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Hypoxic dose, intensity distribution and fatigue monitoring are paramount for "live high-train low" effectiveness
... Pre-altitude camp screening for iron status [30], and the hypoxic sensitivity of parameters such as erythropoietin (EPO), arterial oxygen saturation (SaO 2 ), ventilation and training ability under hypoxic conditions [14], may be useful to guide individual acclimatisation to altitude, and manage the absolute and relative training intensity distribution [12]. Hypoxic sensitivity, or tolerance, has been studied in high altitude mountaineering, finding parameters such as a lower hypoxic ventilatory response (HVR) and greater decrease in SaO 2 are good predictors of acute mountain sickness (AMS) susceptibility [13,55]. ...
... It has been suggested that adequately designed and controlled training loads, and continuously monitoring an individual athlete's adaptation and health status may result in a more consistent positive adaptive response [12,49,73]. A primary aim of the present training camp was to observe responses of high performance athletes, which created some specific challenges. ...
... Furthermore, we observed responses to one altitude training camp, whereas most endurance programmes now commit monitoring the long-term effects of accumulated altitude training through repeated exposures [48,77]. Further investigation should examine the changes in haematology and endurance performance during the entire season, paying particular attention to the athletes training load and how this influences the resultant adaptations [12,73]. ...
PurposeElite endurance runners frequently utilise live high-train high (LHTH) altitude training to improve endurance performance 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 VO2max 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.ResultsA difference (P < 0.05) was found from PRE to POST in average tHbmass (1.8% ± 3.4%), VO2max (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 (ΔSpr) 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 VO2max.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 VO2max. HST prior to LHTH could allow coaches and practitioners to better inform the acclimatisation strategies and training load application of endurance runners at altitude.
... Combined hematological and nonhematological responses can result in increased maximal oxygen uptake ( V O 2max ) and/or competition performance at sea level [11], although conflicting views still remain, particularly with regards to LHTL [12,13]. Several factors impact upon altitude adaptation, such as the duration and degree of hypoxic exposure, absolute and relative intensity of training and its distribution, iron availability, injury/ illness status, and inter-individual variability [14][15][16][17][18][19][20][21]. Both female and male elite athletes often show progressive increments in Hb mass at increasing altitudes from 1360 to 2100 and 2320 m [22][23][24]. ...
... Conversely, illness and/or injury could inhibit altitude adaptations [22,[25][26][27] and the stress of altitude training may increase the risk of illness [28]. Therefore, poorly planned training programs may sometimes result in deleterious outcomes, such as underperformance, excessive fatigue, overtraining, illness, and/or injury [21,29]. ...
... Some of the most popular altitude training locations in the world feature the possibility, within a ~ 1 h drive, to also carry out selected high-intensity training sessions closer to sea level (e.g., Flagstaff, AZ, USA; St. Moritz, Switzerland; Sierra Nevada, Spain). The hypoxic conditions encountered at altitude may indirectly impose a more polarized training intensity distribution, with a strong focus on low-intensity, long-duration training, in combination with fewer high-intensity training bouts [21]. Interestingly, such training intensity distribution is widely considered best practice to optimize adaptations and performance in elite endurance athletes [55,56]. ...
Since the 1960s there has been an escalation in the purposeful utilization of altitude to enhance endurance athletic performance. This has been mirrored by a parallel intensification in research pursuits to elucidate hypoxia-induced adaptive mechanisms and substantiate optimal altitude protocols (e.g., hypoxic dose, duration, timing, and confounding factors such as training load periodization, health status, individual response, and nutritional considerations). The majority of the research and the field-based rationale for altitude has focused on hematological outcomes, where hypoxia causes an increased erythropoietic response resulting in augmented hemoglobin mass. Hypoxia-induced non-hematological adaptations, such as mitochondrial gene expression and enhanced muscle buffering capacity may also impact athletic performance, but research in elite endurance athletes is limited. However, despite significant scientific progress in our understanding of hypobaric hypoxia (natural altitude) and normobaric hypoxia (simulated altitude), elite endurance athletes and coaches still tend to be trailblazers at the coal face of cutting-edge altitude application to optimize individual performance, and they already implement novel altitude training interventions and progressive periodization and monitoring approaches. Published and field-based data strongly suggest that altitude training in elite endurance athletes should follow a long- and short-term periodized approach, integrating exercise training and recovery manipulation, performance peaking, adaptation monitoring, nutritional approaches, and the use of normobaric hypoxia in conjunction with terrestrial altitude. Future research should focus on the long-term effects of accumulated altitude training through repeated exposures, the interactions between altitude and other components of a periodized approach to elite athletic preparation, and the time course of non-hematological hypoxic adaptation and de-adaptation, and the potential differences in exercise-induced altitude adaptations between different modes of exercise.
