Isometric exercises are a form of resistance training in which muscle contractions occur without commensurate changes in joint position or muscle length. Isometric exercises involve holding a static position for a predetermined period of time, as opposed to the repetitive movements of dynamic exercises.
The term "isometric" is derived from the Greek words "isos" (meaning equal) and "metron" (meaning measure) and refers to a form of exercise in which the muscles contract and relax evenly while maintaining a constant length.
Isometric exercises have the benefit of being essentially portable and requiring minimal setup. Incorporating them into physical therapy, rehabilitation, and athletic training can increase muscular strength, stability, and endurance. Isometrics can be utilized to strengthen both individual muscles and the entire body.
Isometric exercises involve contracting muscle fibers to generate resistance to an external force or your own body weight. During contraction, muscle tension is generated, which stimulates motor units and results in strength gains over time.
The challenge is to maintain the contraction for a predetermined period of time, typically between 10 and 30 seconds, although more experienced practitioners may use lengthier holds.