title: Ischemic Preconditioning Enhances Muscle Endurance during Sustained Isometric Exercise.
abstract: Ischemic preconditioning (IPC) enhances whole-body exercise endurance. However, it is poorly understood whether the beneficial effects originate from systemic (e. g., cardiovascular system) or peripheral (e. g., skeletal muscle) adaptations. The present study examined the effects of IPC on local muscle endurance during fatiguing isometric exercise. 12 male subjects performed sustained isometric unilateral knee-extension exercise at 20% of maximal voluntary contraction until failure. Prior to the exercise, subjects completed IPC or control (CON) treatments. During exercise trial, electromyography activity and near-infrared spectroscopy-derived deoxygenation in skeletal muscle were continuously recorded. Endurance time to task failure was significantly longer in IPC than in CON (mean±SE; 233±9 vs. 198±9 s, P<0.001). Quadriceps electromyography activity was not significantly different between IPC and CON. In contrast, deoxygenation dynamics in the quadriceps vastus lateralis muscle was significantly faster in IPC than in CON (27.1±3.4 vs. 35.0±3.6 s, P<0.01). The present study found that IPC can enhance muscular endurance during fatiguing isometric exercise. Moreover, IPC accelerated muscle deoxygenation dynamics during the exercise. Therefore, we suggest that the origin of beneficial effects of IPC on exercise performance may be the enhanced mitochondrial metabolism in skeletal muscle.
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Tanaka
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Suga
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kido
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Honjo
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Fujita
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hamaoka
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Isaka
mesh_terms: D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D006801:Humans; D019194:Ischemic Preconditioning; D007537:Isometric Contraction; D007717:Knee; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D010100:Oxygen / Q000502:physiology; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen