is the optimal altitude at which to live, how many days are required at altitude, and how many hours per day are required? It appears that for athletes to derive the hematological benefits of LH+TL while using natural/terrestrial altitude, they need to live at an elevation of 2000 to 2500 m for >4 wk for >22 h/d. For athletes using LH+TL in a simulated altitude environment, fewer hours (12-16 h) of hypoxic exposure might be necessary, but a higher elevation (2500 to 3000 m) is required to achieve similar physiological responses.

scholarly journals A Holistic Framework for Evaluating Adaptation Approaches to Coastal Hazards and Sea Level Rise: A Case Study from Imperial Beach, California

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1324
Author(s):  
David Revell ◽  
Phil King ◽  
Jeff Giliam ◽  
Juliano Calil ◽  
Sarah Jenkins ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Public Trust ◽  
Adaptation Strategy ◽  
Public Benefits ◽  
Study Results ◽  
Local Risk ◽  
Over Time

Sea level rise increases community risks from erosion, wave flooding, and tides. Current management typically protects existing development and infrastructure with coastal armoring. These practices ignore long-term impacts to public trust coastal recreation and natural ecosystems. This adaptation framework models physical responses to the public beach and private upland for each adaptation strategy over time, linking physical changes in widths to damages, economic costs, and benefits from beach recreation and nature using low-lying Imperial Beach, California, as a case study. Available coastal hazard models identified community vulnerabilities, and local risk communication engagement prioritized five adaptation approaches—armoring, nourishment, living shorelines, groins, and managed retreat. This framework innovates using replacement cost as a proxy for ecosystem services normally not valued and examines a managed retreat policy approach using a public buyout and rent-back option. Specific methods and economic values used in the analysis need more research and innovation, but the framework provides a scalable methodology to guide coastal adaptation planning everywhere. Case study results suggest that coastal armoring provides the least public benefits over time. Living shoreline approaches show greater public benefits, while managed retreat, implemented sooner, provides the best long-term adaptation strategy to protect community identity and public trust resources.

Altitude Training in Elite Swimmers for Sea Level Performance (Altitude Project)

2015 ◽  
Vol 47 (9) ◽  
pp. 1965-1978 ◽  
Author(s):  
FERRAN A. RODRÍGUEZ ◽  
XAVIER IGLESIAS ◽  
BELÉN FERICHE ◽  
CARMEN CALDERÓN-SOTO ◽  
DIEGO CHAVERRI ◽  
...  
Keyword(s):  
Sea Level ◽  
Altitude Training ◽  
Elite Swimmers ◽  
Level Performance

A STUDY OF VARIOUS INDICES OF ADRENOCORTICAL ACTIVITY DURING 23 DAYS AT HIGH ALTITUDE

1963 ◽  
Vol 26 (4) ◽  
pp. 555-566 ◽  
Author(s):  
P. C. B. MACKINNON ◽  
M. E. MONK-JONES ◽  
K. FOTHERBY
Keyword(s):  
Length Of Stay ◽  
High Altitude ◽  
Sea Level ◽  
Acute Exposure ◽  
Adrenocorticotrophic Hormone ◽  
Adrenocortical Activity

SUMMARY 1. Four men and three women ascended by télépherique and helicopter from 1000 to 4333 m. where they remained for 23 days. 2. Measurements of urinary 17-hydroxycorticosteroids, 17-oxosteroids, pregnanediol and pregnanetriol and circulating eosinophils were made at sea level and at high altitude. 3. An attempt was also made to measure changes in emotional activity by means of the palmar sweat index (PSI). This index was assessed at intervals throughout the day at sea level and at high altitude, and in response to adrenocorticotrophic hormone (ACTH) and a self-imposed stress. 4. Within 24 hr. of acute exposure to high altitude urinary 17-hydroxycorticosteroids increased whilst circulating eosinophils decreased; by the 5th day both were returning to sea-level values. The output of 17-oxosteroids was lower by the 5th day at high altitude and subsequently increased; pregnanediol and pregnanetriol levels remained unchanged. 5. PSIs throughout the day become progressively lower as the length of stay at altitude increased. The response to ACTH at sea level and high altitude appeared to be similar but the response to a self-imposed stress was longer in duration at high altitude than at sea level.

