低氧训练对大鼠骨骼肌血红素氧合酶mRNA表达的影响

目的:探讨不同低氧训练模式对机体骨骼肌血红素合酶(HO-1)mRNA表达的影响。方法:选用6周龄SD雄性大鼠120只,经3周适应性训练和力竭实验筛选出90只,随机分成9组:常氧安静对照组、持续低氧安静组、间歇低氧安静组、低住低练组、高住高练组、高住低练组、低住高练组、高住高练后复氧训练组、高住低练后复氧训练组。采用常压低氧舱以13.6%的氧浓度(相当于海拔3500m的氧浓度)进行低氧训练,根据血乳酸-速度曲线确定大鼠常氧训练的强度为35m/min,低氧训练的强度为30m/min。低氧训练持续时间为6周,每周训练5天。第6周末最后一次运动后休息48h后处死、取材。采用实时荧光定量PCR技术测试大鼠骨骼肌HO-1mRNA表达。结果:与常氧安静对照组相比,低住低练组大鼠骨骼肌HO-1mRNA表达显著升高(P<0.05),高住高练组、低住高练组非常显著升高(P<0.01);高住低练组与低住低练组比较显著降低(P<0.05);高住高练后复氧训练组大鼠骨骼肌HO-1mRNA表达与高住高练组相比显著降低(P<0.01),基本回到常氧安静对照组水平。结论:高住高练和低住高练可提骨骼肌HO-1mRNA表达。     

不同低氧训练模式对大鼠腓肠肌有氧代谢酶活性的影响

目的:探讨三种低氧训练模式对大鼠腓肠肌有氧代谢酶活性的影响。方法:经过适应性训练和力竭实验筛选出40只雄性SD大鼠,采用双盲法平均分成4组:低住低练组、高住高练组、高住低练组和低住高练组。采用水平动物跑台进行耐力训练,运动强度为常氧下35m/min、低氧下30m/min,1h/d,5d/周,持续训练6周。低住低练组大鼠在常氧环境下生活训练;高住高练组大鼠在低氧环境(氧浓度为13.6%,约相当于海拔3500m高度)生活训练;高住低练组大鼠低氧环境生活12h,常氧环境训练;低住高练组大鼠在常氧环境生活,低氧环境训练。最后一次训练后恢复48h取腓肠肌,检测柠檬酸合成酶(CS)、琥珀酸脱氢酶(SDH)和苹果酸脱氢酶(MDH)活性。结果:与低住低练组比较,高住高练组大鼠腓肠肌CS、SDH和MDH活性分别升高11.7%(P<0.01)、8.7%(P<0.05)和12.5%(P<0.01);高住低练组、低住高练组较低住低练组增加,但无统计学意义。结论:3500米三种低氧训练模式就提高机体有氧代谢酶活性而言,高住高练优于高住低练和低住高练。     

Classical altitude training

For more than 40 years, the effects of classical altitude training on sea-level performance have been the subject of many scientific investigations in individual endurance sports. To our knowledge, no studies have been performed in team sports like football. Two well-controlled studies showed that living and training at an altitude of ≥1800–2700 m for 3–4 weeks is superior to equivalent training at sea level in well-trained athletes. Most of the controlled studies with elite athletes did not reveal such an effect. However, the results of some uncontrolled studies indicate that sea-level performance might be enhanced after altitude training also in elite athletes. Whether hypoxia provides an additional stimulus for muscular adaptation, when training is performed with equal intensity compared with sea-level training is not known. There is some evidence for an augmentation of total hemoglobin mass after classical altitude training with duration ≥3 weeks at an altitude ≥2000 m due to altitude acclimatization. Considerable individual variation is observed in the erythropoietic response to hypoxia and in the hypoxia-induced reduction of aerobic performance capacity during training at altitude, both of which are thought to contribute to inter-individual variation in the improvement of sea-level performance after altitude training.     

