PURPOSE: Determine if a series of trials with fraction of inspired oxygen (FiO2) content deception could improve 4000-m cycling time-trial (TT) performance. METHODS: Fifteen trained male cyclists (mean ± SD: body mass 74.2 ± 8.0 kg; peak oxygen uptake 62 ± 6 mL.kg-1.min-1) completed six, 4000-m cycling TTs in a semi-randomised order. After a familiarisation TT, cyclists were informed in two initial trials they were inspiring normoxic air (NORM, FiO2: 0.21), however in one trial (deception condition) they inspired hyperoxic air (NORM-DEC, FiO2: 0.36). During two subsequent TTs, cyclists were informed they were inspiring hyperoxic air (HYPER, FiO2: 0.36), but in one trial normoxic air was inspired (HYPER-DEC). In the final TT (NORM-INFORM) the deception was revealed, and cyclists were asked to reproduce their best TT performance while inspiring normoxic air. RESULTS: Greater power output and faster performances occurred when cyclists inspired hyperoxic air in both truthful (HYPER) and deceptive (NORM-DEC) trials compared to NORM (P < 0.001). However, performance only improved in NORM-INFORM (377 W [95% CI 325, 429]) vs NORM (352 W [299, 404]), P < 0.001) when participants (n = 4) completed the trials in the following order: NORM-DEC, NORM, HYPER-DEC, HYPER. CONCLUSIONS: Cycling performance improved with acute exposure to hyperoxia. Mechanisms for the improvement were likely physiological, however improvement in a deception trial suggests an additional placebo effect may be present. Finally, a particular sequence of oxygen deception trials may have built psycho-physiological belief in cyclists such that performance improved in a subsequent normoxic trial.

word count: 249 Main document word and reference count: 3494 words, 30 references Number of figures and tables: 6 figures, 0 tables D ow nl oa de d by A U ST R A L IA N C A T H O L IC U N IV E R SI T Y o n 04 /2 9/ 19 “The Potential to Change Pacing and Performance During 4000-m Cycling Time Trials Using Hyperoxia and Inspired GasContent Deception” by Davies MJ et al. International Journal of Sports Physiology and Performance © 2019 Human Kinetics, Inc.

PURPOSE:There is debate as to which environmental intervention produces the most benefit for team sport athletes, particularly comparing heat and altitude. This quasi-experimental study aimed to compare blood volume (BV) responses with heat and altitude training camps in Australian footballers.METHODS:The BV of 7 professional Australian footballers (91.8 [10.5] kg, 191.8 [10.1] cm) was measured throughout 3 consecutive spring/summer preseasons. During each preseason, players participated in altitude (year 1 and year 2) and heat (year 3) environmental training camps. Year 1 and year 2 altitude camps were in November/December in the United States, whereas the year 3 heat camp was in February/March in Australia after a full exposure to summer heat. BV, red cell volume, and plasma volume (PV) were measured at least 3 times during each preseason.RESULTS:Red cell volume increased substantially following altitude in both year 1 (d = 0.67) and year 2 (d = 1.03), before returning to baseline 4 weeks postaltitude. Immediately following altitude, concurrent decreases in PV were observed during year 1 (d = -0.40) and year 2 (d = -0.98). With spring/summer training in year 3, BV and PV were substantially higher in January than temporally matched postaltitude measurements during year 1 (BV: d = -0.93, PV: d = -1.07) and year 2 (BV: d = -1.99, PV: d = -2.25), with year 3 total BV, red cell volume, and PV not changing further despite the 6-day heat intervention.CONCLUSIONS:We found greater BV after training throughout spring/summer conditions, compared with interrupting spring/summer exposure to train at altitude in the cold, with no additional benefits observed from a heat camp following spring/summer training.