... During the first days of hypoxic exposure, some detrimental effects can occur such as a decrease in maximal oxygen consumption, requiring to appropriately reduce and manage training loads (Brocherie et al., 2015;Brocherie, Schmitt, & Millet, 2017;Issurin, 2010). Several studies have shown a large interindividual variability in the physiological responses to prolonged hypoxic exposure associated with training (Chapman, Stray-Gundersen, & Levine 1998;Millet, Roels, Schmitt, Woorons, & Richalet, 2010) Changes in some physiological variables (i.e., an increase in ventilatory response; Boron & Boulpaep, 2012, a decrease in plasma volume; Sawka, Convertino, Eichner, Schnieder, & Young, 2000, or an increase in erythropoietin production; Lundby et al., 2007) may differ between athletes after few days of training in hypoxia. ...
... Overall, the response to the hypoxic exercise test is indicative of performance responses and tolerance at moderate altitude. Although careful monitoring of training load is important during altitude acclimatization (Brocherie et al., 2015(Brocherie et al., , 2017Issurin, 2010), this highlights the particular attention that must be carried on athletes sensitive to hypoxic stress. ...
Purpose:
The hypoxic exercise test is used to predict the susceptibility to severe High Altitude Illness (SHAI). In the present study, we aimed to use this test to predict the changes in performance and the physiological responses to moderate altitude in elite swimmers.
Methods:
Eighteen elite swimmers performed a hypoxic exercise test at sea level before a moderate 12-day altitude training camp (1,850 m) to determine if they were susceptible or not to SHAI. A maximal swimming performance test was conducted before (at sea level), during (at 1,850 m), and after (at sea level) the intervention. Arterial oxygen saturation (pulse oximetry), Lake Louise score, and quality of sleep questionnaire were collected every morning. The participants were classified in two groups, those who had a moderate to high risk of SHAI (SHAIscore ≥ 3) and those who had a low risk of SHAI (SHAIscore < 3).
Results:
Seven swimmers presented a high risk of SHAI including three of them with a SHAIscore > 5. Pearson correlations indicated that SHAIscore was strongly correlated with the decrease in swimming performance at altitude (r = .60, p < .01). Arterial oxygen saturation during the hypoxic exercise test was the physiological variable that was best related to performance decrease at altitude (r = .54, p < .05). No differences were observed for Lake Louise score and quality of sleep between swimmers who suffered from SHAI or not (p > .1).
Conclusion:
In a population of elite swimmers, the combination of clinical and physiological variables (SHAIscore , oxygen desaturation) estimated the performance decrease at moderate altitude. The hypoxic exercise test could allow coaches and scientists to better determine the individual response of their athletes and manage the altitude acclimatization.
... Frontiers in Physiology frontiersin.org continuity (Brocherie et al., 2017;Mujika et al., 2018). Thus, to minimize this potential risk and maximize the benefits of AT, an effective health and load monitoring system should be developed (Sperlich et al., 2016;Schmitt et al., 2018;Mujika et al., 2019) and adequate nutritional support should be provided (Govus et al., 2015;Stellingwerff et al., 2019). ...
Objective: This study aimed to compare and rank the effect of hypoxic practices on maximum oxygen consumption (VO2max) in athletes and determine the hypoxic dose-response correlation using network meta-analysis.
