TY - JOUR
T1 - Effects of normoxic and hypoxic exercise regimens on cardiac, muscular, and cerebral hemodynamics suppressed by severe hypoxia in humans
AU - Wang, Jong Shyan
AU - Wu, Min Huan
AU - Mao, Tso Yen
AU - Fu, Tieh Cheng
AU - Hsu, Chih Chin
PY - 2010/7
Y1 - 2010/7
N2 - Hypoxic preconditioning prevents cerebrovascular/cardiovascular disorders by increasing resistance to acute ischemic stress, but severe hypoxic exposure disturbs vascular hemodynamics. This study compared how various exercise regimens with/without hypoxia affect hemodynamics and oxygenation in cardiac, muscle, and cerebral tissues during severe hypoxic exposure. Sixty sedentary males were randomly divided into five groups. Each group (n = 12) received one of five interventions: 1) normoxic (21% O2) resting control, 2) hypoxic (15% O2) resting control, 3) normoxic exercise (50% maximum work rate under 21% O2; N-E group), 4) hypoxic-relative exercise (50% maximal heart rate reserve under 15% O2; H-RE group), or 5) hypoxicabsolute exercise (50% maximum work rate under 15% O2; H-AE group) for 30 min/day, 5 days/wk, for 4 wk. A recently developed noninvasive bioreactance device was used to measure cardiac hemodynamics, and near-infrared spectroscopy was used to assess perfusion and oxygenation in the vastus lateralis (VL)/gastrocnemius (GN) muscles and frontal cerebral lobe (FC). Our results demonstrated that the H-AE group had a larger improvement in aerobic capacity compared with the N-E group. Both H-RE and H-AE ameliorated the suppression of cardiac stroke volume and the GN hyperemic response (Atotal Hb/min) and reoxygenation rate by acute 12% O2 exposure. Simultaneously, the two hypoxic interventions enhanced perfusion (Atotal Hb) and O2 extraction [AdeoxyHb] of the VL muscle during the 12% O 2 exercise. Although acute 12% O2 exercise decreased oxygenation (ΔO2Hb) of the FC, none of the 4-wk interventions influenced the cerebral perfusion, and oxygenation during normoxic/ hypoxic exercise tests. Therefore, we conclude that moderate hypoxic exercise training improves cardiopulmonary fitness and increases resistance to disturbance of cardiac hemodynamics by severe hypoxia, concurrence with enhancing O2 delivery/utilization in skeletal muscles but not cerebral tissues.
AB - Hypoxic preconditioning prevents cerebrovascular/cardiovascular disorders by increasing resistance to acute ischemic stress, but severe hypoxic exposure disturbs vascular hemodynamics. This study compared how various exercise regimens with/without hypoxia affect hemodynamics and oxygenation in cardiac, muscle, and cerebral tissues during severe hypoxic exposure. Sixty sedentary males were randomly divided into five groups. Each group (n = 12) received one of five interventions: 1) normoxic (21% O2) resting control, 2) hypoxic (15% O2) resting control, 3) normoxic exercise (50% maximum work rate under 21% O2; N-E group), 4) hypoxic-relative exercise (50% maximal heart rate reserve under 15% O2; H-RE group), or 5) hypoxicabsolute exercise (50% maximum work rate under 15% O2; H-AE group) for 30 min/day, 5 days/wk, for 4 wk. A recently developed noninvasive bioreactance device was used to measure cardiac hemodynamics, and near-infrared spectroscopy was used to assess perfusion and oxygenation in the vastus lateralis (VL)/gastrocnemius (GN) muscles and frontal cerebral lobe (FC). Our results demonstrated that the H-AE group had a larger improvement in aerobic capacity compared with the N-E group. Both H-RE and H-AE ameliorated the suppression of cardiac stroke volume and the GN hyperemic response (Atotal Hb/min) and reoxygenation rate by acute 12% O2 exposure. Simultaneously, the two hypoxic interventions enhanced perfusion (Atotal Hb) and O2 extraction [AdeoxyHb] of the VL muscle during the 12% O 2 exercise. Although acute 12% O2 exercise decreased oxygenation (ΔO2Hb) of the FC, none of the 4-wk interventions influenced the cerebral perfusion, and oxygenation during normoxic/ hypoxic exercise tests. Therefore, we conclude that moderate hypoxic exercise training improves cardiopulmonary fitness and increases resistance to disturbance of cardiac hemodynamics by severe hypoxia, concurrence with enhancing O2 delivery/utilization in skeletal muscles but not cerebral tissues.
KW - Circulation
KW - Oxygen
KW - Physical activity
UR - http://www.scopus.com/inward/record.url?scp=77954316843&partnerID=8YFLogxK
U2 - 10.1152/japplphysiol.00138.2010
DO - 10.1152/japplphysiol.00138.2010
M3 - 文章
C2 - 20431021
AN - SCOPUS:77954316843
SN - 8750-7587
VL - 109
SP - 219
EP - 229
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 1
ER -