Seven days of ischemic preconditioning augments hypoxic exercise ventilation and muscle oxygenation in recreationally trained males
- Department of Kinesiology and Sport Sciences, School of Education and Human Development, University of Miami, Coral Gables, Florida; Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts; Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts; Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee
- Department of Physical Therapy, University of Miami Miller School of Medicine, Coral Gables, Florida
- Department of Educational and Psychological Studies, School of Education and Human Development, University of Miami, Coral Gables, Florida
- Department of Kinesiology and Sport Sciences, School of Education and Human Development, University of Miami, Coral Gables, Florida
This investigation sought to assess whether single or repeated bouts of ischemic preconditioning (IPC) could improve oxyhemoglobin saturation ([Formula: see text]) and/or attenuate reductions in muscle tissue saturation index (TSI) during submaximal hypoxic exercise. Fifteen healthy young men completed submaximal graded exercise under four experimental conditions: 1) normoxia (NORM), 2) hypoxia (HYP) [oxygen fraction of inspired air ([Formula: see text]) = 0.14, ∼3,200 m], 3) hypoxia preceded by a single session of IPC (IPC1-HYP), and 4) hypoxia preceded by seven sessions of IPC, one a day for 7 consecutive days (IPC7-HYP). IPC7-HYP heightened minute ventilation (V̇e) at 80% HYP peak cycling power output ( Wpeak) (+10.47 ± 3.35 L·min−1, P = 0.006), compared with HYP, as a function of increased breathing frequency. Both IPC1-HYP (+0.17 ± 0.04 L·min−1, P < 0.001) and IPC7-HYP (+0.16 ± 0.04 L·min−1, P < 0.001) elicited greater oxygen consumption (V̇o2) across exercise intensities compared with NORM, whereas V̇o2was unchanged with HYP alone. [Formula: see text] was unchanged by either IPC condition at any exercise intensity, yet the reduction of muscle TSI during resting hypoxic exposure was attenuated by IPC7-HYP (+9.9 ± 3.6%, P = 0.040) compared with HYP, likely as a function of reduced local oxygen extraction. Considering all exercise intensities, IPC7-HYP attenuated reductions of TSI with HYP (+6.4 ± 1.8%, P = 0.001). Seven days of IPC heightens ventilation, posing a threat to ventilatory efficiency, during high-intensity submaximal hypoxic exercise and attenuates reductions in hypoxic resting and exercise muscle oxygenation in healthy young men. A single session of IPC may be capable of modulating hypoxic ventilation; however, our present population was unable to demonstrate this with certainty.
- Research Organization:
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0014664
- OSTI ID:
- 2425794
- Journal Information:
- American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Journal Name: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Journal Issue: 4 Vol. 323; ISSN 0363-6119
- Publisher:
- American Physiological Society
- Country of Publication:
- United States
- Language:
- English
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