乳酸 にゅうさん noun lactic acid technical 1. lactic acid An organic acid produced by fermentation and by muscles during intense exercise. Familiar from fermented foods and from the discussion of muscle fatigue. 運動(うんどう)で乳酸(にゅうさん)がたまる。🔊 Lactic acid builds up from exercise. ヨーグルトは乳酸菌(にゅうさんきん)で作(つく)られる。🔊 Yogurt is made with lactic acid bacteria. 激(はげ)しい運動(うんどう)のあと、筋肉(きんにく)に乳酸(にゅうさん)がたまって重(おも)く感(かん)じる。🔊 After hard exercise, lactic acid accumulates in the muscles and they feel heavy. Common collocations乳酸(にゅうさん)がたまる: lactic acid builds up乳酸菌(にゅうさんきん): lactic acid bacteria乳酸(にゅうさん)発酵(はっこう): lactic fermentationNote: 乳酸菌(にゅうさんきん) (lactic acid bacteria) is the everyday term seen on yogurt and other fermented-food labels. general Added 2026.5.22 12:04 · Revised 2026.9.2 13:02 27500/27900_nyuusan