Methods: The Web of Science, PubMed, EMBASE, and EBSCO databases were systematically search for randomized controlled trials on the effect of hypoxc interventions on the VO2max of athletes published from inception until 21 February 2023. Studies that used live-high train-high (LHTH), live-high train-low (LHTL), live-high, train-high/low (HHL), intermittent hypoxic training (IHT), and intermittent hypoxic exposure (IHE) interventions were primarily included. LHTL was further defined according to the type of hypoxic environment (natural and simulated) and the altitude of the training site (low altitude and sea level). A meta-analysis was conducted to determine the standardized mean difference between the effects of various hypoxic interventions on VO2max and dose-response correlation. Furthermore, the hypoxic dosage of the different interventions were coordinated using the “kilometer hour” model.
Results: From 2,072 originally identified titles, 59 studies were finally included in this study. After data pooling, LHTL, LHTH, and IHT outperformed normoxic training in improving the VO2max of athletes. According to the P-scores, LHTL combined with low altitude training was the most effective intervention for improving VO2max (natural: 0.92 and simulated: 0.86) and was better than LHTL combined with sea level training (0.56). A reasonable hypoxic dose range for LHTH (470–1,130 kmh) and HL (500–1,415 kmh) was reported with an inverted U-shaped curve relationship.
Conclusion: Different types of hypoxic training compared with normoxic training serve as significant approaches for improving aerobic capacity in athletes. Regardless of the type of hypoxic training and the residential condition, LHTL with low altitude training was the most effective intervention. The characteristics of the dose-effect correlation of LHTH and LHTL may be associated with the negative effects of chronic hypoxia.
... In addition to individual hematological responses, changes in TTE and VO 2max varied significantly between the participants regardless of the magnitude in their Hb mass changes. Consequently, the management of total stress and training quality may have been factors affecting performance changes 39 and should be prioritized when planning the implementation of training camps and training, in general. ...
Purpose
To investigate whether 4 weeks of normobaric “live high–train low and high” (LHTLH) causes different hematological, cardiorespiratory, and sea‐level performance changes compared to living and training in normoxia during a preparation season.
Methods
Nineteen (13 women, 6 men) cross‐country skiers competing at the national or international level completed a 28‐day period (∼18 h day⁻¹) of LHTLH in normobaric hypoxia of ∼2400 m (LHTLH group) including two 1 h low‐intensity training sessions per week in normobaric hypoxia of 2500 m while continuing their normal training program in normoxia. Hemoglobin mass (Hbmass) was assessed using a carbon monoxide rebreathing method. Time to exhaustion (TTE) and maximal oxygen uptake (VO2max) were measured using an incremental treadmill test. Measurements were completed at baseline and within 3 days after LHTLH. The control group skiers (CON) (seven women, eight men) performed the same tests while living and training in normoxia with ∼4 weeks between the tests.
Results
Hbmass in LHTLH increased 4.2 ± 1.7% from 772 ± 213 g (11.7 ± 1.4 g kg⁻¹) to 805 ± 226 g (12.5 ± 1.6 g kg⁻¹) (p < 0.001) while it was unchanged in CON (p = 0.21). TTE improved during the study regardless of the group (3.3 ± 3.4% in LHTLH; 4.3 ± 4.8% in CON, p < 0.001). VO2max did not increase in LHTLH (61.2 ± 8.7 mL kg⁻¹ min⁻¹ vs. 62.1 ± 7.6 mL kg⁻¹ min⁻¹, p = 0.36) while a significant increase was detected in CON (61.3 ± 8.0–64.0 ± 8.1 mL kg⁻¹ min⁻¹, p < 0.001).
Conclusions
Four‐week normobaric LHTLH was beneficial for increasing Hbmass but did not support the short‐term development of maximal endurance performance and VO2max when compared to the athletes who lived and trained in normoxia.
... Given the cumulative efects of hypoxic exposure and exercise on immune function, the authors proposed a model whereby an increased training load exacerbated by hypoxia may decrease glutamine below the physiological range, thus increasing the risk of infection [4]. The control and modulation of training load at altitude is important for maintaining the immune status of athletes, as well as to facilitate training adaptations, and suggests the need for close monitoring of training load and wellness at altitude [13,108]. Indeed, overtraining symptoms (e.g. ...
