Effects of interval hypoxia on exercise tolerance: special focus on patients with CAD or COPD.
BACKGROUND
Repeated short-term hypoxia (interval hypoxia) has been suggested to increase exercise tolerance by enhancing stress resistance and/or improving oxygen delivery. As low exercise tolerance contributes to mortality in patients with coronary artery disease (CAD) and chronic obstructive pulmonary disease (COPD), interval hypoxia might be a valuable preventive and therapeutic tool for these patients. Yet, mechanisms responsible for the improvement of exercise tolerance are still largely unknown. Therefore, this review intends to present an overview for better understanding of such mechanisms and to stimulate further research work on this important topic.


METHODS
Articles were selected from a search of the PubMed database up to 2009 using the search terms hypoxia, intermittent, interval in various combinations with exercise, capacity, tolerance, CAD, COPD, and various haematological and cardio-respiratory parameters.


RESULTS
Generally, the effects of 2-4 weeks of interval hypoxia on exercise tolerance are contrasting. Whereas aerobic exercise performance improved or remained unchanged, anaerobic performance tended even to worsen. Benefits on exercise tolerance seem to be greater in patients with CAD or COPD when compared to healthy subjects.


CONCLUSIONS
The mechanisms responsible for these benefits are the increases in total haemoglobin mass, lung diffusion capacity, more efficient ventilation, and a decrease in the responsiveness of the adrenergic system to stimulation and/or an increase in parasympathetic activity. If confirmed in further studies, interval hypoxia might become an attractive strategy to complement the known beneficial effects of exercise training, especially in patients with CAD or COPD.
Burtscher
Martin
M
Department of Sport Science, University of Innsbruck, Innsbruck, Austria. martin.burtscher@uibk.ac.at
Gatterer
Hannes
H
Szubski
Christoph
C
Pierantozzi
Emanuela
E
Faulhaber
Martin
M
D000222:Adaptation, Physiological / Q000502:physiology; D003324:Coronary Artery Disease / Q000503:physiopathology* / Q000534:rehabilitation; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D019194:Ischemic Preconditioning; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000534:rehabilitation
Eur J Appl Physiol. 2007 May;100(2):127-35
17297625
Int J Cardiol. 2004 Aug;96(2):247-54
15262041
J Appl Physiol (1985). 1992 Dec;73(6):2701-8
1490988
Eur J Appl Physiol. 2008 May;103(2):203-13
18270729
Adv Exp Med Biol. 2007;618:41-9
18269187
Mol Cell Biochem. 1992 Apr;111(1-2):87-95
1588947
Circulation. 2001 Aug 21;104(8):963-9
11514387
J Appl Physiol (1985). 2005 Jan;98(1):343-9
15448121
High Alt Med Biol. 2008 Spring;9(1):43-52
18331220
Biol Signals Recept. 1999 Jul-Oct;8(4-5):316-22
10494017
J Nucl Cardiol. 2006 Jan-Feb;13(1):69-74
16464719
J Appl Physiol (1985). 2008 Feb;104(2):328-37
18048583
J Appl Physiol (1985). 2003 Nov;95(5):1824-32
12819214
Eur Heart J. 2001 May;22(10):879-86
11350098
J Biomed Sci. 2004 Nov-Dec;11(6):838-46
15591781
