Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillar...Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillary density, and economy. Physiological adaptations in response to acute and chronic exposure to hypoxic environments are well documented and range from short-term detrimental effects to longer-term adaptations that can improve performance at altitude and in sea-level competitions. Many altitude and hypoxic training protocols have been developed, employing various combinations of living and training at sea-level, low, moderate, and high altitudes and utilizing natural and artificial altitudes, with varying degrees of effectiveness. Several factors have been identified that are associated with individual responses to hypoxic training, and techniques for identifying those athletes most likely to benefit from hypoxic trairdng continue to be investigated. Exposure to sufficiently high altitude （2000-3000 m） for more than 12 h/day, while training at lower altitudes, for a minimum of 21 days is recommended. Timing of altitude training related to competition remains under debate, although general recommendations can be considered.展开更多
At the altitude,hypoxia and training load are key factors in the development of oxidative stress.Altitude-induced oxidative stress is developed due to the depletion of antioxidant potential.In the current study,we exa...At the altitude,hypoxia and training load are key factors in the development of oxidative stress.Altitude-induced oxidative stress is developed due to the depletion of antioxidant potential.In the current study,we examined the non-enzymatic antioxidant profile of blood plasma in 7 males and 5 females specializing in speed skating at a 21-day training camp at 1850m above sea level.Training included:cycling,roller skating,ice skating,strength training,and special training.At the start point and the endpoint,total hemoglobin mass(tHb-mass),hemoglobin concentration,and circulating blood volume were determined.Antioxidant profiles,hypoxic doses,hypoxic impulses,and training impulses were assessed at 3,6,10,14,and 18 days.Antioxidant profiles consisting of“urate”and“thiol”parts were registered with chemiluminometry.In the training dynamics,antioxidant parameters changed individually,but in total there was a decrease in the“urate”capacity by a factor of 1.6(p=0.001)and an increase in the“thiol”capacity by a factor of 1.8(p=0.013).The changes in“urate”capacity positively correlated(r_(S)=0.40)and the changes in“thiol”capacity negatively correlated(r_(S)=−0.45)with changes in tHb-mass.Both exercise and hypoxic factors affect the antioxidant parameters bidirectionally.They correlated with a decrease in thiol capacity and with an increase in urate capacity.The assessment of the non-enzymatic antioxidant profile can be a simple and useful addition to screening the reactive oxygen species homeostasis and can help choose the personalized training schedule,individualize recovery and ergogenic support.展开更多
Immune outcomes are key mediators of many health benefits of exercise and are determined by exercise type,dose(frequency/duration,intensity),and individual characteristics.Similarly,reduced availability of ambient oxy...Immune outcomes are key mediators of many health benefits of exercise and are determined by exercise type,dose(frequency/duration,intensity),and individual characteristics.Similarly,reduced availability of ambient oxygen(hypoxia)modulates immune functions depending on the hypoxic dose and the individual capacity to respond to hypoxia.How combined exercise and hypoxia(e.g.,high-altitude training)sculpts immune responses is not well understood,although such combinations are becoming increasingly popular.Therefore,in this paper,we summarize the impact on immune responses of exercise and of hypoxia,both independently and together,with a focus on specialized cells in the innate and adaptive immune system.We review the regulation of the immune system by tissue oxygen levels and the overlapping and distinct immune responses related to exercise and hypoxia,then we discuss how they may be modulated by nutritional strategies.Mitochondrial,antioxidant,and anti-inflammatory mechanisms underlie many of the adaptations that can lead to improved cellular metabolism,resilience,and overall immune functions by regulating the survival,differentiation,activation,and migration of immune cells.This review shows that exercise and hypoxia can impair or complement/synergize with each other while regulating immune system functions.Appropriate acclimatization,training,and nutritional strategies can be used to avoid risks and tap into the synergistic potentials of the poorly studied immune consequences of exercising in a hypoxic state.展开更多
Live high train high(LHTH)is the original method of altitude training used by elite athletes to enhance sea-level perfor-mance.Whilst many anecdotal reports featuring world-class performances of elite athletes at sea-...Live high train high(LHTH)is the original method of altitude training used by elite athletes to enhance sea-level perfor-mance.Whilst many anecdotal reports featuring world-class performances of elite athletes at sea-level following LHTH exist,well-controlled studies of elite athletes using altitude training under ecologically valid conditions with training well characterised are still lacking.The literature is equivocal when considering the ergogenic potential of LHTH,and given the majority of controlled studies do not report enhanced sea-level performance,some scepticism regarding the efficacy of LHTH persists.Despite this,LHTH remains a popular form of altitude training utilised by elite athletes,with numerous case studies of champion athletes employing LHTH solidifying the rationale for its use during preparation for competition.Discussion of factors affecting the response to LHTH are often related to compromising either the hypoxia induced acceleration of eryth-ropoiesis and production of red blood cells,or the maintenance of oxygen flux and training intensity