Tendon neuroplastic training reduces tendon pain and muscle inhibition in-season: Changing the way we think about exercise

Introduction: Patellar tendon pain is at its highest in-season but there are no published data of successful management when athletes are playing and training. Furthermore, there are changes to the cortical control of the quadriceps in patellar tendinopathy (including excess quadriceps inhibition) that may not be ameliorated with current loading protocols. Strength training that is externally paced with either visual or auditory cues may not only have positive effects on tendon matrix and muscle properties but may exploit the processes leading to neuroplasticity and improve control of the muscle. The aim of this study was to compare two forms of strength training designed to affect cortical control, during a competitive season, for the effects on tendon pain and cortical inhibition. Methods: This was a randomised clinical trial with two intervention arms. Sub-elite and elite basketball and volleyball athletes aged over 16 years, playing and training three times per week, were recruited and randomised to either isometric or isotonic exercise. Protocols were completed four times per week for four weeks on a leg extension machine. Protocols were matched for time under load and rest between sets, isometric consisted of; 5×45s at 60 degrees and isotonic consisted of; 4×8 (three second concentric and four second eccentric phase). Strength training was externally paced using an audio recording specifically designed for the study. A subgroup of athletes completed testing of cortical control of the quadriceps. Results: Twenty-nine athletes were recruited. Median pain scores improved significantly over the 4-week intervention period in both the isometric group (pre 5.5/10, post 2/10, p = 0.012) and isotonic group (pre 5/10, post 2.5/10, p = 0.003). However, the isometric group reported significantly greater immediate pain relief following each intervention session (p < 0.002). Cortical testing, (n = 9) showed that isometric and isotonic training reduced quadriceps inhibition by 41.3%. Discussion: This study provides clinicians with successful two in-season interventions for patellar tendinopathy. For immediate pain relief, it appears that isometric exercise is superior but both programs were efficacious over the four week block. Isometric and isotonic exercise programs are easy-to-use exercises that can reduce pain from patellar tendinopathy for athletes in-season. Both protocols used externally paced strength training, termed tendon neuroplastic training, which incorporates parameters important for tendon loading but importantly, may contribute to modifying the cortical control of the quadriceps muscle.