Construction of a Machine Learning Model to Estimate Physiological Variables of Speed Skating Athletes Under Hypoxic Training Conditions

ABSTRACT

Han, J, Liu, M, Shi, J, and Li, Y. Construction of a machine learning model to estimate physiological variables of speed skating athletes under hypoxic training conditions. J Strength Cond Res 37(7): 1543-1550, 2023-Monitoring changes in athletes' physiological variables is essential to create a safe and effective hypoxic training plan for speed skating athletes. This research aims to develop a machine learning estimation model to estimate physiological variables of athletes under hypoxic training conditions based on their physiological measurements collected at sea level. The research team recruited 64 professional speed skating athletes to participate in a 10-week training program, including 3 weeks of sea-level training, followed by 4 weeks of hypoxic training and then a 3-week sea-level recovery period. We measured several physiological variables that could reflect the athletes' oxygen transport capacity in the first 7 weeks, including red blood cell (RBC) count and hemoglobin (Hb) concentration. The physiological variables were measured once a week and then modeled as a mathematical model to estimate measurements' changes using the maximum likelihood method. The mathematical model was then used to construct a machine learning model. Furthermore, the original data (measured once per week) were used to construct a polynomial model using curve fitting. We calculated and compared the mean absolute error between estimated values of the 2 models and measured values. Our results show that the machine learning model estimated RBC count and Hb concentration accurately. The errors of the estimated values were within 5% of the measured values. Compared with the curve fitting polynomial model, the accuracy of the machine learning model in estimating hypoxic training's physiological variables is higher. This study successfully constructed a machine learning model that used physiological variables measured at the sea level to estimate the physiological variables during hypoxic training.

Training Characteristics and Competitive Demands in Women Road Cyclists: A Systematic Review

PURPOSE

To identify the main training characteristics and competitive demands in women's road cycling.

METHODS

A systematic search was conducted on 5 databases according to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. The articles had to be primary studies, written after 1990 with a sample of competitive women between the ages of 15 and 50. The Quality Assessment Tool for Quantitative Studies and the Oxford Levels of Evidence scales were used.

RESULTS

The search yielded 1713 articles, of which 20 were included. Studies on training and competitive demands (n = 5) found that both external and internal loads are higher in women than in men. Studies on strength and endurance training (n = 5) showed that both velocity-based and heavy-load strength training programs performed at least 2 days per week and including 3 to 4 lower-body exercises improved performance. Altitude-training studies (n = 3) found that "Live High-Train Low" was effective to increase performance during the first 9 days after the training camp. The 7 remaining studies focused on a range of topics. The methodological quality was strong for 12 studies and moderate for 8. In contrast, the level of evidence was high in 7 and low in the other 13.

CONCLUSIONS

Endurance training and competitive demands in women's road cycling are higher than those of men. Strength training is effective in women when the frequency, intensity, and number of exercises are appropriate, while altitude training should be completed a few days before competing. Further studies are warranted to better define the participants' competitive level, using a methodological design with a higher level of evidence.

Altitude and Erythropoietin: Comparative Evaluation of Their Impact on Key Parameters of the Athlete Biological Passport: A Review

The hematological module of the Athlete's Biological Passport (ABP) identifies doping methods and/or substances used to increase the blood's capacity to transport or deliver oxygen to the tissues. Recombinant human erythropoietin (rhEPOs) are doping substances known to boost the production of red blood cells and might have an effect on the blood biomarkers of the ABP. However, hypoxic exposure influences these biomarkers similarly to rhEPOs. This analogous impact complicates the ABP profiles' interpretation by antidoping experts. The present study aimed to collect and identify, through a literature search, the physiological effects on ABP blood biomarkers induced by these external factors. A total of 43 studies were selected for this review. A positive correlation (R² = 0.605, r = 0.778, p < 0.001) was identified between the hypoxic dose and the increase in hemoglobin concentration (HGB) percentage. In addition, the change in the reticulocyte percentage (RET%) has been identified as one of the most sensitive parameters to rhEPO use. The mean effects of rhEPO on blood parameters were greater than those induced by hypoxic exposure (1.7 times higher for HGB and RET% and 4 times higher for hemoglobin mass). However, rhEPO micro-doses have shown effects that are hardly distinguishable from those identified after hypoxic exposure. The results of the literature search allowed to identify temporal and quantitative evolution of blood parameters in connection with different hypoxic exposure doses, as well as different rhEPOs doses. This might be considered to provide justified and well-documented interpretations of physiological changes in blood parameters of the Athlete Biological Passport.

