Pressure point: blood flow restriction exercise and the pain paradox in musculoskeletal injury and persistent pain populations—a narrative review

Musculoskeletal injuries are commonly accompanied by acute and persistent pain; the latter of which can lead to maladaptive neurophysiological changes including central sensitisation and altered pain modulation responses. Blood flow restriction (BFR) exercise uses a pneumatic tourniquet to restrict arterial blood flow into the exercising limbs and has emerged as a promising rehabilitation tool, eliciting exercise-induced hypoalgesia (EIH) and increasing muscular strength and mass, but at lower external loads/intensities. The relationship between BFR tourniquet pressure and pain response is, however, complex. This review explores the mechanisms underpinning BFR-induced hypoalgesia and hyperalgesia across clinical and healthy populations. Findings indicate that while BFR exercise can reduce pain, potentially via metabolic, vascular, neurological, and psychological pathways, higher occlusive pressures or individual susceptibility, particularly in those with persistent pain, may provoke hyperalgesia. Mechanistically, this may involve inflammatory cytokine release, upregulated conditioned pain modulation and altered endorphin or endocannabinoid signalling. Psychological factors such as catastrophising and kinesiophobia may, furthermore, exacerbate nociceptive responses. These findings collectively highlight the pleiotropic and potentially hormetic nature of BFR exercise in pain modulation. Careful prescription, pressure selection, and patient monitoring are vital to maximise analgesic benefits while minimising adverse pain responses.