Intermittent hypoxic training: fact and fancy

Intermittent hypoxic training (IHT) refers to the discontinuous use of normobaric or hypobaric hypoxia, in an attempt to reproduce some of the key features of altitude acclimatization, with the ultimate goal to improve sea-level athletic performance. In general, IHT can be divided into two different strategies: (1) providing hypoxia at rest with the primary goal being to stimulate altitude acclimatization or (2) providing hypoxia during exercise, with the primary goal being to enhance the training stimulus. Each approach has many different possible application strategies, with the essential variable among them being the "dose" of hypoxia necessary to achieve the desired effect. One approach, called living high-training low, has been shown to improve sea-level endurance performance. This strategy combines altitude acclimatization (2500 m) with low altitude training to ensure high-quality training. The opposite strategy, living low-training high, has also been proposed by some investigators. The primacy of the altitude acclimatization effect in IHT is demonstrated by the following facts: (1) living high-training low clearly improves performance in athletes of all abilities, (2) the mechanism of this improvement is primarily an increase in erythropoietin, leading to increased red cell mass, V(O2max), and running performance, and (3) rather than intensifying the training stimulus, training at altitude or under hypoxia leads to the opposite effect - reduced speeds, reduced power output, reduced oxygen flux - and therefore is not likely to provide any advantage for a well-trained athlete.     

高住高练和高住低练对大鼠血脂及腓肠肌脂肪酸氧化的影响

目的:从血脂和脂肪酸氧化的角度研究高住高练和高住低练对大鼠脂代谢的影响。方法:经适应性训练筛选30只雄性SD大鼠,采用双盲法分成低住低练组(LoLo)、高住高练组(HiHi)和高住低练组(HiLo)。采用水平动物跑台进行耐力训练,运动强度为常氧下35m/min、低氧下30m/min,1h/d,6d/周,持续训练4周。最后一次训练后恢复24h取血和腓肠肌。全自动生化分析仪检测血脂4项,ELISA法检测血清脂蛋白酯酶(LPL)、瘦素(Leptin)、脂联素(AD),荧光定量PCR测试腓肠肌PPARα和CPT-1 mRNA表达。结果:高住高练组大鼠血清TC和TG水平较低住低练组显著下降(P<0.05),LPL、AD水平显著升高(P<0.01);腓肠肌PPARαmRNA和CPT-1 mRNA表达均显著升高(P<0.05),其它指标无显著性差异。高住低练组大鼠血清HDL较低住低练组显著降低(P<0.05);腓肠肌CPT-1 mRNA相对表达量显著降低(P<0.01);其余指标无显著性变化。高住高练组大鼠血清HDL较高住低练组显著升高(P<0.05);LPL、AD水平和腓肠肌CPT-1 mRNA显著升高(P<0.01),其余指标无显著性差异。结论:(1)高住高练调节血脂变化的作用优于常氧训练,可能与提高血清LPL水平有关,高住高练较常氧训练更能促进腓肠肌脂肪酸氧化,可能与提高血清AD和腓肠肌PPARαmRNA、CPT-1 mRNA表达关系密切;(2)高住低练较常氧训练对血脂代谢无有利影响,对腓肠肌脂肪酸氧化起抑制作用;(3)高住高练对血清HDL影响优于高住低练,可能与提高血清LPL有关,高住高练较高住低练更能促进腓肠肌脂肪酸氧化,可能与提高血清AD和腓肠肌CPT-1mRNA表达关系密切。     

Physiological effects of intermittent hypoxia

Intermittent hypoxia (IH), or periodic exposure to hypoxia interrupted by return to normoxia or less hypoxic conditions, occurs in many circumstances. In high altitude mountaineering, IH is used to optimize acclimatization although laboratory studies have not generally revealed physiologically significant benefits. IH enhances athletic performance at sea level if blood oxygen capacity increases and the usual level of training is not decreased significantly. IH for high altitude workers who commute from low altitude homes is of considerable practical interest and the ideal commuting schedule for physical and mental performance is being studied. The effect of oxygen enrichment at altitude (i.e., intermittent normoxia on a background of chronic hypoxia) on human performance is under study also. Physiological mechanisms of IH, and specifically the differences between effects of IH and acute or chronic continuous hypoxia remains to be determined. Biomedical researchers are defining the molecular and cellular mechanisms for effects of hypoxia on the body in health and disease. A comparative approach may provide additional insight about the biological significance of these effects.     