Live high train high (LHTH) is the original method of altitude training used by elite athletes to enhance sea-level performance. 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 erythropoiesis 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.
... First, the choice of the articles inserted in a systematic review or a meta-analysis is paramount because the main purpose is to draw valid conclusion only from a comprehensive data set and not from a "cherry-picked" one. Two of the three self-called "well-controlled conducted normobaric LHTL studies" supporting the view of the authors (1) should be interpreted with caution because latent drawbacks have been previously pinpointed (3,4,5). The common limit between these studies relies on inadequate training prescription in the LHTL groups, which may have participated to physical or mental fatigue development (with possible expansion to overreaching/overtraining), thereby hampering time trial performance. ...
To assess how altitude training impacts force-velocity-power (F-V-P) profiling and muscular power and anaerobic capacity in elite badminton players in reference to intra- and inter-individual sex-based variability. Following a quasi-experimental design, 14 players (6 females, 8 males) from the French national badminton singles and doubles teams performed a 3-week ‘living high-training high’ camp at natural altitude (2320 m). F-V-P profile and Wingate anaerobic test were assessed Pre- and Post-intervention, using ANOVA repeated measures conventional statistics, with further estimation statistics to show the magnitude of the testing condition and visualize intra- and inter-individual responses. No significant interaction nor time effect (Pre- vs. Post-) was observed for any variables (all p > 0.05), but a significant sex effect was observed for maximal theoretical velocity (p < 0.01), relative maximal theoretical power (Pmaxrel) (p = 0.02) and relative F-V-P profile and for peak and mean power outputs (both p < 0.001) during Wingate test. Pre-to-Post changes (from −11.0% to + 14.4%) did not significantly differ between sexes, except for Pmaxrel (p < 0.05) in favor of female athletes (+10.2% vs. −4.3% for male athletes). Hedge’s g effect sizes (male minus female) revealed moderate and large effects for F-V-P profiling-derived variables. Mean conventional statistics did not reveal significant effect of altitude training, mainly due to high intra- and inter-variability across F-V-P profiling-derived variables and Wingate test. Substantial sex-based difference contributes to this variability, emphasizing the importance of individualized approach to enhance participant responsiveness to altitude training.
The aim was to investigate whether 6 weeks of normobaric “Live High-Train Low” (LHTL) using altitude tents affect highly trained athletes incremental peak power, 26-km time-trial cycling performance, 3-min all-out performance, and 30-s repeated sprint ability. In a double-blinded, placebo-controlled cross-over design, seven highly trained triathletes were exposed to 6 weeks of normobaric hypoxia (LHTL) and normoxia (placebo) for 8 h/day. LHTL exposure consisted of 2 weeks at 2500 m, 2 weeks at 3000 m, and 2 weeks at 3500 m. Power output during an incremental test, ~26-km time trial, 3-min all-out exercise, and 8 × 30 s of all-out sprint was evaluated before and after the intervention. Following at least 8 weeks of wash-out, the subjects crossed over and repeated the procedure. Incremental peak power output was similar after both interventions [LHTL: 375 ± 74 vs. 369 ± 70 W (pre-vs-post), placebo: 385 ± 60 vs. 364 ± 79 W (pre-vs-post)]. Likewise, mean power output was similar between treatments as well as before and after each intervention for time trial [LHTL: 257 ± 49 vs. 254 ± 54 W (pre-vs-post), placebo: 267 ± 57 vs. 267 ± 52 W (pre-vs-post)], and 3-min all-out [LHTL: 366 ± 68 vs. 369 ± 72 W (pre-vs-post), placebo: 365 ± 66 vs. 355 ± 71 W (pre-vs-post)]. Furthermore, peak- and mean power output during repeated sprint exercise was similar between groups at all time points (n = 5). In conclusion, 6 weeks of normobaric LHTL using altitude tents simulating altitudes of 2500–3500 m conducted in a double-blinded, placebo-controlled cross-over design do not affect power output during an incremental test, a ~26-km time-trial test, or 3-min all-out exercise in highly trained triathletes. Furthermore, 30 s of repeated sprint ability was unaltered.