Individual variation in response to altitude training

1998 ◽  
Vol 85 (4) ◽  
pp. 1448-1456 ◽  
Author(s):  
Robert F. Chapman ◽  
James Stray-Gundersen ◽  
Benjamin D. Levine
Keyword(s):  
Cell Volume ◽  
Sea Level ◽  
Interval Training ◽  
Training Model ◽  
Individual Response ◽  
Altitude Training ◽  
Moderate Altitude ◽  
Red Cell ◽  
Red Cell Volume ◽  
The Individual

Moderate-altitude living (2,500 m), combined with low-altitude training (1,250 m) (i.e., live high-train low), results in a significantly greater improvement in maximal O2 uptake (V˙o 2 max) and performance over equivalent sea-level training. Although the mean improvement in group response with this “high-low” training model is clear, the individual response displays a wide variability. To determine the factors that contribute to this variability, 39 collegiate runners (27 men, 12 women) were retrospectively divided into responders ( n = 17) and nonresponders ( n = 15) to altitude training on the basis of the change in sea-level 5,000-m run time determined before and after 28 days of living at moderate altitude and training at either low or moderate altitude. In addition, 22 elite runners were examined prospectively to confirm the significance of these factors in a separate population. In the retrospective analysis, responders displayed a significantly larger increase in erythropoietin (Epo) concentration after 30 h at altitude compared with nonresponders. After 14 days at altitude, Epo was still elevated in responders but was not significantly different from sea-level values in nonresponders. The Epo response led to a significant increase in total red cell volume andV˙o 2 max in responders; in contrast, nonresponders did not show a difference in total red cell volume or V˙o 2 maxafter altitude training. Nonresponders demonstrated a significant slowing of interval-training velocity at altitude and thus achieved a smaller O2 consumption during those intervals, compared with responders. The acute increases in Epo and V˙o 2 maxwere significantly higher in the prospective cohort of responders, compared with nonresponders, to altitude training. In conclusion, after a 28-day altitude training camp, a significant improvement in 5,000-m run performance is, in part, dependent on 1) living at a high enough altitude to achieve a large acute increase in Epo, sufficient to increase the total red cell volume andV˙o 2 max, and 2) training at a low enough altitude to maintain interval training velocity and O2 flux near sea-level values.

The effect of the combined application of a low-intensity infrared laser and normobaric hypoxia on the clinical picture of chronic generalized periodontitis

2021 ◽  
pp. 40-47
Author(s):  
Ilona Vasilievna Dzgoeva ◽  
Anna Aleksandrovna Remizova ◽  
Valeriy Konstantinovich Frolkov ◽  
Sergey Nikolaevich Nagornev
Keyword(s):  
Therapeutic Effect ◽  
Clinical Signs ◽  
Physical Nature ◽  
Infrared Laser ◽  
Low Energy ◽  
Normobaric Hypoxia ◽  
Hypoxic Exposure ◽  
Combined Application ◽  
Biological Potential ◽  
Leading Position

Chronic generalized periodontitis still occupies a leading position among dental diseases, but the effectiveness of drug therapy is insufficient. One of the promising methods of non-drug treatment is the use of factors of various physical nature, which allows to have a therapeutic effect on various functional systems. The combined use of normobaric hypoxia and a low-energy infrared laser significantly increases the effectiveness of complex treatment of patients with chronic generalized periodontitis. At the same time, the regression of clinical signs of the disease was noted to a greater extent when using laser radiation compared to hypoxic exposure. Taking into account the fundamentally different mechanisms of realization of the biological potential of a low-energy infrared laser and normobaric hypoxia, it can be assumed that the increase in the effectiveness of treatment of patients with chronic generalized periodontitis is due to the additive or potentiating nature of the therapeutic effect when they are combined.

scholarly journals Ice-dynamic projections of the Greenland ice sheet in response to atmospheric and oceanic warming

2015 ◽  
Vol 9 (3) ◽  
pp. 1039-1062 ◽  
Author(s):  
J. J. Fürst ◽  
H. Goelzer ◽  
P. Huybrechts
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Flow Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Water Runoff ◽  
Strong Impact ◽  
Ice Dynamics ◽  
Over Time ◽  
Loss Rates

Abstract. Continuing global warming will have a strong impact on the Greenland ice sheet in the coming centuries. During the last decade (2000–2010), both increased melt-water runoff and enhanced ice discharge from calving glaciers have contributed 0.6 ± 0.1 mm yr−1 to global sea-level rise, with a relative contribution of 60 and 40% respectively. Here we use a higher-order ice flow model, spun up to present day, to simulate future ice volume changes driven by both atmospheric and oceanic temperature changes. For these projections, the flow model accounts for runoff-induced basal lubrication and ocean warming-induced discharge increase at the marine margins. For a suite of 10 atmosphere and ocean general circulation models and four representative concentration pathway scenarios, the projected sea-level rise between 2000 and 2100 lies in the range of +1.4 to +16.6 cm. For two low emission scenarios, the projections are conducted up to 2300. Ice loss rates are found to abate for the most favourable scenario where the warming peaks in this century, allowing the ice sheet to maintain a geometry close to the present-day state. For the other moderate scenario, loss rates remain at a constant level over 300 years. In any scenario, volume loss is predominantly caused by increased surface melting as the contribution from enhanced ice discharge decreases over time and is self-limited by thinning and retreat of the marine margin, reducing the ice–ocean contact area. As confirmed by other studies, we find that the effect of enhanced basal lubrication on the volume evolution is negligible on centennial timescales. Our projections show that the observed rates of volume change over the last decades cannot simply be extrapolated over the 21st century on account of a different balance of processes causing ice loss over time. Our results also indicate that the largest source of uncertainty arises from the surface mass balance and the underlying climate change projections, not from ice dynamics.

