ACE I/D gene polymorphism and aerobic endurance development in response to training in a non-elite female cohort

AIM: The aim of this study was to investigate the association between ACE gene polymorphism and short- and medium-duration aerobic endurance performance improvements in response to the same training regimen in a non-elite female cohort. METHODS: Fifty-five female non-elite Caucasian Turkish athletes trained to enhance running speeds corresponding to 70% and 90% of heart rate reserve (V-HRR70 and V-HRR90 respectively) 30 min running speed performance (V-30min) 3 times per week, for 6 weeks. ACE gene polymorphisms studied by PCR analysis. RESULTS: The distribution of genotypes in the whole cohort was 21.8%, 41.8%, 36.4% for II (n=12), ID (n=23) and DD (n=20), respectively. Subjects with ACE II genotype had significantly higher improvements in V-30min and V-HRR70 than the ACE DD group (P<0.05). However, in HRR90 ACE DD genotype had a better performance enhancement in running speed than others (P<0.05). Endurance improvements in the V-HRR70 and in the V-30min showed a linear trend as II>ID>DD (P<0.05 and P<0.01, respectively) while a linear trend as DD>ID>II (P<0.01) observed in V-HRR90. CONCLUSION: ACE II genotype may related with better improvements in medium duration aerobic endurance performance whilst ACE DD genotype seems to be more advantageous in performance enhancement in shorter duration and higher intensity endurance activities.     

ACE I/D polymorphism and cardiac adaptations in adolescent athletes

PURPOSE: The aim of this cross-sectional study was to determine whether there is a correlation between left ventricular hypertrophy (LVH) and angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism in adolescent athletes. METHODS: Seventy-five competitive soccer players (aged 15 +/- 1.2 yr) and 52 untrained control subjects (aged 15 +/- 1.6 yr) were examined with echocardiography (echo) and bioelectrical impedance analysis. The ACE genotype of all subjects was determined by PCR and correlated with left ventricular mass (LVM) indices. RESULTS: Allele frequencies were comparable between athletes and controls. Body surface area (BSA), fat-free mass (FFM), and all mean echo measurements were significantly greater in athletes than in controls. LVM and LVM indices for both BSA and FFM were all significantly greater in athletes than in controls (LVM 195.3 +/- 32 g vs 165.3 +/- 37.6 g; LVM/BSA 115.5 +/- 18.9 g x mq(-1) vs 95 +/- 18.2 g x mq(-1); LVM/FFM 3.5 +/- 0.5 vs 3 +/- 0.54, P < 0.001 for the three variables). Left ventricular hypertrophy was found in 17 (23%) athletes. There was no correlation between ACE I/D polymorphism and athletes with LVH as the II and DD genotype frequencies were identical (41%). However, in athletes with LVH, the presence of the D allele was associated with a greater LVM index than compared to homozygous II genotype (LVM = 145 +/- 7.6 g x mq(-1) in DD+ID group vs 135 +/- 2.9 g x mq(-1) in II group, P = 0.008). CONCLUSIONS: The results of the study show that significant changes occur in cardiac morphology and function in adolescent athletes. Interestingly, the ACE I/D polymorphism was associated with the degree of cardiac hypertrophy but not with the occurrence of LVH itself.     

ACE ID genotype and the muscle strength and size response to unilateral resistance training