高住低练对大鼠肝组织低氧诱导因子-1α蛋白表达的影响

目的:探讨不同持续时间低氧后运动训练(高住低练)对大鼠肝组织低氧诱导因子-1α(HIF-1α)蛋白表达的影响。方法:将60只雄性SD大鼠随机分为6组,每组10只:安静对照组不训练,不进行低氧暴露;两低氧暴露组和两高住低练组每天分别进行8小时或12小时低氧暴露(氧浓度12.6%,相当于海拔4000m);同时,训练对照组和两高住低练组每天均以25m/min的速度进行跑台训练1h,每周5天,共4周。采用免疫组织化学的方法检测各组大鼠肝组织HIF-1α的蛋白表达,并采用计算机显微图像分析系统进行HIF-1α定位及阳性表达定量分析。结果:与安静对照组相比,不论是单纯低氧暴露组、单纯训练组或者高住低练组HIF-1α蛋白表达均显著增加(P<0.05);12小时低氧暴露组HIF-1α蛋白表达灰度值比8小时稍增高,无统计学意义(P>0.05),而阳性物质表达面积和PI显著增加(P<0.05);与训练对照组比较,8小时和12小时高住低练组HIF-1α蛋白表达增加,具有统计学意义(P<0.05,P<0.01);8小时高住低练组HIF-1α蛋白表达比8小时低氧暴露组显著增加(P<0.05),12小时高住低练组HIF-1α蛋白表达比12小时低氧暴露组显著增加(P<0.05,P<0.01);与8小时高住低练组相比,12小时高住低练组HIF-1α蛋白表达显著增加(P<0.05)。结论:(1)不论单纯低氧暴露、单纯训练或者高住低练均能促进肝组织HIF-1α蛋白表达增加;(2)高住低练过程中肝组织HIF-1α蛋白表达高于单纯低氧暴露或单纯训练方式,不同持续时间低氧后运动对大鼠肝组织HIF-1α蛋白表达的影响不同。     

Live and/or sleep high:train low, using normobaric hypoxia

The increase in oxygen transport elicited by several weeks of exposure to moderate to high altitude is used to increase physical performance when returning to sea level. However, many studies have shown that aerobic performance may not increase at sea level after a training block at high altitude. Subsequently, the concept of living high and training low was introduced in the early 1990s and was further modified to include simulated altitude using hypobaric or normobaric hypoxia. Review is given of the main studies that have used this procedure. Hematological changes are limited to insignificant or moderate increase in red cell mass, depending on the "dose" of hypoxia. Maximal aerobic performance is increased when the exposure to hypoxia is at least over 18 days. Submaximal performance and running economy have been found increased in several, but not all, studies. The tolerance (fatigue, sleep, immunological status, cardiac function) is good when the altitude or simulated altitude is not higher than 3000 m. Virtually no data are available about the effect of this procedure upon anaerobic performance. The wide spread of these techniques deserves further investigations.     

Altitude negates the benefits of aerobic training on the vascular adaptations in rats

INTRODUCTION: This study questioned the effect of living and training at moderate altitude on aortic vasoreactivity. Considering that chronic hypoxia exposure and endurance training are able to generate opposite effects on the systemic vascular reactivity, it was hypothesized that endurance training benefits on the vascular function could be limited by chronic hypoxia. METHODS: Sea-level native rats were randomly assigned to N (living in normoxia), NT (living and training 5 d.wk for 5 wk in normoxia), CH (living in hypoxia, 2800 m), and CHT (living and training 5 d.wk for 5 wk in hypoxia, 2800 m) groups. Concentration response curves to epinephrine, norepinephrine, endothelin-1, acetylcholine, and sodium nitro-prusside were assessed on aortic isolated rings. Left ventricular resting and maximal (during Tyrode's infusion) stroke volumes were evaluated by Doppler-echocardiography and used as indexes of chronic aortic volume overload. RESULTS: The main finding was that favorable aortic vasoreactivity adaptations consecutive to sea-level training were not observed when training was conducted at altitude. An improvement in the endothelium-dependent vasorelaxation (maximal relaxation, R(max), N = 60.4 +/- 10.0 vs NT = 91.7 +/- 3.2%; P < 0.05) and a reduced sensitivity to ET-1 were observed in NT rats. Such an enhancement in endothelium-dependent vasorelaxation was not found in CHT rats (R(max): 48.4 +/- 7.8%). Moreover, a higher sensitivity to ET-1 was reported in this group. Altitude-induced limitation in aortic blood flow and shear stress could play a major role in the explanation of these specific altitude-training adaptations. CONCLUSION: If extrapolated to the peripheral vascular bed, our results have practical significance for aerobic performance as aortic vasoreactivity adaptations after altitude training could contribute to limit blood delivery to exercising muscles.     

