ROS Scavenging Activity and Muscle Damage Prevention in Eccentric Exercise in Rats

Abstract

Depending on intensity, eccentric exercise is experimentally and clinically documented to have opposing dual effects on skeletal muscle; intense eccentric exercise damages muscle, but daily low-load eccentric exercise prevents damage. To clarify the mechanisms of this dual effect, microscopic damage and oxidative stress were studied in rat quadriceps muscle. Oxidative stress was estimated from an immunostaining of advanced glycation end-products (AGE) and a measurement of muscle tissue preparations, the ability to scavenge reactive oxygen species (ROS). Intense eccentric downhill running (IEE) induced muscle damage that was, microscopically apparent 3 days later. Since AGE-positive cells and decreased ROS scavenging activity were observed earlier (on the day after IEE), cellular damage may be related to ROS production. Intense concentric uphill running (ICE) induced an immediate but transient decrease in ROS scavenging activity, which recovered within a day. Neither AGE-positive cells nor microscopic damage was observed after ICE. Since each contracting muscle fiber develops greater tension during eccentric rather than concentric exercise, the initial trigger of IEE-induced muscle damage may be damage to muscle fibers and connective tissues at the subcellular level. Daily low-load training of eccentric downhill running (LET), but not concentric uphill running, efficiently prevented muscle damage after subsequent IEE. No evident elevation of ROS scavenging activity was evident after LET. We concluded that LET prevents IEE-induced muscle damage not through elevated ROS scavenging activity, but through a suppression of initial subcellular damage that triggers subsequent ROS-producing processes, resulting in cellular delayed damage.

Establishment of an animal model for delayed-onset muscle soreness after high-intensity eccentric exercise and its application for investigating the efficacy of low-load eccentric training

“…In experiments that we have conducted on rats, we have studied muscle damage and its prevention by making rats perform the eccentric exercise of running downhill. Maruhashi [16] showed that 1 day after a high-intensity eccentric exercise, reactive oxygen species (ROS) were found in the muscles, and that 2-3 days later, evidence of muscle damage was found. These results suggested that ROS is associated with microscopic muscle damage resulting from high-intensity eccentric exercise and that ROS can cause muscle damage.…”

“…Several mechanisms seem to be involved in the process of producing the repeated bout effect, but it remains unclear how the mechanism of low-load eccentric training is involved. Maruhashi [16] reported that when low-load eccentric training is conducted beforehand, the initial subcellular damage that triggers subsequent ROS production 1 day after high-intensity eccentric exercise is inhibited; as a result, secondary muscle damage is prevented. In the current study, we used the same exercise protocols to burden rats with low-load eccentric training and highintensity eccentric exercise.…”

“…Low-load eccentric training involved treadmill running at 10 m/min on a 15°incline for 30 min a day for a week (30 min 9 1 set per day). These exercise protocols were used based on the findings of Maruhashi et al [16]: high-intensity eccentric exercise was demonstrated to induce muscle injury, and a week of low-load eccentric training was demonstrated to prevent this muscle injury. At each rest interval, food and water were provided ad libitum.…”

Effect of Heat Shock Preconditioning on ROS Scavenging Activity in Rat Skeletal Muscle after Downhill Running

“…The contradictory results of these previous studies might be due to differences in the timing and methods used to measure SOD activity, differences in the exercise training protocols, or differences in the fiber composition of the muscles investigated. Maruhashi et al [35] used the same exercise protocol and technique to assay ROS scavenging activity as in the present study; they reported that low-load eccentric training prevented intense eccentric exercise-induced muscle injury not through elevated ROS scavenging activity, but through a suppression of initial subcellular damage that triggered subsequent inflammatory cell infiltration and ROS production. Since the present study showed that HS has the ability to increase ROS scavenging activity, there is a possibility that it also has a distinct mechanism to prevent exercise-induced muscle injury compared to lowload eccentric training.…”

Effect of eccentric training on mitochondrial function and oxidative stress in the skeletal muscle of rats

“…Detailed mechanisms underlying this dual effect have not yet been fully studied experimentally (36,37). Vissing et al (38) showed that this heat shock protein response to eccentric exercise was concurrently attenuated with attenuation of muscle damage when eccentric exercise was repeated 8 weeks later.…”