at altitude.Regarding the former,iron status and supplementation,as well as hypoxic dose are often mentioned.Concerning the latter,reduced oxygen availability at altitude leading to athletes training at lower absolute intensities and the relative intensity of training sessions being clamped as equivalent to sea-level,thus also reducing absolute training intensity are frequently discussed.Other factors including immune function and the timing of competition following LHTH may also contribute to an observed performance.Less considered in the literature are those factors specific to elite athletes,namely the repeated use of altitude camps throughout a season,and the influence this may have on subsequent performance.The current narrative review aimed to summarise the current literature pertaining to LHTH in elite athletes,and furthermore describe several factors affecting performance following altitude training.展开更多
Hypoxia is an essential topic in medical or biological sciences.The main aims of the present study were to examine the most important medical articles(i.e.,the top 100 most cited)on hypoxia.We examine how the Nobel-pr...Hypoxia is an essential topic in medical or biological sciences.The main aims of the present study were to examine the most important medical articles(i.e.,the top 100 most cited)on hypoxia.We examine how the Nobel-prize awarded hypoxia inducible factor(HIF)-pathway discovery in the early 1990s has changed the thematic composition of this body of literature,with a special emphasis on the studies linking hypoxia and cancer.We searched Pubmed for articles with the terms#Hypox,#Altitude,or#Mountain in the title that have been published in biomedical journals and ranked the articles on their number of citations in Web of Science.A second search was performed in all journals for articles related to hypoxia and cancer.Strikingly,only 12 of the top-100 most-cited articles on hypoxia and only 3 articles of the top-100 articles related to cancer were published before 1995.Moreover,only 5 articles from prior 1995 reached 1000 citations,while 27 articles published in 1995 or later were cited more than 1000 times,most of them on the HIF-1 pathway.Eighty percent of the top-100 articles were related to the HIF pathway,while there were no articles on the application of hypoxia either for therapeutic use(i.e.,hypoxic conditioning in patients)or for performance enhancement(i.e.,altitude training in athletes).In conclusion,the early-1990s discovery of the HIF pathway and of its molecular regulation has shifted the focus of hypoxia research towards molecular mechanisms and consequences of tissue hypoxia,most notably in cancer.The importance of studies focusing on clinical and performance applications of systemic hypoxia is relatively lower.展开更多
Purpose Elite endurance runners frequently utilise live high-train high(LHTH)altitude training to improve endurance per-formance at sea level(SL).Individual variability in response to the hypoxic exposure have resulte...Purpose Elite endurance runners frequently utilise live high-train high(LHTH)altitude training to improve endurance per-formance at sea level(SL).Individual variability in response to the hypoxic exposure have resulted in contradictory findings.In the present case study,changes in total haemoglobin mass(tHbmass)and physiological capacity,in response to 4-weeks of LHTH were documented.We tested if a hypoxic sensitivity test(HST)could predict altitude-induced adaptations to LHTH.Methods Fifteen elite athletes were selected to complete 4-weeks of LHTH(~2400 m).Athletes visited the laboratory for preliminary testing(PRE),to determine lactate threshold(LT),lactate turn point(LTP),maximal oxygen uptake VO_(2max)and tHbmass.During LHTH,athletes completed daily physiological measures[arterial oxygen saturation(SpO2)and body mass]and subjective wellbeing questions.Testing was repeated,for those who completed the full camp,post-LHTH(POST).Additionally,athletes completed the HST prior to LHTH.Results A difference(P<0.05)was found from PRE to POST in average tHbmass(1.8%±3.4%),VO_(2max)(2.7%±3.4%),LT(6.1%±4.6%)and LTP(5.4%±3.8%),after 4-weeks LHTH.HST revealed a decrease in oxygen saturation at rest(ΔSp_(r))and higher hypoxic ventilatory response at rest(HVRr)predicted individual changes tHbmass.Lower hypoxic cardiac response at rest(HCRr)and higher HVRr predicted individual changes VO_(2max).Conclusion Four weeks of LHTH at~2400 m increased tHbmass and enhanced physiological capacity in elite endurance runners.There was no observed relationship between these changes and baseline characteristics,pre-LHTH serum ferritin levels,or reported incidents of musculoskeletal injury or illness.The HST did however,estimate changes in tHbmass and VO_(2max).HST prior to LHTH could allow coaches and practitioners to better inform the acclimatisation strategies and train-ing load application of endurance runners at altitude.展开更多
文摘Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillary density, and economy. Physiological adaptations in response to acute and chronic exposure to hypoxic environments are well documented and range from short-term detrimental effects to longer-term adaptations that can improve performance at altitude and in sea-level competitions. Many altitude and hypoxic training protocols have been developed, employing various combinations of living and training at sea-level, low, moderate, and high altitudes and utilizing natural and artificial altitudes, with varying degrees of effectiveness. Several factors have been identified that are associated with individual responses to hypoxic training, and techniques for identifying those athletes most likely to benefit from hypoxic trairdng continue to be investigated. Exposure to sufficiently high altitude （2000-3000 m） for more than 12 h/day, while training at lower altitudes, for a minimum of 21 days is recommended. Timing of altitude training related to competition remains under debate, although general recommendations can be considered.