Four weeks of high-intensity training in moderate, but not mild hypoxia improves performance and running economy more than normoxic training in horses

We investigated whether horses trained in moderate and mild hypoxia demonstrate greater improvement in performance and aerobic capacity compared to horses trained in normoxia and whether the acquired training effects are maintained after 2 weeks of post‐hypoxic training in normoxia. Seven untrained Thoroughbred horses completed 4 weeks (3 sessions/week) of three training protocols, consisting of 2‐min cantering at 95% maximal oxygen consumption V˙O2max under two hypoxic conditions (H16, F_IO₂ = 16%; H18, F_IO₂ = 18%) and in normoxia (N21, F_IO₂ = 21%), followed by 2 weeks of post‐hypoxic training in normoxia, using a randomized crossover study design with a 3‐month washout period. Incremental treadmill tests (IET) were conducted at week 0, 4, and 6. The effects of time and groups were analyzed using mixed models. Run time at IET increased in H16 and H18 compared to N21, while speed at V˙O2max was increased significantly only in H16. V˙O2max in all groups and cardiac output at exhaustion in H16 and H18 increased after 4 weeks of training, but were not significantly different between the three groups. In all groups, run time, V˙O2max, VV˙O2max, Q˙max, and lactate threshold did not decrease after 2 weeks of post‐hypoxic training in normoxia. These results suggest that 4 weeks of training in moderate (H16), but not mild (H18) hypoxia elicits greater improvements in performance and running economy than normoxic training and that these effects are maintained for 2 weeks of post‐hypoxic training in normoxia.

Hematological adaptations and detection of recombinant human erythropoietin combined with chronic hypoxia

This study evaluated whether recombinant human erythropoietin (rhEpo) treatment combined with chronic hypoxia provided an additive erythropoietic response and whether the athlete biological passport (ABP) sensitivity improved with hypoxia. Two interventions were completed, each containing 4 weeks baseline, 4 weeks exposure at sea level or 2,320 m of altitude, and 4 weeks follow-up. Participants were randomly assigned to 20 IU·kg bw^-1 rhEpo or placebo injections every second day for 3 weeks during the exposure period at sea level (rhEpo n = 25, placebo n = 9) or at altitude (rhEpo n = 12, placebo n = 27). Venous blood was analyzed weekly. Combining rhEpo and hypoxia induced larger changes compared with rhEpo or hypoxia alone for [Hb] (p < 0.001 and p > 0.05, respectively), reticulocyte percentage (p < 0.001), and OFF-hr score (p < 0.01 and p < 0.001, respectively). The most pronounced effect was observed for reticulocyte percentage with up to ~35% (p < 0.001) and ~45% (p < 0.001) higher levels compared with rhEpo or hypoxia only, respectively. The ABP sensitivity for the combined treatment was 54 and 35 percentage points higher for [Hb] (p < 0.05) and reticulocyte percentage (p < 0.05), respectively, but similar for OFF-hr score, compared with rhEpo at sea level. Across any time point, [Hb] and OFF-hr score combined identified 14 unique true-positive participants (56%) at sea level and 12 unique true-positive participants (100%) at altitude. However, a concurrent reduction in specificity existed at altitude. In conclusion, rhEpo treatment combined with hypoxic exposure provided an additive erythropoietic response compared with rhEpo or hypoxic exposure alone. Correspondingly, ABP was more sensitive to rhEpo at altitude than at sea level, but a compromised specificity existed with hypoxic exposure.

Impact of Energy Availability, Health, and Sex on Hemoglobin-Mass Responses Following Live-High-Train-High Altitude Training in Elite Female and Male Distance Athletes

PURPOSE

The authors investigated the effects of sex, energy availability (EA), and health status on the change in hemoglobin mass (ΔHbmass) in elite endurance athletes over ∼3-4 wk of live-high-train-high altitude training in Flagstaff, AZ (2135 m; n = 27 women; n = 21 men; 27% 2016 Olympians).

METHODS

Precamp and postcamp Hbmass (optimized carbon monoxide rebreathing method) and iron status were measured, EA was estimated via food and training logs, and a Low Energy Availability in Females Questionnaire (LEAFQ) and a general injury/illness questionnaire were completed. Hypoxic exposure (h) was calculated with low (<500 h), moderate (500-600 h), and high (>600 h) groupings.