Purpose: To compare the effects of natural altitude training (NAT) and simulated (SIM) live high: train low altitude training on road-race walking performance (min), as well as treadmill threshold walking speed (km.h(-1)) at 4 mmol.L-1 and maximal oxygen consumption, at 1380 m. Methods: Twenty-two elite-level male (n = 15) and female (n = 7) race walkers completed 14 d of NAT at 1380 m (n = 7), SIM live high: train low at 3000: 600 m (n = 7), or control conditions (600-m altitude; CON, n = 8). All preintervention and postintervention testing procedures were conducted at 1380 m and consisted of an incremental treadmill test, completed prior to a 5 x 2-km road-race walking performance test. Differences between groups were analyzed via mixed-model analysis of variance and magnitude-based inferences, with a substantial change detected with > 75% likelihood of exceeding the smallest worthwhile change. Results: The improvement in total performance time for the 5 x 2-km test in NAT was not substantially different from SIM but was substantially greater (85% likely) than CON. The improvement in percentage decrement in the 5 x 2-km performance test in NAT was greater than in both SIM (93% likely) and CON (93% likely). The increase in maximal oxygen consumption was substantially greater (91% likely) in NAT than in SIM. Improvement in threshold walking speed was substantially greater than CON for both SIM (91% likely) and NAT (90% likely). Conclusions: Both NAT and SIM may allow athletes to achieve reasonable acclimation prior to competition at low altitude.

ABSTRACT Introduction We sought to determine the effect of low and moderate normobaric hypoxia on oxygen consumption and anaerobic contribution during interval running at different exercise intensities. Methods Eight runners (age, 25 ± 7 yr, V˙O 2max : 72.1 ± 5.6 mL·kg −1 ·min −1 ) completed three separate interval sessions at threshold (4 × 5 min, 2-min recovery), V˙O 2max (8 × 90 s, 90-s recovery), and race pace (10 × 45 s, 1 min 45 s recovery) in each of; normoxia (elevation: 580 m, FiO 2 : 0.21), low (1400 m, 0.195) or moderate (2100 m, 0.18) normobaric hypoxia. The absolute running speed for each intensity was kept the same at each altitude to evaluate the effect of FiO 2 on physiological responses. Expired gas was collected throughout each session, with total V˙O 2 and accumulated oxygen deficit calculated. Data were compared using repeated-measures ANOVA. Results There were significant differences between training sessions for peak and total V˙O 2 , and anaerobic contribution ( P < 0.001, P = 0.01 respectively), with race pace sessions eliciting the lowest and highest responses respectively. Compared to 580 m, total V˙O 2 at 2100 m was significantly lower ( P < 0.05), and anaerobic contribution significantly higher ( P < 0.05) during both threshold and V˙O 2max sessions. No significant differences were observed between altitudes for race pace sessions. Conclusions To maintain oxygen flux, completing acute exercise at threshold and V˙O 2max intensity at 1400 m simulated altitude appears more beneficial compared with 2100 m. However, remaining at moderate altitude is a suitable when increasing the anaerobic contribution to exercise is a targeted response to training.

The purpose of this study was to determine the influence of 14 days of normobaric hypoxic simulated altitude exposure at 3000 m on the human plasma metabolomic profile. For 14 days, 10 well-trained endurance runners (six men and four women; 29 +/- 7 years of age) lived at 3000 m simulated altitude, accumulating 196.4 +/- 25.6 h of hypoxic exposure, and trained at similar to 600 m. Resting plasma samples were collected at baseline and on days 3 and 14 of altitude exposure and stored at -80 degrees C. Plasma samples were analysed using liquid chromatography-high-resolution mass spectrometry to construct a metabolite profile of altitude exposure. Mass spectrometry of plasma identified 36 metabolites, of which eight were statistically significant (false discovery rate probability 0.1) from baseline to either day 3 or day 14. Specifically, changes in plasma metabolites relating to amino acid metabolism (tyrosine and proline), glycolysis (adenosine) and purine metabolism (adenosine) were observed during altitude exposure. Principal component canonical variate analysis showed significant discrimination between group means (P < 0.05), with canonical variate 1 describing a non-linear recovery trajectory from baseline to day 3 and then back to baseline by day 14. Conversely, canonical variate 2 described a weaker non-recovery trajectory and increase from baseline to day 3, with a further increase from day 3 to 14. The present study demonstrates that metabolomics can be a useful tool to monitor metabolic changes associated with altitude exposure. Furthermore, it is apparent that altitude exposure alters multiple metabolic pathways, and the time course of these changes is different over 14 days of altitude exposure.