文摘At the altitude,hypoxia and training load are key factors in the development of oxidative stress.Altitude-induced oxidative stress is developed due to the depletion of antioxidant potential.In the current study,we examined the non-enzymatic antioxidant profile of blood plasma in 7 males and 5 females specializing in speed skating at a 21-day training camp at 1850m above sea level.Training included:cycling,roller skating,ice skating,strength training,and special training.At the start point and the endpoint,total hemoglobin mass(tHb-mass),hemoglobin concentration,and circulating blood volume were determined.Antioxidant profiles,hypoxic doses,hypoxic impulses,and training impulses were assessed at 3,6,10,14,and 18 days.Antioxidant profiles consisting of“urate”and“thiol”parts were registered with chemiluminometry.In the training dynamics,antioxidant parameters changed individually,but in total there was a decrease in the“urate”capacity by a factor of 1.6(p=0.001)and an increase in the“thiol”capacity by a factor of 1.8(p=0.013).The changes in“urate”capacity positively correlated(r_(S)=0.40)and the changes in“thiol”capacity negatively correlated(r_(S)=−0.45)with changes in tHb-mass.Both exercise and hypoxic factors affect the antioxidant parameters bidirectionally.They correlated with a decrease in thiol capacity and with an increase in urate capacity.The assessment of the non-enzymatic antioxidant profile can be a simple and useful addition to screening the reactive oxygen species homeostasis and can help choose the personalized training schedule,individualize recovery and ergogenic support.
文摘Immune outcomes are key mediators of many health benefits of exercise and are determined by exercise type,dose(frequency/duration,intensity),and individual characteristics.Similarly,reduced availability of ambient oxygen(hypoxia)modulates immune functions depending on the hypoxic dose and the individual capacity to respond to hypoxia.How combined exercise and hypoxia(e.g.,high-altitude training)sculpts immune responses is not well understood,although such combinations are becoming increasingly popular.Therefore,in this paper,we summarize the impact on immune responses of exercise and of hypoxia,both independently and together,with a focus on specialized cells in the innate and adaptive immune system.We review the regulation of the immune system by tissue oxygen levels and the overlapping and distinct immune responses related to exercise and hypoxia,then we discuss how they may be modulated by nutritional strategies.Mitochondrial,antioxidant,and anti-inflammatory mechanisms underlie many of the adaptations that can lead to improved cellular metabolism,resilience,and overall immune functions by regulating the survival,differentiation,activation,and migration of immune cells.This review shows that exercise and hypoxia can impair or complement/synergize with each other while regulating immune system functions.Appropriate acclimatization,training,and nutritional strategies can be used to avoid risks and tap into the synergistic potentials of the poorly studied immune consequences of exercising in a hypoxic state.
