Clinical Applications of Blood Flow Restriction and Rehabilitation Outcomes

The study aims to evaluate the effect of low load resistance training combined with blood flow restriction or sham blood flow restriction in patients with anterior knee pain and rotator cuff related shoulder pain in a cross-over two-arm randomized, participant and assessor blinded design. More specifically, we aim to investigate the acute and short-term hypoalgesic response (by evaluating pressure pain detection thresholds) of low load exercise with blood flow restriction or sham blood flow restriction, the effect of these interventions in pain during clinical testing, and the possibility of a placebo effect.

Exercise-induced hypoalgesia describes an acute reduction in pain sensitivity following exercise.The hypoalgesic response following different types of exercise (aerobic, resistance) has been widely investigated. Preliminary evidence suggests that blood flow restriction training may decrease pain in patients with musculoskeletal conditions. This effect may result from exercise alone, or from blood flow restriction and exercise in combination. However, the possibility that the effects seen are the result of the placebo effect cannot be discounted. The evidence for the hypoalgesic response (improvement in pain perception) following training with blood flow restriction in anterior knee pain, shoulder pain, and general musculoskeletal conditions, as well as the mechanism of blood flow restriction training inducing acute pain reduction, is sparse.Hence, this study aims to evaluate the effect of low load resistance training combined with blood flow restriction or sham blood flow restriction in patients with anterior knee pain and rotator cuff related shoulder pain in a cross-over two-arm randomized, participant and assessor blinded design. More specifically, we aim to investigate the acute and short-term hypoalgesic response (by evaluating pressure pain detection thresholds) of low load exercise with blood flow restriction or sham blood flow restriction, the effect of these interventions in pain during clinical testing, and the possibility of a placebo effect.

Eligibility Criteria:
Anterior Knee Pain patients We will recruit 40 male adult participants who had consulted a sports medicine physician in a primary care setting for anterior knee pain complaints. A standardized history and physical examination will be conducted by the physiotherapists of the rehabilitation department for inclusion in the study.

Inclusion criteria:

* age over 18 years,
* diagnosis of AKP confirmed by history and physical examination (with or without imaging) for more than six weeks
* non-traumatic history of pain onset
* pain at least during one of the three functional tests used as outcome measure (single-leg shallow leg squat, single-leg deep knee squat, step down)
* pain equal or greater than 3/10 on a numeric pain rating scale (at least in 2/3 functional tests)
* unobstructed knee range of motion and no pain in passive end-range knee extension

Exclusion criteria:

* BMI greater than 28
* systemic pathology including inflammatory joint disease or neoplastic disorders
* history of deep venous thrombosis
* hypertension (systolic pressure \>140mmHg)
* history of endothelial dysfunction
* peripheral vascular disease
* diabetes
* knee pain referred from the spine
* history of previous neurological conditions
* any previous medical treatment including injections (past 3 months) or drug therapy (i.e., anti-inflammatory drugs the last 2 weeks)
* infection
* previous blood flow restriction training
* inability to understand written and spoken English or Arabic.

Rotator cuff related shoulder pain patients We will recruit 40 male adult participants who had consulted a sports medicine physician in a primary care setting for shoulder complaints. A standardized history and physical examination were conducted by the physiotherapists of the rehabilitation department for inclusion in the study.

Inclusion criteria:

* age over 18 years
* rotator cuff related shoulder pain for more than six weeks
* pain greater than 3/10 on a numeric pain rating scale on active abduction and/or resisted external rotation at zero degrees of shoulder abduction (assessed in standing with the arm in slight abducted position)

Exclusion criteria:

* full-thickness rotator cuff tear (positive drop-arm sign and/or radiographic or ultrasonographic evidence)
* BMI greater than 28
* previous shoulder surgery or shoulder fracture
* imaging evidence of severe shoulder osteoarthritis or tendon calcification,\\
* adhesive capsulitis
* systemic pathology including inflammatory joint disease or neoplastic disorders
* restriction of passive range of motion in more than two planes
* history of deep venous thrombosis
* hypertension (systolic pressure \>140mmHg)
* history of endothelial dysfunction
* peripheral vascular disease
* diabetes
* shoulder pain referred from the spine
* history of previous neurological conditions
* any previous medical treatment including injections (past 3 months) or drug therapy (i.e., anti-inflammatory drugs the last 2 weeks)
* infection
* previous BFR training
* inability to understand written and spoken English or Arabic