The questionable efficacy of Live High Train High altitude training (LHTH) is compounded by minimal training quantification in many studies. We sought to quantify the training load (TL) periodization in a cohort of elite runners completing LHTH immediately prior to competition. Eight elite runners (6 males, 2 females) with a V̇O2peak of 70 ± 4 mL·kg-1·min-1 were monitored during 4 weeks of sea-level training, then 3-4 weeks LHTH in preparation for sea-level races following descent to sea-level. TL was calculated using the session rating of perceived exertion (sRPE) method, whereby duration of each training session was multiplied by its sRPE, then summated to give weekly TL. Performance was assessed in competition at sea-level before, and within 8 days of completing LHTH, with runners competing in 800 m (n = 1, 1500 m/mile (n = 6) and half-marathon (n = 1). Haemoglobin mass (Hbmass) via CO rebreathing and running economy (RE) were assessed pre and post LHTH. Weekly TL during the first 2 weeks at altitude increased by 75% from preceding sea-level training (p = 0.0004, d = 1.65). During the final week at altitude, TL was reduced by 43% compared to the previous weeks (p = 0.002; d = 1.85). The ratio of weekly TL to weekly training volume increased by 17% at altitude (p = 0.009; d = 0.91) compared to prior sea-level training. Hbmass increased by 5% from pre- to post-LHTH (p = 0.006, d = 0.20). Seven athletes achieved lifetime personal best performances within 8 days post-altitude (overall improvement 1.1 ± 0.7%, p = 0.2, d = 0.05). Specific periodization of training, including large increases in training load upon arrival to altitude (due to increased training volume and greater stress of training in hypoxia) and tapering, were observed during LHTH in elite runners prior to personal best performances. Periodization should be individualized and align with timing of competition post-altitude.

Purpose Iron is integral for erythropoietic adaptation to hypoxia, yet the importance of supplementary iron compared with existing stores is poorly understood. The aim of the present study was to compare the magnitude of the hemoglobin mass (Hbmass) in response to altitude in athletes with intravenous (IV), oral, or placebo iron supplementation. Methods Thirty-four, nonanemic, endurance-trained athletes completed 3 wk of simulated altitude (3000 m, 14 h·d−1), receiving two to three bolus iron injections (ferric carboxymaltose), daily oral iron supplementation (ferrous sulfate), or a placebo, commencing 2 wk before and throughout altitude exposure. Hbmass and markers of iron regulation were assessed at baseline (day −14), immediately before (day 0), weekly during (days 8 and 15), and immediately, 1, 3, and 6 wk after (days 22, 28, 42, and 63) the completion of altitude exposure. Results Hbmass significantly increased after altitude exposure in athletes with IV (mean % [90% confidence interval (CI)], 3.7% [2.8–4.7]) and oral (3.2% [2.2–4.2]) supplementation and remained elevated at 7 d postaltitude in oral (2.9% [1.5–4.3]) and 21 d after in IV (3.0% [1.5–4.6]) supplementation. Hbmass was not significantly higher than baseline at any time point in placebo. Conclusions Iron supplementation appears necessary for optimal erythropoietic adaptation to altitude exposure. IV iron supplementation during 3 wk of simulated live high–train low altitude training offered no additional benefit in terms of the magnitude of the erythropoietic response for nonanemic endurance athletes compared with oral supplementation.

PURPOSE:To examine the effect of postexercise cold-water immersion (CWI) protocols, compared with control (CON), on the magnitude and time course of core temperature (Tc) responses. METHODS:Pooled-data analyses were used to examine the Tc responses of 157 subjects from previous postexercise CWI trials in the authors' laboratories. CWI protocols varied with different combinations of temperature, duration, immersion depth, and mode (continuous vs intermittent). Tc was examined as a double difference (ΔΔTc), calculated as the change in Tc in CWI condition minus the corresponding change in CON. The effect of CWI on ΔΔTc was assessed using separate linear mixed models across 2 time components (component 1, immersion; component 2, postintervention). RESULTS:Intermittent CWI resulted in a mean decrease in ΔΔTc that was 0.25°C (0.10°C) (estimate [SE]) greater than continuous CWI during the immersion component (P = .02). There was a significant effect of CWI temperature during the immersion component (P = .05), where reductions in water temperature of 1°C resulted in decreases in ΔΔTc of 0.03°C (0.01°C). Similarly, the effect of CWI duration was significant during the immersion component (P = .01), where every 1 min of immersion resulted in a decrease in ΔΔTc of 0.02°C (0.01°C). The peak difference in Tc between the CWI and CON interventions during the postimmersion component occurred at 60 min postintervention. CONCLUSIONS:Variations in CWI mode, duration, and temperature may have a significant effect on the extent of change in Tc. Careful consideration should be given to determine the optimal amount of core cooling before deciding which combination of protocol factors to prescribe.

