Activation of fast‐twitch fibers assessed with twitch potentiation

Abstract

These results are consistent with the concept of "hierarchical order of fiber activation", suggesting that the magnitude of twitch potentiation reflects the activation of fast-twitch fibers during a brief contraction.

Passive Muscle Length Changes Affect Twitch Potentiation in Power Athletes

“…Our isometric data further showed a significant decrease in rising time 10-90 (j8.8% T 8.1%) and HRT (j13.9% T 146%), which is consistent with the studies of Belanger et al (6), Vandervoort et al (38), and Hamada et al (20) for contraction time and TTP twitch. Although not significant in any of the studies investigating HRT, all of them showed a visible trend toward a shorter HRT after conditioning (20,35,38).…”

Twitch potentiation induced by two different modalities of neuromuscular electrical stimulation: Implications for motor unit recruitment

“…Several studies have suggested that twitch potentiation is due mainly to previous activation of type II muscle fibers, both in animal and human models. As such, twitch potentiation magnitude has recently been proposed to reflect activation of type II motor units in plantar flexors …”

“…As such, twitch potentiation magnitude has recently been proposed to reflect activation of type II motor units in plantar flexors. 25 During CONV NMES, motor units are recruited in a nonselective or random manner, i.e., with no obvious sequencing related to fiber type. 10,26 This suggests that, at low force levels, proportionally more type II fibers are recruited during CONV in comparison to voluntary contractions of the same intensity.…”

Utility of electromyographic fatigue threshold during treadmill running

“…With increasing exercise intensity there is an orderly recruitment pattern of muscle fibers from predominantly slow‐twitch fibers (type I) at low intensity to inclusion of fast‐twitch fibers (type II) at high intensity . This neuromuscular response promotes changes in metabolic and EMG parameters as a result of increased muscular work that can be used to predict the onset of fatigue.…”