RESULTS

Absolute and relative percentage ΔHbmass was significantly greater in women (6.2% [4.0%], P < .001) than men (3.2% [3.3%], P = .008). %ΔHbmass showed a dose-response with hypoxic exposure (3.1% [3.8%] vs 4.9% [3.8%] vs 6.8% [3.7%], P = .013). Hbmass_pre was significantly higher in eumenorrheic vs amenorrheic women (12.2 [1.0] vs 11.3 [0.5] g/kg, P = .004). Although statistically underpowered, %ΔHbmass was significantly less in sick (n = 4, -0.5% [0.4%]) vs healthy (n = 44, 5.4% [3.8%], P < .001) athletes. There were no significant correlations between self-reported iron intake, sex hormones, or EA on Hbmass outcomes. However, there was a trend for a negative correlation between LEAFQ score and %ΔHbmass (r = -.353, P = .07).

CONCLUSIONS

The findings confirm the importance of baseline Hbmass and exposure to hypoxia on increases in Hbmass during altitude training, while emphasizing the importance of athlete health and indices of EA on an optimal baseline Hbmass and hematological response to hypoxia.

Hemolysis during and after 21 days of head-down-tilt bed rest

Hemoconcentration is observed in bed rest studies, descent from altitude, and exposure to microgravity. Hemoconcentration triggers erythrocyte losses to subsequently normalize erythrocyte concentration. The mechanisms of erythrocyte loss may involve enhanced hemolysis, but has never been measured directly in bed rest studies. Steady‐state hemolysis was evaluated by measuring two heme degradation products, endogenous carbon monoxide concentration [CO] and urobilinogen in feces, in 10 healthy men, before, during, and after two campaigns of 21 days of 6° head‐down‐tilt (HDT) bed rest. The subjects were hemoconcentrated at 10 and 21 days of bed rest: mean concentrations of hemoglobin (15.0 ± 0.2 g/L and 14.6 ± 0.1 g/L, respectively) and erythrocytes (5.18 ± 0.06E6/μL and 5.02 ± 0.06E6/μL, respectively) were increased compared to baseline (all Ps < 0.05). In contrast, mean hemoglobin mass (743 ± 19 g) and number of erythrocytes (2.56 ± 0.07E13) were decreased at 21 days of bed rest (both Ps < 0.05). Indicators of hemolysis mean [CO] (1660 ± 49 ppb and 1624 ± 48 ppb, respectively) and fecal urobilinogen concentration (180 ± 23 mg/day and 199 ± 22 mg/day, respectively) were unchanged at 10 and 21 days of bed rest compared to baseline (both Ps > 0.05). A significant decrease in [CO] (−505 ppb) was measured at day 28 after bed rest. HDT bed rest caused hemoconcentration in parallel with lower hemoglobin mass. Circulating indicators of hemolysis remained unchanged throughout bed rest supporting that enhanced hemolysis did not contribute significantly to erythrocyte loss during the hemoconcentration of bed rest. At day 28 after bed rest, decreased hemolysis accompanied the recovery of erythrocytes, a novel finding.

The Effects of Altitude Training on Erythropoietic Response and Hematological Variables in Adult Athletes: A Narrative Review

Background: One of the goals of altitude training is to increase blood oxygen-carrying capacity in order to improve sea-level endurance performance in athletes. The elevated erythropoietin (EPO) production in hypoxia is a key factor in the achievement of enhanced hematological variables. The level of the EPO increase and acceleration of erythropoiesis depend on the duration of exposure and degree of hypoxia. Furthermore, many other factors may affect the hematological response to altitude training.

Aim: The purpose of this narrative review was to: (1) analyze the kinetics of EPO and hematological variables during and after altitude training; (2) summarize the current state of knowledge about the possible causes of individual or cohort differences in EPO and hematological response to altitude training; (3) formulate practical guidelines for athletes to improve the efficiency of altitude training.

Methods: A narrative review was performed following an electronic search of the databases PubMed/MEDLINE and SPORTDiscus via EBSCO for all English-language articles published between 1997 and 2017.

Results: Complete unification of results from studies on EPO kinetics was difficult due to different time and frequency of blood sampling by different researchers during and after altitude training, but the data presented in the reviewed literature allowed us to detect certain trends. The results of the reviewed studies were divergent and indicated either increase or no change of hematological variables following altitude training. Factors that may affect the hematological response to altitude training include hypoxic dose, training content, training background of athletes, and/or individual variability of EPO production.

