title: Reactive oxygen/nitrogen species and contractile function in skeletal muscle during fatigue and recovery.
abstract: The production of reactive oxygen/nitrogen species (ROS/RNS) is generally considered to increase during physical exercise. Nevertheless, direct measurements of ROS/RNS often show modest increases in ROS/RNS in muscle fibres even during intensive fatiguing stimulation, and the major source(s) of ROS/RNS during exercise is still being debated. In rested muscle fibres, mild and acute exposure to exogenous ROS/RNS generally increases myofibrillar submaximal force, whereas stronger or prolonged exposure has the opposite effect. Endogenous production of ROS/RNS seems to preferentially decrease submaximal force and positive effects of antioxidants are mainly observed during fatigue induced by submaximal contractions. Fatigued muscle fibres frequently enter a prolonged state of reduced submaximal force, which is caused by a ROS/RNS-dependent decrease in sarcoplasmic reticulum Ca(2+) release and/or myofibrillar Ca(2+) sensitivity. Increased ROS/RNS production during exercise can also be beneficial and recent human and animal studies show that antioxidant supplementation can hamper the beneficial effects of endurance training. In conclusion, increased ROS/RNS production have both beneficial and detrimental effects on skeletal muscle function and the outcome depends on a combination of factors: the type of ROS/RNS; the magnitude, duration and location of ROS/RNS production; and the defence systems, including both endogenous and exogenous antioxidants.
authors: Karolinska Institutet, Stockholm, SE-171 77, Sweden.
authors: Arthur J
authors: AJ
authors: Cheng
authors: Sapporo Medical University, Sapporo, Japan.
authors: Takashi
authors: T
authors: Yamada
authors: McGill University, 475 Pine Avenue West, Montreal, QC, Canada, H2W1S4.
authors: Dilson E
authors: DE
authors: Rassier
authors: Karolinska Institutet, Stockholm, SE-171 77, Sweden.
authors: Daniel C
authors: DC
authors: Andersson
authors: Karolinska Institutet, Stockholm, SE-171 77, Sweden. hakan.westerblad@ki.se.
authors: Håkan
authors: H
authors: Westerblad
authors: Karolinska Institutet, Stockholm, SE-171 77, Sweden.
authors: Johanna T
authors: JT
authors: Lanner
mesh_terms: D000818:Animals; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species