PURPOSE: To examine associations among the angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism and the response to a 12-wk (2 d.wk) unilateral, upper-arm resistance training (RT) program in the trained (T, nondominant) and untrained (UT, dominant) arms. METHODS: Subjects were 631 (mean+/-SEM, 24.2+/-0.2 yr) white (80%) men (42%) and women (58%). The ACE ID genotype was in Hardy-Weinberg equilibrium with frequencies of 23.1, 46.1, and 30.8% for ACE II, ID, and DD, respectively (chi=1.688, P=0.430). Maximum voluntary contraction (MVC) and one-repetition maximum (1RM) assessed peak elbow flexor muscle strength. Magnetic resonance imaging measured biceps muscle cross-sectional area (CSA). Multiple variable and repeated-measures ANCOVA tested whether muscle strength and size differed at baseline and pre- to post-RT among T and UT and ACE ID genotype. RESULTS: Baseline muscle strength and size were greater in UT than T (P<0.001) and did not differ among ACE ID genotype in either arm (P >or= 0.05). In T, MVC increases were greater for ACE II/ID (22%) than DD (17%) (P<0.05), whereas 1RM (51%) and CSA (19%) gains were not different among ACE ID genotype pre- to post-RT (P >or= 0.05). In UT, MVC increased among ACE II/ID (7%) (P<0.001) but was similar among ACE DD (2%) pre- to post-RT (P >or= 0.05). In UT, 1RM (11%) and CSA (2%) increases were greater for ACE DD/ID than ACE II (1RM, 7%; CSA, -0.1%) (P<0.05). ACE ID genotype explained approximately 1% of the MVC response to RT in T and approximately 2% of MVC, 2% of 1RM, and 4% of CSA response in UT (P<0.05). CONCLUSION: ACE ID genotype is associated with the contralateral effects of unilateral RT, perhaps more so than with the muscle strength and size adaptations that result from RT.     

中国优秀马拉松运动员ACE基因I/D多态性频率分布特征

通过分析中国马拉松运动员ACE基因I/D多态频率分布特征,探讨其作为杰出耐力基因标记的可行性。选择我国马拉松健将、国际健将级运动员26名作为马拉松运动员组,汉族学生216名作为对照组。对两组受试者进行ACE基因I/D多态性测定。结果显示:我国马拉松运动员组的等位基因频率和基因型频率与对照组比较无显著差异,其中15名国际健将中无一DD型纯合子,提示我国优秀马拉松运动员的纯合子DD型频率低下是其ACE基因多态频率分布的主要特征。     

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.     

飞行员血管紧张素转换酶基因插入/缺失多态性及其血清水平的研究

目的了解飞行员血管紧张素转换酶(ACE)基因插入/缺失（I/D）多态性及其血清水平,探讨ACE基因多态性与飞行员耐力可能的关系。方法飞行员118例,健康对照者96例,用聚合酶链反应（PCR）扩增技术检测ACE基因I/D多态性,用比色法测定血清ACE水平。结果位于ACE基因第16内含子的I/D多态性经PCR扩增后呈三种基因型纯合子插入型（II）、纯合子缺失型（DD）和杂合子插入/缺失型（I/D）。飞行员组II基因型（44.07%）和Ⅰ等位基因频率（0.65）显著高于健康对照组(分别为31.25%和0.52)。ACE基因多态性与血清ACE水平明显相关(DD>ID,DD>II)。结论ACEⅠ基因有可能在飞行员的飞行耐力中起重要作用。     

The ACE gene and endurance performance during the South African Ironman Triathlons

PURPOSE: Several studies have suggested that the insertion (I) variant rather than the deletion (D) variant of the human angiotensin-converting enzyme (ACE) gene is associated with elite endurance performance. The aim of this study was to determine whether the ID polymorphism is associated with the performance of the fastest finishers of the South African Ironman Triathlons. METHODS: A total of 447 Caucasian male triathletes of a variety of nationalities and athletic ability who completed either the 2000 or 2001 South African Ironman Triathlons and 199 Caucasian male control subjects were genotyped for the ACE ID polymorphism. RESULTS: There was a significantly higher frequency of the I allele in the fastest 100 South African-born finishers (103 I, 51.5% and 97 D, 48.5%) compared with the 166 South African-born control subjects (140 I, 42.2% and 192 D, 57.8%) (P = 0.036). There was also a significant linear trend for the allele distribution among the fastest 100 finishers (I allele = 51.5%), slowest 100 finishers (I allele = 47.5%), and control (I allele = 42.2%) South African-born subjects (P = 0.033). There was, however, no significant difference in the ACE genotype or allele frequencies when athletes born outside South Africa were analyzed. CONCLUSION: To our knowledge this is the first study that has examined the effect of an athlete's ACE genotype on their actual performance during an ultra-endurance race. The I allele of the ACE gene was associated with the endurance performance of the fastest 100 South African-born finishers in these triathlons.     

Intermittent hypobaric hypoxia stimulates erythropoiesis and improves aerobic capacity

PURPOSE: The purpose of the study was to examine the effect of a very short intermittent exposure to moderate hypoxia in a hypobaric chamber on aerobic performance capacity at sea level and the erythropoietic response. The effects of hypobaric hypoxia alone and combined with low-intensity exercise were also compared. METHODS: Seventeen members of three high-altitude expeditions were exposed to intermittent hypoxia in a hypobaric chamber over 9 d at simulated altitude, which was progressively increased from 4000 to 5500 m in sessions ranging from 3 to 5 h x d(-1). One group (N = 7; HE group) combined passive exposure to hypoxia with low-intensity exercise on a cycle ergometer. Another group (N = 10; H group) was only exposed to passive hypoxia. Before and after the exposure to hypoxia, medical status, performance capacity, and complete hematological and hemorheological profile of subjects were evaluated. RESULTS: No significant differences were observed between the two groups (HE vs H) in any of the parameters studied, indicating that hypoxia alone was responsible for the changes. After the acclimation period, a significant increase in exercise time (mean difference: +3.9%; P < 0.01), and maximal pulmonary ventilation (+5.5%; P < 0.05) was observed during the maximal incremental test at sea level. Individual lactate-velocity curves significantly shifted to the right (P < 0.05), thus revealing an improvement of aerobic endurance. A significant increase was found in PCV (42.1-45.1%; P < 0.0001), RBC count (5.16 to 5.79 x 10(6) x mm(-3); P < 0.0001), reticulocytes (0.5 to 1.1%; P < 0.0001) and hemoglobin (Hb) concentration (14.2 to 16.7 g x dL(-1); P < 0.002). CONCLUSIONS: It was concluded that short-term hypobaric hypoxia can activate the erythropoietic response and improve the aerobic performance capacity in healthy subjects.     

Is there an association between ACE and CKMM polymorphisms and cycling performance status during 3-week races?

In this paper, we examine the association between polymorphisms of the angiotensin-converting enzyme (ACE) and muscle-specific creatine kinase (CKMM) genes, and the actual performance status observed in professional cyclists capable of completing a classic tour stage race such as the Giro d'Italia, Tour de France, or Vuelta a Espa?a. To accomplish this, we compared the frequencies of the ACE and CKMM genotypes/alleles in 50 top-level Spanish professional cyclists that have completed at least one of these events to 119 sedentary controls, and 27 elite (Olympic-class) Spanish runners. The genetic polymorphism at the CK-MM locus was detected with the NcoI restriction endonuclease. The results of our study showed that the proportion of the DD genotype was higher in cyclists (50.0 %) than in the other two groups (p<0.05), the proportion of the ID genotype was higher in controls (46.2 %) than in the other two groups (p<0.05), and the proportion of the II genotype was higher in runners (40.7 %) than in the other two groups (p<0.05). The proportion of the D allele was higher in both cyclists (65.0 %) and controls (57.6 %) than in runners (46.3 %) (p<0.001), whereas the proportion of the I allele was higher in runners than in the other two groups (p<0.001). No statistical differences were found for CKK-MM- NcoI. We conclude that in top-level professional cyclists capable of completing a classic 3-wk tour race, the frequency distribution of the D allele and the DD genotype seems to be higher than in other endurance athletes such as elite runners (in whom the I allele is especially frequent).     

