isotonics
Isotonicity is a term used in several fields, notably exercise science and clinical medicine. In exercise science, isotonic exercises describe dynamic contractions in which the resistance remains roughly constant while the muscle changes length. These are distinguished from isometric contractions, where muscle length is static, and from isokinetic contractions, where contraction speed is controlled. In practice, true isotonic contraction is an idealization, since resistance and leverage cause varying tension and joint torque throughout a movement. Isotonic training is commonly used to build muscle strength and endurance and is a staple of rehabilitation and general fitness programs.
In physiology and medicine, isotonic solutions have osmolality similar to body fluids, producing no net movement
Overall, isotonicity describes a condition where osmotic pressure is matched to that of body fluids, minimizing