PURPOSE:To determine the effect of altitude training at 1600 and 1800 m on sea-level (SL) performance in national-level runners.METHODS:After 3 wk of SL training, 24 runners completed a 3-wk sojourn at 1600 m (ALT1600, n = 8), 1800 m (ALT1800, n = 9), or SL (CON, n = 7), followed by up to 11 wk of SL racing. Race performance was measured at SL during the lead-in period and repeatedly postintervention. Training volume (in kilometers) and load (session rating of perceived exertion) were calculated for all sessions. Hemoglobin mass was measured via CO rebreathing. Between-groups differences were evaluated using effect sizes (Hedges g).RESULTS:Performance improved in both ALT1600 (mean [SD] 1.5% [0.9%]) and ALT1800 (1.6% [1.3%]) compared with CON (0.4% [1.7%]); g = 0.83 (90% confidence limits -0.10, 1.66) and 0.81 (-0.09, 1.62), respectively. Season-best performances occurred 5 to 71 d postaltitude in ALT1600/1800. There were large increases in training load from lead-in to intervention in ALT1600 (48% [32%]) and ALT1800 (60% [31%]) compared with CON (18% [20%]); g = 1.24 (0.24, 2.08) and 1.69 (0.65, 2.55), respectively. Hemoglobin mass increased in ALT1600 and ALT1800 (∼4%) but not CON.CONCLUSIONS:Larger improvements in performance after altitude training may be due to the greater overall load of training in hypoxia compared with normoxia, combined with a hypoxia-mediated increase in hemoglobin mass. A wide time frame for peak performances suggests that the optimal window to race postaltitude is individual, and factors other than altitude exposure per se may be important.

Altitude is a confounding factor within the Athlete Biological Passport (ABP) due, in part, to the plasma volume (PV) response to hypoxia. Here, a newly developed PV blood test is applied to assess the possible efficacy of reducing the influence of PV on the volumetric ABP markers; haemoglobin concentration ([Hb]) and the OFF-score. Endurance athletes (n=34) completed a 21-night simulated live-high train-low (LHTL) protocol (14 h.d-1 at 3000 m). Bloods were collected twice pre-altitude; at days 3, 8, and 15 at altitude; and 1, 7, 21, and 42 days post-altitude. A full blood count was performed on the whole blood sample. Serum was analysed for transferrin, albumin, calcium, creatinine, total protein, and low-density lipoprotein. The PV blood test (consisting of the serum markers, [Hb] and platelets) was applied to the ABP adaptive model and new reference predictions were calculated for [Hb] and the OFF-score, thereby reducing the PV variance component. The PV correction refined the ABP reference predictions. The number of atypical passport findings (ATPFs) for [Hb] was reduced from 7 of 5 subjects to 6 of 3 subjects. The OFF-score ATPFs increased with the PV correction (from 9 to 13, 99% specificity); most likely the result of more specific reference limit predictions combined with the altitude-induced increase in red cell production. Importantly, all abnormal biomarker values were identified by a low confidence value. Although the multifaceted, individual physiological response to altitude confounded some results, the PV model appears capable of reducing the impact of PV fluctuations on [Hb].

