Low frequency fatigue of quadriceps muscle after performing maximal isometric contractions at different muscle length

Immediately after performing isometric exercise (males, age 22.9 ±1.8 years, n=12) with maximal intensity (60 s) a greater muscle fatigue and, espacially, lowfrequency fatigue (LFF) after exercise performed at longer muscle length (knee joint angles of 90 degrees) than after the exercise performed at shorter muscle length (knee joint angles of 135 degrees) is observed and it does not depend on muscle length (shorter or longer) at which the muscle fatigue has been registered. There are two periods in recovery of muscle fatigue: rapidly recover (to 3 min) and slow recover. There is an increase in low frequency muscle fatigue during slow muscle recovery period. It is more pronounced after performing exercise at longer muscle length but when LFF registered at shorter length.