Conclusions: Despite the potential benefits arising from altitude training, its effectiveness in improving hematological variables is still debatable. Further research and better understanding of factors influencing the response to altitude, as well as factors affecting the suitable measurement and interpretation of study results, are needed.

The athlete's hematological response to hypoxia: A meta-analysis on the influence of altitude exposure on key biomarkers of erythropoiesis

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.

Live-high train-low improves repeated time-trial and Yo-Yo IR2 performance in sub-elite team-sport athletes

OBJECTIVES

To determine the efficacy of live-high train-low on team-sport athlete physical capacity and the time-course for adaptation.

DESIGN

Pre-post parallel-groups.

METHODS

Fifteen Australian footballers were matched for Yo-Yo Intermittent recovery test level 2 (Yo-YoIR2) performance and assigned to LHTL (n=7) or control (Con; n=8). LHTL spent 19 nights (3×5 nights, 1×4 nights, each block separated by 2 nights at sea level) at 3000-m simulated altitude (F_IO₂: 0.142). Yo-Yo IR2 was performed pre and post 5, 15, and 19 nights. A 2- and 1-km time-trial (TT) was performed pre and post intervention. Haemoglobin mass (Hb_mass) was measured in LHTL after 5, 10, 15, and 19 nights. A contemporary statistical approach using effect size, confidence limits, and magnitude-based inferences was used to measure changes between groups.

RESULTS

Compared to pre, Hb_mass was possibly higher after 15 (3.8%, effect size (ES) 0.19, 90% confidence limits 0.05-0.33) and very likely higher after 19 nights (6.7%, 0.35, 0.10; 0.52). For Yo-Yo IR2, LHTL group change was not meaningfully different to Con after 5 nights, possibly greater after 15 (10.2%, 0.37, -0.29; 1.04), and likely greater after 19 nights (13.5%, 0.49, -0.16; 1.14). Both groups improved 2-km TT, with LHTL improvement possibly higher than CON (1.9%, 0.22, -0.18; 0.62). Only LHTL improved 1-km TT, with LHTL improvement likely greater than CON (4.6%, 0.56, -0.08; 1.04).

CONCLUSIONS

Fifteen nights of LHTL was possibly effective, while 19 nights was effective at increasing Hb_mass, Yo-Yo IR2 and repeated TT performance more than sea-level training.

Curcumin prophylaxis mitigates the incidence of hypobaric hypoxia-induced altered ion channels expression and impaired tight junction proteins integrity in rat brain

Background

The present study was proposed to elucidate the prophylactic role of curcumin in the prevention of hypoxia-induced cerebral edema (HACE).

Methods

Rats were exposed to simulated hypobaric hypoxia at 7620 m for 24 h at 25 ± 1 °C. Transvascular leakage, expression of transcriptional factors (nuclear factor-kappa B (NF-κB) and hypoxia inducible factor 1 alpha (Hif-1α) and also the genes regulated by these transcriptional factors, sodium potassium-adenosine triphosphatase (Na⁺/K⁺-ATPase) and endothelial sodium channel (ENaC) levels and brain tight junction (TJ) proteins like ZO-1, junctional adhesion molecule C (JAMC), claudin 4 and claudin 5 levels were determined in the brain of rats under hypoxia by Western blotting, electro mobility shift assay, ELISA, immunohistochemistry, and histopathology along with haematological parameters. Simultaneously, to rule out the fact that inflammation causes impaired Na⁺/K⁺-ATPase and ENaC functions and disturbing the TJ integrity leading to cerebral edema, the rats were pre-treated with curcumin (100 mg/kg body weight) 1 h prior to 24-h hypoxia.

Results

Curcumin administration to rats, under hypoxia showed a significant decrease (p < 0.001) in brain water content (3.53 ± 0.58 wet-to-dry-weight (W/D) ratio) and transvascular leakage (136.2 ± 13.24 relative fluorescence units per gram (r.f.u./g)) in the brain of rats compared to control (24-h hypoxia) (7.1 ± 1.0 W/D ratio and 262.42 ± 24.67 r.f.u./g, respectively). Curcumin prophylaxis significantly attenuated the upregulation of NF-κB (p < 0.001), thereby leading to concomitant downregulation of pro-inflammatory cytokine levels (↓IL-1, IL-2, IL-18 and TNF-α), cell adhesion molecules (↓P-selectin and E-selectin) and increased anti-inflammatory cytokine (↑IL-10). Curcumin stabilized the brain HIF-1α levels followed by maintaining VEGF levels along with upregulated Na⁺/K⁺-ATPase and ENaC levels (p < 0.001) under hypoxia. Curcumin restored the brain ZO-1, JAMC, claudin 4 and claudin 5 levels (p < 0.001) under hypoxia. Histopathological observations revealed the absence of edema and inflammation in the brain of rats supplemented with curcumin.