[PDF] [Full Text] [Abstract] , November 1, 2006; 101 (5): 1386-1393. J Appl Physiol Stray-Gundersen and Benjamin D. Levine Christopher J. Gore, Ferran A. Rodríguez, Martin J. Truijens, Nathan E. Townsend, James hypobaric hypoxia (4,000–5,500 m) Increased serum erythropoietin but not red cell production after 4 wk of intermittent [PDF] , July 23, 2007; . Integr. Comp. Biol. Reid, Heikki K. Rusko, Heikki O. Tikkanen, and Katherine A. Wilkinson Maurer, Michelle McGuire, Brooke M. Miller, Ken D. O’Halloran, Rüdiger J. Paul, Stephen G. Soliz, Bettina Zeis, Elizabeth K. Fergusson, Zhenxing Fu, Max Gassmann, Cindy B. Kim, Jana Ryan W. Bavis, Frank L. Powell, Aidan Bradford, Connie C.W. Hsia, Juha E. Peltonen, Jorge Respiratory plasticity in response to changes in oxygen supply and demand [PDF] [Full Text] [Abstract] , October , 2007; 47 (4): 532-551. Integr. Comp. Biol. Reid, Heikki K. Rusko, Heikki O. Tikkanen and Katherine A. Wilkinson Maurer, Michelle McGuire, Brooke M. Miller, Ken D. O'Halloran, Rüdiger J. Paul, Stephen G. Soliz, Bettina Zeis, Elizabeth K. Fergusson, Zhenxing Fu, Max Gassmann, Cindy B. Kim, Jana Ryan W. Bavis, Frank L. Powell, Aidan Bradford, Connie C.W. Hsia, Juha E. Peltonen, Jorge Respiratory plasticity in response to changes in oxygen supply and demand [PDF] [Full Text] [Abstract] , November 1, 2007; 103 (5): 1523-1535. J Appl Physiol Christopher J. Gore and Benjamin D. Levine Ferran A. Rodríguez, Martin J. Truijens, Nathan E. Townsend, James Stray-Gundersen, exposure plus sea level training Performance of runners and swimmers after four weeks of intermittent hypobaric hypoxic [PDF] [Full Text] [Abstract] , February 1, 2008; 104 (2): 328-337. J Appl Physiol Christopher J. Gore and Benjamin D. Levine Martin J. Truijens, Ferran A. Rodríguez, Nathan E. Townsend, James Stray-Gundersen, submaximal economy in well-trained swimmers and runners The effect of intermittent hypobaric hypoxic exposure and sea level training on

Altitude training is associated with changes in blood markers, which can confound results of the Athlete?s Biological Passport (ABP). This meta-analysis aims to describe the fluctuations during- and post-altitude in key ABP variables; hemoglobin concentration ([Hb]), square-root transformed reticulocyte percentage (sqrt(retic%)) and the OFF-score. Individual de-identified raw data were provided from 17 studies. Separate linear mixed effects analyses were performed for delta values from baseline for [Hb], sqrt(retic%) and OFF-score, by altitude phase (during and post). Mixed models were fitted with the hierarchical structure: study and subject within study as random effects. Delta values as response variables and altitude dose (in kilometer hours; km.hr = altitude (m) / 1000 x hours), sex, age, protocol and baseline values as fixed effects. Allowances were made for potential autocorrelation. Within two days at natural altitude [Hb] rapidly increased. Subsequent delta [Hb] values increased with altitude dose, reaching a plateau of 0.94 g/dL [95%CI (0.69, 1.20)] at ~1000 km.hr. Delta sqrt(retic%) and OFF-score were the first to identify an erythrocyte response, with respective increases and decreases observed within 100 to 200 km.hr. Post-altitude, [Hb] remained elevated for two weeks. Delta sqrt(retic%) declined below baseline, the magnitude of change was dependent on altitude dose. Baseline values were a significant covariate (p<0.05). The response to altitude is complex resulting in a wide range of individual responses, influenced primarily by altitude dose and baseline values. Improved knowledge of the plausible hematological variations during- and post-altitude provides fundamental information for both the ABP expert and sports physician.

There is evidence to suggest athletes have adopted recombinant human erythropoietin (rHuEPO) dosing regimens that diminish the likelihood of being caught by direct detection techniques. However, the temporal response in physiology, performance, and Athlete Biological Passport (ABP) parameters to such regimens is not clearly understood. Participants were assigned to a high-dose only group (HIGH, n = 8, six rHuEPO doses of 250 IU/kg over two weeks), a combined high micro-dose group (COMB, n = 8, high-dose plus nine rHuEPO micro-doses over a further three weeks), or one of two placebo control groups who received saline in the same pattern as the HIGH (HIGH-PLACEBO, n = 4) or COMB (COMB-PLACEBO, n = 4) groups. Temporal changes in physiology and performance were tracked by graded exercise test (GXT) and haemoglobin mass assessment at baseline, after high dose, after micro-dose (COMB and COMB-PLACEBO only) and after a four-week washout. Venous blood samples were collected throughout the baseline, rHuEPO administration, and washout periods to determine the haematological and ABP response to each dosing regimen. Physiological adaptations induced by a two-week rHuEPO high-dose were maintained by rHuEPO micro-dosing for at least three weeks. However, all participants administered rHuEPO registered at least one suspicious ABP value during the administration or washout periods. These results indicate there is sufficient sensitivity in the ABP to detect use of high rHuEPO doping regimens in athletic populations and they provide important empirical examples for use by anti-doping experts. Copyright © 2017 John Wiley & Sons, Ltd.