Variability in hemoglobin mass response to altitude training camps

The present study investigated whether athletes can be classified as responders or non‐responders based on their individual change in total hemoglobin mass (tHb‐mass) following altitude training while also identifying the potential factors that may affect responsiveness to altitude exposure. Measurements were completed with 59 elite endurance athletes who participated in national team altitude training camps. Fifteen athletes participated in the altitude training camp at least twice. Total Hb‐mass using a CO rebreathing method and other blood markers were measured before and after a total of 82 altitude training camps (1350‐2500 m) in 59 athletes. In 46 (56%) altitude training camps, tHb‐mass increased. The amount of positive responses increased to 65% when only camps above 2000 m were considered. From the fifteen athletes who participated in altitude training camps at least twice, 27% always had positive tHb‐mass responses, 13% only negative responses, and 60% both positive and negative responses. Logistic regression analysis showed that altitude was the most significant factor explaining positive tHb‐mass response. Furthermore, male athletes had greater tHb‐mass response than female athletes. In endurance athletes, tHb‐mass is likely to increase after altitude training given that hypoxic stimulus is appropriate. However, great inter‐ and intra‐individual variability in tHb‐mass response does not support classification of an athlete permanently as a responder or non‐responder. This variability warrants efforts to control numerous factors affecting an athlete's response to each altitude training camp.     

No association between ACE I/D polymorphism and cardiovascular hemodynamics during exercise in young women

The ACE I/D polymorphism has been shown to interact with habitual physical activity levels in postmenopausal women to associate with submaximal and with maximal exercise hemodynamics. This investigation was designed to assess the potential relationships between ACE genotype and oxygen consumption (VO2), cardiac output (Q), stroke volume (SV), heart rate (HR), blood pressure (BP), total peripheral resistance (TPR), and arteriovenous oxygen difference ([a-v]O2 diff) during submaximal and maximal exercise in young sedentary and endurance-trained women. Seventy-seven 18-35-yr-old women underwent a maximal exercise test and a number of cardiac output tests on a treadmill using the acetylene rebreathing technique. ACE genotype was not significantly associated with VO2max (II 41.4+/-1.2, ID 39.8+/-0.9, DD 39.8+/-1.1 ml/kg/min, p=ns) or maximal HR (II 191+/-2, ID 191+/-1, DD 193+/-2 bpm, p=ns). In addition, systolic and diastolic BP, (a-v)O2 diff, TPR, SV, and Q during maximal exercise were not significantly associated with ACE genotype. During submaximal exercise, SBP, Q, SV, HR, TPR, and (a-v)O2 diff were not significantly associated with ACE genotype. However, the association between diastolic BP during submaximal exercise and ACE genotype approached significance (p=0.08). In addition, there were no statistically significant interactions between ACE genotype and habitual physical activity (PA) levels for any of the submaximal or the maximal exercise hemodynamic variables. We conclude that the ACE I/D polymorphism was not associated, independently or interacting with habitual PA levels, submaximal, or maximal cardiovascular hemodynamics in young women.     

Red blood cell profile of elite olympic distance triathletes. A three-year follow-up

The purpose of this study was to monitor general and individual changes in hematological variables during long-term endurance training, detraining and altitude training in elite Olympic distance triathletes. Over a period of three years, a total of 102 blood samples were collected in eleven (7-male and 4 female) elite Olympic distance triathletes (mean +/- SD; age = 26.4 +/- 5.1 yr; VO(2) max = 67.9 +/- 6.6 ml/min/kg) for determination of hemoglobin (Hb), hematocrit (Hct), red blood cell count (RBC), Mean corpuscular hemoglobin (MCH), Mean corpuscular hemoglobin content (MCHC), Mean corpuscular volume (MCV) and plasma ferritin. The data were pooled and divided into three periods; off-season, training season and race season. Blood samples obtained before and after altitude training were analyzed separately. Of all measured variables only RBC showed a significant decrease (p < 0.05) during the race season compared to the training season. Hematological values below the lower limit of the normal range were found in 46 % of the athletes during the off-season. This percentage increased from 55 % during the training season to 72 % of the athletes during the race season. Hemoglobin and ferritin values were most frequently below the normal range. There was a weak correlation between Hb levels and VO(2) max obtained during maximal cycling (r = 0.084) and running (r = 0.137) tests. Unlike training at 1500 m and 1850 m, training at an altitude of 2600 m for three weeks showed significant increases in Hb (+ 10 %; p < 0.05), Hct (+ 11 %; p < 0.05) and MCV (+ 5 %; p < 0.05). Long-term endurance training does not largely alter hematological status. However, regular screening of hematological variables is desirable as many athletes have values near or below the lower limit of the normal range. The data obtained from altitude training suggest that a minimum altitude (>2000 m) is necessary to alter hematological status.     