Conclusions

These results indicate that curcumin is a potent drug in amelioration of HACE as it effectively attenuated inflammation as well as fluid influx by maintaining the tight junction proteins integrity with increased ion channels expression in the brain of rats under hypoxia.

Changes in blood gas transport of altitude native soccer players near sea-level and sea-level native soccer players at altitude (ISA3600)

Objectives

The optimal strategy for soccer teams playing at altitude is not known, that is, ‘fly-in, fly-out’ versus short-term acclimatisation. Here, we document changes in blood gas and vascular volumes of sea-level (Australian, n=20) and altitude (Bolivian, n=19) native soccer players at 3600 m.

Methods

Haemoglobin-oxygen saturation (Hb-sO₂), arterial oxygen content (CaO₂), haemoglobin mass (Hbmass), blood volume (BV) and blood gas concentrations were measured before descent (Bolivians only), together with aerobic fitness (via Yo-YoIR1), near sea-level, after ascent and during 13 days at 3600 m.

Results

At baseline, haemoglobin concentration [Hb] and Hbmass were higher in Bolivians (mean±SD; 18.2±1.0 g/dL, 12.8±0.8 g/kg) than Australians (15.0±0.9 g/dL, 11.6±0.7 g/kg; both p≤0.001). Near sea-level, [Hb] of Bolivians decreased to 16.6±0.9 g/dL, but normalised upon return to 3600 m; Hbmass was constant regardless of altitude. In Australians, [Hb] increased after 12 days at 3600 m to 17.3±1.0 g/dL; Hbmass increased by 3.0±2.7% (p≤0.01). BV decreased in both teams at altitude by ∼400 mL. Arterial partial pressure for oxygen (PaO₂), Hb-sO₂ and CaO₂ of both teams decreased within 2 h of arrival at 3600 m (p≤0.001) but increased over the following days, with CaO₂ overcompensated in Australians (+1.7±1.2 mL/100 mL; p≤0.001). Yo-YoIR1 was lower on the 3rd versus 10th day at altitude and was significantly related to CaO₂.

Conclusions

The marked drop in PaO₂ and CaO₂ observed after ascent does not support the ‘fly-in, fly-out’ approach for soccer teams to play immediately after arrival at altitude. Although short-term acclimatisation was sufficient for Australians to stabilise their CaO₂ (mostly due to loss of plasma volume), 12 days appears insufficient to reach chronic levels of adaption.

Year-to-year variability in haemoglobin mass response to two altitude training camps

Aim

To quantify the year-to-year variability of altitude-induced changes in haemoglobin mass (Hb_mass) in elite team-sport athletes.

Methods

12 Australian-Footballers completed a 19-day (ALT1) and 18-day (ALT2) moderate altitude (∼2100 m), training camp separated by 12 months. An additional 20 participants completed only one of the two training camps (ALT1 additional n=9, ALT2 additional n=11). Total Hb_mass was assessed using carbon monoxide rebreathing before (PRE), after (POST₁) and 4 weeks after each camp. The typical error of Hb_mass for the pooled data of all 32 participants was 2.6%. A contemporary statistics analysis was used with the smallest worthwhile change set to 2% for Hb_mass.

Results

POST₁ Hb_mass was very likely increased in ALT1 (3.6±1.6%, n=19; mean±∼90 CL) as well as ALT2 (4.4±1.3%, n=23) with an individual responsiveness of 1.3% and 2.2%, respectively. There was a small correlation between ALT1 and ALT2 (R=0.21, p=0.59) for a change in Hb_mass, but a moderately inverse relationship between the change in Hb_mass and initial relative Hb_mass (g/kg (R=−0.51, p=0.04)).