Objectives: Actical (R) actigraphy is commonly used to monitor athlete sleep. The proprietary software, called Actiware (R), processes data with three different sleep-wake thresholds (Low, Medium or High), but there is no standardisation regarding their use. The purpose of this study was to examine validity and bias of the sleep-wake thresholds for processing Actical (R) sleep data in team sport athletes.Design: Validation study comparing actigraph against accepted gold standard polysomnography (PSG).Methods: Sixty seven nights of sleep were recorded simultaneously with polysomnography and Actical (R) devices. Individual night data was compared across five sleep measures for each sleep-wake threshold using Actiware (R) software. Accuracy of each sleep-wake threshold compared with PSG was evaluated from mean bias with 95% confidence limits, Pearson moment-product correlation and associated standard error of estimate.Results: The Medium threshold generated the smallest mean bias compared with polysomnography for total sleep time (8.5 min), sleep efficiency (1.8%) and wake after sleep onset (-4.1 min); whereas the Low threshold had the smallest bias (7.5 min) for wake bouts. Bias in sleep onset latency was the same across thresholds (-9.5 min). The standard error of the estimate was similar across all thresholds; total sleep time similar to 25 min, sleep efficiency similar to 4.5%, wake after sleep onset 21 min, and wake bouts 8 counts.Conclusions: Sleep parameters measured by the Actical (R) device are greatly influenced by the sleep-wake threshold applied. In the present study the Medium threshold produced the smallest bias for most parameters compared with PSG. Given the magnitude of measurement variability, confidence limits should be employed when interpreting changes in sleep parameters. (C) 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

[PDF] [Full Text] [Abstract] , April 1, 2001; 90 (4): 1431-1440. J Appl Physiol Mori and Miharu Miyamura Keisho Katayama, Yasutake Sato, Yoshifumi Morotome, Norihiro Shima, Koji Ishida, Shigeo chemosensitivity during hypoxic exercise and hypoxic 2 O Intermittent hypoxia increases ventilation and Sa [PDF] [Full Text] [Abstract] , October 1, 2002; 93 (4): 1498-1505. J Appl Physiol Sally A. Clark, Tahnee Kinsman, John A. Hawley and Chin-Moi Chow Nathan E. Townsend, Christopher J. Gore, Allan G. Hahn, Michael J. McKenna, Robert J. Aughey, athletes Living high-training low increases hypoxic ventilatory response of well-trained endurance

The integrity of the athlete biological passport (ABP) is underpinned by understanding normal fluctuations of its biomarkers to environmental or medical conditions, for example, altitude training or iron deficiency. The combined impact of altitude and iron supplementation on the ABP was evaluated in endurance-trained athletes (n = 34) undertaking 3 weeks of simulated live-high: train-low (14 h.d-1 , 3000 m). Athletes received either oral, intravenous (IV) or placebo iron supplementation, commencing 2 weeks prior and continuing throughout hypoxic exposure. Venous blood was sampled twice prior, weekly during, and up to 6 weeks after altitude. Individual ABP thresholds for haemoglobin concentration ([Hb]), reticulocyte percentage (%retic), and OFF score were calculated using the adaptive model and assessed at 99% and 99.9% specificity. Eleven athletes returned values outside of the calculated reference ranges at 99%, with 8 at 99.9%. The percentage of athletes exceeding the thresholds in each group was similar, but IV returned the most individual occurrences. A similar frequency of abnormalities occurred across the 3 biomarkers, with abnormal [Hb] and OFF score values arising mainly during-, and %retic values mainly post- altitude. Removing samples collected during altitude from the model resulted in 10 athletes returning abnormal values at 99% specificity, 2 of whom had not triggered the model previously. In summary, the abnormalities observed in response to iron supplementation and hypoxia were not systematic and mostly in line with expected physiological adaptations. They do not represent a uniform weakness in the ABP. Nevertheless, altitude training and iron supplementation should be carefully considered by experts evaluating abnormal ABP profiles.