Current trends in altitude training

Recently, endurance athletes have used several novel approaches and modalities for altitude training including: (i) normobaric hypoxia via nitrogen dilution (hypoxic apartment); (ii) supplemental oxygen; (iii) hypoxic sleeping devices; and (iv) intermittent hypoxic exposure (IHE). A normobaric hypoxic apartment simulates an altitude environment equivalent to approximately 2000 to 3000m (6560 to 9840ft). Athletes who use a hypoxic apartment typically 'live and sleep high' in the hypoxic apartment for 8 to 18 hours a day, but complete their training at sea level, or approximate sea level conditions. Several studies suggest that using a hypoxic apartment in this manner produces beneficial changes in serum erythropoietin (EPO) levels, reticulocyte count and red blood cell (RBC) mass, which in turn may lead to improvements in postaltitude endurance performance. However, other studies failed to demonstrate significant changes in haematological indices as a result of using a hypoxic apartment. These discrepancies may be caused by differences in methodology, the hypoxic stimulus that athletes were exposed to and/or the training status of the athletes. Supplemental oxygen is used to simulate either normoxic (sea level) or hyperoxic conditions during high-intensity workouts at altitude. This method is a modification of the 'high-low' strategy, since athletes live in a natural terrestrial altitude environment but train at 'sea level' with the aid of supplemental oxygen. Limited data regarding the efficacy of hyperoxic training suggests that high-intensity workouts at moderate altitude (1860m/6100ft) and endurance perfor- mance at sea level may be enhanced when supplemental oxygen training is utilised at altitude over a duration of several weeks. Hypoxic sleeping devices include the Colorado Altitude Training (CAT) Hatch (hypobaric chamber) and Hypoxico Tent System (normobaric hypoxic system), both of which are designed to allow athletes to sleep high and train low. These devices simulate altitudes up to approximately 4575 m/15006 ft and 4270 m/14005 ft, respectively. Currently, no studies have been published on the efficacy of these devices on RBC production, maximal oxygen uptake and/or performance in elite athletes. IHE is based on the assumption that brief exposures to hypoxia (1.5 to 2.0 hours) are sufficient to stimulate the release of EPO, and ultimately bring about an increase in RBC concentration. Athletes typically use IHE while at rest, or in conjunction with a training session. Data regarding the effect of IHE on haematological indices and athletic performance are minimal and inconclusive.     