Effect of hypoxic "dose" on physiological responses and sea-level performance

Live high-train low (LH+TL) altitude training was developed in the early 1990s in response to potential training limitations imposed on endurance athletes by traditional live high-train high (LH+TH) altitude training. The essence of LH+TL is that it allows athletes to "live high" for the purpose of facilitating altitude acclimatization, as manifest by a profound and sustained increase in endogenous erythropoietin (EPO) and ultimately an augmented erythrocyte volume, while simultaneously allowing athletes 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 to conveniently bring the mountain to the athlete, including nitrogen apartments, hypoxic tents, and hypoxicator devices. One of the key questions regarding the practical application of LH+TL is, what is the optimal hypoxic dose needed to facilitate altitude acclimatization and produce the expected beneficial physiological responses and sea-level performance effects? The purpose of this paper is to objectively answer that question, on the basis of an extensive body of research by our group in LH+TL altitude training. We will address three key questions: 1) What is the optimal altitude at which to live? 2) How many days are required at altitude? and 3) How many hours per day are required? On the basis of consistent findings from our research group, we recommend that for athletes to derive the physiological benefits of LH+TL, they need to live at a natural elevation of 2000-2500 m for >or=4 wk for >or=22 h.d(-1).     

Preparation for football competition at moderate to high altitude

Analysis of ∼100 years of home-and-away South American World Cup matches illustrate that football competition at moderate/high altitude (>2000 m) favors the home team, although this is more than compensated by the likelihood of sea-level teams winning at home against the same opponents who have descended from altitude. Nevertheless, the home team advantage at altitudes above ∼2000 m may reflect that traditionally, teams from sea level or low altitude have not spent 1–2 weeks acclimatizing at altitude. Despite large differences between individuals, in the first few days at high altitude (e.g. La Paz, 3600 m) some players experience symptoms of acute mountain sickness (AMS) such as headache and disrupted sleep, and their maximum aerobic power (VO_2max) is ∼25% reduced while their ventilation, heart rate and blood lactate during submaximal exercise are elevated. Simulated altitude for a few weeks before competition at altitude can be used to attain partial ventilatory acclimation and ameliorated symptoms of AMS. The variety of simulated altitude exposures usually created with enriched nitrogen mixtures of air include resting or exercising for a few hours per day or sleeping ∼8 h/night in hypoxia. Preparation for competition at moderate/high altitude by training at altitude is probably superior to simulated exposure; however, the optimal duration at moderate/high altitude is unclear. Preparing for 1–2 weeks at moderate/high altitude is a reasonable compromise between the benefits associated with overcoming AMS and partial restoration of VO_2max vs the likelihood of detraining.     

Intermittent hypoxia does not increase exercise ventilation at simulated moderate altitude

Recent human studies have shown that resting hypoxic ventilatory response (HVR), which is an index of ventilatory chemosensitivity to hypoxia, increased after short-term intermittent hypoxia at rest. In addition, intermittent hypoxia leads to increases in ventilation and arterial oxygen saturation (SaO (2)) during exercise at simulated high altitude, with the increase in ventilation correlated to the change in HVR. However, no study has been made to clarify the relationship between ventilatory chemosensitivity and the exercise ventilation at moderate altitude following intermittent hypoxia during a resting state. The purpose of the present study, therefore, was to elucidate whether intermittent hypoxia at rest induces the increase in ventilation during exercise at moderate altitude that is accompanied by an increase in hypoxic chemosensitivity. Eighteen trained male runners were assigned to three groups, i.e., the first hypoxic group (H-1 group, n = 6), the second hypoxic group (H-2 group, n = 6), and a control group (C group, n = 6). The hypoxic tent system was utilized for intermittent hypoxia, and the oxygen levels in the tent were maintained at 15.5 +/- 0.1 % (simulated 2500 m altitude) for the H-1 group and 12.3 +/- 0.2 % (simulated 4300 m altitude) for the H-2 group. The H-1 and H-2 groups spent 1 hour per day in the hypoxic tent for 1 week. Maximal and submaximal exercise tests while breathing 15.5 +/- 0.01 % O (2) (simulated altitude of 2500 m) were performed before and after intermittent hypoxia. Resting HVR was also determined in each subject using a progressive isocapnic hypoxic method. In the H-2 group, HVR increased significantly (p < 0.05) following intermittent hypoxia, while no change in HVR was found in the H-1 or C group. Neither ventilation nor SaO (2) during maximal and submaximal exercise at a simulated altitude of 2500 m were changed in either group after 1 hour per day for 1 week of intermittent hypoxia. These results suggest that the change in resting hypoxic chemosensitivity after short-term intermittent hypoxia does not affect ventilation during exercise at moderate altitude.     

