Repeated activation of skeletal muscle causes fatigue, which involves a red
uced ability to produce force and slowed contraction regarding both the spe
ed of shortening and relaxation. One important component in skeletal muscle
fatigue is a reduced sarcoplasmic reticulum (SR) Ca2+ release. In the pres
ent review we will describe different types of fatigue-induced inhibition o
f SR Ca2+ release. We will focus on a type of long-lasting failure of SR Ca
2+ release which is called low-frequency fatigue, because this type of fati
gue may be involved in the muscle dysfunction and chronic pain experienced
by computer workers. Paradoxically it appears that the Ca2+ released from t
he SR, which is required for contraction, may actually be responsible for t
he failure of SR Ca2+ release during low-frequency fatigue. We will also di
scuss the relationship between gross morphological changes in muscle fibres
and long-lasting failure of SR Ca2+ release. Finally, a model linking musc
le cell dysfunction and muscle pain is proposed.