title: Efficacy of blood flow-restricted, low-load resistance training in women with risk factors for symptomatic knee osteoarthritis.
abstract: OBJECTIVE
  To assess whether concurrent blood flow restriction (BFR) during low-load resistance training is an efficacious and tolerable means of improving quadriceps strength and volume in women with risk factors for symptomatic knee osteoarthritis (OA).
  
  
  METHODS
  Randomized, double-blinded, controlled trial.
  
  
  METHODS
  Exercise training clinical research laboratory.
  
  
  METHODS
  Women over age 45 years with risk factors for symptomatic knee OA.
  
  
  METHODS
  Participants were randomized to either low-load resistance training (30% 1RM) alone (control) or with concurrent BFR and completed 4 weeks of 3 times per week leg-press resistance training. Those randomized to BFR wore a cuff that progressively restricted femoral blood flow over the weeks of training. Intergroup differences in outcome measures were compared using regression methods, while adjusting for BMI.
  
  
  METHODS
  Isotonic bilateral leg press strength, isokinetic knee extensor strength, and quadriceps volume by magnetic resonance imaging were assessed before and after participation. Secondary measures included lower limb muscle power (leg press and stair climb). Knee pain was assessed to determine tolerance.
  
  
  RESULTS
  Of 45 women who consented to study participation, 40 completed the program. There were no significant intergroup differences in baseline characteristics except that body mass index was lower in the BFR group (P = .0223). Isotonic 1RM improved significantly more in the BFR group (28.3 ± 4.8 kg) than in the control group (15.6 ± 4.5 kg) (P = .0385). Isokinetic knee extensor strength scaled to body mass increased significantly more in the BFR group (0.07 ± 0.03 nm/kg) than in the control group (-0.05 ± 0.03 nm/kg) (P = .0048). Changes in quadriceps volume, leg press power, and knee-related pain did not significantly differ between groups.
  
  
  CONCLUSIONS
  Addition of BFR to a 30% 1RM resistance training program was effective in increasing leg press and knee extensor strength in women at risk for knee OA, in comparison with the same program without BFR.
authors.affiliation: Department of Rehabilitation Medicine, The University of Kansas, Kansas City, KS(∗). Electronic address: segal-research@uiowa.edu.
authors.forename: Neil A
authors.initials: NA
authors.lastname: Segal
authors.affiliation: Department of Physical Therapy & Rehabilitation Science; The University of Iowa, Iowa City, IA(†).
authors.forename: Glenn N
authors.initials: GN
authors.lastname: Williams
authors.affiliation: Department of Orthopaedics & Rehabilitation; The University of Iowa, Iowa City, IA(‡).
authors.forename: Maria C
authors.initials: MC
authors.lastname: Davis
authors.affiliation: Department of Epidemiology; The University of Iowa, Iowa City, IA(§).
authors.forename: Robert B
authors.initials: RB
authors.lastname: Wallace
authors.affiliation: Department of Kinesiology; Indiana University-Purdue University Indianapolis, Indianapolis, IN(‖).
authors.forename: Alan E
authors.initials: AE
authors.lastname: Mikesky
mesh_terms: D004311:Double-Blind Method; D005260:Female; D005269:Femur / Q000098:blood supply; D006801:Humans; D053580:Muscle Strength; D020370:Osteoarthritis, Knee / Q000453:epidemiology / Q000503:physiopathology* / Q000534:rehabilitation*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D055070:Resistance Training; D012307:Risk Factors