Recent research in strength training physiology revealed that implementation of occlusion garments around the proximal aspect of the lower limbs in combination with low load strength training causes a reduced blood flow and thus providing a high metabolic stimulus, causing a training effect similar to high load training. This study will investigate the added effect of BFR focussing on functional outcome, pain-management and lower limb strength in patients with knee osteoarthritis. Therefore, 234 patiens will be divided into three equal groups (n=78), (control group, sham group and BFR-group) which will be subjected to a 12-week during standard strength training program, 2 times a week for 60 minutes. The first group, which will be submitted to low load resistance training commonly used in contemporary physiotherapy for OA, will serve as a control group whereas both the BFRT and Sham groups will objectify the additional value of implementing vascular occlusion in respective low load resistance training protocol.

Recent research in strength training physiology, revealed that implementation of occlusion garments around the proximal aspect of the segment submitted to strength training (i.e. the upper thigh, in case of lower limb and knee joint training) results in significant increments in metabolic and mechanical muscle loading, facilitating neuromuscular responses in terms of muscle fiber recruitment and muscle fiber hypertrophy/gains in muscle mass, even at fairly low training dosages (<50% of 1RM). As a consequence, BFR guided resistance training at low training intensities renders a training response similar to what can be expected from high intensity strength training. Occlusion at the proximal site of the segment submitted to strength training, reduces both vascular in- and outflow. This reduced blood flow is thought to induce an ischemic/hypoxic environment that enhances the training effect in the exercising muscle, leading to increased muscle mass and strength. In accordance with this theoretic framework, results of a recent study which compared the training effects between High Intensity Resistance Training (HIRT), Low Intensity Resistance Training (LIRT) and Low Intensity Resistance Training with BFR (BFRT), demonstrated that both the HIRT and the BFRT resulted in similar significant improvements in 1RM knee extension strength, functional performance and Quadriceps Cross Sectional Area (CSA), whereas no differences were found after a 12 week period of LIRT. On the contrary, pain scores objectified by means of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) significantly reduced in the BFRT, whereas this was not the case for the HIRT group in which 4 patients were also excluded due to the onset of exercise-induced knee pain. Although previous scientific research has already provided a quite solid proof of concept by assessing the short term results of BFR training in small sample sizes of patients at risk of or suffering from knee OA, ready-to-use guidelines and specific implementation instructions of BFR-based physical therapy and strength training are non-existent at present. With this TBM project, it is our intention to reinforce the scientific evidence regarding the substantial benefits and significant added value of BFR-guided low intensity resistance training in both the stabilization and rehabilitation of knee osteoarthritis, as well as to provide the clinicians ((para)medics and trainers) in hospital, clinical practice and fitness/training settings with specific guidelines with regard to practical implementation of respective exercise protocols.

This will be done using a large scale Randomized Clinical Trial Design in which a standardized strength training protocol will be implemented for functional rehabilitation purposes in a population of 234 participants diagnosed with knee OA, using three different loading categories:

• (n=78) Low Load Resistance Training (Control)
• (n=78) Blood Flow Restricted Low Load Resistance Training (BFRT)
• (n=78) Low Load Resistance Training with sham BFR component (Sham). The first group, which will be submitted to low load resistance training commonly used in contemporary physiotherapy for OA, will serve as a control group whereas both the BFRT and Sham groups will objectify the additional value of implementing vascular occlusion in respective low load resistance training protocol.

The intervention consists of a 12 week during standardised strength program, 2 times a week for 60 minutes. To evaluate and objectify any training effect, patient overall Quality of Life (QoL) and knee function, 4 screening moments are planned; at baseline (week 0), after 6 weeks, post intervention (13 weeks) and a follow-up screening after 6 months to assess the retention effect and thus, the sustainability of this training modality.

Inclusion Criteria:

• Diagnosed with knee osteoarthritis
• Speak Dutch, French or English
• No other pathology restricting patients to participate safe
• Time and motivation to visit 2x/w for 12 weeks

Exclusion Criteria:

• Neurological disorders
• previous surgery or disorder with blood vessels.
• (Symptomatic) heart or vascular disease
• Increased risk for DVT
• Avoiding physical exercise due to medical conditions.
• Rheumatoid arthritis
• BMI >30
• Recent severe trauma or surgery in the lower extremity

Assignment to the BFR or control group was stratified by sex (male/female/X) and affected leg (right, left, both), and only visible for physiotherapists treating patients. The study was single-blinded, as the outcome assessors were blinded from randomization whereas masking of participants was not possible due to the nature of the intervention.