Definition of isotonic in English:



  • 1Physiology
    (of muscle action) taking place with normal contraction.

    • ‘These properties are in agreement with recent experiments on the isotonic response of single muscle fibers carried out by Edman and Curtin.’
    • ‘A good example of isotonic contraction would be free weight training.’
    • ‘This exercise piece is specifically designed for isometric and isotonic neck muscle testing and exercise.’
    • ‘A graduated program of swimming and stationary bicycling, along with isometric, isotonic, and eccentric strengthening in the later stages is prescribed.’
    • ‘The existence of damped oscillations in the isotonic transient response of single muscle fibers therefore argues in favor of the oscillating regime.’
  • 2Physiology
    Denoting or relating to a solution having the same osmotic pressure as some other solution, especially one in a cell or a body fluid.

    • ‘Any solutions, such as antibiotic or isotonic solution, should be included on the label.’
    • ‘Vasopressin continued to act in patients excreting isotonic or hypertonic urine, so hypotonic intake must be avoided in them.’
    • ‘Standard BAL was then performed using three aliquots of 50-ml sterile isotonic saline.’
    • ‘The purpose of this activity is to teach the students about osmosis and the effects of hypotonic, hypertonic, and isotonic solutions on animal cells.’
    • ‘The fluid that surrounds the body cells is isotonic.’
    1. 2.1(of a drink) containing essential salts and minerals in the same concentration as in the body and intended to replace those lost as a result of sweating during vigorous exercise.
      • ‘When you start the London marathon, you've got crowds cheering, you've got pretty girls giving you isotonic drinks.’
      • ‘I will start with nutritional supplements, gels, isotonic drinks, power bars and creatine.’
      • ‘It was a mile and a half up a long hill, before I reached the next isotonic drinks station.’
      • ‘Sometimes it is better to consume isotonic drinks where the carbohydrate source is a concentrated form of glucose.’
      • ‘Constar supplies a range of hot-filled beverage bottle sizes for the full range of juice and isotonic beverage applications.’
      • ‘According to Productscan, PepsiCo launched the most isotonic, energy producing beverages globally in the 12 months to May 2007, followed by The Coca-Cola Company.’


Early 19th century (as a musical term designating a system of tuning, characterized by equal intervals): from Greek isotonos, from isos ‘equal’ + tonos ‘tone’.