Effect of an inverted seated position with upper arm blood flow restriction on measures of elbow flexors neuromuscular performance.

• Main Authors: Hamid Ahmadi, Nehara Herat, Shahab Alizadeh, Duane C Button, Urs Granacher, David G Behm
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2021-01-01
• Series: PLoS ONE
• Online Access: https://doi.org/10.1371/journal.pone.0245311

<h4>Purpose</h4>The objective of the investigation was to determine the concomitant effects of upper arm blood flow restriction (BFR) and inversion on elbow flexors neuromuscular responses.<h4>Methods</h4>Randomly allocated, 13 volunteers performed four conditions in a within-subject design: rest (control, 1-min upright position without BFR), control (1-min upright with BFR), 1-min inverted (without BFR), and 1-min inverted with BFR. Evoked and voluntary contractile properties, before, during and after a 30-s maximum voluntary contraction (MVC) exercise intervention were examined as well as pain scale.<h4>Results</h4>Inversion induced significant pre-exercise intervention decreases in elbow flexors MVC (21.1%, [Formula: see text] = 0.48, p = 0.02) and resting evoked twitch forces (29.4%, [Formula: see text] = 0.34, p = 0.03). The 30-s MVC induced significantly greater pre- to post-test decreases in potentiated twitch force ([Formula: see text] = 0.61, p = 0.0009) during inversion (↓75%) than upright (↓65.3%) conditions. Overall, BFR decreased MVC force 4.8% ([Formula: see text] = 0.37, p = 0.05). For upright position, BFR induced 21.0% reductions in M-wave amplitude ([Formula: see text] = 0.44, p = 0.04). There were no significant differences for electromyographic activity or voluntary activation as measured with the interpolated twitch technique. For all conditions, there was a significant increase in pain scale between the 40-60 s intervals and post-30-s MVC (upright<inversion, and without BFR<BFR).<h4>Conclusion</h4>The concomitant application of inversion with elbow flexors BFR only amplified neuromuscular performance impairments to a small degree. Individuals who execute forceful contractions when inverted or with BFR should be cognizant that force output may be impaired.