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Purpose:
To describe training variations across the annual cycle in Olympic and World Champion endurance athletes, and determine whether these athletes used tapering strategies in line with recommendations in the literature.
Methods:
Eleven elite XC skiers and biathletes (4 male; 28±1 yr, 85±5 mL x min(-1) x kg(-1) VO2max, 7 female, 25±4 yr, 73±3 mL x min(-1) x kg(-1) VO2max) reported one year of day-to-day training leading up to the most successful competition of their career. Training data were divided into periodization and peaking phases and distributed into training forms, intensity zones and endurance activity forms.
Results:
Athletes trained ∼800 h/500 sessions x year(-1), including ∼500 h x year(-1) of sport-specific training. Ninety-four percent of all training was executed as aerobic endurance training. Of this, ∼90% was low intensity training (LIT, below the first lactate threshold) and 10% high intensity training (HIT, above the first lactate threshold) by time. Categorically, 23% of training sessions were characterized as HIT with primary portions executed at or above the first lactate turn point. Training volume and specificity distribution conformed to a traditional periodization model, but absolute volume of HIT remained stable across phases. However, HIT training patterns tended to become more polarized in the competition phase. Training volume, frequency and intensity remained unchanged from pre-peaking to peaking period, but there was a 32±15% (P<.01) volume reduction from the preparation period to peaking phase.
Conclusions:
The annual training data for these Olympic and World champion XC skiers and biathletes conforms to previously reported training patterns of elite endurance athletes. During the competition phase, training became more sport-specific, with 92% performed as XC skiing. However, they did not follow suggested tapering practice derived from short-term experimental studies. Only three out of 11 athletes took a rest day during the final 5 days prior to their most successful competition.
Sleeping in a hypoxic environment is becoming increasingly popular among athletes attempting to simulate a "live high, train low" training regime. The purpose of this study was to investigate the acute effects (one night) of sleeping in a normobaric hypoxic tent (NH) (PO(2) = 110 mm Hg approximately 2500 m) upon markers of sleep physiology and quality, compared with sleep in a normal ambient environment (BL) (PO(2) = 159 mm Hg approximately sea level) and sleep in a normobaric normoxic tent (NN) (PO(2) = 159 mm Hg).
Eight male recreational athletes (age 34.5 +/- 6.9 yr; stature 169.1 +/- 8.7 cm; mass 69.3 +/- 8.2 kg; VO(2max) 56.4 +/- 8.3 mL.kg(-1).min(-1)) participated in the study using a randomized, double-blind crossover design. Polysomnographic studies were undertaken to measure sleep stages, arterial oxygen saturation (SpO(2)), heart rate (HR), and the Respiratory Disturbance Index (RDI). The Leeds Sleep Evaluation Questionnaire (LSEQ) was used to measure subjective sleep quality.
NH (89.9 +/- 4.8%) resulted in a significantly lower (P < 0.05) SpO(2) compared with both BL (95.7 +/- 1.5%) and NN (93.5 +/- 4.0%). Heart rate was significantly higher (P < 0.05) in NH (51.5 +/- 7.6 beats.min(-1)) compared with NN (48.3 +/- 6.9 beats.min(-1)) but was similar versus BL (50.3 +/- 4.3 beats.min(-1)). RDI (counts.h) and RDI (total counts) were lowest in BL (3.5 +/- 2.5; 18.1 +/- 7.9) and highest in NH (36.8 +/- 42.7; 221.9 +/- 254.5). The difference in RDI (counts.h(-1) and total counts) between NH and BL was significant (P < 0.05). The LSEQ revealed that subjects' "behavior following waking" score was significantly (P < 0.05) lower in NH (40.9 +/- 9.2) compared with BL (52.3 +/- 8.3).
This study presents evidence that sleep in a normobaric hypoxic tent at a simulated altitude of 2500 m may affect sleep parameters in some individuals. This type of analysis may be useful in the early identification of poorly responding individuals to simulated altitude environments.