不同低氧训练模式对大鼠脑组织线粒体呼吸链酶复合体活性的影响

目的:探讨不同低氧训练模式对大鼠脑线粒体呼吸链功能的影响。方法:40只健康2月龄雄性Wistar大鼠随机均分为5组:常氧训练组(LoLo)、高住高练组(HiHi)、高住低训组(HiLo)、低住高练组(LoHi)和高住高练低训组(HiHiLo),每组8只。依实验方案,各组大鼠分别在常氧(模拟海拔1500m,大气压为632mmHg)或/和低氧(模拟海拔3500m,大气压为493mmHg)环境中居住及递增负荷训练5周,每周训练6天。最后一次训练后在常氧环境恢复72h,力竭运动后即刻取样。差速离心提取线粒体。分光光度法测定呼吸链酶复合体(CⅠ～CⅢ)活性。结果:4个低氧训练组大鼠脑组织线粒体呼吸链CⅠ活性与LoLo组相比均无显著性差异。LoHi组CⅡ活性显著下降(P<0.01),降低76.199%,其余各组无显著性差异。HiHi组、HiLo组和LoHi组CⅢ活性均显著下降(P<0.01),分别降低71.496%、65.240%和87.838%,HiHiLo组显著性上升(P<0.01),提高170.145%。结论:在模拟海拔3500m的4种低氧训练中,髙住高练低训提高大鼠脑组织线粒体呼吸链功能的作用优于髙住高练、高住低训和低住高练。     

Sea-level performance in runners using altitude tents: A field study

In this study of effects of simulated altitude exposure on sea-level performance, 10 competitive runners slept in a hypoxic environment achieved with tents for 9.8+/-1.3 h.d(-1) (mean+/-standard deviation) for 24 days-30 days at 2500-3500 m (PIO2=117-103 mmHg) above sea level. The altitude group and a control group of 10 runners performed usual training (PIO2=149 mmHg). At approximately 4-wk intervals before and after exposure both groups performed an incremental test for lactate threshold. The altitude group performed an additional test, a treadmill run to exhaustion lasting approximately 5 min. One week following exposure lactate threshold speed of the altitude group relative to the control group increased by 1.2% (90% likely limits +/-3.1%), but the effect became slightly negative after controlling for baseline differences in running speed between the groups. A 16% increase in time to exhaustion was observed in the altitude group, equivalent to a 1.9% (+/-1.4%) increase in speed in a time trial. Change in performance had an unclear relationship to total altitude exposure, genotype for angiotensin converting enzyme, and change in haemoglobin concentration. Our findings are consistent with little or no effect of use of altitude tents on sea-level performance.     

