slow-twitch fibers

(redirected from Type I fibers)
One of the two main types of skeletal muscle, which contains abundant mitochondria and myoglobin. Red muscle fibres contract and fatigue more slowly than white fibres and generate ATP by aerobic catabolism of glucose and fats, utilizing myoglobin-bound O2

slow-twitch fi·bers

(slō-twich fī'bĕrz)
Histologically distinct skeletal muscle fibers that generate energy predominantly through the aerobic energy transfer system; are selectively recruited in aerobic activities.
Synonym(s): slow-oxidative (SO) fibers, Type I fibers.
References in periodicals archive ?
Type I fibers, so-called slow twitch muscle fibers, are well known to be difficult to fatigue and to have weak occurrence tension.
In VI, the percentage of Type I fibers was significantly higher than that of Type II fibers (P < 0.01).
However, the percentage of Type I fibers is significantly higher than Type II fibers in AG (P < 0.01).
reported that VI has 47[+ or -] % of Type I fibers and 53[+ or -]3 % of Type II fibers.
Type I fibers were not found in the pectoralis major muscle of the RBC and HW quail lines.
Cross-sectional area of type IIB fiber is generally larger, as the growth rate of type IIB fiber after birth is approximately two times greater compared to type I fiber (Oksbjerg et al., 1994).
At a depth of 20mm, type IIA and IIX fibers, showed similar F which were significantly higher than that of type I fibers (Table 1) in the non-exercises horses.
The effect of light physical exercise on the F of different types of muscle fibers at a depth of 20mm, was evaluated and there was a significant decrease in type I fibers (P=0.048), a significant increase in type IIA fibers (P=0.012), and no effect on type IIX fibers.
After training, at a depth of 20mm, showed that the CSA of type IIX fibers was significantly greater than the CSA of type I fibers and similar to the CSA of type IIA fibers.
However, in comparing the CSA of fibers at a depth of 60mm, type IIX fibers showed a significantly greater CSA, followed by type IIA fibers and type I fibers. When the effect of the biopsy depth on CSA for the three types of fibers was examined in non-exercised horses, no difference was observed.
Gotoh (2003) stated that type I fibers had a significant positive correlation, while type IIB fibers had a significant negative correlation with intramuscular fat.
The STN muscle contained predominantly type II fibers while type I fibers were less abundant.