乳酸(にゅうさん)

にゅうさん
noun
lactic acid
technicalscience
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 fermentation

Note: 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.

Watch out

The everyday idea that 乳酸(にゅうさん) building up in the muscles causes fatigue and stiffness is now considered an oversimplification, though the phrase 乳酸(にゅうさん)がたまる is still widely used.

general
Added 2026.5.22 12:04 · Revised 2026.10.11 4:42
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