Context:: Blood flow-restricted training (BFRT) has been suggested to treat lower extremity muscle weakness. The efficacy of BFRT for muscle problems related to knee pathology is unclear.
Objective:: To determine whether BFRT (1) improves muscle strength and cross-sectional area (CSA) for chronic knee-related lower extremity atrophy and (2) prevents muscle atrophy after knee surgery.
Data sources:: A systematic review of the literature from 1974 to 2017 was conducted using the PubMed and Cochrane databases.
Study selection:: Controlled trials that used BFRT to treat chronic knee-related lower extremity muscle atrophy or to prevent muscle atrophy after knee surgery that measured the effects on quadriceps or hamstrings muscle strength or CSA were included.
Study design:: Systematic review.
Level of evidence:: Level 2.
Data extraction:: Data were extracted as available from 9 studies (8 level 1, 1 level 2). Assessment of study quality was rated using the Physiotherapy Evidence Database or Methodological Index for Non-Randomized Studies instruments.
Results:: BFRT was used after anterior cruciate ligament reconstruction and routine knee arthroscopy and in patients with knee osteoarthritis or patellofemoral pain. There were a total of 165 patients and 170 controls. Vascular occlusion and exercise protocols varied; all studies except 1 incorporated exercises during occlusion, most of which focused on the quadriceps. Six of 7 studies that measured quadriceps strength reported statistically significant improvements after training. Few benefits in quadriceps CSA were reported. Hamstrings strength was only measured in 2 studies. There were no complications related to training.
Conclusion:: Published limited data show BFRT to be safe and potentially effective in improving quadriceps muscle strength in patients with weakness and atrophy related to knee pathology. The use of short-duration vascular occlusion and light-load resistance exercises appears safe after knee surgery or in arthritic knees. This treatment option requires further investigation to refine protocols related to cuff pressure and exercise dosage and duration.
Keywords: blood flow resistance training; quadriceps strengthening; resistance training.