模拟不同海拔高住低练对大鼠心肌VEGF和HSP70的影响

目的:探讨模拟不同海拔高住低练对大鼠心肌保护性蛋白热休克蛋白70(HSP70)和血管内皮生长因子(VEGF)表达的影响。方法:适应性喂养1周后,将48只SD大鼠按体重随机分为6组:常氧对照组(C)、14.5%O2低氧暴露组(14.5%O2LH)、12.7%O2低氧暴露组(12.7O2LH)、常氧训练组(TL)、14.5%O2高住低练组(14.5%O2LiLo)、12.7%O2高住低练组(12.7%O2HiLo),每组8只。采用20.9%、14.5%和12.7%三种氧浓度暴露和运动强度逐渐递增的高住低练模型,两LH组每天在低压氧舱中放置22 h后2 h舱外常氧生活,两HiLo组每天在低压氧舱中放置22 h后常氧生活1 h,再常氧训练1 h,所有进行低氧暴露的动物每周实验6天;TL组和两HiLo组进行一次5～10 min跑台适应性训练(速度为16 m/min,坡度为0)后,每天训练速度为35m/min,运动时间从30 min至60 min递增,每3天增加5 min,每天训练1次,每周6天,共4周。实验方案结束后24 h,麻醉大鼠取大鼠心尖肌组织,采用免疫组织化学技术检测VEGF和HSP70表达。结果:(1)与C组比较,14.5%O2LH组、TL组和12.7%O2的HiLo组VEGF阳性物质表达量显著增加(Ρ<0.05),12.7%O2LH组增加不显著(Ρ>0.05),而14.5%O2HiLo组表达量增加非常显著(Ρ<0.01);14.5%O2LH组VEGF阳性物质表达量较12.7%O2LH组显著增加(Ρ<0.05),12.7%O2HiLo组比14.5%O2HiLo组显著降低(Ρ<0.05),14.5%O2HiLo组VEGF阳性物质表达量较14.5%O2LH组显著增加(Ρ<0.05)。(2)与C组相比较,14.5%O2LH组、14.5%O2和12.7%O2两HiLo组HSP70阳性物质表达量增加(Ρ<0.05),12.7%O2LH组表达最明显,而TL组增加不显著(Ρ>0.05);14.5%O2LH和HiLo两组HSP70阳性物质表达量分别比12.7%O2LH和HiLo两组显著降低(Ρ<0.05),而两LH组HSP70阳性物质表达量分别与两HiLo组相比无显著性差异(Ρ>0.05)。结论:单纯低氧暴露、常氧运动及高住低练三种应激因素均诱导细胞保护性蛋白VEGF和HSP70表达;14.5%O2HiLo组的VEGF表达最显著,而12.7%O2LH组的HSP70表达最显著。     

Training high--living low: changes of aerobic performance and muscle structure with training at simulated altitude.

This study was undertaken to test the hypothesis that endurance training in hypoxia is superior to training of the same intensity in normoxia. To avoid adaptation to hypoxia, the subjects lived under normoxic conditions when not training. A secondary objective of this study was to compare the effect of high- vs. moderate-intensity training on aerobic performance variables. Thirty-three men without prior endurance training underwent a cycle ergometer training of 6 weeks, 5 d/week, 30 minutes/d. The subjects were assigned to 4 groups, N-high, N-low, H-high and H-low based on the training criteria normoxia (N; corresponding to a training altitude of 600 m), vs. hypoxia (H; training altitude 3850 m) and intensity (high; corresponding to 80% and low: corresponding to 67% of VO2max). VO2max measured in normoxia increased between 8.5 to 11.1%, independent of training altitude or intensity. VO2max measured in hypoxia increased between 2.9 and 7.2%. Hypoxia training resulted in significantly larger increases than normoxia training. Maximal power that subjects could maintain over a thirty-minute period (measured in normoxia or hypoxia) increased from 12.3 - 26.8% independent of training altitude. However, subjects training at high intensity increased performance more than subjects training at a low intensity. Muscle volume of the knee-extensors as measured by magnetic resonance imaging increased significantly in the H-high group only (+ 5.0%). Mitochondrial volume density measured by EM-morphometry in biopsy samples of m. vastus lat. increased significantly in all groups with the highest increase seen in the H-high group (+ 59%). Capillary length density increased significantly in the H-high group only (+ 17.2%). The main finding of this study is that in previously untrained people, training in hypoxia while living at low altitude increases performance in normoxia to the same extent as training in normoxia, but leads to larger increases of aerobic performance variables when measured under hypoxic conditions. Training intensity had no effect on the gain of VO2max. On the level of skeletal muscle tissue, the combination of hypoxia with high training intensity constitutes the most effective stimulus for increasing muscle oxidative capacity.     