Conclusions

Two preseason moderate altitude camps 1 year apart yielded a similar (4%) mean increase in Hb_mass of elite footballers, with an individual responsiveness of approximately half the group mean effect, indicating that most players gained benefit. Nevertheless, the same individuals generally did not change their Hb_mass consistently from year to year. Thus, a ‘responder’ or ‘non-responder’ to altitude for Hb_mass does not appear to be a fixed trait.

Yin and yang, or peas in a pod? Individual-sport versus team-sport athletes and altitude training

The question of whether altitude training can enhance subsequent sea-level performance has been well investigated over many decades. However, research on this topic has focused on athletes from individual or endurance sports, with scant number of studies on team-sport athletes. Questions that need to be answered include whether this type of training may enhance team-sport athlete performance, when success in team-sport is often more based on technical and tactical ability rather than physical capacity per se. This review will contrast and compare athletes from two sports representative of endurance (cycling) and team-sports (soccer). Specifically, we draw on the respective competition schedules, physiological capacities, activity profiles and energetics of each sport to compare the similarities between athletes from these sports and discuss the relative merits of altitude training for these athletes. The application of conventional live-high, train-high; live-high, train-low; and intermittent hypoxic training for team-sport athletes in the context of the above will be presented. When the above points are considered, we will conclude that dependent on resources and training objectives, altitude training can be seen as an attractive proposition to enhance the physical performance of team-sport athletes without the need for an obvious increase in training load.

Altitude training and haemoglobin mass from the optimised carbon monoxide rebreathing method determined by a meta-analysis

OBJECTIVE

To characterise the time course of changes in haemoglobin mass (Hbmass) in response to altitude exposure.

METHODS

This meta-analysis uses raw data from 17 studies that used carbon monoxide rebreathing to determine Hbmass prealtitude, during altitude and postaltitude. Seven studies were classic altitude training, eight were live high train low (LHTL) and two mixed classic and LHTL. Separate linear-mixed models were fitted to the data from the 17 studies and the resultant estimates of the effects of altitude used in a random effects meta-analysis to obtain an overall estimate of the effect of altitude, with separate analyses during altitude and postaltitude. In addition, within-subject differences from the prealtitude phase for altitude participant and all the data on control participants were used to estimate the analytical SD. The 'true' between-subject response to altitude was estimated from the within-subject differences on altitude participants, between the prealtitude and during-altitude phases, together with the estimated analytical SD.

RESULTS

During-altitude Hbmass was estimated to increase by ∼1.1%/100 h for LHTL and classic altitude. Postaltitude Hbmass was estimated to be 3.3% higher than prealtitude values for up to 20 days. The within-subject SD was constant at ∼2% for up to 7 days between observations, indicative of analytical error. A 95% prediction interval for the 'true' response of an athlete exposed to 300 h of altitude was estimated to be 1.1-6%.

CONCLUSIONS

Camps as short as 2 weeks of classic and LHTL altitude will quite likely increase Hbmass and most athletes can expect benefit.

Physiological and performance responses to a preseason altitude-training camp in elite team-sport athletes

PURPOSE

Little research has been done on the physiological and performance effects of altitude training on team-sport athletes. Therefore, this study examined changes in 2000-m time-trial running performance (TT), hemoglobin mass (Hbmass), and intramuscular carnosine content of elite Australian Football (AF) players after a preseason altitude camp.

METHODS

Thirty elite AF players completed 19 days of living and training at either moderate altitude (~2130 m; ALT, n = 21) or sea level (CON, n = 9). TT performance and Hbmass were assessed preintervention (PRE) and postintervention (POST1) in both groups and at 4 wk after returning to sea level (POST2) in ALT only.

RESULTS

Improvement in TT performance after altitude was likely 1.5% (± 4.8-90%CL) greater in ALT than in CON, with an individual responsiveness of 0.8%. Improvements in TT were maintained at POST2 in ALT. Hbmass after altitude was very likely increased in ALT compared with CON (2.8% ± 3.5%), with an individual responsiveness of 1.3%. Hbmass returned to baseline at POST2. Intramuscular carnosine did not change in either gastrocnemius or soleus from PRE to POST1.

CONCLUSIONS

A preseason altitude camp improved TT performance and Hbmass in elite AF players to a magnitude similar to that demonstrated by elite endurance athletes undertaking altitude training. The individual responsiveness of both TT and Hbmass was approximately half the group mean effect, indicating that most players gained benefit. The maintenance of running performance for 4 wk, despite Hbmass returning to baseline, suggests that altitude training is a valuable preparation for AF players leading into the competitive season.