The present invention provides a composition for improving muscular endurance, which is composed of nutrients, can be ingested safely and can improve muscular endurance easily within a short time and with high efficiency. The composition for improving muscular endurance according to the present invention contains leucine in an amount of 35 mol% or more relative to the total amount of essential amino acids and at least one essential amino acid other than leucine.本發明係提供一種由營養素構成，可安全攝取的同時，簡便且於短時間內獲得以良好效率使肌肉持久力提升之提升肌肉持久力用組成物。 本發明之提升肌肉持久力用組成物，相對於必須胺基酸的總含有量，含有35莫耳％以上的白胺酸，與白胺酸以外的1種以上之必須胺基酸。
