Blood Flow Restriction Training (BFRT) – True Gains?

PM&R News   •   November 2019

Workout

By now many of you have heard of blood flow restriction training (BFRT).  With this relatively novel treatment, few studies have looked at effects on both proximal and distal segments as well as the contralateral limb. 

So remind me again of what BFR training entails?

“low-load exercise performed while wearing an inflatable tourniquet on the proximal limb, which partially restricts arterial inflow and venous return from the extremity.”

In this 6-week randomized controlled-trial¹ 26 participants were observed for effects of strength, torque, work, power, and limb circumference. 16 participants underwent BFRT  while 10 participants formed the control group.

Exclusion Criteria:  circulatory, pulmonary, and hematologic disorders; those currently pregnant or with a history of prior surgery in the affected limb.

Advantages

  • Decreased tissue strain
  • Decreased joint stress
  • Decreased load requirements
  • Initiation of strength training sooner, post-surgery
  • Utilization in de-conditioned population
  • Increased muscle protein synthesis²
  • Improved gene regulation of muscle satellite cells²
  • Improved Fiber recruitment²
  • Increased Hypertrophy²
  • Increased Endurance”²

Methods

Patients had the BFR cuff applied at the proximal thigh and measured for arterial occlusion (re-calibrated every week).  Exercises were completed bilaterally, and only 1 BFR cuff was placed on the thigh of the experimental group. Exercises were performed at 30% of 1-rep max which was determined 1 week prior to initiation of the study.  Each session participants were to maintain a 7-8/10 perceived exertion.  Participants were not allowed to strength train the experimental regions, but encouraged to maintain their normal aerobic program on different days.

BFR training included the following exercises:

  1. Straight-leg raise hip flexion
  2. Side-lying hip abduction
  3. Long-arc quadriceps extension
  4. Standing hamstring curl

Results

The BFRT group saw an increase in both thigh & leg circumference, strength gains (both proximal and distal of the occluded limb), and an increase in knee extension torque, work and power with isokinetic testing compared to the control group.

BFRT                                                    Control

  • Torque:                                                                      11%                         vs.                          3%

  • Work:                                                                         15%                         vs.                         6%

  • Power:                                                                       12%                         vs.                          4%

  • Girth – Thigh:                                                         3.5%                         vs.                        0.8%

  • Girth – Leg:                                                             2.8%                         vs.                         0.4%

  • Strength – Knee extension:                                    8%                          vs.                           3%

Comparisons were also made in the same experimental individuals between BFR and non-BFR limb resulting in the following improvements: thigh/leg girth, hip strength, plantar flexion strength, endurance; mixed results were noted for isokinetic testing.

Comparisons were likewise made between the non-BFR limb in the experimental group and the control groups and statistics found increased quadriceps peak torque, plantar flexion strength, and thigh girth.

Other than soreness, the groups did not experience any negative effects from the testing and only 1 individual was unable to be tested at follow-up due inability to return within a 1-week timeframe of completing the training regimen. Based on the results of this study and others, BFR training is a great way to initiate early strength gains in individuals who are unable to tolerate higher load strength training regimens.

References

  1. Bowman, Eric & Elshaar, Rami & Milligan, Heather & Jue, Gregory & Mohr, Karen & Brown, Patty & Watanabe, Drew & Limpisvasti, Orr. (2019). Proximal, Distal, and Contralateral Effects of Blood Flow Restriction Training on the Lower Extremities: A Randomized Controlled Trial. Sports Health: A Multidisciplinary Approach. 11. 194173811882192. 10.1177/1941738118821929.
  2. Takarada Y, Takazawa H, Sato Y, Takebayashi S, Tanaka Y, Ishii N. Effects of resistance exercise combined with moderate vascular occlusion on muscular function in humans. J Appl Physiol (1985). 2000;88:2097-2106.

Photo by Clem Onojeghuo on Unsplash

Review Question

What pressure dosage should be prescribed for adequate BFR?

Answer

Pressure for each patient should be individually prescribed at 40-80% of their max (100%) arterial occlusive pressure. The perceived tightness scale was shown to be ineffective in determining arterial occlusion pressure.