Previous studies have reported improved sea level performance and increased haemoglobin mass (Hbmass) following hypoxic doses of varying magnitude. Less research has focused on the periodisation of training during hypoxic exposure which may influence subsequent performance. PURPOSE: To determine the effect of intensified training and tapering during different doses of Live High Train High (LHTH) altitude on sea level performance and Hbmass in elite runners. METHODS: Twenty one runners completed one of three LHTH altitude camps following 4 weeks of sea level training; 22 days at 1720 m (MOD22; n = 7; VO2 max = 71 ± 4 mL.min.kg-1), 22 days at 2100 m (HI22; n = 4; 67 ± 3 mL.min.kg-1) or 30 days at 2100 m (HI30; n = 10; 70 ± 4 mL.min.kg-1). Hbmass was assessed via CO rebreathing immediately pre and post LHTH, and sea level performance was measured in competitive races completed pre and within 2 weeks post. For each training session, Training Load (TL) was calculated using the session RPE method. Training Stress Balance (TSB) was calculated as the ratio between 7 and 28 day exponentially weighted moving averages. Differences between groups were assessed using one-way ANOVA, with the Kruskal-Wallis test used when assumptions were violated (TSB). RESULTS: Race performance improved by 0.6 ± 1.5 % overall, with similar improvements in HI22 (0.9 ± 0.5 %) and HI30 (0.9 ± 0.9 %); however these were not significantly different to MOD22 (0.1 ± 2.3 %). Performance improvements were achieved by all 4 participants in HI22, 9 of 10 in HI30 and 4 of 7 in MOD22 (4, 7 and 3 lifetime bests respectively). Hbmass was increased from baseline in all groups (MOD22 = 4.4 ± 4.6 %; HI22 = 6.0 ± 2.1 %; HI30 = 4.0 ± 3.1 %). Weekly TL during the first 2 weeks of LHTH was similarly increased in all groups compared to preceding sea level training (range 58 ± 13 % to 72 ± 27 %). TSB at the start of LHTH in MOD22 (132 ± 21) was significantly higher (p < 0.03) than HI22 (94 ± 11) but not HI30 (95 ± 11; p = 0.10). TL for the final week of LHTH was reduced significantly less (p ≤ 0.03) from weeks 1 and 2 in MOD22 (23 ± 13 %) than in HI22 (44 ± 5 %) or HI30 (41 ± 10 %). CONCLUSIONS: Lifetime best sea level performances were achieved following various doses of LHTH. Substantial increases in training load were observed within the first 2 weeks at altitude, and tapering concluding LHTH appeared beneficial for optimal performance.

