Neural modulation of muscle contractile properties during fatigue: afferent feedback dependence

Análise eletromiográfica e força do grupo muscular extensor do punho durante isquemia induzida

“…The results of the present study are in accordance with the findings of Farina, Gazzoni and Camelia 10 , who in a situation of ischemia, did not observe any significant change in the amplitude of the electromyographic Bandeira CCA, Berni KCS, Rodrigues-Bigaton D signal of the abductor pollicis brevis muscle, which was submitted to 16 minutes of blood flow occlusion. However, they disagree with the findings of Leonard et al 25 , who observed a decrease in the RMS values of the soleus muscle after 8 to 12 minutes of ischemia.…”

“…There is a discrepancy in the literature as for the type of muscle fiber affected by ischemia. Studies suggest that the type-I slow fibers are the most susceptible ones as they depend on an adequate blood and oxygen supply to synthesize the ATP 25 . Nonetheless, there are reports attesting that ischemia led to more pronounced changes in the conduction velocity of type-II muscle fibers, given the fact that they are quick contraction fibers and consequently produce more metabolic byproducts during muscle contraction 27 .…”

Increased muscle volume and strength following six days of low-intensity resistance training with restricted muscle blood flow

“…Another possible factor for the training effects observed in the LIT-BFR group may be increased muscle activation and apparent elevation in contraction intensity during training session [Takarada et al, 2000]. With complete blood flow occlusion, muscle activation is progressively increased during repetitive low-intensity muscle contractions [Moritani et al, 1992], and there is a reduction in reflex inhibition of alpha motoneurons and inappropriate increases in motor unit recruitment [Leonard et al, 1994]. Our recent work reveals that moderate blood flow restriction and neural compression with cuff inflation results in similar neural manifestations as exercise with complete blood flow occlusion [Yasuda et al, 2008].…”

Hypoxia and Resistance Exercise: A Comparison of Localized and Systemic Methods

“…The size principle suggests that type I fibres are recruited first, with type II fibres being recruited with increasing exercise intensities [105]. Given that the hypoxic condition and metabolite accumulation which occur during BFR exercise can stimulate group III and IV afferents [106][107][108], mechanistically speaking, a reflexive net inhibitory effect on the α-motor neuron may result [109], facilitating increased fibre recruitment to maintain force and protect against conduction failure [106,107]. Therefore, the potential for hypertrophic and strength gains may be augmented by BFR, even at very low training intensities, due to the increased recruitment of type II motor units.…”