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

Abstract

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. 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. 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). 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.