Abstract

Aim: The purpose of this study was to compare the explosive force and electromyographic (EMG) activity at three different times of the day. Methods: Thirty healthy subjects took part in the study, and carried out two maximum isometric voluntary knee extensions to measure explosive force, through contractile impulse (CI) and rate of force development (RFD), and myoelectric signals from quadriceps muscles in the following periods: 07:30-09:30, 13:30-15:30 and 19:30-21:30 (called morning, afternoon and night respectively), on three non-consecutive days. Results: The body temperature was lower in the morning than in the afternoon and night periods. The explosive force, evaluated through contractile impulse (CI) and rate of force development (RFD), was greater at night than in the morning, without differences in the myoelectric signal. Conclusion: The ability to produce explosive force varies throughout different times of the day without variation in muscular recruitment, indicating that peripheral and not neural mechanisms could be responsible for this variation. Verf.-Referat