文摘Live high train high(LHTH)is the original method of altitude training used by elite athletes to enhance sea-level perfor-mance.Whilst many anecdotal reports featuring world-class performances of elite athletes at sea-level following LHTH exist,well-controlled studies of elite athletes using altitude training under ecologically valid conditions with training well characterised are still lacking.The literature is equivocal when considering the ergogenic potential of LHTH,and given the majority of controlled studies do not report enhanced sea-level performance,some scepticism regarding the efficacy of LHTH persists.Despite this,LHTH remains a popular form of altitude training utilised by elite athletes,with numerous case studies of champion athletes employing LHTH solidifying the rationale for its use during preparation for competition.Discussion of factors affecting the response to LHTH are often related to compromising either the hypoxia induced acceleration of eryth-ropoiesis and production of red blood cells,or the maintenance of oxygen flux and training intensity at altitude.Regarding the former,iron status and supplementation,as well as hypoxic dose are often mentioned.Concerning the latter,reduced oxygen availability at altitude leading to athletes training at lower absolute intensities and the relative intensity of training sessions being clamped as equivalent to sea-level,thus also reducing absolute training intensity are frequently discussed.Other factors including immune function and the timing of competition following LHTH may also contribute to an observed performance.Less considered in the literature are those factors specific to elite athletes,namely the repeated use of altitude camps throughout a season,and the influence this may have on subsequent performance.The current narrative review aimed to summarise the current literature pertaining to LHTH in elite athletes,and furthermore describe several factors affecting performance following altitude training.
文摘Hypoxia is an essential topic in medical or biological sciences.The main aims of the present study were to examine the most important medical articles(i.e.,the top 100 most cited)on hypoxia.We examine how the Nobel-prize awarded hypoxia inducible factor(HIF)-pathway discovery in the early 1990s has changed the thematic composition of this body of literature,with a special emphasis on the studies linking hypoxia and cancer.We searched Pubmed for articles with the terms#Hypox,#Altitude,or#Mountain in the title that have been published in biomedical journals and ranked the articles on their number of citations in Web of Science.A second search was performed in all journals for articles related to hypoxia and cancer.Strikingly,only 12 of the top-100 most-cited articles on hypoxia and only 3 articles of the top-100 articles related to cancer were published before 1995.Moreover,only 5 articles from prior 1995 reached 1000 citations,while 27 articles published in 1995 or later were cited more than 1000 times,most of them on the HIF-1 pathway.Eighty percent of the top-100 articles were related to the HIF pathway,while there were no articles on the application of hypoxia either for therapeutic use(i.e.,hypoxic conditioning in patients)or for performance enhancement(i.e.,altitude training in athletes).In conclusion,the early-1990s discovery of the HIF pathway and of its molecular regulation has shifted the focus of hypoxia research towards molecular mechanisms and consequences of tissue hypoxia,most notably in cancer.The importance of studies focusing on clinical and performance applications of systemic hypoxia is relatively lower.
文摘Purpose Elite endurance runners frequently utilise live high-train high(LHTH)altitude training to improve endurance per-formance at sea level(SL).Individual variability in response to the hypoxic exposure have resulted in contradictory findings.In the present case study,changes in total haemoglobin mass(tHbmass)and physiological capacity,in response to 4-weeks of LHTH were documented.We tested if a hypoxic sensitivity test(HST)could predict altitude-induced adaptations to LHTH.Methods Fifteen elite athletes were selected to complete 4-weeks of LHTH(~2400 m).Athletes visited the laboratory for preliminary testing(PRE),to determine lactate threshold(LT),lactate turn point(LTP),maximal oxygen uptake VO_(2max)and tHbmass.During LHTH,athletes completed daily physiological measures[arterial oxygen saturation(SpO2)and body mass]and subjective wellbeing questions.Testing was repeated,for those who completed the full camp,post-LHTH(POST).Additionally,athletes completed the HST prior to LHTH.Results A difference(P<0.05)was found from PRE to POST in average tHbmass(1.8%±3.4%),VO_(2max)(2.7%±3.4%),LT(6.1%±4.6%)and LTP(5.4%±3.8%),after 4-weeks LHTH.HST revealed a decrease in oxygen saturation at rest(ΔSp_(r))and higher hypoxic ventilatory response at rest(HVRr)predicted individual changes tHbmass.Lower hypoxic cardiac response at rest(HCRr)and higher HVRr predicted individual changes VO_(2max).Conclusion Four weeks of LHTH at~2400 m increased tHbmass and enhanced physiological capacity in elite endurance runners.There was no observed relationship between these changes and baseline characteristics,pre-LHTH serum ferritin levels,or reported incidents of musculoskeletal injury or illness.The HST did however,estimate changes in tHbmass and VO_(2max).HST prior to LHTH could allow coaches and practitioners to better inform the acclimatisation strategies and train-ing load application of endurance runners at altitude.
