# Effects of Superimposed Blood Flow Restriction on Isokinetic Knee Extension

## TL;DR

This study found that applying blood flow restriction during knee extension exercises does not significantly improve muscle performance in physically active adults.

## Contribution

The study introduces new empirical evidence on the effects of blood flow restriction during isokinetic exercises on muscle performance.

## Key findings

- No significant differences were found in the isokinetic concentric moment of knee extensors with or without blood flow restriction.
- There were significant differences in interactions by gender, but not by blood flow restriction levels.
- Blood flow restriction at 40% and 80% MPO did not cause acute changes in maximal moment or power production.

## Abstract

Objective: To evaluate changes in the isokinetic concentric moment of the knee extensors and the moment–velocity curve during the application of no BFR compared to superimposed BFR. Methods: A total of 37 physically active adults [33.73 (10.96) years; 11 females] performed three sets of isokinetic concentric knee extensions, each including three angular velocities (300°/s, 210°/s, and 120°/s; BIODEX dynamometer). BFR at 40% (BFR40) and 80% (BFR80) of the maximal pressure occlusion (MPO) were applied randomly after an equal control protocol without BFR (BFR0). Results: No significant differences were found for any interaction between the BFR condition and angular velocity (p > 0.05); 109.78 ± 32.90 vs. 71.24 ± 11.18, 116.68 ± 27.29 vs. 74.40 ± 15.11, and 113.91 ± 28.43 vs. 72.95 ± 13.76 Nm at 300°/s; 137.60 ± 35.27 vs. 88.85 ± 15.23, 135.40 ± 33.04 vs. 86.32 ± 17.38, and 132.68 ± 31.99 vs. 85.39 ± 16.25 Nm at 210°/s; 177.62 ± 41.40 vs. 114.72 ± 20.10, 166.40 ± 45.39 vs. 198.14 ± 21.80, and 162.60 ± 40.10 vs. 109.09 ± 18.90 Nm at 120°/s, for BFR0, BFR40, and BFR80, respectively. There were significant differences in the interactions by gender. Conclusions: Superimposed application of BFR at 40% MPO and 80% MPO during an isokinetic knee extension did not cause any acute change in the ability to produce maximal moment or power. The use of BFR may not generate an ergogenic effect that is sufficient to cause acute changes in force production.