A Clinician Guide to Altitude Training for Optimal Endurance Exercise Performance at Sea Level

2017 ◽  
Vol 18 (2) ◽  
pp. 93-101 ◽  
Author(s):  
Keren Constantini ◽  
Daniel P. Wilhite ◽  
Robert F. Chapman
Keyword(s):  
Sea Level ◽  
Endurance Exercise ◽  
Exercise Performance ◽  
Altitude Training

Limb skeletal muscle adaptation in athletes after training at altitude

1990 ◽  
Vol 68 (2) ◽  
pp. 496-502 ◽  
Author(s):  
M. Mizuno ◽  
C. Juel ◽  
T. Bro-Rasmussen ◽  
E. Mygind ◽  
B. Schibye ◽  
...  
Keyword(s):  
Sea Level ◽  
Enzyme Activities ◽  
Buffer Capacity ◽  
Altitude Training ◽  
Mitochondrial Enzyme ◽  
Muscle Adaptation ◽  
Short Term ◽  
Vo2 Max ◽  
Capillary Supply ◽  
O2 Deficit

Morphological and biochemical characteristics of biopsies obtained from gastrocnemius (GAS) and triceps brachii muscle (TRI), as well as maximal O2 uptake (VO2 max) and O2 deficit, were determined in 10 well-trained cross-country skiers before and after a 2-wk stay (2,100 m above sea level) and training (2,700 m above sea level) at altitude. On return to sea level, VO2 max was the same as the prealtitude value, whereas an increase in O2 deficit (29%) and in short-term running performance (17%) was observed (P less than 0.05). GAS showed maintained capillary supply but a 10% decrease in mitochondrial enzyme activities (P less than 0.05), whereas an increase in capillary supply (P less than 0.05) but unchanged mitochondrial enzyme activities were observed in TRI. Buffer capacity was increased by 6% in both GAS and TRI (P less than 0.05). A positive correlation was found between the relative increase in buffer capacity of GAS and short-term running time (P less than 0.05). Thus the present study indicates no effect of 2 wk of altitude training on VO2 max but provides evidence to suggest an improvement in short-term exercise performance, which may be the result of an increase in muscle buffer capacity.

Performance of runners and swimmers after four weeks of intermittent hypobaric hypoxic exposure plus sea level training

2007 ◽  
Vol 103 (5) ◽  
pp. 1523-1535 ◽  
Author(s):  
Ferran A. Rodríguez ◽  
Martin J. Truijens ◽  
Nathan E. Townsend ◽  
James Stray-Gundersen ◽  
Christopher J. Gore ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Sea Level ◽  
Oxygen Transport ◽  
Hypobaric Hypoxia ◽  
Ventilatory Threshold ◽  
Controlled Trial ◽  
Intervention Group ◽  
Sport Performance ◽  
Hypoxic Exposure ◽  
Significant Difference

This double-blind, randomized, placebo-controlled trial examined the effects of 4 wk of resting exposure to intermittent hypobaric hypoxia (IHE, 3 h/day, 5 days/wk at 4,000–5,500 m) or normoxia combined with training at sea level on performance and maximal oxygen transport in athletes. Twenty-three trained swimmers and runners completed duplicate baseline time trials (100/400-m swims, or 3-km run) and measures for maximal oxygen uptake (V̇O2max), ventilation (V̇Emax), and heart rate (HRmax) and the oxygen uptake at the ventilatory threshold (V̇O2 at VT) during incremental treadmill or swimming flume tests. Subjects were matched for sex, sport, performance, and training status and divided randomly between hypobaric hypoxia (Hypo, n = 11) and normobaric normoxia (Norm, n = 12) groups. All tests were repeated within the first (Post1) and third weeks (Post2) after the intervention. Time-trial performance did not improve in either group. We could not detect a significant difference between groups for a change in V̇O2max, V̇Emax, HRmax, or V̇O2 at VT after the intervention (group × test interaction P = 0.31, 0.24, 0.26, and 0.12, respectively). When runners and swimmers were considered separately, Hypo swimmers appeared to increase V̇O2max (+6.2%, interaction P = 0.07) at Post2 following a precompetition taper and increased V̇O2 at VT (+8.9 and +12.1%, interaction P = 0.007 and 0.006, at Post1 and Post2). We conclude that this “dose” of IHE was not sufficient to improve performance or oxygen transport in this heterogeneous group of athletes. Whether there are potential benefits of this regimen for specific sports or training/tapering strategies may require further study.

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