PerspectivesLast Word on Viewpoint: Time for a new metric for hypoxic dose?Laura A. Garvican-Lewis, Ken Sharpe, and Christopher J. GoreLaura A. Garvican-LewisUniversity of Canberra Research Institute for Sport and Exercise, Canberra, Australia; Physiology, Australian Institute of Sport, Canberra, Australia; and , Ken SharpeSchool of Mathematics and Statistics, The University of Melbourne, Australia, and Christopher J. GoreUniversity of Canberra Research Institute for Sport and Exercise, Canberra, Australia; Physiology, Australian Institute of Sport, Canberra, Australia; and Published Online:22 Jul 2016MoreSectionsPDF (26 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat to the editor: The commentaries (see Ref. 3) provided on our Viewpoint (2) is valuable and insightful. Our model is not without its limitations, as many have highlighted, particularly because we were unable to account for substantial variation in the response of hemoglobin mass (Hbmass) to altitude training both between and within subjects. To that end, our model should be viewed as a small step forward in an area where more work is required.A number of the commentaries highlighted the need for a minimum threshold dose. We concur completely, and pointed out as much in the final paragraph of our Viewpoint. Both a minimum extent of hypoxia and minimum exposure time are required. Indeed, the hypoxic dose is a key factor when adopting altitude training to elicit gains in Hbmass. Time in hypoxia is a key point of difference between both live high, train high and live high, train low methods compared with intermittent hypoxic training or intermittent hypoxic exposure methods, because the latter two involve an insufficient hypoxic dose to increase Hbmass based on duration rather than severity of hypoxia.Further exploration of our data set using a regression splines model did not provide substantive evidence of a threshold effect for altitude dose. The model suggests that a kilometer-hour exposure in excess of 250 should, on average, be sufficient to produce an increase in Hbmass. However, given the amount of variation observed between individuals, due to both the natural variation between individuals and the analytical error associated with measuring Hbmass, it is not possible to ascertain how individual athletes may respond to such a low dose of altitude. Furthermore, our data set is limited by the small number of data points at the lower end of the kilometer-hour range; to explore the issue of a possible threshold more effectively would require considerably more data at the lower end of the range.As is evident from the figure we presented in our Viewpoint, there is more than one model that provides a similar fit of the data. Any model is, of necessity, a simplification that is unlikely to be “correct”; to quote the famous statistician George Box (1) “all models are wrong, but some are useful.”DISCLOSURESNo conflicts of interest, financial or otherwise, are declared by the author(s).AUTHOR CONTRIBUTIONSL.A.G.-L., K.S., and C.J.G. drafted manuscript; L.A.G.-L., K.S., and C.J.G. edited and revised manuscript; L.A.G.-L., K.S., and C.J.G. approved final version of manuscript.REFERENCES1. Box GEP, Hunter JS, Hunter WG. Statistics for Experimenters (2nd ed.). NY: John Wiley & Sons, 2005.Google Scholar2. Garvican-Lewis LA, Sharpe K, Gore CJ. Viewpoint: Time for a new metric for hypoxic dose? J Appl Physiol; doi:10.1152/japplphysiol.00579.2015.Link | ISI | Google Scholar3. Millet GP, Brocherie F, Girard O, Wehrlin JP, Troesch S, Hauser A, Steiner T, Peltonen JE, Rusko HK, Constantini K, Fulton TJ, Hursh DG, Noble TJ, Paris HLR, Wiggins CC, Chapman RF, Levine BD, Kumar VHS, Schmidt WFJ. Commentaries on Viewpoint: Time for a new metric for hypoxic dose? J Appl Physiol; doi:10.1152/japplphysiol.00460.2016.Link | Google ScholarAUTHOR NOTESAddress for reprint requests and other correspondence: L. Garvican-Lewis, Research Institute for Sport and Exercise, Univ. of Canberra, Bruce, ACT, Australia (e-mail: laura.[email protected]gov.au). Download PDF Previous Back to Top Next FiguresReferencesRelatedInformation Cited ByHypobaric live high-train low does not improve aerobic performance more than live low-train low in cross-country skiers22 March 2018 | Scandinavian Journal of Medicine & Science in Sports, Vol. 28, No. 6 More from this issue > Volume 121Issue 1July 2016Pages 359-359 Copyright & PermissionsCopyright © 2016 the American Physiological Societyhttps://doi.org/10.1152/japplphysiol.00457.2016PubMed27451277History Published online 22 July 2016 Published in print 1 July 2016 Metrics

The aim of this paper is to provide a Bayesian formulation of the so-called magnitude-based inference approach to quantifying and interpreting effects, and in a case study example provide accurate probabilistic statements that correspond to the intended magnitude-based inferences. The model is described in the context of a published small-scale athlete study which employed a magnitude-based inference approach to compare the effect of two altitude training regimens (live high-train low (LHTL), and intermittent hypoxic exposure (IHE)) on running performance and blood measurements of elite triathletes. The posterior distributions, and corresponding point and interval estimates, for the parameters and associated effects and comparisons of interest, were estimated using Markov chain Monte Carlo simulations. The Bayesian analysis was shown to provide more direct probabilistic comparisons of treatments and able to identify small effects of interest. The approach avoided asymptotic assumptions and overcame issues such as multiple testing. Bayesian analysis of unscaled effects showed a probability of 0.96 that LHTL yields a substantially greater increase in hemoglobin mass than IHE, a 0.93 probability of a substantially greater improvement in running economy and a greater than 0.96 probability that both IHE and LHTL yield a substantially greater improvement in maximum blood lactate concentration compared to a Placebo. The conclusions are consistent with those obtained using a 'magnitude-based inference' approach that has been promoted in the field. The paper demonstrates that a fully Bayesian analysis is a simple and effective way of analysing small effects, providing a rich set of results that are straightforward to interpret in terms of probabilistic statements.