The "living high-training low" (LHTL) model is frequently used to enhance aerobic performance. However, the clinical tolerance and acclimatization process to this intermittent exposure needs to be examined. Forty one athletes from three federations (cross-country skiers, n=11; swimmers, n=18; runners, n=12) separately performed a 13 to 18-day training at the altitude of 1,200 m, by sleeping either at 1,200 m (CON) or in hypoxic rooms (HYP), with an O2 fraction corresponding to 2,500 m (5 nights for swimmers and 6 for skiers and runners), 3,000 m (6 nights for skiers, 8 for swimmers and 12 for runners) and 3,500 m (6 nights for skiers). Measurements performed before, 1 or 15 days after training were ventilatory response (HVRe) and desaturation (deltaSaO2e) during hypoxic exercise, an evaluation of cardiac function by echocardiography, and leukocyte count. Lake Louise AMS score and arterial O2 saturation during sleep were measured daily for HYP. Subjects did not develop symptoms of AMS. Mean nocturnal SaO2 decreased with altitude down to 90% at 3,500 m and increased with acclimatization (except at 3,500 m). Leukocyte count was not affected except at 3,500 m. The heart function was not affected by LHTL. Signs of ventilatory acclimatization were present immediately after training (increased HVRe and decreased deltaSaO2e) and had disappeared 15 days later. In conclusion, LHTL was well tolerated and compatible with aerobic training. Comparison of the three patterns of training suggests that a LHTL session should not exceed 3,000 m, for at least 18 days, with a minimum of 12 h day(-1) of exposure.
This study investigated changes in heart rate variability (HRV) in elite Nordic-skiers to characterize different types of "fatigue" in 27 men and 30 women surveyed from 2004 to 2008. R-R intervals were recorded at rest during 8 min supine (SU) followed by 7 min standing (ST). HRV parameters analysed were powers of low (LF), high (HF) frequencies, (LF+HF) (ms(2)) and heart rate (HR, bpm). In the 1 063 HRV tests performed, 172 corresponded to a "fatigue" state and the first were considered for analysis. 4 types of "fatigue" (F) were identified: 1. F(HF(-)LF(-))SU_ST for 42 tests: decrease in LFSU (- 46%), HFSU (- 70%), LFST (- 43%), HFST (- 53%) and increase in HRSU (+ 15%), HRST (+ 14%). 2. F(LF(+) SULF(-) ST) for 8 tests: increase in LFSU (+ 190%) decrease in LFST (- 84%) and increase in HRST (+ 21%). 3. F(HF(-) SUHF(+) ST) for 6 tests: decrease in HFSU (- 72%) and increase in HFST (+ 501%). 4. F(HF(+) SU) for only 1 test with an increase in HFSU (+ 2161%) and decrease in HRSU (- 15%). Supine and standing HRV patterns were independently modified by "fatigue". 4 "fatigue"-shifted HRV patterns were statistically sorted according to differently paired changes in the 2 postures. This characterization might be useful for further understanding autonomic rearrangements in different "fatigue" conditions.
© Georg Thieme Verlag KG Stuttgart · New York.
Chronic living at altitudes ~2500m causes consistent hematological acclimatization in most, but not all, groups of athletes; however, responses of erythropoietin (EPO) and red cell mass to a given altitude show substantial individual variability. We hypothesized that athletes living at higher altitudes would experience greater improvements in sea level performance, secondary to greater hematological acclimatization, compared to athletes living at lower altitudes. After 4 weeks of group sea level training and testing, 48 collegiate distance runners (32M, 16W) were randomly assigned to one of four living altitudes (1780m, 2085m, 2454m, or 2800m). All athletes trained together daily at a common altitude from 1250m - 3000m following a modified Live High - Train Low model. Subjects completed hematological, metabolic, and performance measures at sea level, before and after altitude training; EPO was assessed at various time points while at altitude. Upon return from altitude, 3000m time trial performance was significantly improved in groups living at the middle two altitudes (2085m and 2454m) but not in groups living at 1780m and 2800m. EPO was significantly higher in all groups at 24h and 48h, but returned to sea level baseline after 72h in the 1780m group. Erythrocyte volume was significantly higher within all groups after return from altitude, and was not different between groups. These data suggest that when completing a 4 week altitude camp following the Live High - Train Low model, there is a target altitude between 2000m and 2500m that produces an optimal acclimatization response for sea level performance.