J Appl Physiol (1985). 1990 Mar;68(3):833-42
2187852
J Appl Physiol (1985). 2004 Feb;96(2):754-61
14555683
Prog Cardiovasc Dis. 2009 Jan-Feb;51(4):303-12
19110132
J Sports Sci. 2009 Apr;27(6):633-40
19308875
Scand J Med Sci Sports. 2005 Jun;15(3):182-7
15885040
High Alt Med Biol. 2002 Fall;3(3):277-82
12396881
J Hypertens. 2009 Aug;27(8):1648-54
19387363
Wilderness Environ Med. 2000 Summer;11(2):84-8
10921357
Am J Respir Crit Care Med. 2003 Feb 15;167(4):544-9
12446268
Acta Physiol Scand. 2001 Nov;173(3):275-86
11736690
Eur J Appl Physiol. 2007 Jul;100(4):457-67
17450372
Circulation. 2001 Oct 9;104(15):1785-91
11591615
J Appl Physiol (1985). 2001 Apr;90(4):1431-40
11247944
J Appl Physiol (1985). 1994 Mar;76(3):1055-9
8005844
J Appl Physiol (1985). 2007 Sep;103(3):828-34
17556496
Br J Sports Med. 2007 Aug;41(8):537-9
17311807
J Appl Physiol (1985). 2001 Jun;90(6):2476-87
11356816
Circulation. 1986 Aug;74(2):252-61
3731417
Exp Physiol. 2007 Jan;92(1):51-65
17124276
Eur J Appl Physiol. 2005 May;94(1-2):207-15
15609029
Am J Physiol. 1991 Oct;261(4 Pt 1):E419-24
1928333
J Appl Physiol (1985). 2007 Nov;103(5):1523-35
17690191
Respir Physiol Neurobiol. 2003 Nov 14;138(2-3):193-204
14609510
Exp Physiol. 2006 Jan;91(1):221-8
16263798
High Alt Med Biol. 2001 Winter;2(4):501-8
11809090
J Appl Physiol (1985). 2007 Dec;103(6):1973-8
17947502
Med Sci Sports Exerc. 2000 Jun;32(6):1058-66
10862530
J Appl Physiol (1985). 2004 May;96(5):1800-7
14672967
J Physiol. 2006 Sep 15;575(Pt 3):961-70
16809359
J Appl Physiol (1985). 2002 Oct;93(4):1498-505
12235052
Eur J Appl Physiol. 2004 Jun;92(1-2):75-83
14991325
J Appl Physiol (1985). 2007 May;102(5):1953-61
17234798
Respir Physiol Neurobiol. 2006 Apr 28;151(2-3):132-40
16516566
J Appl Physiol (1985). 2001 Apr;90(4):1593-9
11247965
Transl Res. 2007 Feb;149(2):76-84
17240318
Clin Auton Res. 2007 Feb;17(1):13-9
17264976
Am J Physiol Regul Integr Comp Physiol. 2007 May;292(5):R1977-84
17204591
Eur J Appl Physiol Occup Physiol. 1998 Aug;78(3):189-94
9720995
Methods Enzymol. 2007;435:405-19
17998066
J Physiol. 2003 Jul 15;550(Pt 2):605-16
12766243
Chest. 2000 May;117(5 Suppl 1):219S-23S
10843918
J Physiol. 2005 Sep 1;567(Pt 2):689-99
15975977
Int J Sports Physiol Perform. 2009 Mar;4(1):68-83
19417229
Respir Physiol Neurobiol. 2005 Mar;146(1):55-65
15733779
Respir Physiol Neurobiol. 2009 Jan 1;165(1):97-103
19013544
J Sci Med Sport. 2008 Nov;11(6):593-9
17719848
Scand J Med Sci Sports. 2008 Aug;18 Suppl 1:57-69
18665953
Clin Cardiol. 1987 Dec;10(12):783-9
2961494
Am J Epidemiol. 1999 Dec 15;150(12):1289-96
10604771
Med Sci Sports Exerc. 2004 Jul;36(7):1212-7
15235328
J Appl Physiol (1985). 2005 Mar;98(3):889-94
15557011
Chest. 2001 Jul;120(1):88-92
11451821
J Appl Physiol (1985). 2008 Jun;104(6):1625-33
18403450
Respir Physiol. 2000 Oct;123(1-2):39-49
10996186
Chest. 2000 Sep;118(3):697-703
10988191
J Sports Sci. 2007 Feb 15;25(4):431-41
17365530
J Appl Physiol (1985). 2006 Nov;101(5):1386-93
16794028
Exerc Sport Sci Rev. 1992;20:275-96
1623889
Eur J Appl Physiol. 2009 Mar;105(5):815-21
19125287
Eur J Appl Physiol. 2009 Feb;105(3):403-9
18998153