Affiliations: [a] Charles Perkins Centre, School of Public Health, the University of Sydney, NSW, Australia | [b] General Education Centre, Tzu Chi University of Science and Technology, Hualien, Taiwan | [c] Sports Science and Research Department, National Sports Training Centre, Kaohsiung, Taiwan | [d] Graduate Institute of Athletics and Coaching Science, National Taiwan Sport University, Taoyuan, Taiwan
Correspondence:
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Corresponding author: Kuei-Hui Chan, Graduate Institute of Athletics and Coaching Science, National Taiwan Sport University, 250 Wen Hua 1st Rd., Guishan Township, Taoyuan 33301, Taiwan. Tel.: +886 3 328 3201 ext. 2423; Fax: +886 3 328 0619; E-mail: [email protected].
Abstract: BACKGROUND: The ergogenic effect of ischemic preconditioning (IPC) has been widely approved, but the mechanisms underlying the beneficial effects are still not fully clarified. OBJECTIVE: The aim of this study was to examine the effects of IPC on human isokinetic muscular function and hemodynamics during exercise. METHODS: In a counterbalanced, crossover study, 14 healthy non-athletic males (26.0 ± 3.5 years) performed isokinetic muscle strength and endurance tests of the dominant leg on an isokinetic dynamometer, preceded by either IPC on bilateral thighs (3 × 5-min compression/5-min reperfusion cycles at 50 mmHg greater than the participant’s systolic blood pressure) or SHAM (10 mmHg) intervention. Participants underwent strength testing by performing three maximum isokinetic knee extensions and flexions at the angular velocities of 30⋅∘s-1, 150⋅∘s-1, and 270⋅∘s-1. An endurance test was also conducted over 30 repetitions at 180∘/s. Hemodynamics of the vastus lateralis muscle were monitored before and after the interventions and during exercise tests by near-infrared spectrometer (NIRS). RESULTS: Resting total hemoglobin significantly increased after IPC (p= 0.048, d= 0.15). During the endurance testing, the oxygen uptake was significantly improved after IPC as shown by the change of oxygenated hemoglobin, deoxygenated hemoglobin, and oxygen saturation, at small to moderate effect size. However, both muscular strength and endurance were found unchanged. CONCLUSION: IPC improves the local oxygenation status without altering maximal muscle strength and endurance in young non-athletic males.