高住低训对优秀女子跆拳道运动员运动能力和血象的影响

目的:探讨高住低训对女子跆拳道运动员运动能力和血象的影响。方法:13名优秀女子跆拳道运动员随机分为实验组(高住低训,n=8)和对照组(n=5),分别在模拟海拔2500m低氧舱(氧浓度15.4%左右)内和平原环境下进行为期4周的高住低训和跆拳道常规专项训练。分别于实验前、高住低训第28天和高住低训结束后10天进行有氧运动能力和无氧运动能力测试,并于实验前1天、高住低训期间每周及高住低训结束后第3、12天清晨空腹取血进行血细胞分析。结果:(1)实验组高住低训第28天和高住低训结束后10天VO2max和PWC170均显著高于实验前(P<0.01),4000m成绩显著优于实验前(P<0.01)。对照组变化不明显。(2)实验组高住低训结束后10天Wingate最高功率显著高于对照组(P<0.05)。实验组高住低训第28天和高住低训结束后10天Wingate平均功率均显著高于自身实验前(P<0.05和P<0.01),Wingate疲劳指数则分别显著低于自身实验前(P<0.05和P<0.01)。对照组无明显变化。(3)实验组高住低训第28天血红蛋白、红细胞数目、红细胞压积显著高于自身实验前(P<0.05),实验组在高住低训第25天和28天血红蛋白水平分别显著高于对照组(P<0.05和P<0.01)。结果表明,为期28天的模拟海拔2500m高度的高住低训能提高女子跆拳道运动员有氧运动能力,同时在一定程度上提高其无氧功和60秒踢靶成绩。另外,高住低训可以提高与跆拳道运动员机体载氧能力直接相关的血液指标水平,这种改变主要表现在实验第3、4周。     

A three-week traditional altitude training increases hemoglobin mass and red cell volume in elite biathlon athletes

It is well known that altitude training stimulates erythropoiesis, but only few data are available concerning the direct altitude effect on red blood cell volume (RCV) in world class endurance athletes during exposure to continued hypoxia. The purpose of this study was to evaluate the impact of three weeks of traditional altitude training at 2050 m on total hemoglobin mass (tHb), RCV and erythropoietic activity in highly-trained endurance athletes. Total hemoglobin mass, RCV, plasma volume (PV), and blood volume (BV) from 6 males and 4 females, all members of a world class biathlon team, were determined on days 1 and 20 during their stay at altitude as well as 16 days after returning to sea-level conditions (800 m, only males) by using the CO-rebreathing method. In males tHb (14.0 +/- 0.2 to 15.3 +/- 1.0 g/kg, p < 0.05) and RCV (38.9 +/- 1.5 to 43.5 +/- 3.9 ml/kg, p < 0.05) increased at altitude and returned to near sea-level values 16 days after descent. Similarly in females, tHb (13.0 +/- 1.0 to 14.2 +/- 1.3 g/kg, p < 0.05) and RCV (37.3 +/- 3.3 to 42.2 +/- 4.1 ml/kg, p < 0.05) increased. Compared to their sea-level values, the BV of male and female athletes showed a tendency to increase at the end of the altitude training period, whereas PV was not altered. In male athletes, plasma erythropoietin concentration increased up to day 4 at altitude (11.8 +/- 5.0 to 20.8 +/- 6.0 mU/ml, p < 0.05) and the plasma concentration of the soluble transferrin receptor was elevated by about 11 % during the second part of the altitude training period, both parameters indicating enhanced erythropoietic activity. In conclusion, we show for the first time that a three-week traditional altitude training increases erythropoietic activity even in world class endurance athletes leading to elevated tHb and RCV. Considering the relatively fast return of tHb and RCV to sea-level values after hypoxic exposure, our data suggest to precisely schedule training at altitude and competition at sea level.     

Physiological implications of altitude training for endurance performance at sea level: a review.

