Elevated muscle vitamin E does not attenuate eccentric exercise-induced muscle injury.

Area of Science:

• Exercise Physiology
• Muscle Biology
• Nutritional Biochemistry

Background:

• Eccentric exercise can cause skeletal muscle damage.
• Oxidative stress is implicated in exercise-induced muscle injury.
• Vitamin E is an antioxidant that may protect against muscle damage.

Purpose of the Study:

• To investigate the effect of elevated muscle vitamin E on skeletal muscle damage after eccentric exercise.
• To determine if increased vitamin E content in muscle attenuates exercise-induced injury.

Main Methods:

• Sixty Sprague-Dawley rats were fed either a normal or vitamin E-supplemented diet for 5 weeks.
• Eccentric exercise was induced via a downhill walking protocol.
• Muscle damage was assessed by measuring maximal tetanic force, intact fiber count, glucose 6-phosphate dehydrogenase activity, and plasma creatine kinase activity.

Main Results:

• Muscle vitamin E levels were 3- to 4-fold higher in supplemented rats.
• Vitamin E supplementation did not reduce skeletal muscle damage markers.
• Maximal tetanic force, intact fiber count, glucose 6-phosphate dehydrogenase activity, and plasma creatine kinase activity showed similar changes in both groups post-exercise.

Conclusions:

• Elevated muscle vitamin E content does not protect against skeletal muscle damage from eccentric exercise.
• These findings do not support a major role for free radical damage in the initiation of eccentric exercise-induced muscle injury.
• Further research is needed to fully elucidate the role of free radicals in muscle damage etiology.