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Intermittent Hypobaric Hypoxia exposure increases ventilatory treshold but not running performance in triathletes

The document summarizes a study that examined the effects of 4 weeks of intermittent hypobaric hypoxia exposure (IHE) on aerobic capacity and running performance in triathletes. The study found that IHE significantly increased ventilatory threshold but did not improve maximal oxygen uptake or running performance. The increases in ventilatory threshold were not due to increased erythropoiesis. While IHE may improve aerobic endurance capacity through other adaptations, more research is needed to determine its effects on highly trained endurance athletes.

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Rodríguez, F.A., Iglesias X., Barrero A., Ábalos X., Moreno D., Abellán R., Segura J. Intermittent Hypobaric Hypoxia Exposure increases ventilatory treshold but not running performance in triathletes. 1st WORLD CONFERENCE OF SCIENCE IN TRIATHLON. Alacant, 2011. Sport Sciences Research Group INEFC Barcelona Grup de Recerca en Ciències de l'Esport INEFC Barcelona Grup Consolidat (2009 SGR1054) Institut Nacional d’Educació Física de Catalunya Av. de l’Estadi, 12-22 08038 Barcelona (Spain) +34 93 425 54 45 grce@gencat.cat @Recerca_INEFC
Intermittent Hypobaric Hypoxia Exposure  Increases Ventilatory Threshold But Not  Running Performance In Triathletes Rodríguez FA, Iglesias X, Barrero A, Ábalos X,  Moreno D, Abellán R, Segura J IMAS Institut Municipal d’Investigació Mèdica. IMIM Pharmacology Research Unit
Contemporary Applications of Hypoxia to Athletic Training Altitude Training Intermittent Hypoxia Natural hypobaric hypoxia Artificial hypoxia at altitude (mountains) (Hypobaric / Normobaric) LH-TH LH-TL LL-TH IHE IHT IHIT High-High High-Low Low-High Intermittent Intermittent IH Interval Hypoxia Hypoxic Training Exposure Training LH-THO2 + Suppl. O2 Rodríguez 2005 ECSS Congress
Please see keynote conference by Dr. Randy Wilber "Training in Altitude“ (12 h)
Contemporary Applications of Hypoxia to Athletic Training Altitude Training Intermittent Hypoxia Natural hypobaric hypoxia Artificial hypoxia at altitude (mountains) (Hypobaric / Normobaric) LH-TH LH-TL LL-TH IHE IHT IHIT High-High High-Low Low-High Intermittent Intermittent IH Interval Hypoxia Hypoxic Training Exposure Training LH-THO2 + Suppl. O2 Rodríguez 2005 ECSS Congress
The short-term IHE model • Short-term IHE in climbers and endurance athletes 9-21 d, 1.5-5 h/d, 4000-5500 m1-8 • Erythropoietic response EPO, PCV, retics1-7 but not Hbmass increase8 • Increased VO2max in climbers (+6.2%)1 and swimmers +5.4%6, +3.3%8, but not in runners8 • Improved performance in middle-distance swimmers +0.9% in 200-m time6, world-class track cyclists +2.9% in 4’ trial)7 but not in swimmers and runners8 1 Casas et al. 1998 J Sports Sci 5 Rodríguez et al. 2000 Eur J Appl Physiol 2 Casas et al. 2000 Aviat Space Environ Med 6 Rodríguez et al. 2002 IX WSBMS 3 Rodríguez et al. 1998 J Sports Sci 7 Rodríguez et al. 2002 7th ECSS Congress, Athens 4 Rodríguez et al. 1999 Med Sci Sports Exerc 8 Rodríguez et al. 2007 J Appl Physiol
Intermittent Hypoxia Study 2003 IHE at hypobaric chamber Randomized, double blind, placebo controlled study 23 trained athletes (10 runners, 13 swimmers) 3-km and 100/400-m time trial (performance markers) submax and maximal VO2 (treadmill or flume) 3 h/d, 5 d/wk, 4 wks Gore et al. 2006 J Appl Physiol Rodríguez et al. 2007 J App Physiol Truijens et al. 2008 J Appl Physiol
Aims • To examine the effect on triathletes of 4 weeks of moderate-severe IHE in a hypobaric chamber (SA 4,000-5,500 m) on aerobic capacity running performance • Hypothesis: aerobic capacity and running performance would further improve in the IHE group as compared to sea level control group
Subjects • 14 male triathletes • Age 19-37 y, height 172-185 cm, body mass 66-84 kg • Regular training 7-25 h/wk • Competing at regional/national level • Continued to train at sea level throughout the study
Experimental Design • Randomised controlled trial • Subjects assigned to HYPO or NORM group (n=7 each) • Very similar training schedule at SL (ave. 20 h/wk) • Same supplementation (Fe, folate, vitamins A, C, & E, Mg) HYPO Sea level training IHE at rest: 4 weeks, 5 d/wk, 3 h/d at 4,000-5,500 m NORM SL training only