Acclimatisation to environmental hypoxia initiates a series of metabolic and musculocardio-respiratory adaptations that influence oxygen transport and utilisation, or better still, being born and raised at altitude, is necessary to achieve optimal physical performance at altitude, scientific evidence to support the potentiating effects after return to sea level is at present equivocal. Despite this, elite athletes continue to spend considerable time and resources training at altitude, misled by subjective coaching opinion and the inconclusive findings of a large number of uncontrolled studies. Scientific investigation has focused on the optimisation of the theoretically beneficial aspects of altitude acclimatisation, which include increases in blood haemoglobin concentration, elevated buffering capacity, and improvements in the structural and biochemical properties of skeletal muscle. However, not all aspects of altitude acclimatisation are beneficial; cardiac output and blood flow to skeletal muscles decrease, and preliminary evidence has shown that hypoxia in itself is responsible for a depression of immune function and increased tissue damage mediated by oxidative stress. Future research needs to focus on these less beneficial aspects of altitude training, the implications of which pose a threat to both the fitness and the health of the elite competitor. Paul Bert was the first investigator to show that acclimatisation to a chronically reduced inspiratory partial pressure of oxygen (P1O2) invoked a series of central and peripheral adaptations that served to maintain adequate tissue oxygenation in healthy skeletal muscle, physiological adaptations that have been subsequently implicated in the improvement in exercise performance during altitude acclimatisation. However, it was not until half a century later that scientists suggested that the additive stimulus of environmental hypoxia could potentially compound the normal physiological adaptations to endurance training and accelerate performance improvements after return to sea level. This has stimulated an exponential increase in scientific research, and, since 1984, 22 major reviews have summarised the physiological implications of altitude training for both aerobic and anaerobic performance at altitude and after return to sea level. Of these reviews, only eight have specifically focused on physical performance changes after return to sea level, the most comprehensive of which was recently written by Wolski et al. Few reviews have considered the potentially less favourable physiological responses to moderate altitude exposure, which include decreases in absolute training intensity, decreased plasma volume, depression of haemopoiesis and increased haemolysis, increases in sympathetically mediated glycogen depletion at altitude, and increased respiratory muscle work after return to sea level. In addition, there is a risk of developing more serious medical complications at altitude, which include acute mountain sickness, pulmonary oedema, cardiac arrhythmias, and cerebral hypoxia. The possible implications of changes in immune function at altitude have also been largely ignored, despite accumulating evidence of hypoxia mediated immunosuppression. In general, altitude training has been shown to improve performance at altitude, whereas no unequivocal evidence exists to support the claim that performance at sea level is improved. Table 1 summarises the theoretical advantages and disadvantages of altitude training for sea level performance. This review summarises the physiological rationale for altitude training as a means of enhancing endurance performance after return to sea level. Factors that have been shown to affect the acclimatisation process and the subsequent implications for exercise performance at sea level will also be discussed. Studies were located using five major database searches, which included Medline, Embase, Science Citation Index, Sports Discus, and Sport, in     

The effect of altitude on cycling performance: a challenge to traditional concepts.

Acute exposure to moderate altitude is likely to enhance cycling performance on flat terrain because the benefit of reduced aerodynamic drag outweighs the decrease in maximum aerobic power [maximal oxygen uptake (VO2max)]. In contrast, when the course is mountainous, cycling performance will be reduced at moderate altitude. Living and training at altitude, or living in an hypoxic environment (approximately 2500 m) but training near sea level, are popular practices among elite cyclists seeking enhanced performance at sea level. In an attempt to confirm or refute the efficacy of these practices, we reviewed studies conducted on highly-trained athletes and, where possible, on elite cyclists. To ensure relevance of the information to the conditions likely to be encountered by cyclists, we concentrated our literature survey on studies that have used 2- to 4-week exposures to moderate altitude (1500 to 3000 m). With acclimatisation there is strong evidence of decreased production or increased clearance of lactate in the muscle, moderate evidence of enhanced muscle buffering capacity (beta m) and tenuous evidence of improved mechanical efficiency (ME) of cycling. Our analysis of the relevant literature indicates that, in contrast to the existing paradigm, adaptation to natural or simulated moderate altitude does not stimulate red cell production sufficiently to increase red cell volume (RCV) and haemoglobin mass (Hb(mass)). Hypoxia does increase serum erthyropoietin levels but the next step in the erythropoietic cascade is not clearly established; there is only weak evidence of an increase in young red blood cells (reticulocytes). Moreover, the collective evidence from studies of highly-trained athletes indicates that adaptation to hypoxia is unlikely to enhance sea level VO2max. Such enhancement would be expected if RCV and Hb(mass) were elevated. The accumulated results of 5 different research groups that have used controlled study designs indicate that continuous living and training at moderate altitude does not improve sea level performance of high level athletes. However, recent studies from 3 independent laboratories have consistently shown small improvements after living in hypoxia and training near sea level. While other research groups have attributed the improved performance to increased RCV and VO2max, we cite evidence that changes at the muscle level (beta m and ME) could be the fundamental mechanism. While living at altitude but training near sea level may be optimal for enhancing the performance of competitive cyclists, much further research is required to confirm its benefit. If this benefit does exist, it probably varies between individuals and averages little more than 1%.