血管紧张素转换酶基因多态性与房颤心肌纤维化的相关性研究

目的：研究血管紧张素转换酶基因（ACE）插入／缺失多态性与心肌纤维化及心房纤颤的相关性，以寻找心房纤颤发病的分子机制。方法：选择50例房颤患者（房颤组）及43例非房颤者（对照组），用PCR方法检测两组ACE基因插入／缺失多态性；用ELISA法测定心肌纤维化的指标（Ⅰ型前胶原羧基端肽、Ⅲ型前胶原氨基端肽）．比较不同基因型、不同等位基因的分布及Ⅰ型前胶原羧基端肽（PIP）和Ⅲ型前胶原氨基端肽（PⅢP）的血清浓度。结果：房颤组与对照组ACEI／D多态性缺失纯合型（DD型）、杂合子（DⅠ型）、插入纯合型（Ⅱ型）基因型频率分别为34％、40％、26％和18．6％、41．9％、39．5％；房颤组与对照组D等位基因、Ⅰ等位基因分布频率为54％、46％和39．5％、60．5％；对不同基因型分布比较发现：D等位基因分布频率在房颤组中较对照组明显增大（P〈0．05）；房颤组PIP、PⅢP浓度明显高于对照组（P〈0．05）；在不同基因型之间PIP、PⅢP浓度比较中发现，DD基因型PIP、PⅢP浓度显著高于DⅠ型和Ⅱ型（P〈0．05）。结论：D等位基因可能是房颤的易患基因；房颤患者心肌纤维化指标PIP、PⅢP显著升高；ACEDD基因型可能是心肌纤维化及心脏重构的危险因素。     

Angiotensin-converting enzyme genotype and successful ascent to extreme high altitude

Interindividual variation in acclimatization to altitude suggests a genetic component, and several candidate genes have been proposed. One such candidate is a polymorphism in the angiotensin converting enzyme (ACE) gene, where the insertion (I-allele), rather than the deletion (D-allele), of a 287 base pair sequence has been associated with lower circulating and tissue ACE activity and has a greater than normal frequency among elite endurance athletes and, in a single study, among elite high altitude mountaineers. We tested the hypothesis that the I-allele is associated with successful ascent to the extreme high altitude of 8000 m. 141 mountaineers who had participated in expeditions attempting to climb an 8000-m peak completed a questionnaire and provided a buccal swab for ACE I/D genotyping. ACE genotype was determined in 139 mountaineers. ACE genotype distribution differed significantly between those who had successfully climbed beyond 8000 m and those who had not (p = 0.003), with a relative overrepresentation of the I-allele among the successful group (0.55 vs. 0.36 in successful vs. unsuccessful, respectively). The I-allele was associated with increased maximum altitudes achieved: 8079 +/- 947 m for DDs, 8107 +/- 653 m for IDs, and 8559 +/- 565 m for IIs (p = 0.007). There was no statistical difference in ACE genotype frequency between those who climbed to over 8000 m using supplementary oxygen and those who did not (p = 0.267). This study demonstrates an association between the ACE I-allele and successful ascent to over 8000 m.     

Interaction between angiotensin converting enzyme insertion/deletion genotype and exercise training on knee extensor strength in older individuals

Prior data in young individuals suggest that the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism interacts with exercise to affect athletic performance, but the direction of the genotype effect depends on the outcome assessed (endurance vs. strength). The purpose of this study was to determine whether the ACE I/D genotype influences physical function responses to exercise training in older individuals. Physical function (muscle strength, walking distance, and self-reported disability) was measured before and after an 18-month randomized, controlled exercise trial in 213 older (>or= 60 yrs), obese (BMI >or= 28 kg/m2) men and women. Exercise training consisted of walking and light weight lifting for one hour 3 times/wk. At baseline, there were no associations between ACE I/D genotype and measures of physical function. Following exercise training, individuals with the DD genotype showed greater gains in knee extensor strength compared to II individuals. There was a significant (p = 0.014) interaction between ACE I/D genotype and exercise treatment on percent change in knee strength. In addition, there was a trend towards a greater improvement in physical disability score in DD genotypes (p = 0.13), but changes in 6-minute walk distance were not different between genotype groups. Thus, changes in muscle strength with exercise training in older individuals may be dependent on ACE I/D genotype.     

