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Ischemic Preconditioning, O2 Kinetics, and Performance in Normoxia and Hypoxia
- Source :
- Medicine and science in sports and exercise. 51(5)
- Publication Year :
- 2019
-
Abstract
- INTRODUCTION Ischemic preconditioning (IPC) before exercise has been shown to be a novel approach to improve performance in different exercise modes in normoxia (NORM). Few studies have been conducted examining potential mechanisms behind these improvements, and less has been done examining its influence during exercise in hypoxia (HYP). Oxygen uptake and extraction kinetics are factors that have been implicated as possible determinants of cycling performance. We hypothesized that IPC would lead to improvements in oxygen extraction and peripheral blood flow kinetics, and this would translate to improvements in cycling time trial (TT) performance in both NORM and HYP. METHODS Thirteen men (age, 24 ± 7 yr; V˙O2max, 63.1 ± 5.1 mL·kg·min) participated in the study. Subjects completed trials of each combination of normobaric HYP (FiO2 = 0.16, simulating ~8000 ft/2500 m) or NORM (FiO2 = 0.21) with preexercise IPC protocol (4 × 5 min at 220 mm Hg) or SHAM procedure. Trials included submaximal constant load cycle exercise bouts (power outputs of 15% below gas exchange threshold, and 85% of V˙O2max), and a 5-km cycling performance TT. RESULTS Ischemic preconditioning significantly improved 5-km TT time in NORM by 0.9% ± 1.8% compared with SHAM (IPC, 491.2 ± 35.2 s vs SHAM, 495.9 ± 36.0 s; P < 0.05). Ischemic preconditioning did not alter 5-km TT performance times in HYP (P = 0.231). Ischemic preconditioning did, however, improve tissue oxygen extraction in HYP (deoxygenated hemoglobin/myoglobin: IPC, 21.23 ± 10.95 μM; SHAM, 19.93 ± 9.91 μM; P < 0.05) during moderate-intensity exercise. CONCLUSIONS Our data confirm that IPC is an effective ergogenic aid for athletes performing 5-km cycling TT bouts in NORM. Ischemic preconditioning did mitigate the declines in tissue oxygen during moderate-intensity exercise in HYP, but this did not translate to a significant effect on mean group performance. These data suggest that IPC may be of benefit for athletes training and competing in NORM.
- Subjects :
- Adult
Male
medicine.medical_specialty
Adolescent
Physical Therapy, Sports Therapy and Rehabilitation
Athletic Performance
03 medical and health sciences
Young Adult
0302 clinical medicine
Time trial
Oxygen Consumption
Internal medicine
Tissue oxygen
Medicine
Deoxygenated Hemoglobin
Humans
Orthopedics and Sports Medicine
Hypoxia
Ischemic Preconditioning
business.industry
030229 sport sciences
Hypoxia (medical)
Oxygen uptake
Bicycling
Athletes
Cardiology
Exercise Test
Ischemic preconditioning
Constant load
medicine.symptom
business
Oxygen extraction
Subjects
Details
- ISSN :
- 15300315
- Volume :
- 51
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- Medicine and science in sports and exercise
- Accession number :
- edsair.doi.dedup.....b9cc5464622e9a38e26db162e75e5163