Effect of Low-Load Blood-Flow Restricted Training Versus Heavy Slow Resistance Training in Unilateral Patellar Tendinopathy: A Randomized Clinical Trial

Patellar tendinopathy (PT) is a debilitating overuse injury, and one of the current recommended treatments is heavy slow resistance training (HSRT); Recently, low-load resistance training combined with blood flow restriction (LL-BFRT) has been advocated as a clinically relevant rehabilitation tool for PT since it does not involve large joint and tissue stresses and may accelerate recovery. This study aimed to investigate the effect of LL-BFRT compared with HSRT at 3, 6, 12 (primary endpoint), and 52 weeks. Participants with chronic unilateral PT were randomized to a 12-week rehabilitation program based on either LL-BFRT (n = 16) or HSRT (n = 20). The primary outcome was pain (numerical rating scale (NRS) 0–10) during a single-leg decline squat (SLDS). Secondary outcome variables included the Victorian Institute of Sports Assessment-Patella questionnaire (VISA-P), maximal isometric knee extensor strength, patellar tendon morphology assessed by ultrasonography (swelling, vascularization), and magnetic resonance imaging (MRI). Comparable clinically relevant improvements in pain (NRS during SLDS, least squares mean ± SEM) were observed in LL-BFRT (LL-BFRT: 0 weeks 3.9 ± 0.5, 12 weeks 2.2 ± 0.5, 52 weeks 1.8 ± 0.5) and HSRT (0 weeks 4.2 ± 0.4, 12 weeks 2.2 ± 0.4, 52 weeks 1.1 ± 0.5) (p < 0.0001). Likewise, clinically relevant improvements were reported on the VISA-P score. LL-BFRT and HSRT resulted in comparable short-term and long-term clinical improvements in males with chronic PT. These data advocate that LL-BFRT represents an effective rehabilitation tool in the treatment of chronic PT, while preventing high joint and tendon loads. Trial Registration: Clinicaltrials.org (NCT04550013).