ACE genotype and the muscle hypertrophic and strength responses to strength training

PURPOSE: Previous studies have linked an insertion/deletion polymorphism in the angiotensin-converting enzyme (ACE) gene with variability in muscle strength responses to strength training (ST), though conclusions have been inconsistent across investigations. Moreover, most previous studies have not investigated the influence of sex on the association of ACE I/D genotype with muscle phenotypes. The purpose of this study was to investigate the association of ACE genotype with muscle phenotypes before and after ST in older men and women. METHODS: Eighty-six inactive men and 139 inactive women, ages 50-85 yr (mean: 62 yr), were studied before and after 10 wk of unilateral knee extensor ST. The one-repetition maximum (1RM) test was used to assess knee extensor muscle strength, and computed tomography was used to measure quadriceps muscle volume (MV). Differences were compared among ACE genotype groups (II vs ID vs DD). RESULTS: Across the entire cohort at baseline, ACE genotype was significantly associated with total lean mass and body weight, with higher values in DD genotype carriers (both P < 0.05). At baseline, DD genotype carriers exhibited significantly greater MV compared with II genotype carriers for both the trained leg (men: 1828 +/- 44 vs 1629 +/- 70; women: 1299 +/- 34 vs 1233 +/- 49; P = 0.02) and untrained leg (men: 1801 +/- 46 vs 1559 +/- 72; women: 1268 +/- 36 vs 1189 +/- 51; P = 0.01), with no significant genotype x sex interaction. No ACE genotype associations were observed for the 1RM or MV adaptations to ST in either men or women. CONCLUSIONS: In the present study, ACE genotype was associated with baseline differences in muscle volume, but it was not associated with the muscle hypertrophic response to ST.     

平原人进驻高原后红细胞生成素的变化

目的　探讨红细胞生成素在高原低氧适应机制中的作用。方法　对平原进驻海拔 3 70 0m和气 5 3 80m第 7天及半年的健康青年进行血液促红细胞生成素 (EPO)、血红蛋白 (Hb)及血氧饱和度 (SaO2 )检测 ,并与平原健康青年作对照。结果　进驻高原低氧环境EPO、Hb较平原增高显著 (P <0 .0 5或 0 .0 1 ) ,SaO2 降低非常显著 (P <0 .0 1 )。进驻高原第 7天和半年 ,3 70 0m较 5 3 80mEPO ,Hb降低非常显著 ,SaO2 增高非常显著 (P <0 .0 1 )。进驻 3 70 0m ,第 7天较半年EPO无统计学意义 (P >0 .0 5 ) ,Hb ,SaO2 差异显著 (P <0 .0 5或 0 .0 1 ) ;进驻 5 3 80m ,第 7天较半年EPO ,Hb,SaO2 均有显著性差异 (P <0 .0 5或P <0 .0 1 )。结论　在高原缺氧环境下 ,红细胞生成素调节机制紊乱 ,是导致继发性红细胞增多的一个重要环节。     

Individual variation in the erythropoietic response to altitude training in elite junior swimmers

Objectives: Inter-individual variations in sea level performance after altitude training have been attributed, at least in part, to an inter-individual variability in hypoxia induced erythropoiesis. The aim of the present study was to examine whether the variability in the increase in total haemoglobin mass after training at moderate altitude could be predicted by the erythropoietin response after 4 h exposure to normobaric hypoxia at an ambient Po₂ corresponding to the training altitude.

Methods: Erythropoietin levels were measured in 16 elite junior swimmers before and after 4 h exposure to normobaric hypoxia (Fio₂ 0.15, ~2500 m) as well as repeatedly during 3 week altitude training (2100–2300 m). Before and after the altitude training, total haemoglobin mass (CO rebreathing) and performance in a stepwise increasing swimming test were determined.

Results: The erythropoietin increase (10–185%) after 4 h exposure to normobaric hypoxia showed considerable inter-individual variation and was significantly (p<0.001) correlated with the acute erythropoietin increase during altitude training but not with the change in total haemoglobin mass (significant increase of ~6% on average). The change in sea level performance after altitude training was not related to the change in total haemoglobin mass.

Conclusions: The results of the present prospective study confirmed the wide inter-individual variability in erythropoietic response to altitude training in elite athletes. However, their erythropoietin response to acute altitude exposure might not identify those athletes who respond to altitude training with an increase in total haemoglobin mass.

     

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).