Chronogram 6000 Simulated altitude (m) 5000 Treadmill test 4000 Field test (UMTT) 3000 Blood tests 2000 1000 0 1 8 15 22 29 36 43 50 Time (days) t1 t2 t3 t1´ t2´ Pre Post 1 Post 2
Running Field Testing • Université de Montréal Track Test (UMTT)* to determine MAS (vVO2max) in a synthetic 400-m track v0 = 7 km·h-1 v = 1 km·h-1 / 2 min * Léger & Boucher 1980 Can J Appl Sports Sci
Treadmill Running Test • Maximal, incremental test on a running treadmill v0 = 6 km·h-1 v = 1 km·h-1 / 1 min slope 5% • Expired gas continuously measured BxB CPXII, Medical Graphics, USA • Highest 15 s averaged VO2 = VO2max • Ventilatory thresholds VT1 VT2 = RCP
Statistical Analysis • MANOVA (general linear model, SPSS) • Main effects time: Pre, Post, Post 1 wk, Post 2 wk treatment: HYPO vs NORM • Time x treatment interaction • Post-hoc paired comparisons (Student)
VO2max NORM HYPO NORM HYPO % Change of VO2max % Change of VO2max 18 14 +3.7% 10 p=0.2 6 2 -2 -6 -10 -14 Pre Post 1 Pre Post 1
VT1 NORM HYPO NORM HYPO 12 % Change in VT1 (% VO2max) Group (NORM, HYPO) x Period Change in VT1 (% VO2max) % (pre, post1) = 0.017 8 4 0 -4 +3.5% -8 p<0,05 -12 Pre Post 1 Pre Post 1 Group (NORM, HYPO) x Period (pre, post1) = 0.017
VT2 NORM NORM HYPO HYPO 12 Group % Change in VT2 (% VO2max) (NORM, HYPO) x Time (pre, post1) = 0.00032 2max) % Change in VT2 (% VO * 8 4 +3.8% p<0,001 0 -4 -8 ** -12 Pre Post 1 Pre Post 1
Running Performance NORM HYPO NS main effects (MANOVA) 7 5 3 1 -1 -3 -5 -7 Pre Post Post 2 Pre Post Post 2
Field Running Performance • No changes in MAS in contrast with increased performance +2.9% in 4-min trial in world-class track cyclists (IHE 15)1 +0.9% in 200-m time-trial in swimmers (IHE 10 d)2 consistent with no improvement in 100-400 m and 3 km time-trials in swimmers and runners3 1 Gore et al. (1998) J Sci Med Sport 2 Rodríguez et al. (2002) IX WSBMS 3 Rodríguez et al. 2007 J Appl Physiol
Discussion: VO2max • NS change in VO2max (+3.7%, p=0.2) lower than in Runners (+5%) Hi-Lo at 2,500 m for 4 wk1 Trained climbers (+6.2%), IHE for 17 days2 Swimmers (+5.4%), IHE for 10 days3 similar to Swimmers (+3.3%), IHE for 4 wks4 • Limited scope for increase in highly endurance-trained athletes or reduced sample effect? 1 Levine & Stray-Gundersen (1997) J Appl Physiol 4 Rodríguez et al. (2004) Med Sci Sports Exerc 2 Casas et al. (2000) Aviat Space Environ Med 5 Gore et al. (1998) J Sci Med Sport 3 Rodríguez et al. (2002) IX WSBMS
VT and VCO2max • Significant increase AT1 +3.5% VT2 +3.8% consistent with LT improvement in climbers1,2 and swimmers3 • Significant decrease VCO2max -8.7% • Changes suggesting improvement of aerobic endurance and lower reliance on glycolitic metabolism: mechanism? 1 Rodríguez et al. 1999 Med Sci Sports Exerc 2 Casas et al. 2000 Aviat Space Environ Med 3 Rodríguez et al. 2007 J Appl Physiol
Intermittent Hypoxia Study 2003 HYPO Swimmers NORM Swimmers 30 HYPO NORM +12.1% [7.0 to 17.2] +8.9% [5.4 to 12.5] p < 0.001 20 p = 0.007 % Change in VO2 at VT +0.4% [-2.1 to 2.9] 10 p = 0.98 0 -10 -3.5% [-0.7 to -6.2] p = 0.56 PRE-MEAN POST1 POST2 PRE-MEAN POST1 POST2 Rodríguez et al. 2007 J Appl Physiol Group x Test F(1,10) = 6.80, p = 0.006
Erythropoietic Response • EPO secretion stimulated (mean=100-440%) • No subsequent erythropoietic response1 • Changes not attributable to an increase in total Hbmas as in a double-blind study with runners and swimmers2 1 Abellán et al. 2004 Haematologica 2 Gore et al. 2007 J Appl Physiol
Conclusions • IHE combined with SL training to moderate-severe hypoxia did not improve track running performance (MAS) in triathletes • Unlike in swimmers1, change in VO2max were NS, • This may be explained by limited scope for further increase in ET triathletes limited sample effect 1 Rodríguez et al. 1999 Med Sci Sports Exerc
Conclusions • IHE significantly increased VT and decreased VCO2max suggesting improved aerobic endurance capacity not due to increased erythropoiesis or efficiency other adaptations (ventilatory, mitochondrial)? • Although benefits can be expected, more research is needed to clarify the effect of IHE in endurance athletes
IMAS Institut Municipal d’Investigació Mèdica. IMIM Pharmacology Research Unit