Abstract
Eccentric contractions induce muscle damage, which impairs recovery of glycogen and adenosine tri-phosphate (ATP) content over several days. Leucine-enriched essential amino acids (LEAAs) enhance the recovery in muscles that are damaged after eccentric contractions. However, the role of LEAAs in this process remains unclear. We evaluated the content in glycogen and high energy phosphates molecules (phosphocreatine (PCr), adenosine di-phosphate (ADP) and ATP) in rats that were following electrically stimulated eccentric contractions. Muscle glycogen content decreased immediately after the contraction and remained low for the first three days after the stimulation, but increased seven days after the eccentric contraction. LEAAs administration did not change muscle glycogen content during the first three days after the contraction. Interestingly, however, it induced a further increase in muscle glycogen seven days after the stimulation. Contrarily, ATP content decreased immediately after the eccentric contraction, and remained lower for up to seven days after. Additionally, LEAAs administration did not affect the ATP content over the experimental period. Finally, ADP and PCr levels did not significantly change after the contractions or LEAA administration. LEAAs modulate the recovery of glycogen content in muscle after damage-inducing exercise.
Highlights
Eccentric contractions occur when the muscle lengthens as it contracts and can induce ultrastructural disruption of the skeletal muscle that, in turn, induces several unfavorable symptoms lasting for several days up to several weeks [1]
We found that the administration of a leucine-enriched essential amino acids mixture (LEAAs) enhanced the recovery from muscle damage [15], attenuated muscle soreness, and enhanced muscle protein synthesis [16] after eccentric contractions
The muscle glycogen content, decreased after eccentric contractions, was elevated in the eccentric contractions were the given water (EC-Con) and EC-AminoL40 groups, compared to the sedentary group (Sed) group (p < 0.05 and
Summary
Eccentric contractions occur when the muscle lengthens as it contracts and can induce ultrastructural disruption of the skeletal muscle that, in turn, induces several unfavorable symptoms (such as muscle soreness, edema, and muscle dysfunctions) lasting for several days up to several weeks [1]. Several studies have showed that eccentric contractions impair the muscle ability to replenish its glycogen content in human study [4,8] and adenosine tri-phosphate (ATP) content in rodent study [6,7] after eccentric exercise. Adenosine tri-phosphate (ATP) is the fundamental source of energy in the cells, and it is utilized for multiple functions (including muscle contractions, maintenance of ion balance, action potential, etc.). Muscle glycogen is the main energy source for moderate-to-high intensity exercises during which it is metabolized to produce ATP. Post-exercise muscle glycogen repletion, usually rapid following exercise [12], is delayed after running a marathon [13].
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